Research And Design Of Brushless DC Motor Control System Based On DSP

With the development of power electronic technology and digital micro processor technology,brushless DC motor control technology has been greatly improved,especially in the efficiency,noise and torque ripple.BLDC motor has been widely used in new energy vehicles,high speed trains and small electric vehicles.So the brushless DC motor controller should have higher control accuracy,lower torque ripple,faster response speed and optimized control algorithm.On this background,the resolver is selected as a sensor to detect rotor position and speed more precisely.Then we research relative strategies to obtain lower torque ripple,and design the closed loop control algorithm to get better control effect of the speed and current.This paper mainly designs a brushless DC motor control system based on DSP of TI company,and use the resolver to detect the rotor position and rotor speed.The introduction mainly describes both background and significance of the research,and list several products and control technology of both domestic and international company.In the second chapter,using MATLAB build BLDC model and phase sensitive demodulation algorithm model to guide to optimize DSP software.The third chapter focuses on the analysis of both the reason of the torque ripple and suppression strategies.A torque rippple suppression strategy based on PWM_ON_PWM modulation mode and current prediction algorithm is proposed to improve the torque ripple suppression effect.Hardware circuit of the control system is designed in the fourth chapter,including BLDC motor drive circuit,resolver demodulation circuit,DSP controller and power supply circuit.The fifth chapter completes the system software and each module program.Resolver digital demodulation,current loop and speed loop digital PID algorithm are the key points of software.In the sixth chapter,current loop and speed loop PID and the current prediction algorithm are tested.Finally,summarize and prospect are maked.The research results show that the precision of rotor position can be achieved by using the resolver as the detecting device of the motor rotor position.The precision can reach to 0.08 degrees and it can be used to compensate the commutation degree accurately.The torque ripple can be reduced to 5% by using the PWM_ON_PWM chopper method and current prediction algorithm.Through experiments,the design of digital PID algorithm can obtain good dynamic and steady state performance in the control of current and speed.