Frequency and operational characteristics of an ultra-lightweight machine converting energy by magnetic resonance coupling

• Main Authors: Kazuto Sakai, Kenta Takishima
• Format: Article
• Language: English
• Published: Wiley 2019-04-01
• Series: The Journal of Engineering
• Subjects: electric generators; torque; rotors; stators; finite element analysis; electric drives; electric motors; magnetic cores; inductive power transmission; magnetic resonance; starting; electric machines; operational characteristics; ultra-lightweight machine converting energy; magnetic resonance coupling; electric aircraft; minimal energy; electrical energy; stator; rotor; electromagnetic resonance coupling technology; electrical machines; magnetic core; basic characteristics; MRC machine; rotational energy conversion; rotating machine; magnetic energy; resonant frequency
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8185

Electric aircrafts capable of moving in three dimensions cause creation of new industries and applications in society. Also, electric aircrafts operate on minimal energy with low emissions. However, an electric aircraft must be ultra-lightweight. To produce an ultra-lightweight machine for electric aircrafts, the authors proposed a machine in which electrical energy is converted between the stator and rotor through magnetic resonance coupling (MRC). This action causes electromagnetic resonance between the multiphase windings of the stator and rotor. Electromagnetic resonance coupling technology allows electrical machines to convert energy without a magnetic core, thereby allowing the production of ultra-lightweight machines. In this study, authors describe a machine with three-phase windings based on MRC and discuss its operating principles and the basic characteristics induced by MRC. A model of this MRC machine was subjected to magnetic analyses to assess its rotational energy conversion in a rotating machine and to understand its basic characteristics. Authors’ results confirmed that MRC machines without a magnetic core could convert magnetic energy between the stator and rotor and produce sufficient starting torque and power at a power factor of 1.0. Furthermore, the machine was highly efficient, and its torque increased with resonant frequency.