Energy Efficiency of Battery Electric Vehicles with In-Wheel Motors 13-04-01-0002

Battery electric vehicles (BEVs) with in-wheel motors (IWMs) are a rapidly emerging technology. BEVs lie in a wide power interval and are of different types. This article considers BEVs lying in the power interval of [0.25-360] kW and groups them into five classes. The energy efficiency of a BEV is a determinant of its operational cost and environmental impact. A graph of energy efficiency versus power is important while investing in new BEV technologies. In constructing this graph over the said power interval for single motor drive (SMD) BEVs, the existing literature on energy efficiency provides some data for two of the five classes, while for IWM BEVs, the literature provides some data for just one value of power. To construct these graphs for both SMD and IWM BEVs, this article, as its primary contribution, performs a comprehensive study of each class of BEV to gather realistic data for each stage involved in the calculation of their energy efficiencies. It concludes that the tank-to-wheel energy efficiency of an IWM BEV may be up to 18% higher than that of an SMD BEV of the same power. To see how efficient the BEVs are with respect to internal combustion engine (ICE) vehicles, this article, as a secondary contribution, concludes that the well-to-wheels energy efficiencies of IWM BEVs, SMD BEVs, and ICE vehicles, each of around 80 kW, are about 33%, 30%, and 18%, respectively for natural gas pathway.