Design Of Speed Control System For Permanent Magnet Brushless Dc Motor

The cultivation and development of electric vehicles is one of the measures to effectively alleviate the current situation of resource shortage and environmental pollution.As a new type of motor with excellent torque and speed characteristics,permanent magnet brushless DC motor can better meet the high performance control indexes required by electric vehicles for motor drive systems.Based on the software and hardware development of the control system,this paper studies the control method of permanent magnet brushless motor.This paper first analyzes the characteristics and advantages of permanent magnet brushless motor as a pure electric drive vehicle drive motor,and makes a difference analysis on the current selection of motors in the field of electric vehicles.The existing control methods and strategies of permanent magnet brushless motors are summarized and summarized.The high-performance control technology of permanent magnet brushless DC motors is analyzed for two key technologies: effective suppression of torque ripple and precise control of sensorless,which laid the theoretical foundation for the in-depth study of control strategies.Secondly,based on coordinate transformation,the mathematical modeling of permanent magnet brushless DC motor under two coordinate systems is realized.Based on the analysis of mathematical model,an improved direct torque control method for permanent magnet brushless DC motor and Hall signal compensation strategy based on Hall signal feedback control is proposed.The Hall signal is processed by the back-EMF zero-crossing signal.Correction to ensure a more accurate rotor position.,and analyzes the current control methods commonly used in direct torque control.Based on the MATLAB 2016 a simulation platform,the permanent magnet brushless motor simulation model was built,and the high-efficiency simulation in constant load acceleration/deceleration mode and cruise control mode was completed.The rationality of the improved strategy was verified.Furthermore,it provides theoretical support for the experimental research of the control strategy of permanent magnet brushless drive motor.Then,using MOSFET as the power switching device,the three-phase full-bridge inverter circuit of the permanent magnet brushless motor control system is designed.The driver circuit of the three-phase inverter is designed with IR2136 as the driving chip.The hall sensor signal inverting circuit is designed with 74LS14 as inverting device.Other control circuits are also designed,such as detection circuits without position sensors,overvoltage and overcurrent protection circuits,and power supply circuits.The designed main control circuit satisfies the requirements of the permanent magnet brushless motor control system,and in the CCS development environment,the permanent magnet brushless motor driver program is written in C language.Finally,a set of permanent magnet brushless motor speed control system was developed,and the hardware and software test of the control system was completed.The results show that the configured driver can achieve high-performance control of the permanent magnet motor,and the entire control system can accurately control the motor speed.The development of the hardware and software system of the motor control system provides conditions for the in-depth study of the control strategy of the permanent magnet brushless motor.