Modeling and Design of a 6-Phase Ultra-High-Speed Machine for ELF/VLF Wireless Communication Transmitter

This paper presents the modeling, design, and Multiphysics analysis of a 2000-W, 500000-rpm ultra-high-speed (UHS) machine for a mechanical-based antenna (AMEBA) application. The proposed machine will be utilized as a mechanical transmitter for extremely/very low frequency (0.3-3 kHz) communication, which will immediately enable the bidirectional communication between the earth surface to underground or undersea facilities. The design of a UHS machine for AMEBA application presents several special challenges because it requires a high shaft torque at UHS operation. Also, the UHS machine necessitates a high design-safety-margin to avoid any catastrophic failure at the UHS operation. However, a conventional 3-phase UHS machine cannot meet the torque requirement, thermal limit, structural integrity, and fails to provide enough safety margin at UHS operation. To overcome this limitation, this paper presents the design of a high-power UHS machine, which utilizes a multi- phase winding configuration and special materials to improve the torque density and the design-safety-margin. The machine geometry and design parameters are optimized using a Multiphysics loss minimization approach. The proposed design and its performance are analyzed using extensive finite element analysis (FEA). It is observed that the proposed design meets the electromagnetic, thermal, structural, and Rotordynamic performance with a greater design-safety-margin. Finally, a prototype of the proposed machine is developed and its performances (back-EMF and natural frequencies) are experimentally validated.