Dual rotor electrical variable transmission for hybrid vehicles: Performance analysis with focus on losses over a driving cycle

摘要

An electrical variable transmission is a dual rotor electromagnetic device that can be used in hybrid electric vehicles to split the power to the wheels in a part coming from the combustion engine and a part exchanged with the battery. Since the power split is done in an electromagnetic way, no mechanical gears and corresponding friction losses are present. However the losses mainly originate from copper, iron, inverter and bearing losses. In this paper these loss contributions and their relative importance are calculated over a driving cycle, an analysis that can be used for further design optimizations. The loss models, that have previously been fitted on no-load measurements on a prototype machine, predict a mean EVT power split efficiency of 89% over the low power New European Driving Cycle. The main loss components and their origin are hereby discussed, and improvements are proposed.