Wireless Power Feeder Phase Control 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 feeding coil, a power transmission control circuit, and a phase detection circuit, which adjusts the drive frequency of AC power to minimize phase differences between voltage and current phases, allowing for enhanced power transmission efficiency and manual control of power transmission while automatically optimizing for maximum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic field resonance type wireless power feeding is used for intermediate range power transmission, then power transmission efficiency is improved, but control of transmission power magnitude becomes difficult
Solution Approach 1:
The patent implements a feedback control mechanism where the phase detection circuit continuously monitors the phase difference between voltage and current, and the power transmission control circuit adjusts the drive frequency based on this feedback to maintain optimal resonance conditions while controlling power transmission magnitude
Solution Approach 2:
The patent controls the magnitude of transmission power by changing the drive frequency parameter of the AC power supplied to the feeding coil. By adjusting the frequency away from or toward the resonance frequency, the system can control the amount of power transmitted while maintaining efficient operation
2Ease of operation
If DC/DC converter is used to control transmission power magnitude, then power control is achieved, but power loss increases and cost increases
Solution Approach 1:
The patent replaces the mechanical/electronic DC/DC converter system with a frequency-based control mechanism. Instead of converting DC voltage levels to control power, the system directly controls AC power magnitude by adjusting the drive frequency of the feeding coil, eliminating the need for intermediate conversion stages and associated losses
Solution Approach 2:
The system changes the control parameter from voltage conversion (DC/DC) to frequency adjustment (AC frequency). By varying the frequency of AC power supplied to the feeding coil, the system achieves power control without the energy losses and costs associated with DC/DC converters
3Loss of energy
If drive frequency is adjusted to track resonance frequency, then power transmission efficiency is maximized, but system complexity increases
Solution Approach 1:
The patent uses a feedback control loop where the phase detection circuit monitors the phase relationship between voltage and current, and the power transmission control circuit automatically adjusts the drive frequency to minimize phase difference, thereby tracking the resonance frequency automatically without requiring complex external control systems
Solution Approach 2:
The system performs self-adjustment of the drive frequency based on the phase detection feedback. The power transmission control circuit autonomously modifies the frequency to maintain optimal resonance conditions, eliminating the need for external frequency tuning mechanisms or complex control 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
The system achieves high power transmission efficiency by tracking the resonance frequency, reducing power loss, and enabling easy control of power transmission, thus improving the applicability and cost-effectiveness of wireless power feeding.
Implementation Method 1
When the feeding coil generates a magnetic field to cause the feeding coil and receiving coil to magnetically resonate, large current flows in the receiving coil
Implementation Method 2
When AC power is fed to the exciting coil, current also flows in the feeding coil according to the principle of electromagnetic induction
Implementation Method 3
a phase detection circuit that detects a phase difference between the voltage phase and current phase of the AC power
Implementation Method 4
The power transmission control circuit adjusts the drive frequency of the AC power such that the phase difference is reduced
Data Source
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.