Speed control of SVPWM inverter fed BLDC motor drive

Abstract

Brushless DC motors have a very wide area of applications due to their higher efficiency and easy control strategies. For controlling the BLDC motors we use three phase bridge converters. In BLDC motors only two phases are supplied and the third phase is kept off. Which two phases are to be supplied is determined on the basis of the position of the rotor. Based on the position of the rotor, switching devices in the inverter are commutated for every 60 degree. Rotor position sensors are used to sense the position of the rotor at every instant of time. For controlling the output voltage and frequency of the inverter Pulse Width Modulation (PWM) techniques are used. Sinusoidal PWM and Space Vector PWM (SVPWM) are the most used techniques today. Sinusoidal PWM is the simplest and most used PWM techniques today, but it has many flaws. The newly invented Space Vector PWM technique reduces these flaws such as it reduce switching loses, harmonic content in the output, better utilization of available dc-bus voltages. This thesis presents PI controller for the speed control of BLDC motor fed by a SVPWM inverter. The PI controller leads to improve the behavior of the motor. The use of SVPWM inverter reduces the size of the battery or power source. The SVPWM technique for inverter and speed control for BLDC motor is simulated using Matlab software package.