Research On Torque Ripple Reduction Of PMSM Applied For EPS

Electric power steering systems (EPS) has the distinct advantages of energy-saving, efficient, and improve the vehicle steering stability under more and more attention. The steering motor is the main component of electric power steering system. Due to the excellent performances such as high power density, simple drive system and structure, permanent magnet synchronous motor (PMSM) is becoming the mainstream motor used in the electric power steering system. But torque ripple is becoming a major negative factor to limit the application of motor, so the study of permanent magnet synchronous motor control and torque ripple reduction has great significance. This paper mainly study on the control strategy of permanent magnet synchronous motors, torque ripple reduction control methods, the hardware and software system design and implementation of EPS controller.First, introduces the working principle of permanent magnet synchronous motor and the basic content of vector control principle. On the basis of this research and analysis, permanent magnet synchronous motor model based on the rotating coordinate system is established. Then, analyzes the cause of the motor torque ripple and its characteristics, build the mathematic model of the torque ripple.According to the characteristic that the torque ripple is the motor rotor position periodic function, iterative learning control (ILC) method based on the motor rotor position is proposed to reduce torque ripple. The method refer to current control cycle motor torque difference, compensate the next period control signals by the experiences stored in the memory to generate a proper q-axis reference current to reduce torque ripple. Simulation model of the electric power steering systems are built in Matlab/simulink. Compared the torque output changes with ILC and without ILC, verifying the effectiveness of the algorithm the paper proposed.At last, in order to achieve the basic functions of EPS and verify the actual effect of proposed control strategy, the hardware and software system are designed based on the STM32F103 ARM chip. With the existing experimental environment, the experiment carried out to verify the validity of the proposed algorithm and the results show that the algorithm can effectively restrain the torque ripple of permanent magnet synchronous motor in electric power steering system.