This paper presents a method to estimate the magnetic properties and width of a damaged area which is the result of the carried out punching process. Both a finite-element method (FEM) numerical model and a method for estimating the damaged area width are proposed based on data obtained from the noninvasive measurements as well as on an experimental study of the crystallographic structure. In addition, the authors propose an algorithm, using the FEM numerical model, to identify the equivalent magnetic properties of the material in the damaged area. The results obtained from the FEM model were compared with those obtained by the analytical formula proposed earlier.

During the past 50 years, the aim to reduce the eddy current losses in magnetic cores to a minimum led to the formulation of new materials starting from electrically insulated iron powders, today called Soft Magnetic Composites (SMC). Nowadays, this promising branch of materials is still held back by the mandatory tradeoff between energetic, electrical, magnetic, and mechanical performances. In most cases, the research activity focuses on the deposition of an insulating/binding layer, being one of the critical points in optimizing the final composite. This insulation usually is achieved by either inorganic or organic layer constituents. The main difference is the temperature limit since most inorganic materials typically withstand higher treatment temperatures. As a result, the literature shows many materials and process approaches, each one designed to meet a specific application. The present work summarizes the recent advances in state of the art, analyzing the relationship among material compositions and magnetic and mechanical properties. Each coating shows its own processing sets, which vary from simple mechanical mixing to advanced chemical methods to metallurgical treatments. From state of the art, Aluminum coatings are characterized by higher current losses and low mechanical properties. In contrast, higher mechanical properties are obtained by adopting Silicon coatings. The phosphates coatings show the best-balanced overall properties. Each coating type was thoroughly investigated and then compared with the literature background highlighting. The present paper thus represents a critical overview of the topic that could serve as a starting point for the design and development of new and high-performing coating solutions for SMCs. However, global research activity continuously refines the recipes, introducing new layer materials. The following steps and advances will determine whetherthese materials breakthrough in the market.

In this paper, the stray load losses due to the air gap spatial harmonics effects on the rotor squirrel cage are considered and a simplified induction motor equivalent circuit able to include them in the machine power balance is reported. In the proposed model, an additional resistance appears in series with the stator impedance. This additional parameter has been defined on the basis of power balance considerations applied to the induction motor classical theory. The complete theoretical analysis together with the guidelines to measure the equivalent circuit parameters are reported in detail. Finally, the proposed approach has been experimentally verified using five total enclosed fan cooled induction motors.

The paper presents a method to determine the deterioration effects due to the punching process on soft magnetic materials used in electrical machines. Furthermore the possibility to recovery the magnetic and energetic original properties by mean of subsequent annealing treatments is reported too. The proposed methodology is based on a full experimental approach. Five toroidal cores, with the same geometrical dimensions, have been assembled overlapping a different number of laminations shaped as concentric rings. The rings have been obtained by means of a punching process: in this way the five cores have consistent differences in terms of punched edge length. The comparison between the magnetic and energetic properties on the five cores has put in evidence in qualitative and quantitative ways the punching process effects. In order to quantify the recovery of the magnetic and magnetic properties of the magnetic material, an annealing process has been applied on five other cores, twins with the first five. In addition, the cores have been tested at several frequencies in the range of 10 Hz to 100 Hz and the separation between eddy current and hysteresis losses has been obtained. The experimental test on the annealed cores has highlighted a heavy recovery of the hysteresis loss increase due to the punch process and a reduction of the global specific iron losses. The annealing process allows recovery of the specific losses with a reduction of about 40%, due to a hysteresis contribution reduction. On the base of the results obtained on the cores two twin 11 kW induction motor have been assembled. The first one with a standard stator core, the second one with an annealed stator core. The comparison between the iron losses measured on the two motors has shown that a 20% reduction of the motor iron losses can be obtained

This paper aims to tackle the general problem of increasing the performances of small permanent-magnet (PM) machines, through the use of bonded magnets instead of the more diffused ferrite magnets. In particular, the study is developed for a fractional-slot concentrated winding PM machines for automotive applications. Neodymium bonded magnets with different and unconventional resins are realized in the internal laboratories. The rotors with the different magnet technologies are experimentally characterized, and the experimental values are compared with the simulation ones. The obtained results allow to define the possible performance increment. Finally, this paper analyzes the possible improvement of the rotor magnetic circuit for a better exploitation of the bonded magnets, without altering the stator structure and the motor housing.

In this paper, the analysis of some possibilities for increasing the induction motor efficiency using production technological process modifications is reported. This approach is known as the "no tooling cost" (NTC) strategy because it does not require a complete redesign of new laminations with a consistent cost in terms of investments. The paper shows the results obtained by a full experimental approach, using "ad hoc" prototypes. The NTC design modification and the technological processes analyzed in this paper have been done on totally enclosed fan-cooled standard induction motors. Obviously, the original motors have been compared from the energetic point of view with these prototypes. The energetic performance has been measured in accordance with the IEEE Std. 112-96 Method B. In particular, the following modifications, for obtaining an increase in efficiency, have been taken into consideration: rotor with copper bar included in the slot before the aluminum die cast, increase of the core axial length, and annealing of the stator core.