Considerations on the performance characteristics of a planar magnetic path-type parametric microtransformer

Abstract

Over the past few years, a large number of studies have been made on inductors and transformers for micro dc-to-dc converters which will be used in personal phones, card-type electronic devices, and so forth. A planar parametric transformer, which has already been proposed by us, has various desirable features including voltage regulation, overload protection, and noise rejection. The transformer is comprised of a stack of five amorphous Fe5Co70Si15B10 alloy 0.03-mm-thick laminations fabricated by the wire-electric discharge machine, and is composed of a magnetic path with three legs and end bars connecting the ends of those legs. Slots are made in the centers of the outside edges of the end bars to prevent the magnetic flux in each side leg from entering the other side leg. These slots cause a parametric oscillation in the transformer. This paper discusses the fundamental performance characteristics of a 5 × 7 mm transformer and studies the conditions for generating parametric oscillations in a planar transformer, in order to elucidate the operational mechanism of the transformer. It also studies the effects of the width of the center leg and the position of the windings, which are very important design factors of the transformer. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 121(1):9–16, 1997