Design Of BLDC Motor Control System Based On ST7MC

With the development of high performance thulium PM materials, microelectronics technology, modern intelligent control technology and power electronics technology, especially high-power semiconductor devices, PM BLDCM has been developed more and more rapidly and applied extensively, which gradually replaced other types of motors in many occasions. To meet the further development of BLDCM, position sensorless BLDCM emerged, which gradually replaced position sensor BLDCM and made the development and application of BLDCM step a new level.Aiming at the control key of position sensorless BLDCM-rotor position detection technology, on the base of ST7MC, this paper presented the solution of all-digital BEMF method. Replacing discrete analog filter with embedded digital filter, with 3-resistance input channel, this method avoided filtering delay and provided simple reliable hardware structure, with high sensitivity, high integration, minimum hardware cost, no signal attenuation and high signal to noise ration. Based on the analysis of the reasons of BLDCM torque ripple and the effect of different PWM carrier ways on motor commutation torque ripple, this paper optimized PWM carrier way to reduce commutation torque ripple. As the traditional PI regulation was very hard to satisfy a system's dynamic and static performance at the same time when regulating speed in closed loop, this paper adopted a kind of intelligent PI regulator with high response speed, small overshoot, excellent dynamic performance, strong robustness and parameters auto-tune ability to adapt many complex conditions, which improved the system performance.Based on ST7MC, this paper completed the software and hardware design of the position sensorless control system with high system integration, simple periphery design and low system cost, which still kept high control precision and performance.