Non-contact Power Feeding Control via Coupling Estimation
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Solution Overview
Problem
Non-contact power feeding apparatuses face challenges in setting output power to an available output power based on the withstand voltage or current of secondary coils and capacitors, leading to increased time for the output power to reach the available output power.
Innovation Solution
The apparatus estimates the coupling state between primary and secondary windings, calculates the available output power considering the limit values of circuit elements, and adjusts the voltage command value accordingly to reduce the control time for reaching the available output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the output voltage is set without taking into consideration the withstand voltage or withstand current of the secondary coil, capacitor, or the like, then the voltage control can be simplified, but the control time increases and the output power takes longer to reach the available output power
Solution Approach 1:
The system performs preliminary measurement of the coupling coefficient before power transmission begins. Based on this pre-measured coupling state, the controller calculates and determines the appropriate output voltage that considers the withstand voltage and current limits of circuit elements. This preliminary action allows the system to directly set the optimal voltage without iterative adjustment, thereby reducing control time while maintaining safety.
2Productivity
If the output power is increased to reach the available output power faster, then the productivity is improved, but the risk of exceeding the withstand voltage or current of circuit elements increases
Solution Approach 1:
The system dynamically adjusts the output voltage parameter based on the measured coupling coefficient. By establishing a relationship between the coupling state and the maximum safe output power, the controller can determine the precise voltage level that achieves maximum productivity without exceeding the withstand voltage or current limits of circuit elements such as the secondary coil and capacitor. This parameter adjustment ensures both fast power delivery and circuit safety.
3Productivity
If the coupling state is measured and the output voltage is adjusted accordingly, then the power delivery efficiency is improved, but the measurement and control process becomes more complex
Solution Approach 1:
The system uses the existing primary and secondary coils to perform self-measurement of the coupling coefficient through electrical characteristics during the power transmission process. The controller automatically calculates the coupling state from measured voltage and current values, and autonomously adjusts the output voltage based on this self-determined coupling information. This self-service approach improves power delivery efficiency without requiring additional external measurement devices or complex control procedures.
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 approach reduces the time for the output power to reach the available output power by accurately determining the available output power based on the coupling state and limit values of circuit elements, enhancing efficiency and speed in power delivery.
Implementation Method 1
a primary coil and a secondary coil that are magnetically coupled to each other
Data Source
AI summary
There is provided a non-contact power feeding apparatus which transmits, by at least magnetic coupling, an electric power in a non-contact manner to a power reception coil from a power transmission coil electrically connected to an alternating-current power source and which outputs an electric power to a load electrically connected to the power reception coil. The non-contact power feeding apparatus includes: a coupling state estimator configured to estimate a coupling state between the power transmission coil and the power reception coil; and an available output power calculator configured to calculate an available output power that can be output to the load, based on a limit value of a circuit element of a power feeding circuit including the power transmission coil and the power reception coil and on the coupling state.