分析比较了多种直流大电流测量方法，指出直流测量设备高压侧无源化是未来高压测量设备的发展趋势。针对传统块状玻璃型电流传感器传感头加工难度大、直流解调算法难以精确解调出法拉第旋转角的缺点，采用一种基于双光源双输出条形传感头的新型无源式直流电流传感器。这种结构降低了传感头制作及加工难度，在双通道光路、电路不对称的情况下，能够将与被测电流成正比的直流信号从直流本底光强信号精确解调出来。试验结果表明，在300 ~3 000 A范围内，测量准确度优于0.5%，在光功率波动达25.2%、双光路光功率不对称度为34.2%的情况下，双光源双输出传感器相对误差变化范围为-0.4% ~ +0.42%，远高于相同测试条件下单光源双输出传感器的性能。

Several kinds of direct current measuring techniques were analyzed and compared. It will be the developing trend of high-pressure current measuring equipments with passive sensing head. Traditional bulk-glass ring type current sensor has many difficulties in manufacturing massive sensing head and can’t demodulate Faraday rotation angle exactly if the light-path and electric-path of dual channel is asymmetric. In view of these shortcomings, this article adopted a novel passive strip-glass type current sensor with dual incident light sources and dual output path. This structure reduces the fabricating and processing difficulty of glass sensing head and can accurately demodulate Faraday rotation angle proportional to measured current from background light intensity signal. Result shows that the accuracy of studied direct current sensor is less than 0.5% within 300 A~3 000 A range. Even on the condition of 25.2% light power fluctuation and 34.2% asymmetric degree of the dual channel, the relative error varies from -0.4% to +0.42%. All data on the same test condition validates that passive strip-glass type current sensor with two incident light sources and dual output paths has better performance than traditional bulk-glass type current sensor.

国家自然科学基金项目(50377011)。