RAPID ESTIMATION OF INDUCTION MACHINE STATOR CORE LOSSES

This thesis presents a technique for the rapid estimation of induction machine stator core losses using a series of magneto-static finite element analyzes. The methodology is based on partially uniting two previously developed techniques. The first technique allows for the rapid estimation of steady state three phase induction machine properties under field oriented conditions using an iterative magneto-static finite element analysis approach where sinusoidally distributed currents are imposed on the rotor. The second technique utilized was originally developed to characterize the steady state time domain behavior of a three phase synchronous machine using a series of magneto-static finite element simulations with the rotor through one phase belt. In the induction machine analysis application, the rotor is rotated through one phase belt with sinusoidally distributed rotor currents imposed and adjusted to maintain field oriented condition at each rotor position. Stator flux densities are sampled at each rotor position. Exploiting the magnet symmetries, the radial and tangential flux density waveforms in the stator tooth tip, stator tooth, stator tooth yoke and stator yoke regions are reconstructed for one electrical cycle using a minimum number of rotor positions per simulation steps. From the reconstructed stator flux density waveforms, the stator core losses can be estimated using a number of loss models. In this thesis what is known as the CAL2 method is utilized to estimate the loss in each stator region. The rapid estimation of induction machine stator core losses was implemented in MATLAB to script the behavior of FEMM, an open source finite element analysis program. To enable the technique to be used for a wide range of induction machine geometries and make possible future population based design optimization, a flexible parametric geometry was created. To verify the accuracy of the proposed rapid estimation technique, a comparison was carried out on a 2 HP, 3-phase, 4 pole, 60 Hz induction machine with 36 stator slots and 28 rotor slots, between the proposed technique and a transient element analysis carried out in JMAG, a commercial finite element package, for aveerage torque, stator flux densities and total stator core losses.M.S. in Electrical Engineering, May 201