Research Of The Light-Medium Size Commercial Vehicles Electric Power Steering System

Electronic Power Steering (EPS) system is the trend to replace Hydraulic Power Steering (HPS) system,because it has not only the advantage of smaller volume, lighter weight, simpler structure, easier installation and maintenance, lower consumption, better environmental protection, but also can improve the dynamic and static performance of the automobile, improve the drivers'coziness and security, so fits for many kinds of vehicles such as cars, commercial vehicles etc. At present, light medium size commercial vehicles electric power steering system has not relevant research. Therefore, studying and developing this kind of electric power steering system is a great significance to improve our country's technological level of auto industry.This dissertation aims to study the key technology of light medium size commercial vehicles electric power steering system, to make a systematic and theoretical basis for the design and development of EPS system. This dissertation makes some advances on these following aspects:Two power transmissions coupling are built which are applicable to light medium size commercial vehicles EPS system. By the dynamics and kinematics analysis of these programmers, as well as by the impact of the performance analysis and comparison, the power transmission coupling applicable to light medium size commercial vehicles EPS system is selected. These have made a theoretical basis for the system design.By the transmission coupling of light medium size commercial vehicles EPS system, the contracture of the EPS system is designed, the special hardware of it are selected and analyzed. A kinetic model of light medium size commercial vehicles EPS system is built and further transformed to a state-space model which is more fitted to control. Comprehensive evaluation of EPS system and automotive system to manipulate performance indicators are put forward and these expressions are deduced. By computer simulation study of the variable parameters on the performance indicators to the impact of the steering system, a theoretical basis for the selection and optimization of parameters and the optimization of EPS system development are ready.By the analysis of the power of the commercial vehicles curve characteristics, the specific design requirements and methodologies of light medium size commercial vehicles power steering characteristic curve and criteria are designed. A specific design example is taken. A theoretical basis is made for the practical application.The EPS system control strategy has been analyzed, especially the permanent magnet brushless DC motor-related has been mainly researched. And then, the DC-detection technology and weak magnetic principle are researched, and the EPS system of motor control is simulated. These provide a theoretical basis for the development of EPS system control.