适于重复控制固定采样点数的数字锁相方法

针对基于重复控制策略的有源电力滤波器，提出一种基波周期内保持固定采样点数的数字同步锁相方法，推导基于同步旋转变换和PI调节的数字锁相闭环传递函数模型，表明为二阶系统.采用零极点配置方法对其进行控制参数的设计.该方法能够从原理上保证基波周期采样点数不变，满足重复控制策略的要求.给出应用此锁相方法的重复控制有源滤波器补偿效果波形，应证了数学建模和设计的正确性.结果表明，锁相环在电网畸变和不平衡条件下具有优异的鲁棒性和快速性，应用该锁相方法的有源滤波装置具有很高的补偿精度.

Digital PLL with fixed number of sampling points for repetitive control algorithm

To deal with the synchronization issue of a repetitive controlled active power filter (APF), a novel digital phase locked loop (PLL) strategy with fixed number of sampling points per cycle is present, which based on synchronous rotating frame phase detection (SRFPD) and PI controller. The mathematic model is developed in z-domain and proved to be a second-order one. By using zero-pole-placement method, control parameters are designed. This PLL guarantees the number of sampling points per fundamental period fixed theoretically and consequently meets with the requirement of sampling in repetitive control. Experimental results verify that the proposed PLL has good robustness and fast response even under distorted and/or unbalanced conditions; and corresponding APF bears high compensation precision.