A Motorized Air-Core Variable Inductance Winding Structure

Air-core windings, which are free from core losses and flux saturation, are widely used in power conversion applications such as wireless power transfer, resonance converters, and induction heating. They are typically paired with compensating capacitors to form resonant tanks handling ac currents. However, the component tolerances and the winding misalignment will cause discrepancies between the circuit’s optimal operating frequency and the designated frequency. Real-time adjustment of the inductance values in applications will resolve this problem. This paper introduces a motorized planar linkage structure that adjusts the winding’s equivalent aperture, allowing for continuous inductance adjustment. This adjustment can be made during operation with a feedback system controlling the inductance to maintain the optimal operating point. An example of a misaligned wireless power transfer system is introduced in this paper to demonstrate the benefit of the variable inductance air-core winding, achieving optimal performance.