Spectral inductance of the linear motor‐space harmonic analysis

Abstract

PurposeThe aim of the paper is to present the methodology of obtaining an approximate equivalent circuit composed of lumped parameters which describes an electromagnetic state of induction machines (IMs) with solid secondary. Higher space harmonic field components are taken into account. The proposed method of machine model constructing is useful for solving electrodynamics states of solid secondary IMs, as well linear machines.Design/methodology/approachA determination of equivalent circuit parameters of a polyharmonic machine is divided into two steps. In the first step, frequency plots of the spectral inductances are derived – for each of the space harmonic components – from an electromagnetic field distribution calculated by means of the finite element method. In the second step, each of the spectral inductances are represented by the operational inductances which corresponds to the equivalent circuit composed of parallel connected the magnetizing inductance and branches consisting of resistance and inductance connected in series.FindingsThe proposed method allows the construction of the approximate equivalent circuit with lumped parameters which enables to solve electrodynamic states of solid secondary IMs, as well linear machines. The machine model has been derived with consideration of the higher space harmonic field components.Research limitations/implicationsSaturation effects of a magnetic circuit and an unbalance of phase currents have not been taken into account.Originality/valueThe paper shows the method of constructing a machine field‐circuit model. Lumped parameters of the model have been derived using frequency characteristics of the stator spectral inductance with consideration of the higher space harmonic field components.

Speed and rotor flux estimation based on the induction machine inductance frequency characteristic - simulation studies

“…A system frequency characteristic determines the response of the system excited by a sine wave whose frequency changes in a specified range. In the case of an induction motor (IM), the inductance frequency characteristic, which is determined through measurement [1], [2] or derived from an electromagnetic field analysis carried out using analytical [3] or numerical methods [4], can be considered as motor spectral transmittance of some kind. Therefore an IM operation analysis, realized with the use of a mathematical model based on that characteristic, can be carried out at varying supply voltage parameters as well as at fastchanging electromechanical transients.…”