基于LCL滤波的三相PWM整流器新型DPC策略

摘要

建立LCL滤波的三相脉宽调制(PWM)整流器的数学模型,对于直接功率控制(DPC)的开关频率不固定以及LCL滤波器引入的谐振问题,构造功率外环电流内环的双环控制结构;提出一种新型DPC策略,在功率环构造虚拟电压源等效为功率阻尼,同时功率环的输出作为电流环的输入指令值,电流环采用无差拍控制以保证电流跟踪精度,并采用空间矢量PWM(SVPWM)产生PWM信号驱动整流器功率开关,实现固定开关频率.仿真结果表明,该控制策略在抑制谐振的同时,实现整流器单位功率因数运行,系统具有较好的动静态性能.%A mathematical model of LCL-based three-phase pulse width modulation (PWM) rectifier is established.Considering the problems of unfixed switching frequency caused by direct power control (DPC) and the resonance problem of LCL filters,the two loops control system,an outer power loop and an inner current loop,is used to solve them.A new strategy of DPC is proposed.It is to construct virtual voltage source in the power loop which is equivalent to power damping,and at the same time make the output of power loop as the input instruction value of the current loop.The new DPC method uses deadbeat control in the current loop to ensure the current tracking accuracy,and takes the PWM signal caused by space vector PWM (SVPWM) to drive the power switch of the rectifier and achieve the fixed switching frequency.The simulation results show that the new DPC strategy can run the rectifier under unit power factor while effectively control resonance and ensure a better system with static and dynamic performance.