Widely used in all kinds of power electronic equipment DC-link part for DC support, energy storage filtering. In the inverter circuit, it is mainly used for smoothing and filtering the output voltage of the rectifier, absorbing the high amplitude pulsating current from the inverter to the DC-Link, and preventing it from generating high amplitude pulsating voltage in the DC support capacitor on the impedance of the DC-Link, so as to keep the voltage fluctuation on the DC bus in the permissible range.