PURPOSE: To get over a skin effect caused at a high frequency for making a reduced-size and light-weight transformer by making a plurality of grooves on the surface of a secondary coil and by providing a cooling water path through the secondary coil to cool it down.
CONSTITUTION: With high-frequency ac power input into a primary coil 10, a same-frequency ac electromotive force is induced between both ends 16 and 18 of a secondary coil 12. the ac electromotive force is converted by rectifying devices 24, 24 into dc to be output from between center-tap terminal strips 24 and 20. At this time, a high-frequency large current flows in the secondary coil 12, resulting in generation of heat and skin effect which would increase an energy loss. However, heat generation is controlled by cooling water which is running in a cooling water path 28. The cooling water path 28 through the secondary coil 12 and the grooves 30 on the surface of the secondary coil 12 remarkably increase a surface area of the secondary coil 12, with a result of a sharp reduction of energy loss which would be caused by a skin effect.
KOBAYASHI NOBUO
TAKANO FUMITOMO
