| With the advantages of high power density,small size and low cost,the integrated application of permanent magnet synchronous motor and reducer has gradually become the mainstream of pure electric vehicle power system application at home and abroad.Due to the characteristics of the system itself,it is affected by electromagnetic field and thermal field of the motor and mechanical dynamic coupling between the motor and reducer,which makes the efficient control of the system considering multi field integrated more difficult.Thus,it is not conducive to the further exploitation of its energy saving potential and the further promotion of pure electric vehicles.In this paper,an integrated electric drive system(IEDS)integrated by interior permanent magnet synchronous motor and reducer is taken as the research object,and the research on the performance characteristics and the corresponding performance optimization control strategy considering the “mechanical-electrical-magnetic-thermal” coupling characteristics of the IEDS is carried out.The main contents of this paper are as follows:(1)The advantages and disadvantages of traditional mathematical modeling principle and finite element modeling method of permanent magnet synchronous motor are analyzed and compared.Based on the finite element model,the law of motor parameters changing with temperature is studied.Then,based on vector control theory,considering the limitation of maximum voltage circle and maximum current circle,SVPWM is used to control the inverter,maximum torque current ratio and flux weakening control strategy are used to control the motor,and a complete motor control system model is constructed.Finally,the " electrical-magnetic-thermal " coupling model of IEDs motor and its control system is built by combining the finite element motor model with the mathematical model of control system.ECE method is used to reduce the order of the finite element motor model,while ensuring the simulation accuracy and speed.And the model is verified by experiments.(2)Based on the method of concentrated parameters,considering the stiffness,damping and meshing error of helical gear pair,the nonlinear dynamic model of gear transmission system is built.Based on the torque output of motor and torque input of gear system,the coupling between motor model and gear transmission system model is realized according to the dynamic formula of torsional vibration between permanent magnet synchronous motor and reducer gear pair.Finally,the "mechanical-electrical" coupling model of IEDS is constructed.(3)Combining the “electrical-magnetic-thermal” coupling model of motor-controller system,and the “mechanical-electrical” coupling model of motor-gear system of IEDS,the “mechanical-electrical-magnetic-thermal” coupling model including motor,controller and gear transmission system is built.Aiming at the dynamic performance of the IEDS in the case of “mechanical-electrical-magnetic-thermal” multi field coupling,the dynamic control efficiency and loss control efficiency of the traditional control strategy under the “mechanical-electrical-magnetic-thermal” coupling are studied,and the influence of harmonic current on the output dynamic performance of the IEDS in the case of “mechanical-electrical-magnetic-thermal” coupling is studied.(4)Taking the “mechanical-electrical-magnetic-thermal” coupling model of the IEDS as the research object,aiming at the problem that the traditional control strategy can not control the IEDS to achieve the maximum energy saving potential under the condition of variable temperature,and the torque fluctuation problem under the condition of current distortion,an energy consumption optimization and torque ripple suppression control strategy considering “ mechanical-electrical-magnetic-thermal”coupling based on “torque-speed-temperature” query table is proposed.Finally,field circuit coupling simulation and finite element simulation are used to verify the effectiveness of the proposed control strategy.The effectiveness of the proposed control strategy is verified by field circuit coupling simulation and finite element simulation.Finally,the effectiveness of the proposed model and control strategy is verified by experiments. |
