A Lightweight, High-Speed Kinetic Battery for Hybrid and Electric Vehicles

This paper presents the conceptual design of a lightweight and high-speed kinetic battery to capture the braking energy and provide thrust for electric or hybrid vehicles. By acting as a high-power buffer, the proposed kinetic battery is intended to improve drive range, main battery life cycles, and to downsize vehicle powertrains. It is designed to store and release braking energy of a mid-sized vehicle (573Wh), with a flywheel only weighs about 11.2 Kg. The flywheel, which has a maximum spin speed of 50,000 revolutions per minute (RPM), is composed of shells/rims of high strength steel and composite materials that are designed and validated by finite element analysis (FEA). The novel hybrid, multi-rim and multi-material rotor design yields a higher energy density and less weight than the conventional single or multi-rim design. In addition, a five-degree-of-freedom (5-DOF) magnetic bearing system is incorporated to provide frictionless support.