单相直流侧串联型APF非线性平均电流控制

Nonlinear average current control of single-phase DC active power filters that are laterally connected in series

直流侧串联型APF采用PI平均电流控制时,在低频开关切换点存在着严重的电流畸变.该文分析了产生此电流畸变的原因,指出在低频开关点,高频开关的占空比需要发生跳变,而PI控制器不能实现占空比的跳变,这是造成此刻电流畸变的原因.非线性平均电流控制的控制特点是占空比直接参与控制,因此当系统占空比发生跳变时,该控制方法可以实现实际占空比的跳变.该文提出的将非线性平均电流控制应用到直流侧串联型APF中,解决了低频开关切换点的电流畸变问题.仿真结果证明了所提方法的正确性.

When a proportional-integral （PI） average current control scheme is applied to a DC side series active power filter （APF） input current displacement is a problem when the low frequency switch is turned on or off. After analysis of the essential causes of this current distortion it was found that the expected duty cycle of the high fre- quency switch needs to jump, but the output value of the PI controller cannot do so. As a result, the duty-ratio of the high frequency switch cannot jump; this inflexibility is the major reason for current distortion. The characteristics of a nonlinear average current control scheme are that the expected duty cycle is incorporated in the control. This control scheme can make the duty-ratio of the high frequency switch jump when the expected duty-ratio jumps. A DC side series APF based on a nonlinear average current control scheme was proposed that would resolve the in- put current displacement at the time the low frequency switch is turned on or off. These theoretical conclusions were verified by the results of a simulation.