Development Of Controller Of The Electric Power Steering System Based On DSP F2812

Electric Power Steering System (EPS) is a dynamic steering control system which can real time supply assist torque according to the status of the automobile movements and driver's requirements. Automobile equipped with EPS can meet the requirements of the higher maneuverability for low speed driving and the stability for high speed driving. Electric Power Steering Systems offer improvements over conventional mechanical steering systems or hydraulic assist systems by improving fault-tolerant, disturbance rejection, fuel economy, start-up on low temperature, safety and environmental friendliness, which makes the EPS the main steam of future power steering systems and an intense target of current technology innovation.An EPS system controller based on DSP is thus developed in this thesis to meet the industry demands. It uses TMS320F2812, an advanced and powerful 32-bit fixed point model of TMS320C28x series, as its ECU.At first this text has described electronic power steering system of structure type, operation principle, constitution and performance characteristic of key position of system, which have offered the basis for systematic development and selection of the part. And the development history of EPS was introduced. The control strategy of EPS was studied and certain control strategy was adapted after theory of EPS was analyzed deeply. PID control used in EPS control strategy was studied in details.Then the EPS system dynamics model and the computer simulation model has been established, and simulation analysis by SIMULINK has been carried on the systems control performance. It is seen that selected by the control method and the control strategy have the very good control effect through the simulation analysis, which can be used as the control logic of the EPS system controller.Then the function of the EPS system ECU is multi-analysis, and the research on ECU has be developed take DSP TMS320F2812 as microprocessor. The control unit has real-time data signal gathering and the system's control function, according to data signal which gathers, the definite goal current of motor is outputted, and the PWM pulse-duration modulation technology is used, through the H bridge circuit control motor output current and the rotation direction, and the function of EPS system is realized.After the hardware circuit design has been carried on, the corresponding software procedure has been established. The software procedure has used based on the severance modular design method, realized the data acquisition, the motor numeral PID closed-loop control and the torque-control of the motor, as well as the breakdown reports and so on the function.At last, the present thesis introduced the innovative bed test device, by which the bed test on circuit and software system was performed, as well as analyzed and demonstrated the test result. The result showed that the electronic control unit designed was with stable performance, appropriate structure and excellent matching condition, and the excellent power steering effect could be ensured by EPS.