Wireless Charging Receiver Coil Layout for Lower DC Loss
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Solution Overview
Problem
Existing wireless charging receivers, particularly those adhering to the Qi v2.0 standard, face high direct current (DC) losses due to the high DC resistance of the charging coil, which is exacerbated by the coil windings being close to the outer edge, leading to increased alternating current (AC) resistance. This results in inefficiencies at higher power levels, such as 32 Watts, and poses a challenge in maintaining a sleek form factor without increasing the overall height of the charging coil.
Innovation Solution
The integration of an additional coil within an annular recess formed in a nanocrystalline sheet, allowing for additional winding turns without increasing the overall height, by positioning the first coil within the recess and electrically connecting it to a second coil, thereby reducing DC losses without expanding the width or height of the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If additional winding turns are added to reduce DC losses, then efficiency improves, but the overall height of the charging coil increases
Solution Approach 1:
The patent transitions from a single-layer coil configuration to a multi-layer stacked coil configuration. By arranging coils in the vertical dimension (stacking multiple coil layers), the design achieves additional winding turns without increasing the horizontal footprint, thereby reducing DC losses while maintaining a compact overall height profile.
Solution Approach 2:
The patent implements nested coil structures where inner coils are positioned within the bore of outer coils. This nesting arrangement allows multiple winding turns to be packed into a compact volume, achieving reduced DC resistance without proportionally increasing the external dimensions or overall height of the charging assembly.
2Area of stationary object
If coil windings are positioned close to the outer edge, then the form factor is maintained, but AC resistance increases
Solution Approach 1:
The patent applies different winding densities and configurations to different radial zones of the coil assembly. Inner regions utilize tighter winding densities while outer regions maintain larger spacing, optimizing the balance between maintaining a compact form factor and minimizing AC resistance effects such as skin effect and proximity effect.
Solution Approach 2:
The coil assembly is segmented into multiple discrete coil layers with different winding characteristics. Each segment can be optimized independently for its specific radial position, allowing the inner coils to address AC resistance concerns while outer coils maintain the compact form factor, thereby resolving the contradiction between size and electrical performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces DC losses and AC resistance on the last turn of the coil, enhancing efficiency without compromising the form factor or adhering to the Qi v2.0 standard, thus improving power transfer capabilities while maintaining a compact design.
Implementation Method 1
The first coil is aligned with the second coil, and the two coils are electrically connected together
Implementation Method 2
a nanocrystalline sheet (e.g., a magnetic shield)
Data Source
AI summary
A wireless charging receiver that includes a first coil, a second coil, and a nanocrystalline sheet is disclosed. The first coil is configured to be located within a recess in the nanocrystalline sheet and is positioned between the second coil and the nanocrystalline sheet. The first coil includes first and second terminals and the second coil includes third and fourth terminals. The first terminal is connected to the third terminal and the second terminal is connected to the fourth terminal to electrically connect the first coil to the second coil. The first coil may be formed of a flexible printed circuit board having a continuous trace or may be formed of litz wire. The first coil may be a hybrid coil with a first portion formed of a flexible printed circuit board having a continuous trace and with a second portion formed of litz wire.