基于隧道磁阻磁场传感器的断路器弧后电流测量

Post-arc Current Measurement Based on TMR Magnetic Field Sensor

为实现断路器开断过程弧后电流的非接触式测量,提出基于阵列式隧道磁阻(tunnel magnetoresistance,TMR)磁场传感器的弧后电流测量方法。首先以TMR磁场传感器为核心设计搭建电流测量装置,在50 Hz交流电电路中验证方案的可行性和精度;之后搭建断路器合成回路实验装置并进行弧后电流测量,获得各TMR磁场传感器的电压变化曲线,根据电压与电流的对应关系反推出电流变化曲线,并对比前人研究测得的弧后电流波形,两者变化趋势一致,数值数量级相同,佐证了测量结果的可靠性。实验结果表明:TMR磁场传感器能实现交流电流的测量,频率响应及时,误差在±7%以内,电流数值与TMR磁场传感器离电流的距离相关,最小可测得90 mA。

In order to realize the non-contact measurement of the post-arc current during the breaking process of the circuit breaker,this paper proposes a post-arc current measurement method based on the array tunnel magnetoresistance(TMR)magnetic field sensor.In this regard,a current measurement device was designed and built with the TMR magnetic field sensor as the core,and the feasibility and accuracy of the scheme were verified in the 50 Hz AC circuit.The circuit breaker synthetic circuit experimental device is set up,the post-arc current is measuremed and the voltage changes curve of each TMR magnetic field sensor are obtained.According to the corresponding relationship between the voltage and the current,the current change curve is deduced inversely and compared with the post-arc current waveform measured by previous studies.In comparison,the two change trends are the same,and the numerical magnitudes are the same,which proves the reliability of the measurement results.The experimental results show that the TMR magnetic field sensor can achieve AC current measurement,the frequency response is timely,and the error is within ±7%.The current value is related to the distance between the TMR magnetic field sensor and the current,The minimum current can measure 90mA.