The Experts below are selected from a list of 6297 Experts worldwide ranked by ideXlab platform
Z Q Zhu - One of the best experts on this subject based on the ideXlab platform.
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feasible stator Rotor Pole combinations of variable flux reluctance machines with second harmonic current injection method
IEEE Transactions on Industry Applications, 2020Co-Authors: Liren Huang, Z Q Zhu, Jianghua Feng, Shuying Guo, J X ShiAbstract:The second harmonic current injection method is recently developed to enhance the torque density of variable flux reluctance machines (VFRMs). This article investigates the feasibility and effectiveness of the second harmonic current injection method in VFRMs with different stator/Rotor Pole combinations. By using magnetic gearing effect, it is found that the second harmonic injection method can only be applied to the 6 j /(6 i ± 2) j ( i , j = 0, 1, 2…) stator/Rotor Pole VFRMs for the torque density enhancement. For the other stator/Rotor Pole combinations, the second harmonic current has no contribution in average torque production but only leads to excessive torque ripple. Further, by using global optimization method and finite element analysis, 6/8 stator/Rotor Pole combination is proved to be the optimal stator/Rotor Pole combination for 6-stator-slots VFRMs with the second harmonic current injection method, being able to exceed the maximal torque density of conventional VFRMs by 12% at a fixed copper loss.
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stator Rotor Pole combinations of variable flux reluctance machines with 2nd harmonic current injection method
International Electric Machines and Drives Conference, 2019Co-Authors: Liren Huang, Z Q Zhu, J H Feng, S Y Guo, J X ShiAbstract:The 2nd harmonic current injection method is recently developed to enhance the torque density of the variable flux reluctance machines (VFRMs). This paper investigates the effectiveness of the 2nd harmonic current injection method in VFRMs with different stator/Rotor Pole combinations. By using magnetic gearing effect, it is found that the 2nd harmonic injection method can only be applied to the $6j/(6i\pm 2)j \ (i i=0,1,2\ldots)$ VFRMs for the torque density enhancement. For the other stator/Rotor Pole combinations, the 2nd harmonic current has no contribution in average torque production and only leads to excessive torque ripple. Further, by using global optimization method and finite element analysis (FEA), 6/8 is proved to be the optimal stator/Rotor Pole combination for 6-stator-slots VFRMs with the 2nd harmonic current injection method, being able to exceed the maximal torque density of conventional VFRMs by 12% at a fixed copper loss.
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analysis of open circuit dc winding induced voltage in partitioned stator hybrid excited switched flux machine
International Conference on Ecological Vehicles and Renewable Energies, 2019Co-Authors: X Y Sun, Z Q ZhuAbstract:This paper analyses the DC winding induced voltage in a partitioned-stator hybrid-excited switched-flux permanent magnet (PS-HESFPM) machine under open-circuit operation. The phenomenon and mechanism of the open-circuit DC winding induced voltage are described. Two techniques are proposed and comparatively analyzed by the finite element (FE) method to reduce the open-circuit DC winding induced voltage, i.e., Rotor Pole arc pairing and unevenly distributed Rotor teeth, respectively. FE results show that the peak to peak value of the open-circuit DC winding induced voltage can be reduced by 89.89% and 88.73%, whilst the average on-load electromagnetic torque can be maintained at 97.64% and 97.02%, by using Rotor Pole arc paring and unevenly distributed Rotor teeth, respectively.
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investigation of torque production and torque ripple reduction for six stator seven Rotor Pole variable flux reluctance machines
IEEE Transactions on Industry Applications, 2019Co-Authors: Beomseok Lee, Z Q Zhu, Liren HuangAbstract:This paper investigates the torque production and the torque ripple reduction of a six-stator/seven-Rotor-Pole (6/7) variable flux reluctance machine (VFRM). As a main advantage, the 6/7 VFRM produces higher torque density, but less torque ripple compared with the 6/4 VFRM. The instantaneous torque equation of the 6/7 VFRM is derived by considering the spectra of the winding inductance and current. Based on the derived equation, the average torque is found to be mainly produced by the mutual inductance between the field and armature windings. The even-order harmonics of self-inductance and odd-order harmonics in mutual inductance between the field and armature windings are eliminated due to the opposite polarity connection of the armature coils in each phase. This results in the elimination of the third harmonic torque ripple, while a multiple of the sixth harmonic torque ripple exists. In order to mitigate the sixth harmonic torque ripple, the harmonic current injection method is implemented into the field winding. The field harmonic current is calculated from the analytical torque ripple equation. The performance of the proposed methods is verified by both finite element analysis (FEA) and experiment.
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analysis of stator Rotor Pole combinations in variable flux reluctance machines using magnetic gearing effect
IEEE Transactions on Industry Applications, 2019Co-Authors: Liren Huang, Z Q Zhu, Jianghua Feng, Shuying Guo, J X Shi, W Q ChuAbstract:The torque production of variable flux reluctance machines (VFRMs) is explained by the “magnetic gearing effect” in recent research. Based on this theory, this paper concludes the general principles for feasible stator/Rotor Pole selection and corresponding winding configuration for VFRMs. The influence of stator/Rotor Pole combination on torque performance is comprehensively investigated not only in terms of average torque and torque ripple, but also in terms of each single torque component. It is found that the synchronous torque is proportional to the fundamental Rotor radial permeance component and has the dominant contribution in average torque for all the VFRMs. The stator slot number and Rotor Pole number should be close to each other to achieve the highest output torque. Meanwhile, the 6-stator-slot/(6 i ± 2)-Rotor-Pole (6s/(6 i ± 2)r) and their multiples are large torque ripple origins for VFRMs due to the large reluctance torque ripple. Also, it is proved that a lower stator slot number is preferable choice to obtain higher torque/copper loss ratio, whereas a higher stator slot number is more suitable for large machine scale scenario. Finally, the analyses and conclusions are verified by finite element analysis on the 6-, 12-, 18-, and 24-stator-slot VFRMs and by experimental tests on a 6s/7r and 6s/8r VFRMs.
J T Chen - One of the best experts on this subject based on the ideXlab platform.
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influence of slot opening on optimal stator and Rotor Pole combination and electromagnetic performance of switched flux pm brushless ac machines
IEEE Transactions on Industry Applications, 2011Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:The significant influence of slot opening on the optimal stator and Rotor Pole combination and on the electromagnetic performance of the switched-flux permanent magnet (SFPM) machine is observed and investigated in this paper. A new SFPM brushless machine with remarkable slot opening relative to the magnet thickness is developed to reduce the magnet usage and to increase the slot area. Its stator slot opening is almost several times of that in the conventional SFPM machine, but its magnet usage is only half. However, the new machine exhibits ~ 40% larger back EMF and electromagnetic torque than those of the conventional machine, while its cogging torque and torque ripple are significantly lower.
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a novel hybrid excited switched flux brushless ac machine for ev hev applications
IEEE Transactions on Vehicular Technology, 2011Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:A novel E-core hybrid-excited switched-flux permanent-magnet (SFPM) brushless machine is proposed based on an E-core SFPM machine, which has significantly less magnet and higher torque density than those of a conventional SFPM machine. The proposed machine has a simple structure. The main flux path of dc excitation does not affect the magnet excitation because it is not through magnets. The combination of stator and Rotor Pole numbers of the proposed machine is optimized, and the flux-enhancing and flux-weakening capabilities are investigated by 2-D finite-element analyses and experimentally validated.
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influence of slot opening on optimal stator and Rotor Pole combination and electromagnetic performance of flux switching pm brushless ac machines
Energy Conversion Congress and Exposition, 2010Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:The significant influence of slot opening on the optimal stator and Rotor Pole combination and the electromagnetic performance of the flux-switching PM (FSPM) machine is observed and investigated in this paper. A new FSPM brushless machine with remarkable slot opening relative to the magnet thickness is developed to reduce the magnet usage and increase the slot area. Its stator slot opening is almost several times of that in the conventional FSPM machine, but its magnet usage is only half. However, the new machine exhibits ∼40% larger back-emf and electromagnetic torque than those of the conventional machine, while its cogging torque and torque ripple are significantly lower.
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winding configurations and optimal stator and Rotor Pole combination of flux switching pm brushless ac machines
IEEE Transactions on Energy Conversion, 2010Co-Authors: J T Chen, Z Q ZhuAbstract:A simple analytical method is developed to compare the combinations of stator and Rotor Pole numbers in flux-switching permanent magnet (PM) machines in terms of back electromotive force (EMF) and electromagnetic torque. The winding connections and winding factors of machines having all Poles and alternate Poles wound, and different numbers of phases, from two to six, are determined by the coil-EMF vectors. Their differences from analyzing the conventional fractional-slot PM machines with concentrated nonoverlapping windings are highlighted. The general conditions are established for balanced symmetrical back-EMF waveform. It shows that the optimized Rotor Pole number should be close to the number of stator Poles, whereas larger torque can be obtained by the machine with relatively higher Rotor Pole number. The analysis is validated by finite-element analyses and experiment.
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advanced flux switching permanent magnet brushless machines
IEEE Transactions on Magnetics, 2010Co-Authors: Z Q Zhu, J T ChenAbstract:This paper overviews the recent development and new topologies of flux-switching (FS) machines, with particularly emphasis on the permanent magnet (PM) type. Specific design issues, including winding configurations, combinations of stator and Rotor Pole numbers, Rotor Pole width, split ratio, etc., are investigated, while the torque capability of selected FSPM machines is also compared.
R. Deodhar - One of the best experts on this subject based on the ideXlab platform.
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influence of slot opening on optimal stator and Rotor Pole combination and electromagnetic performance of switched flux pm brushless ac machines
IEEE Transactions on Industry Applications, 2011Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:The significant influence of slot opening on the optimal stator and Rotor Pole combination and on the electromagnetic performance of the switched-flux permanent magnet (SFPM) machine is observed and investigated in this paper. A new SFPM brushless machine with remarkable slot opening relative to the magnet thickness is developed to reduce the magnet usage and to increase the slot area. Its stator slot opening is almost several times of that in the conventional SFPM machine, but its magnet usage is only half. However, the new machine exhibits ~ 40% larger back EMF and electromagnetic torque than those of the conventional machine, while its cogging torque and torque ripple are significantly lower.
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a novel hybrid excited switched flux brushless ac machine for ev hev applications
IEEE Transactions on Vehicular Technology, 2011Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:A novel E-core hybrid-excited switched-flux permanent-magnet (SFPM) brushless machine is proposed based on an E-core SFPM machine, which has significantly less magnet and higher torque density than those of a conventional SFPM machine. The proposed machine has a simple structure. The main flux path of dc excitation does not affect the magnet excitation because it is not through magnets. The combination of stator and Rotor Pole numbers of the proposed machine is optimized, and the flux-enhancing and flux-weakening capabilities are investigated by 2-D finite-element analyses and experimentally validated.
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influence of slot opening on optimal stator and Rotor Pole combination and electromagnetic performance of flux switching pm brushless ac machines
Energy Conversion Congress and Exposition, 2010Co-Authors: J T Chen, Z Q Zhu, S Iwasaki, R. DeodharAbstract:The significant influence of slot opening on the optimal stator and Rotor Pole combination and the electromagnetic performance of the flux-switching PM (FSPM) machine is observed and investigated in this paper. A new FSPM brushless machine with remarkable slot opening relative to the magnet thickness is developed to reduce the magnet usage and increase the slot area. Its stator slot opening is almost several times of that in the conventional FSPM machine, but its magnet usage is only half. However, the new machine exhibits ∼40% larger back-emf and electromagnetic torque than those of the conventional machine, while its cogging torque and torque ripple are significantly lower.
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Analysis of electromagnetic performance of flux-switching permanent-magnet machines by nonlinear adaptive lumped parameter magnetic circuit model
IEEE Transactions on Magnetics, 2005Co-Authors: Y Pang, Shinji Iwasaki, R. Deodhar, David Howe, A. PrideAbstract:A nonlinear adaptive lumped parameter magnetic circuit model is developed to predict the electromagnetic performance of a flux-switching permanent-magnet machine. It enables the air-gap field distribution, the back-electromotive force (back-EMF) waveform, the winding inductances, and the electromagnetic torque to be calculated. Results from the model are compared with finite-element predictions and validated experimentally. The influence of end effects is also investigated, and optimal design parameters, such as the Rotor Pole width, the stator tooth width, and the ratio of the inner to outer diameter of the stator, are discussed.
Wei Hua - One of the best experts on this subject based on the ideXlab platform.
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analysis of stator slots and Rotor Pole pairs combinations of Rotor permanent magnet flux switching machines
IEEE Transactions on Industrial Electronics, 2020Co-Authors: Wei Hua, Zhe Chen, Ming ChengAbstract:This paper investigates the influence of stator slots and Rotor Pole pairs combinations on torque performances in Rotor permanent magnet flux switching (RPM-FS) machines. Based on a magnetomotive force (MMF) permeance model, the candidates of stator slots and Rotor Pole pairs combinations with higher torque capability can be determined by analyzing the PM-MMF and winding factor. Meanwhile, the candidates with a lower torque ripple can be obtained by referring to the cogging torque, which is related to the greatest common divisor of stator slots and Rotor Pole pairs. In addition, from the field modulation principle, the RPM-FS machines with the same fundamental magnetic loadings and winding factors exhibit identical fundamental harmonic torque, but different modulation harmonic components. Finally, four candidates with attractive torque performance are chosen, and the characteristics are verified by finite-element analysis and experiments.
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analysis and suppression of induced voltage pulsation in dc winding of five phase wound field switched flux machines
IEEE Transactions on Energy Conversion, 2019Co-Authors: Wei Hua, Sam Akehurst, Xiaofeng Zhu, Wentao Zhang, Junming ZhuAbstract:In wound-field (WF) switched flux (SF) (WFSF) machines, the DC winding induced voltage pulsation causes current ripple in the DC winding and challenges the DC power source, and deteriorates the control performance. In this paper, the induced voltage pulsation in DC winding of five-phase WFSF machines is analyzed and its reduction methods are proposed. The cycles per electric period of the open-circuit and armature reaction induced voltage pulsation in DC winding are derived analytically. Modifying the airgap permeance by optimizing the Rotor Pole arc or chamfering the Rotor Pole surface, and axial pairing of Rotor segments having Rotor Pole with different arcs are used to suppress the induced voltage pulsation in DC winding, with >90% average torque maintained. Finite element results show that, by optimizing the Rotor Pole arc, the peak-to-peak value of the induced voltage pulsation in DC winding can be effectively suppressed to 59.59%, 30.67%, 29.99% and 43.35% for the 10-stator-Pole five-phase WFSF machines with 8-, 9-, 11- and 12-Rotor-Pole Rotors, respectively. By applying Rotor Pole surface shaping, the induced voltage pulsation in DC winding peak-to-peak value can be effectively suppressed to 61.76%, 45.47% and 40.21% for the 8-, 9- and 12-Rotor-Pole machines, respectively, while by applying axial pairing, it can be suppressed to 46.89%, 7.16%, 15.64% and 12.04%, respectively. The 10-stator-Pole/12-Rotor-Pole WFSF machines having the original Rotor, optimized Rotor, chamfered Rotor and axial paired Rotor are prototyped and the experiments validate the analytical and finite element results.
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electromagnetic performance comparison between 12 phase switched flux and surface mounted pm machines for direct drive wind power generation
International Conference on Electrical Machines, 2018Co-Authors: Wei Hua, Ming Cheng, Lingyun Shao, Juliette Soulard, Z Q ZhuAbstract:In this paper, the 12-phase switched flux (SF) permanent magnet (PM) (SFPM) machine and two surface-mounted PM (SPM) machines designed for direct-drive wind power generation are comparatively analyzed. Firstly, feasible stator-slot/Rotor-Pole combinations for symmetrical 12-phase winding layout are investigated for both machine topologies. Secondly, the key design parameters of the PM generators are optimized by finite element (FE) analysis. Thirdly, electromagnetic performances including air-gap field, cogging torque, static torque, inductance, output voltage and its regulation factor, output power and efficiency of the generators are compared. A 10 kW 24-slot/22-Pole SFPM prototype is built and tested to validate the FE predicted results.
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influence of Rotor Pole number on electromagnetic performance in 12 phase redundant switched flux permanent magnet machines for wind power generation
IEEE Transactions on Industry Applications, 2017Co-Authors: Lingyun Shao, Wei Hua, Minghao Tong, Guishu Zhao, Fangbo Yin, Ming ChengAbstract:In this paper, electromagnetic performances of 12-phase 24-stator-Pole redundant switched flux permanent magnet (SFPM) machines with 20-, 22-, 26-, and 28-Rotor-Pole Rotors designed for wind power generation are comparatively analyzed. The influence of key design parameters on the open-circuit phase electromotive force and cogging torque is comparatively evaluated by a 2-D finite-element analysis (FEA). FEA results show that the 24-/26-Pole SFPM machine exhibits the highest electromagnetic torque and efficiency than the other three, while the 24-/22-Pole one has the smallest cogging torque and torque ripple as well as relatively good voltage regulation and efficiency, which are essential for a wind generator. Furthermore, the investigation on redundancy performance shows that cross coupling among the four sets of three-phase balanced windings and the saturation effect can be neglected when the generator operates with relative light loads. Finally, the 12-phase 24-/22-Pole SFPM machine is built and tested to validate the simulations.
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influence of Rotor Pole number on electromagnetic performance in twelve phase redundant sfpm machines for wind power generation
International Conference on Electrical Machines, 2016Co-Authors: Lingyun Shao, Wei Hua, Z Q Zhu, Ming ChengAbstract:In this paper, electromagnetic performances of twelve-phase 24-stator-slot redundant switched flux permanent magnet (SFPM) machines with 20-, 22-, 26- and 28-Rotor-Pole Rotors are analyzed. The influences of key design parameters on the open-circuit electro-motive-force (EMF) and cogging torque are comparatively evaluated by 2D finite-element analysis (FEA). FEA results show that the 24/26 SFPM machine exhibits the highest electromagnetic torque and efficiency than the other three, whilst the 24/22 one has the smallest cogging torque and torque ripple as well as relatively good power factor, voltage regulation and efficiency which are essential for a wind generator. Furthermore, the investigation on redundancy shows that cross-coupling among the four sets of three-phase balanced windings and the saturation effect can be neglected when the generator operates with light loads. Lastly, the prototyped twelve-phase 24/22 SFPM machine is measured to validate the simulations.
P Farah - One of the best experts on this subject based on the ideXlab platform.
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reduction of open circuit dc winding induced voltage in wound field switched flux machines by skewing
IEEE Transactions on Industrial Electronics, 2019Co-Authors: C Wang, J C Mipo, Sophie Personnaz, P FarahAbstract:In this paper, the open-circuit dc-winding-induced voltage in a wound field switched flux (WFSFs) machines is analyzed. The phenomenon of open-circuit dc-winding-induced voltage is illustrated and the mechanism is explained. Rotor skewing is proposed to reduce the open-circuit dc-winding-induced voltage, and the optimal skewing angle is analytically derived based on the analytically deduced harmonic orders of the open-circuit dc-winding-induced voltage. Finite-element (FE) analyses show that the open-circuit dc-winding-induced voltages in the analyzed 12-stator-Pole partitioned stator WFSF machines having 10-, 11-, 13-, and 14-Rotor-Pole Rotors can be effectively reduced by >94%, while the ac-winding phase-fundamental back-EMFs can be maintained by >95%. Twelve/ten-stator/Rotor-Pole prototypes with skewed and nonskewed Rotors are built and tested to verify the analytical and FE results.
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hybrid excited stator slot permanent magnet machines influence of stator and Rotor Pole combinations
IEEE Transactions on Magnetics, 2016Co-Authors: Z Q Zhu, J C Mipo, I A A Afinowi, Y Guan, P FarahAbstract:The hybrid-excited stator slot permanent magnet (HSSPM) machines have good flux regulation capability due to the dc excitation. This makes them attractive candidates for variable speed applications. In this paper, the choices of stator/Rotor Pole combinations for an arbitrary number of armature phases are discussed. The three-phase 12-10/11/13/14 stator/Rotor Poles HSSPM machines with single- and double-layer windings are further investigated. Their open-circuit characteristics, torque, inductances, and unbalanced magnetic forces are comparatively studied using 2-D finite-element analysis (FEA). Finally, the 2-D FEA is experimentally validated.
