Rotor position control of brushless dc motor by using various control strategies

Abstract

Brushless DC motors (BLDC) are mostly used in industries, aerospace and home appliances due to their high power density, high efficiency and ease of control. These motors are usually controlled using a three phase voltage source pulse width modulated inverter bridge. For starting of brushless dc motor, proper switching logic sequence is to be provided to turn on and turn off the power semiconductor devices used in the voltage source inverter bridge with respect to rotor position of the BLDC motor. Rotor Position of the BLDC motor is sensed by using Hall sensor. Based on the rotor position, the power semiconductor devices are switched on and off consecutively every 60 degrees. To attain the desired level for performance, the BLDC motor needs appropriate rotor position controllers. In case of brushless DC motors, generally rotor position control is attained by using Proportional Integral Derivative (PID) controller. Although traditional PID controllers are extensively used in the industry due to their simple control arrangement and ease of implementation, these controllers create difficulties where there are some control complexities such as load disturbances, parametric variations and nonlinearity. In addition, PID controllers need accuratelinear transfer function model of the system under control. This thesis presents an optimization of PID controller using Genetic algorithm, Particle swarm Optimization and Gray wolf Algorithm. Five objective functions are considered for tuning of PID controller such as Root mean squared error, Integral of absolute error, Integral of time multiplied newline