Research On Sensorless Brushless DC Motor Speed Control System

Generally brushless DC motors use the rotor position sensor to obtain the rotor position signal and then control the motor commutation, but the use of the sensor control has a lot of drawback, such as the stability of the system is poor, the sensor is easily impacted by the work environment, its use is subject to certain restrictions, while the use of the sensorless control technology can solve these problems, so the brushless DC motor speed control system without position sensor is studied in this article. Specifically includes the following contents:First, the paper introduces the background and significance of this topic, discusses the development situation of brushless DC motor, introduces and contrasts the control modes of brushless DC motor- the sensor control and sensorless control in detail. Its basic principle, structure, mathematical models and speed adjust methods are studied.Second, the design of the control system overall program is completed, including several elements: The dual-loop control strategy is verified; For the current control chips and controllers, DSP TMS320F2812 chip is selected as the main chip of the system; After analyzing the current rotor position detection method, the principle and commutation logic of the the Combination of back EMF superposition and back-EMF zero crossing are introduced; Compar the traditional PID control, the digital PID algorithm and a new PID algorithm selection algorithm,the digital PI control algorithm is chosen; The three-stage startup is selected.Third, the simulation model of Brushless DC motor control system is set up by using the MATLAB / Simulink software, and the simulation of control algorithm and strategy is done. And it describes the process of establishing each module.Simulation is done for the selected system.Finally, according to the requirements and the overall program of the control system, the hardware experimental platform of the control system is designed, including a main circuit, a rotor position detection circuit, a voltage and current sampling circuit and the isolation circuit; The software part of the system is designed by C language, including the main program、subroutines、interrupt service program and other programs.