There has been an increasing demand for downsizing and upgrading electrical and electronic appliances ranging from consumer products to service machinery. As one approach to materialization, inverter-controllers and switching power supplies are advancing toward higher-frequency operation. In regard to coil wire intended to reduce the HF resistance induced by the skin effect, those units have applied Litz wire comprised of stranded enamelled wires or tape-insulated copper foil or copper sheet. The Litz wire has weak points of workability for winding and a low-space factor. Likewise, copper foil or copper sheet produces considerable heat due to eddy current loss and also difficulty in its edge insulation treatment. The authors have developed a high-frequency-compatible wire which makes use of a remarkable combination of Litz wire and copper foil or sheet. Upon close analysis, a parallel array wire strip comprised of multiple wires arranged in tape form has been developed. This paper discusses the general characteristics and some sample applications.
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