Fast Calculation of Strand Eddy Current Loss in Inverter-Fed Electrical Machines

Abstract

This paper investigates the complex the slot leakage magnetic field and the strand eddy current loss in windings of inverter-fed electrical machines. It shows that the magnetic saturation and the pulsewidth modulation (PWM) harmonics could have a significant influence on the slot leakage magnetic field, thus may influence the eddy current loss. To consider these effects while reducing the computation burden, a semi-analytical strand eddy current loss calculation method is proposed based on the slot leakage field calculation by 2D magnetostatic finite element method (FEM) and a 2-D analytical high-frequency eddy current loss expression. The frozen differential permeability method (FDPM) and the linear time-harmonics FEM are used to fast calculate the PWM-induced slot leakage field with the magnetic saturation considered. Besides, a conductor position model is used to extract the conductor coordinates and leakage field information for calculating the eddy current loss. The proposed method is implemented and experimentally validated on a surface-mounted permanent magnet (SPM) electro-mechanical actuator (EMA) fed by a PWM inverter for aircraft application. It shows high calculation accuracy and fast calculation speed, which is suitable for motor-inverter system design and optimization.