Wireless Power Transmission Foreign Substance Detection
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Solution Overview
Problem
Conventional wireless power transmission systems face challenges in accurately detecting foreign substances during power transmission, leading to potential overheating and reduced efficiency due to the difficulty in distinguishing foreign substances using the same frequency as power transmission, which results in low SN ratio and inaccurate sensing.
Innovation Solution
A power transmission device that includes an inverter, an oscillator, and a foreign substance detector, which performs a series of multiple processes to determine the presence of foreign substances by varying the frequency and dividing the detection and transmission periods, allowing for accurate sensing without significantly disrupting power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign substance detection is performed using the same frequency as power transmission, then power transmission can continue without interruption, but detection accuracy deteriorates due to low SN ratio
Solution Approach 1:
The system performs foreign substance detection periodically by switching between detection mode (using oscillator at detection frequency) and power transmission mode (using inverter at transmission frequency). This periodic switching allows accurate detection while maintaining continuous power transmission capability, resolving the contradiction between detection accuracy and transmission continuity.
Solution Approach 2:
The system changes the frequency parameter for detection purposes. Instead of using the same frequency as power transmission, the oscillator generates detection signals at a different frequency to achieve high SN ratio and accurate foreign substance detection, while the inverter continues power transmission at the original transmission frequency.
2Measurement precision
If foreign substance detection is performed frequently to ensure safety, then detection accuracy improves, but power transmission efficiency deteriorates due to increased interruption time
Solution Approach 1:
The system performs a series of multiple detection processes (excessive action) within each detection period to ensure high detection accuracy. By dividing the detection into multiple steps including signal generation, measurement, and determination, the system achieves thorough detection while keeping each individual detection period short, thus maintaining power transmission efficiency.
Solution Approach 2:
The detection process is segmented into multiple distinct steps: oscillator generates detection signal, foreign substance detector performs measurement, and control circuit determines presence of foreign substance. This segmentation allows each step to be optimized independently and enables efficient use of detection time.
3Reliability
If multiple detection processes are performed in sequence to improve accuracy, then detection reliability improves, but detection time increases causing more power transmission interruptions
Solution Approach 1:
The system maintains continuity of useful action by quickly switching between detection and power transmission modes. The multiple detection processes are performed in rapid succession during brief detection periods, minimizing interruption time while ensuring reliable detection through the series of multiple processes.
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 solution enables high-accuracy foreign substance sensing during power transmission while maintaining efficient power transfer by shortening the foreign substance sensing session and preventing overheating, allowing the charging indicator to remain continuously lit.
Implementation Method 1
an inverter that generates first AC power and transmits the first AC power wirelessly to a first resonator of a power receiving device via a second resonator
Implementation Method 2
an oscillator that generates second AC power which is smaller than the first AC, and transmits the second AC power to the first resonator via a third resonator
Implementation Method 3
a foreign substance detector that performs a series of multiple processes thereby to determine whether or not a foreign substance is present between the first resonator and the third resonator based on a physical quantity at the third resonator, the physical quantity varying depending on the second AC power
Data Source
AI summary
A power transmission device includes an inverter, an oscillator, a foreign substance detector, and power transmission control circuitry. The foreign substance detector performs a series of multiple processes to determine whether or not a foreign substance is present between two resonators. The power transmission control circuitry repeats a foreign substance detection period and a power transmission period alternately. The foreign substance detection period is a period in which the foreign substance detector performs one of the series of multiple processes. The power transmission period is a period in which the inverter transmits AC power. The power transmission control circuitry also causes the foreign substance detector to divide the series of multiple processes and determine whether or not the foreign substance is present as a result of performing all of the divided series of multiple processes.