Magnetic Control Of Permanent Magnet Memory Motor Based On Cuk Converter

Permanent magnet motors have the advantages of high power density and large output torque,so they have been widely used in electric vehicles,household appliances,aerospace and other fields.Most permanent magnet synchronous motors solve the problem of bus voltage limitation through field weakening control.However,additional losses will be generated in the field weakening control,which reduces the operating efficiency of the permanent magnet synchronous motor.With the rapid development of electric vehicles,a new type of permanent magnet memory motor(PM-MM)has been proposed and applied to electric vehicles.Because the motor has the characteristics of adjustable air gap flux density,it adds a degree of freedom compared with the permanent magnet synchronous motor control system.PM-MM mostly uses a mixture of low-coercive force permanent magnets and high-coercive force permanent magnets as the rotor topology of the motor.When the motor is charged and demagnetized,a continuous pulse current is injected into the d-axis to change the low-coercive force permanent magnets of the magnetization to achieve the control of the motor flux.Because PM-MM solves the problem of motor loss caused by the continuous field weakening current in permanent magnet motor field weakening control,the operating efficiency of the motor is significantly improved.Therefore,the motor has broad application prospects in electric vehicles and other fields.Compared with traditional permanent magnet synchronous motors,PM-MM has one more degree of freedom,so the PM-MM control system is more complicated.Many problems in the process of charging and demagnetizing of this motor are worthy of in-depth study,and the problem of bus voltage limitation in the process of charging and demagnetizing is especially protruding.By analyzing two different control strategies in the operation of PM-MM,this dissertation reveals that the bus voltage in the process of charging and demagnetizing has limitations on the motor operating efficiency,and a Cuk converter based on the traditional control strategy Improved control strategy of permanent magnet memory motor.In the magnetization process,when the input voltage of the inverter side cannot meet the voltage requirements of the memory motor,the improved control method proposed is to change the output mode of the Cuk converter proposed in this paper to compensate the memory motor during the process of magnetization and demagnetization.The improved control method proposed in this thesis effectively improves the speed and accuracy of magnetization and demagnetization of permanent magnet memory motors,and improves the operating efficiency of memory motors.Finally,a permanent magnet memory motor experimental hardware control platform is built,and the designed topology and control method are applied to the permanent magnet memory motor control system.Analyzing the experimental results of the converter proposed this thesis in the conventional operation mode and charging and demagnetizing mode of the memory motor,the correctness and practicality of the of the permanent magnet memory motor control method proposed are verified.