The Role of Film Capacitors in New Energy Vehicles

Film capacitors are a type of capacitor widely used in electronic products. They typically consist of metal foil as electrodes, overlapped and wound with plastic film materials such as polyethylene or polypropylene, forming a cylindrical structure. In operation, film capacitors store electrical energy through their electrodes. Compared to ordinary capacitors, they offer non-polarity, high impedance, excellent frequency characteristics, and low dielectric loss. In analog circuits, they are widely used because they help maintain signal quality and reduce distortion during transmission. In emerging fields, film capacitors are extensively applied in industries such as photovoltaics, wind power, and new energy due to their good safety and high voltage resistance.

Thanks to their excellent high-voltage tolerance, film capacitors are expected to benefit significantly from the future upgrade to 800V automotive platforms. When starting the motor and generator in electric vehicles, an inverter circuit is used to convert DC to AC. This circuit employs semiconductor switches such as IGBTs and SiC, and also requires corresponding capacitors to stabilize the high-voltage circuit.

Compared to other types of capacitors, film capacitors are better suited for high-voltage platforms. Unlike traditional consumer electronics, automotive electronics are critical to vehicle driving safety and may face harsher operating conditions, imposing stricter quality requirements. For example, components around the engine require a temperature tolerance of -40°C to 160°C, whereas ordinary consumer electronics typically operate between 0°C and 40°C. Moreover, automotive electronics have higher standards than consumer electronics in terms of humidity, mold resistance, corrosive gas exposure, and service life. This significantly increases the manufacturing complexity of automotive electronics and raises the bar for related enterprises. Compared to aluminum electrolytic capacitors, film capacitors offer higher temperature tolerance, can withstand higher voltages, and have a surge voltage resistance approximately 1.5 times their rated voltage. This makes them highly suitable for new energy vehicles, especially those with high-voltage platforms.

Film capacitors enhance the voltage withstand capability of electronic control systems. Since film capacitors are often used for DC support, they can absorb high-voltage pulse currents from the DC input terminal, thereby protecting power semiconductors and other components. Typically, each power semiconductor device is equipped with one film capacitor. In luxury vehicles that adopt multiple motors, the number of film capacitors used will increase accordingly.