Dual-Coil Wireless Power Transmitter with Nested LF-CF Filter
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Solution Overview
Problem
Current wireless power transfer technologies face inefficiencies when trying to operate at multiple frequency standards, such as A4WP, WPC, and PMA, due to significant frequency differences, which require separate coils and are not practical for portable devices with size constraints, and existing solutions either compromise efficiency or are not feasible for multi-receiver scenarios.
Innovation Solution
A wireless power transmitting device with two coils, each dedicatedly driven for separate frequencies, using an LF-CF filter to suppress eddy currents and maintain high impedance, allowing concurrent operation across multiple frequency bands with minimal loss and efficient power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil is used to operate at two separate frequencies, then device complexity is reduced, but transmission efficiency deteriorates significantly
Solution Approach 1:
The transmitter is divided into two separate coils: a first coil optimized for the first frequency band and a second coil optimized for the second frequency band. Each coil is independently controlled by its own controller, allowing optimal performance at respective frequencies without the efficiency losses associated with single-coil multi-frequency operation.
2Loss of energy
If coils are optimized for different frequencies, then transmission efficiency is improved, but device complexity increases
Solution Approach 1:
The first coil and second coil are arranged in a nested configuration where one coil is positioned within or adjacent to the other. This nesting approach allows both coils to coexist in a compact space, minimizing the increase in device footprint while enabling separate optimization for different frequency bands.
3Adaptability or versatility
If frequency separation is substantial (e.g., 6.78 MHz and 200 kHz), then multi-standard compatibility is improved, but coil optimization becomes difficult
Solution Approach 1:
By segmenting the transmitter into frequency-specific coils, each coil can be independently designed and optimized for its target frequency band. The first coil is optimized for the first frequency (e.g., 6.78 MHz for A4WP) while the second coil is optimized for the second frequency (e.g., 200 kHz for WPC/PMA), allowing precise tuning of inductance, capacitance, and physical dimensions for maximum efficiency at each frequency without compromise.
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
Enables simultaneous high-efficiency power transfer to devices operating at different frequency standards, maintaining efficiency and practicality even when frequency separation is substantial, such as between 6.78 MHz and 200 kHz, with minimal impact on device size and complexity.
Implementation Method 1
A controller causes the current or voltage drivers to selectively or concurrently generate an AC magnetic field at either of the frequencies or both frequencies concurrently
Implementation Method 2
The suppression of eddy currents uses a high impedance to the higher frequency. The high impedance suppresses eddy currents of the higher one of the two frequencies in a path of a lower one of the two frequencies
Data Source
AI summary
A method and device for wireless power transfer provide the ability for concurrent power transfer on two widely separated bands. A wireless power transmitting device includes two coils respectively configured for transmission at two separate wireless power transmission frequencies. A dedicated current or voltage driver is provided for each of said two coils. A controller causes the current or voltage drivers to selectively or concurrently generate an AC magnetic field at either of the frequencies or both frequencies. A method includes concurrently driving two coils arranged with respect to each other to reduce losses at two separate wireless power transmission frequencies while suppressing eddy currents in the path of one of the two coils.