Selectable Coil Array for Wireless Power
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Solution Overview
Problem
Conventional inductive power supplies restrict spatial freedom due to alignment requirements between primary and secondary coils, leading to inefficiencies and limitations in power transfer, particularly with the use of single-layer coil arrays and mechanical alignment aids.
Innovation Solution
A multi-layer coil array system where coils can be selectively energized to shift the magnetic field across a charging surface, allowing power to be provided at any point, reducing losses from parasitic loads and increasing efficiency by optimizing coil combinations based on secondary coil position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single primary coil is used in conventional inductive power supplies, then the system structure is simple, but spatial freedom is restricted due to alignment requirements between primary and secondary coils
Solution Approach 1:
The single primary coil is segmented into multiple discrete coil elements arranged in an array. Each coil element can be independently controlled and energized. This segmentation allows the system to create magnetic fields at different locations across the charging surface, enabling devices to be charged at various positions without requiring precise alignment, thus resolving the contradiction between spatial freedom and device complexity.
2Ease of operation
If all coils in the array are driven simultaneously to create uniform magnetic flux, then spatial freedom is improved, but parasitic loads absorb magnetic field and lower system efficiency
Solution Approach 1:
The system dynamically selects and energizes only the specific coil elements needed based on the detected position of the secondary device. Rather than driving all coils simultaneously, the controller activates only those coils in the vicinity of the device, creating a localized magnetic field. This dynamic approach maintains device placement flexibility while minimizing energy losses to parasitic loads by reducing the overall magnetic field footprint.
Solution Approach 2:
The magnetic field is concentrated locally at the position where the secondary device is detected rather than being distributed uniformly across the entire charging surface. By energizing only the relevant coil elements near the device, the system creates a focused magnetic field that improves coupling efficiency and reduces energy absorption by parasitic loads in other areas, thus resolving the contradiction between spatial freedom and power transfer efficiency.
3Ease of operation
If a large primary coil is used to provide energy over a greater area, then spatial freedom is improved, but stray magnetic fields are created and power transfer efficiency decreases
Solution Approach 1:
The large primary coil is divided into multiple smaller coil elements arranged in an array. This segmentation allows the system to provide energy across a large charging surface area by selectively energizing different combinations of coil elements, while avoiding the creation of extensive stray magnetic fields that would result from a single large coil. Each small coil element generates a localized magnetic field, reducing overall stray field interference.
4Measurement precision
If mechanical alignment aids or magnetic alignment features are used, then alignment precision is improved, but device complexity and user freedom are reduced
Solution Approach 1:
The patent replaces mechanical alignment aids and magnetic alignment features with a selectable coil array system that uses electrical control to achieve alignment. Instead of using physical guides or magnetic attractors to force device placement, the system detects the device position and electronically activates the appropriate coil elements to create a magnetic field at the correct location. This substitution eliminates mechanical constraints while maintaining or improving alignment accuracy, resolving the contradiction between alignment precision and device placement freedom.
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 provides spatial freedom for device placement while maintaining efficient power transfer, reducing losses and enhancing coupling between coils, and dynamically adjusts the magnetic field to align with the secondary coil's position, improving overall system efficiency.
Implementation Method 1
An inverter 206 can switches the DC power at a frequency controlled by the controller 208 in order to generate an AC signal across the inductive tank circuit 210 to produce an electromagnetic field
Implementation Method 2
The AC signal can be rectified into DC power in a rectification circuit 216. From there, the DC power can directly power the load 220, or where the load is a battery the power can be used to charge the battery
Data Source
AI summary
An inductive wireless power system using an array of coils with the ability to dynamically select which coils are energized. The coil array can determine the position of and provide power to one or more portable electronic devices positioned on the charging surface. The coils in the array may be connected with series resonant capacitors so that regardless of the number of coils selected, the resonance point is generally maintained. The coil array can provide spatial freedom, decrease power delivered to parasitic loads, and increase power transfer efficiency to the portable electronic devices.