Contactless Charging Efficiency Estimation via Primary Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing contactless electric power supply systems cannot estimate power transmission efficiency when the power receiving circuit, including the power receiving coil, is not in an electric conduction state, as they rely on measuring electric current, which is not possible in such scenarios.
Innovation Solution
The system estimates power transmission efficiency from a detected value of a sensor measuring current or voltage applied to the power transmitting circuit, correlating it with the distance between coils, allowing efficiency estimation even when the power receiving circuit is not conducting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission efficiency is calculated from the received electric power of the power receiving means, then transmission efficiency can be measured, but transmission efficiency cannot be calculated when the power receiving circuit is not in an electric conduction state
Solution Approach 1:
The patent introduces an intermediary approach by using the primary current detector to measure current on the transmitting side as a proxy indicator. Instead of directly measuring received power (which requires conduction), the system uses the primary current as an intermediate parameter that correlates with transmission efficiency, enabling indirect measurement without requiring the power receiving circuit to be in conduction state
Solution Approach 2:
The patent replaces the electrical measurement method (measuring received power) with an alternative measurement approach (measuring primary current). This substitution allows the system to determine transmission efficiency through a different physical quantity that can be measured even when the receiving circuit is not conducting, thus resolving the limitation
2Reliability
If power transmission is stopped to prevent obstacles, then safety is improved, but power supply continuity is disrupted
Solution Approach 1:
The patent applies partial action by using minute electric power for detection purposes before full power transmission begins. This allows the system to perform efficiency measurements and obstacle detection using a small amount of power, then gradually increase to full power transmission if conditions are satisfactory, thereby maintaining continuity while ensuring safety
Solution Approach 2:
The patent implements preliminary action by conducting transmission efficiency measurements and safety checks before initiating full power transmission. The system first measures efficiency using primary current detection, verifies conditions are appropriate, and only then proceeds with full power supply, preventing interruptions caused by late-stage obstacle detection
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 the estimation of power transmission efficiency from the power transmitting side, even when the power receiving circuit is not in an electric conduction state, facilitating effective power transfer and positioning verification for contactless charging systems.
Implementation Method 1
power transmitting means; power receiving means for receiving an electric power from the power transmitting means in a contactless manner
Data Source
Figure 1
Figure 2
Figure 3
AI summary
contactless electric power supply device 100 to charge a battery 28 of a vehicle includes a power transmitting circuit 101 having a power transmitting coil 12 and a charging circuit 201 having a power receiving coil 22. An electric power is transmitted from power transmitting coil 12 to power receiving coil 22 in a contactless manner. When the vehicle approaches power supply device 100, a trial power supply in which a electric power transmission through a minute electric power is carried out is executed and a power transmission efficiency from power transmitting coil 12 to power receiving coil 22 is estimated on a basis of a current flowing through power transmitting circuit 101. From this power transmission efficiency, a determination of whether power receiving coil 22 falls in a range in which battery 28 is chargeable with respect to power transmitting coil 12 is made.