Wireless Power Receiver Detuned Resonator Voltage Control
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Solution Overview
Problem
Existing wireless power receivers face challenges in maintaining output voltage below a certain limit and power dissipation within acceptable thresholds across a range of operating frequencies, particularly due to high open-circuit voltages near resonant frequencies, which can lead to excessive power dissipation and temperature issues.
Innovation Solution
A wireless power receiver with a receiver resonator detuned from the transmitter resonator, utilizing a synchronous rectifier with a controller that selectively short-circuits the receiver resonator to maintain output voltage and power dissipation within limits, by activating or deactivating the short circuit based on voltage and current thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the receiver resonator is tuned to the transmitter resonant frequency to maximize power transfer efficiency, then the power transfer efficiency is improved, but the output voltage becomes excessively high causing power dissipation and temperature issues
Solution Approach 1:
The receiver resonator is pre-configured with a detuned resonant frequency (offset by 10-50 kHz from the transmitter frequency) before power transfer begins. This preliminary detuning prevents the voltage buildup that would occur at exact resonance, thereby limiting power dissipation and temperature rise while still maintaining acceptable power transfer efficiency through the controller's regulation actions.
2Temperature
If the receiver resonator is detuned from the transmitter resonant frequency to limit output voltage and power dissipation, then the temperature and power dissipation are reduced, but the power transfer efficiency decreases
Solution Approach 1:
The controller continuously monitors the power transfer efficiency and adjusts the receiver resonator's resonant frequency in real-time. When efficiency drops below a threshold due to detuning, the controller modifies the resonant frequency to optimize performance. This feedback mechanism allows the system to operate with a detuned resonator while dynamically compensating for efficiency losses, thus maintaining both temperature control and acceptable power transfer efficiency.
Solution Approach 2:
The receiver resonator's resonant frequency is made dynamic rather than fixed. The controller can adjust the resonant frequency on-the-fly by modifying the resonator's electrical characteristics (such as varying capacitor or inductor values). This dynamic adjustment enables the system to operate with a detuned frequency for thermal management while temporarily tuning to exact resonance when maximum efficiency is required, resolving the contradiction between temperature control and efficiency.
3Power
If high open-circuit voltages are allowed near resonant frequencies to maximize power delivery, then the power delivery capability is improved, but excessive power dissipation and component stress occur
Solution Approach 1:
The system changes the operating parameters by deliberately operating the receiver resonator at a detuned frequency (10-50 kHz offset) rather than at its natural resonant frequency. This parameter change shifts the operating point away from the high-voltage, high-dissipation region near exact resonance. The controller compensates for the reduced voltage by adjusting other system parameters, thereby delivering adequate power while significantly reducing power dissipation and component stress.
4Use of energy by moving object
If the resonant frequency is precisely matched between transmitter and receiver to optimize coupling, then the wireless power transfer efficiency is maximized, but the system becomes sensitive to frequency drift and environmental changes
Solution Approach 1:
The receiver resonator's frequency is made dynamically adjustable rather than fixed at a precise matched value. The controller continuously monitors the actual power transfer efficiency and automatically adjusts the resonator's frequency to maintain optimal performance. This dynamic adaptation allows the system to compensate for frequency drift caused by environmental changes, component tolerances, or temperature variations, thereby maintaining both high efficiency and reliability without requiring extremely precise initial frequency matching.
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 effectively limits output voltage to below 5V and power dissipation to below 1W across a range of frequencies, reducing the risk of overheating and component damage while maintaining efficient power transfer.
Implementation Method 1
a receiver resonator (112) arranged to inductively generate alternating current power from a transmitter (102)
Implementation Method 2
a rectifier (114) arranged to convert the alternating current power to a direct current power
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A wireless electrical power receiver (104) for inductively generating alternating current power in a wireless electrical power transfer system (100) having a transmission resonant frequency, the receiver (104) comprising a receiver resonator (112) having a receiver resonant frequency, the receiver resonator (112) constructed and arranged such that the receiver resonant frequency is detuned from the transmission resonant frequency.