Development of Correlations for Windage Power Losses Modeling in an Axial Flux Permanent Magnet Synchronous Machine with Geometrical Features of the Magnets

Abstract

Abstract:In this paper, a set of correlations for the windage power losses in a 4 kW axial flux permanent magnet synchronous machine (AFPMSM) is presented. In order to have an efficient machine, it is necessary to optimize the total electromagnetic and mechanical losses. Therefore, fast equations are needed to estimate the windage power losses of the machine. The geometry consists of an open rotor-stator with sixteen magnets at the periphery of the rotor with an annular opening in the entire disk. Air can flow in a channel being formed between the magnets and in a small gap region between the magnets and the stator surface. To construct the correlations, computational fluid dynamics (CFD) simulations through the frozen rotor (FR) method are performed at the practical ranges of the geometrical parameters, namely the gap size distance, the rotational speed of the rotor, the magnet thickness and the magnet angle. Thereafter, two categories of formulations are defined to make the windage losses dimensionless based on whether the losses are mainly due to the viscous forces or the pressure forces. At the end, the correlations can be achieved via curve fittings from the numerical data. The results reveal that the pressure forces are responsible for the windage losses for the side surfaces in the air-channel, whereas for the surfaces facing the stator surface in the gap, the viscous forces mainly contribute to the windage losses. Additionally, the results of the parametric study demonstrate that the overall windage losses in the machine escalate with an increase in either the rotational Reynolds number or the magnet thickness ratio. By contrast, the windage losses decrease once the magnet angle ratio enlarges. Moreover, it can be concluded that the proposed correlations are very useful tools in the design and optimizations of this type of electrical machine.

A 3D Dynamic Lumped Parameter Thermal Network of Air-Cooled YASA Axial Flux Permanent Magnet Synchronous Machine

“…The windings were excited by a fixed DC current to get controlled losses and to eliminate the stator core losses. The mechanical losses are calculated using equations in [24]. The mechanical losses are lumped and injected in the PM node in the rotor LPTN model.…”

“…The aerodynamic forces acting on rotary parts of the machine cause mechanical losses in the surfaces exposed to it. Extensive CFD simulations and curve fittings done in [24] have found accurate and parametrized formulas for the windage losses on every surface. These formulas are used to calculate the mechanical losses.…”

Finite Element Analysis of Laminar Heat Transfer within an Axial-Flux Permanent Magnet Machine

“…Although this research was conducted in the field of oceanography, its application can be extended to geophysics, astrophysics, and turbomachinery. Apart from localized differences, it has been shown that the general flow field in an AFPM machine is similar to a simplified rotor-stator configuration [4][5][6] to which the generic theory of Ref. [3] applies.…”

“…Although it would be favorable to include such three-dimensional features, this is impractical from a computational effort point of view. Based on results reported in the literature, it is expected that the axisymmetric model will result in similar flow and heat transfer structures compared to the three-dimensional case [4,64].…”

Analysis of Standby Power in an Enclosed High-Speed Flywheel Energy Storage System Using the CFD-ANOVA Approach

“…Investigations into windage losses for large gaps and atmospheric air have been the subject of numerous studies [11]. Numerous researchers have started using CFD numerical simulations in conjunction with experiments in recent years [12]- [16]. In a vacuum chamber, Walton et al [10] investigated the windage losses of a rotor supported by gas foil bearings, but they did not consider the fluid field's impact near the journal.…”