Research And Implementation Of Brushless DC Motor Servo System

Permanent magnet brushless dc motor occupies an important position in the field of industrial control, with small size, light weight, high efficiency and low inertia and other fine features. In addition, the dc motor not only has the excellent speed characteristics, but also has the electronic commutation means instead of the traditional mechanical brush dc motors,which are widely used in industrial fields of CNC machine tools, robots, servo control systems. With the rapid development of modern science and technology, it has put forward higher requirements for permanent magnet brushless dc motor control performance.Therefore, the study has a very important significance.But in practical applications, torque ripple of BLDCM, is one of the difficulties which are inevitable. The system in which use direct torque control strategy can get a better performance. The PID algorithm is used commonly in the Industry, but it can't provide the more precise control effect with the poor interference resistance and the weak load adaptability. So the sliding mode control algorithm is designed respectively in the speed and position servo system.The papper elaborates the working principle of brushless dc motor and the principle of direct torque control, further puts forward the control scheme of the system. At the same time, the paper designs sliding mode control algorithms based on the system state equation for the speed and position closed-loop of the brushless dc motor. The papper makes the simulation operation in both no-load and load cases, and compares the simulation results.The simulation results show that the design scheme of the papper can effectively restrain the torque pulsation phenomenon, static and dynamic performance of the system is well with the fast response, the good robustness. With the advantages of superior dynamic performance and anti-interference, it has a certain practical value and is worth promoting. With the combination of simulation, the paper designs the hardware system based on DSP, including the main control circuit, signal isolation drive circuit, current and position detection circuit,and completes the design process of the software system, building foundation for servo control of the follow-up study.