Abstract
The paper describes a cost-effective e-axle technology which offers high boost power using low electrical power and low voltage. Downsizing of the electrical system is enabled by using a low-cost compact solid steel flywheel. The power of the flywheel and electrical machine are combined using an innovative powersplit setup which can amplify the electrical power up to a factor of 5, both in propulsion and braking regeneration mode and dependent on operating point. As a result, a maximum power rating of 60 kW is offered still using only a 10kW, 48V electrical system. The powersplit system is compact and highly efficient, since the majority of the transmitted power remains in the mechanical domain. The following R&D questions related to this revolutionary new hybrid concept are addressed in this paper: • How to design a mechanically compact and safe rear-wheel flywheel KERS drive? • How to design the energy management system of the 48V battery and the flywheel? • How to design driving modes such as performance and fuel economy modes?
KEYWORDS – Flywheel hybrid, KERS, 48V, powersplit, dual energy storage