Basic design of 1kWh class compact flywheel energy storage system - application of active magnetic bearings with zero-power nonlinear control method

摘要

In the development of a flywheel energy storage system (FESS) that provides a rated power for several hours, mechanical and electrical losses of the FESS become a crucial point. Therefore, this paper presents the specifications in terms of losses for active magnetic bearings (AMB) and motor/generator. The total loss of a conventional FESS and the methods to reduce almost quarter in the total loss, are presented. The point of improvement is mainly the reduction of the AMB loss by using zero-power nonlinear control. This control method avoids the bias currents, which cause the rotational loss of the AMB and the power consumption of the AMB controller. On the other hand, the rotor system's dynamic analysis are calculated in order to guarantee a stable rotation of the rotor including flywheel. As the result, it is possible to conclude that unexpected vibration of the rotor caused by bending mode natural frequencies will not occur at the rated rotational speed. The basic design of the 1 kWh class compact flywheel energy storage system (ComFESS) that is able to supply the energy of 300W during 3 hours, has been completed.