Research On Field-Circuit Combined Simulation And Transient Effect Of Magnetic Balance Current Sensor

Magnetic balance current sensor is a kind of current measuring device widely used in rail transit to monitor the running condition of trains.The work mode based on field circuit coupling makes its composition structure include filed parts(such as magnetic core,coil)and circuit parts(such as hall element,circuit board).The overall performance of the magnetic balance current sensor is closely related to the two parts.Therefore,in the early design stage of the sensor,the magnetic parts and circuit parts must be considered comprehensively and simulated jointly,so as to design a practical product meets the requirements of high precision.Based on this,a method of magnetic SPICE modeling based on magnetic scalar potential volume integral equation is proposed in this paper.This method can not only realize the dynamic simulation of the working process,but also simulate the nonlinear distortion and other transient effects of the sensor in actual work,so it can directly serve the actual engineering to guide,optimize and test the design of the product.The main contents include the following parts:Firstly,a precise full-wave electromagnetic simulation model is established for the magnetic parts(coils and magnetic cores),and a field simulation algorithm and software are developed which is based on moment of method of the magnetic scalar potential volume integral equation.These field simulation data will be used as equivalent circuit parameters of magnetic parts to construct the equivalent circuit model.Secondly,on the basis of magnetic field simulation,modeling based on SPICE is studied.The matrix data extracted from the field simulation are directly translated into the circuit model as equivalent circuit parameters of the magnetic circuit,and the field matrix equation of the magnetic circuit is also converted into the Kirchhoff voltage equation of the circuit.This modeling strategy ensures the subsequent circuit simulation still has a full wave accuracy.It is very convenient to use controlled source and other circuit components to construct the corresponding SPICE circuit model.Finally,we can get the combined simulation model of the current sensor,which is unitized in the circuit,so the whole combined simulation can be completed by using SPICE solver.This way of solving the electromagnetic equation in the circuit makes the combination between field and circuit is dynamic,and the transient effect of the signal in the field and circuit can be accurately simulated.Finally,aiming at the defects of time-consuming and poor efficiency,this paper proposes several effective methods to accelerate the simulation,including matrix simplification,matrix sparsity,and magnetic symmetry calculation.These methods simplify the magnetic field equations and matrices,and ultimately condense the magnetic SPICE model.After processed,the field-circuit combined simulation method can be directly used to optimize and guide the early design of the current sensor.