Contactless Power Transmission Frequency Control via Receiver Feedback
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Solution Overview
Problem
Contactless power transmission apparatuses face challenges in determining the frequency of AC power to be applied to a transmitter coil for maintaining a constant voltage output, as this frequency varies with the degree of coupling between the transmitter and receiver coils.
Innovation Solution
A contactless power transmission apparatus with a transmitter and receiver system, including a power supply circuit with adjustable switching frequency and voltage, a current detection circuit, and a control circuit that communicates with the receiver to detect the frequency at which a constant voltage is output by measuring current and voltage values, and adjusts the frequency accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the frequency of AC power applied to the transmitter coil is adjusted to achieve high power transmission efficiency, then the power transmission efficiency is improved, but the output voltage becomes unstable and deviates from constant voltage output
Solution Approach 1:
The patent implements a feedback mechanism where the receiver end detects the output voltage and transmits determination information to the transmitter end. The transmitter end's control circuit uses this feedback to detect the switching frequency at which constant voltage is output, thereby adjusting the AC power frequency to maintain both high efficiency and stable voltage output.
Solution Approach 2:
The patent replaces direct voltage measurement and control at the transmitter end with a communication-based system where the receiver end performs voltage detection and communicates results back. This substitution allows the transmitter to adjust frequency based on receiver feedback, resolving the conflict between efficiency optimization and voltage stability.
2Productivity
If the frequency of AC power applied to the transmitter coil is adjusted based on coupling degree, then power transmission efficiency is optimized, but the frequency at which constant voltage is output varies and becomes difficult to determine
Solution Approach 1:
The receiver end provides feedback information about whether constant voltage is being output at the current frequency. This feedback enables the transmitter end to iteratively detect and identify the precise switching frequency that achieves both optimal coupling efficiency and constant voltage output, regardless of coupling degree variations.
Solution Approach 2:
The system uses the receiver end's own voltage detection capability to provide the information needed for frequency optimization. The receiver essentially performs the measurement and communicates the result, allowing the transmitter to self-adjust to the correct frequency without requiring complex external measurement equipment.
3Measurement precision
If the switching frequency is varied to find the optimal frequency for constant voltage output, then accurate frequency detection is achieved, but the time required to detect and adjust frequency increases
Solution Approach 1:
The system performs preliminary frequency sweeping to identify the range where constant voltage output occurs. By pre-detecting the relationship between switching frequency and constant voltage output condition, the system can quickly converge to the optimal frequency without exhaustive searching during operation, reducing detection time while maintaining accuracy.
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 accurate detection and maintenance of a constant voltage output across varying degrees of coupling and load resistances, enhancing power transmission efficiency and timely resumption of power supply.
Implementation Method 1
a resonant circuit including a receiver coil that receives electric power from the transmitter
Implementation Method 2
a resonant capacitor that resonates with the receiver coil in response to electric power from the transmitter
Data Source
AI summary
A contactless power transmission apparatus includes a receiver that includes a resonant circuit that receives electric power from a transmitter. The receiver causes, in response to a measurement value of an output voltage of electric power output from the resonant circuit being out of a predetermined allowable range of voltages, a short circuit to short-circuit the resonant circuit and transmits determination information indicating that the contactless power transmission apparatus is not outputting a constant voltage. In response to the determination information, the transmitter in the contactless power transmission apparatus detects a switching frequency of alternating current power to be supplied to a transmitter coil from a power supply circuit at which the contactless power transmission apparatus outputs a constant voltage in accordance with a measurement value of a current through the transmitter coil.