LCL filter can effectively and economically ensure and improve the feed quality from energy to power grid. The progress of power semiconductor switching device technology has promoted the rapid development of power electronic converter technology. Various converter devices based on pulse width modulation (PWM) control have emerged, such as inverter power supply, inverter and other converters, and these converters have been widely used in various fields throughout the country. Three phase voltage source PWM rectifier has bidirectional power output and fast dynamic control response. The current PWM rectifier adopts IGBT as the power switching device, which can achieve a high switching frequency. Generally, the switching frequency is 2kHz~15kHz. However, the high turn on and turn off frequency of power switching devices will generate higher harmonics, which will be injected into the power grid and cause harmonic pollution. In order to solve the problem of LCL filter, we usually choose LCL filter. LCL filter can select smaller inductance and capacitance value to achieve satisfactory filtering effect between kilowatts and hundreds of kilowatts.