Study And Design Of Large DC Current Sensor Based On Hall Effect

In the power supply control system of the J-TEXT nuclear fusion device,the large DC current sensor,which plays the role of current mearsurement,is one of the key components.Due to the complex electromagnetic environment of the J-TEXT device and the complex line layout of the power supply system,large DC current sensor with high precision,small volume and light weight has become an urgent demand.In this paper,three types of current sensors based on Hall Effect has been studied,including sensor arrays,open loop and closed loop.A 10 kA current sensor based on closed loop has been designed.According to the design of the magnetic core and related elements,the volume and weight of the closed loop Hall current sensor are reduced to a certain extent.Firstly,the measurement methods of large DC current are introduced briefly,and the characteristics of various kinds of large DC sensors are compared and analyzed.The basic principle of three kinds of sensors based on Hall Effect,including ensorarray,open loop and closed loop has been introduced.The influence of theexternal interference is analyzed in detail and closed loop is chose as the method of current measurement.A 10 kA DC current sensor based on closed loop is designed.With the help of finite element modeling and simulation,the influence of the iron core cross section and the length of the air gap on the magnetic field distribution of the Hall element is analyzed.The unbalance of feedback current caused by the side conduct is analyzed.And the design parameters such as the turns and the diameter of the feedback coil is discussed.The high power amplifier LM3886 is used for the design of power amplifier circuit.The large power BWL resistor with high precision is used as sampling resistance to realize the current measurement.In the guidance of theory analysis,a 10 kA Hall current sensor based on closed loop is developed.A 10 kA equal ampere-turns test platform is developed which is used for the test of the designed sensor.Test results show that the accuracy reached to 0.73%.The researchdone in this paper can provide reference for the design of DC current sensor with large range,small size and light weight.