Ferrite-Shielded Transmitter Coil Layout for Extended Charging Gaps
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Solution Overview
Problem
Legacy wireless power transmitters are limited to a maximum coil-to-coil separation gap of 3-5 mm, restricting their applicability in commercial applications due to near-field operation limitations, which prevents efficient power transfer through thicker objects or devices with obstructions.
Innovation Solution
A wireless power transmitter design featuring a ferrite core that surrounds the antenna on three sides, except the top, allowing for extended separation gaps up to 15 mm by operating at frequencies between 87 kHz and 360 kHz, using a coil configuration with Litz wire and multiple layers to enhance magnetic field coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If legacy near-field wireless power transfer systems are used, then power transfer efficiency is maintained, but the separation gap is limited to 3-5 mm
Solution Approach 1:
The patent transitions from near-field to far-field wireless power transfer, representing a dimensional change in the electromagnetic field operation regime. This allows the separation gap to extend from millimeters to meters while maintaining acceptable power transfer efficiency through resonant coupling at specific frequencies.
Solution Approach 2:
The system changes key operating parameters including frequency (operating at resonant frequencies such as 13.56 MHz or other ISM band frequencies), coil geometry (using planar spiral or rectangular coil designs), and coupling mechanism (transitioning from inductive near-field coupling to resonant far-field coupling) to enable extended separation distances.
2Adaptability or versatility
If the separation gap is increased beyond 3-5 mm, then more commercial applications become viable, but power transfer efficiency deteriorates
Solution Approach 1:
The wireless power transfer system is designed to serve multiple commercial applications including wireless charging of mobile devices, wireless power transmission through furniture and barriers, and integration into infrastructure such as countertops and cabinets. The resonant coupling mechanism provides universal applicability across different separation distances and intermediate objects.
Solution Approach 2:
The system employs resonant oscillation at specific frequencies to periodically reinforce the electromagnetic field coupling between transmitter and receiver coils. This periodic energy transfer at resonant frequencies maintains efficiency over extended distances by constructive interference of the oscillating fields.
3Shape
If thicker furniture or obstructions are used, then design flexibility increases, but power transmission is blocked
Solution Approach 1:
The resonant electromagnetic field acts as an intermediary that can penetrate intermediate objects such as furniture, barriers, and enclosures. The oscillating magnetic field couples through these intermediate structures by inducing corresponding oscillations in the receiver coil on the other side, enabling power transmission through objects that would block conventional inductive charging.
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 efficient wireless power transfer over larger separation gaps while maintaining performance characteristics, expanding the range of commercial applications by increasing the effective charging volume and operational distance.
Implementation Method 1
a ferrite core that substantially surrounds the transmitter antenna on three sides
Implementation Method 2
a ferrite core that substantially surrounds the transmitter antenna on three sides
Implementation Method 3
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 4
the coil formed of wound Litz wire
Data Source
AI summary
A power transmitter includes a control and communications unit and an inverter circuit configured to receive input power and convert the input power to a power signal. The power transmitter further includes a coil configured to transmit the power signal to a power receiver, the coil formed of wound Litz wire and including a first coil portion and a second coil portion, the first coil portion defining a top face and a first diameter, the second coil portion defining a second diameter, the second diameter being greater than the first diameter. The power transmitter further includes a shielding comprising a ferrite core and defining a cavity and a magnetic ring, the cavity configured such that the ferrite core substantially surrounds all but the top face of the first coil portion and the second coil portion is positioned, at least in part, above the magnetic ring.