Research On Electronic Current Transformer Based On Distributed Magnetic Field Sensing Technology

Researching on circular hall sensor array at home and abroad are mainly concentrated in two aspects of sensor array structure and signal processing algorithm,research on resist electromagnetic interference and error factor of sensor array is almost blank and valuable to conduct.The research on air-core coil is mainly in the field of air-core coil current transformer,The air-core coil current transformer can only measure current at fixed point due to the wire running through the coil,the research on air-core coil is mainly focused on digital integrals and the study of measuring current with multiple air-core coil is almost blank.Therefore,the current measurement method based on air-core coil sensor array is worth studying deeply.This paper focus on the circular hall sensor array and the current measurement method based on air-core coil:1.Based on the basic principle,this paper makes a detailed study on the resistance of circular hall sensor array to parallel wire current and the off-center,off-angle of primary conductor,the corresponding improvement method is proposed and the simulation results show that the error of parallel wire current interference is less than 0.1% when the number of hall sensors is not less than 8 and the ratio of the conductor spacing to the radius of the circular hall sensor array is more than 2.37,the maximum measurement error is 0.6% when there is off-center of primary conductor and the off-center distance varies from 0 to 5mm,the measurement error is less than 0.1% after improvement and the measurement accuracy can meet the requirement 0.1 class,the maximum measurement error is 0.8% when there is off-angle of primary conductor and off-angle varies from 0° to 10°,so,it is necessary to avoid off-center and off-angle of primary conductor when installing circular hall sensor array.2.On the basis of previous studies of air-core coil,the method of measuring current which is double coil measurement method for single phase current measurement and four-coil measurement method for three phase current measurement using air-core coil sensor array is proposed,and the simulation results show that the measurement accuracy of the double coil measurement method and the four-coil measurement method can meet the requirement of 0.1 class.the research on position bias of air-core coil sensor array has been carried out and the results show that the maximum error of double coil measurement method is close to 2.3%,therefore,it is necessary to avoid position bias when double coil measurement method is carried out;the maximum error of measurement method is 0.66%when there is position bias of four-coil and a correction air-core coil was added in four-coil to improve the measurement accuracy,by comparing the effective voltage values of coil 3and coil 5,the position of four-coil can be corrected.The induced voltage of coil 3 was replaced by the average of the induced voltage of coil 3 and coil 5 to improve the measurement accuracy and the simulation results show that the measurement results meet the accuracy requirement of 0.1 class.