三相电压型PWM整流器控制特性

基于三相电压型PWM整流器的工作原理,研究了PWM整流器的四象限运行的工作状态,并在此基础上提出PWM整流器网侧呈现受控电流源、且电流和功率因数均可控的特性,这使得整流器可以灵活地在各种工作状态间切换。针对PWM整流器网侧功率因数控制的要求,指出PWM整流器需工作在升压状态,且推导出其保持正常运行时直流电压与交流输入电源电压的比值应大于一个临界升压系数。提出了基于空间矢量算法的PWM整流器阶段电流控制策略:升压系数较大时采用单位功率因数控制模式,升压系数较小时则切换至滞后功率因数控制模式。设计并搭建了基于DSP数字化的三相电压源型PWM整流器的物理平台,实验波形验证了PWM整流器自身运行特性与其工作在临界升压系数时电流控制策略的切换控制的正确性。

Control characteristic of three-phase voltage-source PWM rectifier

Based on the working principle of three-phase voltage-source PWM rectifier,its four-quadrant operating states are studied.It is concluded that,the grid side of PWM rectifier is presented as a current source with controllable current and power factor,which makes the PWM rectifier able to easily switch its operating state over from one to another.To meet the requirements of power factor control at grid side,PWM rectifier must work in Boost state,i.e.the ratio of DC voltage to AC input voltage should be greater than the critical step-up coefficient.The current control strategy of three-phase PWM rectifier is proposed based on space vector arithmetic:the unity power factor control mode when the step-up coefficient is bigger and the lagged power factor control mode when the coefficient is smaller.A hardware platform of three -phase voltage-source PWM rectifier based on DSP controller is designed and built up,and the experimental results validate its operating features and the correctness of the proposed control strategy.