Wireless Power Receiver Tuning for Low-Loss High-Power Charging
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Solution Overview
Problem
Inductive wireless power transfer systems face significant power loss and heat generation due to high AC resistance in embedded receivers, particularly in handheld devices, limiting the charging power to 5W and causing inefficiencies and increased device temperature.
Innovation Solution
The solution involves optimizing the receiver circuitry by adjusting the voltage-current ratio to minimize ohmic losses, regulating the magnetic field strength, and using a controller to toggle FETs in the rectifier to reduce power loss, along with modifying the input voltage to the DC-DC converter based on feedback to minimize overall losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher power levels are transferred to match wired charger capabilities (15W or more), then charging power is improved, but power losses on the receiver increase causing temperature rise
Solution Approach 1:
The patent implements dynamic adjustment of the receiver's operating parameters, specifically varying the resonant frequency and impedance matching conditions in real-time based on the transmitted power level and receiver temperature. This allows the system to optimize power transfer efficiency across different charging power levels, reducing power losses when operating at higher power levels above 5W.
Solution Approach 2:
The invention changes key operating parameters including the resonant frequency of the receiver coil, the switching frequency of the rectifier circuit, and the impedance matching conditions. By dynamically adjusting these parameters, the system maintains optimal power transfer efficiency across a wide range of power levels, enabling higher charging power while minimizing power losses and heat generation.
2Power
If the charging power is increased beyond 5W, then power transfer capability is improved, but device temperature increases due to power losses
Solution Approach 1:
The patent incorporates a feedback mechanism that continuously monitors the receiver temperature and transmitted power level, and adjusts the operating parameters accordingly. When temperature rises or power level increases beyond 5W, the system dynamically adjusts the resonant frequency and impedance matching to optimize efficiency and reduce heat generation, maintaining safe operating temperatures even at higher power levels.
Solution Approach 2:
The invention implements periodic adjustment of operating parameters including pulse-width modulation of the rectifier switching and periodic tuning of the resonant frequency. This periodic action allows the system to efficiently transfer higher power levels while distributing heat generation over time, preventing excessive temperature rise during continuous charging operations.
3Ease of operation
If coils and ferrites are used in embedded receivers, then wireless power reception is enabled, but AC resistance increases (up to 0.5ohm) due to form factor constraints
Solution Approach 1:
The patent changes the operating frequency parameter to optimize the performance of the coil and ferrite combination in embedded receivers. By operating at specifically tuned resonant frequencies and adjusting the switching frequency of the rectifier circuit, the system minimizes the effective AC resistance of the receiver components, reducing power losses despite the constrained form factor and presence of metal shielding.
Solution Approach 2:
The invention applies local quality optimization by using selective ferrite shielding in specific regions of the receiver coil, and by locally adjusting the impedance matching network. This allows different parts of the receiver to have optimized characteristics for their specific function, reducing overall AC resistance while maintaining effective wireless power reception in the embedded form factor.
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 reduces power loss and heat generation, enabling higher power transfer efficiency, potentially increasing charging power beyond 5W and maintaining device temperature within safe limits.
Implementation Method 1
a receiver (100) inductively powered by a transmitter for supplying power to a load (107)
Implementation Method 2
a resonance circuit (102-104)
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
According to one aspect of the present disclosed subject matter, a receiver inductively powered by a transmitter for powering a load, the receiver comprising: a resonance circuit capable of tuning its resonance frequency for coupling with the transmitter and generate AC voltage; a power supply section configured to rectify the AC voltage and adjust a DC current and a DC voltage to the load; and a control and communication section designed to set parameters for the receiver and communicate operation points (OP) to the transmitter, wherein the parameters and the OP derived from determining a minimal power loss of the receiver.