Resonant Cell Wireless Power Mat Stray Field Reduction
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Solution Overview
Problem
Inductive charging pads face inefficiencies due to the rapid reduction of magnetic fields with distance, leading to the need for complex or expensive solutions to target the magnetic field effectively and charge multiple devices simultaneously while minimizing stray fields and ensuring compliance with electromagnetic regulations.
Innovation Solution
The use of multiple windings configured in series or parallel with capacitors that resonate to passively direct the magnetic field to the receiver's location, reducing stray fields and increasing efficiency by altering impedance and inductance based on proximity, and alternating magnetic polarization to contain the field within a smaller space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple coils are placed in zones in the mat with individual switches controlling each coil, then the magnetic field can be targeted to the receiver location, but the device complexity and cost increase due to the amount of multiple switches needed
Solution Approach 1:
The charging mat is divided into multiple resonant cells, each capable of being independently activated. This segmentation allows the magnetic field to be targeted to specific zones without requiring individual switches for each coil, as the resonant cells can be selectively excited through the shared transmitter coil.
Solution Approach 2:
The single transmitter coil serves multiple functions by coupling with different resonant cells depending on where the receiver is placed. Instead of requiring separate control circuits for each coil, the universal transmitter coil can excite any of the resonant cells that are positioned near the receiver, reducing overall system complexity.
2Adaptability or versatility
If a resonant coil is used to flood the whole mat with magnetic field, then power can be delivered to receivers placed anywhere in the mat, but power loss increases due to increased magnetic field interaction with conductive or magnetic objects
Solution Approach 1:
Instead of flooding the entire mat with magnetic field, the system creates localized magnetic fields only in the regions where receivers are actually placed. The resonant cells near the receiver are selectively activated, concentrating the magnetic field energy where needed and minimizing interaction with other conductive objects in the room.
Solution Approach 2:
The system dynamically adjusts which resonant cells are activated based on the receiver's position. As the receiver moves across the mat, different combinations of resonant cells are excited, allowing the magnetic field to follow the receiver and maintain efficient power transfer without continuously flooding the entire space.
3Loss of energy
If multiple resonant cells are used to target the magnetic field, then efficiency increases and stray fields are reduced, but the manufacturing complexity increases
Solution Approach 1:
Multiple resonant cells are merged into a single integrated charging mat structure, sharing common components such as the transmitter coil and control circuitry. This combining approach maintains the efficiency benefits of multiple targeted resonant cells while reducing manufacturing complexity compared to implementing separate independent charging systems for each zone.
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 localized power delivery to multiple devices, reducing power loss and compliance risks by dynamically adjusting the magnetic field to the receiver's position, enhancing charging efficiency and reducing the magnetic field's impact on surrounding objects.
Implementation Method 1
The use of multiple windings configured in series or parallel with capacitors that resonate to passively direct the magnetic field to the receiver's location
Implementation Method 2
inductive charging pads... relies on the magnetic field... The magnetic field must return back as a loop
Implementation Method 3
alternating magnetic polarization between the cells... This creates a coupling from cell to cell... but it produces a benefit that the magnetic field will diminish sooner with distance from the mat
Data Source
AI summary
A method of configuring windings in an inductive charging pad array by using capacitors for impedance control and configuring windings to reduce the stray magnetic fields produced.