Study And Design Of Automotive Electric Power Steering Control System

In recent years, electronic technology and motor control technology into the era of rapid development, constantly new technology appears, Electronic Power Steering (EPS) is the trend to replace Hydraulic Power Steering (HPS), and EPS has been the mainstream of the Power steering technology development. This article studies the theory and its working principle of the EPS system, based on the study, designed and developed the hardware circuits and software program, also carried out system simulation performance analysis using Simulink.First, the article describes the structural organization of the electric power steering system, analyzes the operation principles and key technologies. Research about the operation principles of the key Part BLDC and its solutions.Then, introduce the assist control, the return control and the damp control of the three control mode, design the system compensation control. Analyze and compare three kinds of typical characteristic curves, based on this, design a ideal characteristic curve that applies to the EPS. Introduce the principles of fuzzy PID controller, and fuzzy PID controller for the system is designed on the basis of combined experience value.The focus of this paper is to design and develop the hardware circuit of the EPS system. Design uses Freescale’s MC56F8346as the CPU core, and three-phase motor driver chip IR2132as MOSFET driver circuit. On this basis, with the EPS applications and automotive harsh environment characterized designed hardware control platform, including the DSP minimum system circuit (including the clock circuit, the filter circuit, the reset circuit, etc.), the power conversion circuit, the signal processing circuit, the drive circuit, the communication circuit and fault protection circuit, etc. Communication circuit used by the serial communication and CAN bus communication with the communication between the host computer and the vehicle. And hardware reliability is analyzed.Finally, the system’s software program is developed on the design of hardware. The software program is designed by module ideas, including the main program module, the system initialization module, the work mode decision module, the signal acquisition and processing module, the PWM output module, and the Fuzzy PID control module. And the simulink experimental results show that the system effect is good, dynamical characteristics comply with the design requirements.