Study of Soft Switching Converter for Brushless DC Motor Drive

Abstract

Permanent magnet (PM) brushless DC motors (BLDCM) are generated by virtually inverting the stator and rotor of PM DC motors. The ‘DC’ term does not refer to a DC motor. These motors are actually fed by rectangular AC waveform. The advantage of these motors is the removal of brushes, leading to eliminate many problems associated with brushes. Another advantage is the ability to produce a larger torque because of the rectangular interaction between current and flux and an increase in electric loading with higher power density. Within the last decade, the research and development on BLDCM drives have been focused on the motor topology design and optimization as well as the motor control strategies. Nevertheless, most of these converter topologies employ the hard-switching technique which causes high switching losses and severe electromagnetic interference. Recently, a number of soft-switching techniques, providing zero-voltage switching (ZVS) or zero-current switching (ZCS) condition, have been successfully developed. Surprisingly, the development of ZVS soft-switching converters for BLDCM drives has been very little. Until recently, a few studies on soft-switching converters for BLDCM drives have been carried out. In this thesis, soft switching technique using IGBT’s is applied for Brushless DC Motor. Its principle of operation and simulation results will be given. It possesses some definite advantages over hard switching including improves the motor torque, speed of motor high switching frequency, high power density and high efficiency. The simulation model is developed using the most commonly used MATLAB/SIMULINK environment. The reason for choice of MATLAB/SIMULINK as a development tool is because it is the most important and widely used simulation software and is an integral part of taught program in most of the universities in electrical/electronic/computer engineering courses.