Mohd Saufi Ahmad
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Preferred name
Mohd Saufi Ahmad
Official Name
Mohd Saufi , Ahmad
Alternative Name
Ahmad, M. S.
Ahmad, Mohd Saufi
Main Affiliation
Scopus Author ID
57214108987
Researcher ID
AAK-3467-2020

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  • Publication
    Analytical subdomain model for Double-Stator Permanent Magnet Synchronous Machine
    (Springer Science and Business Media Deutschland GmbH, 2022-01-01)
    Mohd Saufi Ahmad
    ;
    Ishak D.
    ;
    Rezal M.
    ;
    Tiang Tow Leong
    ;
    Jamil M.K.M.
    This paper presents an analytical subdomain model for predicting the magnetic field distributions in three-phase double-stator permanent magnet synchronous machine (DS-PMSM) during open-circuit and on-load conditions. The model is initially derived based on Laplace’s and Poisson’s equations in polar coordinates by separation of variables technique in four subdomains, i.e., outer airgap, outer magnet, inner magnet and inner airgap. The field solutions in each subdomain are obtained by applying the appropriate boundary conditions and interface conditions. Finite element analysis (FEA) is later deployed to validate the analytical results in DS-PMSM having different number of slots between outer and inner stators with a non-overlapping winding arrangement. The analyzed electromagnetic performances are slotless airgap flux density waveform, back-emf waveform and output torque waveform. The results show that the proposed analytical model can accurately predict the magnetic field distributions in DS-PMSM.
  • Publication
    Modelling of air-gap magnetic flux density distribution for surface-mounted Permanent Magnet Synchronous Motor using the analytical sub-domain method
    (Springer Science and Business Media Deutschland GmbH, 2022-01-01)
    Rezal M.
    ;
    Ishak D.
    ;
    Mohd Saufi Ahmad
    This paper discusses an analytical modelling for a slotless surface-mounted permanent magnet synchronous motor (PMSM) at airgap region using the sub-domain method. The slotless PMSM has no cogging effect compared to a slotted PMSM. The radial magnetization of the magnetic flux is applied in the motor design with 6-slot/4-pole configuration. The analytical model of magnetic flux density distributions shows a good agreement with the numerical results from finite element analysis.
  • Publication
    Comparative evaluation of three-phase double stator pmsm with different slot number in inner and outer stators
    ( 2020-04-11)
    Mohd Saufi Ahmad
    ;
    Ishak D.
    ;
    Firdaus R.N.
    ;
    Mohamed M.R.
    This paper presents a comparative evaluation of three-phase double-stator permanent magnet synchronous machines (DS-PMSM) in which the slot number of outer stator is different than that of the inner stator. The fractional-slot machine type is considered in both inner and outer stators. The rotor core material which can be either iron-core or air-core is analyzed in order to evaluate the magnetic performance of DS-PMSM. In addition, several models of the proposed DS-PMSM with different rotor magnet pole arc have been investigated. Finite element method (FEM) is employed intensively to predict the flux line distribution, flux density distribution, back-emf, cogging torque, output torque and torque ripple for each model. Systematic comparison is further conducted for different rotor materials. The results show that the rotor with iron-core is eminently appropriate for better torque density, but it suffers higher torque ripple. While the rotor with air-core structure has advantage in producing smaller cogging torque and almost ripple-free output torque.
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