Implementation of a bidirectional DC-DC in electric powertrains for drive cycles used by medium duty delivery trucks

Different powertrain topologies have various advantages and disadvantages when used in electric vehicles. In this paper, the efficiencies of two different powertrains are compared. Both designs use a 2 level inverter and a surface mounted Permanent Magnet Synchronous Motor (PMSM). In the first design the inverter is directly powered by a high voltage battery and is operated using traditional pulse-width modulation (PWM). In the second design a bidirectional DC-DC is used to connect a lower voltage battery to the inverter and is operated using a variable DC link voltage strategy. These two systems are referred to as S1 and S2, respectively. The powertrains are designed to operate a class 4 delivery truck, which is driven by one motor attached to each rear wheel assembly. The efficiency maps of these systems are examined in the context of different drive cycles for a delivery truck. Furthermore, standard and experimentally captured drive cycles are compared and the results demonstrate the conditions under which system S2 is most effective.