Function and working principle of film capacitor

Film capacitors, also known as Plastic Film Capacitors, refer to capacitors with (electrical grade) plastic film as the dielectric. Compared with ceramic and electrolytic capacitors, it has the advantages of good product performance and high reliability, but the capacity/volume ratio is small and the price is high.

Film capacitor function:

The function of the film capacitor is the same as that of all capacitors, which is to hold the charge.

But compared to other general capacitors, film capacitors have many excellent characteristics, so they are a kind of capacitor with excellent performance. Its main characteristics are as follows: non-polarity, high insulation resistance, excellent frequency characteristics (wide frequency response), and low dielectric loss.

Among them, the capacitor of the type of metalized film has a so-called self-healing effect (Self Healing AcTIon), that is, when the tiny part of the electrode is short-circuited due to the fragile electrical boundary, it causes the electrode metal around the short-circuited part Due to the electrostatic energy or short-circuit current carried by the capacitor at that time, a larger area of melting and evaporation will be caused to restore the insulation, and the capacitor will resume the function of the capacitor. In other words, it can heal itself instantly.

Film capacitors are generally used for high-frequency filtering, high-frequency bypass, first-order or second-order filter circuits. It is widely used in electronics, home appliances, communications, electric power, electrified railways, hybrid vehicles, wind power, solar power and other industries.

Working principle of film capacitor:

The working principle of a film capacitor is the same as that of a general capacitor. It stores electric energy by storing charge on the electrode. It is usually used together with an inductor to form an LC oscillation circuit. The working principle of a capacitor is that the charge moves in an electric field. With a medium in between, it hinders the movement of charges and makes the charges accumulate on the conductor, resulting in the accumulation of charges.

The development of film capacitors:

The development direction of film capacitors is low cost, miniaturization, chip type, ultra-high voltage, high power, high precision, and high reliability. With the application and development of new materials and new process technologies, film capacitors will have major changes. With the development of complete equipment, the application of film capacitors will bring opportunities and challenges.