Inductance Compensation in Multi-Strand Wireless Power Coils
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Solution Overview
Problem
In wireless power transfer systems for electric vehicles, inductance variations between strands in a multi-strand coil lead to current imbalances, reducing power transfer efficiency and increasing losses due to unequal mutual inductance between strands.
Innovation Solution
The implementation of inductance compensation techniques, such as using inductor circuits or transformers connected to specific strands, to equalize current flow between strands in a multi-strand coil, thereby reducing current differences and enhancing power transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multi-strand coil is used for wireless power transfer, then power transfer capability is improved, but current imbalance between strands occurs due to inductance variations
Solution Approach 1:
The patent applies local quality by connecting inductor circuits or transformers to specific strands based on their individual inductance characteristics. Each strand receives customized compensation rather than uniform treatment, with the inductor circuit parameters tailored to the specific inductance variation of each strand to achieve current balance across all strands.
Solution Approach 2:
The patent changes the inductance parameter of specific strands by adding inductor circuits or transformers to compensate for inductance variations. By adjusting the inductance parameter of individual strands, the system achieves current balance while maintaining the multi-strand configuration's power transfer capability.
2Reliability
If inductance compensation is applied to equalize currents, then current balance is improved, but device complexity increases due to additional inductor circuits or transformers
Solution Approach 1:
The patent segments the compensation function by applying inductor circuits or transformers to only those strands that require compensation, rather than adding components to all strands. This segmented approach reduces overall device complexity while achieving current balance where needed.
Solution Approach 2:
The inductor circuits and transformers act as intermediary components that mediate between the power source and the coil strands. These intermediaries provide the necessary inductance compensation without requiring fundamental changes to the multi-strand coil structure, thus limiting the increase in device complexity.
3Loss of energy
If inductance compensation is implemented, then power transfer efficiency is improved, but loss reduction may be limited due to high mutual inductance between strands
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for inductance variations before power transfer occurs. The inductor circuits and transformers are configured to counteract the adverse effects of mutual inductance and self-inductance variations in advance, reducing current imbalance and improving power transfer efficiency before the actual power transfer process begins.
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 inductance compensation techniques effectively balance currents across strands, improving power transfer efficiency and reducing losses in wireless charging systems for electric vehicles.
Implementation Method 1
an inductor circuit connected to the first strand and disconnected from the second strand. The inductor circuit is further configured to reduce a current difference between a first current flowing through the first strand and a second current flowing through the second strand
Implementation Method 2
a first transformer connected to the first strand and a second transformer connected to the second strand. The first transformer is disconnected from the second strand and the second transformer is disconnected from the first strand. The first transformer and the second transformer are configured to collectively reduce a current difference
Data Source
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AI summary
This disclosure provides systems, methods and apparatus for wireless power transfer. In one aspect an apparatus for wirelessly transferring power from a charging power source to a device is provided. The apparatus includes a first strand wound in one or more turns and operationally coupled to the charging power source and a second strand wound together with the first strand in one or more turns and operationally coupled to the charging power source. The apparatus further includes an inductor circuit connected to the first strand and disconnected from the second strand. The inductor circuit is further configured to reduce a current difference between a first current flowing through the first strand and a second current flowing through the second strand.