EMF BASED SENSOR-LESS SPEED CONTROL OF BLDC MOTOR USING A TWO STAGE AC-DC CONVERTER

Abstract

This paper presents an AC-DC converter for speed control of a Brushless DC(BLDC) Motor. This 
model consists of two stages in which, the first stage is an AC-DC converter also known as a diode bridge 
rectifier and the second stage is the DC-DC buck converter. A dc-link capacitor couples the two stages which 
is used to eliminate the ripple present in the output of the rectifier. In order to control the speed of BLDC 
motor, it is important to know the rotor position. This paper illustrates the use of an emf-based sensor-less 
control technique for rotor position detection. A PWM based feedback control loop is used to regulate the 
output of buck- converter which controls the output of BLDC Motor. This technique has been implemented 
for the speed control of a brushed DC Motor but now-a-days there are a large number of applications for 
BLDC motor. So, an efficient speed control system is essential. Sensor-less speed control technique 
overcomes the drawbacks of sensor-based control technique such as temperature sensitivity and higher costs. 
Hence, this paper presents the implementation of sensor-less control to control the speed of BLDC motor 
using MATLAB/SIMULINK.