Contactless Power Transfer Ramp-Up to Prevent Overcurrent
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Solution Overview
Problem
Existing contactless power transmission systems face issues such as increased load and overcurrent detection due to rapid starts of power supply when a vehicle's coil approaches the transmitting coil, leading to potential power supply stops.
Innovation Solution
A contactless power transmission system with a control device that sets initial power transmission to less than a predetermined power and gradually increases it over time, using a power conversion unit with switching elements and a current sensor to manage power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power transmission starts at full power when the vehicle approaches, then power supply responsiveness is improved, but current increase and overcurrent detection occur causing power supply stop
Solution Approach 1:
The control device performs preliminary action by setting transmission power to a predetermined value lower than the required power at the start of power transmission, before the vehicle fully approaches. This preliminary controlled start prevents current hunting and overcurrent detection while maintaining power supply responsiveness through gradual power increase.
2Productivity
If transmission power is rapidly increased to meet required power, then power delivery efficiency is improved, but load increase and frequency drop occur in power supply system
Solution Approach 1:
The control device applies dynamics by continuously adjusting transmission power based on the approach distance between the vehicle and transmitter. Power increases gradually as the vehicle approaches, optimizing power delivery efficiency while preventing sudden load increases and frequency drops in the power supply system.
Solution Approach 2:
The control device changes the transmission power parameter dynamically based on vehicle approach distance. By adjusting this key parameter from a predetermined lower value to the required power level, the system achieves efficient power delivery while maintaining power supply system stability and avoiding frequency drops.
3Use of energy by moving object
If power transmission is maintained at high level, then power receiving efficiency is improved, but current hunting and overcurrent detection cause power supply stop
Solution Approach 1:
The control device performs preliminary action by starting power transmission at a predetermined lower power level before the vehicle is in optimal position. This prevents current hunting and overcurrent detection while maintaining power receiving efficiency through controlled gradual power increase as the vehicle approaches.
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 approach effectively suppresses current increases and load spikes during power transmission initiation, preventing overcurrent situations and maintaining stable power delivery.
Implementation Method 1
a power transmitting unit 8 having a coil 8a for sending out AC power to be transmitted to a power receiving device 4 in a non-contact manner
Data Source
AI summary
A contactless power transmission system includes a power transmitting unit, a power transmission power conversion unit, and a power transmission side control device. The power transmitting unit has a primary coil for sending out AC power to be transmitted to a power receiving device in a non-contact manner. The power transmission power conversion unit has a plurality of transistors connected to the primary coil. The power transmission power conversion unit converts a DC power supplied from a power source unit to an AC power. The power transmission side control device sets transmission power at a start period of initial power transmission by the power transmitting unit to less than a predetermined power. The power transmission side control device changes the transmission power in a tendency of increasing toward a predetermined power as a time elapses from a start of power transmission by the power transmitting unit.