Steady-State Analysis of Electric Machines Using the TP-EEC Method Based on Time-Periodic Conditions in a Rotational Reference Frame

Abstract

This paper proposes a new convergence acceleration method specialized for the magnetic field analyses of synchronous machines based on the time-periodic explicit-error-correction (TP-EEC) method. The proposed method constructs an auxiliary equation for error correction in the dq rotational reference frame to convert a fundamental harmonic component into a DC component. This conversion enables us to perform error correction using the TP-EEC method at intervals of an arbitrary number of time steps. The effective time intervals for error correction were investigated using practical interior permanent magnet synchronous motor (IPMSM) models. Moreover, DC superimposed problems, such as PMSMs with an open-end winding, were examined. Numerical results verified the effectiveness of the proposed method, and smaller time intervals could significantly improve the convergence characteristics of the transient analysis when high-order harmonic components were small. Furthermore, by adopting a 1/6 period as the time interval for the proposed method, a steady-state solution could be obtained precisely, even in a time-periodic problem that included many high-order harmonic components.