MIXED TRANSFORMATION SYSTEM BASED ON THREE-PHASE PWM RECTIFIER AND MULTI-UNIT UNCONTROLLED RECTIFIERS AND CONTROL METHOD THEREFOR

摘要

A mixed transformation system based on a three-phase PWM rectifier and multi-unit uncontrolled rectifiers. The mixed transformation system mainly consists of three-phase electric reactors (L), a three-phase voltage type PWM rectifier module, an N-unit three-phase uncontrolled rectifier bridge module group, capacitors (C0-CN) and a DSP control circuit. An input end of the three-phase voltage type PWM rectifier module is connected with input ends of all the three-phase uncontrolled rectifier bridge modules in parallel. The three-phase voltage type PWM rectifier module can carry a load or no load, and the three-phase voltage type PWM rectifier module just does reactive power compensation when no load is carried. All modules of the three-phase uncontrolled rectifier bridge module group can carry loads independently or can carry the same load by connecting all outputs in parallel. The mixed transformation system has the advantages of unit input power factors, low-harmonic and large-power output of grid-side current, low cost, simple control and the like.