Design, Fabrication, Test, and Benchmark of a Magnetically Geared Permanent Magnet Generator for Wind Power Generation

Magnetic gears with an integrated permanent magnet machine provides advantages within the field of wind turbine drive trains compared to both mechanically geared generators due to non physical contact between rotors as well as direct driven generators where size and weight can be reduced. Theoretical and practical benchmark of the technology against commercial direct drive generators with regards to material use and performance is yet to be found in the literature. In this article, a magnetically geared permanent magnet generator is designed with operational specifications based on a commercial 3.5 kW permanent magnet generator designed for direct drive wind turbines. A demonstrator is fabricated and the design models are validated experimentally. Performance and material use for both the demonstrator and the direct drive generator is mapped. The experimentally verified results are used for benchmarking and the comparison shows promising results as both size and weight is significantly reduced for similar performance. It is also found that the material consumption is reduced, and contrary to popular belief, the use of magnet material in the magnetically geared machine is actually less than that of the benchmark generator.