Dynamic winding reconfiguration of a brushless DC motor

The torque transient behavior during winding reconfiguration of a brushless motor is investigated in order to suppress torque interruptions or jolts. This reconfiguration changes the intrinsic torque-speed characteristic of the motor. A simpler approach using the alternation on and off (block commutation) of phase currents as well as an adaptation of the current amplitude depending on the transient state is presented. Integrated relays are used to switch from series to parallel star connection. Numerical simulations show the advantage of this approach. A test bench was developed and experimental measurements support the theoretical and numerical results.