System Loss Measurement of a Novel Outer Rotor Flywheel Energy Storage System

The paper addresses a novel outer rotor flywheel energy storage system. A concept for non-invasive efficiency measurement approach and the necessary data acquisition system is described. The measurement results of a full size system are shown and discussed. They show that the current prototype has a maximum conversion efficiency of 96.4% although the inverter operation mode is not ideal. These measurements are used to validate an analytical loss model of the flywheel that is used to optimize the system. The optimization results show that significant improvements regarding efficiency and energy density of the flywheel are possible.