The Design Of EPS Controller Based On Permanent Magnet Synchronous Motor

With the progress of automotive-related technology, automobile power steering system has gone through several stages of development, including hydraulic power steering system, electric hydraulic power steering system and electric power steering system. Electric power steering system with the advantages of compact structure, low energy consumption and easy assembly has become a future development direction of automobile power steering system. The EPS controller based on permanent magnet synchronous motor is designed in this paper.Firstly, coordinate transformation in FOC is introduced in detail. The basic idea and implementation of SVPWM are discussed. The bottom control system of PMSM is built based on FOC and SVPWM.Secondly, a parametric steering characteristic curve is proposed. An appropriate trigger rule for return control and a kind of return control strategy based on PID are made. The whole vehicle model, control system model, driver model and road model are established with Carsim and Simulink. Co-simulation results verify the effectiveness of the assist control strategy and the return control strategy.Thirdly, STM32F103ZET6is chosen as the core chip of EPS controller. Power circuit, core chip minimum system circuit, sensor signal acquisition circuit, motor drive circuit, CAN communication circuit and fault indicator circuit are designed. The problem of high current withstanding and MOSFET heat dissipation are also solved.Fourthly, the EPS controller software is designed in RealView MDK by using ST’s firmware library and motor control software library. The EPS controller software includes system initialization program, motor rotor position determination program, steering wheel angle signal processing program, position type PID control program, AD conversion program and PMSM control program, etc.Finally, the real vehicle test of EPS prototype is implemented in accordance with the relevant national standards to verify the effectiveness of the EPS controller. The real vehicle test results show that the EPS controller can improve the steering portability and the return-to-center performance of the test vehicle.