Flux Weakening Performance And Control Analysis Of A Novel Dual-Stator Hybrid Excitation Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)has small size,light weight,simple structure,high torque density and high efficiency.It is widely used in various fields of national economy such as household appliances,office equipment,precision machine tools,aerospace,precision electronic equipment,industrial automation,electric vehicles,etc.However,the permanent magnet magnetomotive force of the PMSM is fixed,the permanent magnet flux cannot be adjusted,the speed regulation range of the PMSM is not wide enough,so the constant power operating range of PMSM is relatively small.When the speed is above the base speed,PMSM needs to perform flux weakening speed control,that is,increase the d-axis current to generate the demagnetizing magnetic field.The d-axis current will increase the capacity of the inverter and may cause permanent magnets demagnetization.The shortcomings of PMSM limit its wide applications.This paper studies a novel double stator hybrid excitation permanent magnet synchronous motor(HEPMSM),which can solve the above problems.This paper analyzes the background of the hybrid excitation idea which overcomes the shortcomings of PMSM,and studies the development status of hybrid excitation motor.The classification of hybrid excitation motor is illustrated.The operation principle and characteristics of hybrid excitation motor are described.In this paper,a novel double stator HEPMSM is proposed.The structure model and parameters of the motor are introduced.The structure and principle of magnetic circuit is introduced.The motor is simulated by 3D finite element software.The performance of back electromotive force,air gap magnetic density,inductance and cogging torque are analyzed,which fully demonstrates the performance characteristics of the presented motor.In this paper,the torque of the motor is modeled by a mathematical formula,and the motor's mathematical model is analyzed by combining the specific parameters such as flux and inductance of the motor.This paper focuses on three typical working modes of the motor,and compares the output torque,air gap magnetic field,winding back EMF and motor magnetic density in various working modes.In the typical working mode of the motor,the output torque is the largest when the radial and axis stator apply q-axis current.In the weak magnetic mode,the output torque of the motor is larger when the q-axis current is applied to the radial stator and the d-axis demagnetizing current is applied to the axial stator.In this paper,the different control methods of PMSM are introduced,and the flux weakening principle of PMSM is analyzed.The equivalent model of the motor is built by Matlab simulink software.The equivalent model is used to analyze the torque and speed of the motor under three different working modes.The double closed-loop control strategy of the motor is discussed in this paper.The radial stator can be used as the main driving unit.The radial windings can be controlled by double closed-loop control with a d-axis current of 0.The speed and torque of the motor can be controlled.The axial stator is used as the auxiliary unit.Only the current closed-loop control is used.The d-axis current is applied to adjust the air gap flux or the q-axis current is applied to output the assistant torque.This chapter studies the torque and speed under the control strategy,and shows the working characteristics of the motor.In this paper,a prototype experiment was carried out on the proposed motor to verify the performance of the motor.The control program,hardware circuit and experimental platform of the motor experiment were demonstrated.Different algorithms were applied to the motor control.The dynamic performance of the motor including the no-load back EMF,the flux weakening back EMF and the load torque of the motor were tested.Moment,verifying the performance and advantages of the motor.