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This paper investigates the influence of magnet imperfections on the torque pulsation of permanent magnet machines having different pole/slot combinations (2p/Ns), including fractional-slot as well as integer-slot topologies. The magnet imperfections result in changing in the cogging period, which in turn might reduce the effectiveness of skewing, and also introduce new harmonic orders that could...
This paper investigates the influence of magnetic saturation on the rotor bar current waveform and performance characteristics of a squirrel-cage Induction Machine (IM). The levels of iron saturation in different parts, including stator and rotor back iron, tooth body and tooth tips etc., are examined and their influences are investigated, while the dominant part which causes the non-sinusoidal rotor...
The rotor design has a large effect on the performance of Permanent-Magnet-Assisted Synchronous Reluctance Motors (PMaSynRMs). An optimized rotor geometry is necessary in order to obtain higher motor torque with minimum torque ripple. This paper investigates the influence of the flux-barrier design which is the most important rotor geometry parameter regarding the torque and torque ripple of PMaSynRMs...
This paper presents a time-efficient transient numerical method for three-dimensional analysis of rotor losses in a three-phase 2-pole high-speed permanent-magnet synchronous machine. The motor has axially stacked ring shaped permanent magnets (PM). The influence of shaft material properties on rotor harmonic losses and loss distribution between the rotor shaft and magnets is investigated in the frequency...
Saturation effects in the magnetic active iron areas lead to odd air gap harmonics in electrical machines. Whereas the influence of tooth saturation is analytical described by a flattening factor, the impact of yoke saturation is neglected by this factor so far. Finite element analyses are done in order to receive the air gap harmonics. The simulations are performed with high permeability material...
Rotor bar current of an induction machine (IM) designed by using the same stator outer diameter, stack length, air-gap length, output power and rated speed as the Toyota Prius 2010 interior permanent magnet machine is investigated. It is observed that in some cases the rotor bar current waveform can be non-sinusoidal even if the stator windings are fed with a sinusoidal source. The conditions for...
This paper focuses on the fast modelling of Switched Reluctance Machines (SRMs) taking into account the magnetic coupling of the phases through a combined Magnetic-Equivalent-Circuit (MEC) and Finite-Element (FE) approach. The airgap flux and the local saturation of partially overlapping pole corners is considered with a reduced FE model in a preprocessing step. With this combined MEC-FE model, the...
In this paper a novel method for modeling and simulation of a slot harmonics estimation model is presented. This model calculates only the harmonics due to the slotting and therefore can be easily added to an existing model of a wound rotor induction machine. The approach presented in this paper is also valid for developing a slot harmonics estimation model of a doubly-fed induction machine since...
Transverse flux machines are electrical machines offering a high torque density by increasing the number of pole pairs by decoupling the electric from the magnetic design. The field of application includes low speed direct drives if challenges like the complex design and high torque ripple are solved. For the development of sophisticated control algorithms, accurate machine models are required. This...
This paper reports on the modelling of a direct-driven brushless DC permanent-magnet (BLDCPM) generator to be used in micro-wind turbine applications for long-term wind-speed profiles. Three models are investigated and confronted in precision and computation time. For power loss calculation of BLDCPM generator operating under large time-scale wind-speed fluctuations, an original barycenter method...
Wind power turbines have shown a significant increase in the energy production capabilities in recent years. For better reliability and higher efficiency, the direct drive permanent magnet (PM) generators become more desirable, particularly for off-shore wind turbines. This results in generators with large diameter and high pole pair number. To investigate the influence of manufacturing tolerances...
This paper describes a novel axial flux permanent magnet (AFPM) biased eddy current brake (ECB). Structure, principles of operation and benefits of the proposed AFPM-ECB compared to conventional ECBs are presented. A non-linear magnetic equivalent circuit based design model is generated for the proposed AFPM-ECB. Detailed 3D finite element models (FEM) are created to see more accurate breaking torque...
Standard modelling approaches for a triple three-phase (i.e. nine-phase) machine include vector space decomposition (VSD) and triple d-q modelling procedure. Each is characterised with certain benefits and shortcomings. This paper introduces a novel transformation, applicable to multiple three-phase winding machines in general, especially aimed at facilitating the power (current) sharing between the...
The paper is aimed at the analysis of the influence of the third spatial harmonic of the MMF on the stator currents and the torque of a five-phase synchronous machine with surface-mounted permanent magnets. The analysis is carried out on the basis of the method of space vectors and symmetrical components of instantaneous values of currents and voltages. The mathematical description of the machine...
This paper presents a non-linear analytical model of a multi-V-shape Interior Permanent Magnet (IPM) motor with non-overlapping concentrated winding. The model relies on Maxwell equations to compute the flux density in the different parts of the motor. This article proposes a saturated analytical model of the stator and the rotor. The analytical model is used to calculate the average torque, the power...
Steep wavefront voltages of pulse width modulated (PWM) inverters cause common-mode (CM) bearing currents due to the capacitive coupling between stator windings and rotor core. The CM bearing currents represent a current unbalance of the three-phase winding system producing a high-frequency (HF) magnetic flux around the motor shaft that induces the so-called circulating bearing currents. The circulating...
Conformai mapping is a widespread mathematical technique to approach the electromagnetic study of electric machines. In its practical application, however, it is relatively easy to incur in errors which make results unreliable. In this paper, some fundamental but possibly deceitful facts in conformal mapping application are described, focusing in particular on: energy conservation in magnetostatic...
Cogging torque produces negative effects in Permanent Magnet Synchronous Machines (PMSMs) such as vibrations, noise and position control inaccuracy. Its impact can be worse due to magnetic saturation when the machine is loaded, increasing its amplitude and causing the magnet or stator slot skew to be ineffective. This paper deals with the study of these phenomena combining a Permeance Network Model...
In this paper, the investigation is focused on the influence of tooth-tip local magnetic saturation on the on-load performances, such as on-load flux linkages, inductances, onload back EMFs, on-load cogging torques, torque ripples, iron and PM eddy current losses, in a closed-slot fractional slot surface-mount machine. It is found that due to influence of local magnetic saturation in the tooth-tips,...
This paper gives the detailed derivation of a parameterized cage induction machine dynamic model in the natural frame of reference. The model is suitable for the analysis of the impact of a different number of rotor bars on machine transients as well as steady state performances. After the initial induction machine design process, for a predetermined number of stator slots and rotor bars, the parameterized...
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