Electro-Hydraulic Power Steering System Based On DSP

Electric hydraulic power steering (EHPS) system is a new technique, which is based on traditional hydraulic power steering system(HPS), it introduced BLDCM to control hydraulic pump. Compare with HPS, it has more advantages, such as better steering control, less energy consumption, less time lags and less road impacts.In the project, first of all, the EHPS system structure is analyzed and the math models are established and simplified. Based on the models, the assistant power and turning following character are studied, the method to control BLDCM speed changed with the steering speed and vehicle speed is obtained. According to the method of discrete shortcomings, improved BP neural network is applied to realize the control algorithm at any vehicle speed, and any steering speed. Compare with general BP neural network, improved BP neural network not solve the discrete control blind area and improve the real-time control function, but also reduce the risk of local optimal result, reduce control error.Motor control is significant in the system. In this project, brushless DC motor is applied, in order to obtain good dynamic performance, Direct Torque Control (DTC) algorithm is adopted, meanwhile, control the PWM unit output by comparing the detection values with the given references. Finally, based on the analysis of the BLDCM mathematic model, the working principle, Matlab simulation is established to verify the feasibility, eventually hardware design and software control completed based on the algorithm.The core of EHPS system is the controller, special motor control chip TMS320F2812 is applied to realize the control algorithm, its abundant hardware resource, especially the PWM module and event capture module, facilitate the hardware and software design. With the hardware resources, the motor control module, the power drive module, and the signal processing module are designed, the software design is based on the hardware design.Finally, the EHPS system integrated experimentation platform is established to test the control algorithm, signal processing, motor control performance and the steering control performance. The experimental results verify the feasibility of the EHPS system design, control method is feasible, has achieved the anticipated test requirements.