Research On Current Predictive Control For Vehicle Permanent Magnet Synchronous Motor Drive System

With the development of clean energy vehicles industry in recent years,electric vehicles not only solve the problem in energy shortage,environment pollution,but also improve the vehicle’s driving performance.The working conditions of the permanent magnet synchronous motor(PMSM)’s driving system are complex and changeable.The control characteristics of PMSM are multivariable,strong coupling and nonlinear.Commonly used double current closed-loop regulation and traditional current predictive control are hard to achieve fast response of reference instruction without overshoot in full speed range.This paper focuses on the improvement of the current predictive control strategy of the vehicle used PMSM driving system.This paper firstly establish the mathematical model of PMSM driving system,which considering the nonlinear variation of d and q axis inductance.According to the MTPAcurve and voltage ellipse restriction curve,combined with the electromagnetic simulation data,we get the corresponding relation table between the reference torque and the reference current at different speeds,and build the basic driving system simulation platform.With the discrete motor model,the control timing logic of the DSP chip is analyzed.The inherent delay period in the control process is pointed out.On this basis,to meet the needs of vehicle electric drive system,the traditional current prediction algorithm is improved to guarantee the large torque output during high speed operation.The simulation results show that the advanced current prediction algorithm can maintain good torque dynamic response performance and small steady-state error during the wide speed range.Due to the limited voltage provided by the power batteries of the electric vehicle.In order to achieve fast response under voltage limitation,the current trajectory control is added to improve the performance of the system based on the advanced current prediction control.The single period current moving area in the current plane is calculated according to the operating characteristics of the inverter,and three different control trajectories are designed according to the different performance aims.The simulation results show that all three different trajectory control strategies make the inverter fully used the voltage provided by batteries and achieve their own performance aim.Considering the difference between the simulation model and the test model as well as the model algorithm and the code implementation,the test machine is tested by the dynamometer bench.The experimental results show that the advanced current prediction algorithm with current trajectory control can significantly improve the torque response speed under the condition of voltage limitation,but has a high dependence on the motor model parameters.This paper is aimed at the problem that the traditional control strategy of PMSM is not good at torque response during high speed operation.An advanced current predictive control strategy is proposed.Under the condition of voltage restriction,this method can improve the torque response speed significantly and maintain good stability at high speed.Thus,the acceleration performance of the electric vehicle and the safety and stability of high speed driving are effectively improved.