The Design Of Electric Power Steering System Of Pure Electric Vehicle

With the development of microelectronics technology and control theory, the applicable scope of the electric power steering system (EPS) is more and more wide. As a direction for the future development of the auto industry, adaptation of pure electric vehicle with EPS system has become a research focus which also has practical significance. In this paper, we chose column type electric power steering system of pure electric vehicle as the object of study, did a series of thorough study combined with the theoretical research, system modeling and simulation and bench test of the EPS system. The main research contents and the work are as follows:1) The characteristics of electric power steering system, the working principle have been studied in detail, followed by the mathematical modeling of mechanical steering system and the DC motor.2) A new characteristic curve is designed by the method of fuzzy control theory according to the characteristics of pure electric vehicles and the drivers’ requirements. At the same time, by the simulation on the Matlab/Simulink platform, it was proved that the designed characteristics curve has reached the control target and has good assist characteristics.3) A current tracking controller was designed based on the principle of SMVS. Then, we confirmed the relevant control parameters by simulation. The simulation also proved that the design of the controller had good tracking ability on the reference current.4) The hardware and software of the EPS system controller are designed. The controller hardware circuit board which included the main control chip and the signal processing circuit, the power switching and motor drive circuit has been analyzed and designed. Specific chart flow of the software program is designed according to the EPS system’s work process.5) On the basis of the original car accessories, the bench test of the EPS system was designed and established. Determined the function, the composition, input signal simulation and sampling scheme of the EPS system test bench.