基于二自由度PID的三相PWM整流器调压改进策略

基于前端电压源型整流器(voltage source rectifier，VSR)与后端电压源型逆变器(voltage source inverter，VSI)级联的VSR-VSI双三相脉冲宽度调制(pulse width modulation，PWM)变换器已在电梯能量回馈系统中得到广泛应用，但前端三相VSR采用传统比例积分(proportional integral，PI)双闭环控制结构通常存在中端直流母线电压无法兼顾抗干扰性和跟踪性的问题。为此，文中提出一种基于二自由度比例积分微分(proportional integral differential，PID)的三相PWM整流器调压改进策略。首先，阐述基于VSR-VSI双三相PWM变换器级联系统的结构和工作原理，并给出前端三相VSR的传统PI双闭环控制方案及其参数设计过程，分析该方案不能兼具良好的抗干扰性与跟踪性的原因。在此基础上，给出基于二自由度PID的前端三相VSR直流调压优化策略及其参数设计方法。最后，利用软件仿真与实验测试对比结果共同验证了所述三相PWM-VSR直流调压改进策略的有效性与优越性。

An optimization strategy for voltage regulation of three-phase PWM rectifier based on two-degree-of-freedom PID

The VSR-VSI dual three-phase pulse width modulation (PWM) converters based on the cascade connection of a front-end three-phase voltage source rectifier (VSR) and a back-end three-phase voltage source inverter (VSI) have been widely used in elevator energy feedback systems,but the front-end three-phase VSR using the traditional proportional integral (PI) double closed-loop control structure usually has the problem that the mid-end DC voltage cannot take into account the disturbance immunity and the follow-ability. Given this,an improved DC voltage regulation strategy of the three-phase PWM rectifier based on two-degree-of-freedom proportional integral differential (PID) is proposed. Firstly,the structure and working principle of the three-phase VSR-VSI dual three-phase PWM converters are expounded. Then,the PI double closed-loop control scheme of the front-end three-phase VSR and its parameter design process are given to analyze the reasons why this traditional scheme cannot have good disturbance immunity and follow-ability of the DC voltage regulation system. On this basis,an optimized DC voltage regulation improvement strategy for the front-end three-phase VSR based on two-degree-of-freedom PID and its corresponding parameter design method are given. Finally,the correctness and the superiority of the proposed three-phase PWM-VSR DC voltage regulation strategy are verified by using the simulation and experimental comparison results.