中文说明：该模型由鉴相器、环路滤波器、压控振荡器器组成，在三相平衡下效果好 且跟踪速度快，具有较为实用的价值。该模型为本人在课题的一小部分，亲测可以用
English Description：
The model is composed of phase detector, loop filter and voltage controlled oscillator. It has good effect and fast tracking speed under three-phase balance, and has practical value. This model is a small part of my project, and can be used for personal test