A coupler consisting of a primary winding at room temperature and a secondary winding at cryogenic temperature, which may or may not be superconducting. The coupler is designed for power line frequencies (e.g. 50 or 60 Hz) or much higher frequencies and overcomes challenges with the transition of power from room temperature to the cryogenic environment. By coupling the power via magnetic fields using the power transformer principle, this coupling mechanism can achieve voltage transformation which galvanic feedthroughs cannot. The method can also be applied as a brushless exciter for superconducting motors and generators.
