Wireless Charging Converter Segmentation for EMC Reduction
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Solution Overview
Problem
Existing wireless charging systems for electric vehicles are costly due to the use of expensive litz wires for high-frequency power transmission, which also lead to electromagnetic interference and reduced electromagnetic compatibility (EMC).
Innovation Solution
A wireless charging system with an AC-to-DC converter and a DC-to-AC converter distributed between two housings, using ordinary DC cables for interconnection and flat inductive coils arranged parallel to each other, reducing the length of electrical connections and minimizing AC current transmission distance to minimize electromagnetic interference, and incorporating controllers for synchronized power transfer control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If litz wires are used for high-frequency power transmission in wireless charging systems, then power transfer efficiency is improved, but system cost increases and electromagnetic interference worsens
Solution Approach 1:
The patent divides the power conversion system into two separate housing units: a first housing containing the AC-to-DC converter and a second housing containing the DC-to-AC converter and inductive coil. This segmentation allows the high-frequency AC current generation to be localized near the coil while the AC-to-DC conversion can be positioned remotely, reducing the length of litz wire needed and thereby reducing electromagnetic interference while maintaining power transfer efficiency.
Solution Approach 2:
The patent extracts the AC-to-DC converter from the second housing and places it in a separate first housing. This extraction removes the source of high-frequency electromagnetic interference from the vicinity of the inductive coil and vehicle, reducing electromagnetic interference while the converter remains connected via DC cable to maintain power transfer efficiency.
2Loss of energy
If litz wires are used for high-frequency power transmission, then power transfer efficiency is improved, but system cost increases
Solution Approach 1:
By segmenting the system into two housings with DC cable interconnection, the patent eliminates the need for long litz wire runs, reducing material costs while maintaining the high-frequency power transmission capability needed for efficient wireless charging.
Solution Approach 2:
The patent replaces expensive litz wires with ordinary DC cables for the interconnection between housings. While litz wires are needed locally for high-frequency coil connection, the long-distance power transmission uses cheaper DC cables, significantly reducing overall system cost while maintaining efficiency through optimized local connections.
3Device complexity
If AC-to-AC conversion is performed in a single housing, then device complexity is reduced, but electromagnetic interference increases
Solution Approach 1:
The patent segments the converter system into two separate housings: the first housing contains the AC-to-DC converter and the second housing contains the DC-to-AC converter and inductive coil. This segmentation physically separates the high-frequency AC current generation from the power input stage, reducing electromagnetic interference while the modular design actually simplifies installation and maintenance despite increased component distribution.
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
The system achieves efficient power transfer with reduced electromagnetic interference, increased EMC, and flexible power control, enabling energy transmission with efficiency up to 95% while being more economical than previous solutions.
Implementation Method 1
a first inductive coil interconnected with the DC-to-AC converter and for inductively coupling to a second inductive coil for power transfer via an air gap
Implementation Method 2
an AC-to-DC converter connectable to an electric AC grid
Implementation Method 3
a DC-to-AC converter interconnected with the AC-to-DC converter
Data Source
AI summary
A wireless charging system for electric vehicles includes an AC-to-DC converter connectable to an electric AC grid; a DC-to-AC converter interconnected with the AC-to-DC converter; a first inductive coil interconnected with the DC-to-AC converter and for inductively coupling to a second inductive coil for power transfer via an air gap; a first housing, in which the AC-to-DC converter is arranged; a second housing, in which the DC-to-AC converter and the inductive coil are arranged; and a cable for interconnecting the AC-to-DC converter and the DC-to-AC converter outside of the first housing and second housing.