单相PWM整流器控制器设计与动态特性的改善

Design of the controller and improvement of the dynamic performance for single-phase PWM rectifiers

通过建立单相PWM整流器的数学模型,分析了电压外环采用PI控制器、电流内环采用比例谐振控制器的双环控制策略,并给出了电压外环PI控制器的设计公式。指出了比例谐振控制器因带宽小会导致系统稳定性降低,采用准比例谐振控制器则不仅可以增加带宽,还可以减小系统对电路参数及电网频率波动的敏感性。针对输出直流电压中二次纹波电压限制了电压外环带宽的问题,对比分析了3种在电压环控制器中抑制纹波电压的方法,提出了一种在比例积分滤波控制器上并联二阶陷波器的改进电压外环控制器。最后,仿真和实验验证了所提出方法的有效性和正确性。

The double loop control strategy with which proportional integral(PI)controller used in voltage loop and proportional-resonant controller used in current loop is analyzed by establishing mathematical model of the single-phase pulse width modulation(PWM)rectifier,and the design formula of voltage loop PI controller is given.The problem of proportional-resonant controller of current loop was system stability reduction due to the narrow bandwidth.The quasi-proportional resonant controller used increased the bandwidth,and reduced the sensitivity of the system to circuit parameters and grid frequency fluctuations.Second harmonic voltage in the output DC voltage limits the bandwidth of the voltage loop.Therefore,three ways of suppressing second harmonic voltage in voltage loop controller were compared and analyzed.A voltage outer loop controller which is parallel notch filter on the proportional integral filter controller was proposed.Its validity and feasibility are verified through simulation and experiment results.