Wireless Charging Coil Arrays for EMF Harmonic Suppression
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Solution Overview
Problem
Current wireless power transfer systems using magnetic induction face challenges in precisely controlling magnetic flux to ensure efficient power transfer while minimizing leakage into the environment, which can exceed human and electronic exposure limits.
Innovation Solution
A modular coil array system is implemented, where n×m arrays of coil assemblies are arranged in a rectilinear grid pattern, with each coil generating a charging signal out-of-phase with neighboring coils to achieve destructive interference, reducing additive magnetic flux density and confining it within an exclusion zone around the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnetic induction is used for wireless power transfer, then power transfer efficiency is improved, but magnetic flux leakage into the environment increases exceeding exposure limits
Solution Approach 1:
The patent divides the wireless power transfer system into multiple coil assemblies arranged in arrays, where each coil can be independently controlled. This segmentation allows precise management of magnetic flux from individual coils while maintaining overall power transfer efficiency.
Solution Approach 2:
The patent employs phase modulation of charging signals, adjusting the phase parameter of each coil assembly to achieve destructive interference of magnetic flux in the environment while constructive interference occurs at the vehicle receiving coils, thus controlling magnetic flux distribution through parameter changes.
2Productivity
If multiple coil assemblies are used to increase power transfer capability, then power transfer efficiency is improved, but control of magnetic flux distribution becomes more difficult
Solution Approach 1:
The patent implements dynamic control of phase and amplitude parameters for each coil assembly based on real-time operating conditions, allowing the system to adaptively optimize power transfer while managing magnetic flux distribution across multiple coils.
Solution Approach 2:
The patent uses feedback mechanisms to monitor and adjust the operation of multiple coil assemblies, enabling coordinated control that simplifies the management of complex multi-coil systems while maintaining optimal performance.
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 effectively reduces magnetic flux density outside the exclusion zone, ensuring compliance with exposure limits and enhancing power transfer efficiency by minimizing magnetic flux leakage into the environment.
Implementation Method 1
Wireless Power Transfer (WPT) makes use of magnetic induction in an air core transformer. Electrical power is sent from the sending apparatus to the receiving apparatus by means of magnetic flux linkage between the primary (transmitting) and secondary (receiving) coils as stated in Faraday's Law of magnetic induction.
Implementation Method 2
Each coil assembly generates a charging signal at a frequency that is out-of-phase with a charging signal of a neighboring coil assembly during a charging session whereby a charging signal transmitted by a coil assembly destructively interferes with a charging signal transmitted by the neighboring coil assembly to reduce additive magnetic flux density during charging
Data Source
AI summary
Modular coil assemblies for wireless charging of vehicles have coil geometries and communications designed to limit electromagnetic field (EMF) levels in regions where humans or other living objects may be present. The modular coil assemblies are designed with the ability to shape the magnetic field to be predominately within shielding provided by the auto chassis by, for example, providing side-by-side phase cancellation or diagonal versus front-to-back (for 1×3, 2×3 array configurations) phase cancellation. The power levels and frequency offset pairwise compensation of the respective coils may be controlled to improve suppression of both the fundamental and harmonic signals and thus to reduce magnetic field exposure potential. The phase cancellation of the magnetic flux density from respective coil assemblies varies over a range to provide, for example, ˜50% suppression at 125° offset and up to ˜100% suppression at 180°. Charging profiles for vehicles and charging stations may be used to maximize the magnetic flux density suppression during charging.