Fractional-slot concentrated-winding axial-flux permanent magnet machine with core-wound coils

Abstract

This paper presents the design, finite element analysis (FEA) and experimental verification of a single stator double rotor fractional-slot concentrated-winding (FSCW) axial-flux permanent magnet (AFPM) machine, with core-wound coils. The advantages that are obtained by adopting such coil construction, in terms of shorter end-winding connections, higher fill factor and mechanical robustness of the magnetic structure are highlighted. Machine performances both at no load and at rated load are analyzed through static FEA and a simple index is introduced, in order to compare induced losses in the permanent magnets for various machine configurations. The construction and experimental testing of a full scale prototype is described, in order to confirm the expected performances and to characterize the prototype in terms of losses, cogging torque and main machine parameters. © 2010 IEEE

Design and Construction of Axial-Flux Permanent Magnet Motors for Electric Propulsion Applications—A Review

“…Two 10-kW water-cooled TORUS type AFPM machines with fractional-slot (FS) CW (FSCW) (24-slot/20-pole) and integral-slot (IS) CW (ISCW) (60-slot/20-pole) are designed and prototyped in [23] and [24] respectively, as shown in FIGURE 5. Among all possible values to form FSCW, the slot number per pole per phase (SPP) has been selected as 2/5 in [23] because of the high fundamental winding factor (0.966) and inherently low cogging torque. The end-turn length of the core-wound and tooth-wound coil configurations is compared based on the average end-turn model of the proposed FSCW TORUS machine.…”

“…Stator-slot and rotor-pole numbers are generally selected according to the power rating and motor size before parametric design and optimization. Fractional slots SPP is preferred for a high fundamental winding factor and inherently low cogging torque [23]. Even numbers of both slots and poles are required for a symmetrical disposition of stator coils and rotor poles to avoid unbalanced magnetic force [31].…”

“…Ref. [23] evaluates the PM losses of an AFPM machine by a simple loss index and FEA at rated speed (800 rpm). The evaluation based on the loss index shows that the PM losses for the semi-closed slot with wedges are about 10% of the losses for the open-slot geometry.…”

Research on a 20-Slot/22-Pole Five-Phase Fault-Tolerant PMSM Used for Four-Wheel-Drive Electric Vehicles

“…With such windings the concentrated coils are wound either on adjacent or alternate teeth, which reduces the end winding length. Furthermore, a significant reduction of the copper loss is achieved, and the machine efficiency is improved [8][9][10]. Compared with traditional distributed windings, FSCW have low mutual inductances between phases, which meet the magnetic isolation demands of phase windings for multiphase fault-tolerant PMSM [11][12][13][14].…”

Design and prototyping of an optimised axial‐flux permanent‐magnet synchronous machine

“…However, the external‐rotor arrangement is considered especially advantageous where the space is limited, mechanical robustness is required and torque‐to‐volume ratio is crucial [15]. The double‐sided slotted TORUS AFPM motors are the most frequently applied among the other configurations, as they are mechanically stronger and have higher power density than the other configurations [16]. So, the slotted TORUS AFPM motor is used here for modelling and simulation.…”