Semi-Analytical Calculation of AC Copper Loss in Flat Wire Windings Considering PWM Harmonics

Abstract

This paper proposes an AC copper loss calculation method for flat wire windings of pulse width modulation (PWM) driven permanent magnet (PM) synchronous motors. To quickly account for the effect of high frequency current harmonics on the magnetic field and losses, a semi-analytical eddy current loss calculation method is developed. This method combined the two-dimensional (2-D) quasi-static finite element method (FEM) with the frozen permeability method and the superposition theorem to rapidly calculate the slot leakage magnetic field caused by PWM. The time-harmonic field distribution is obtained from the quasistatic field results combined with the Maxwell's equations, and the losses in the flat wires are calculated using the Poynting theorem. The proposed method has been validated using FEM. The calculation method features a good tradeoff between computational speed and accuracy, making it suitable for calculating copper loss and optimizing motor efficiency.