Simulation And Assistance Characteristic Research Of Electric Hydraulic Power Steering System

In the 21 st century, more green, intelligent, safety and comfort have been the subject of automobile development. Steering performance is one of the important indexes of measuring car’s comfort and security, influencing the automobile control stability directly. It has an important role to improve the driving feeling and protect the passenger’s safety. Meanwhile, the development of power steering system also reduces the energy consumption and makes the driver’s steering operation more comfortable. Therefore, the study of automotive power steering system meets the trend of the automobile industry and has great significance to environmental protection.EHPS has good road sense and energy consumption economy which provides a good solution for the power steering of passenger cars and light commercial vehicles. Because PMSM has higher efficiency, better speed regulating and higher power density. It will be the future research hot-spot in the power steering motor and will be the new direction of market. Therefore, the research of EHPS of a pure electric light commercial vehicle based on the control of PMSM has been carried on systematically.Firstly, paper introduces the electric light truck’s EHPS structure, working principle of PMSM drive system. Based on the mathematical model of two phase rotating coordinate system of motor, we put forward the MTPA strategy under the base speed to improve the utilization rate of car batteries and use the weak magnetic technology to make motor speed continue to rise to meet the work requirements of EHPS system when motor reach the base speed.Then, we analyze the basic requirement of EHPS dynamical characteristics and choose the linear dynamical characteristics curve to achieve power control of steering system. Power characteristic curve MAP figure is obtained by MATLAB curve fitting.Designs the engineering parameters of speed and current double closed loop PI regulator in the control system of PMSM, and selects the SVPWM to control IPM module. Using Simulink and S-Function module to build motor control system simulation model. Based on simulation model, we carried on EHPS dynamical characteristics, motor step load input and constant load deceleration simulation analysis respectively.Finally, PMSM test bench was set up by hardware selection and software programming. Based on the test bench, we conduct motor racing, motor load and the EHPS dynamical characteristics test. Results show that the PMSM can accurately reach the target speed fast according to the given speed and steering wheel speed. And EHPS has good following performance which verify the feasibility of the subject on EHPS dynamical characteristics and PMSM control strategy research.