DC-DC Converter Input Impedance Stabilization for Magnetic Resonance Power Feeding
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Solution Overview
Problem
In magnetic resonance-based power feeding systems, the dynamic change in input impedance of the power receiving device due to varying battery charge conditions leads to impedance mismatch and reduced power feeding efficiency.
Innovation Solution
A DC-DC converter with an input power detection unit and a voltage conversion unit that maintains a constant ratio of input voltage to input current, using a switch to control the current and impedance, ensuring constant input impedance regardless of battery charge state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power receiving device charges a battery, then the battery charge condition changes, but the input impedance changes dynamically causing impedance mismatch
Solution Approach 1:
The patent applies dynamics by making the load resistance variable rather than fixed. The load resistance is dynamically adjusted based on the battery charge condition to maintain constant input impedance. This is achieved through a control unit that detects the battery charge state and adjusts the load resistance accordingly, allowing the system to adapt to changing conditions while maintaining impedance matching.
Solution Approach 2:
The patent implements feedback by detecting the battery charge condition and using this information to adjust the load resistance. The control unit continuously monitors the battery state and modifies the load resistance in response, creating a closed-loop control system that maintains constant input impedance despite changes in battery charge level.
2Device complexity
If the load resistance is fixed, then the device structure is simple, but the input impedance changes with battery charge condition reducing power feeding efficiency
Solution Approach 1:
The patent transforms the static load resistance into a dynamic variable parameter. By making the load resistance adjustable based on battery charge condition, the system maintains optimal power transfer efficiency throughout the charging process. The control unit adjusts the load resistance to compensate for battery voltage changes, preventing impedance mismatch and energy loss.
Solution Approach 2:
The patent changes the parameter of load resistance from a fixed value to a variable parameter that adapts to battery charge conditions. This parameter change allows the system to maintain constant input impedance across different charging stages, maximizing power feeding efficiency while managing the increased device complexity through controlled adjustment mechanisms.
Data Source
AI summary
A circuit capable of keeping input impedance constant is provided. Further, a circuit which can contribute to improvement in power feeding efficiency in power feeding by a magnetic resonance method is provided. A voltage (a former voltage) proportional to a direct-current voltage input to a DC-DC converter from the outside and a voltage (a latter voltage) proportional to a current input from the outside are detected, and the ratio of the former voltage and the latter voltage are held constant. Accordingly, input impedance can be kept constant. Further, impedance conversion is performed in the DC-DC converter. Thus, even when the battery in which power feeding is performed exists on an output side of the DC-DC converter, input impedance can be kept constant. Consequently, power can be supplied to a power receiving device including the DC-DC converter and the battery with high power feeding efficiency by a magnetic resonance method.