On the feasibility of switched stator windings in permanent magnet motors for traction drives

Today inverter-fed permanent magnet (PM) synchronous motors may be considered as an alternative to squirrel cage induction motors. Higher efficiency and compactness can be achieved combined with lower inverter rating for the same output power. In this paper, two methods are considered to increase the available speed range. They are field-weakening and switched stator windings. It is evaluated how switched windings can be implemented and what influence they have on the motor design. As possible switch solutions, contactors and thyristors are examined. The resulting jerk is investigated experimentally and can be diminished sufficiently.