Based On Sensorless Brushless Dc Motor Control System Research

DC motor has been widely used in the industrial field because of its flexible speed control and simple structure, but the traditional DC motor produce spark and a lot of noise in application because of the presence of the brush and the commutator motor, greatly reducing the life of the motor, brushless DC motor can overcome these shortcomings; so for this reason it has become the hot topic of this research, along with the new permanent magnetic materials and the development of power electronics technology, brushless DC positionless sensorless control motor getting rapid development, and has been widely used in various fields, studys on the control method of brushless DC motor sensorless control system has important practical significance.Firstly, The paper briefly describes the background and significance of the brushless DC motor, analyse in details the working principle and control theory of the brushless DC motor, build the mathematical model of the motor. Then, simulate brushless DC motor control system from position sensor and position sensorless in Matlab/Simulink. The idea of modular modeling system is divided into individual functional modules respectively: debug and ensure that each sub-module are correct, and gradually allow the merger of the sub-module; and then continue debugging until the entire simulation debugging system is successful. Mainly study the back-EMF zero crossing detection method, based on the traditional delay of30°-α commutation method, propose the delay of90°-α commutation to improve the traditional commutation method. The simulation results show that improved method gets good debugging results in the brushless DC motor positionless sensorless double closed-loop PI control system.Based on the simulation was able to design the hardware circuit of the control system, including opto-isolation circuit, and driver circuit over-voltage over-current protection circuit. Following the combination of motor drive requirements and control characteristics of the chip, selected were6N137as isolation chip opto-isolated circuit and IR21367drive chip design as driver circuit; and at the same time to ensure the safety of the driver chips, the driver circuit of overvoltage overcurrent protection circuit was designed. Since the rotor position signal detection circuit is a key part of the whole control system to achieve a zero-crossing detection of back EMF zero crossing detection through a virtual neutral point, a position sensorless control will be achieved as a result. The software design of control system adopted modular programming ideas, and completed the C language program under the Code Composers studio (CCS) software environment, repeatedly debug the entire control system, without increasing motor power supply, the hardware circuit carry out debugging, until the driver achieved correct chip output signal waveforms. The experimental results show that the designed control system can operate stably.