调相式光纤电流传感器中传感头的设计

Design of Sensing Head in Phase-Modulating Fiber-Optic Current Sensor

在以压电效应为传感机理的调相式光纤电流传感器中 ,必须首先将电流信号转变为电压信号 ,再以此电压信号驱动压电陶瓷筒 ,使缠绕在筒上的光纤中光波的相位发生变化。一般采用低压电流互感器 (CT)实现电流—电压转换。这种方法由于CT本身的绝缘性不好 ,易出现磁饱和、转换电压不高等原因 ,使传感器的性能受到影响。文中提出一种新的传感头设计方法。它以Ro gowski线圈代替传统CT ,作为电流—电压转换装置 ,提高了传感器的精度。

In order to obtain the measured current,the phase-modulating fiber-optic current sensor must convert the current into phase variation first,then use the interferometer to detect the phase which is in proportion to current.One of the phase-modulating methods bases on piezoelectricity effect.This method must convert current into voltage,then use the voltage signal to drive piezoelectric cylinder to change the phase of the light wave which is transmitted in the fiber winding around the cylinder.Usually the current transducer (CT) is adopted to convert the current into voltage.But the conventional CT has some deficiency:poor insulation,magnetic saturation effect,low transform voltage,etc.These deficiencies reduced the sensor's performance.This paper presents a new method to design the sensing head of fiber-optic current sensor.It substitutes the CT by Rogowski Coil to finish the current-voltage transformation.Rogowski Coil has no magnetic saturation effect and is good at linearity.Its output voltage is high enough to drive the piezoelectric cylinder.So the accuracy,measurement range and reliability of the sensor are improved.