Analysis and Suppression of Common Mode Interference in Three- Phase Power Rectifier Unit Based on Common Mode Transformer

Power rectifier unit can realize converting current by use of three-phase synchronous rectification bridge. The multiple parallel power units can amplify the capability of single generator and it is invaluable in battery charge, welding machine and electrochemistry fields. Nevertheless, the electromagnetic interference (EMI) which results from the speedy switch of power devices would affect the parallel output voltage, even out of control. According to the structure of power rectifier unit in this paper, the current path and magnitude of common mode (CM) conducted interference which ranges from 10kHz to 30MHz would be more analysed. The simulation model with parasitic parameters based on SPWM control model was built in this paper and then contrasted the different suppression methods by use of inductor and transformer respectively. At last, the line impedance stability network (LISN) and EMI receiver were used to test the common mode interference (CMI) of power rectifier unit. The experiment result verified the accuracy of model and validity of suppression method with CM transformer. Key-Words: Electromagnetic Interference, Common Mode Transformer, Conducted Interference, Power Rectifier Unit, Line Impedance Stability Network.