Battery voltage optimization of a variable DC bus voltage control powertrain for medium duty delivery trucks for various drive cycles

Abstract

One of the most commonly used electric drive topologies for electric vehicles is that of a permanent magnet motor powered by a two-level inverter and a high voltage battery (system S1). An alternative to this topology is to replace the high voltage battery with a low voltage battery and a DC-DC boost converter (system S2). Previous work has shown that such a design is beneficial for vehicles that usually follow daily drive cycles with low average speed and many start and stop cycles. One category of vehicles that meet these criteria are medium duty delivery trucks. It has been demonstrated that the target modulation index of system S2 can be optimized in order to minimize the energy consumption over a specific drive cycle. This paper focuses on the effect of the battery voltage on system efficiency and demonstrates that the battery voltage can be used as an optimization parameter along with the previously studied target modulation index.