极速赛车168 Xuansn, Author at Xuansn Capacitor

极速赛车168 Xuansn Dragon Boat Festival

Xuansn — Wed, 12 Jun 2024 00:46:47 +0000

During the Dragon Boat Festival, Dongguan Xuansn Electronics Co., Ltd. purchases all kinds of fresh ingredients to make Zongzi with the taste of hometown, hoping that every family member can feel the warmth of home during Xuansn Dragon Boat Festival.

Dragon Boat Festival · Customs

The Dragon Boat Festival customs are rich and colorful. These customs revolve around offering sacrifices to dragons, praying for blessings, and warding off disasters, and they embody people’s wishes to welcome good fortune, ward off evil and eliminate disasters.

Eating Zongzi during the Dragon Boat Festival

Aunties use Zongzi leaves, glutinous rice, pork belly, dried shrimps and other ingredients to fold, fill, compact, wrap, and tie them into Zongzi. The glutinous taste seems to wrap up the warmth of my hometown, and every bite is a blend of memories and emotionsThe green willows are heavy with rain, and the five-color new silk is wrapped around the corner Zongzi.
Today, let us say to each other:
Happy Dragon Boat Festival!
All good things will come with “Zongzi”!

Xuansn Electronics Co., Ltd. purchases ingredients and makes Zongzi during the Dragon Boat Festival in Xuansn, hoping that every employee can feel the warmth of their hometown. The customs of the Dragon Boat Festival include offering sacrifices to dragons, praying for blessings, and warding off disasters, which embody people’s auspicious wishes. Zongzi is made of zong leaves, glutinous rice, pork belly, dried shrimp and other ingredients. It has a glutinous taste and makes people recall the warmth of their hometown. I wish Xuansn and his family a healthy Dragon Boat Festival, enjoy the sweetness of time, put aside worries and welcome happiness. ”

For more information about Xuansn Electronics, please click:https://www.xuanxcapacitors.com

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极速赛车168 Lead Pin Electrolytic Capacitor —Actual Data Examples

Xuansn — Fri, 08 Mar 2024 07:35:14 +0000

1 Lead-pin electrolytic capacitor-electrolytic capacitor data that keeps pace with the times

Lead pin electrolytic capacitor —To use electrolytic capacitors well, you must understand the data of electrolytic capacitors, and the data of electrolytic capacitors reflects the manufacturer’s understanding of electrolytic capacitors and the user’s application scenarios.

The data of lead-pin electrolytic capacitors also keep pace with the times. Initially, the data for electrolytic capacitors in vacuum tube circuits only included rated voltage, capacitance, capacitance tolerance, loss factor, leakage current and dimensions. In those days rectifier diodes were electron tubes with high “on” resistance. Compared with the current application status of integrated circuits, vacuum tube circuits are in a high-voltage and low-current state, and the “ripple current” generated is also very small. At the same time, due to the large size of the vacuum tube circuit, there is no strict limit on the size of the electrolytic capacitor.

Even in the era of transistors, there are no special requirements for electrolytic capacitor data, only the size is reduced. Such electrolytic capacitor data only requires one page of 32 pages to put down.

The first real advancement in electrolytic capacitor data came from the switching of computer power supplies. At this time, electrolytic capacitors are required to have a maximum working environment temperature of 85°C, and there are also life requirements – 1000h becomes the bottom line.

The beginning of the computer age gave electrolytic capacitors a maximum operating temperature and lifespan. Electrolytic capacitors were also required to provide data on ripple current withstand capabilities, and then there were ESR data requirements.

These newly added data are reflected on the first page of the data table.

Due to different storage conditions and usage conditions, some electrolytic capacitor data also include storage life parameters at high temperature without bias voltage.

With the widespread application of switching power supplies and frequency converters, more detailed requirements have been put forward for the life of electrolytic capacitors. So in the data sheet of the electrolytic capacitor, the curves of life, temperature, and ripple current appear.

Electrolytic capacitors are widely used in power electronic circuits, and their working conditions are different, which puts forward requirements for the impedance frequency characteristics and ESR frequency characteristics of electrolytic capacitors, so the impedance frequency characteristics and ESR frequency characteristic curves of electrolytic capacitors appeared.

Based on the above two curve families, the temperature conversion coefficient and frequency conversion coefficient of the electrolytic capacitor ripple current are derived, making the data of electrolytic capacitors more complete.

With the “deep cultivation” of power electronic circuits and the widespread application requirements of high-speed switching power semiconductor devices (such as MOSFETs and IGBTs), electrolytic capacitors as DC bus capacitors should provide equivalent series inductance data.

Since the ripple current flowing through the electrolytic capacitor causes heating of the electrolytic capacitor, especially large currents will cause significant heating, the thermal resistance of electrolytic capacitors with various sizes of shells is also integrated into the electrolytic capacitor data sheet. Different electrolytic capacitor manufacturers will give data or curves that they think are appropriate. The more comprehensive the data or curves are, the smoother the application will be and the better the performance of the electrolytic capacitor will be exerted. For power electronics engineers with rich design experience, the more comprehensive the data provided by component manufacturers, the better.

Guide pin electrolytic capacitor-the above is the data analysis of electrolytic capacitors that keeps pace with the times

2 Lead pin type electrolytic capacitor CD03 series data

The appearance of CD03 series general-purpose aluminum electrolytic capacitors is shown in Figure 1-1.

Figure 1-1 Outline diagram of CD03 series general-purpose aluminum electrolytic capacitors
The technical data of CD03 series aluminum electrolytic capacitors are shown in Table 1-1 and Table 1-2.
Table 1-1 Performance overview of CD03 series aluminum electrolytic capacitors

Table 1-2 Electrical parameters of CD03 (CD11) series aluminum electrolytic capacitors

Continued

The rated ripple current test conditions in Table 1-2 are 85°C, 100Hz. Table 1-1 and Table 1-2 are data given in the late 1990s, so they contain ripple current data. After deducting the ripple current, high-temperature load test and high-temperature storage test data, the data given in Table 1-1 and Table 1-2 are closest to the early electrolytic capacitor data.

The CD03 series is an 85℃/1000h product, which is the lowest grade of ethylene glycol electrolytic capacitors. As the application fields of electronic circuits become more and more extensive, there are new requirements for the size of electrolytic capacitors. National standard CD110 has become a general-purpose electrolytic capacitor replacing CD03. The CD03 series has withdrawn from the Chinese electrolytic capacitor market and become history. The fundamental reason is that its performance is far from suitable for today’s low-end applications.

3 Lead pin electrolytic capacitor CD110 series data

CD110 series electrolytic capacitors are upgraded models of CD03 lead-pin electrolytic capacitors. The improved features include: lifespan increased from 1000h of CD03 to 2000h; volume reduced, and the shell size of each specification reduced by at least one size; ripple current increased . The CD110 data in the 2021 Jianghai capacitor sample also adds the temperature conversion coefficient, frequency conversion coefficient, ESR under 120Hz conditions of ripple current, and the curves of life, temperature, and ripple current. Compared with the data of this series of electrolytic capacitors and the data of new electrolytic capacitors, except for the difference in specific data values, there is basically no difference in the data items.

The data of CD110 series aluminum electrolytic capacitors are shown in Table 1-3 ~ Table 1-8.

Brief description: The maximum operating (ambient) temperature is 85°C, the load life is 2000h under the ambient temperature of 85°C, small size, low cost, suitable for general consumer electronics.

Table 1-3 Performance overview of CD110 series aluminum electrolytic capacitors

Table 1-4 Life span

Note: After completing the high temperature test, apply UR to the capacitor for 30min and test after 24h.

Table 1-5 Appearance and dimensions (unit: mm)

Table 1-6 Frequency conversion coefficient of ripple current

Table 1-7 Temperature conversion coefficient of ripple current

Table 1-8 Gas parameters of CD110 series aluminum-aluminum electrolytic capacitors

ContinuedContinued

Continued

CD110 series aluminum electrolytic capacitors are general-purpose electrolytic capacitors with the lowest performance requirements in China. They are characterized by low price (less than 1/2 the price of high-frequency low-resistance aluminum electrolytic capacitors) and can meet performance requirements in applications with low requirements.

The relationship between CD110 series electrolytic capacitor life, temperature and ripple current is shown in Figure 1-2.

Figure 1-2 Relationship between life, temperature, and ripple current

4 Lead pin electrolytic capacitor CD285 series data

CD285 series electrolytic capacitors are high-frequency low-resistance lead-pin electrolytic capacitors. They are low-voltage electrolytic capacitor products with a service life of 105°C and 6000-10000h. They have the lowest ESR and the highest ripple current among high-frequency low-resistance aluminum electrolytic capacitors. models.

The data of CD285 series aluminum electrolytic capacitors are shown in Table 1-9 ~ Table 1-14.

Table 1-9 Performance overview of CD285 series aluminum electrolytic capacitors

Table 1-10 Lifespan

Note: Lead pin electrolytic capacitor—After completing the high temperature test, apply UR to the capacitor for 30min and test after 24h.

Table 1-11 Appearance and dimensions (unit: mm)Table 1-12 Frequency conversion coefficientTable 1-13 Temperature conversion coefficientTable 1-14 Electrical parameters of CD285 series aluminum electrolytic capacitors

ContinuedContinuedContinuedContinuedContinuedThe relationship between CD285 series aluminum electrolytic capacitor life, temperature and ripple current is shown in Figure 1-3.Figure 1-3 Relationship between life, temperature, and ripple current

5 CD26 HS series slim electrolytic capacitor data

Some electronic circuits, such as LED-backlit flat-panel TVs, require that the height of the circuit board plus components should not be higher than 13.8mm. If the thickness of the circuit board (about 1.5mm) and the height of the soldering pins (about 1.5~2.5mm) are deducted, the safety space is not considered ( About 3mm), the height requirement of components shall not be higher than 10mm. For 100~220μF/450V electrolytic capacitors, it is almost impossible to make them “short and fat” with a height of less than 8mm. Therefore, it is necessary to make slender electrolytic capacitors and place them on the circuit board when using them to minimize the Reduce the overall height of the circuit board, and even use multiple parallel connections to meet capacitance requirements.

The data of CD26 HS series aluminum electrolytic capacitors are shown in Table 1-5 ~ Table 1-20.

Table 1-15 Performance overview of CD26HS series aluminum electrolytic capacitors

Table 1-16 Lifespan

Note: Lead pin electrolytic capacitor—After completing the high temperature test, apply UR to the capacitor for 30min and test after 24h.

Table 1-17 Appearance and dimensions (unit: mm)Table 1-18 Frequency conversion coefficient of ripple waveTable 1-19 Temperature conversion coefficient of ripple current

Table 1-20 Electrical parameters of CD26HS series aluminum electrolytic capacitors

Continued

The relationship between CD26 HS series aluminum electrolytic capacitor life, temperature and ripple current is shown in Figure 1-4.

Figure 1-4 Relationship between life, temperature, and ripple current

6 Domestic small high voltage, high temperature, long life electrolytic capacitor CD11 GA series data

In electronic lighting and power adapter applications, electrolytic capacitors need to have a long enough life, especially high-voltage aluminum electrolytic capacitors. Because it is a closed space, the ambient temperature of electrolytic capacitors is very high, and high-temperature resistant aluminum electrolytic capacitors are required, such as 105℃/10000h or 125~130℃/2000~5000h. This section takes the CD11 GA high-temperature electrolytic capacitor as an example.

The performance summary of CD11 GA high temperature electrolytic capacitor is shown in Table 1-21.

Table 1-21 Performance overview of CD11GA high temperature electrolytic capacitorContinued

The relationship between life and size is shown in Table 1-22
Table 1-22 Relationship between life and size

The ripple current frequency conversion coefficient is shown in Table 1-23.
Table 1-23 Ripple current frequency conversion coefficient

The appearance and dimensions of CD11 GA are shown in Table 1-24.
Table 1-24 CD11GA appearance and dimensions (unit: mm)

Continued

Electrical parameter table 1-25
Table 1-25 Electrical parameters of CD11GA series aluminum electrolytic capacitorsContinuedContinuedContinued

7 Lead pin type electrolytic capacitor bent legs

7.1 Requirements for pin bending of lead-pin electrolytic capacitors

Lead-pin electrolytic capacitors can not only be directly plugged into the circuit board, but can also be installed horizontally on the circuit board. The pin spacing of small-diameter high-voltage electrolytic capacitors is relatively small, and assembly on the circuit board may cause the circuit board pad spacing to be too small. If the insulation requirements cannot be met, the electrolytic capacitor pin spacing can be expanded to adapt to the insulation distance requirements on the circuit board.

When the lead-pin electrolytic capacitor is placed horizontally on the circuit board, the leads of the electrolytic capacitor need to be bent to insert into the corresponding pad. According to the bending direction, they are divided into right bend and left bend. The bent pins are bent according to the correct direction. The negative electrode is divided into long curved leg and short curved leg.

In order to limit the insertion position of the lead-pin electrolytic capacitor, it is necessary to bend the pins into a “K” shape or fix the electrolytic capacitor on the pad so that it will not fall off before soldering.

Surface mount electronic components are increasingly used, and many of the original plug-in electronic components are gradually changed to surface mount. The corresponding electrolytic capacitors have also entered the surface mount era. Surface mount electrolytic capacitors can be simply understood as assembling lead-pin electrolytic capacitors on a special surface mount base.

Surface mount electrolytic capacitors are increasingly in demand in cheap electronics, but electrolytic capacitors with surface mount bases cost nearly 40% more than lead-pin electrolytic capacitors. If electrolytic capacitors without surface mount bases can be realized, the cost of surface mount electrolytic capacitors will undoubtedly be significantly reduced. As a result, the bent-leg surface-mount electrolytic capacitor package form came out and replaced many surface-mount electrolytic capacitors with bases in the field of medium and high-voltage electrolytic capacitors.

From the perspective of reliability, electrolytic capacitors should not be bent directly by hand. Doing so will cause damage to the core due to external forces. If it is a prototype test, you need to use tools to clamp the roots of the electrolytic capacitor pins and then bend them manually; if it is mass production, the best solution is for the electrolytic capacitor manufacturer to directly bend and cut the electrolytic capacitor pins according to customer requirements. foot.

Figure 1-5 L-shaped lead pin bent leg chip electrolytic capacitor

7.2 Surface mount bending form

Surface mount bent leg forms can be L-shaped, T-shaped, M-shaped, or Z-shaped.

The L-shaped lead pin bent leg chip electrolytic capacitor is shown in Figure 1-5, and its appearance is shown in Figure 1-6.

Figure 1-6 Appearance of L-shaped lead pin bent leg chip electrolytic capacitor

The L-shaped lead pin bent leg chip electrolytic capacitor has a diameter of 6.3~10mm and a length of 9~20mm, see Table 1-26. The 20mm length is significantly longer than the chip electrolytic capacitor with a surface mount base (10×10mm).

Table 1-26 Dimensions of L-shaped lead pin bent leg chip electrolytic capacitor (unit: mm)

Continued

The T-shaped lead pin bent leg chip electrolytic capacitor is shown in Figure 1-7, the appearance is shown in Figure 1-8, and the overall dimensions are shown in Table 1-27.

Figure 1-7 T-shaped lead pin bent leg chip electrolytic capacitor

Figure 1-8 Appearance of T-shaped lead pin bent leg chip electrolytic capacitor
Table 1-27 Dimensions of T-shaped lead pin bent leg electrolytic capacitor (unit: mm)

The M-shaped lead-pin bent-leg chip electrolytic capacitor is shown in Figure 1-9, and its appearance is shown in Figure 1-10.

Figure 1-9 M type lead pin bent leg chip electrolytic capacitor

Figure 1-10 Appearance of M-type lead pin bent leg chip electrolytic capacitor
By slightly modifying the shape of the M-shaped lead pin bent leg, you can obtain a C-shaped lead pin bent leg chip electrolytic capacitor. The appearance is shown in Figure 1-11, and the overall dimensions are shown in Table 1-28.

Figure 1-11 Appearance of C-shaped lead pin bent leg chip electrolytic capacitor
Table 1-28 Dimensions of C-type lead pin bent leg chip electrolytic capacitor (unit: mm)

The Z-type lead pin bent leg chip electrolytic capacitor is shown in Figure 1-12, and its appearance is shown in Figure 1-13.

Figure 1-12 Z-shaped lead pin bent leg chip electrolytic capacitor

Figure 1-13 Appearance of Z-shaped lead pin bent leg chip electrolytic capacitor

7.3 Horizontal installation method with bent legs

Guide pin electrolytic capacitors can be installed vertically or horizontally using plug-in methods. Horizontal installation requires bending the pins. The simplest is straight leg bending, and different manufacturers give different markings, as shown in Figure 1-14. In order to suit the different assembly directions of the circuit board, the horizontal bent legs need to be divided into right and left bends.

Figure 1-14 Appearance of plug-in bent leg chip electrolytic capacitor
The bent leg form can also adopt the outer “K” bent leg method, as shown in Figure 1-15.

Figure 1-15 Appearance of plug-in external K-shaped leg chip electrolytic capacitor

Small diameter electrolytic capacitors have smaller pitches, such as 2.5mm or 3.5mm. In order to meet the creepage distance requirements of the circuit board, the foot spacing needs to be enlarged. Figure 1-16 shows the bent foot method of extending the pins outward.Figure 1-16 Appearance of plug-in type externally expanded bent leg chip electrolytic capacitor

In order to facilitate circuit board wiring, electrolytic capacitors with bent legs can also be staggered with positive and negative electrodes, usually with short negative poles and bent legs, as shown in Figure 1-17.

Figure 1-17 Appearance of short negative bent leg chip electrolytic capacitor

7.4 Curved legs for upright installation

There are also various ways of bending the legs for upright assembly.

The pins of small-diameter electrolytic capacitors installed vertically can also use the outward-expanding bent leg method, while some large-diameter electrolytic capacitors use the inward-bending leg method.

Electrolytic capacitors with externally expanded pins or internally contracted pins are shown in Figure 1-18 and Figure 1-19.

Figure 1-18 Expanded cutouts of small-diameter electrolytic capacitors

Figure 1-19 Expanding and retracting legs of lead-pin electrolytic capacitors

Even if there is no need for external expansion and internal contraction, the lead pin electrolytic capacitor can be cut according to user needs, such as internal K cutting and external K cutting, straight cutting, and double K cutting.

Figure 1-20 and Figure 1-21 respectively show the plug-in type inner K-cut pins, outer K-cut pins and straight pin cut method.

Figure 1-20 Inner K-cut pin and outer K-cut pin of plug-in electrolytic capacitor

Figure 1-21 Straight-cut series of plug-in electrolytic capacitors

Summarize:

Lead-pin electrolytic capacitor—Mainly detect the actual data of CD03, CD110, CD285, CD26 series and bent pins of guided-pin electrolytic capacitors..To learn more about lead-pin electrolytic capacitors, please click:https://solidcapacitor.com

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极速赛车168 Fourth Quarter Xuansn Capacitor Commendation Conference

Xuansn — Mon, 29 Jan 2024 07:10:45 +0000

Xuansn Capacitor Commendation Conference—On January 9, 2024, Dongguan Xuansn Electronics Co., Ltd. successfully held the fourth quarter improvement innovation and quality pacesetters commendation conference, aiming to commend employees with outstanding performance in improvement innovation and quality at the conference , spoke highly of the efforts and contributions of outstanding employees, and issued certificates of honor and bonuses in recognition of their outstanding performanceXuansn Capacitor Commendation Conference—Work hard and climb to the top bravely

Xuansn Capacitor Commendation Conference—Chairman’s speech

“The first is to work hard and make a little progress every day; the second is to have an empty cup mentality and humbly accept other people’s opinions. If you can do these two things, I believe everyone present can become a quality model!”Xuansn Capacitor Commendation Conference—progress starXuansn Capacitor Commendation Conference—Quality pacesetterXuansn Capacitor Commendation Conference—Improvement and innovation

The 2023 Commendation Conference was successfully completed! During this year, everyone’s work responsibility, teamwork, and execution capabilities have improved greatly. I hope that everyone will continue to work hard, maintain their love, create an atmosphere of truth-seeking and pragmatism, strengthen management, innovate and create efficiency, strive for excellence, and further clarify the work goals and tasks for 2024. In 2024, starting from the “heart”, let us work together to make new contributions to a better tomorrow for Xuansn!

Summarize：

Xuansn Capacitor Commendation Conference—It is mainly divided into commendation links such as Progress Star, Quality Pacesetter and Improvement and Innovation. This commendation meeting was successfully completed. Let us work together to strive for a better tomorrow for Xuanxuan.To learn more about electrolytic capacitors, please click:https://xuanxcapacitor.com

Company Profile:

Xuansn Electronic is located in Chang’an Town, Dongguan.Our factory currently has an independent production base industrial park with a construction area of 40,000 square meters and complete facilities. Our company currently mainly produces aluminum electrolytic capacitors，is a high-tech enterprise integrating R&D, design, manufacturing, sales and service.

Drawing on advanced international management experience, we have established a research and development system and laboratories, and have passed ISO9001, IS014001, and QC080000 system certifications. At present, all products have passed ROHS, REACH, and TSCA tests and meet international environmental protection requirements.
The company has industry-leading production equipment, more than 250 fully automatic production lines, and a full range of production supporting capabilities. The main products include ultra-small, ordinary, low leakage, high frequency and low resistance, high voltage, conductive foil and other series capacitors.
We have a professional customization team to meet customer needs and can tailor personalized product solutions for customers in various aspects such as hardware and services.
Our production capacity reaches more than 300 million pieces per month, and we are equipped with a 3,000 square meter finished product warehouse to store regular products and create conditions for rapid delivery.
In the future, Dongguan Xuansn Electronics Co., Ltd. will continue to be oriented by customer needs, driven by technological innovation, adhering to a pragmatic, enterprising, rigorous, outstanding and efficient style, actively exploring international and domestic markets, paying close attention to quality as a guarantee, and continuing to provide customers with More competitive products and solutions.

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极速赛车168 Working status of electrolytic capacitors

Xuansn — Tue, 02 Jan 2024 00:57:51 +0000

Working status of electrolytic capacitors – Medium and high-power switching power supplies are composed of rectifiers and inverters, and the two are connected by a DC bus. In the field of high-power power electronic circuits, they are often called DC-Link (DC link). In order for DC-Link to have low impedance over a wide frequency band, a capacitor in parallel with the DC-Link is required, also known as a DC-Link capacitor or a DC bus capacitor.

The current flowing through the DC bus capacitor is divided into two parts. One part is generated by the rectifier. It has a 100Hz component and a switching frequency component of power factor correction (if any). They are specially discussed in Chapter 9 and Chapter 11 respectively. They will not be repeated in this chapter. The other part is the current component of the switching frequency generated by the post-stage inverter circuit part. Different inverter circuit topologies and control modes will produce current components with different switching frequencies. Its circuit topology mainly includes: flyback converter (described in detail in Chapter 9), bridge converter, forward converter, half-bridge converter, asymmetric half-bridge converter, LLC bridge converter device.

1 Working status of electrolytic capacitor – working mode of input capacitor of bridge converter

The bridge converter circuit is shown in Figure 1-1.
In Figure 1-1, C1 is the converter input capacitor, and C2 is the converter output capacitor.
The input current of the bridge converter is shown in Figure 1-2.

Figure 1-1 Bridge converter circuit

Figure 1-2 Input current of bridge converter

For the convenience of analysis, it is assumed that the input current waveform is a rectangular wave.

At this time, the relationship between the input current peak value and the output current is

In the formula, IPM, ISM, and n are the primary side current peak value, secondary side current peak value, and transformer current ratio of the bridge converter, respectively.

The relationship between the input current average value Iav and the peak value is

The relationship between the input current effective value Irms and the peak value is

The effective current value ICrms of the DC-Link capacitor is

For the convenience of analysis, it is assumed that

but

Similarly, the relationship between the effective current value of the DC-Link capacitor (the AC current component of the DC bus current) and the average value of the DC bus current can be obtained as

The relationship between the ratio of the current effective value of the DC-Link capacitor/the average value of the output current and the duty cycle is shown in Table 1-1.

Table 1-1 Relationship between DC-Link capacitor current and duty cycle

Converting the data in Table 1-1 into graphics can describe the relationship between the two more intuitively, as shown in Figure 1-3.

Figure 1-3 The relationship between the ratio of the effective current value of the DC bus capacitor and the average value of the output current and the duty cycle

If the duty cycle is set to 0.9, the effective value of the output current of the DC bus is

n the same way, when the duty cycle is 0.8, IC is 0.5Iav, and when the duty cycle is 0.5, IC is Iav.

It can be seen that in the case of the average DC bus current, as the duty cycle decreases, the current in the DC bus capacitor increases.

As the DC bus voltage increases, the average DC bus current decreases under the same output power, and the duty cycle decreases. The average DC bus current at this time is

When the duty cycle of the switching tube is 0.9, we can get from equation (1-8)

In the same way, the relationship between the duty cycle of different switching tubes and the current coefficient flowing through the DC bus capacitor can be obtained, as shown in Table 1-2.

Table 1-2 The relationship between different switching tube duty cycles and the current coefficient flowing through the DC bus capacitor

To sum up, the following conclusions can be drawn:

1 The working state of the DC bus capacitor of the symmetrical half-bridge converter is the same as that of the full-bridge converter except that the operating voltage is half of the DC bus voltage.

2 The DC bus capacitors of the non-isolated buck converter operate in the same manner as the DC bus capacitors of the full-bridge converter.

Working status of electrolytic capacitor – The above is the analysis of the working mode of the input capacitor of the bridge converter

2 Working status of electrolytic capacitors -Input capacitor operating modes of forward converter and asymmetric half-bridge converter

The forward converter is a type of isolated buck converter. Different from the full-bridge converter, in most cases, the duty cycle of the switching tube of the forward converter must not be greater than 0.5. Generally it is 0.35~0.4. The current waveform obtained by the corresponding forward converter from the DC bus is an approximate rectangular wave current waveform with a duty cycle less than 0.5.

When the duty cycle of the switching tube is 0.4, according to equation (1-8) we can get

According to equation (1-9), the current of the capacitor is

In the same way, the relationship between the duty cycle of different switching tubes and the current coefficient flowing through the DC bus capacitor is shown in Table 1-3.

Table 1-3 The relationship between the duty cycle of different switching tubes and the current coefficient flowing through the DC bus capacitor

The DC link capacitors of the asymmetric half-bridge converter operate in the same manner as the DC link capacitors of the forward converter.

Working status of electrolytic capacitors -The above is an analysis of the input capacitor operating modes of forward converters and asymmetric half-bridge converters.

3 Working status of electrolytic capacitors -Operating modes of output rectifier and output filter capacitor

Bridge converters, forward converters, and asymmetric half-bridge converters all have an inductor in front of the output filter capacitor. Due to the inductor’s ability to suppress changes in current, the output current of the inductor becomes smooth. The main waveforms of the converter output current in the continuous state are shown in Figure 1-4.

In Figure 1-4, the current fluctuation part is the current of the output capacitor, and its DC component is sent to the load.

Therefore, the effective current value of the output filter capacitor is

Figure 1-4 The main waveforms of the converter output current in the continuous state

In the formula, ΔI is the fluctuation peak value of the converter output current in a switching cycle. This value is determined by the switching cycle ton, the inductance of the boost inductor, and the duty cycle. Therefore, ΔI is

Or take 10% to 20% of the average value of the converter output current. The average value of the converter output current is

If ΔI is chosen to be 10% of the average value of the converter output current, then the effective current value of the output filter capacitor is

The effective value of the output current of the converter when the current is continuous is

If ΔI is chosen to be 20% of the average value of the converter output current, then the effective current value of the output filter capacitor is

This current is only equivalent to less than 6% of the average output current of the converter, which is a very low current value for the output filter capacitor.

The effective value of the output current of the converter when the current is continuous is

It can be seen that even if the current fluctuation is selected to be 20% of the converter output current, the effective value of the converter output current is only less than 0.2% higher than the average current value. It can be approximately considered that the average output current of the converter is equal to the output current. Valid values are equal.

Working status of electrolytic capacitors—the above is an analysis of the working modes of the output rectifier and output filter capacitors

Summarize:

Working status of electrolytic capacitors – This article mainly talks about the working modes of bridge converters, forward converters, asymmetric half-bridge converters, output rectifiers and output filter capacitorsIf you want to know more about electrolytic capacitors, please click:https://xuanxcapacitor.com

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极速赛车168 Polymer Electrolytic Capacitor—Performance Analysis

Xuansn — Tue, 12 Dec 2023 03:42:22 +0000

1 Polymer electrolytic capacitor —The proposal of highly conductive polymer electrolytic capacitor

The biggest problem of electrolytic capacitors has always been the large ESR. Although aluminum electrolytic capacitors already have low ESR types, which can significantly reduce the ESR, there is still no qualitative change. ESR is caused by the negative electrode resistance of the electrolytic capacitor. The conductivity of the negative electrode material of conventional (including low ESR) aluminum electrolytic capacitors is relatively low (3ms/cm). The performance of the electrolytic capacitor will not be qualitatively improved without changing the negative electrode material. One of the methods to improve the conductivity of the negative electrode is to use manganese dioxide whose conductivity is close to the negative electrolyte of the aluminum electrolytic capacitor. The conductivity can reach 30mS/cm. At the same time, the anode material should also be changed to metallic tantalum, and the insulating medium should be changed to five. Tantalum oxide, tantalum electrolytic capacitor. The emergence of tantalum electrolytic capacitors has greatly reduced the ESR of electrolytic capacitors, but it is relatively expensive and has limited rated voltage (less than 63V), so film capacitors are often used in many applications (singles can easily reach 40μF/75V and 80μF/ 30V) or ceramic laminated capacitors (single units have reached 200μF/6.3V) instead of electrolytic capacitors to achieve filtering of switching power supplies and power modules. As we all know, the capacitance of film capacitors and ceramic laminated capacitors is far inferior to electrolytic capacitors, and their application is inconvenient. How to further improve the conductivity of the negative electrode material of the electrolytic capacitor is a good way to improve the performance of the electrolytic capacitor and even the performance of the capacitor. In the context of this application demand, the negative electrode of the organic polymer of the solid aluminum electrolytic capacitor can make the conductivity reach 1000mS/ cm is even 10000mS/cm, so the ESR of the electrolytic capacitor made of negative electrode material will be very low! The conductivity of various negative electrode materials of electrolytic capacitors is shown in Figure 1-1.

Figure 1-1 Conductivity of various negative electrode materials of electrolytic capacitors

The structure of the solid aluminum electrolytic capacitor is the same as that of the ordinary aluminum electrolytic capacitor. The difference is that the negative electrode material of the solid aluminum electrolytic capacitor uses a polymer conductive polymer instead of the electrolyte, so that the negative electrode changes from liquid to solid. In addition to leaded solid electrolytic capacitors, laminated solid electrolytic capacitors have also appeared. The structure of the laminated solid aluminum polymer electrolytic capacitor is a unique structure that combines the characteristics of aluminum electrolytic capacitors and tantalum electrolytic capacitors. Like traditional aluminum electrolytic capacitors, the aluminum oxide layer of the positive aluminum foil of the laminated solid aluminum polymer electrolytic capacitor is formed on the positive aluminum foil through a chemical formation process. In the laminated solid aluminum polymer electrolytic capacitor, a highly conductive polymer film is deposited on alumina as the negative electrode, and graphite and silver are used to lead out the solid polymer negative electrode. This is similar to the solid tantalum electrolytic capacitor which uses graphite to combine manganese dioxide. The negative lead is similar.

2 Polymer electrolytic capacitor —a brief description of the manufacturing process of highly conductive polymer solid electrolytic capacitors

The manufacturing process of highly conductive polymer solid electrolytic capacitors mainly includes nailing, carbonization, formation, polymer injection, polymerization, assembly, testing, etc.

The manufacturing process before nailing and coiling is the same as that of liquid electrolytic capacitors. Different from liquid electrolytic capacitors, the rolled capacitor core also requires a “carbonization” process, because in solid electrolytic capacitors, the capacitor paper is useless and is not conducive to the good bonding between the polymer and the positive and negative electrode foils. Electrical contact, so it needs to be ablated or carbonized. This process uses high temperature to carbonize the capacitor paper.

After carbonization, the capacitor core enters the formation process. The formation process is a repair process of damage to the aluminum oxide film of the positive electrode foil caused by all previous manufacturing processes (such as slitting, riveting during the nailing and rolling process of the nailing and rolling machine, etc.), which is similar to the normal temperature aging and high temperature aging processes of liquid electrolytic capacitors. This process needs to be completed before the polymer is injected into the core. Once the polymer is injected into the core, the aluminum oxide film of the positive electrode foil cannot be repaired, eventually causing the solid electrolytic capacitor to be scrapped.

The formation process is to immerse the carbonized core in the formation liquid at a certain temperature of the formation liquid. The formation liquid is the negative electrode, so you only need to apply the positive voltage required for formation to the positive electrode pin of the core until all the damaged parts of the aluminum oxide film of the positive electrode foil are repaired and the formation process is completed.

After formation, the polymer injection process begins. There are two methods of polymer injection: injecting the original material of the polymer into the capacitor core, and completing the polymerization of the polymer in the capacitor core; completing polymerization outside the capacitor core, and then injecting it into the capacitor core. The former is a manufacturing process for low-voltage solid electrolytic capacitors, and the latter is mostly a manufacturing process for high-voltage solid electrolytic capacitors.

Polymers injected into the capacitor core and then polymerized are not suitable for high-voltage solid electrolytic capacitors. The main reason is that the aluminum oxide film of the positive electrode foil of high-voltage solid electrolytic capacitors is relatively thick. The thicker the aluminum oxide film, the more fragile it is and can easily break under the action of external forces, resulting in A short circuit in the solid electrolytic capacitor, or even the stress release process after the solid electrolytic capacitor is subjected to slight vibration or polymerization, can cause the aluminum oxide film of the positive electrode foil to break and short circuit between the positive and negative electrodes.

For low-voltage solid electrolytic capacitors, the aluminum oxide film of the positive electrode foil is very thin and can withstand a certain degree of external force. After the polymer is injected into the core, polymerization can achieve lower ESR, which is important for low-voltage solid electrolytic capacitors.

After the polymer is injected into the core, it enters the polymerization process, which is similar to the curing process of epoxy resin and uses high-temperature polymerization.

The polymer is polymerized outside the capacitor core and then injected into the capacitor core. This process is to polymerize the polymer and break it into a size that can be injected into the capacitor core. Through solvent carrying, the solvent with polymer is impregnated into the capacitor core, and then the solvent is evaporated from the core. Since the amount of polymer that can be loaded into the capacitor core at one time cannot reach the required amount, the capacitance and ESR cannot reach the design values, and it is necessary to repeatedly impregnate the core with the solvent containing the polymer. , then evaporate the solvent and leave the polymer in the capacitor core until the capacitance and ESR reach the design specifications. Relatively speaking, the more times this process is repeated, the better the performance of the capacitor, but the manufacturing cost increases significantly and the manufacturing process takes longer. Comprehensive considerations are needed to adopt the best compromise manufacturing process.

After the solid electrolytic capacitor completes the polymerization process, it actually has all the electrical parameters of the solid electrolytic capacitor. The next step is to install it in the shell, that is, assembly. The assembly process is the same as that of liquid electrolytic capacitors and will not be described again.

After assembly, the solid electrolytic capacitor passes the test and the performance parameters meet the requirements, it is a qualified product and is usually called a good product.

The above is an analysis of the manufacturing process of polymer electrolytic capacitor.

3 Polymer electrolytic capacitor – general electrical parameters of solid electrolytic capacitors

Like other capacitors, the voltage parameter of solid electrolytic capacitors is one of its important parameters. The voltage parameters of solid electrolytic capacitors mainly include formation voltage, rated voltage, etc.

3.1 Polymer electrolytic capacitor –voltage

3.1.1 Formation voltage Formation voltage is divided into positive electrode foil formation voltage and solid electrolytic capacitor core formation voltage.
The positive foil formation voltage is provided by the formation foil manufacturer. This voltage should be higher than the formation voltage of the solid electrolytic capacitor core.

Figure 1-2 shows the relationship between the operating voltage and temperature of a tantalum electrolytic capacitor.

In Figure 1-2, at 85°C, tantalum electrolytic capacitors can operate at rated voltage. As the temperature exceeds 85°C, the actual operating voltage of tantalum electrolytic capacitors decreases at a rate of 8% to 10% per 10°C. 150°C , the actual operating voltage drops to half of the rated voltage.

From the operating voltage and temperature characteristics of tantalum electrolytic capacitors and the temperature characteristics of aluminum electrolytic capacitor foils, it can be inferred that the relationship between the rated voltage of solid aluminum electrolytic capacitors at the highest temperature and the core formation voltage of 70°C is that the formation temperature is 70°C, and the corresponding formation The voltage needs to be about twice the rated voltage corresponding to 125°C!

This conclusion can also be drawn from the solid electrolytic capacitor data. Figure 1-3 shows the relationship between the temperature and the external voltage that can be applied to a solid electrolytic capacitor with a rated voltage of 25V from 1995 to 2000.

Figure 1-2 Relationship curve between operating voltage and temperature

As can be seen from Figure 1-3, when the temperature is higher than 85°C, for every 10°C increase, the applicable voltage is 90% of the voltage at 85°C. When increasing from 85°C to 105°C, the applicable voltage is 85°C. 80% of voltage at temperature.

If the capacitor core is formed at 70°C and the solid electrolytic capacitor works at 125°C, the working voltage drops to about 55% of the 70°C working voltage.

It can be seen that the higher the formation temperature of the capacitor core, the smaller the attenuation of the operating voltage at high temperatures.

Figure 1-3 The relationship between the temperature of a 25V solid electrolytic capacitor and the external voltage that can be applied

3.1.2 Rated voltage The rated voltage UR represents the DC voltage on the capacitor and is determined by the thickness of the dielectric. Rated voltage is the maximum voltage it can withstand at rated temperature.

The rated voltage of solid aluminum electrolytic capacitors can be 2V at low voltage and up to 400V at high voltage. Most of its applications are low-voltage applications, especially mobile phone charger applications.

3.1.3 Reverse voltage Any incorrect polarity voltage caused by DC voltage and AC voltage components must be less than or equal to the allowable polarity reverse voltage.

3.1.4 Polarity mark Solid aluminum electrolytic capacitors are polar electrolytic capacitors. When using lead-pin packages, the long lead pin is the positive pole and the short lead pin is the negative pole. Since the solid aluminum electrolytic capacitor shell does not have a plastic sleeve, the polarity of the capacitor electrode is marked on the aluminum shell, and the marked one is the negative electrode, as shown in Figure 1-4.

3.2 capacitance

Capacitance is the most important parameter of a capacitor.

3.2.1 Capacitance test conditions The capacitance of solid aluminum electrolytic capacitors is the electrostatic capacitance under 120Hz test conditions.

The nominal capacitance value of solid aluminum electrolytic capacitors is the same as that of aluminum electrolytic capacitors and tantalum electrolytic capacitors, using the E12 preferred series.

Figure 1-4 Solid aluminum electrolytic capacitor polarity mark

Solid aluminum electrolytic capacitors can have capacitances from less than one microfarad to thousands of microfarads.

3.2.2 “Temperature Characteristics” of Capacitance The relationship between capacitance and temperature obtained from the capacitor electrode terminal test is the “temperature characteristic” of capacitance, as shown in Figure 1-5.

Figure 1-5 Relationship between capacitance and temperature of solid aluminum electrolytic capacitors

As can be seen from Figure 1-5, the capacitance of solid aluminum electrolytic capacitors changes less with temperature than liquid aluminum electrolytic capacitors, especially in the low temperature range.

3.3.3 Loss factor Although the ESR of solid aluminum electrolytic capacitors is much lower than that of liquid aluminum electrolytic capacitors under high-frequency testing conditions, the loss factor is tested at a frequency of 120Hz. At 120Hz frequency, the ESR of solid electrolytic capacitors mainly depends on If the aluminum oxide film of the positive electrode foil is removed, the loss factor of the solid aluminum electrolytic capacitor is close to or basically the same as that of the liquid aluminum electrolytic capacitor. The relationship between the loss factor and temperature is shown in Figure 1-6.

3.3.4 Leakage current The leakage current of solid aluminum electrolytic capacitors is caused by defects in the aluminum oxide film of the positive electrode foil, which is the same as the leakage current of liquid aluminum electrolytic capacitors. However, it should be noted that liquid aluminum electrolytic capacitors can continuously repair defects in the aluminum oxide film by continuously applying voltage to the electrolytic capacitor, but solid aluminum electrolytic capacitors do not have the ability to repair the aluminum oxide film and need to have smaller leakage current. The relationship between solid aluminum electrolytic capacitor leakage current and applied voltage is shown in Figure 1-7.

Figure 1-6 Relationship between dissipation factor and temperature of solid aluminum electrolytic capacitors

Figure 1-7 Relationship between solid aluminum electrolytic capacitor leakage current and applied voltage
The relationship between leakage current and temperature at the rated voltage of solid aluminum electrolytic capacitors is shown in Figure 1-8.

Figure 1-8 Relationship between leakage current and temperature at rated voltage of solid aluminum electrolytic capacitors

Like liquid electrolytic capacitors, the leakage current of solid aluminum electrolytic capacitors increases with temperature.

The above is an analysis of the general electrical parameters of polymer electrolytic capacitor.

4 Polymer electrolytic capacitor – impedance characteristics

4.1 Polymer electrolytic capacitor –equivalent series resistance

Similar to liquid aluminum electrolytic capacitors, the ESR of solid aluminum electrolytic capacitors is also composed of the ESR generated by the aluminum oxide film and the ESR generated by the electrolyte (or highly conductive polymer), thus producing the frequency characteristics of the ESR. The frequency characteristic curve of ESR is shown in Figure 1-9.

Figure 1-9 Frequency characteristic curve of ESR

As can be seen from Figure 1-9, as the frequency increases, the ESR of the solid aluminum electrolytic capacitor decreases. This characteristic is similar to the frequency characteristic of the ESR of the liquid aluminum electrolytic capacitor. Taking a 4.7μF/25V solid aluminum electrolytic capacitor as an example, the ESR at a frequency of 100Hz is about 3Ω, while the ESR in the 1 to 10MHz frequency band is about 0.05Ω. The difference between the two is about 60 times. If only considered from the same perspective as heating due to current flowing through ESR, the 100Hz ripple current of this solid aluminum electrolytic capacitor is only 13% of the 1MHz ripple current.

If you look at the 820μF/4V solid aluminum electrolytic capacitor in Figure 1-9, the ESR at 100Hz frequency is about 0.1Ω, and at 100kHz frequency it is about 0.01Ω. The difference between the two is 10 times, and the ripple current at 100Hz frequency is About 32% of the ripple current at 100kHz frequency. It should be noted that the characteristic curves in Figure 1-9 are products from 1995 to 2000. With the innovation of solid aluminum electrolytic capacitor manufacturing technology, the ESR at 100kHz frequency has also been significantly reduced. In 2020, 820μF/6.3V solid aluminum For electrolytic products, the ESR at 100kHz frequency can be reduced to 5~7mΩ, and the corresponding ripple current at 100Hz frequency is about 25% of the ripple current at 100kHz frequency. That is to say, using a highly conductive polymer as the negative electrode, under the same temperature rise conditions, the 100kHz ripple current capability of the solid aluminum electrolytic capacitor can be increased by nearly 4 times.

The ESR of liquid aluminum electrolytic capacitors changes greatly with temperature, even within an order of magnitude. The temperature characteristic curve of ESR of solid aluminum electrolytic capacitor is shown in Figure 1-10.Figure 1-10 ESR temperature characteristic curve of solid aluminum electrolytic capacitor

As can be seen from Figure 6-10, the ESR of solid aluminum electrolytic capacitors at a frequency of 100kHz basically does not change with temperature, similar to tantalum electrolytic capacitors.

4.2 impedance frequency characteristics

Solid aluminum electrolytic capacitors also have impedance frequency characteristics. Figure 1-11 shows the impedance frequency characteristic curves of solid aluminum electrolytic capacitors and liquid aluminum electrolytic capacitors in the 2021 product manual of Nantong Jianghai Capacitor Co., Ltd.

Figure 6-11 Impedance frequency characteristic curves of solid aluminum electrolytic capacitors and liquid aluminum electrolytic capacitors

In Figure 1-11, Z1 and ESR1 are the impedance frequency characteristics and ESR frequency characteristics of HPN 560μF/4V solid aluminum electrolytic capacitor, Z2 and ESR2 are the impedance frequency characteristics and ESR frequency characteristics of HEN 330μF/16V solid aluminum electrolytic capacitor, Z3, ESR3 is the impedance frequency characteristics and ESR frequency characteristics of AL-E 820μF/6.3V liquid aluminum electrolytic capacitor.

In the low frequency band (0.1~1kHz), the impedance of the electrolytic capacitor is dominated by the capacitive reactance of the capacitor, so the larger the capacitance, the lower the capacitive reactance. At this time, the liquid aluminum electrolytic capacitor with the largest capacitance (820μF/6.3V) shows the lowest impedance, the second largest capacitance (560μF/4V) solid aluminum electrolytic capacitor has the second highest impedance, and the highest impedance is the lowest capacitance 330μF. /16V solid aluminum electrolytic capacitor.

Because the ESR of liquid aluminum electrolytic capacitors is much greater than that of solid aluminum electrolytic capacitors. As the frequency increases, when the capacitive reactance of the liquid aluminum electrolytic capacitor decreases to the same order of magnitude as the ESR (above 5kHz in Figure 1-11), the ESR characteristics begin to gradually appear and are gradually higher than the capacitive reactance. At this time, the liquid aluminum electrolytic capacitor The impedance frequency characteristic begins to show flat characteristics.

At the same time, since the ESR of solid aluminum electrolytic capacitors is much smaller than that of liquid aluminum electrolytic capacitors, a higher frequency is required to reduce the capacitive reactance of solid aluminum electrolytic capacitors to the same order of magnitude as the ESR. It can be seen from Figure 1-11 that this frequency needs to be above 50kHz.

In the frequency band around 100kHz, the impedance characteristics of liquid aluminum electrolytic capacitors and solid aluminum electrolytic capacitors are both ESR characteristics. At this time, the capacitive reactance of the capacitor is much lower than the ESR. For example, the capacitive reactance of the 330μF capacitor with the lowest capacitance at the frequency of 100kHz is 4.8 mΩ, much lower than the ESR above 10mΩ.

As the frequency increases, the inductive reactance of the capacitor begins to increase to be close to the ESR, and the impedance characteristics of the capacitor begin to show inductive characteristics. Lead-pin solid aluminum electrolytic capacitors begin to exhibit inductive characteristics above 300kHz. The liquid aluminum electrolytic capacitor in Figure 1-11 has inductive impedance characteristics above 600kHz, which seems to have better high-frequency characteristics than solid aluminum electrolytic capacitors. In fact, the parasitic inductance of solid aluminum electrolytic capacitors is smaller than that of liquid aluminum electrolytic capacitors. The reason why liquid aluminum electrolytic capacitors exhibit inductive characteristics is that the ESR of liquid aluminum electrolytic capacitors is much higher than that of solid aluminum electrolytic capacitors. The inductance of the parasitic inductance needs to be close to the ESR. Or higher than ESR to show perceptual characteristics. If the ESR of the liquid aluminum electrolytic capacitor is 10 times that of the solid aluminum electrolytic capacitor and the parasitic inductance is the same, the impedance of the liquid aluminum electrolytic capacitor will be inductive and its frequency will be 10 times that of the solid aluminum electrolytic capacitor. Since solid aluminum electrolytic capacitors with the same rated voltage/capacitance are smaller and have smaller parasitic inductance, the frequency at which the liquid aluminum electrolytic capacitor in Figure 1-11 becomes inductive is not much higher than that of the solid aluminum electrolytic capacitor.

Entering the high frequency band (above 500kHz), the impedance frequency characteristics of each capacitor in Figure 1-11 all enter inductive characteristics. The capacitor impedance at this time will depend on the size of the capacitor’s parasitic inductance.

Although the impedance characteristics are inductive in the high frequency band, it does not mean that the capacitor does not have filtering characteristics. As long as the impedance is low enough, it still has good filtering characteristics.

The above is an analysis of the impedance characteristics of polymer electrolytic capacitor.

5 Polymer electrolytic capacitor – relationship between lead pin position and ESR

Since the negative electrode ESR of solid aluminum electrolytic capacitors is extremely low, the volume resistance of the aluminum foil cannot be ignored. For example, for a certain solid aluminum electrolytic capacitor, the ESR of products from different manufacturers may be quite different. Some are around 10mΩ, while others are around 8mΩ. If it is a liquid aluminum electrolytic capacitor, the ESR difference of 2mΩ seems to be negligible. After all, the ESR of the liquid aluminum electrolytic capacitor is much more affected by temperature than 2mΩ, and the ESR at room temperature is generally above 30mΩ.

The ESR of solid aluminum electrolytic capacitors almost does not change with temperature, and the ESR value is very low, which makes a difference of 2mΩ lead to a 20% difference in ESR. This difference is obvious in terms of application and durability of solid aluminum electrolytic capacitors. .

Under the same ripple current condition, the ESR increases by 20% to 30%, the capacitor loss increases by 20% to 30%, and the temperature rise will increase accordingly. Under the same temperature rise conditions, due to the 20% to 30% increase in ESR, the rated ripple current will be reduced by 10% to 14%. If the rated ripple current of a solid aluminum electrolytic capacitor is 5A, due to the increase in ESR, the actual ripple current capability will be reduced to 4.3~4.5A. This result is absolutely not allowed when the ripple current is applied to almost the limit state!

The reason for such an ESR difference is that the position of the guide pin is not at the center of the filter, but is offset to one side of the aluminum foil. Why should the guide pin be offset instead of centered? The reason is that the position of the guide pin of the electrolytic capacitor core should correspond to the position of the hole in the rubber plug. If the position of the core guide pin is inconsistent with the position of the hole in the rubber plug, the guide pin cannot enter the rubber plug. The guide pin must be offset to the foil side. In order to solve this problem, an offset guide pin appeared, which can solve the problem of offset position of the guide pin on the aluminum foil. The problem is that the guide pins are specially made, and the nailing and rolling machine needs to identify the “A” and “B” sides of the guide pins, resulting in an increase in the production cost of solid aluminum electrolytic capacitors using offset guide pins.

Based on the above problems, when the customer has no special requirements, the ESR is slightly higher using conventional manufacturing methods. If customers have higher requirements for ESR performance, offset guide pins and corresponding nailing and coiling processes are used to obtain the lowest possible ESR.

The above is an analysis of the relationship between the lead pin position and ESR of polymer electrolytic capacitor.

6 Polymer electrolytic capacitor – equivalent series inductance

Solid aluminum electrolytic capacitors have a much lower ESL than liquid aluminum electrolytic capacitors. The ESL of solid aluminum electrolytic capacitors produced from 1995 to 2000 is shown in Table 1-1.

As can be seen from Table 1-1, the ESL of solid aluminum electrolytic capacitors is significantly less than 10nH. The ESL of no more than 10nH is almost the length of the guide pin passing through the rubber plug and the parasitic inductance generated by the surrounding space, indicating that the negative electrode of the solid aluminum electrolytic capacitor is almost integrated.

Table 1-1 ESL of solid aluminum electrolytic capacitors

To further reduce ESL, solid aluminum electrolytic capacitors need to be in lamination form. The structure of laminated solid aluminum electrolytic capacitor is shown in Figure 1-12.

Figure 1-12 Cross-sectional view of laminated solid aluminum electrolytic capacitor

As can be seen from Figure 1-12, the electrodes of the laminated solid aluminum electrolytic capacitor are stacked, which eliminates the winding ESL of the wound electrolytic capacitor. The remaining ESL is only the terminal distance of the capacitor electrode. The physical inductance will be significantly lower than the ESL of the wound electrolytic capacitor. The impedance frequency characteristic curves of laminated solid aluminum electrolytic capacitors and wound solid aluminum electrolytic capacitors produced by the American CDE company before 2005 are shown in Figure 1-13 and Figure 1-14.

Figure 1-13 Impedance frequency characteristic curve of laminated solid electrolytic capacitor

Figure 1-14 Impedance frequency characteristic curve of chip solid aluminum electrolytic capacitor

The impedance frequency characteristics of the two specifications of laminated solid aluminum electrolytic capacitors shown in Figure 1-13 enter the inductive characteristics at a frequency above 2MHz. This ESL is determined by the physical size of the laminated solid aluminum electrolytic capacitor (length is 7.3mm).

The capacitors shown in Figure 1-14 are products before 2005. The size of the low ESR liquid electrolytic capacitor is ϕ8×10mm, and the size of the solid aluminum electrolytic capacitor is ϕ10×10.2mm. Therefore, liquid aluminum electrolytic capacitors may have a lower ESL than solid aluminum electrolytic capacitors. At high frequencies (above 10MHz), since the characteristic curve does not extend to 10MHz, the difference in ESL of the two electrolytic capacitors cannot be accurately judged.

The above is an analysis of the equivalent series inductance of polymer electrolytic capacitor.

7 Polymer electrolytic capacitor – ripple current

The biggest feature of solid aluminum electrolytic capacitors is that the ESR is greatly reduced, and at the same time, the ripple current allowed to flow is greatly increased.

The test conditions for the rated ripple current of solid aluminum electrolytic capacitors are different from the test conditions for the ripple current of liquid aluminum electrolytic capacitors. The test conditions for liquid aluminum electrolytic capacitors with a maximum temperature of 105°C are that the maximum core temperature is not higher than the ambient temperature 5°C, that is, the maximum core temperature is 110°C; the test conditions for liquid aluminum electrolytic capacitors with a maximum temperature of 85°C are that the core temperature is the highest The temperature is not 10℃ higher than the ambient temperature, that is, the maximum temperature of the core is 95℃.

The rated ripple current test conditions of solid aluminum electrolytic capacitors are: 105℃ products/125℃ products, the ambient temperature is ≤105℃, the temperature rise is not higher than 20℃; 125℃ products, 105℃≤ambient temperature ≤125℃ , the temperature rise is not higher than 5℃. Compared with the 85°C liquid aluminum electrolytic capacitor test condition, the maximum core temperature is not higher than the ambient temperature 10°C, which is a 20°C increase in temperature. This makes the solid aluminum electrolytic capacitor have a rated ripple current even under the same ESR conditions. It will also be larger than the liquid aluminum electrolytic capacitor. In addition, the ESR decreases sharply. The actual rated ripple current of the solid aluminum electrolytic capacitor with the same rated voltage and capacitance is at least 5 times higher, or even higher.

Table 1-2 shows the data of various aluminum electrolytic capacitors with the same capacitance (1000μF/16V).

Table 1-2 Data of various types of aluminum electrolytic capacitors of 1000μF/16V

In actual data, the ESR of the HEN type solid aluminum electrolytic capacitor reaches 10mΩ when the capacitance is 270μF, and the ripple current reaches 6100mA when the capacitance is 330μF.

Among low-ESR liquid aluminum electrolytic capacitors, CD285 is the model with the lowest ESR and the largest ripple current. The ESR is 38mΩ and the ripple current is 2000mA.

The general-purpose liquid aluminum electrolytic capacitor CD110 series has an ESR of 210mΩ at a frequency of 120Hz, and no ESR value at a frequency of 100kHz is given. The ripple current is 791mA (120Hz) converted to 950mA at 100kHz frequency.

Through comparison, it can be seen that solid aluminum electrolytic capacitors have ultra-low ESR and ultra-high ripple current tolerance capabilities that are unmatched by other types of electrolytic capacitors under high frequency conditions, and are especially suitable for high ripple current applications.

The above is an analysis of the ripple current of polymer electrolytic capacitor.

8 Polymer electrolytic capacitor- lifespan

8.1 Polymer electrolytic capacitor –the nature of failure of solid electrolytic capacitors

Since solid aluminum electrolytic capacitors have no electrolyte, there is no failure caused by the electrolyte drying out. There are two modes of solid aluminum electrolytic capacitor failure: short circuit and loss of capacitance.

Since the negative electrode of the solid aluminum electrolytic capacitor is a highly conductive polymer, which is in close contact with the aluminum oxide film of the positive electrode foil in a solid manner, the aluminum oxide film will break when exposed to external mechanical stress, resulting in a short circuit phenomenon, even if no power is applied when the film breaks. Since the breakdown field strength of the broken part is much lower than the breakdown field strength of the aluminum oxide film, once the solid aluminum electrolytic capacitor is powered on, it will cause irreversible breakdown of the broken part of the aluminum oxide film. Another kind of breakdown is that the solid aluminum electrolytic capacitor suffers from overvoltage. Once this overvoltage exceeds the breakdown voltage of the aluminum oxide film, even if it is a very short-term overvoltage breakdown, since the solid aluminum electrolytic capacitor does not have the ability to repair the aluminum oxide film, it will Overvoltage breakdown is an irreversible breakdown.

Another way solid capacitors can fail is through significant attenuation and loss of capacitance. The reason for the capacitance fading is the failure of the highly conductive polymer, and the failure form is the decomposition of the highly conductive polymer. The cause of the decomposition of highly conductive polymers is high temperature. When the temperature exceeds 125°C, the highly conductive polymers in solid aluminum electrolytic capacitors will decompose very quickly. Appropriately lowering the temperature can effectively slow down the decomposition rate.

8.2 life test conditions

The test conditions for judging the end of life of solid aluminum electrolytic capacitors take the 105°C/2000h HPN series of solid aluminum electrolytic capacitors from Nantong Jianghai Capacitor Co., Ltd. as an example.

8.2.1 High temperature load life test

At 105°C, with rated DC voltage applied, the end-of-life conditions are: capacitance decays to 80% of the initial capacitance, loss factor increases to no more than 150% of the initial value, ESR increases to no more than 150% of the initial value, leakage The current is lower than the specified value. There is no indication in this test that ripple current needs to be applied. This test condition must pass at least a rated life of 2000h.

8.2.2 High temperature storage life test

Temperature 60℃, humidity 90%~95%, no voltage applied. The end-of-life conditions are: the capacitance decays to 80% of the initial capacitance, the loss factor increases to no more than 150% of the initial value, the ESR increases to no more than 150% of the initial value, and the leakage current is lower than the specified value.

8.2.3 Welding heating resistance

Reflow soldering (260±5)℃, 10s, the capacitance change is not greater than ±5%, the loss factor is not greater than the initial value, the ESR is not greater than the initial value, and the leakage current after applying voltage is not greater than the specified value. The above are the performance requirements of chip electrolytic capacitors after reflow soldering. If they exceed these requirements, it can be determined that the electrolytic capacitor has failed after reflow soldering.

8.3 life characteristic curve

Generally, for every 20°C decrease in temperature, the life of solid aluminum electrolytic capacitors will increase by an order of magnitude, that is, for every 10°C decrease, the lifespan increases to 3.16 times the original value. Compared with liquid aluminum electrolytic capacitors, the lifespan increases to 2 times the original value for every 10°C decrease. Especially, the more the temperature decreases, the more obvious the lifespan increases.

Figure 1-15 shows a comparison of the estimated life of liquid aluminum electrolytic capacitors and solid aluminum electrolytic capacitors at 105°C/2000h.

As can be seen from Figure 1-15, when the temperature drops to 85°C, the life of the liquid aluminum electrolytic capacitor increases to 8000h, and the life of the solid aluminum electrolytic capacitor increases to 20000h; when the temperature drops to 65°C, the life of the liquid aluminum electrolytic capacitor Increased to 32000h (equivalent to 3.5 years), the life of solid aluminum electrolytic capacitors increased to 200000h (equivalent to 23 years).

During the durability test (HPN 560μF/4V), the changing trends of capacitance, loss factor, ESR, and leakage current are shown in Figure 1-16 to Figure 1-19.

Figure 1-15 Comparison of life estimation of liquid aluminum electrolytic capacitors and solid aluminum electrolytic capacitors

Figure 1-16 Capacitance change of solid aluminum electrolytic capacitor durability test

Figure 1-17 Dissipation factor changes in durability test of solid aluminum electrolytic capacitors

Figure 1-18 ESR changes of solid aluminum electrolytic capacitor durability test

Figure 1-19 Leakage current changes in durability test of solid aluminum electrolytic capacitors

8.4 accelerated life test

How do you know that the life of solid aluminum electrolytic capacitors increases by one order of magnitude for every 20°C decrease? How do you know that the life of solid aluminum electrolytic capacitors can reach 20 years at a temperature of 65°C? The most effective way to predict long-term life is accelerated life testing. Figure 1-20 shows Sanyo’s temperature acceleration test characteristic curve.

Figure 1-20 Sanyo’s temperature acceleration test characteristic curve

It can be seen from the accelerated life test that as the test temperature increases, the capacitance decay of the solid aluminum electrolytic capacitor accelerates. Calculated based on the capacitance attenuation of 20%, when the test temperature reaches 125°C, the capacitance attenuation of the 105°C product cannot support 2000h and can only be maintained for less than 600h. When the temperature rises to 135°C, the capacitance decay can only support 100h. If the temperature rises to 145°C, the capacitance decay can only be sustained for less than 20 hours. If the temperature rises to 155°C, the capacitance decay can only be sustained for less than 50 hours.

According to the rules in Figure 1-20, the life expectancy can be obtained.

In the formula, TA is the maximum ambient temperature; ΔT is the core center temperature rise caused by the actual ripple current; TO is the rated upper limit operating temperature; LO is the specified life when rated voltage is applied at the maximum temperature; LX is the actual operating temperature Estimated life under TA+ΔT.

The calculation method for the temperature rise ΔT due to internal heating caused by ripple current is:

In the formula, ΔTO is the maximum temperature rise when the rated ripple current is superimposed; IO is the rated ripple current (effective value); IX is the actual ripple current (effective value). The frequencies of IO and IX must be the same, and IX≤IO .

The above is an analysis of the life of polymer electrolytic capacitor.

9 Polymer electrolytic capacitor-the negative electrode is drawn from aluminum foil to carbon foil

Since the negative electrode foil of the aluminum electrolytic capacitor is the lead-out electrode of the negative electrode, the electrolytic capacitor is actually the capacitance between the positive electrode foil and the electrolyte solution and the capacitance between the negative electrode foil and the electrolyte solution connected in series, as shown in Figure 1-21.

The reason is that the negative electrode foil has a certain formation voltage, so the relationship between the negative electrode foil and the electrolyte must be a capacitor, not a direct electrical connection. The actual capacitance is the series connection result of two capacitors, that is

The capacitance of an ideal electrolytic capacitor should be the capacitance C1 between the positive electrode foil and the electrolyte or polymer.

Figure 1-21 Actual aluminum electrolytic capacitor

Since there is an aluminum oxide film on the negative electrode foil, and in some cases, a sufficient voltage is required due to the performance requirements of the capacitor, forming a capacitance C2 between the electrolyte or polymer and the negative electrode foil. According to equation (1-3), when C2 is infinite, C=C1, which is an ideal result.

Due to the existence of C2, especially when the size of C2 is close to C1, the actual capacitance C will be significantly attenuated. If C2=C1, the actual capacitance decays to 1/2 of C1; if C2=2C1, the actual capacitance decays to 2/3 of C1. Both of these results are relatively unacceptable, and the specific volume of the negative electrode foil needs to be increased as much as possible.

Usually, the specific volume of the low-voltage positive foil is in the range of 23 to 77 (25Vw/33Vw) or 36 to 118 (16Vw/21Vw), and the specific volume of the negative foil with a 3V formation voltage is about 150, where Vw is the operating voltage. Such negative electrode foil will cause the external capacitance of the capacitor to attenuate by more than 30% compared to the capacitance of the positive electrode foil. If there is direct conduction between the negative electrode foil and the highly conductive polymer, there will be no negative electrode foil specific volume, which will significantly reduce the volume of the solid aluminum electrolytic capacitor. Such negative electrode foil is carbon foil. The so-called carbon foil is to apply a layer of carbon on the surface of the corroded foil, and to ensure that there is as little oxide film between the carbon and the aluminum foil as possible, forming a direct connection between carbon and aluminum. The part of the aluminum oxide film that has not been removed can be treated with hydrocarbon-containing gas at high temperature for a long time after the aluminum foil is coated with carbon, so that the carbon reacts with the aluminum oxide film to form aluminum carbide, thereby destroying the aluminum oxide film and forming a direct connection between carbon and aluminum. .

After treatment, there is no capacitance between the negative electrode foil and the polymer, so that the capacitance of the solid aluminum electrolytic capacitor is effectively improved.

At the same time, increasing the specific volume of the positive electrode foil is also a way to increase the capacitance of the solid aluminum electrolytic capacitor. The specific volume of the positive electrode foil of the solid aluminum electrolytic capacitor is about 20% higher than that of the positive electrode foil of the liquid electrolytic capacitor with the same rated voltage.

The above is an analysis of the negative electrode lead of polymer electrolytic capacitor from aluminum foil to carbon foil.

10 Polymer electrolytic capacitor – things to note

When using solid aluminum electrolytic capacitors, in order to give full play to their performance with stable quality, the following points need to be paid attention to in circuit design.

10.1 Polymer electrolytic capacitor –polarity

Like other electrolytic capacitors, solid aluminum electrolytic capacitors have polarity. If the polarity is connected incorrectly, leakage current will increase during use or service life will be shortened. Therefore, in high-impedance circuits, coupling circuits, timing circuits (the capacitance changes that may be caused by changes in temperature will be beyond the scope of the circuit) and circuits that are greatly affected by leakage current (the voltage of each single capacitor in series may be due to The leakage current is inconsistent and cannot be equally divided) and should be prohibited from being used to prevent erroneous operating results.

10.2 Confirm rated performance

Confirm whether the application environment meets the application environment range given by the data. The main ones are: the terminal voltage cannot exceed the rated voltage, even for an instant; the applied temperature environment should be within the range given by the data, whether it is the highest temperature or the lowest temperature. must not exceed; the flowing ripple current must not exceed the rated ripple current, otherwise the inside of the capacitor will be overheated due to excessive current flowing through the ESR, reducing its service life.

10.3 limitations of applied voltage

Solid aluminum electrolytic capacitors above 25V will not cause problems if 100% of the rated voltage is applied; those of 25V and below are similar to tantalum electrolytic capacitors. When the ambient temperature exceeds 85°C, the voltage should be derated for use. When the temperature rises to 105°C, the voltage should be reduced. to 75%; the sum of DC voltage and ripple voltage shall not exceed the rated voltage; when the DC voltage is low, it should be noted that the reverse voltage caused by the ripple voltage shall not exceed 10% of the rated voltage; during the transition period such as cutting off the power supply and switching the power supply, The reverse voltage that occurs must not exceed 20% of the rated voltage, but Sanyo’s SVPD series must not apply reverse voltage.

10.4 limitations of charge and discharge current

Excessive inrush current generated by power-on or rapid charge and discharge due to other reasons may increase the leakage current of solid aluminum electrolytic capacitors or even cause internal short circuits. Therefore, when the peak impulse current exceeds 1A or exceeds 10 times the rated ripple current, a protection circuit should be used to improve the reliability of the circuit; a 1kΩ protection resistor must be connected in series when testing leakage current.

10.5 failure and service life

Please refer to the relevant data of each manufacturer for the failure rate when using solid aluminum electrolytic capacitors. Although the failure rate in use is very low, there is still the possibility of failure. Therefore, equipment using solid aluminum electrolytic capacitors is limited to cases where failure will not directly lead to casualties, etc., or where failure will not cause problems.

Typical failures of aluminum polymers are as follows.

10.5.1 Sporadic faults: Sporadic faults of solid aluminum electrolytic capacitors are mainly short circuit faults. For resin-encapsulated solid aluminum electrolytic capacitors, when a short circuit occurs, if the energizing current after the short circuit is small (ϕ10 is about 3A or less, ϕ6 is about 1A or less), although the solid aluminum electrolytic capacitor will generate some heat at this time, even if it is continuously powered, the appearance will be poor. There is no abnormality, but when the current exceeds the above value, the internal temperature of the solid aluminum electrolytic capacitor will rise. If the temperature reaches above 200°C, the organic semiconductor used as the negative electrode will melt and generate a large amount of gas. The internal pressure will rise, and the molten organic semiconductor will The odorous gas flows out from the gaps between the sealing material, the aluminum shell and the lead terminals. Do not bring your face or hands close to each other at this time to avoid burns. When a rubber-encapsulated solid aluminum electrolytic capacitor is short-circuited, if the energizing current after the short-circuit is small (ϕ10 is about 1A or less, ϕ8 is about 0.5A or less, ϕ6 is about 0.2A or less), the capacitor will generate some heat, and the appearance will not be abnormal when it is continuously energized. But when the current exceeds the above value, the internal temperature of the solid aluminum electrolytic capacitor will rise, the sealing material of the rubber product will be rolled, and the smell will leak out. At this time, the face and hands are also not allowed to be close to avoid burns. In fact, such solid aluminum electrolytic capacitors have expired and cannot be used anymore.

When using equipment equipped with solid aluminum electrolytic capacitors, if a short circuit occurs and odorous gas escapes, the power supply should be cut off; it generally takes several seconds to minutes from the occurrence of the short circuit to the occurrence of odorous gas. If a protection circuit is used, it should be followed Start designing during this time; when the generated gas enters the eyes or is inhaled into the mouth, rinse with water or gargle immediately; do not come into contact with the electrolyte of the solid aluminum electrolytic capacitor, and rinse with soap when the electrolyte adheres to the skin.

The electrolyte, electrolytic paper, plastic sleeve, packaging rubber, and base used in solid aluminum electrolytic capacitors are all flammable substances and are flammable. When the current after a short circuit is extremely large, in the worst case, clicking the terminal or the short-circuited part inside the capacitor may generate an electric spark, which can ignite the flammable material in the capacitor. Therefore, attention should be paid to the installation method, installation location and structural design of the capacitor.

10.5.2 Changes in electrical performance during use and failures due to service life: Similar to aluminum electrolytic capacitors, solid aluminum electrolytic capacitors will reduce their capacitance over time even if they are used according to the data given in the data sheet. Performance degradation such as ESR increase and ESR increase should be paid attention to during design. The life problem is mainly due to the deterioration of parameters such as large capacity and ESR after prolonged use, high temperature or high humidity for several hours, causing the negative electrode of the electrolyte to age and eventually appear in an “open circuit” state.

Solid aluminum electrolytic capacitors will increase leakage current due to reasons such as welding, storage, high temperature, and high humidity. Similar to aluminum electrolytic capacitors, they can be energized by applying a DC voltage to reduce the leakage current to the initial value. No matter what causes the leakage current to increase, this energizing method can be used to reduce the leakage current for qualified solid aluminum electrolytic capacitors. The change of leakage current during the charging process of solid aluminum electrolytic capacitor is shown in Figure 1-22.

As can be seen from Figure 1-22, the empowerment effect under high temperature is good and the time is short.

Figure 1-22 Leakage current changes during the charging process of solid aluminum electrolytic capacitors

When the ripple voltage frequency exceeds 500kHz, “compensation” measures should be taken to reduce the ripple current below the rated value.

It should be noted that since the ESR of highly conductive polymer electrolytic capacitor is much lower than other types of electrolytic capacitors, solid aluminum electrolytic capacitors should not be connected in parallel with other types of electrolytic capacitors because they will cause flow problems when connected in parallel due to the minimum ESR of solid aluminum electrolytic capacitors. The ripple current passed is the maximum.

Similar to tantalum electrolytic capacitors with liquid negative electrodes, solid aluminum electrolytic capacitors that have been deformed or dropped must not be used.

11 Polymer electrolytic capacitor – Problems raised about solid-liquid hybrid electrolytic capacitors

11.1 Polymer electrolytic capacitor -vibration issues

Solid aluminum electrolytic capacitors have very excellent performance, but they cannot be used in automotive electronic equipment. The reason is that after the solid aluminum electrolytic capacitor is subjected to vibration, the solid highly conductive polymer in close contact with the positive electrode foil may cause the aluminum oxide film to rupture, thereby causing the solid The aluminum electrolytic capacitor failed due to short circuit. Therefore, the instructions for use of solid electrolytic capacitors specifically state that vibration needs to be avoided during application.

Liquid aluminum electrolytic capacitors can have good anti-seismic performance by fixing the core and the shell relatively well. The reason is that the positive electrode foil in the liquid aluminum electrolytic capacitor is in close contact with the electrolyte, and the electrolyte will not damage the positive electrode foil during vibration. aluminum oxide film.

11.2 aluminum oxide film repair problem

The second problem with solid aluminum electrolytic capacitors is that since there is no electrolyte, they do not have the ability to repair the aluminum oxide film of liquid aluminum electrolytic capacitors. However, aluminum is a metal with very active chemical properties. If other metal impurities are present in the positive electrode foil, it will form a galvanic cell effect and even destroy the aluminum oxide film, leading to irreversible failure of the solid aluminum electrolytic capacitor.

If an electrolytic capacitor is manufactured that has the extremely low ESR and high ripple current tolerance of solid aluminum electrolytic capacitors as well as shock resistance and the ability to repair damaged aluminum oxide films, it will be compatible with solid aluminum electrolytic capacitors and liquid aluminum. The advantages of electrolytic capacitors are especially suitable for use in the field of automotive electronics, electrolytic capacitors that meet vehicle regulations with extremely low ESR, high ripple current tolerance, and anti-vibration capabilities. With the rapid development of automotive electronics, the demand for high-performance automotive grade electrolytic capacitors is increasing, and solid-liquid hybrid aluminum electrolytic capacitors have emerged.

11.3 the basic idea of solid-liquid hybrid aluminum electrolytic capacitor

Solid-liquid hybrid aluminum electrolytic capacitors can be thought of as polymerizing and breaking a highly conductive polymer outside the core, loading it with a solvent into the electrolytic capacitor core, and then evaporating the solvent to obtain a solid aluminum electrolytic capacitor core, and then impregnating the core with electrolytic liquid to form a solid aluminum electrolytic capacitor with electrolyte.

Problems that need to be solved: Carbon foil can be used as the negative electrode of solid aluminum electrolytic capacitors to eliminate the problem of specific volume of the negative electrode foil that causes the actual capacitance of the solid aluminum electrolytic capacitor to be lower than the capacitance of the positive electrode foil.
Carbon foil will not be suitable in liquid aluminum electrolytic capacitors, because the negative electrode of liquid aluminum electrolytic capacitors is ionically conductive, not electronically conductive. The ionic conductivity between the carbon foil and the electrolyte cannot be completed well, causing the carbon foil to be in the electrolyte. The specific volume is very low.

To obtain a solid-liquid hybrid aluminum electrolytic capacitor, you can go back to using aluminum foil as the negative electrode foil. The problem is that the capacitance of the capacitor is significantly lower than the capacitance of the positive electrode foil.

In order to solve this problem, people use titanium foil, that is, titanium oxide is coated on the negative electrode foil, and titanium oxide is used to connect the electrolyte and highly conductive polymer. Since titanium foil has a very high specific volume, laboratory tests can even reach 3000. Even if calculated as 1000 in actual applications, compared with the specific volume of the cathode foil of the order of 100, the resulting capacitance attenuation is negligible. In 2022, my country will be able to produce titanium foil for electrolytic capacitors.

12 Polymer electrolytic capacitor-solid-liquid hybrid capacitor performance analysis

Domestic solid-liquid hybrid aluminum electrolytic capacitors are mainly suitable for vehicle-mounted electronic equipment, so they need to be adapted to the vehicle voltage. They are generally in the voltage levels of 25V, 35V, 50V, 63V, and 80V. If the voltage is lower than 25V, it will not be suitable for vehicle-mounted electronic equipment.

In order to adapt to the requirements of automotive application environments, the operating temperature range of domestic solid-liquid hybrid aluminum electrolytic capacitors is -55~105℃ or -55~125℃. In order to adapt to the long life of the car, the solid-liquid hybrid aluminum electrolytic capacitor also needs to have a relatively long life, at least 5000h or longer.

Solid-liquid hybrid aluminum electrolytic capacitors have much lower ESR and high ripple current tolerance than liquid aluminum electrolytic capacitors. Table 1-3 shows the comparison of ESR and ripple current of different types of aluminum electrolytic capacitors.

Table 1-3 Comparison of ESR and ripple current of different types of 25V/330μF aluminum electrolytic capacitors

As can be seen from Table 1-3, the ESR of solid-liquid hybrid aluminum electrolytic capacitors is only 27% of the best-performing liquid aluminum electrolytic capacitors and 125% of solid aluminum electrolytic capacitors. The rated ripple current of solid-liquid hybrid aluminum electrolytic capacitors is 208% of liquid aluminum electrolytic capacitors and 54% of solid aluminum electrolytic capacitors.

Multiplication factor for ripple current. There is a highly conductive polymer negative electrode in the solid-liquid hybrid aluminum electrolytic capacitor, and the ripple current tolerance will be as sensitive to low-frequency ripple current as the solid aluminum electrolytic capacitor. Table 1-4 shows the ripple current frequency conversion coefficients of different types of 25V/330μF aluminum electrolytic capacitors.

Table 1-4 Ripple current frequency conversion coefficients of different types of 25V/330μF aluminum electrolytic capacitors

As can be seen from Table 1-4, solid aluminum electrolytic capacitors are the most sensitive to low-frequency ripple current tolerance, followed by solid-liquid mixed aluminum electrolytic capacitors, and liquid aluminum electrolytic capacitors are relatively least sensitive.
If the 120Hz frequency ripple current is 1 for comparison, Table 1-5 can be obtained.

Table 1-5 Ripple current frequency conversion coefficients of different types of 25V/330μF aluminum electrolytic capacitors

As can be seen from Table 1-5, highly conductive polymers make a huge contribution to the high-frequency ripple current withstand capability. Since most low-voltage applications are DC power supply bypass or output filtering of DC/DC converters, the ripple current The frequencies are all high frequencies, and there is almost no low-frequency ripple current of 100Hz or even 1kHz. Even if there is, its component will be very low. Therefore, improving the ESR and ripple current capability under high frequency conditions is the main development trend of low-voltage electrolytic capacitors.

Summarize:

Polymer electrolytic capacitors – performance analysis mainly includes a brief description of the manufacturing process of highly conductive polymer electrolytic capacitors, general electrical parameters of solid electrolytic capacitors, the relationship between guide pin position and ESR, lifespan and performance analysis of solid-liquid hybrid capacitors, etc. If you want to know more For more electrolytic capacitor products and knowledge, please click::http://xuansncapacitor.com

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