Fig 4 - uploaded by Fabio Crescimbini
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Views of a rotor disc. (a) Air gap facing disc surface with skewed magnets. (b) Mechanism used for adjusting the magnet skewing.
Source publication
The axial-flux permanent-magnet machine (AFPM) topology is suited for direct-drive applications and, due to their enhanced flux-weakening capability, AFPMs having slotted windings are the most promising candidates for use in wheel-motor drives. In consideration of this, this paper deals with an experimental study devoted to investigate a number of...
Contexts in source publication
Context 1
... shown in Fig. 3(b), in each of the machine rotor discs the magnet slabs are mounted on supporting circular-shaped iron plates which can be rotated in either clockwise or counterclock- wise direction with respect their own axes in order to achieve adjustable skewing of the magnets as shown in Fig. 4(a). This goal is accomplished at once for all magnets through a suitable mechanism placed on the back side of each rotor disc and in- cluding as many connecting rods as the machine poles, as shown in Fig. ...
Context 2
... clockwise or counterclock- wise direction with respect their own axes in order to achieve adjustable skewing of the magnets as shown in Fig. 4(a). This goal is accomplished at once for all magnets through a suitable mechanism placed on the back side of each rotor disc and in- cluding as many connecting rods as the machine poles, as shown in Fig. ...
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Abstract -- In this paper an iron core axial flux permanent magnet machine with a non-overlap concentrated
winding is presented for in-wheel traction hub motor drives. The design and optimization is carried out for
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Citations
... Therefore, design-based approaches are more effective than control-based ones. Skewing of magnets or stator, slot opening variation, the addition of dummy slots, step skewing, unequal placement of rotor magnets, fractional of slots per pole, and segmented stator laminations are some techniques to minimize CT [11][12][13][14][15]. Skewing is widely adopted method in the industry [16]. ...
Brushless direct current motors have more attractive features, making them a promising solution for electric vehicle applications. A 1 kW, 510 rpm, 24-slots and 8-pole inner runner type surface permanent magnet mounted radial flux brushless DC motor with seven different permanent magnet pole shape rotor is investigated. Motors with different permanent magnet shape rotors were designed, and finite element modelling and simulation were carried out. For performance comparison, the initial design with a radial-type pole shape was regarded as a reference design. Cogging torque is detrimental to the overall performance of the motor, typically in low-speed applications like electric vehicles. The primary aim of this paper is to reduce the cogging torque & study its effect on the overall performance of the motor and minimize torque ripples with reduced permanent magnet requirements. The proposed designs are analyzed in terms of cogging torque, flux density, torque, efficiency, flux linkage and back-EMF. The comparative analysis shows that the motor with bump-shaped permanent magnet rotor poles has betterperformance than the others.
... This structure is mainly preferred in applications where a lower cogging torque and torque ripple is required. [4] In double stator -single rotor axial flux motors, the rotor is located between two stators and the main flux flows either circular along the rotor disc or axial through the rotor disc. The double stator -single rotor design can improve the effect of flux focusing and drive the flux to flow over dual air gaps and relatively decrease the leakage flux. ...
In this paper a concept study for a lightweight cryogenic hydrogen cooled axial flux motor is presented. The concept is based on a hybrid material design to fulfill the electro-magnetic, thermal, chemical, and mechanical requirements for a high-performance electrical drive train for Urban Air Mobility (UAM) applications. The concept study focuses on the virtual pre-design of the rotor stator combination and the cooling system using composites and ferromagnetic materials. FE and electromagnetic performance simulation results based on trade studies will be presented as well as an outlook for the thermal and chemical material characterization the cooling system operated with cryogenic hydrogen.
... The AFPM motor is thin and proportional to the cubic diameter. Therefore, the AFPM motor can effectively generate torque [21][22][23][24]. The shorter the axial length of the motor for robot joints, the better. ...
The core design elements of the motor for the co-robot joint are miniaturization and high torque. In this paper, a dual rotor axial-flux permanent magnet (DRAFPM) motor is proposed to improve the performance of robot joints. DRAFPM motors have the advantage of reducing iron loss and minimizing volume because they can remove stator yoke. When designing a motor with the same volume, it can be designed to increase the height of the fixed ruler by the thickness of the yoke of the fixed ruler and increase the number of turns. In the case of existing axial-flux permanent magnet (AFPM) motors, the shape of the three-dimensional structure is limited by radial laminating of stator. Therefore, considering the production of 3D printing, the shape of stator shoe is designed. The optimal design problem of DRAFPM motor consists of real and integer design variables. In addition, due to the structural characteristics of DRAFPM motors, 3D finite element analysis (FEA) is required, so it takes a long time to interpret. Therefore, this paper proposes an efficient optimal design process to optimize the remaining real design variables after prioritizing the integer design variables. The proposed optimization process is applied to the DRAFPM motor for robot joints, and the optimal design plan satisfying the design function is derived from various design variables to prove the validity of the optimization process.
... The effect of magnet shape on cogging torque is elaborated in [13]. Effect of skewing and step skewing are given in [14][15][16][17]. The use of alternate magnet pole-arcs is proposed in [18]. ...
... Skewing the permanent magnet, changing the PM Pole arc width, PM Pole arc with different widths, are some effective methods for the rotor side and for stator side they recommended notches in the teeth. Federico Caricchi et al. [4] tried a new design to compare various technical solutions. Such as PVC or Somaloy used in slot wedges, magnet skewing, angular shifting between the rotor discs, and mounting of magnets having distinct widths and arranged with either regularly spaced or in shortened pitch fashion on the discs are some methods. ...
Cogging torque is an unfavorable hindrance in Permanent Magnet Brushless DC (PMBLDC) motor. In medium-low power PMBLDC motors, the surplus oscillations and intolerable noise happen because of the harmonic magnetic forces created by cogging torque. This paper introduces a new approach for the diminution of cogging torque. This method is based on placement irregularities in rotor magnets, and for this a new combination of pole arc and pole pitch was considered. The reference model has a pole pitch of 90° and pole arc of 63°. The new pole pitch is attained by the application of shifting technique on the permanent magnet and for the new pole arc it was resized. An analytical expression using the Virtual Work Method (VWM) Method was derived for locating the pole pitch and pole arc with nominal cogging torque in the PMBLDC motor. The technique is explored using 3D Finite Element Analysis (FEA). The comparison of the simulation and analytical results of cogging torque is accomplished. It is figured out that the cogging torque minimization in the analytical results exhibited acceptable agreement with FEA analysis.
... Studies have shown that multi-objective shape optimization [26] and singleobjective optimization [27] can help to diminish the influence of the cogging torque effect. Numerous studies have been dedicated to experimentally studying reduction of cogging torque effect [28][29][30]. The emphasis on a no-load mode of an axial flux machine [28] has resulted in cogging torque reduction. ...
... Numerous studies have been dedicated to experimentally studying reduction of cogging torque effect [28][29][30]. The emphasis on a no-load mode of an axial flux machine [28] has resulted in cogging torque reduction. Another study tested core losses and their influences on cogging torque [29]. ...
An axial flux permanent magnet single-rotor generator has good potential in various applications that require high efficiency, prolonged service life, as well as low mass and dimensions. However, the effect of cogging torque diminishes generator efficiency and flexibility of functionality. The effect of cogging torque arises because of a small air gap between the stator teeth and the rotor. In this article, we suggest that shifting the opposite teeth of the stator to the optimal angle can reduce the effect of cogging torque. A special axial flux permanent magnet generator is developed to choose the optimal disposition of the permanent magnet and stator teeth in the frame. The impact of the optimal angle on the cogging torque, output power, and generator efficiency is investigated. This analytical study with experimental testing proves that the optimal angle between opposite teeth can significantly decrease cogging torque and improve output power and efficiency. The results show that cogging torque decreases significantly (4–5 times) at an optimal angle of 7.5° as compared with that of other angles, although magnetic flux and output power decline slightly but efficiency increases.
... This paper proposes a design procedure for 48V, in-wheel direct-drive systems for electric vehicles integrating thermal modelling of both motor and inverter, and manufacturing process analysis of the motor to estimate machine cost. With consideration of the limited space for in-wheel application, both axial-and radial-flux machines were introduced in the literature [2,[5][6][7][8][9][10][11]. Fig. 1 summaries several machines with suitable size for in-wheel application, where machine type (radial/axial flux (RF/AF) with surface mounted/ interior PM (SPM/IPM), continuous torque density, and cooling method have been marked. ...
... IPM: interior PM machine. [2,[5][6][7][8][9][10][11] ...
... Two main measuring methods can be distinguished between: The static and dynamic cogging torque measurements. The static measurement is essentially lever based, where either the reaction torque of the stator is measured [4], [5] or force is applied to the rotor observing the change in the rotor position [6]- [8]. The dynamic measurement is usually performed using torque transducers [3], [9]- [14], often with bias torque for a measuringrange extension, which must have sufficient bandwidth and accuracy to capture all cogging harmonics. ...
Accurately measuring the cogging torque, hysteresis torque, and iron losses of permanent magnet (PM) motors is a challenging task. This is especially true for sub-fractional horsepower (SFHP) variants used, e.g., in auxiliary drives for automotive fan and pump applications. Their cogging torque and hysteresis torque peak values are often in the sub-milli- Newton meter range, causing conventional measuring methods and devices to fail as especially friction impedes the measurement significantly. Moreover, their iron losses are hard to determine and usually merely estimated in the literature. This paper presents an unconventional rheometer-based method to determine both 1) the cogging torque and hysteresis torque of SFHP PM motors and 2) their iron losses by evaluating the observed offset torque. Two SFHP outer-rotor PM motor topologies for fan applications are analyzed, i.e., a claw-pole motor and a salient-pole motor. The results show that, with the proposed setup, settings, and evaluation, a rheometer can successfully be used to determine cogging torque and hysteresis torque waveforms in the sub-milli-Newton meter range and the iron losses of SFHP motors, both with excellent accuracy.
... AF-PMSM topologies are classified among themselves according to core shape, slot structure, coil structure and the positioning of the magnets. AF-PMSM topologies have advantages and disadvantages when compared with other topologies [11][12][13][14][15][16]. In addition, studies have also been carried out on various parameters such as back-emf induced in AFSM [16][17][18], cogging torque [19,20] and torque ripple [21]. ...
This study presents design and performance analyses for a new line start axial flux permanent magnet synchronous motors (AF‐PMSMs). The innovative part of this study is that AF‐PMSM can start directly from the line and operate with high efficiency and power factor after synchronisation. Prototype manufacturing was carried out after completing the analytical and electromagnetic designs for the targeted motor. The synchronisation capacity, power capacity, power–speed characteristic, power‐efficiency relationship along with the total harmonic distortion and back‐emf waveform of the induced voltage have been examined for the prototype motor. Simulation studies have been verified experimentally. The results obtained were compared with an induction motor with the same power. It was observed as a result of the work carried out and a line start AF‐PMSM is obtained that is 4–10% more efficient in comparison with an induction motor having the same power.
... In [3], AFPM machines with different magnet shapes have been investigated to achieve an almost sinusoidal air-gap flux density distribution. A comprehensive review is illustrated in Table 1 [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Type of structure Characteristics Single-stator single-rotor Compact construction, high torque Double-stator single-rotor Ratio of power to high inertia Single-stator double-rotor Possibility to delete groove and stator iron Multistator multirotor Power density, high speed and power ...
Recently, much attention has been given to axial flux permanent magnet generators due to some advantages such as high efficiency, high power density, and higher torque compared to radial flux generators. In addition, increased number of poles makes them appropriate for low-speed applications such as wind power generators. In this study, an axial flux permanent magnet synchronous generator with unique features such as high power density is designed for small-scale wind turbines. The structure of generator includes a rotor and a stator. The generator is designed and then analyzed by Flux 11.2 software. The analysis includes the effects of air gap distance change with considering wind speed variations. Sinusoidal waveform of induction voltage with the acceptable harmonic characteristics confirms the optimized design of the generator.
