This paper presents the findings of a finite element analysis (FEA) investigation into the effect of rotor/stator misalignment on motor performance in a single rotor, dual stator, axial flux electric motor (AFM). Results obtained from the FEA are in good agreement with experimental measurements giving confidence in the use of the model. The results are useful to machine designers who wish to determine the sensitivity of rotor/stator misalignment, due to assembly errors or tolerance stack on machine performance. Axial offset of the rotor in the air gap is found to cause unbalanced axial forces on the rotor of up to 1400 N. The difference in iron loss between stators increased by 17 and 40% at high speed under open- and short-circuit conditions, respectively. Conversely, angular offset between the two stators was found to have little impact on unbalanced rotor forces and iron loss but a relatively large impact on recirculating currents within the machine which lead to uneven heating of the two stators. For an angular offset of 10 elec. deg. a recirculating current of 93 angstrom was found for a phase current of 175 angstrom. Torque ripple was found to decrease from 8 to 6%.

The design of a ferrite magnet generator with trapezoidal shaped permanent magnets and coils for a wind turbine is studied. Based on the 3-D finite element analysis (FEA), the electromagnetic performances of the two generator prototypes and a simple design modification for one of the axial-flux generator prototypes are analyzed. The best generator is chosen from a range of designs, where the goal is to increase the voltage generated by the 8/8 pole and a single-phase slotless machine. Experimental results from a small size prototype machine validate the 3-D FEA models presented, and hence give confidence in their use for design.

This paper presents the findings of an investigation into the effect of rotor/stator misalignment on motor performance and unbalanced magnetic force in a single rotor, dual stator, axialflux electric motor (AFM). The results are useful to machine designers who wish to determine the sensitivity of rotor/stator misalignment, due to assembly errors or tolerance stack, on machine performance. Axial offset of the rotor in the air-gap is found to cause unbalanced axial forces on the rotor of up to 1400Nm, but have little impact on other machine parameters, such as the torque constant. Conversely, angular offset between the two stators was found to have a little impact on unbalanced rotor forces but a relatively large impact on recirculating currents within the machine which lead to uneven heating of the two stators. For an angular offset of 10 elec. deg. a recirculating current of 93A was found for a phase current of 175A. Torque ripple was found to decrease from 8% to 6%. A combination of 3-D finite element analysis (FEA), and experimental measurements have been used to evaluate the performance of the AFM.

A radial high-speed permanent magnet (PM) machine with concentrated windings (operating frequency up to 800Hz) is selected for automotive application based on hybrid variants. This paper presents selected methods for magnet eddy-current loss reduction by rotor and stator modifications. The first approach to rotor modification regards magnet segmentation in circumferential and axial directions. The second approach is based on changes in tooth-tips shape. The best variants of tooth-tip shapes are determined for further investigation, and adapted with rotor having magnet segmentation. The machine with segmented magnet leads to magnet loss reduction by 81%. Further loss reduction by 45% can be realized with the proposed tooth-tip shape. Furthermore, the most important machine parameters are investigated. The 2-D and 3-D finite element analysis (FEA) is used for electromagnetic analysis. An experimental approach based on a partially wound stator is employed to verify the 3-D FEA. Streszczenie: Celem pracy jest zaprezentowanie wybranych technik redukcji prądȯw wirowych w magnesach w wysokoobrotowym (czestotliwośc zasilania do 800Hz) silniku synchronicznym z magnesami trwalymi, przeznaczonym do aplikacji w ciezkich pojazdach z napedem elektrycznym. W pierwszym podejściu zastosowano segmentacje magnesow w kierunku osiowym i radialnym (redukcja prądow wirowych indukowanych w magnesach do 80%). W drugiej metodzie zbadano ksztalt profilu nabiegunnikow stojana (obnizenie strat mocy w magnesach do 45%). Finalnym celem pracy bedzie wybranie najlepszych wariantow nabiegunnika stojana i zaadoptowanie ich do silnika z segmentacją magnesow, co powinno znacznie poprawic sprawnośc silnika. Dla tych rozwiązan zbadano najwazniejsze parametry silnika. Obliczenia numeryczne przeprowadzono na modelach polowych 2-D i 3-D bazujących na metodzie elementow skonczonych.

The design and development of an axial-flux ferrite magnet slotless generator for use in a small-scale wind turbine is described. The 4/4-pole single-phase machine is designed for simplicity and ease of manufacture and it consists of one slotless stator disc. The generator produces approx. 12 W at 1000 rpm with electrical efficiency of up to 46%. Because the efficiency of the machine is important, the power curve characteristics and voltage produced by the generator are investigated. The presented generator should generate sufficient output DC voltage to charge 4 to 5 batteries of 12 volt each. Finally, the finite element (FE) results are compared with measurements on a prototype. The calculated values coincide to a strong degree with the experimental results.

This paper presents three-and two-dimensional finite element analyses (2D, 3D FEA) of the proximity losses in brushless AC permanent magnet motor with concentrated windings operating at high speed. The proximity effect only occurs if the examined conductor is penetrated by an external magnetic field, which is caused by adjacent conductor currents. To reduce the proximity effect several alternative winding layouts including rectangular wires are used. The calculated results of the eddy current losses within end-winding regions are significant and must be considered in the design of stator windings. 3D calculations are compared with 2D ones to show the behaviour of the eddy-current into the conductors and also compared with respect to the power loss and AC resistance. The calculations are in a good agreement with measurements on a prototype high-speed motor.

W artykule przedstawiono analiz ę wybranych parametrów całkowych generatora o strumi eniu osiowym, którego głównym zastosowaniem b ędzie praca w małej elektrowni wiatrowej. Celem pracy było osiągnięcie żądanej wartości napięcia rotacji wystarczaj ącej do ładowania baterii akumulatorów. W celu zrealizowania tego zadania, zbudowano trójwy miarowy model polowy 3-fazowego bez żłobkowego generatora bazuj ący na metodzie elementów sko ńczonych (MES). Na bazie modelu polowoobwodowego wyznaczono charakterystyki wyj ściowe generatora i jego sprawno ść.

W artykule przedstawiono analize wybranych parametrow calkowych generatora z podwojnym wirnikiem o strumieniu osiowym przeznaczonego do zastosowania w malej elektrowni wiatrowej. Celem pracy bylo osiągniecie wymaganej wartości napiecia rotacji wystarczającej do ladowania baterii akumulatorow. W celu zrealizowania tego problemu zbudowano trojfazowy model polowy oparty na metodzie elementow skonczonych (MES). Na bazie modelu polowo-obwodowego wyznaczono przebiegi czasowe, charakterystyki wyjściowe generatora oraz jego sprawnośc.