A novel changeover technique for variable-winding brushless DC motor drives

For most electrical vehicular systems, there exists a tradeoff problem for the motors between large starting torque to enhance acceleration and climbing ability and wide constant power range to increase cruising distance. The method of winding switching over for various motor configurations has been extensively proposed in the literature. However, a dead time has to be inserted during changeover operation. In the paper, a novel changeover technique for variable-winding brushless DC motors with the application to electric scooters is presented. The dead time is eliminated during the winding configuration changed from wye to delta or vice versa. This scheme both protects the related hardware and preserves the speed performance. The experimental results will demonstrate the effectiveness.