Research On Modeling And Speed Regulation Of Variable Flux Leakage Permanent Magnet Synchronous Motor

At present,the two major problems of environmental pollution and energy crisis have been recieved widely concerned.As the first new energy vehicle,electric vehicle has gradually become an inevitable trend in the development of automobile industry.For modern electric vehicles,high torque density and wide speed range are two important indexes,which are the key to achieve good dynamic performance of the traction motor.In addition,the interior permanent magnet synchronous motor(IPMSM)with high power density and high efficiency has become the first choice in the field of electric vehicle drive motors.However,due to the constant magnetic field of rare earth permanent magnetic materials,the air gap magnetic field of the IPMSM cannot be adjusted.Then,the speed range of the IPMSM will be limited.Variable flux leakage permanent magnet synchronous(VFL-PMS)motor is a new type of the IPMSM with variable magnetic flux leakage,which has the advantages of wide speed range,high efficiency and high power density.The VFL-PMS motor has potential application in electric vehicle and other fields requiring wide constant power speed regulation.In this paper,a three-phase 36/8 stator/rotor poles VFL-PMS motor is studied.Also,its static and dynamic characteristics,mathematical modeling method and vector control based on open winding are researched.The specific contents are shown as follows:1)The basic structure and working principle of VFL-PMS motor are expounded.Also,the magnetic field distribution,back EMF,flux linkage variation characteristics and inductance characteristics of the motor are analyzed in detail.Based on the equivalent magnetic circuit model,the magnetic circuit variation characteristics of the VFL-PMS motor under multiple operating conditions are studied,and the internal variation mechanism of electromagnetic parameters under various operating modes is revealed.2)The dynamic change mathematical model of electromagnetic parameters of VFL-PMS motor is studied.Considering the loss factor of the motor under operating mode,the mathematical model of the motor with multiple loss variable parameters under different operating conditions is established.Based on Matlab/Simulink,the simulation model of the VFL-PMS motor is constructed.Also,the operation state of the proposed motor model under different torque speed is simulated and compared with that of the general motor model.3)According to the characteristics of VFL-PMS motor,the VFL-PMS motor drive system is established.Based on the current vector control strategy of id=0 in the vector control method,the operation performance of the VFL-PMS motor is studied.Based on dSPACE1007,the experiment is carried out to analyze the operation characteristics of VFL-PMS motor under different operating conditions,which verifies the accuracy of the motor model.4)Based on the open winding structure,several wide-speed control strategies of the VFL-PMS motor drive system are studied.Additionally,and the advantages and disadvantages of each modulation strategy in the voltage output range and zero-sequence voltage are analyzed and verified.Then,a harmonic injection decoupling SPWM modulation strategy is proposed.Based on the decoupling SPWM,the amount of third harmonic injection is also taken as a control quantity.By adjusting the harmonic amplitude,the driving system can have a wide output voltage range and a small zero sequence voltage in the whole output voltage range.Finally,the correctness and effectiveness of the modulation strategy are verified by simulation.