Split Resonant Capacitor Layout for Lower-Loss Wireless Charging
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Solution Overview
Problem
Existing wireless charging systems suffer from significant eddy current losses, which reduce efficiency, particularly in configurations where capacitors and coils are arranged in parallel series, leading to inefficiencies up to 30% loss in power transfer.
Innovation Solution
Implementing a split resonant capacitor configuration where capacitors and wireless charging coils are arranged in parallel series pairs, with a common input and output node, reducing eddy currents and improving AC current sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single resonant capacitor configuration is used in wireless charging, then the device structure is simple, but eddy current losses are high and charging efficiency is reduced
Solution Approach 1:
The patent divides the single resonant capacitor into multiple segmented capacitors (e.g., C1, C2, C3, C4) arranged in a bridge configuration. Each capacitor segment is connected to its own coil, creating multiple independent resonant circuits that operate in parallel. This segmentation reduces eddy current losses by distributing the current flow across multiple paths, preventing concentrated eddy currents that occur in single-capacitor designs.
2Productivity
If multiple capacitor and coil series pairs are used in parallel, then eddy current losses are reduced and efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The patent employs an asymmetric bridge configuration where capacitors and coils are arranged in a non-uniform pattern optimized for current distribution. The bridge structure allows unequal current paths that balance the load across components, reducing eddy currents while maintaining manageable complexity. This asymmetric arrangement enables better control over current flow patterns compared to symmetric configurations.
Solution Approach 2:
The patent transitions from a single-plane capacitor-coil arrangement to a multi-dimensional bridge configuration. The capacitors are arranged in a bridge topology that adds a structural dimension, creating multiple nodes and paths in a two-dimensional plane. This dimensional reorganization allows current to flow through multiple independent paths simultaneously, reducing eddy current concentration while keeping the physical footprint manageable.
3Ease of manufacture
If all capacitors are in parallel with all coils in parallel, then the circuit is simple to implement, but eddy current losses are significant due to current concentration
Solution Approach 1:
The patent segments the parallel capacitor-coil configuration into series pairs (C1-L1, C2-L2, etc.) that are then arranged in a bridge structure. Each series pair forms an independent resonant circuit unit that is easier to manufacture as a module, while the bridge connection of these modules prevents the current concentration problems of pure parallel arrangements.
Solution Approach 2:
Instead of connecting all capacitors in parallel with all coils in parallel, the patent inverts the approach by first creating series capacitor-coil pairs, then connecting these pairs in a bridge configuration. This inversion of the connection hierarchy fundamentally changes the current flow patterns, distributing current through multiple series paths rather than allowing direct parallel current concentration.
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
The split resonant capacitor configuration significantly reduces eddy current losses, enhancing wireless charging efficiency by equalizing current flow through each pair, thereby improving power transfer efficiency.
Implementation Method 1
one or more coils that transduce energy between magnetic fields and alternating current (AC) power signals
Implementation Method 2
resonant tank that includes one or more resonant capacitors and one or more coils
Data Source
AI summary
An example device includes a plurality of capacitor and wireless charging coil series pairs that are collectively in parallel; and one or both of: a driver circuit configured to drive the plurality of capacitor and wireless charging coil series pairs with a first common signal; or a sink circuit configured to receive a second common signal from the plurality of capacitor and wireless charging coil series pairs.