Precharge soft starting circuit for three-phase voltage type bi-directional PWM current transformer

A precharge soft starting circuit for a three-phase voltage type bi-directional PWM current transformer comprises a first contactor K1, a three-phase diode rectifier bridge TM, a BUCK-BOOST circuit, a second contactor K2 and a DSP, wherein a three-phase alternating voltage source is connected with the alternating-current side of the three-phase diode rectifier bridge TM through the first contactor, the direct-current side of the three-phase diode rectifier bridge TM is connected with the BUCK-BOOST circuit, the BUCK-BOOST circuit is connected with the second contactor K2, the second contactor K2 is connected with the two sides of a direct-current end bus capacitor, and the first contactor K1, the controlled end of the BUCK-BOOST circuit and the second contactor K2 are all connected with the control end of the DSP. Current surge in the starting process is effectively avoided, so that service life is prolonged. 种适用于三相电压型双向PWM变流器的预充电软启动电路，所述软启动电路包括第接触器K1、三相二极管整流桥TM、BUCK?BOOST升降压电路、第二接触器K2和DSP处理器，三相交流电压源通过第接触器与三相