Contactless Power Transmission Using Constant High-Frequency Current
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Solution Overview
Problem
Existing contactless power transmission systems face challenges in supplying power effectively to loads when the specifications and coupling coefficients of power transmission and reception units differ, leading to inefficiencies and potential breakdowns due to uneven current distribution across diodes in rectifying circuits.
Innovation Solution
A contactless power transmission system that outputs a constant high-frequency current from the power source, making the power reception units act as constant current sources, allowing currents to be added together and supplied to the load regardless of the specifications and coupling coefficients of the units, using magnetic field resonance and resonance circuits to achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple power reception units with different specifications and coupling coefficients are used, then power supply adaptability is improved, but current distribution uniformity deteriorates
Solution Approach 1:
The patent changes the operating parameter from voltage to current, making the power reception units operate at a constant current mode. This allows units with different specifications and coupling coefficients to be connected in parallel without causing current distribution issues, as each unit naturally operates at its own current level determined by the constant current source characteristics.
2Power
If diodes are connected in parallel to distribute current, then current handling capacity is improved, but current balance deteriorates due to impedance variations
Solution Approach 1:
Instead of trying to force current balance through parallel diode connections (which fails due to impedance variations), the patent inverts the approach by using constant current sources that naturally operate independently. Each power reception unit becomes a constant current source, eliminating the need for current balancing while maintaining safe operating levels.
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
Enables reliable power supply to loads even when the specifications and coupling coefficients of the power transmission and reception units vary, preventing diode breakdowns and ensuring consistent current delivery, as demonstrated in charging systems for electric automobiles.
Implementation Method 1
power is transmitted contactlessly from a power transmission apparatus connected to a high-frequency power source device, to a power reception apparatus connected to a load. A power transmission coil is included in the power transmission apparatus, and a power reception coil is provided in the power reception apparatus. Contactless power transmission is performed due to the power transmission coil and the power reception coil being magnetically coupled.
Implementation Method 2
Japanese Patent No. 4293854 discloses a contactless power supply apparatus that includes multiple power reception units each including a resonance circuit composed of a power reception coil and a resonance capacitor
Data Source
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AI summary
A contactless power transmission system is provided for supplying power contactlessly from a power transmission apparatus to a power reception apparatus. The power transmission apparatus includes a high-frequency power source device for outputting a constant high-frequency current, and power transmission units having serial resonance circuits. The power reception apparatus includes power reception units having parallel resonance circuits. A power transmission coil of the power transmission unit and a power reception coil of the power reception unit are magnetically coupled. The power transmission units are connected in series, while the power reception units are connected in parallel. Power is transmitted from the power transmission unit to the power reception unit by magnetic field resonance.