比较式光学电流互感器的信号解调

长期稳定性是光学电流互感器(OCT)实用化的关键问题之一.比较式OCT在传统OCT的基础上,引入永磁体产生的恒定磁场作为参考磁场,通过将被测电流磁场与参考磁场相比较得到最终的电流测量结果,实现了对光学传感头的Verdet常数和线性双折射的同时补偿,使OCT的实用成为可能.针对新的传感头结构,设计了全新的双光源双输出信号解调方式以及基于此原理的信号解调系统.初步的线性度试验结果验证了该解调方式的正确性,同时也表明所设计的比较式OCT满足IEC标准规定的0.2级电子式电流互感器的精度要求.

Signal Demodulation of Comparative Measurement Based Optical Current Transformer

The lack of long-term stability has all along been baffling the popularization of the optical current transformer (OCT). Based on the conventional OCT, comparative measurement OCT introduces an invariant magnetic field generated by a permanent magnet as the reference source. The final current value is obtained by comparing the current magnetic field with the reference one, realizing compensation for both the invariance of Verdet constant and linear birefringence at the same time and making the application of the OCT in industry a reality. In view of the new sensor structure of the comparative measurement based OCT, a brand new signal demodulating method of dual-source and dual-output is designed. The linear test results show that the signal demodulation is valid and that the accuracy of the OCT proposed is up to the 0.2 class accuracy requirement in IEC60044-8.