Research On Electromagnetic Design And High-precision Simulation Modelling Of Permanent Magnet Synchronous Motor For EV Applications

Permanent magnet synchronous motor(PMSM)has become one highly competitive candidate for industrial applications such as household appliances,aerospace industry,rail transit,and electric vehicles(EV)due to the advantages of high efficiency,high power density,good robustness and wide speed range.In this paper,the electromagnetic design and optimal control of PMSM for EV applications are studied.The high-precision simulation modelling method of PMSM and the optimized flux weakening control for higher motor efficiency and lower torque ripple are researched systematically.The main work is as follows:First of all,the common methods of electromagnetic design of PMSM are discussed.The main dimensions of a 15 kW PMSM for EV application are designed and analysed.To work out optimized designing scheme of the PMSM,the finite-element-method is applied for structure and dimensions optimization,PM material choosing,and the enhancement of the loss of magnetic characteristics.Secondly,the principles of mathematical modelling of PMSM are expounded.The influence of saturation and cross-coupling effect on the PM flux linkage and stator inductance under different operating conditions are analysed.Then,high-precision simulation model is built,with which high-precision simulations of PMSM are achieved.In addition,several common control strategies of PMSM are discussed.The maximum torque per ampere(MTPA)control and flux weakening control are applied to carry out simulations for the transient-state and steady-state characteristics of the 15 kW PMSM.Thirdly,according to the characteristics of EV driving,motor efficiency and torque ripple are selected as the optimization target of flux weakening control,with which the optimization function efficiency-to-torque-ripple ratio(ETRR)is proposed.Then a simulation designing scheme for ETRR optimization in the entire operation range is constructed,with which the research of optimal ETRR control achieving of PMSM is conducted.Finally,based on the designed 15 kW PMSM,simulations and experiments are carried out to validate the accuracy of the high-precision PMSM simulation model and the effectiveness of the optimal ETRR control strategy.