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Yazdan, Tanveer,Kwon, Byung-il Institution of Electrical Engineers 2018 IET electric power applications Vol.12 No.7
<P>This study proposes a two-phase single-air-gap axial flux permanent magnet (AFPM) motor that offers a trapezoidal back-electromotive force (EMF) waveform to improve the performance of the only-pull drive technique compared with the radial flux PM (RFPM) motor. The only-pull drive technique provides the benefit of allowing the use of thin magnets in the motor without suffering from irreversible demagnetisation. In the proposed motor, the design geometry is primarily considered to achieve the desired trapezoidal shape of back-EMF. The effects of the geometry are explained with the help of air-gap flux density, flux linkage, and the leakage flux. Both the radial flux and the proposed motor adopt the same design concept and hold equal electromagnetic loadings. The profile of back-EMF and the electromagnetic torque driven by the only-pull drive technique are compared with that of RFPM motor with non-trapezoidal back-EMF. Furthermore, the split configuration is proposed for the AFPM motor to reduce torque ripples. The demagnetisation analysis is performed to confirm the operating point of the magnets in a split-AFPM motor. The results reveal that the AF motor is a good candidate for the only-pull drive technique.</P>
A Novel Technique for Two-Phase BLDC Motor to Avoid Demagnetization
Yazdan, Tanveer,Zhao, Wenliang,Lipo, Thomas A.,Kwon, Byung-Il IEEE 2016 IEEE transactions on magnetics Vol.52 No.7
<P>Conventional permanent magnet (PM) motors operate in both magnetizing (pull) process and reversible demagnetizing (push) process on the recoil line of magnets. Therefore, thin-surface PMs may easily undergo a risk of demagnetization at the push process under certain fault conditions, which lead to deterioration of motor performance. Thus, thick magnets, whereas contributing the significantly high cost, are usually used to minimize this risk in the PM motors. In this paper, a novel operation technique, that involves only the pull process, has been proposed for a unique design of two-phase brushless DC motor to avoid the irreversible demagnetization of the magnets. The motor, operated only in the pull process, is kept away from the push process of the operation. Therefore, the motor sustains its initial magnetic operating point above the knee point during the normal operation as well as under the short circuit fault conditions. Finite-element analysis is performed to validate the concept of the proposed technique.</P>
Dual three Phase Operation of Dual Airgap Permanent Magnet Vernier Machine Having a Yokeless Rotor
Siddiqi Mudassir Raza,Yazdan Tanveer,Humza Muhammad,Ahmad Ikhlaq,Hur Jin 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4
In order to increase the speed range of permanent magnet machines in constant power regions, diff erent techniques including multi-phase confi gurations are usually adopted. This paper presents the dual three-phase operation of a novel dual-airgap permanent magnet vernier machine having a yokeless rotor. The presented machine comprises two stators, each having a three-phase winding, and a sandwiched single yokeless rotor. The outer and inner stator windings are treated as two diff erent sets of three-phase windings to accomplish the dual three-phase operation. To achieve this, three-phase currents are supplied to these winding sets by considering two cases: (i) out-of-phase currents having the same magnitude and (ii) in-phase currents with varying magnitudes. This dual three-phase operation provides better effi ciency in the in-phase operation. The presented yokeless model has a very high mutual inductance which improves the fl ux linkage between two stators. Moreover, the harmonic analysis and open circuit fault analysis are presented to confi rm the validity of the presented dual three-phase operation compared to the three-phase operation. 2D-FEM analysis is used to investigate the performance of the presented machine for dual three-phase operation.