Wireless Power Feeder Phase Detection Resonance Tracking
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Solution Overview
Problem
Existing wireless power feeding systems using magnetic field resonance type face challenges in maintaining drive frequency alignment with resonance frequency, leading to reduced power transmission efficiency and stability due to external distortions and variations.
Innovation Solution
A wireless power feeder device with a power transmission control circuit, phase detection circuit, and reset circuit that adjusts the drive frequency to track the resonance frequency by comparing voltage and current phases, and includes a detection coil to monitor resonance state without directly loading the feeding coil, ensuring stable operation even under external disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drive frequency is adjusted to track the resonance frequency using phase detection, then power transmission efficiency is improved, but the system becomes sensitive to external waveform distortions causing frequency deviation
Solution Approach 1:
A detection coil is introduced as an intermediary element that magnetically couples with the feeding coil to sense the resonance state. This indirect detection method isolates the frequency detection mechanism from direct electrical connection, preventing external waveform distortions from causing false frequency adjustments while maintaining accurate resonance tracking through magnetic field coupling
Solution Approach 2:
The system implements a feedback 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. This closed-loop control enables automatic tracking of resonance frequency to maximize power transmission efficiency while the detection coil provides noise-immune feedback signals
2Measurement precision
If a detection coil is used to monitor resonance state indirectly, then measurement precision is improved without loading the feeding coil, but device complexity increases
Solution Approach 1:
The detection coil serves as a non-intrusive intermediary that magnetically couples with the feeding coil to sense resonance characteristics. This indirect measurement approach provides accurate resonance frequency detection without electrical loading of the feeding coil, and the magnetic coupling mechanism naturally isolates the detection system from electrical noise and distortions
Solution Approach 2:
The system replaces direct electrical measurement methods with magnetic field-based detection. By using magnetic coupling between the feeding coil and detection coil, the system achieves precise resonance monitoring without direct electrical connection, eliminating the need for complex electrical isolation circuits and reducing overall system complexity
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 solution enhances power transmission efficiency and stability by accurately tracking the resonance frequency, maintaining high efficiency and preventing frequency deviations caused by external factors, thus ensuring reliable wireless power transfer.
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 the phase difference between the voltage phase and the current phase of the AC power and generates a phase difference indicating voltage in accordance with the magnitude of the phase difference
Implementation Method 4
a reset circuit that is connected to a voltage line to which the phase difference indicating voltage is fed so as to reduce the phase difference indicating voltage
Data Source
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AI summary
Power is transmitted from a feeding coil L2 to a receiving coil L3 by magnetic resonance. A VCO 202 alternately turns ON/OFF switching transistors Q1 and Q2 to feed AC current to the feeding coil L2, whereby the AC power is fed from the feeding coil L2 to the receiving coil L3. An AC magnetic field generated by AC current IS flowing in the feeding coil L2 causes inductive current ISS to flow in a detection coil LSS. A phase detection circuit 150 compares the phase of AC voltage generated by the VCO 202 and phase of the inductive current ISS to detect the phase difference between voltage and current phases and generates phase difference indicating voltage indicating the magnitude of the phase difference. The reset circuit 102 forcibly reduces the phase difference indicating voltage when the phase difference indicating voltage exceeds a predetermined threshold.