A High Efficiency Transmission Architecture for Electric Vehicles
2022-01-0792
03/29/2022
- Event
- Content
- A Dual Epicyclic Electronic Continuously Variable Transmission (DE-ECVT) with an input-split, output coupled, split-power-path configuration is proposed for improving overall system efficiency and range for electric vehicles. By modulating the power split ratio between the mechanical (i.e. Planetary Gear Trains) and electrical drivelines (i.e. Motor Generator Units), a continuous range of gear ratios that facilitate a higher efficiency powertrain is obtained. The proposed concept leverages two power-split units that leads to significantly reduced power flow through the electrical drivelines (compared with single speed EV transmissions as well as single power-split E-CVTs) while providing the same overall ratio spread for transmission operation. A multi-layered optimization is performed, first on the operational control strategy to maximize the end-of-cycle SOC (State of Charge) of the battery for a given set of transmission design parameters, and then subsequently on the design parameters to maximize the overall efficiency over multiple configurations of the given architecture. The performance of the architecture is bench-marked using simulation models derived from a Chevy Bolt baseline and the models are simulated against the highway (HWFET) and the urban (UDDS) driving cycles of EPA and an effective gain of 13.6 percent in the range is demonstrated. Stick-diagram schematic realizations of these concepts are also presented.
- Citation
- Swain, A., and Gopalswamy, S., "A High Efficiency Transmission Architecture for Electric Vehicles," SAE Technical Paper 2022-01-0792, 2022, .