Open-ended induction motor drive with a floating capacitor bridge at variable DC link voltage

The open-ended winding configuration allows feeding an electric motor from two sides. If one of them is connected to an inverter closed on a floating capacitor, operating as an active power filter, it is possible to obtain several benefits over the traditional configuration, such as an extended field weakening speed range and a lower current ripple. However, the additional converter causes switching losses that reduce the total efficiency of the drive. In this paper, it is shown that in induction motors it is possible to improve the efficiency of the open-ended drive by controlling the DC-link voltage of the floating bridge depending on the operating conditions. Experimental results are shown to confirm the effectiveness of the developed solution.