A film capacitor, also known as a plastic film capacitor, is a capacitor that uses a plastic film as the dielectric. The basic structure of a film capacitor consists of a metal foil as the electrode and a plastic film such as polyethylene, polypropylene, polystyrene, or polycarbonate, which is wound into a cylindrical structure by overlapping the two ends. Depending on the type of plastic film used, film capacitors are also known as polyethylene capacitors (also known as Mylar capacitors), polypropylene capacitors (also known as PP capacitors), polystyrene capacitors (also known as PS capacitors), and polycarbonate capacitors.

Features and Advantages

Film capacitors have a variety of excellent characteristics that make them one of the top performing capacitors. Its main characteristics include:

1. No polarity: Film capacitors do not need to distinguish between positive and negative poles, making them more convenient to use.

2. High insulation resistance: film capacitors have high insulation resistance, which can ensure the stability and safety of the circuit.

3. Excellent frequency characteristics: film capacitors have a wide frequency response and are suitable for a variety of applications such as high frequency and low frequency.

4. Small dielectric loss: film capacitors have small dielectric loss, which can ensure accurate signal transmission.

In addition, metallized film capacitors have self-healing characteristics, i.e., when a tiny part of the capacitor is short-circuited due to a defect that causes a breakdown, the metal film around the part will melt and evaporate over a larger area triggered by the electrostatic energy carried by the capacitor or the short-circuit current, which restores the insulation and enables the capacitor to regain its functionality.

Fields of application

Film capacitors are widely used in various electronic equipment due to their excellent performance, including but not limited to:

1. Power system: film capacitors play an important role in high-voltage direct current transmission (HVDC) and reactive power compensation devices, which can improve the voltage stability of the system, reduce voltage fluctuations, and improve the quality of power.

2. Communication equipment: film capacitors are widely used in filters, couplers, isolators and other devices because of their small size, light weight, good frequency characteristics and other advantages.

3. Automotive electronics: film capacitors play a key role in automotive electronic control units (ECUs), motor controllers, battery management systems, etc., and can improve the reliability and stability of the system.

4. Household appliances: film capacitors are widely used in air conditioners, refrigerators, washing machines and other high-power, high-frequency applications of home appliances because of their high voltage, high frequency characteristics and other advantages.

5. Industrial automation: in inverters, servo drives, robots and other equipment, film capacitors can improve the quality of the system's output waveform, reduce electromagnetic interference, and improve the stability of the system.