A Misalignment Tolerant Winding Pattern with AC Resistance Reduction
Capability for Inductive Power Transfer Application
Abstract
Litz wire planar coils are widely used in inductive power transfer
systems due to the low profile and high efficiency in medium frequency
operation. In high frequency region, the ac resistance of litz wire
planar coils increases significantly, which leads to efficiency-drop and
temperature-rise problems. Meanwhile, misalignment occurs during the
daily operation and causes unstable power supply. In this work, we
propose a novel winding pattern for reducing the ac resistance, thermal
stress and misalignment sensitivity. From experimental result, the
proposed winding pattern reduces the ac resistance maximally by
78\% at 1 MHz, and 263\% at 20 MHz
compared with the conventional winding pattern under the same geometry
and wire length. The total efficiency is improved by 2\%
and misalignment tolerance is maximally improved by 46\%
in terms of the output power, and 5\% in terms of the
efficiency with the proposed winding pattern.