REBCO Coils System for Axial Flux Electrical Machines Application: Manufacturing and Testing

A REBCO coil system for axial flux electrical machines applications is presented. Three couples of series-connected coils have been placed on a fiberglass disc and wired in star configuration to simulate a three-phase, ironless, and superconducting armature concentrated winding. REBCO-based commercial tape has been used to wind each of the six coils in double-pancake configuration around a fiberglass trapezoidal-shaped core. DC current-voltage curve and ac transport current losses plots of each coil have been obtained at liquid nitrogen temperature. Six copper coils having the same shape and geometric parameters of REBCO coils have been also manufactured to assemble a conventional armature concentrated winding. Laboratory testing on different armature windings has been conducted at different temperatures (77 K and 300 K) to measure the impedance (amplitude and phase) value, the back electromotive forces waveform, etc. The experimental results of both configurations (conventional and superconducting) are compared to study the feasibility of a superconducting armature winding prototype of an axial flux electric machine.