一种用于局放测试的相频追踪系统

A phase frequency tracking system for PD testing

针对当前局部放电测试中同步信号的相频难以保持一致的问题,设计了一种用于局放测试的相频追踪系统。系统采用施密特触发器来对信号进行相位和频率的采集,克服了采用ADC进行数模转换时过零点持续电平难以采样的问题,通过1 MHz高频计数器的周期计数设置,确定了主从机延时算法,达到了相频追踪的目的。系统针对实际应用中所产生的相位漂移问题,通过统计计数器差值,找到了引起漂移的原因,设计了主从机处理方法,解决了相位偏移的问题,最后使得系统能稳定的追踪到1～500 Hz的同步信号全频带相频信息。

Aiming at the problem that the phase and frequency of synchronous signals is difficult to keep consistent in PD test,a new phase frequency tracking system for PD test is designed. The system uses Schmidt to trigger phase and frequency of signal acquisition;and overcome by ADC digital to analog conversion to zero level continuous sampling;and through cycle counting 1 MHz high frequency counter set,determine the master-slave delay algorithm;and achieves the purpose of tracking phase and frequency. Aiming at the phase drift problem in the practical application,the reason of the drift is found by counting the difference of the counter. And the master-slave processing method is designed to overcome the phase offset problem. Finally,the system can stably track the whole frequency band phase frequency information of 1～500 Hz synchronous signals.