The influence of topology selection on the design of EV/HEV propulsion systems

TLDR

The 42 V Powernet standard has driven extensive research into electric machine design for hybrid vehicles. This letter examines how a cascaded inverter topology can improve overall system and motor performance. The cascaded inverter boosts high‑speed power density of an induction motor by 73 % and, for an interior permanent magnet motor, raises low‑speed torque by 9 % and high‑speed power by up to 300 %, all without raising phase current.

Abstract

The adoption of the 42 V Powernet standard has focused substantial research effort into the design of electric machines for hybrid vehicles. This letter investigates the potential performance benefits afforded by adopting a cascaded inverter topology on the overall system and motor performance. As a particular design example, this letter shows that a cascaded inverter driving an open winding motor can increase the high-speed power density of an induction motor by 73%. For an interior permanent magnet motor, the cascaded topology can increase low-speed torque by 9% and high-speed power by up to 300%. In all cases, the power increase is achieved without increasing the phase current over a more traditional system.