Wireless Power Supply Impedance Control for EV Efficiency
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Solution Overview
Problem
The magnetic field resonance method for wireless power transmission has high power transmission efficiency but requires improvement in overall system power efficiency, particularly for high-power applications like electric vehicles, where both the power-supplying and power-receiving devices need enhanced efficiency.
Innovation Solution
A wireless power supply device with a rectifier circuit, conversion unit, communication unit, and control unit that adjusts the power supply impedance of the load within a predetermined range to optimize power transmission efficiency, eliminating the need for additional impedance adjustment circuits in the power-receiving device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic field resonance method is used for wireless power transmission, then power transmission efficiency is improved, but overall system power efficiency deteriorates due to high power consumption in power-receiving device
Solution Approach 1:
The patent inverts the conventional control approach by having the power-supplying device control the power supply impedance of the load in the power-receiving device, rather than having the power-receiving device control its own impedance. This inversion allows the power-supplying device to optimize the overall system efficiency by adjusting the load impedance to fall within a predetermined range, thereby reducing power consumption in the power-receiving device while maintaining high power transmission efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the power-supplying device receives information from the power-receiving device regarding power supply status, and uses this feedback to adjust the power supply impedance. The control unit in the power-supplying device continuously monitors the load impedance and adjusts the conversion unit to maintain the impedance within the optimal range, creating a closed-loop control system that optimizes overall power efficiency.
2Productivity
If power-receiving device includes impedance adjustment circuit, then power supply efficiency is improved, but device complexity increases
Solution Approach 1:
The patent extracts the impedance adjustment function from the power-receiving device and relocates it to the power-supplying device. By removing the need for complex impedance adjustment circuits in the power-receiving device and implementing the control functionality in the power-supplying device instead, the patent simplifies the power-receiving device structure while maintaining high power supply efficiency through centralized impedance control.
Solution Approach 2:
The power-supplying device is given multiple functions: it not only transmits power wirelessly but also performs impedance adjustment and control of the load in the power-receiving device. This multi-functionality allows the system to achieve efficient power supply without adding complexity to the power-receiving device, as the control capabilities are consolidated in the power-supplying device.
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 improves the overall power efficiency of the wireless power supply system by controlling the power supply impedance, allowing for high-efficiency power delivery to loads like batteries in electric vehicles, reducing power loss and eliminating the need for separate charging circuitry in the receiving device.
Implementation Method 1
In the magnetic field resonance method, a power-supplying-side resonator is constituted by equipping a power-supplying-side coil with a capacitor, and also a power-receiving-side resonator is constituted by equipping a power-receiving-side coil with a capacitor, so that electric power is transmitted between these two resonators.
Implementation Method 2
In the electromagnetic induction method, power is wirelessly transmitted by means of electromagnetic induction between a power-supplying-side coil and a power-receiving-side coil.
Data Source
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AI summary
A wireless power supply device and a wireless power supply system of the present invention include a rectifier circuit (1) to be connected to a commercial power source, a conversion unit which is connected to the rectifier circuit (1), a resonance circuit (8) which is connected to the conversion unit and transmits power toward a power-receiving device (R) wirelessly, a communication unit (11) which receives, from the power-receiving device (R), information relating to power supply to a load supplied with power, and a control unit which is connected to the communication unit (11) and the conversion unit and controls the conversion unit based on the information so that the value of power supply impedance of the load falls within a predetermined range.