复数滤波器型锁相环的改进控制策略

An Improved Control Strategy of Complex-Coefficient-Filter-Based PLL

将复数滤波器(CCF)应用于锁相环(PLL)是一种新型的电网同步技术。为进一步提高CCF-PLL的动态性能,提出了一种可增大系统相角裕度的改进算法。该控制策略是将输出角频率的单位反馈改为其比例项和积分项分别进行线性反馈。积分项的单位反馈保证了系统的准确性,比例项的线性反馈可调节相角裕度、改善动态性能。研究发现,所提PLL的相角裕度可达45°,动态指标大幅提升。最后进行了仿真和实验验证,结果表明:相比CCF-PLL,所提PLL在电网变化时各输出量的超调更小、动态品质更佳。

Using complex coefficient filter(CCF)to study phase-locked loop(PLL)is a new grid synchronization technique. An improved control method which can increase the phase margin is put forward to further improve the dynamic performance of the CCF-PLL. The control strategy changes the unit feedback of the output angular frequency to linear feedback of the proportional term and integral term respectively. The unit feedback of the integral term ensures the system stability. The linear feedback of the proportional term can adjust the phase margin and improve the dynamic performance. The study shows that the phase margin of the proposed PLL can reach 45° and therefore the dynamic index is greatly improved. Finally, the simulation and experiment are carried out and the results show that compared with CCF-PLL,each output of the proposed PLL has lower overshoot and better dynamic behavior when power grid changes.