基于光学电流互感器的低频高精度锁相环

针对低频区信号锁相所面临的精度低、稳定性差等缺点,提出了一种提高锁相精度的方法.以光学电流互感器测试系统为研究对象,设计了以CD4046为核心的锁相环电路,并对影响锁相精度的原因进行了研究.于被测信号进入锁相环之前,采用运放形成2次过零比较,克服了专用快速比较器产生自激振荡的同时,缩短了入锁信号的上升沿时间;设计了用于滤除工频噪声的二阶有源带通滤波器;将锁相环路中压控振荡器的固有中心频率进行了参数优化,使得2个输入的固有频差在理论上最小.结果表明,引入该锁相方法后的锁相精度由0.3%周期提高到0.03%周期(1°变为6'),并且锁相的稳定性和抗干扰性等其他性能指标都有了显著提高.

Low-frequency high-precision PLL based on optical current transducer

Aiming at the low - precision and instability of phase - lock in low - frequency area,a way is put forward to improve its precision.A PLL(Phase -Locked Loop) circuit with CD4046 as its core is designed for an optical current transducer test system and the factors affecting phase-lock precision are analyzed.Before the tested signal enters into PLL,two zero - crossing comparisons are carried out with operational amplifier to avoid the self-oscillation of the high-speed comparators and shorten the rising edge ...