Whether the capacitor is a live wire or a neutral wire

Capacitor technology trend under the development of new energy vehicles

Any hardware circuit is inseparable from the basic passive components, and capacitors are also indispensable in new energy vehicles. In general, its role is nothing more than filtering, absorption and resonance. But it is these basic functions that help build the core electronic control system of new energy vehicles.

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The "new energy" road of ceramic capacitors

When it comes to capacitors, probably most people's first reaction is a common component like a "screw". But since 2021, capital has seen the possibility of rapid growth in this segment: In the primary market, Shanghai Yingfeng Electronics, a leading subdivision enterprise, completed two consecutive rounds of financing this year, and its valuation rose sharply; In the secondary market, relevant listed companies are also expanding production in a big way. Among them, Farad electronic automotive film capacitors will be expanded by 100% in 2021, and another 100% is planned to be expanded in 2022; Jianghai film capacitors have not only entered a large number of applications in consumer electronics and industrial equipment, but also began mass delivery in the field of new energy electric vehicles and military industry, and the production of automotive film capacitors will also be expanded by 70-80% in 2022. Ceramic capacitors: capacitors with ceramic as dielectric materials, there are many branches of such capacitors, including various packages and withstand voltages, in which the internal dielectric materials are also divided into ferroelectric ceramics, barium titanate, talc and other materials, and then use pyrolysis and other methods to make an outer wrapped electrode. Ceramic capacitors have no polarity, ceramic capacitors with wires generally have high withstand voltage, and are used in high-voltage occasions with safety requirements; The most widely used is the chip multilayer ceramic capacitor (MLCC), which has the characteristics of small size, low price, high specific volume and high precision, and can be applied to high frequencies, but the material is brittle and the relative capacity is low. Representative companies: Fenghua Hi-Tech (000636), Sanhuan Group (300408), etc. According to the data of the China Electronic Components Industry Association, ceramic capacitors accounted for more than 50% of the global capacitor market in 2019 due to their wide range of application fields and high cost performance, followed by aluminum electrolytic capacitors (accounting for more than 30%), film capacitors and tantalum electrolytic capacitors accounted for less than 10%. Compared with other capacitors, film capacitors have the advantages of excellent high temperature and high pressure resistance, good reliability, long life, and overvoltage self-healing ability. In various frequency conversion and AC/DC conversion scenarios, such as electric drives, OBCs, charging piles of new energy vehicles, as well as inverters and converters of photovoltaic and wind power, film capacitors are widely used.

What are the uses of ceramic capacitors?

Class 1: Small temperature coefficient, suitable for tuning circuits and circuits that require compensation effects. Class 2: High dielectric constant, suitable for bypassing, coupling, DC blocking and filtering circuits. Class 3: large capacity, small size, low voltage. Used for filtering, bypassing, coupling circuits. AC: Anti-electromagnetic interference. High-frequency ceramic capacitors (Class I porcelain dielectric capacitors): good capacity stability, small dielectric loss, high insulation resistance, but small capacity; It is mainly used in high-frequency circuits and high-frequency high-voltage circuits in electronic equipment. (e.g. secondary output rectification of computer motherboard and switching power supply) Low-frequency ceramic capacitors (Class II ceramic dielectric capacitors): refers to capacitors with ferroelectric ceramics as dielectrics, Class II ceramic dielectric capacitors have small capacitance, large capacity, but poor stability and large loss. It is mainly used for low-frequency bypass, DC blocking, and filter circuits. (e.g. filtering after AC rectification)

What are the temperature characteristics in ceramic capacitors?

It refers to the rate of change of capacitor capacitance relative to normal temperature within the specified temperature range. For example, NP0, in the temperature range of -25 °C - +85 °C, relative to 25 °C, the allowable change in capacitance is less than 60ppm for every 1 °C change in temperature. For example, Y5P, in the temperature range of -25 °C to +85 °C, the rate of change in capacity relative to 25 °C is allowed to ± 10%. Code: Y: -25 °C; 5：+85 ℃ Rate of change: P: ±10%; U：+22%，-56%； V：+22%，-82%。

How many types of capacitors there are

1. Ceramic capacitors Ceramic capacitor is a common capacitor, and its dielectric material is ceramic. It has the advantages of small size, large capacity, high precision and good stability. Ceramic capacitors are widely used in filtering, coupling, maintenance and other aspects in electronic circuits. 2. Aluminum electrolytic capacitors Aluminum electrolytic capacitors are polar capacitors whose positive electrode is made of pure aluminum foil. Aluminum electrolytic capacitors have the advantages of large capacity, small size, long service life and stable operation, so they are widely used in filtering, coupling, maintenance and other aspects in electronic circuits. 3. Electrolytic capacitors An electrolytic capacitor is a capacitor composed of two metal foils, and its dielectric material is an electrolyte. The advantages of electrolytic capacitors are large capacity, small size, stable capacitance, but their polarity is obvious, can only be used in DC circuits, and the electrolyte inside the capacitor is easy to dry and leak. 4. Organic electrolytic capacitors Organic electrolytic capacitor is a new type of capacitor, and its dielectric material is organic polymer material. The advantages of organic electrolytic capacitors are small size, large capacity, long service life, stable operation, good temperature stability and other characteristics, and are widely used in high-frequency circuits. 5. Film capacitors A film capacitor is a capacitor that uses a metal foil and film as electrodes. Its advantages are high precision, good stability, and good frequency characteristics, so it is widely used in high-frequency circuits. 6. Metallized polyester film capacitors A metallized polyester film capacitor is a capacitor that uses a polyester film as a dielectric and a metal foil or metal-coated film as an electrode. It has the advantages of small capacity, small size and stable work, and is widely used in electronic circuits. 7. Metallized polypropylene film capacitors Metallized polypropylene film capacitor is a capacitor that uses polypropylene film as a dielectric and metal foil or metal coated film as an electrode. Compared with metallized polyester film capacitors, metallized polypropylene film capacitors have a larger capacitance, a longer service life, and are not easy to damage and have a long service life. 8. Glass capacitors A glass capacitor is a capacitor made of metal foil and glass as a dielectric. It is characterized by high precision, good stability and small capacity, and is widely used in precision circuits. 9. Varactor diodes A varactor diode is a diode that can change the value of the capacitor. Its capacitance value can be achieved by changing the reverse voltage. It is widely used in radio tuning circuit, oscillation circuit and other aspects. 10. Piezoelectric capacitors A piezoelectric capacitor is a component that uses the piezoelectric effect to achieve capacitance. The advantages of piezoelectric capacitors are large capacity and high precision, and are widely used in mechanical vibration sensors, pressure sensors and other aspects. In short, there are many types of capacitors, and different types of capacitors have different characteristics and application fields. When selecting capacitors, it is necessary to select the appropriate type of capacitors according to specific usage requirements and application scenarios.

What is the difference between ceramic capacitors and film capacitors

Ceramic capacitors and film capacitors are two common capacitors. The main differences between them are as follows: 1. Structure: Ceramic capacitors are composed of ceramic dielectric and metal electrodes, while film capacitors are formed by coating a metal film on an insulating substrate. 2. Capacity value: The capacity value of ceramic capacitors is usually higher, while the capacity value of film capacitors is lower. This is because the structure of the ceramic capacitor enables a large electrode area, which increases the capacity value. 3. Accuracy: Film capacitors have higher accuracy and can achieve smaller tolerances. Ceramic capacitors have relatively low accuracy and large tolerances. 4. Temperature characteristics: The temperature characteristics of ceramic capacitors are poor, and the capacity value will change greatly with the change of temperature. The temperature characteristics of the film capacitor are better, and the change in capacity value is relatively small. 5. Cost: Generally, the cost of ceramic capacitors is lower, while the cost of film capacitors is higher. In summary, ceramic capacitors and film capacitors differ in structure, capacity value, accuracy, temperature characteristics and cost. The choice of which capacitor to use is based on the specific application needs and performance requirements.