Chip-Scale Wireless Power Transfer via Three-Coil Resonance
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Solution Overview
Problem
The effective range of inductive wireless power transfer for chip-scale apparatuses is limited by the miniature size of the coils, with power transfer efficacy diminishing to practically nothing beyond five diameters, even with high Q coils and magnetic resonance enhanced designs, and is susceptible to misalignment and scalability issues in the RF spectrum.
Innovation Solution
A three-coil inductive wireless power transfer system is implemented, where a source coil is coupled with an intermediate coil and a load coil, with capacitors tuning out self-inductances to resonate at the same frequency, enhancing power transfer efficiency over distances several times the coil diameter, and a range extender configuration further extends this capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil is used for wireless power transfer, then the device structure is simple, but the power transfer efficacy diminishes to practically nothing beyond five diameters
Solution Approach 1:
The patent divides the single coil system into multiple coils (first coil, second coil, and third coil) arranged in sequence. The first coil receives power from the power source, the second coil acts as an intermediate transfer coil, and the third coil delivers power to the load. This segmentation enables power transfer over distances exceeding five diameters by creating multiple overlapping magnetic field zones, resolving the contradiction between structural simplicity and effective power transfer range.
2Volume of moving object
If coil size is reduced for chip-scale apparatus, then the device is miniaturized, but the effective range of power transfer is limited
Solution Approach 1:
The patent extends the power transfer system from a single-plane configuration to a multi-dimensional arrangement by positioning coils at different spatial locations (first coil at initial position, second coil at intermediate position, third coil at final position). This dimensional expansion allows the system to achieve extended power transfer range while maintaining miniaturized coil sizes suitable for chip-scale apparatus, overcoming the limitation where reduced coil size restricts effective range.
3Device complexity
If conventional two-coil system is used, then the system is simple to implement, but it is susceptible to misalignment and scalability issues
Solution Approach 1:
The patent introduces a second intermediate coil between the first and third coils to act as a mediator in the power transfer process. This intermediate coil compensates for misalignment between the first and third coils by providing an additional coupling path. The system can tolerate greater misalignment because the magnetic flux can route through the second coil, resolving the contradiction between simple system configuration and misalignment tolerance.
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 three-coil system achieves significant power transfer efficiency and communication over distances up to 30 times the coil diameter, with improved misalignment tolerance and scalability across various RF bands, enabling efficient powering of chip-scale devices.
Implementation Method 1
a source coil coupled to a power source such that current flows through the source coil when the source coil is excited by the power source... the source coil is to inductively power the intermediate coil, which is to inductively power a load coil
Implementation Method 2
capacitors tuning out self-inductances to resonate at the same frequency, enhancing power transfer efficiency
Data Source
AI summary
An inductive wireless power transfer apparatus includes a source coil coupled to a power source such that current flows through the source coil when the source coil is excited by the power source. The apparatus further includes a first capacitor coupled in series to the source coil. The apparatus further includes an intermediate coil surrounding the source coil and positioned within an identical plane as the source coil, and a second capacitor coupled in series to the intermediate coil. The capacitances of the first capacitor and the second capacitor are set to tune out self-inductances of the source coil and the intermediate coil. In embodiments, the source coil is to inductively power the intermediate coil, which is to inductively power a load coil positioned a distance away from the intermediate coil.