Research On High Precision Current Sensing Technology Based On Multi-Sensor Data Fusion

Modern power grids have higher and higher requirements for the accuracy of current measurement.Only one current sensor can not meet the requirements of current measurement.Multi-sensor data fusion technology can greatly improve the effectiveness and usefulness of the measurement system.This paper takes the Hall sensor(Hall)and the giant magnetoresistive sensor(GMR)as the object,and conducts research on multi-sensor fusion technology.At the same time,the advantages of the two sensors are brought into play,their respective limitations are reduced,and the accuracy of current measurement in power systems is improved.First of all,based on the analysis of the basic principles and characteristics of Hall and GMR,a method to reduce the temperature drift of Hall is proposed,which is a symmetrical Hall current sensor.Under constant voltage drive,the sensitivity difference caused by Hall’s unbalanced voltage is the principle.Related circuits are designed,including power supply circuit and arithmetic circuit,which effectively reduces the temperature drift of Hall,and provides a basis for improving the performance of the combined closed-loop current sensor.Second,a multi-sensor fusion scheme based on Hall and GMR is proposed.The fusion domain composed of the measured current i and the sensitivity difference AS is divided into four domains.In domain Ⅱ,the multi-sensor weighted observation fusion Kalman filter algorithm is used;in domain Ⅰ,the method of data weighted fusion optimal weight distribution is used;In domain Ⅲ,the distribution of weights is opposite,and a smooth transition of data fusion can be realized between domains.Thirdly,based on the multi-sensor fusion scheme,a multi-sensor fusion implementation method based on Hall and GMR—combined closed-loop current sensor is designed.The combined current sensor consists of two Hall elements and a giant magnetoresistive element placed side by side and overlapped,and is composed of a multi-sensor data fusion module,a circuit module and other parts.The design of combined closed-loop current sensor includes magnetic core,related amplifier circuit,signal acquisition circuit,and feedback circuit design,and the validity of the circuit is verified by simulation.Finally,a Hall and GMR component characteristic measurement platform was built,and the temperature characteristics and measurement current ranges of a single Hall,a single GMR,and a symmetrical Hall current sensor were compared,and the symmetrical Hall current sensor was verified to have the effect of reducing temperature drift.The multi-sensor fusion algorithm experimental platform of the combined closed-loop current sensor has verified that the accuracy of the combined closed-loop current sensor after applying the multi-sensor fusion algorithm is much higher than that of a single Hall or single GMR,and is stable in the range of tens of amperes to hundreds of amperes.The performance is good and meets the expected requirements.