Contactless Power Supply Charge Detection via Reflected Power
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Solution Overview
Problem
Contactless power supply systems face challenges in reliably determining when a power storage device is fully charged, leading to potential overcharging and wasteful power consumption, especially when using methods like constant current charging where the time rate of change of reflected power remains consistent, making it difficult for conventional systems to differentiate between charge completion and fluctuations.
Innovation Solution
A contactless power supply system that includes a power transmitter with a high-frequency power supply, controller, and power detector, and a power receiver with a charging circuit and controller, which uses a significant increase in reflected power upon interrupting power supply to determine charge completion, allowing for reliable stopping of power transmission without communication means, applicable to various charging modes including constant current charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the time rate of change of reflected power is used to determine charge completion, then charge completion can be detected without communication means, but the detection reliability deteriorates due to fluctuations in reflected power causing premature stopping
Solution Approach 1:
The power receiver performs preliminary action by interrupting the power supply to the power storage device before the power transmitter detects charge completion. This causes a significant increase in reflected power that clearly indicates charge completion, allowing the power transmitter to reliably detect the state without communication means and avoid premature stopping due to fluctuations.
2Productivity
If constant current charging is used for fast charging, then charging speed is improved, but the ability to determine charge completion deteriorates because the time rate of change of reflected power remains substantially the same throughout charging
Solution Approach 1:
The power receiver interrupts power supply to the power storage device when charging is complete, causing a significant increase in reflected power. This allows the power transmitter to detect charge completion accurately even during constant current charging where the time rate of change of reflected power remains substantially the same throughout the charging process.
3Duration of action of stationary object
If the power transmitter continues to feed power to a fully charged power storage device, then power transmission continuity is maintained, but harmful effects occur including overcharging that reduces device life and increases wasteful power consumption
Solution Approach 1:
The power receiver provides feedback to the power transmitter by interrupting power supply when the power storage device is fully charged, causing a significant increase in reflected power. The power transmitter detects this increase and stops power transmission, preventing overcharging and reducing wasteful power consumption while maintaining power transmission continuity during actual charging.
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 determination of charge completion, preventing overcharging and reducing wasteful power consumption by utilizing a significant increase in reflected power upon power interruption, effectively managing power supply across different charging methods.
Implementation Method 1
Contactless power supply systems recently known in the art magnetically couple a power transmitter to a power receiver through a pair of coils. Alternating current (AC) power generated by the power transmitter is transmitted to the power receiver through the magnetically coupled coils without physical contact.
Implementation Method 2
a power detector that detects a state in which the reflected power increases significantly
Data Source
Figure 1
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Figure 4
AI summary
A contactless power supply system includes a power transmitter (1) and a power receiver (2). The power transmitter (1) generates high-frequency power and contactlessly transmits the power to the power receiver (2). The power transmitter (1) detects reflected power from the power receiver (2) and stops the transmission of the power to the power receiver (2) with reference to the reflected power. The power receiver (2) receives the high-frequency power from the power transmitter (1) and converts the received power into direct current power for charging a power storage device (22). A switch (233) is operated to electrically connect or disconnect a path to supply the direct current power to the power storage device (22). The power receiver (2) includes a controller (24) for operating the switch (233) to electrically disconnect the power supply path when the power storage device (22) is in the full charge state.