Unified power-based analysis of combustion engine and battery electric vehicle energy consumption
2022-01-0639
03/29/2022
- Event
- Content
- In previous work we have shown that fuel power consumption of Internal Combustion Engine Vehicles (ICEV) is proportional to vehicle traction power, across vehicle and engine sizes and across different drive cycles, for a given technology. This results from the linear transfer function between powertrain input (fuel) power and output (mechanical) power at moderate power levels. In this paper we extend the analysis to battery electric vehicles (BEV), which differ from ICEV in several respects in terms of energy consumption. ICE engines have unidirectional power flow, while BEV electric motors have bidirectional power flow capability, and the battery provides reversible energy storage. This enables the recuperation of vehicle kinetic energy during braking. As a result, the net energy needed to drive through a cycle is reduced. Additionally, the BEV accessories are driven directly from the battery energy source and not by the powertrain as in ICEV. But critically, the electric motor, like the IC engine, is shown to have a linear transfer function between input and output at the moderate loads experienced in most driving. We find that, provided one accounts for these system differences, the BEV, like the ICEV, has a linear transfer function between battery power and vehicle traction power. The ‘top-down’ vehicle results align with the ‘bottom-up’ powertrain data. This makes it a powerful tool to interpolate available but incomplete data to different vehicle variants or drive cycles. It enables analytically derived estimates for BEV energy consumption and range, which are analogous to ICEV Analytically Derived Fuel Economy (ADFE) estimates. This work combines known analytical methods and a growing public industry BEV energy consumption database to develop a first principles model which shows the sensitivity to basic vehicle design parameters such as weight and road load. Analytically derived range estimates for variants, based on the measurement of a base vehicle, are then possible. This can potentially streamline BEV range and energy consumption testing requirements.
- Citation
- Phlips, P., Megli, T., and Ruona, W., "Unified power-based analysis of combustion engine and battery electric vehicle energy consumption," SAE Technical Paper 2022-01-0639, 2022, .