Brushless Motor Variable-speed System Research And Designing

ABSTRACTIn this paper the phase commutation and current curves of brushless motor variable-speed system are studied. According to the results that the pulsating torque is influenced greatly by the ratio of the direct current supply voltage and the electromotive force of the motor, an approach to reduce the pulsating torque is presented.A comparative study and simulation of different control schemes, for the brushless motor variable-speed system, is presented. The simulation results show that, with the outer speed loop based on conventional Proportional-Integral controller, the dynamic performance of the system is not content, while with Intelligence controller, the performance improves, and with Variable-Structure control with Sliding Mode, the system response influenced slightly by the vary of the system parameters. So it should be chose appropriate controller for the outer speed loop to fulfil the different variable-speed system.A simple brushless motor variable-speed system without position sensors is designed, it is based on MCS-80C196KB and frequency raising-lowering control is realized.