Study Of Permanent Magnet Coreless Brushless DC Motor Control System Used In Electric Power Steering System

Electric power steering (EPS) is surely the direction of the development of steering system in modern vehicles. It has been being a high-and-new technique product among modern vehicle's components. The DC motor, which is mostly used in present EPS system, is becoming more and more inefficient in matching the fast development of electronic technique in modern vehicles. The appearance of brushless DC motor (BLDCM) brought the development of EPS a new opportunity. BLDCM does not only possess almost all the advantages of a DC motor, but also has a series unique advantage. The way of taking the place of DC motor by a permanent magnet coreless brushless DC motor (PMCBDCM) gives a totally new method for the development of EPS in the future.This paper firstly gives a brief analysis on the structure and working theory of PMCBDCM. Mathematical model of PMCBDCM is built, and its control method for regulating speed is discussed. The causes of torque ripple and the ways of reducing it are analyzed as emphases. Based on the design methods of BLDCM control system, the principle and method of PID regulator are introduced, and a current control strategy is put forward in order to accord to the requires of BLDCM control system in EPS. Its simulation model is built and the analysis of simulation results is given.The control system of PMCBDCM is developed, in which the TMS320LF2407 is used as the MCU and the IR2130 as the pre-drive circuit. The modularization software design is also compiled. Some safe measures of improving the reliability and some software anti-jamming techniques are raised. Based on the all above work, the generator experiment, no-load experiment and load experiment have been done. Some waveforms and data are recorded. And some data are operated in a graphic way. At last, the experiment results are analyzed.The experiment results indicate that the PMCBDCM control system developed is viable, and the EPS system matched with PMCBDCM as assistant motor has good mechanism performance, high efficiency and strong reliability. And this result could give a use for reference to the future development of EPS system.