The Study Of The Control System For Permanent Magnet Brushless DC Motor

Brushless DC motor (BLDCM) with permanent excitation, in which electricalcommutator is used instead of mechanical, has not only the same good characteristics ofspeed control as traditional DC motor, but also the good characteristics of AC Motor.Brushless DC motors have found wide application due to their high power density and easeof control. Moreover, the machines have high efficiency over wide speed range. Recently ithas been quickly developed. Due to permanent magnet rotor and its inherent restriction for flux-weaken operation,it is difficult of BLDCM to operate above the base speed. A novel idea, whose kernel is theinstantaneous reactive power theory, is introduced for BLDCM field-weakening scheme. Inpractice, increasing s/ω has a field-weakening effect and results in increased motor speed.Simulation results show that the overall of this method is the enhancement offield-weakening performance of drive and a reduction in torque ripple compared theconventional method. This paper introduces a control system which uses a DSP to control the commutationand speed of BLDCM. The basic structure, operational principle and design method of thissystem are set forth in this paper. The thought of hardware design and softwareprogramming is introduced as well. The modularized design is used in software system. Itmakes the system easy to improve and debug. In addition, this paper studied the problem ofElectro Magnetic Compatibility (EMC) for the control system. The results of the experiments show the proposed speed control solution for BLDCMis feasible. It has excellent operation performance as well as high reliability, debuggingeasily. At the same time, the system also has strong expansibility, portability and high usevalue.