霍尔电流传感器数学模型及其非线性传变分析

Mathematical model of hall current sensor and analysis of its nonlinear transmission

柔性直流系统发生极间故障,电流上升快,持续时间短,给电流传感器正确传变带来了极大的挑战,继电保护必须考虑电流传感器不能正确传变带来的影响。直流系统广泛采用霍尔传感器对电流进行变换,霍尔传感器在极限工况下存在非线性过程。介绍了闭环霍尔电流传感器各部分包括磁电转换部分、电压放大部分、以及反馈补偿电路的工作原理,考虑了铁芯、运算放大器以及三极管存在的非线性特征,建立了带非线性传变环节的数学模型,并在PSCAD数值仿真平台上建立了数值仿真模型。通过数值仿真,分析了闭环霍尔电流传感器各个饱和环节对电流传变的影响及电流发生畸变后的变化特征。

The fast rising current with short duration brings great challenge to the correct transmission of the current sensor when interpolar fault happens in a flexible DC transmission system based on voltage sourced converters.Relay protection must take it into account whether current sensors can transfer primary current correctly.Hall sensors have been widely used to transform the current in the DC system.The nonlinear process may appear when hall sensor works.The mechanism of a closed-loop hall current sensor including the magnetoelectric conversion part,the voltage amplification part and the feedback compensation circuit is introduced in this paper.And considering the nonlinear characteristics of the iron core,operational amplifier and transistor,a mathematical model with nonlinear transmission part is established,then a numerical simulation model is built based on PSCAD.The influence of the saturation section of the closed-loop hall current sensor on the current transmission and the variation characteristics when current distortion happens are analyzed based on the result of this numerical simulation.