Current Control Strategy for Dynamic Winding Reconfiguration of Slotless Brushless DC Motors

Depending on the winding configuration, the intrinsic characteristic of a motor differs. By reconfiguring the winding, it becomes possible to increase the torque-speed limitation of a motor. Current proposed methodologies for dynamically reconfiguring the winding suffer from important torque jolts during the reconfiguring process if the inductance of the motor is low. In order to guarantee a constant torque, the transient behavior is investigated when the winding is reconfigured from series to parallel or from star to delta configuration. A novel approach combining a fine control of the current amplitude and the commutation angle is presented. Numerical simulations attest to the exactness of the approach and experimental results substantiate the simulated model.