Multi-Layer Coil Module for Wireless Power Transmission
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Solution Overview
Problem
Wireless charging technologies face inefficiencies due to increased parasitic capacitance and circulating currents when increasing the number of turns in coils, leading to reduced charging efficiency and uneven voltage distribution across coils.
Innovation Solution
A coil module design featuring multiple coils wound in a planar manner with strategically placed capacitances to maintain constant cross-sectional area, minimize voltage differences, and resonate at the operating frequency, reducing parasitic currents and enhancing coupling inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of turns of the coil is increased to increase coupling inductance, then the coupling inductance M increases, but the area of the coil increases and the charging efficiency decreases
Solution Approach 1:
The patent divides a single coil with many turns into multiple coils with fewer turns each, connecting them in series. This segmentation maintains the total number of turns (and thus coupling inductance) while reducing the area of each individual coil, preventing the degradation of charging efficiency due to increased relative area mismatch.
Solution Approach 2:
The patent transitions from a single-plane coil structure to a multi-layer stacked coil structure. By arranging coils in multiple layers (first layer, second layer, etc.) with corresponding capacitances, it achieves the same inductance enhancement effect in the vertical dimension rather than expanding in the horizontal plane, thus maintaining better area matching with the receiving coil.
2Reliability
If the number of turns of the coil is increased to increase coupling inductance, then the coupling inductance M increases, but the parasitic capacitance increases causing circulating current
Solution Approach 1:
The patent introduces corresponding capacitances as intermediary elements connected between adjacent coils in different layers. These capacitances act as mediators that balance the voltage distribution and provide a controlled path for displacement current, thereby suppressing the harmful circulating currents that would otherwise be generated by parasitic capacitance in the multi-turn coil structure.
Solution Approach 2:
The patent changes the electrical parameters of the coil system by introducing external capacitances with specific values. These capacitances are designed to resonate with the coil inductance at the operating frequency, transforming the harmful parasitic capacitance effect into a useful resonance effect that enhances coupling while suppressing circulating currents.
3Reliability
If the number of turns of the coil is increased to increase coupling inductance, then the coupling inductance M increases, but the voltage distribution becomes uneven
Solution Approach 1:
The patent segments the total inductance requirement into multiple smaller coil units, each with fewer turns. This segmentation distributes the voltage stress across multiple components rather than concentrating it in a single high-turn coil, leading to more uniform voltage distribution and improved electrical stability across the coil assembly.
Solution Approach 2:
The corresponding capacitances serve as voltage-balancing intermediaries between adjacent coils. They equalize the potential differences across different coil segments, ensuring uniform voltage distribution throughout the series-connected coil structure and preventing localized voltage spikes that would compromise system stability.
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 effectively increases coupling inductance, reduces reactive power loss, and improves charging efficiency while maintaining a constant coil area, ensuring consistent voltage distribution and minimizing circulating currents.
Implementation Method 1
The wireless power transmitting terminal converts a direct current voltage into an alternating current that generates an alternating magnetic field through the coil in the wireless power transmitting terminal
Implementation Method 2
The wireless power receiving terminal couples to the alternating magnetic field to induce a corresponding alternating voltage
Implementation Method 3
resonate at the operating frequency, reducing parasitic currents and enhancing coupling inductance
Data Source
AI summary
The present application discloses a coil module, a wireless power transmitting circuit and a wireless power receiving circuit. By overlapping a plurality of coils with each other and arranging matched capacitance between adjacent coils and matched capacitance at the output of the coil module, the coupling inductance is increased, the circulating current caused by parasitic capacitance between overlapped coils is effectively reduced and charging efficiency is improved while the cross-sectional area of the coil is kept constant.