Reconfigurable Battery Architectures for Electric Aircraft

In order to support the growing market and research in the field of electric propulsion for aircraft, a novel approach has been identified in designing an electric propulsion chain. A reconfigurable battery system that can adjust its output voltage with the resolution of a single cell voltage has been developed and analyzed. The underlying rationale was to increase the efficiency of the motor controller during partial load phases of a flight by lowering the battery output voltage and subsequently forcing the motor controller to operate at a higher duty cycle. Furthermore, a dedicated battery charger is obsolete due to the battery system's ability to synchronize itself with an external AC or DC power source and withdraw power from it. Additional focus lies on maximum system reliability and research for methods to precisely measure each cell's state of health way beyond the capability of a conventional battery management system. Ultimately, individual cells with a lower capacity or faulty cells, including catastrophic cell failure, can be bypassed without compromising the overall functionality of the battery system. This publication presents the results and architecture for a propulsion chain with a nominal system voltage of 400 V and 80 kW of electric power.