光纤电焊电流测量技术研究

针对直流逆变电阻焊机焊接电流精确测量的需求,提出基于光纤电流传感技术的焊接电流测量方法。建立了光纤电流传感器闭环检测系统动态模型,通过优化系统的前向增益,提升了传感器响应速度和带宽。仿真和实验结果表明:传感器的上升时间约为4.1 μs,在DC~30kHz范围内幅频特性衰减小于0.3%。基于该动态模型计算传感器对焊接电流纹波分量的响应,仿真结果表明:系统的动态跟踪能力可满足对纹波电流的测量需求。利用等安匝法对光纤电流传感器进行校准,在直流5~50kA范围内,传感器的测量误差优于±0.05%。现场实验结果证明了光纤电流传感器用于直流逆变焊接电流测量及电焊电流测试仪现场校准的可行性。

Research on Fiber-optical Welding Current Measurement Technology

In response to the demand for accurate measurement of welding current of DC inverter resistance welding machines, a welding current measurement method based on fiber-optic current sensing technology is proposed.A dynamic model of the closed-loop detection system of a fiber-optic current sensor is established.By optimizing the forward gain of the system, the response speed and bandwidth of the sensor are both improved.The simulation and experimental results show that the rise time of the sensor is about 4.1 μs, and the amplitude-frequency characteristic attenuation is less than 0.3% over the range of DC to 30kHz.Based on the dynamic model, the sensors response to the welding current ripple component is calculated.The simulation results show that the dynamic tracking ability of the system can satisfy the measurement requirements of the ripple current.The fiber-optic current sensor is calibrated by the equal ampere-turn method, and the measurement error of the sensor is better than ±0.05% over the range of DC 5kA to 50kA.The field experiment results prove the feasibility of the fiber-optic current sensor using for DC inverter welding current measurement and field calibration of welding current tester.