Statistical analysis of the effect of magnet placement on cogging torque in fractional pitch permanent magnet motors

Greg Heins, Travis Brown, Mark Thiele

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Theoretically, the layout of fractional pitch permanent magnet motors should ensure the cancellation of most cogging torque harmonics. In reality, manufacturing errors lead to incomplete cancellation and higher than expected cogging torque. One potential manufacturing error is the variation in angle between neighboring magnets. This paper uses the superposition technique to analytically determine the expected magnitude of each cogging torque harmonic based on a Gaussian distribution of angular magnet placement variation. A simple expression is presented for the expected value of each harmonic's magnitude based upon the harmonic number, the number of magnets, and the standard deviation of the Gaussian placement distribution. The derived expression is validated using Monte Carlo simulations and experimental implementation.
    Original languageEnglish
    Pages (from-to)2142-2148
    Number of pages7
    JournalIEEE Transactions on Magnetics
    Volume47
    Issue number8
    DOIs
    Publication statusPublished - 2011

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    Permanent magnets
    Magnets
    Statistical methods
    Torque
    Gaussian distribution
    Plant layout
    Monte Carlo simulation

    Cite this

    @article{078eaf291f7346faba308262f1ac5853,
    title = "Statistical analysis of the effect of magnet placement on cogging torque in fractional pitch permanent magnet motors",
    abstract = "Theoretically, the layout of fractional pitch permanent magnet motors should ensure the cancellation of most cogging torque harmonics. In reality, manufacturing errors lead to incomplete cancellation and higher than expected cogging torque. One potential manufacturing error is the variation in angle between neighboring magnets. This paper uses the superposition technique to analytically determine the expected magnitude of each cogging torque harmonic based on a Gaussian distribution of angular magnet placement variation. A simple expression is presented for the expected value of each harmonic's magnitude based upon the harmonic number, the number of magnets, and the standard deviation of the Gaussian placement distribution. The derived expression is validated using Monte Carlo simulations and experimental implementation.",
    keywords = "Analytical model, Cogging torque, Mass production, permanent magnet machines, Statistical distribution, AC motors, Angular distribution, Computer simulation, Harmonic analysis, Magnetic devices, Manufacture, Mathematical models, Monte Carlo methods, Permanent magnets, Torque",
    author = "Greg Heins and Travis Brown and Mark Thiele",
    year = "2011",
    doi = "10.1109/TMAG.2011.2125795",
    language = "English",
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    pages = "2142--2148",
    journal = "IEEE Transactions on Magnetics",
    issn = "0018-9464",
    publisher = "IEEE, Institute of Electrical and Electronics Engineers",
    number = "8",

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    Statistical analysis of the effect of magnet placement on cogging torque in fractional pitch permanent magnet motors. / Heins, Greg; Brown, Travis; Thiele, Mark.

    In: IEEE Transactions on Magnetics, Vol. 47, No. 8, 2011, p. 2142-2148.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Statistical analysis of the effect of magnet placement on cogging torque in fractional pitch permanent magnet motors

    AU - Heins, Greg

    AU - Brown, Travis

    AU - Thiele, Mark

    PY - 2011

    Y1 - 2011

    N2 - Theoretically, the layout of fractional pitch permanent magnet motors should ensure the cancellation of most cogging torque harmonics. In reality, manufacturing errors lead to incomplete cancellation and higher than expected cogging torque. One potential manufacturing error is the variation in angle between neighboring magnets. This paper uses the superposition technique to analytically determine the expected magnitude of each cogging torque harmonic based on a Gaussian distribution of angular magnet placement variation. A simple expression is presented for the expected value of each harmonic's magnitude based upon the harmonic number, the number of magnets, and the standard deviation of the Gaussian placement distribution. The derived expression is validated using Monte Carlo simulations and experimental implementation.

    AB - Theoretically, the layout of fractional pitch permanent magnet motors should ensure the cancellation of most cogging torque harmonics. In reality, manufacturing errors lead to incomplete cancellation and higher than expected cogging torque. One potential manufacturing error is the variation in angle between neighboring magnets. This paper uses the superposition technique to analytically determine the expected magnitude of each cogging torque harmonic based on a Gaussian distribution of angular magnet placement variation. A simple expression is presented for the expected value of each harmonic's magnitude based upon the harmonic number, the number of magnets, and the standard deviation of the Gaussian placement distribution. The derived expression is validated using Monte Carlo simulations and experimental implementation.

    KW - Analytical model

    KW - Cogging torque

    KW - Mass production

    KW - permanent magnet machines

    KW - Statistical distribution

    KW - AC motors

    KW - Angular distribution

    KW - Computer simulation

    KW - Harmonic analysis

    KW - Magnetic devices

    KW - Manufacture

    KW - Mathematical models

    KW - Monte Carlo methods

    KW - Permanent magnets

    KW - Torque

    U2 - 10.1109/TMAG.2011.2125795

    DO - 10.1109/TMAG.2011.2125795

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    EP - 2148

    JO - IEEE Transactions on Magnetics

    JF - IEEE Transactions on Magnetics

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