Finite-Element Based State-Space Modeling of AC Winding Losses in Synchronous Machines

Abstract

This paper proposes a finite element (FE) based state-space model for evaluating AC winding losses in synchronous machines to be implemented in Simulink. The model is constructed by storing multiple static FE solutions into lookup-tables to express the magnetic vector potential on the boundaries of the stator slot region as a function of stator currents and rotor position. The geometry-dependent FE matrices derived from the slot mesh are computed only once, while the dynamic simulation evaluates AC winding losses at each time step based on the instantaneous operating conditions. The model allows using arbitrary voltage excitations such as sinusoidal and pulse-width modulated supplies seamlessly without the need of pre-computing the harmonic content of the current waveform. Proper orthogonal decomposition is used to reduce the model complexity and speed up the simulation. The Simulink implementation of the proposed AC winding loss model shows good agreement with the time-stepping FE simulation results, while achieving a 60-fold speedup in computation.