基于状态反馈与重复控制的逆变器控制技术

State-feedback-with-integral Control plus Repetitive Control for PWM Inverters

针对PWM电压型逆变器提出了一种将带积分状态反馈与重复控制相结合的输出电压控制方案。状态反馈所需的变量为电容电压和电容电流。为避免采样、计算延时占用 PWM脉宽,以上反馈变量值均由状态观测器基于实测电容电压和负载电流值预测得到,使控制算法可以提前一拍进行,这样也避免了设置专门的电容电流传感器。由于积分控制的引入,改善了状态反馈控制的稳态精度,克服了早先提出的类似方案在加载时的电压跌落问题。居于控制系统最外层的重复控制器可以保证逆变器即使带非线性负载也能保持高度正弦的输出电压。实验表明该方案可同时实现高动态响应和高稳态波形精度,适用于UPS等需要高性能输出电压控制的场合。

A new control scheme incorporating state- feedback-with-integral control and repetitive control is proposed for PWM voltage source inverters （VSI）. The state variables to be fed back are output voltage and capacitor current. To prevent the available pulse width from been affected by sampling time and the execution time of the control algorithm, a state observer is employed to predict the values of those state variables based on the sensed values of output voltage and load current. By doing so the state observer also relieves the need for a capacitor current sensor. Introduction of integral control into the state feedback reduces the steady-state error. Therefore it eliminates the voltage droop phenomenon associated with a similar hybrid control scheme proposed earlier. A repetitive controller is placed on the outmost layer of the control system, which improves output voltage waveform with nonlinear load. Experiments show that the proposed control scheme can achieve high-dynamic response and near perfect output voltage waveform. This control scheme is best suited for UPS applications where high performance voltage control is needed.