Acoustic Noise Analysis of a Magnetically Geared Permanent Magnet Generator

Steffen Korsgaard, Anders Byrdal Kjær, Simon Staal Nielsen, Lorand Demsa, Peter Omand Rasmussen

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review


Recently, permanent magnet machines integrated in magnetic gears have been subject to research as it is possible to construct electrical machines with impressive torque densities. A 3.5 kW demonstrator of a magnetically geared permanent magnet generator is constructed and tested for potential implementation in a small wind turbine. However, acoustic noise at an unpleasant level is present during operation of the demonstrator. This paper investigates the origin of this acoustic noise as very limited knowledge in the area is present in the literature. A reduction in sound pressure level of 13 dB(A) is obtained by enclosing the initially open end shields of the machine with 3D-printed plugs. Analysis of electromagnetic forces in the air gaps has shown that the forces acting on the steel segment rotor are the noise source whereas improvements in the mechanical design is tested and a reduction of the acoustic noise is measured. Furthermore, a new retainer for the segment rotor is designed in glass fibre to decrease cost and number of parts to be manufactured. Also, the noise from the machine with the new retainer installed is compared to the noise from the original machine to determine if the new construction and material changes the dampening of the segment ring.
Original languageEnglish
Title of host publicationProceedings of 2019 IEEE Energy Conversion Congress and Exposition (ECCE)
Number of pages7
PublisherIEEE Press
Publication dateSep 2019
Article number8912892
ISBN (Electronic)9781728103952
Publication statusPublished - Sep 2019
Event2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, United States
Duration: 29 Sep 20193 Oct 2019


Conference2019 IEEE Energy Conversion Congress and Exposition (ECCE)
CountryUnited States
City Baltimore
SeriesIEEE Energy Conversion Congress and Exposition


  • Magnetic gears
  • Permanent magnet machines
  • Acoustic noise


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