Power Amplifier System for Wireless Power Transmitters
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Solution Overview
Problem
High-frequency wireless power transfer systems face efficiency reductions due to variable impedance loads caused by changes in coupling between coils and the presence of foreign objects, which existing technologies fail to effectively address.
Innovation Solution
A power amplifier system that employs a pulse-width modulator (PWM) to toggle switches between open and closed states based on load impedance, adjusting the duty cycle and output voltage to maintain efficient power transfer, coupled with a passive impedance transformation network to accommodate varying load impedances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a power amplifier drives the TX coil with high-frequency AC current in a resonant two-coil system, then wireless power transfer is enabled, but efficiency is reduced due to variable impedance load from coupling changes and foreign objects
Solution Approach 1:
The power amplifier system dynamically adjusts its operating parameters (duty cycle, output voltage) in real-time based on feedback from the variable impedance load. The controller continuously monitors load conditions and modifies the PWM duty cycle and power supply voltage to maintain optimal efficiency across changing coupling conditions and foreign object presence.
Solution Approach 2:
The system changes key operating parameters including the duty cycle of the PWM signal and the output voltage of the power supply to adapt to varying load impedance. By adjusting these parameters, the power amplifier maintains constant current output and optimal power transfer efficiency despite impedance variations caused by coupling changes or foreign objects.
2Loss of energy
If the PWM toggles switches to adjust duty cycle for varying load impedance, then power transfer efficiency is maintained, but device complexity increases
Solution Approach 1:
The controller performs multiple functions using a single integrated circuit: it monitors load impedance, generates PWM signals with adjustable duty cycle, regulates power supply output voltage, and maintains constant current output. This multi-functionality reduces the need for separate control components while achieving efficient power transfer across varying load conditions.
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 maintains efficient power transfer across a range of load impedances by dynamically adjusting the duty cycle and output voltage, ensuring a constant current output and reducing harmonic power, thereby improving the overall efficiency of wireless power transmission.
Implementation Method 1
a pulse-width modulator (PWM) coupled to the power amplifier, the PWM configured to substantially simultaneously toggle each of the first and second switches between open and closed states
Implementation Method 2
High frequency magnetic fields may be used to wirelessly provide power to a remote device. A typical implementation consists of a resonant two-coil system with a transmit (TX) coil and a receive (RX) coil.
Implementation Method 3
A typical implementation consists of a resonant two-coil system with a transmit (TX) coil and a receive (RX) coil
Implementation Method 4
High frequency magnetic fields may be used to wirelessly provide power to a remote device
Data Source
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AI summary
One example device for providing wireless power includes a power supply; a power amplifier coupled to the power supply, the power amplifier comprising a first switch and a second switch coupled to the power supply and to a common switch output, and a pulse-width modulator ("PWM") coupled to the power amplifier, the PWM configured to substantially simultaneously toggle each of the first and second switches between open and closed states, and to maintain the first and second switches in opposite open and closed states; a controller coupled to the power supply and the PWM, the controller configured to: receive a sensor signal indicating an impedance of a load; determine a duty cycle of the PWM based on the sensor signal; and adjust an output voltage of the power supply based on the duty cycle of the PWM.