介绍了一种用于准互易光学电压互感器的数字闭环信号处理方法.根据互感器光路输出信号的特点,采用基于方波调制解调的数字相关检测技术,提高了系统的响应灵敏度.在此基础上,引入阶梯波反馈技术,通过相位调制器在两束相干偏振光间引入一个与晶体Pockels相移大小相等、方向相反的反馈相移,实现闭环检测,扩大了动态范围,且不依赖于传感晶体的半波电压.基于数字闭环信号处理方法的互感器在0～ 3000 V直流电压和0 ～4000 V 工频交流电压测试结果表明:互感器数字输出具有良好的线性关系；直流电压高于800 V时,互感器测量精度优于±0.89%,工频交流电压大于25 V和大于690 V时,互感器测量精度分别优于±0.44%和±0.2%.实验结果验证了该数字闭环信号处理方法的可行性.%A digital closed - loop detection scheme for the quasi - reciprocal optical voltage sensor ( OVS) is proposed and demonstrated in this paper. According to the characteristic of the interferometic signal, a digital correlation detection scheme based on square wave modulation and demodulation is applied to improve the sensitivity of OVS. By introducing a digital ramp feedback technology, a feedback phase shift between the two polarization beams is created to offset voltage induced Pockels phase according to the optical phase modulator. In this way, the closed - loop scheme is realized, which improves the dynamic range and independent on the half - wave of the sensing crystal. The experiments are implemented on the OVS with the proposed digital closed - loop detection scheme. The experiment results show that the DC voltage from 0 to 3000 V and 50 Hz AC voltage from 0 to 4000 V are measured with good linearity. The proposed OVS achieves accuracy within ± 1 % with the measured DC voltage above 800 V. And measurement accuracy is less than ± 0.44 % and ± 0. 2 % with the AC voltage above 25V and 690 V, respectively. The results verify the feasibility of the closed - loop scheme.
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