Research Of Efficient Drive Control Technology For Brushless DC Motor

Brushless DC motor (BLDCM) not only has a series of advantages that AC motor owns, likesimple structure, reliable operation, convenient maintenance and so on, but also has manycharacteristics of DC motor, such as operation efficiency, small excitation loss and good speedadjusting performance, which has made it develop and popularize at a very fast speed. In the limitedenergy supply systems, such as aerospace and automotive industries, which power is larger, efficiencyand reliability are higher required. Therefore, research of efficienct control for BLDCM is enssential.This paper focuses on BLDCM drive efficiency, carried out the research of efficienct drive controltechnology for BLDCM. The main research contents and conclusions are as follows:On the basis of explaining the background and significance of this thesis and describing thedomestic and external research status, the paper explicitly analyzes the basic structure, workingprinciple and mathematical model of Brushless DC motor. A brushless DC motor drive systemsimulation model is built based on the Matlab/Simulink software, and a set of Brushless DC motorcontrol system is established using TMS320F2812DSP of TI company as the main control chip. Theexperimental prototype and simulation model has a good degree of agreement.A comprehensive analysis of inverter circuit losses and motor losses is made upon brushless DCmotor control system. Aiming to rueduce the inverter circuit losses, a novel drive system of the maincircuit and its control method is used. The switching loss and freewhelling loss is reduced by using thebidirectional cascade Buck-Boost circuit and synchronous rectification technology. Phase current inthe new system is smoother, which could eliminate freewheeling loss, reduce switching loss and ironloss, suppress torque ripple, achieveing efficient driving control.As to improve the drive efficiency of the running motor, this paper studied the influence ofdifferent drive strategies have on the drive efficiency. In introducing the space vector pulse widthmodulation (SVPWM) principle, the control program is wrote and the sine wave drive control ofbrushless DC motor is realized. The experiment results showed that, compared to PWM driving,efficiency of minimized switching loss SVPWM driving increased by1.5%and efficiency ofconventional SVPWM driving increased by2.5%.In order to further improve the drive efficiency, the regenerative braking control technology isused. Based on analysis of control principle and modulation mode, mathmematical models underdifferent modulations are deduced. In the view of large inverter circuit losses of the traditional constant torque regenerative braking mode, a new method of regenerative braking control based onsynchronous rectify technology is put forward. Simulation and experimental results show that the newstrategy can not only improve efficiency of energy feedback but also decrease braking time.