Comparison of efficiencies depending on excitation angle of a square-wave brushless DC motor

Abstract

　There is a method to excite by a square wave as a simple method of the brushless DC motor drive. The simplest method is 120 ° excitation method used the Hall sensor output. But the method has part inferior in terms of efficiency. However, the efficiency can be clearly improved by extending excitation angle or advancing current phase angle, in spite of square wave excitation. In this paper, we measure the motor efficiency using these methods, and inspect their validness experimentally.