用于消除振动影响的光纤电流传感器结构

与传统电磁式电流互感器相比，基于法拉第效应的光纤电流传感器有许多明显的优点，因而获得了广泛的研究。光纤的固有双折射是影响传感器精度的主要原因，如何消除双折射也是研究的关键问题。这种双折射不仅与光纤本身的性能有关。还与工作时的环境温度、振动等因素有关。当传感头受到强烈振动时，所产生的机械应力将使传感光纤的固有双折射发生变化．影响输出光的偏振态．使传感器精度下降。提出了一种对称型的传感器结构．采用两套相同的光源及探测器．使传感光纤中形成传播方向相反的两束光．利用应力双折射的互易性补偿振动影响。实验表明．该结构可使传感器性能得到明显的改善．在10g的振动强度下．测量结果的线性度达到了二0．3％以下。

A Configuration of Optical Fiber Current Transducer for Elimination of Vibration Effect

Optical fiber current transducers based on Faraday effect have a lot of advantages over conventional current transducers and have been studied extensively. The intrinsic birefringence of the sensing fiber is the main cause which affects the measuring precision, and how to eliminate it is the key research topic. The birefringence is not only affected by the features of fiber itself but also is under the influence of environment factors such as temperature and vibration. When a optical fiber current transducer is intensely vibrated, the mechanical stress will change the intrinsic birefringence of the sensing fiber, affecting the output light state of polarization and deteriorating the measuring precision. In this paper a symmetrical transducer configuration with two identical light sources and photodiodes is presented. Two counter-propagating light beams are formed in the sensing fiber and stress-induced linear birefringence is compensated by its reciprocal nature. The experimental results show that this configuration can obviously improve the performance of the transducer and the signal linearity is achieved under ±0.3% with the sensor head exposed to a vibration level of acceleration 10 g.