Wireless Charging Receiver Impedance Tuning
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Solution Overview
Problem
Existing wireless charging systems face inefficiencies in power transfer due to varying operating conditions, such as rectifier voltage, power to the rectifier, and orientation and distance between transmitter and receiver antennas, particularly for small antennas.
Innovation Solution
A method and apparatus for automatically tuning the antenna impedance of a wireless charging receiver by adjusting the capacitance of variable capacitors in the resonator network, using a digital-to-analog converter to control the impedance matching circuit, ensuring optimal power transfer by matching the impedance to the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed capacitance resonator network is used in the wireless charging receiver, then the device structure is simple, but the power transfer efficiency deteriorates under varying operating conditions
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed capacitance components with variable capacitors that can dynamically adjust their capacitance values. The resonator network includes variable capacitors controlled by a control circuit that receives feedback about power transfer efficiency and adjusts capacitance in real-time to maintain optimal resonance conditions despite varying operating conditions such as distance, orientation, and load changes.
Solution Approach 2:
The patent implements parameter changes by modifying the capacitance parameter of the resonator network components. The control circuit varies the capacitance values of variable capacitors based on detected operating conditions and error signals, allowing the system to adapt to different transmission distances, orientations, and power levels to maintain maximum power transfer efficiency.
2Loss of energy
If the capacitance of the resonator network is adjusted to optimize power transfer, then the power transfer efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent applies feedback by implementing a control circuit that continuously monitors the rectifier voltage and compares it against a target value to generate an error signal. This error signal feeds back to the variable capacitor control mechanism, creating a closed-loop system that automatically adjusts capacitance to maintain optimal power transfer efficiency without requiring complex external control systems.
Solution Approach 2:
The system implements self-service through its automatic tuning capability where the control circuit autonomously adjusts the variable capacitors based on real-time operating conditions. The system self-regulates the resonator network impedance to match optimal values for maximum power transfer, eliminating the need for manual intervention or complex external tuning mechanisms.
3Adaptability or versatility
If variable capacitors are used in the resonator network, then the adaptability to operating conditions is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing a control circuit that handles multiple functions: monitoring rectifier voltage, generating error signals, and controlling variable capacitors. This multi-functional approach allows the system to adapt to various operating conditions (different distances, orientations, loads) using a single integrated control mechanism rather than separate systems for each function.
Solution Approach 2:
The variable capacitor system with automatic control implements self-service by autonomously adapting to changing operating conditions. The control circuit continuously adjusts capacitance values based on real-time feedback, enabling the system to maintain optimal performance across diverse scenarios without external intervention, thereby achieving high adaptability with controlled 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
This approach enhances charging efficiency by maintaining the rectifier voltage within desired limits, improving power transfer efficiency under changing operating conditions.
Implementation Method 1
A typical wireless charging receiver includes a series-parallel resonator connected to a rectifier circuit
Implementation Method 2
The electrical coupling efficiency for a particular transmitter/receiver antenna combination varies both spatially and by operating conditions
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A wireless charging receiver operates on a resonance principle and includes an impedance matching circuit coupled between an antenna and a rectifier circuit. The impedance matching circuit has both series-connected and parallel-connected capacitors. At least one of the capacitors is a tunable variable capacitor. A method is provided for automatically adjusting a capacitance value of the at least one variable capacitor based on an error voltage between a target rectifier voltage and a measured rectifier voltage. Automatically adjusting the antenna impedance of the receiver provides for improved power transfer efficiency for changing operating conditions. In one embodiment, one or more of the parallel-connected capacitors are variable capacitors. In another embodiment, one or more of the series-connected capacitors are variable capacitors.