Control System Research Of Brushless DC Motor Without Position Sensor

Brushless DC motors not only include the advantages of traditional permanent magnet DC motors such as fast speed adjustment response and strong carrying capacity,but also use electronic commutators instead of mechanical commutation modes,which greatly reduces operating noise and does not change phase.During the process,sparks jeopardize the motor body.Therefore,brushless DC motors have important application value in the production activities of human beings in various fields.In order to accurately obtain the rotor position signal to complete the commutation and speed adjustment of the brushless DC motor,a position detection device is usually installed on the rotor.The rotor position detection device not only increases the cost and volume of the motor,but also because of external harmonic pollution on the position.The influence of the detection accuracy affects the control performance of the motor.Therefore,the research of the position sensorless control system has become a hot spot in the field of motor control.In this thesis,from the perspective of improving the performance of the position sensorless control system,an improved sliding mode observer is used to perform on-line real-time calculation of the rotor position,and an adaptive algorithm is used to estimate the rotational speed.This sliding mode observer constructs a new type of switching function to replace the traditional symbolic function,so that the motor control system can obtain a smooth back-EMF observation without additional low-pass filter and phase compensation module,and then obtain the rotor position.Using Lyapunov stability theory,a model reference adaptive algorithm is designed to estimate the rotational speed,which is independent of the switching ripple.The simulation of MATLAB/Simulink platform verifies the effectiveness of the proposed method.In order to improve the reliability of sensorless control system,a brushless DC motor with sensorless control system based on MSP430F149 processor and STC15W404 microcontroller is produced.The main and auxiliary operation modules of the system can work together to provide more basis for commutation.The drive unit can ensure stable operation of the motor through single-bridge or double-bridge operation.One of module or circuit is damaged,another module or circuit can still independently operate.A motor control system based on MSP430F149 processor and STC15W404 microcontroller was established.Experiments were conducted on an experimentalplatform.The effectiveness of the proposed method was verified by experiments.