Low Voltage Power Supply in Modular Multilevel Converter based Split Battery Systems for Electrical Vehicles

Usually the low voltage power supply in electric vehicles is generated out of the high voltage DC-BUS by a dedicated DC/DC converter. When substituting the conventional drive train/motor converter by a modular multilevel converter with split batteries, this DC-BUS is obliterated. In this paper we introduce an approach to generate this low voltage supply efficiently based on the modular concept. By adding just, a single capacitor based module to each converter arm, a solution for an efficient bidirectional energy exchange between the low voltage power supply and the traction battery can be realized. The comparison to state-of-the art solutions shows that the new approach enables an efficient integration not only of the low voltage power supply, but of any energy consumer and producer into split Battery Storage Systems. It will be shown by simulations and measurements on a first prototype, that an implementation based on that technology enables a power exchange in any operation point of the electrical vehicle.