Wireless Power Feeder Frequency Control for Resonance Tracking
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Solution Overview
Problem
Current wireless power feeding technologies, particularly the magnetic field resonance type, lack a mechanism for effectively controlling the magnitude of transmission power, leading to inefficiencies and increased costs due to the use of DC/DC converters with significant power loss.
Innovation Solution
A wireless power feeder system that includes a power transmission control circuit, a feeding coil circuit with a capacitor, and a phase detection circuit to adjust the drive frequency of AC power, ensuring the phase difference between voltage and current phases is minimized, thereby tracking the resonance frequency and enhancing power transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a DC/DC converter is used to control transmission power magnitude, then power control capability is improved, but power loss increases by 10 to 20% and cost increases
Solution Approach 1:
The patent changes the control parameter from input voltage (using DC/DC converter) to drive frequency. By adjusting the drive frequency of the AC power source, the system controls the magnitude of transmission power without the energy losses associated with voltage conversion. This frequency-based control method maintains power control capability while eliminating the 10-20% power loss of DC/DC converters.
Solution Approach 2:
The patent replaces the mechanical/electrical DC/DC conversion system with a frequency control system. Instead of using a complex power conversion device with moving parts or complex circuitry, the invention uses frequency modulation of the AC power source to achieve power control, substituting a simpler, more efficient control mechanism.
2Ease of operation
If a DC/DC converter is used to control transmission power, then power control capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the complex DC/DC converter system with a frequency control system. The DC/DC converter requires complex power electronic circuits, control logic, and additional components, whereas the frequency control method uses the existing AC power source with adjustable frequency, significantly reducing device complexity and cost while maintaining power control capability.
Solution Approach 2:
The AC power source serves multiple functions: it provides both the power for wireless transmission and the control signal for power magnitude adjustment. By making the drive frequency adjustable, the same power source becomes a control element, eliminating the need for separate control devices and reducing overall system complexity.
3Loss of energy
If drive frequency is adjusted to track resonance frequency, then power transmission efficiency is improved, but control system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the phase detection circuit continuously monitors the phase difference between voltage and current, and this information feeds back to the power transmission control circuit. The control circuit adjusts the drive frequency based on this feedback to maintain resonance, achieving high power transmission efficiency through a relatively simple closed-loop control system.
Solution Approach 2:
The patent uses phase difference as an indicator (analogous to a visual signal) of resonance status. By detecting changes in phase relationship between voltage and current, the system can determine whether it is at resonance and adjust accordingly, providing a simple and effective method for frequency tracking without complex measurement systems.
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 allows for precise control of power transmission efficiency, reducing power loss and costs by automatically adjusting the drive frequency to maintain optimal resonance, enabling efficient wireless power feeding while eliminating the need for costly DC/DC converters.
Implementation Method 1
When AC power is fed to the exciting coil, current also flows in the feeding coil according to the principle of electromagnetic induction
Data Source
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AI summary
Power is fed from a feeding coil L2 to a receiving coil L3 by magnetic resonance. A VCO alternately turns ON/OFF switching transistors Q1 and Q2 at a drive frequency fo, whereby AC current is fed to the feeding coil L2, and then the AC current is fed from the feeding coil L2 to the receiving coil L3. A phase detection circuit detects a phase difference between the current phase and voltage phase, and the VCO adjusts the drive frequency fo such that the phase difference becomes zero. In a current phase detection circuit and a voltage phase detection circuit, detection values of the current and voltage phases can be changed, respectively and intentionally.