基于调制解调法的直流光学电流互感器中解调方法的研究

his paper presented the signal to noise characteristics of optical direct current transformer base on Faraday Magneto-optical effect and the application of modulation and modulation and demodulation method, and analyzed the principle of modulation and demodulation in frequency domain. A theoretical analysis was made on the anti-noise performance of envelope detection method and synchronous demodulation method. This paper pointed out that, when the noise is small and the bandwidth of bandpass filter is narrow, the anti-noise performance of these two demodulation methods is almost the same. But, under other conditions, synchronous demodulation method is superior to envelope detection. The measurement accuracy of envelope detection and synchronous demodulation method was simulated and analyzed under different bandwidth of band-pass filter in LabVIEW. The simulation results showed that when only measuring DC component, the two demodulation methods had the same accuracy, but when measuring harmonic current as well, synchronous demodulation method was superior to envelope detection method.