Research On Efficiency Optimization Control Of Permanent Magnet Synchronous Motor For Vehicle

Permanent magnet synchronous motors(PMSMs)have the advantages of simple structure,reliable operation,light weight and high efficiency,and have been widely used in electric vehicles and other fields.Since the vehicle motor drive system uses battery power supply,it also works under complex and variable speed and load conditions,therefore,in addition to satisfying the dynamic control performance of the control system,the efficiency of the controlled motor operation has also been put forward higher requirements.The Interior permanent magnet synchronous motor(IPMSM)is regarded as the object of this paper,and the efficiency optimization control strategy suitable for a wide speed range is studied.The following contents are mainly included in this paper:(1)First,the development background of the electric vehicles and the permanent magnet synchronous motor drive system for vehicles is briefly introduced,and the advantages and disadvantages of the Field-Oriented Control(FOC)and Direct Torque Control(DTC)of the permanent magnet synchronous motor and the development of related control technologies are introduced,and some current control methods for efficiency optimization of PMSMs and their research status are given.Then the theory of Clarke and Park coordinate transformation is introduced and the mathematical model of IPMSM is established in the three-phase static coordinate system A-B-C and the two-phase rotating coordinate system d-q respectively.The control principle of three-phase voltage source inverter and the principle of space vector pulse width modulation(SVPWM)are briefly described.Finally,the basic principle of the maximum torque per ampere(MTPA)control is introduced,a simulation model is built in combination with the FOC theory,and compared with the traditional i_d=0 control.(2)The flux weakening control(FW)method of Interior permanent magnet synchronous motor is studied.The principle of field weakening control and the field weakening capabilities of different motors are analyzed,and the stator current trajectory in different areas is discussed in detail.The current calculation formula for constant power flux weakening and maximum torque per voltage(MTPV)control is given.Finally,a simulation model of field weakening control is established to realize the control in a wide speed range.(3)Then the loss during the operation of the permanent magnet synchronous motor is introduced,the loss model of IPMSMs is established,the conditions for minimizing the loss are deduced,and a numerical method is proposed to solve the conditions for minimizing the loss.Under the limitation of current limit and voltage limit,the application of loss model method is extended to above the rated speed.A motor simulation model including iron loss is built,and the algorithm is simulated and verified.Compared with the traditional field weakening control,the calculation process of the minimum loss strategy is unified,and there is no need for strategy switching in different speed ranges,and the simulation results show that this method can optimize the motor loss in the full speed range and make the motor more efficient.(4)Finally,considering the dynamic conditions,the loss minimization conditions are re-derived,and an efficiency optimization control method based on the dynamic model is proposed.According to the characteristics of the loss model method that depends on model parameters,the iron loss branch current is observed based on the extended Kalman filter,the equivalent iron loss resistance is calculated in real time,and the loss model is updated.There is no need for complex parameter tuning of the iron loss resistance,and the loss model can be corrected in real time to improve the accuracy of the model.Finally,the effectiveness of the strategy proposed in this paper is verified by simulation,and the dynamic response,efficiency optimization ability and reluctance torque utilization are respectively analyzed.The loss minimization under dynamic conditions can be calculated by the proposed method,so the system efficiency can be optimized regardless of dynamic or steady state.Meanwhile,the ability to quickly respond to changes in speed and torque can be maintained within the full speed range,so that the high-efficiency and rapid requirements of the electric drive system can be met.