Research On Permanent Magnet Synchronous Motor Model For Electric Machine Emulator

Increasing environmental pollution and the gradual depletion of non-renewable energy are driving the rapid development of the global new energy automobile industry,and new energy vehicles are gradually replacing traditional fuel vehicles.The drive motor and its control system are the key technologies of the new energy vehicle.The development of the electric machine emulator enables the motor controller to complete the test based on the system consisting of the motor controller and the machine emulator,which improves the development efficiency of the motor controller.At present,the permanent magnet synchronous motor(PMSM)emulator mostly adopts a fixed-parameter model as its reference,ignoring the influence of the variable-parameter characteristics of the PMSM on the motor parameters,which reduces the precision of the motor simulation.In this paper,the PMSM model based on variable parameter characteristics in the machine emulator is studied.Based on the operating conditions of PMSM,the magnetic saturation and cross-coupling effects,the harmonic effect of rotor magnetic field,the loss and temperature rise effects and causes of PMSM are analyzed from the causes and their influences on the electromagnetic parameters of the motor.According to the equivalent model of permanent magnet synchronous motor in two-phase rotating coordinate system,the voltage equation,torque equation and motion equation of the motor are derived,and the mathematical model of PMSM is established.Based on the analysis of the variable parameters of the motor,the nonlinear functions of the stator flux and stator resistance with current,rotor position angle and temperature as variables are established.A numerical calculation method is designed to calculate the loss and temperature,and the PMSM calibration bench is established to obtain the above-mentioned nonlinear functions.The functions are substituted for the fixed parameters in the motor model to build the variable-parameter model of the permanent magnet synchronous motor.A motor controller and machine emulator system based on back-to-back inverter modules was built in simulation.The motor model calculation results,the actual outputs of EME and the output results of Simulink's inherent motor module are compared.Firstly,the comparison between the motor model computing results and the outputs of Simulink's inherent motor model shows that the numerical algorithm of the motor model and the solution step size used in this paper are efficient.Secondly,the comparison between the actual output parameters of the machine emulator and the motor model solution results indicates that the closed-loop control system has good tracking results on the motor model computation.Finally,the comparison between the output characteristics of machine emulators based on the constant-parameter model and the variable-parameter model reveals that the variable-parameter characteristics have a significant impact on the motor output characteristics.The experimental platform of motor controller and machine emulator system is designed.Both the motor controller and machine emulator are based on TI TMS320F28335 as the main control chips and IGBT as the power devices.In the experiment,the output characteristics of the machine emulator with constant parameters,the machine emulator with variable parameters and the actual motor are compared under different frequencies and loads,through which the precision of electric machine emulator with the PMSM variable-parameter model established in this paper is verified.Based on two different load conditions of PMSM,the output characteristics of the machine emulator based on constant-parameter model motor,the machine emulator based on variable-parameter model and the actual PMSM are compared.The contrast experiments show that the machine emulator based on the variable-parameter model of PMSM has a good simulation accuracy on the actual motor port characteristics,and the accuracy is higher than the machine emulator based on the fixed parameter model,which makes the constant-parameter motor model more appropriate for electric machine emulator.