对内层控制采用PWM控制的有源电力滤波器 (active power filter,APF),当检测部分采用2步预测修正时,在负载较重时能够取得较好效果,但在负载较轻时 APF 的补偿效果较差.该文对其产生机理进行分析,指出 APF 系统满足鲁棒稳定性与满足干扰抑制性能对控制增益的要求是矛盾的,在负载较轻时要想取得较好的控制效果往往需要较大的控制增益,使矛盾更加凸显.为进一步提高 APF 的补偿效果特别是轻载下时,提出嵌入预测控制,将 APF 系统化成无时滞的系统,从而扩大了满足系统鲁棒稳定性的控制增益的取值范围.在此基础上,考虑实际中传感器可能受到的噪声的影响,采用鲁棒H2/H∞混合控制的方法设计控制器增益使得系统在参数摄动、随机干扰、死区干扰等影响下依然能取得较好的效果.最后,通过仿真实验和物理实验证明了所做分析的正确性和所提方法的有效性.
For the active power filter (APF) using pulse width modulation (PWM) controller as inner layer controller, if its detection part is corrected by two step forecast, the compensation effect is good under heavy load but still bad under light load. The mechanism is analyzed which proves there is contradictory between the robust stability and disturbance rejection, and the contradictory get worse under light load because it needs a bigger control gain. In order to improve the compensation effect of APF especially under light load, the predictive control is embedded in to turn the system to a no time-delay one so that the range of controller gain which can make the system stability is expanded . On this basis, the controller gain is designed by robust H2/H∞ control strategy to achieve better results under the influence of system parameter perturbation, random noise and the dead time zone .Finally, simulation and physical experiments was designed to verify the effectiveness of the design proposed in this paper.