Design and Multiphysics Analysis of Medium-Low Speed Flywheel Energy Storage System with Dual-Rotor Toroidal Winding

This paper proposes a novel low and medium-speed flywheel energy storage system (FESS) based on the dual-rotor toroidal winding permanent magnet synchronous machine (DTPMSM). The design of double-layer toroidal windings significantly reduces the length of end windings and the copper losses without compromising electromagnetic performance. The consequent flattened flywheel configuration enhances rotor dynamic performance, thereby improving the reliability of the magnetic bearing system. Simulation and prototype experiments validate the feasibility and performance advantages of the proposed design.