考虑直流侧CLC滤波的三相PWM整流器输出阻抗特性研究

PWM整流器能够实现AC/DC变换,既能为直流负载提供稳定的直流电压,又能控制交流侧电压电流同相位,实现单位功率因数;然而,一旦直流负载呈现负阻抗特性,系统可能出现震荡风险,影响系统稳定性.因此需要对其稳定性进行分析.CLC滤波电路对抑制三相PWM整流器直流侧纹波有一定作用,文中通过小信号建模方法推导出了考虑CLC滤波的PWM整流器直流侧输出阻抗,并通过扫频法验证了阻抗模型的准确性,并且分析了滤波参数、交流侧电感、电压外环比例系数和电压外环积分系数对阻抗的影响,当增大电压外环比例参数时,可以降低阻抗中频段幅值进而提高级联系统稳定性.

Research on Output Impedance Characteristics of Three-Phase PWM Rectifier Considering DC Side CLC Filter

PWM rectifier can realize AC/DC conversion,which can not only provide stable DC voltage for DC load,but also can control AC side voltage and current in the same phase,and realize unit power factor.However,once DC load presents negative impedance characteristics,the system may appear shock risk,affecting the stability of the system.Therefore,it is necessary to analyze its stability.CLC filter circuit plays a certain role in suppressing DC side ripples of three-phase PWM rectifier.In this paper,the DC side output impedance of PWM rectifier considering CLC filter is derived by small signal modeling method,and the accuracy of impedance model is verified by sweep frequency method,and the influence of filtering parameters,AC side inductance,voltage outer loop proportional coefficient and voltage outer loop integral coefficient on impedance is analyzed.When the proportional parameters of the voltage outer loop are increased,the amplitude of the middle frequency band of the impedance can be reduced and the stability of the cascade system can be improved.