Capacitive coupling through a hydrodynamic journal bearing to power rotating electrical loads without contact

A capacitive power coupler has been devised using a hydrodynamic journal bearing assembly that facilitates sufficient coupling for kilowatt-scale non-contact power transfer to a rotating load. The capacitive coupler, combined with associated driving circuitry, is an efficient low maintenance solution for powering a variety of rotating or pivoting electrical loads in machines and automation. A hydrodynamic journal bearing capacitor assembly utilizing an ultra-thin cushion of lubricant as dielectric between concentric capacitor electrodes is presented. Hydrodynamic operation ensures high coupling capacitance, ease of manufacturability and eliminates brush and slip ring maintenance. The system´s small size, weight, and simplicity are competitive with contemporary inductive wireless power transfer methods in this small gap application. Experimental results for a ~5nF prototype coupler operating at 840 kHz are presented.