本文讨论了基于二阶低通滤波器和基波正序分量提取的锁相技术，文中给出了详细的公式推导过程，用仿真和实验结果验证了该方法锁相的准确性，克服了传统方法的不足。
A phase locking technique is discussed in the paper based on the second-order low-pass filter and positive-sequence extraction of fundamental wave, the reference reasoning formula has been completed for the method. The accuracy of the PLL is demonstrated by simulation and experiment results, this method is better than the past method of phase locking.
