Analysis and optimization of a novel energy storage flywheel for improved energy capacity

TL;DR

This paper explores the design and optimization of a novel shaftless flywheel energy storage system, demonstrating it can significantly improve energy density compared to traditional designs through stress analysis and finite element optimization.

Contribution

It introduces a shaftless flywheel design approach and provides a simplified analysis method, enhancing energy density and integrating magnetic bearing and motor considerations.

Findings

Shaftless flywheel doubles energy density compared to traditional designs.

Finite element analysis optimizes the shaftless design with magnetic bearing and motor considerations.

Simplified analysis method aids in designing rotor-shaft assemblies.

Abstract

Kinetic/Flywheel energy storage systems (FESS) have re-emerged as a vital technology in many areas such as smart grid, renewable energy, electric vehicle, and high-power applications. FESSs are designed and optimized to have higher energy per mass (specific energy) and volume (energy density). Prior research, such as the use of high-strength materials and the reduction of stress concentration, primarily focused on designing and optimizing the rotor itself. However, a modern FESS includes other indispensable components such as magnetic bearings and a motor/generator that requires a shaft. The shaft significantly impacts the flywheel design. This paper investigates several typical flywheel designs and their stress analysis. A simplified analysis method is given for designing rotor-shaft assembly. It is found that the shaftless flywheel design approach can double the energy density level when compared to typical designs. The shaftless flywheel is further optimized using finite element analysis with the magnetic bearing and motor/generators' design considerations.