PWM整流器一般不平衡分析和控制策略研究

Analysis and control of PWM rectifier under general unbalanced condition

针对一般不平衡状况下脉冲宽度调制(PWM)整流器电网电流质量差的问题,在正、负序电流和直流电压双闭环控制方案的基础上,提出了解耦的复矢量电流PI控制器设计方法。首先建立了一般不平衡的PWM整流器复矢量数学模型,计算了系统的有功和无功功率脉动,并以网侧高功率因数和直流电压稳定为控制目标,在复矢量模型的基础上分析了正、负序电流环路控制器的设计方案,并论证了电流控制环路的稳定性及其对系统硬件参数的适应性。最后构建了一般不平衡状况下10 k W的PWM整流器仿真和实验平台,对所提出控制策略的正确性进行了仿真和实验验证。结果表明,基于解耦的复矢量PI控制的整流器动、静态性能有明显优势。

In order to solve the problem of poor current quality of PWM rectifier under general unbalanced conditions, a decoupled design method of complex vector current PI controller is proposed based on the dual closed-loop control scheme of positive and negative sequence currents and DC voltage control. Firstly, the complex vector mathematical model of general unbalanced PWM rectifier is established and instantaneous active and reactive power are introduced in detail. Then, the design method of decoupling complex vector current PI controller is proposed for high power factor and stable DC voltage. The stability of the controller and the adaptability to the parameters of the PWM rectifier are demonstrated. Finally, the simulation and experimental platform of a 10 kW PWM rectifier under general unbalanced condition is constructed, the validity of the proposed control strategy is verified by simulation and experiment. The results show that the performance in both dynamic and steady state of the rectifier has obvious advantages by the use of the decoupled complex vector PI control method.