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Z Q Zhu - One of the best experts on this subject based on the ideXlab platform.

  • analysis of stator rotor pole combinations in variable flux Reluctance machines using magnetic gearing effect
    2019
    Co-Authors: Liren Huang, Z Q Zhu, Jianghua Feng, Shuying Guo, J X Shi, W Q Chu
    Abstract:

    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.

  • analysis of stator rotor pole combinations in variable flux Reluctance machines using magnetic gearing effect
    2017
    Co-Authors: Liren Huang, Z Q Zhu, Jianghua Feng, Shuying Guo, J X Shi, W Q Chu
    Abstract:

    In this paper, the stator/rotor pole combinations in variable flux Reluctance machines (VFRMs) are investigated from the prospect of magnetic gearing effect. Firstly, the magnetic gearing effect in the Torque production of VFRMs is revealed from an analytical model. Based on this, the principles of feasible stator/rotor pole selection and corresponding winding configuration are analyzed. Then, the influence of stator/rotor pole combination on average Torque and Torque ripple production is investigated. It is found that the synchronous Torque is proportional to the 1st rotor radial permeance component and has the dominant contribution in average Torque production. Meanwhile, the 6-stator-slot/(6i±2)-rotor-pole (6s/(6i±2)r) and their multiples are large Torque ripple origins for VFRMs due to their significant large ripple in Reluctance Torque component. Moreover, a lower stator slot number is preferable choice to obtain higher Torque/copper loss ratio under low current density while a higher stator slot number is more suitable for high current density and large frame scale design. Finally, the analyses and conclusions are verified by finite element analysis (FEA) on the 6 and 12-stator-slot VFRMs and by experimental tests on a 6s/7r VFRM.

  • analysis of Torque production in variable flux Reluctance machines
    2017
    Co-Authors: Liren Huang, W Q Chu, Jianghua Feng, Shuying Guo, Junxu Shi, Z Q Zhu
    Abstract:

    In this paper, the Torque production mechanism of variable flux Reluctance machines (VFRMs) is investigated. Initially, based on an analytical instantaneous Torque model developed from the Lorentz force law and airgap field harmonic analysis, the magnetic gearing effect is revealed in the Torque production of VFRMs. Then, by using a 6-stator-pole/4-rotor pole (6s/4r) VFRM as an example, all its Torque components, including synchronous Torque, Reluctance Torque, and cogging Torque, are analyzed separately under linear condition. Their average Torque and Torque ripple characteristics are comprehensively illustrated. Finally, the influence of saturation effect is also accounted for with the help of finite element and frozen permeability methods. The analysis results are verified experimentally.

  • influence of pm and armature winding stator positions on electromagnetic performance of novel partitioned stator permanent magnet machines
    2017
    Co-Authors: J T Shi, Aimeng Wang, Z Q Zhu
    Abstract:

    Since the permanent magnets (PMs) and armature windings of partitioned stator (PS) PM machines are located in two separate inner and outer stators, their positions can be exchanged to optimize the space utilization, especially in radial field rotating machines. Therefore, in this paper, the influence of PM and armature winding stator positions on the electromagnetic performance of PS-PM machines is investigated based on the novel PS-PM machines (PS-PMMs) with surface-mounted PM (SPM) stator. Similar to the single-stator surface-mounted PMMs (SS-PMMs), flexible rotor pole number, bipolar phase flux linkage, and symmetrical phase back electromotive force (EMF) are also obtained in PS-PMMs. Based on the same 12/10 stator/rotor pole number combination, PS-PMM-I (PMs located in the inner stator) and PS-PMM-II (PMs located in the outer stator) exhibit 120% and 160% higher phase back EMFs as well as 120% and 139% larger average Torques, respectively, than the SS-PMM together almost without scarifying the PM utilization efficiency under the same machine size and the same rated copper loss. Further, the proposed PS-PMM-IIs have both higher phase back EMFs and larger average Torques than PS-PMM-Is among all the main stator/rotor pole number combinations. Meanwhile, for both PS-PMM-Is and PS-PMM-IIs with 12-pole stator, the machines with the 11-pole rotor exhibit the optimal Torque capabilities. Moreover, the Reluctance Torque is also negligible in the proposed PS-PMMs due to very low saliency ratio. The analyses are validated by experiment results of the prototype machine.

  • electromagnetic performance of novel synchronous machines with permanent magnets in stator yoke
    2014
    Co-Authors: J T Shi, Z Q Zhu, X Liu
    Abstract:

    Novel synchronous machines with doubly salient structure and permanent magnets (PMs) in stator yoke have been developed in this paper. The stator is constituted by T-shaped lamination segments sandwiched with circumferentially magnetized PMs with alternate polarity, while the rotor is identical to that of switched Reluctance machines (SRMs). The stator pole number is multiples of six, which is the number of stator poles in a unit machine. Similar to variable flux Reluctance machines (VFRMs), the rotor pole numbers in the novel machines are not restricted to those in SRMs. When the stator and rotor pole numbers differ by one (or the number of multiples), the novel synchronous machines show sinusoidal bipolar phase flux linkage and back electromotive force (EMF), which make the machines suitable for brushless ac operation. Moreover, two prototype machines with six-pole stator and five-pole, seven-pole rotors are designed and optimized by 2-D finite element analysis. It shows that, compared with VFRMs, the novel machines can produce ~70 % higher Torque density with the same copper loss and machine size. Meanwhile, the proposed machines have negligible Reluctance Torque due to very low saliency ratio. Experimental results of back EFM, cogging Torque, and average Torque on the prototypes are provided to validate the analysis.

A M Elrefaie - One of the best experts on this subject based on the ideXlab platform.

  • effect of number of layers on performance of fractional slot concentrated windings interior permanent magnet machines
    2015
    Co-Authors: Patel Bhageerath Reddy, A M Elrefaie, Kumkang Huh
    Abstract:

    Interior PM machines equipped with fractional-slot concentrated-windings are good candidates for high-speed traction applications. This is mainly due to the higher power density and efficiency that can be achieved. The main challenge with this type of machines is the high rotor losses at high speeds/frequencies. This paper will thoroughly investigate the effect of number of winding layers on the performance of this type of machines. It will be shown that by going to higher number of layers, there can be significant improvement in efficiency especially at high speeds mainly due to the reduction of the winding factor/magnitude of the most dominant stator mmf subharmonic component. It will also be shown that there is significant improvement in Torque density. Even though there is reduction in the winding factor of the stator synchronous Torque-producing mmf component, this is more than offset by increase in machine saliency and Reluctance Torque. The paper will provide general guidelines regarding the optimum slot/pole/phase combinations based on Torque density and efficiency. Sample designs of various slot/pole combinations are used to quantify the benefit of going to higher number of layers in terms of Torque density, efficiency, and Torque ripple.

  • unsaturated and saturated saliency trends in fractional slot concentrated winding interior permanent magnet machines
    2010
    Co-Authors: Jagadeesh Tangudu, Thomas M Jahns, A M Elrefaie
    Abstract:

    This paper presents an investigation of trends in the unsaturated and saturated magnetic saliency values of interior permanent magnet (IPM) synchronous machines with fractional-slot concentrated windings (FSCW). This paper investigates alternative slot-pole combinations for FSCW-IPM machines, highlighting the key observation that the saliency of these machines is generally lower than their counterpart IPM machines with conventional distributed windings. The relative merits and challenges of FSCW-IPM machines are examined, with a focus on the contribution of Reluctance Torque to the total machine Torque. A key design metric that proves useful in this discussion is “unsaturated saliency ratio”, defined as the ratio L q /L d in the limiting case of near zero stator current and “saturated saliency ratio”, defined as the ratio L q /L d at high stator current. An important objective is to use this parameter to help machine designers choose the most appropriate slot-pole configuration for an FSCW-IPM machine in order to achieve the desired performance requirements.

  • winding inductances of fractional slot surface mounted permanent magnet brushless machines
    2009
    Co-Authors: A M Elrefaie, Z Q Zhu, Thomas M Jahns, D Howe
    Abstract:

    Purpose – Permanent magnet (PM) brushless machines equipped with fractional‐slot concentrated‐windings (FSCW) have been receiving considerable attention over the past few years, due to the fact that they have short end‐windings, a high‐slot fill factor, a high efficiency and power density, and good flux‐weakening and fault‐tolerance capabilities. A key design parameter for such machines is the phase winding inductance since this has a significant impact on the performance, as well as on the magnitude of any Reluctance Torque. The purpose of this paper is to describe a detailed investigation of the various components of the winding inductance in machines equipped with both overlapping and non‐overlapping windings and different slot/pole number combinations. It also examines the influence of key design parameters, which affect the inductance components, with particular reference to the inductances of machines in which all the teeth are wound and those in which only alternate teeth are wound.Design/methodolo...

  • winding inductances of fractional slot surface mounted permanent magnet brushless machines
    2008
    Co-Authors: A M Elrefaie, Z Q Zhu, Thomas M Jahns, D Howe
    Abstract:

    Permanent magnet (PM) brushless machines equipped with fractional-slot concentrated-windings (FSCW) have been receiving considerable attention over the past few years, due to the fact that they have short end-windings, a high slot fill factor, a high efficiency and power density, and good flux- weakening and fault-tolerance capabilities. A key design parameter for such machines is the phase winding inductance since this has a significant impact on the performance, as well as on the magnitude of any Reluctance Torque. The paper describes a detailed investigation of the various components of the winding inductance in machines equipped with both overlapping and non- overlapping windings and different slot/pole number combinations. It also examines the influence of key design parameters, which affect the inductance components, with particular reference to the inductances of machines in which all the teeth are wound and those in which only alternate teeth are wound. It is shown that the main component of the winding inductance is the relatively large slot leakage component. Both analytical and finite element models are employed and predicted results are validated on several prototype machines.

Nicola Bianchi - One of the best experts on this subject based on the ideXlab platform.

  • Line-Start PM-Assisted Synchronous Motor Design, Optimization, and Tests
    2017
    Co-Authors: Damiano Mingardi, Nicola Bianchi
    Abstract:

    Line-start synchronous motors (LSSMs) have been recently introduced in the motor market to meet the new efficiency class requirements. They exhibit high efficiency and power factor compared with induction motors (IMs), but the complex design, manufacture, and high cost due to presence of permanent magnets (PM) limit their widespread use. This paper proposes a new approach for the design of LSSMs, in which an important Torque contribution is given by the Reluctance Torque component. Both steady-state and dynamic capabilities are considered. A stochastic optimization is used to determine the parameters that maximize the synchronous Torque. The possibility to apply the recent improvements on the synchronous Reluctance machine design to LSSMs is discussed. Experimental measurements are carried out on an LSSM prototype achieved from the optimization. The results are compared with the predictions. Two different PM volumes are tested in the same rotor structure, evaluating their impact on motor performance. From the experimental tests, an overview comparison between the IM and LSSM performance is given.

  • interior pm machines using ferrite to substitute rare earth surface pm machines
    2012
    Co-Authors: Massimo Barcaro, Nicola Bianchi
    Abstract:

    Since the cost of rare-earth permanent magnet (PM), such as NdFeB and SmCo, is more and more increasing, there is a great interest in designing PM machines without adopting such a rare-earth PMs, that is, replacing them with cheaper Ferrite magnet. Referring to the interior PM machines, the expected performance reduction is limited thanks to the anisotropic structure, compensating the use of low energy PMs by means of the Reluctance Torque component. This paper investigates the convenience of adopting Ferrite magnet in an interior PM machine (sometimes also referred to as PM assisted synchronous Reluctance machine), instead of rare-earth surface PM machine. It is shown that, even though a slight lengthening of the stack length, the anisotropic PM machines, using Ferrite magnets, may represents a valid competitor of a surface PM machine.

  • sensorless rotor position detection capability of a dual three phase fractional slot ipm machine
    2012
    Co-Authors: Massimo Barcaro, Nicola Bianchi, Adriano Faggion, Silverio Bolognani
    Abstract:

    The interest for fractional-slot permanent-magnet (PM) synchronous machines has been more and more increasing in recent years. Particularly attractive is the interior PM (IPM) machine, since it is characterized by two Torque components: the PM Torque and the Reluctance Torque. Owing to this feature, the IPM machine is able to operate under flux-weakening conditions, as required by many applications, such as automotive, machine tools, washing machines, and so on. Another feature is that the rotor position can be detected without sensor even at zero speed, by means of techniques based on high-frequency signal injection. The aim of this paper is to investigate the Torque components and the sensorless position detection capability of an IPM dual three-phase machine equipped with two fractional-slot windings. These two windings are designed to be supplied by two separate converters, yielding an increase of the fault-tolerant capability of the machine. The analysis and the tests deal with the capability of the machine when it operates under healthy as well as faulty conditions, i.e., when the supply of one three-phase winding set is switched off and only one winding continues to be supplied.

  • Sensorless rotor position detection capability of a dual three-phase fractional-slot IPM machine
    2012
    Co-Authors: Massimo Barcaro, Nicola Bianchi, Adriano Faggion, Silverio Bolognani
    Abstract:

    The interest for fractional-slot permanent magnet (PM) synchronous machines is more and more increasing in recent years. Particularly attractive is the interior PM (IPM) machine, since it is characterized by two Torque components: the PM Torque and the Reluctance Torque. Thanks to this feature, the IPM machine is able to operate under flux-weakening conditions, as required by many applications, such as automotive, machine tools, washing machines, and so on. Another feature is that the rotor position can be detected without sensor also at zero speed, by means of techniques based on high-frequency signal injection. The aim of this paper is to investigate the Torque components and the sensorless position detection capability of an IPM dual three-phase machine equipped with two fractional-slot windings. These two windings are designed to be supplied by two separate converters, yielding an increase of the fault-tolerant capability of the machine. The analysis and the tests presented deal with the capability of the machine when it operates under healthy as well as faulty conditions, that is, when one three-phase winding set is removed and only one continues to be supplied.

Seungdeog Choi - One of the best experts on this subject based on the ideXlab platform.

  • optimal phase advance under fault tolerant control of a five phase permanent magnet assisted synchronous Reluctance motor
    2018
    Co-Authors: Akm Arafat, Seungdeog Choi
    Abstract:

    In this paper, optimal phase advances under fault-tolerant control (FTC) of a five-phase permanent magnet assisted synchronous Reluctance motor (PMa-SynRM) have been proposed under different fault conditions. Critical applications where the consistency and safety are the major concerns in automotive and aerospace industries require reliable control systems. The multiphase motor is considered a promising candidate for these applications as it has redundant phases primarily for fault-tolerant operation. However, advanced FTC for a PMa-SynRM with maximization of Reluctance Torque has been limitedly studied until now. In the conventional approach, to maintain constant magnetomotive force under fault conditions, phase currents of a motor need to increase significantly. However, this will easily saturate the PMa-SynRM resulting in significantly reduced Reluctance Torque. To overcome this issue, this paper proposes a novel phase current control method that maximizes the Reluctance Torque with minimum phase current. Here, a phase current control with a novel phase advance has been proposed under various fault conditions. Extensive theoretical and experimental analysis has been carried out to verify the effectiveness of the proposed idea with 5-hp dynamo system controlled by TI DSP F28335.

  • open phase fault detection of a five phase permanent magnet assisted synchronous Reluctance motor based on symmetrical components theory
    2017
    Co-Authors: Akm Arafat, Seungdeog Choi, Jeihoon Baek
    Abstract:

    This paper presents a novel approach for open-phase fault detection of a five-phase permanent magnet assisted synchronous Reluctance motor (PMa-SynRM). Under faults, the five-phase PMa-SynRM is expected to run at fault-tolerant control (FTC) mode, otherwise it draws a large amount of current with a significant reduction in the Reluctance Torque. To successfully achieve FTC operation of five-phase PMa-SynRM, the accurate detection of a fault condition has to be preceded. With the best of these authors knowledge, the detection of faults has been limitedly studied for five-phase motors. The analysis of open-phase fault in five-phase machine involves complicated conditions including single-phase open fault, two-phase adjacent fault, and two-phase nonadjacent fault. To perform the timely fault-tolerant operation, those faults have to be accurately analyzed and detected. In this paper, a novel symmetrical components (SCs) analysis is utilized to extract the feature of those fault conditions. This analysis will provide the types of faults by logically analyzing the pattern of magnitude and phase angle changes of the fundamental signal in the SCs. The proposed method has been comprehensively analyzed through theoretical derivation, finite-element simulations, and experimental testing through a 5 hp PMa-SynRM controlled by TI-DSP F28335.

Akm Arafat - One of the best experts on this subject based on the ideXlab platform.

  • optimal phase advance under fault tolerant control of a five phase permanent magnet assisted synchronous Reluctance motor
    2018
    Co-Authors: Akm Arafat, Seungdeog Choi
    Abstract:

    In this paper, optimal phase advances under fault-tolerant control (FTC) of a five-phase permanent magnet assisted synchronous Reluctance motor (PMa-SynRM) have been proposed under different fault conditions. Critical applications where the consistency and safety are the major concerns in automotive and aerospace industries require reliable control systems. The multiphase motor is considered a promising candidate for these applications as it has redundant phases primarily for fault-tolerant operation. However, advanced FTC for a PMa-SynRM with maximization of Reluctance Torque has been limitedly studied until now. In the conventional approach, to maintain constant magnetomotive force under fault conditions, phase currents of a motor need to increase significantly. However, this will easily saturate the PMa-SynRM resulting in significantly reduced Reluctance Torque. To overcome this issue, this paper proposes a novel phase current control method that maximizes the Reluctance Torque with minimum phase current. Here, a phase current control with a novel phase advance has been proposed under various fault conditions. Extensive theoretical and experimental analysis has been carried out to verify the effectiveness of the proposed idea with 5-hp dynamo system controlled by TI DSP F28335.

  • open phase fault detection of a five phase permanent magnet assisted synchronous Reluctance motor based on symmetrical components theory
    2017
    Co-Authors: Akm Arafat, Seungdeog Choi, Jeihoon Baek
    Abstract:

    This paper presents a novel approach for open-phase fault detection of a five-phase permanent magnet assisted synchronous Reluctance motor (PMa-SynRM). Under faults, the five-phase PMa-SynRM is expected to run at fault-tolerant control (FTC) mode, otherwise it draws a large amount of current with a significant reduction in the Reluctance Torque. To successfully achieve FTC operation of five-phase PMa-SynRM, the accurate detection of a fault condition has to be preceded. With the best of these authors knowledge, the detection of faults has been limitedly studied for five-phase motors. The analysis of open-phase fault in five-phase machine involves complicated conditions including single-phase open fault, two-phase adjacent fault, and two-phase nonadjacent fault. To perform the timely fault-tolerant operation, those faults have to be accurately analyzed and detected. In this paper, a novel symmetrical components (SCs) analysis is utilized to extract the feature of those fault conditions. This analysis will provide the types of faults by logically analyzing the pattern of magnitude and phase angle changes of the fundamental signal in the SCs. The proposed method has been comprehensively analyzed through theoretical derivation, finite-element simulations, and experimental testing through a 5 hp PMa-SynRM controlled by TI-DSP F28335.