48V traction: Innovative drive topology and battery

This paper introduces an extra-low voltage drive topology. In contrast to the current trend to higher DC voltages in BEVs (400 V, 800 V), ISCAD (Intelligent Stator Cage Drive) is based on a voltage level of 48 V. From today's perspective, a power of 200 kW or more is feasible. For all components included in the electrical drivetrain such as machine, power electronics and battery, a rethinking as well as a redesign is necessary. However, several advantages can be achieved with this system: reduced costs and increased efficiency compared to a conventional HV system as well as intrinsic safety due to low operation voltage. A 48 V traction battery with a similar capacity compared to a HV battery requires a cell configuration with a high number of parallel connected cells. The second part of this paper investigates the impact of a high parallelization in theory as well as on the testbench. Advantages such as reduced balancing effort and slightly increased lifetime can be shown for a highly parallel setup. Capacity, energy and efficiency of an exemplary battery pack were measured and compared for series and parallel configuration. The measurement results fit with the theoretical analysis.