Wireless Power Transmitter Frequency Tuning for 15 mm Coil Gaps
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Solution Overview
Problem
Current wireless power transfer systems are limited to small separation gaps (3-5 mm) due to near-field operation, restricting their use in applications with thicker materials or devices with obstructions, and lack granular power control, which is necessary for commercial applications requiring extended distances and specific power levels.
Innovation Solution
A wireless power transmitter designed to operate at frequencies between 87 kHz and 205 kHz, using a ferrite core shielding around the coil except at the top, allowing for increased separation gaps up to 15 mm and implementing a control system to dynamically adjust the operating frequency for granular power control, eliminating the need for internal voltage regulation and enhancing compatibility with off-the-shelf power supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the separation gap between transmitter and receiver coils is increased beyond 3-5 mm, then the range of commercial applications is expanded, but the power transfer efficiency and thermal performance deteriorate
Solution Approach 1:
The patent changes the operating frequency parameter from the standard 6.78 MHz to an extended range of 87 kHz to 205 kHz. This frequency parameter change enables the system to maintain effective power transfer at increased separation gaps (up to 15 mm or more) while preserving thermal performance and efficiency characteristics that would otherwise deteriorate at larger distances.
2Length of stationary object
If the operating frequency is changed from 6.78 MHz to 87-205 kHz, then the separation gap is increased to 15 mm or greater, but the device complexity increases due to additional control systems
Solution Approach 1:
The patent implements a dynamic control system that adjusts the operating frequency within the 87 kHz to 205 kHz range based on real-time power level requirements and separation gap conditions. This dynamic frequency adjustment capability allows the system to maintain optimal performance across varying operating conditions while managing the complexity through adaptive control rather than fixed multi-frequency hardware.
3Ease of manufacture
If internal voltage regulation is eliminated to reduce costs, then compatibility with off-the-shelf power supplies is enhanced, but the loss of information regarding power control capability occurs
Solution Approach 1:
The patent uses frequency modulation as an intermediary control mechanism to convey power level information between the transmitter and receiver. By encoding power control commands as frequency shift signals within the 87 kHz to 205 kHz range, the system maintains full power control capability without requiring internal voltage regulation circuitry, thus achieving cost reduction while preserving functionality through the frequency-based communication intermediary.
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 wireless power transfer over larger separation gaps while maintaining efficiency and thermal performance, expanding the range of commercial applications and reducing costs by utilizing external power supplies and eliminating the need for internal voltage regulation.
Implementation Method 1
shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil
Implementation Method 2
inductive wireless power transfer, which occurs when magnetic fields created by a transmitting element induce an electric field, and hence, an electric current, in a receiving element
Implementation Method 3
operable at an operating frequency of about 87 kHz to about 205 kHz
Data Source
AI summary
A power transmitter for wireless power transfer includes a control and communications unit configured to provide power control signals to control a power level of a power signal configured for transmission to a power receiver and including a pulse width modulation (PWM) signal generator for determining and selecting the operating frequency from the operating frequency range. The power transmitter further includes an inverter circuit configured to receive a direct current (DC) power and convert the input power to a power signal, coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including at least one layer, the coil defining, at least, a top face, and a shielding comprising a ferrite core and defining a cavity, the cavity configured such that the ferrite core substantially surrounds all but the top face of the coil.