Investigation of End Winding Vibration Characteristics, Insulation Failure, and Protection in FESS

The permanent magnet synchronous motor/generator serves as the critical component for energy conversion in the flywheel energy storage system (FESS), and stator end winding insulation constitutes the important factor affecting system reliability and lifespan. Through the-oretical analysis, finite element analysis, and experimental verification, this article studies the vibration characteristics and insulation damage of end windings in FESS. First, the coupling model of end winding vibration is established considering the stator magnetic pull per unit area (MPPUA) and winding electromagnetic force (EF), and the stress intensity factor (SIF) is introduced to characterize the insulation damage behavior. Then, the vibration of the winding during charge, standby and discharge of FESS is calculated by field-circuit coupling and multiphysics coupling analysis, and the experimental verification is carried out. Finally, the SIF analysis of the crack is carried out using the transient structure field, and the experimental equipment is set up to complete the strain measurement of different end winding parts and the local reinforcement analysis. The methods and results of this article provide reference and guidance for the design, manufacture and maintenance of FESS.