Application of a bidirectional DC-DC in an electric powertrain for medium duty delivery trucks

The efficiency of electric powertrains is of great importance for the electrification of transport. In this paper, the efficiencies of two different powertrains are compared. The first design uses a traditional pulse-width modulation (PWM) battery-powered inverter with a high voltage battery pack. In the second case, the battery is connected to a bidirectional DC-DC converter and a variable DC voltage is produced and fed into the inverter. These two systems are respectively referred to as S1 and S2. Both systems are used to power the same surface mounted Permanent Magnet Synchronous Motor (PMSM) and are designed to operate a class 4 delivery truck. The truck is designed to be driven by one motor attached to each rear wheel assembly. Furthermore, the efficiency maps of these systems are examined in the context of a standard drive cycle for a delivery truck.