A Novel Brushless Permanent Magnet Motor for Electric Scooters

The purpose of this study is to design brushless permanent magnet DC motors for electric vehicles based on a pole-changing method. By generating a pulse when changing the number of poles, magnetization of magnets can be changed appropriately and the principle of pole-changing motors can be applied to permanent magnet machines. This kind of machine not only retains the feature of permanent magnet machines in efficiency, but also acquires wide speed range. In this study, a pole-changing method using common windings is proposed and performance of brushless permanent magnet DC pole-changing motors is investigated. According to T-N curves, the proposed brushless permanent magnet pole-changing motor yields larger starting torque and wider speed range than motors with a fixed number of poles.