Active Canceling Coils for Dynamic Wireless Charging Shielding
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Solution Overview
Problem
High-power dynamic wireless charging systems face electromagnetic safety concerns due to strong electromagnetic fields, which existing passive shielding solutions like ferrite shielding are costly and inefficient, especially for in-motion charging applications where reduced infrastructure is needed.
Innovation Solution
The implementation of active electromagnetic shielding using canceling coils, which are offset from the power transmission coil and electrically connected to generate canceling currents out of phase with the transmit current to destructively interfere with the electromagnetic fields, reducing stray magnetic field emissions and improving safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive shielding solutions like ferrite shielding are used, then electromagnetic field emissions are reduced, but cost and infrastructure complexity increase
Solution Approach 1:
The patent applies active electromagnetic shielding by generating canceling electromagnetic fields that destructively interfere with the stray magnetic fields produced by the power transmission coil. Instead of passively blocking fields with ferrite materials, the system actively creates opposing fields using canceling coils driven by out-of-phase currents, thereby converting the harmful electromagnetic emissions into beneficial canceled fields that reduce overall emissions while avoiding the need for extensive passive shielding infrastructure
Solution Approach 2:
The system changes the phase parameter of the current driving the canceling coils to be out of phase with the transmit current, thereby altering the electromagnetic field characteristics to achieve destructive interference. This parameter change (phase shift) enables active cancellation of electromagnetic fields without requiring physical shielding materials, reducing infrastructure complexity while maintaining emission reduction effectiveness
2Object-affected harmful factors
If passive shielding solutions like ferrite shielding are used, then electromagnetic field emissions are reduced, but system cost increases
Solution Approach 1:
The patent replaces expensive passive ferrite shielding materials with active electromagnetic cancellation using coils and control circuitry. The system generates canceling fields that destructively interfere with stray magnetic fields, eliminating the need for large quantities of ferrite materials while achieving the same emission reduction goal at lower cost
Solution Approach 2:
The patent substitutes mechanical/passive ferrite shielding with an active electromagnetic field-based solution. Instead of using physical ferrite materials to block and absorb electromagnetic fields, the system uses canceling coils to generate opposing electromagnetic fields that actively cancel the harmful emissions, thereby replacing material-based shielding with field-based cancellation
3Productivity
If high power is used for dynamic wireless charging, then charging efficiency is improved, but electromagnetic safety concerns increase
Solution Approach 1:
The patent enables high-power dynamic wireless charging by implementing active electromagnetic shielding that generates canceling fields to destructively interfere with the strong electromagnetic fields produced during high-power transmission. This allows the system to operate at high power levels for efficient charging while simultaneously reducing stray magnetic field emissions to comply with safety standards, thereby converting the harmful high-field-strength issue into a manageable condition through active cancellation
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 minimizes electromagnetic field emissions to comply with safety standards, such as the 27 μT standard at 0.8 meters from the receive coil, while reducing the need for extensive infrastructure and maintaining high efficiency in wireless power transfer.
Implementation Method 1
deliver canceling currents to the first canceling coil and the second canceling coil to destructively interfere with portions of electromagnetic fields generated by the power transmission coil
Implementation Method 2
The power transmission coil is configured to inductively couple to and provide wireless power to receive coils of wirelessly chargeable vehicles
Data Source
AI summary
Active electromagnetic shielding for dynamic high power wireless charging and related electrified roadway systems, method, and wireless power transmitters is disclosed. A wireless power transmitter includes a first canceling coil offset from a power transmission coil, a second canceling coil offset from the power transmission coil, and circuitry electrically connected to the first canceling coil and the second canceling coil. The circuitry is configured to deliver canceling currents to the first canceling coil and the second canceling coil to destructively interfere with portions of electromagnetic fields generated by the power transmission coil.