Inductive Power Supply With Segmented Field Generators
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Solution Overview
Problem
Existing wireless charging systems for portable devices face inefficiencies due to the generation of uniform magnetic fields, leading to power dissipation and heat buildup, as well as low coupling efficiency, when trying to allow devices to be placed anywhere on the charging pad without alignment.
Innovation Solution
The system employs a localized electromagnetic induction method using a power transfer surface with field generators that generate fields perpendicular to the surface, combined with sensing and switching mechanisms to activate specific field generators based on the position of the device's receiver coil, ensuring magnetic flux is directed only to the receiver, minimizing coupling with the rest of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a uniform magnetic field is generated across the full surface of the pad to allow freedom of placement, then devices can be charged anywhere on the pad, but this causes Eddy currents in metal parts leading to power dissipation and heat generation
Solution Approach 1:
The charging pad is divided into multiple independently controllable coil segments arranged in a grid pattern. Instead of activating the entire pad surface, only the specific coil segment beneath the device is activated, creating a localized magnetic field that avoids inducing Eddy currents in other metal parts of the device while maintaining freedom of placement capability
Solution Approach 2:
The magnetic field is concentrated locally at the position where the device is placed rather than being uniformly distributed across the entire pad surface. This localized field generation reduces unnecessary electromagnetic interactions with metal components away from the device, thereby minimizing power dissipation and heat generation while preserving the ability to charge devices anywhere on the pad
2Adaptability or versatility
If a uniform magnetic field is generated across the full surface of the pad, then devices can be placed anywhere without alignment, but this results in low coupling between the recharger and device coils and high losses
Solution Approach 1:
The pad surface is segmented into multiple discrete coil segments that can be independently activated. When a device is detected on the pad, the system activates only the specific segment(s) directly beneath the device, ensuring strong magnetic coupling and high transfer efficiency while maintaining the flexibility to charge devices at any position on the pad surface
Solution Approach 2:
The system dynamically identifies the position of the device on the pad and activates only the relevant coil segment(s) in response. This dynamic adaptation ensures optimal coupling efficiency regardless of where the device is placed, resolving the contradiction between freedom of placement and coupling reliability
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 approach allows for efficient and flexible placement of devices on the charging pad while reducing unwanted inductive heating and interference, maintaining high power transfer efficiency and minimizing energy loss.
Implementation Method 1
a system for transferring power from a primary unit to a secondary device, separable from the primary unit, by electromagnetic induction
Implementation Method 2
the field will couple to metal in the portable device; this sets up Eddy currents which results in losses and consequently power dissipation causing the device to heat up
Data Source
AI summary
There is disclosed an inductive power transfer system comprising a primary unit and a secondary device separable from the primary unit, the primary unit comprising a power transfer surface and more than two field generators each operable to generate an electromagnetic field, the field generators being located at different positions relative to the power transfer surface, the secondary device comprising a power receiver having a secondary coil, the system further comprising: determining means for determining at least one of the position and the orientation of the power receiver relative to the power transfer surface; and controlling means for controlling the field generators such that at least one first field generator and at least one second field generator, selected in dependence upon such determination, are active in a substantially opposite sense to one another so as to direct magnetic flux through the secondary coil thereby supplying power to the secondary device, and further such that a third one of the field generators is inactive so that fewer than all of the field generators are active simultaneously.