Su Huafeng, Li Haojun, Liang Weihao, Shen Chaolan, Xu Zheng
Dongguan Power Supply Bureau of Guangdong Power Grid Co., Ltd., Dongguan 523120, China.
School of Electrical Engineering, Chongqing University, Chongqing 400044, China.
Sensors (Basel). 2024 Jan 9;24(2):388. doi: 10.3390/s24020388.
This paper proposes a non-contact current measurement method for three-phase rectangular busbars based on TMR (tunneling magneto-resistance) sensors, due to their advantages of large dynamic range, wide bandwidth, light weight, and easy installation. A non-contact current sensor composed of only three TMR sensors is developed and the TMR sensors are respectively placed at a location with a certain distance from the surface of each rectangular busbar to measure the magnetic fields generated by the busbar currents. To calibrate the developed current sensor, i.e., to establish the relationship between the magnetic fields measured by the TMR sensors and the currents flowing in the three-phase rectangular busbars, we designed a thyristor-controlled resistive load as a calibrator, which is connected to a downstream branch of the distribution cabinet. By switching the resistive load, a calibration current, which can be identified from the background current, is generated in one rectangular busbar and its value is measured at the location of the calibrator, and transmitted wirelessly to the location of the TMR sensors. A new and robust method is proposed to extract the voltage components, corresponding to the calibration current, from the voltage waveforms of the TMR sensors. By calculating the proportional coefficients between the calibration currents and the extracted voltage components, online calibration of the current sensor is achieved. We designed and implemented a current measurement system consisting of a current sensor using TMR sensors, a thyristor-controlled resistive load for current sensor calibration, and a data acquisition circuit based on a multi-channel analog-to-digital converter (ADC). Current measurement experiments were performed in a practical distribution cabinet installed in our laboratory. Compared to the measurement results using a commercial current probe with an accuracy of 1%, the relative error of the measured currents in RMS is less than 2.5% and the phase error is less than 1°, while the nonlinearity error of the current sensor is better than 0.8%.
本文基于隧穿磁阻（TMR）传感器提出了一种用于三相矩形母线的非接触式电流测量方法，这是由于TMR传感器具有动态范围大、带宽宽、重量轻和易于安装等优点。开发了一种仅由三个TMR传感器组成的非接触式电流传感器，并将TMR传感器分别放置在距每个矩形母线表面一定距离的位置，以测量母线电流产生的磁场。为了校准所开发的电流传感器，即建立TMR传感器测量的磁场与三相矩形母线中流动的电流之间的关系，我们设计了一个晶闸管控制的电阻负载作为校准器，它连接到配电柜的下游支路。通过切换电阻负载，在一个矩形母线中产生一个可从背景电流中识别的校准电流，并在校准器位置测量其值，然后无线传输到TMR传感器的位置。提出了一种新的鲁棒方法，从TMR传感器的电压波形中提取与校准电流对应的电压分量。通过计算校准电流与提取的电压分量之间的比例系数，实现了电流传感器的在线校准。我们设计并实现了一个电流测量系统，该系统由一个使用TMR传感器的电流传感器、一个用于电流传感器校准的晶闸管控制电阻负载以及一个基于多通道模数转换器（ADC）的数据采集电路组成。在我们实验室安装的实际配电柜中进行了电流测量实验。与使用精度为1%的商用电流探头的测量结果相比，测量电流的均方根相对误差小于2.5%，相位误差小于1°，而电流传感器的非线性误差优于0.8%。
