Model Analysis And Experimental Reasearch Of EPS Permanent Magnet Synchronous Motor

In recent years,the electric power steering system(EPS)has excellent performance advantages in handling stability,driving comfort and driving safety.EPS is gradually replacing the hydraulic power steering system and becoming the preferred form of power steering.As the actuator of EPS system,the control performance of the motor directly affects the system performance.This subject mainly develops the research work on the control of permanent magnet synchronous motor in EPS system.On the one hand,under different operating conditions,the torque and speed of the booster motor output have a higher followability.On the other hand,the torque ripple of the booster motor should be reduced as much as possible to reach the driver's acceptable range.This paper mainly studies the subject from the aspects of EPS system basic power control strategy,motor FOC control,field weakening control,dead-time compensation,etc.,and mainly completes the following research work:(1)EPS basic assistance control analysis and modelingThe working principle of EPS basic power control is analyzed,determine the power parameters according to the actual needs,and design a curve-type basic power control strategy.Based on the designed curve-based basic power control model,a second-order filter compensator module is established according to the system requirements to improve the stability of the system.(2)Analysis and modeling of FOC control for permanent magnet synchronous motorThe principle of FOC control is studied,the mathematical model of permanent magnet synchronous motor control in different coordinate systems is built,and the PI control model and space vector pulse width modulation model are established.The FOC control model of permanent magnet synchronous motor is established based on Simulink,and the accuracy of the model is verified through simulation.(3)Simulation research on flux-weakening control of permanent magnet synchronous motorThe principle of flux-weakening control of permanent magnet synchronous motors is studied,the change trend of current vector in the flux-weakening process is analyzed,and a flux-weakening control method based on speed and torque is proposed.The flux-weakening control model was built using Simulink and applied to the motor FOC control model for simulation verification.(4)Analysis of dead-time effect and simulation of dead-time compensationThe mechanism of the dead-time effect is studied.In order to compensate for the dead-time of the control model,a Kalman filter is used to filter the current harmonics,reconstruct the three-phase current to determine the sector where the stationary shaft is located,and determine the compensation voltage algorithm.The dead-time compensation model is established based on Simulink and simulation work is performed to verify the effectiveness of the algorithm.(5)Test verification based on motor performance test bench and co-simulationAccording to the test requirements,a permanent magnet synchronous motor performance test bench was built,and the established dead-time compensation algorithm was tested and verified.The Simulink&Carsim joint simulation model is established to simulate and verify different steering operations and analyze the output performance of the motor in the EPS control system.