| Compared with Hydraulic Power Steering(HPS), Electronic Power Steering(EPS) has several advantages: higher efficiency, energy-saving and better performance. EPS gets more and more widely used in cars and small vehicles. There is a trend that EPS will take place HPS in the near future. At present, the assistant motor used in EPS are almost DC Motor. However, DC motor have some intrinsic shortcomings, such as noise, spark, Electro-magnetic interfere and short life because of the existing of electrical brush. Therefore, it is necessary to develop a new brushless servo motor used in EPS. In this thesis, a control system used in a kind of Brushless DC motor(BLDCM) for EPS is studied. The main content is as follows. 1)The structure and working principles of BLDCM are presented. A math model of BLDCM is introduced and the control algorithm is simulated by using MATLAB. The causation of BLDCM torque ripple is analyzed and some methods to decrease torque ripple are presented. 2)A BLDCM controller is designed based on the DSP-TMS320LF2407 and the software flowchart is presented. The reliability and stability of the controller are studied. 3)Performance experiments of BLDCM and EPS are carried out. A large quantity of useful experiment data are achieved. And First-hand data are provided for improving the controller's stability and capability. The experimental results indicate that the BLDCM and controller have such advantages: low cost, good stability and good assistant performance. The BLDCM system is suitable for EPS assistant motor. The research result provides a good developing and testing platform for future's research work.
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