Research On Model Predictive Control Based On Direct Torque For Permanent Magnet Synchronous In-wheel Motor Of Electric Vehicles

In order to solve the energy crisis and environmental pollution and other global environ mental issues,research and development of zero pollution,zero-emission new energy electric vehicles is imminent.At present,there are three major technical difficulties in the development of electric vehicles.Among them,the motor drive system is a direct execution part of the vehicle control,so its control effect will directly affect the stability and safety of vehicle.The permanent magnet synchronous in-wheel motor drive system due to the outstanding advantages in terms of energy conversion efficiency,lightweight vehicle,vehicle comfort and handling stability,is currently the most promising motor drive system.The core problem of electric vehicle drive system control is the control of the motor.The classical control methods of permanent magnet synchronous motors are field-oriented control and direct torque control.Compared with the field-oriented control,the direct torque control method avoids repeated coordinate transformation,simplifies the system structure and improves the response speed,so this paper chooses direct torque control for research.Facing the problem of large torque ripple in traditional direct torque control,this paper first proposes a feedback linearization control scheme based on direct torque control for permanent magnet synchronous motor.Through the design of the feedback linearization controller and the role of the SVPWM module,the accuracy of the motor torque tracking control is improved.However,its control accuracy is still difficult to meet the control requirements of electric vehicles on drive system.Moreover,in addition to considering the tracking control accuracy,the energy consumption of the motor drive system will reduce the utilization rate of the electric vehicle battery energy and shorten the cruising range.The motor drive system serves as the power heart of the vehicle,and the safety of the system directly affects the safety of the vehicle control.Therefore,while ensuring accurate torque tracking,the energy consumption and safety issues of the drive system still need to be considered.In addition,the application of the SVPWM module makes the system structure more complex,aff-ects the response speed of the system,and conceals the advantages of DTC.In order to solve the above problems,this paper proposes a finite-set direct torque model predictive control algorithm.This method uses the design of state quantity tracking,energy consumption,and limit cost functions in the objective function to solve the problem of the single control target,and achieves direct control of the three-phase inverter through the solution of the optimal switch combination.This method improves the control accuracy while simplifying the control system,increasing the response speed,and completing the optimization control of the permanent magnet synchronous motor to a certain extent.However,in the implementation of the finite-set direct torque model predictive control algorithm,the effective voltage vector that is solved will affect the entire control cycle,which will cause additional errors and increase the working intensity and energy loss of the inverter,and the switching frequency is not fixed.In order to solve the above problems and strengthen the control of inverter,apply the duty cycle modulation method to improve the finite-set model predictive control algorithm,and propose a direct torque model predictive control algorithm based on the duty cycle modulation for the permanent magnet synchronous motor.Through duty cycle modulation,the action time of the effective voltage vector is accurately controlled,which further improves the accuracy,reduce inverter working time,extend service life and reduce energy loss.Finally,the motor control algorithm proposed in this paper is verified in Matlab-Simulink environment.The main content and innovation:1.Aiming at the problems of insufficient control precision and single control target in traditional direct torque control and direct torque feedback linearized control algorithm,the finite-set direct torque model predictive control algorithm was proposed.This method considers torque and flux tracking control,energy consumption and safety of the drive system at the same time,improve control accuracy,simplify the system,increase response speed,and improve the overall performance of the motor drive con-trol system.2.In order to further strengthen the control of the inverter and improve the control accuracy of the system,a direct torque model predictive control algorithm based on duty cycle is proposed.The duty cycle modulation method is used to precisely control the action time of the optimal switch combination in the three-phase inverter,improve the control accuracy of the drive system,optimize power device working time and ex-tend service life.