Abstract: A sealed transformer for use in charging the batteries of an electric automobile includes a housing that contains the secondary windings, a core and a dielectric fluid. A removable primary winding coupler is inserted into the housing to complete a magnetic circuit. During operation of the magnetic circuit, heat is continuously generated by the primary and secondary windings and the core. The fluid undergoes a first phase change and boils as it absorbs the generated heat. The boiling fluid absorbs additional heat and undergoes a second phase change is it turns into a vapor. The heat of vaporization is released into thin windows formed in the transformer housing when the vapors contact the relatively cooler windows and re-condense into a liquid. A continuous cycle of boiling, vaporizing, and condensing occurs during operation of the transformer to cool the transformer and to improve the power density of the transformer.

Abstract: A charging system employing a liquid-cooled transmission cable for transferring power. The transmission cable has a central tube with an extruded member disposed therewithin for carrying coolant. A plurality of layers of coaxial tubular wire braid are disposed around the central tube that carry charging current and that are separated by a layers of dielectric material. An outer layer of wire braid is disposed around an outermost layer of dielectric material that is used for grounding and/or shielding. An outer jacket is disposed around the outer layer of wire braid for encasing the transmission cable. The extruded member may comprise a thermoplastic rubber extrusion, for example. The coolant path through the transmission cable is internally supported by means of the extruded member to assure uniform flexibility, maintain tangential magnetic flux, and eliminate kinking and collapse of the flow path.