Current balance method of dual windings parallel coils based on distributed capacitor compensation in high‐power WPT systems

Abstract

Dual windings parallel (DWP) coils are often used in high-power wireless charging applications to reduce current stress and internal resistance. Due to the inconsistent selfinductance and strong coupling of the two windings, the advantages of the DWP coils cannot be fully utilized. In particular, the current stresses of the two windings are different, which will cause one of the stress to exceed the limit, and the temperature rise is too high. The reason for the current imbalance in the two windings is analysed in this work, and a distributed capacitor compensation method is proposed to balance the current stress in the two windings. Finally, a WPT system with the DWP transmitting coil was built as an example to demonstrate the effectiveness of the proposed method. The experimental results show that the current ratio in two windings decreased from 1.70 to 1.05 after using the proposed compensation method.

Investigation of current balance methodologies for inductive power transfer coupler with multiple branches

“…The quality factor is up to 126. For IPT converters with high-quality factor, the winding resistance is commonly ignored when analyzing the output characteristics, which is a widely-used analysis method in the literature [24,34]. We ignore the resistance here to simplify the model.…”

“…In [23], it is proposed to link capacitors for each branch but still fails to achieve good current sharing accuracy. As for compensation methods, [24] designed compensation elements for each winding, respectively, and analyzed the influence of coil self‐inductance and compensation capacitor parameter drift on current balance. The compensation components in these papers are responsible for both current balancing and reactive power compensation, leading to limited current balance performance.…”

Litz wire loss performance and optimization for cryogenic windings

“…Litz wires are multi-filament wires composed of very fine, insulated and twisted conductors (strands). Traditionally, litz wire windings are used in medium and high-frequency inductors and transformers [1,2] to reduce the skin effect and proximity losses due to the leakage fields. Litz wire technology has also been considered to replace the stranded coils in stator windings in electrical machines [3] with both slotted and air-cored layouts where litz wires are exposed to high magnetic fields.…”