Self-Oscillation Circuit Resonance Frequency Control
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Solution Overview
Problem
Conventional wireless power transmission systems face reliability issues due to the risk of unintended resonance points becoming operating points, leading to unpredictable characteristics and low reliability when trying to achieve high output power and efficiency.
Innovation Solution
A wireless power transmission apparatus with a power transmission coil, a power transmission-side resonant capacitor, and a self-oscillation circuit that forms a combined resonance circuit with a power reception-side resonance circuit, operating at the highest frequency among multiple resonance points to prevent unintended characteristics and ensure high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple resonance points are brought closer together to achieve high output power and high efficiency, then power transmission efficiency is improved, but reliability deteriorates due to the risk of unintended resonance points becoming operating points
Solution Approach 1:
The patent applies parameter changes by deliberately selecting and controlling the resonance frequency parameter. The self-oscillation circuit is designed to operate at a specific resonance frequency that is determined to be the highest among multiple resonance points. This frequency selection ensures optimal power transmission efficiency while preventing operation at unintended resonance points, thus resolving the contradiction between efficiency and reliability.
2Device complexity
If a single coil power transmission coil is used instead of two coils connected by feedback winding or center tap, then device complexity is reduced and cost is lowered, but achieving high output power and efficiency becomes more difficult
Solution Approach 1:
The patent utilizes resonance, which is a vibrational phenomenon, to achieve high output power with a single coil. By operating the self-oscillation circuit at the resonant frequency of the power transmission coil and resonant capacitor, the system achieves maximum power transfer and efficiency. The resonant oscillation amplifies the effective magnetic field strength, enabling high output power without requiring complex multi-coil structures.
Solution Approach 2:
The patent changes the operating parameter to resonance frequency, which enables a single coil configuration to achieve high output power. By tuning the self-oscillation circuit to operate at the resonant frequency determined by the power transmission coil and resonant capacitor, the system achieves optimal power transfer efficiency and high output power, eliminating the need for feedback windings or center taps.
3Loss of energy
If resonance points are brought closer together for high efficiency operation, then power transmission efficiency is improved, but characteristics become unpredictable depending on the operating point
Solution Approach 1:
The patent stabilizes system characteristics by fixing the operating parameter at a specifically determined resonance frequency. The self-oscillation circuit is designed to operate at the highest resonance frequency among multiple resonance points, which provides stable and predictable system characteristics. This frequency determination approach ensures consistent power transmission efficiency and reliable operation, eliminating the unpredictability associated with operating at arbitrary resonance points.
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 configuration allows for high reliability by ensuring operation at the highest resonance frequency, reducing loss and maintaining high efficiency while preventing unintended resonance points from becoming operating points, thus enabling a compact and reliable wireless power transmission system.
Implementation Method 1
combined resonance circuit formed by magnetic coupling of the power transmission-side resonance circuit with a power reception-side resonance circuit
Implementation Method 2
a self-oscillation circuit that converts a DC voltage to an AC voltage, and that supplies the AC voltage to the power transmission coil
Implementation Method 3
there is a state in which multiple resonance points exist in a combined resonance circuit
Data Source
AI summary
A wireless power transmission apparatus includes a power transmission coil that transmits electric power; a power transmission-side resonant capacitor that is connected to the power transmission coil and that, with the power transmission coil, forms a power transmission-side resonance circuit; and a self-oscillation circuit that converts a DC voltage to an AC voltage, and that supplies the AC voltage to the power transmission coil. The wireless power transmission apparatus has a state, during power transmission, in which multiple resonance points exist in a combined resonance circuit formed by magnetic coupling of the power transmission-side resonance circuit with a power reception-side resonance circuit formed from a power reception coil and a power reception-side resonant capacitor. In the state, the self-oscillation circuit operates at the highest frequency among the multiple resonance points.