Contactless Power Transmission Circuit Voltage Control
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Solution Overview
Problem
Contactless power transmission systems face efficiency deterioration and increased load on circuit elements due to voltage fluctuations caused by positional deviations between coils, leading to excessive transmission current and potential overheating.
Innovation Solution
A contactless power transmission circuit with a control circuit that adjusts the period of alternating voltage output based on detected voltage and current differences, maintaining transmission current at a predetermined maximum value and limiting output voltage to prevent overheating, using a driving circuit, rectifier circuit, transmission current detecting circuit, and output voltage detecting circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the input voltage range of the DCDC converter is broadened to accommodate voltage fluctuations from rectifier output, then the charging efficiency of the battery deteriorates
Solution Approach 1:
The control circuit continuously monitors the rectifier output voltage and adjusts the DCDC converter operating parameters in real-time based on the detected voltage level, enabling adaptive operation that maintains high efficiency across varying voltage conditions without requiring a broadly designed converter
Solution Approach 2:
The system dynamically changes the operating parameters of the DCDC converter (such as switching frequency or duty cycle) according to the rectifier output voltage level, allowing the converter to operate at optimal efficiency points across different voltage conditions rather than being fixed at a single operating point
2Power
If the transmission current is increased to compensate for decreased rectifier output voltage, then the load on circuit elements increases and parts such as the coil overheat
Solution Approach 1:
The control circuit monitors the rectifier output voltage and adjusts the transmission current accordingly, preventing excessive current increase when voltage decreases, thereby avoiding overheating of the transmitting coil and circuit elements
Solution Approach 2:
The system dynamically adjusts the transmission current based on real-time voltage conditions, optimizing the current level to maintain power transmission while preventing thermal overload of components
3Adaptability or versatility
If the position deviation between transmitting and receiving coils increases, then the coupling coefficient decreases causing voltage fluctuation and current increase
Solution Approach 1:
The control circuit detects changes in coupling coefficient caused by position deviation and adjusts operating parameters to compensate, maintaining stable power transmission despite positional variations between coils
Solution Approach 2:
The system dynamically adapts its operation based on the coupling coefficient, adjusting transmission parameters in real-time to maintain reliable power transmission across varying positional conditions
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
The solution effectively narrows voltage fluctuations and maintains transmission current within safe limits, preventing overheating and improving efficiency by controlling the alternating voltage period based on real-time feedback from detecting circuits.
Implementation Method 1
a power transmission system using the contactless power transmission technology has been disclosed in Patent Document 1
Implementation Method 2
a rectifier portion connected to the coil on the power-receiving side (the antenna on the power-receiving side)
Data Source
AI summary
The present invention provides a contactless power transmission circuit which is capable of narrowing a fluctuation extent of an output voltage output by a power receiving coil via a rectifier circuit. The contactless power transmission circuit controls a period of an alternating voltage output from a driving circuit based on a smaller one of either of a first command value and a second command value. Here, the first command value is one based on a difference between a detected value of the output voltage from the rectifier circuit and a target value. The second command value is one calculated based on a difference between a detected value of a transmission current flowing through the power transmitting coil and a target value.