The cage losses in induction machines due to spatial or time harmonics in the air-gap field are a crucial parameter for a precise estimation of the machine efficiency. Using finite element, the common approach to consider the overall cage losses, by performing complete time-domain analyses. Alternatively, a rough estimation is achieved introducing equivalent parameters in the circuital model. In this paper, a methodology for cage losses computation due to air-gap spatial field harmonics is described. The proposed finite element procedure is faster than the time-domain analysis, since it is based on magneto-static and linear time-harmonic simulations to carefully consider the iron saturation and compute the induced currents in a specific working point. In the paper, a detailed procedure description and comparison with respect the time-domain approach is reported.

In this article, a novel procedure for the induction motor analysis is presented, avoiding the time-domain finite element problem formulation. The proposed technique closely links the mathematical model of the motor to the finite element simulations, concerning magneto-static and time-harmonic analyses. The target of the method is to include, in a rapid machine computation, also the effect of the slip frequency on the bars' current distribution and the induced currents in the cage due to the stator belt harmonics. The reported analysis example concerns the stand still operation of a double cage induction machine, where the rotor frequency is the grid frequency and the high stator current intensifies the role of the belt harmonics. A further application example concerns a flux weakening working point of a single cage induction motor in a variable speed drive. The aim of this work is to propose procedures to get a fast prediction of the induction motor performance, including also the principal parasitic effects, e.g. the rotor bars' skin effect and the stator belt harmonics, without using any time-domain analysis.

This paper deals with a complete finite-element analysis procedure for squirrel cage induction motors, including the presence of skewing and the iron losses evaluation. The machine is analyzed performing only magneto-static finite element analyses. Saturation phenomena are carefully considered in any operating condition, avoiding long time-stepping analyses. The synergy between analytical and finite element model leads to a rapid and precise estimation of the rotor induced current, saving computational time. Furthermore, the procedure proposed in this paper allows the motor performance to be directly derived, without the preliminary knowledge of the machine equivalent circuit. In order to complete the analysis, skewing effect is included, using the 2-D multi-slice technique, based on static simulations. Experimental tests are carried out and reported in order to verify analysis results.

This paper describes a fast approach for synchronous reluctance machine flux linkage mapping considering the cross-saturation effects. The rapid prediction of the flux maps λ_d ( i_d,i_q ) and λ_q ( i_d,i_q ) only requires the data (from finite element analysis or measurements) along the boundaries of the range to be mapped. To this purpose, two proper functions are defined to predict the effect of cross saturation based on the coenergy variation. The two analytical functions can be computed directly from the data acquired on the boundaries of the ( i_d,i_q ) current plane depending respectively on i_d and on i_q values. The method is applied to predict the flux linkage maps of a synchronous reluctance machine. The results from the semi-analytical method are compared to the full finite element analysis approach and with measurements. In the last part of the paper, different saturation models, based on a limited set of simulations, are compared, showing the new proposed method's potential, against other simplified approaches for a fast mapping.

The focus of this work is on the experimental measurement and the proper finite-element prediction of stator and rotor flux linkages for induction machines. The purpose is to characterize the stator and rotor flux linkages adopting a rotor field oriented reference frame. The proper basic set of equations is inspired by the direct field oriented control approach, in order to indirectly derive the rotor flux linkage from the measurement of the stator flux. The proposed method requires a small set of preliminarily known parameters, such as the stator resistance and the overall leakage inductance. Moreover, the only measured quantities are voltages and currents, from which the flux linkages are derived. The adopted strategy also allows to estimate electromagnetic torque and rotor resistance, using the rotor field oriented model equations. A complete finite-element validation is reported for comparison.

The paper aims to present a method for forecasting flux linkages and torque maps using only the measured dataset at the boundaries. The experimental mapping technique integrates a sequence of tests to measure self-axis saturation characteristics, coupled with a magnetic model based on co-energy principles. This approach, in addition to being fast because requires only a few tests (measurements are solely necessary along the map boundaries), intrinsically addresses cross-saturation effects. The accuracy of the method has been compared with the reference measurements from the constant-speed method applied to a 3kW synchronous reluctance machine. Lastly, a procedure based on the same tests is described useful for accurately estimating position errors introduced by the rotor locking system.