Research On EPS System Control Strategy Of Pure Electric Vehicle

The steering system is an important part of the automobile chassis,which controls the vehicle to maintain or changes the direction of forward.Steering system is constantly upgrading,and it has experienced several stages,such as purely mechanical steering,hydraulic power steering,electric hydraulic steering,electric power steering and so on.At present,the application of hydraulic power steering occupies the main part,and it's technology is more mature,however,it also has itself inherent problems such as leakage and pollution.The propose of electric power steering causes a new craze about the power steering study,and electric power steering system,with its simple structure,less components,low energy consumption,no pollution,easy to control,and many other advantages get the favour of domestic and foreign well-known car manufacturers.The source of the subject is from the company and school which based on a “city logistics car is converted into a pure electric vehicle(CX2014-45)” project,the pure electric vehicle electric power steering system was researched and designed.(1)Several existing steering structures in present were compared and analysed to indicate the advantages of electric power steering system.(2)Several existing control strategies of electric power steering system were comparaed.The electric power steering system dynamics model was established,which was based on the modified the parameters of pure electric vehicles and control requirements,then the control strategy of electric power steering system was studied and designed.(3)The electric power steering systems of the PID control and fuzzy PID control were built by Matlab/Simulink.And the dynamical characteristics of the design and control strategy were simulated and analysed by using these models.It proves that dynamical characteristics of the design can pay attention to both steering portability of the steering system and road sense,and it also proves that the fuzzy PID control strategy can effectively improve the power stability and anti-jamming ability of the steering system.(4)The hardware and software of EPS control system are designed.The STM32F103 is chosen as the master chip of the EPS system,and the EPS system hardware circuit were designed,such as the minimum system circuit,the signal processing circuit,the sampling circuit,the communication interface circuit,the driving circuit and so on.