State-space Model and Analysis of Motion-induced Eddy-current based on Distributed Current Source Method

This paper presents a distributed current source method to model the motion-induced eddy-current and its damping force. The proposed method, which relaxes two commonly made assumptions (negligible mutual induction and small vibration), discretizes the conductor into elemental vibrating current-density sources as state variables. The motion-induced eddy-current model has been formulated in state-space representation, and validated numerically with FEA; the results show excellent agreement. The model provides a basis to investigate the effects of mutual induction and vibration amplitude on the computation accuracy of the eddy-current and its generated magnetic flux density and damping force. The findings reveal existing methods (based on these commonly made assumptions) overestimating the peak damping force, and failing to capture high-order harmonic components and frequency effects on phase-shift. Results of a parametric study that investigates the effects of the PM aspect ratio and conductor skin-depth on the damping force are presented, providing essential bases for design optimization of EC damping system control applications.