Wireless Power Transfer Coil Reactance Adjustment for Resonance Control
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Solution Overview
Problem
Existing wireless power transfer systems using current control elements in series with power transmission coils are limited in versatility and can negatively impact the resonant characteristics of series-resonant power transmission circuits, leading to reduced power transmission efficiency and increased size requirements for saturable inductors.
Innovation Solution
A wireless power transfer apparatus utilizing a resonant power transmission circuit with a characteristic adjuster comprising a characteristic adjustment coil and capacitor, which adjusts the reactance of the power transmission coil to match or exceed a reference value based on magnetic coupling with a power receiving apparatus, thereby controlling current flow and reducing unnecessary power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current control elements are connected in series with power transmission coils, then current flow can be controlled, but the resonant characteristics of the power transmission circuit are negatively impacted and device size increases
Solution Approach 1:
The patent extracts the current control function from the series connection configuration and relocates it to a parallel connection configuration. The characteristic adjuster is connected in parallel with the power transmission coil rather than in series, which allows current control while preserving the resonant characteristics of the series-resonant power transmission circuit. This extraction resolves the contradiction by separating the control function from the resonant circuit path.
Solution Approach 2:
The characteristic adjuster acts as an intermediary element that modifies the impedance characteristics of the power transmission coil without directly interfering with the series resonant current path. By connecting the characteristic adjuster in parallel and using it to adjust reactance, the system achieves current control functionality while maintaining the integrity of the resonant circuit, thus resolving the contradiction between control capability and resonant performance.
2Ease of operation
If current control elements are connected in series with power transmission coils, then current flow can be controlled, but the size of saturable inductors increases
Solution Approach 1:
The patent extracts the current control function from the series connection configuration and relocates it to a parallel connection configuration. The characteristic adjuster is connected in parallel with the power transmission coil rather than in series, which allows current control while preserving the resonant characteristics of the series-resonant power transmission circuit. This extraction resolves the contradiction by separating the control function from the resonant circuit path.
Solution Approach 2:
The patent changes the connection parameter from series to parallel, and adjusts the reactance parameter of the power transmission coil through the characteristic adjuster. By modifying the reactance to be equal to or greater than a reference value, the system achieves current control functionality with reduced component size requirements, resolving the contradiction between control capability and component size.
3Loss of energy
If reactance of power transmission coil is adjusted to control current, then power transmission efficiency improves, but frequency matching becomes difficult
Solution Approach 1:
The patent introduces a dynamic adjustment mechanism through the characteristic adjuster that can modify the reactance of the power transmission coil based on operating conditions. This dynamic capability allows the system to optimize power transmission efficiency by adjusting current flow while automatically maintaining frequency matching, resolving the contradiction between efficiency optimization and frequency matching difficulty.
Solution Approach 2:
The patent changes the reactance parameter of the power transmission coil through the characteristic adjuster to achieve optimal current control and power transmission efficiency. By adjusting the reactance to be equal to or greater than a reference value, the system improves efficiency while the parallel connection configuration maintains frequency matching capability, resolving the contradiction between efficiency and ease of manufacture.
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 solution enhances the applicability of wireless power transfer systems by reducing unnecessary power consumption and leakage magnetic flux, improving power transfer efficiency, and eliminating the need for conventional current control elements connected in series.
Implementation Method 1
a characteristic adjuster (120) configured as a closed loop including a characteristic adjustment coil (122) magnetically coupled to the power transmission coil (112), and a characteristic adjustment capacitor (126) connected to the characteristic adjustment coil (122)
Implementation Method 2
a resonant power transmission circuit (110) including a power transmission coil (112) having a reactance, and a resonant capacitor (116) connected to the power transmission coil (112)
Data Source
AI summary
In a wireless power transfer apparatus, a characteristic adjuster has a frequency characteristic that causes, in a power transfer mode from at least one power transmission unit to a power receiving apparatus, a resonant power transmission circuit to have a resonance frequency that substantially matches an operating frequency. The reactance of a power transmission coil has a reference value in the power transfer mode. The frequency characteristic of the characteristic adjuster causes, in a power non-transfer mode from the at least one power transmission unit to the power receiving apparatus, a reactance of a power transmission coil to become an adjusted value that is higher than the reference value.