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This article presents an accurate analytical model (AM) for synchronous reluctance machine (SynRM) that incorporates the effect of stator slots on the air gap flux density and torque waveforms. From the formulation of magnetic potential in the air gap for both the stator and rotor, the flux density is obtained, considering the first harmonic of the flux density and the electric loading, the average torque is calculated using the Lorentz’s force. The ripple torque is obtained from the energy stored in magnetic circuit. The method is developed for a rotor with one flux barrier per pole and then extended to a larger number of barriers. To validate the results obtained by the AM proposed finite element analysis have been carried out. Several comparisons have been derived considering different rotor positions as well as different harmonic orders, and the pros and cons of the method are highlighted. The model performs fast and can predict results with high accuracy, and can be adopted to speed up the preliminary design and optimizations of this type of motors, with respect to finite element. In addition, from the analytical expressions it is possible to obtain all the correlations between electrical, magnetic, and geometrical characteristics of the machine, with the advantage of enabling a faster machine design. [ABSTRACT FROM AUTHOR]

This paper deals with a comparative study between reluctance (REL), permanent magnet assisted reluctance (PMAREL), and surface mounted permanent magnet (PM) synchronous machines with rotor eccentricity. Static, dynamic, and combined eccentricity cases are considered. For the sake of generality, this comparison is carried out at different levels of air-gap flux density, as different current angles, different PM materials, and different number of magnetic poles. Additionally, different stator windings arrangements, i.e, distributed and fractional slot concentrated windings are taken into account. Besides, different rotor geometries of REL and PMAREL machines are included. As a case of study, 36-slot machine is analyzed, considering three flux barriers per pole; however, the study can be applied to any machine geometry. Due to the structural criticality of the rotor iron ribs of the REL machines, the impact of the eccentricity on the mechanical stress acting on those ribs and the deformation of the rotor is studied. [ABSTRACT FROM AUTHOR]

Synchronous reluctance machine has high flux density fluctuations in the iron due to the high harmonics results from the rotor anisotropy. Thus, an accurate computation of the iron losses is of paramount importance, especially during the design stage. In this paper, a nonlinear analytical model considering the magnetic iron saturation and the slotting effect is proposed. The model estimates accurately the iron losses at a wide range of operating speed. In addition, the accuracy of the nonlinear model when the machine is highly saturated, i.e., when it works along the maximum torque per ampere (MTPA) trajectory, is presented and verified. The model presented is general and can be applied to other configurations. A 36-slot four-pole machine, with three flux-barriers per pole is considered as a case study. Finite element analysis is used to validate the results achieved by means of the nonlinear analytical model. Furthermore, an experimental setup is built to validate the simulation results. [ABSTRACT FROM AUTHOR]

The synchronous reluctance motor works under heavy saturation. This paper presents a nonlinear analytical model of the reluctance machine, which is used to derive both average and torque harmonics as a function of the rotor geometry. Maps showing the torque harmonics as a function of the rotor barrier angles are derived. These maps are useful tools for the machine designer to get a proper rotor geometry. The torque maps are compared with those obtained from both linear analytical and finite element models. The maps computed analytically show good agreement with those derived by means of finite element analysis, and they are obtained in a much smaller computing time. [ABSTRACT FROM AUTHOR]

This paper deals with an analytical model of reluctance synchronous motor, able to consider both stator slotting effect and magnetic saturation in the stator and rotor iron paths. It joints the field distribution at the air gap to a lumped-parameter magnetic network. Local saturation factors are defined so as to adjust the flux-density distribution. The analytical approach exhibits great potentiality, since it is a formulation based on an harmonic study, and it is easily adaptable to any motor geometries. As an example, 36-slot 4-pole machine is analyzed, considering three flux barriers per pole. Finite element analysis confirms the results achieved by means of the analytical model. [ABSTRACT FROM PUBLISHER]

This paper deals with an improved analytical model of synchronous reluctance (REL) machine considering rotor eccentricity. This model considers the magnetic saturation in the iron parts of both the stator and the rotor. This saturation results from the actual B–H characteristic of the iron. In addition, the slotting effect is considered in the analytical model. The unbalanced magnetic force (UMF) on the rotor is accurately estimated. Furthermore, the impact on the estimated UMF due to the slotting effect and the magnetic saturation is studied. Both static and dynamic eccentricity cases are considered. As an example, a four-pole 36-slot REL motor with three flux-barriers per rotor pole is considered. Experimental measurements confirm the results achieved by means of both finite-element analysis and the improved analytical model. [ABSTRACT FROM AUTHOR]

In the permanent magnet (PM)-assisted reluctance motors, low-energy PM, such as Ferrite PM, is used to get a cheap rotor. As far as the design choices are concerned, the PM width has to be selected so as to achieve the desired air-gap flux density at no-load condition and the PM thickness has to be selected to avoid the demagnetization of the PM under full-load conditions. This paper presents a practical analytical approach to compute PM width and thickness according to a given air-gap flux density and stress on the PM itself. Two approaches based on a complete model and a simplified model are considered and compared. As an example, a 36-slot 4-pole machine is designed. Finite element analysis confirms the results achieved by means of both analytical analyses. [ABSTRACT FROM PUBLISHER]

In this paper, a coupled experimental–mathematical inverse problem based methodology for the detection of interturn faults in an asynchronous induction machine is presented. The fault detection is accomplished by interpreting well-defined measurements into the machine mathematical model. First, the studied machine is modeled by means of a dynamic state-space model in the $abc$ reference frame. This model simulates the machine behavior under healthy and faulty cases in both transient and steady-state conditions. The signature of the interturn fault is captured using the magnetic pendulous oscillation technique. The proposed inverse problem is validated numerically and experimentally. The results show the robustness of the proposed scheme against the measurement noise. [ABSTRACT FROM AUTHOR]

Referring to the analysis of the impact of the eccentricity on a synchronous reluctance motor presented in the companion paper (Part I), a comparison is carried out between rotors with symmetric and asymmetric flux-barriers. As an example, a four-pole machine with one or two flux-barriers per pole is used. In addition, the analysis is also applied to motors with fractional-slot coil windings. Both single- and double-layer windings are considered. As an example, a six-slot four-pole machine with concentrated windings and 36-slot four-pole machine with distributed windings are compared. The analytical model which is proposed in Part I is used to predict the machine performance. A finite-element analysis confirms the results achieved by means of the analytical model. [ABSTRACT FROM AUTHOR]

In recent years, there is a growing interest for synchronous reluctance machines. This is due to their high torque density, flux-weakening operation capability, and high fault-tolerance capability. This paper deals with the analysis of a synchronous reluctance machine when eccentricity occurs. Both static and dynamic eccentricity are considered. An analytical model to predict the machine performance is described. As an example, a four-pole reluctance machine is analyzed, considering single, as well as multi flux-barriers per pole. The finite-element analysis confirms the results achieved by means of the proposed analytical model. [ABSTRACT FROM AUTHOR]