Wireless Power Amplifier Impedance Detection via Negative Voltage Sensing
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Solution Overview
Problem
Magnetic resonance type wireless power transmission systems are susceptible to efficiency loss and power amplifier damage due to changes in resonant frequency caused by external factors, particularly when input impedance becomes capacitive, and existing detection methods increase cost and board size.
Innovation Solution
A negative voltage detection circuit is integrated into the wireless power transmission device, comprising a voltage dividing circuit, a low-pass filter, and a voltage sensor to convert negative voltages into positive voltages for detection, allowing for efficient impedance monitoring without increasing size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase detector and directional coupler are used to detect impedance changes, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential detection function needed for impedance monitoring. Instead of using complex phase detectors and directional couplers, it isolates the core requirement (detecting capacitive input impedance) and implements a simplified circuit that performs only this specific function, removing unnecessary complexity while maintaining detection capability
Solution Approach 2:
The patent replaces expensive, complex detection components with inexpensive, simple circuit elements. The simplified detection circuit uses basic components that are cheaper and easier to implement than phase detectors and directional couplers, achieving the same detection purpose with lower cost and complexity
2Measurement precision
If phase detector and directional coupler are used to detect impedance changes, then detection accuracy is improved, but board size increases
Solution Approach 1:
The patent extracts only the essential detection function needed for impedance monitoring. Instead of using complex phase detectors and directional couplers, it isolates the core requirement (detecting capacitive input impedance) and implements a simplified circuit that performs only this specific function, removing unnecessary complexity while maintaining detection capability
Solution Approach 2:
The patent merges the detection function with existing circuit elements or integrates it into the power amplifier circuitry. By combining the detection circuit with other existing components or structures, it eliminates the need for separate dedicated detection hardware, thereby reducing overall board space occupation
3Length of moving object
If magnetic resonance method is used for wireless power transmission, then transmission distance is improved, but system reliability deteriorates when resonant frequency changes
Solution Approach 1:
The patent implements a feedback mechanism where the detection circuit continuously monitors the input impedance of the power amplifier and provides information about capacitive loading conditions. This feedback enables the system to detect changes in resonant frequency caused by external factors and take appropriate actions to maintain reliable operation
Solution Approach 2:
The patent applies preliminary protective measures by detecting capacitive input impedance conditions before they cause damage to the power amplifier. The detection circuit identifies early signs of resonant frequency drift and capacitive loading, allowing the system to take preventive actions (such as adjusting operating parameters or shutting down) before reliability is compromised
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 detects capacitive input impedance, preventing power amplifier damage and maintaining system efficiency while being compact and cost-effective.
Implementation Method 1
a voltage dividing circuit including a positive voltage power supply and a plurality of resistors, the voltage dividing circuit being configured to convert the negative voltage generated in the filter circuit of the power amplifier circuit into a positive voltage in a predetermined range
Implementation Method 2
a low-pass filter located between and connected to the voltage dividing circuit and the voltage sensor
Implementation Method 3
a voltage sensor configured to detect the positive voltage
Implementation Method 4
a power amplifier circuit including a switch circuit, a filter circuit, and a series resonant circuit, the power amplifier circuit being configured to convert direct current (DC) power received from the battery or a DC adapter into alternating current (AC) and to implement zero-voltage switching (ZVS)
Implementation Method 5
The magnetic resonance type wireless power transmission device may include a class EF2 power amplifier (PA). The class EF2 power amplifier may reduce the switching loss caused by voltage and current overlap by using the zero-voltage switching (ZVS) method, which is a soft switching technology.
Implementation Method 6
a power transmission circuit including a power transmission coil configured to transmit power received from the power amplifier circuit to outside
Data Source
AI summary
An electronic device is provided. The electronic device includes a processor, a battery, and a wireless power transmission device, wherein the wireless power transmission device includes a power amplifier circuit including a switch circuit, a filter circuit, and a series resonant circuit, the power amplifier circuit being configured to convert direct current (DC) power received from the battery or a DC adapter into alternative current (AC) and to implement zero-voltage switching (ZVS), a power transmission circuit including a power transmission coil configured to transmit power received from the power amplifier circuit to outside, a matching circuit located between and connected to the power amplifier circuit and the power transmission circuit, the matching circuit being configured to match an impedance of the power amplifier circuit and the power transmission circuit, and a negative voltage detection circuit connected to the filter circuit of the power amplifier circuit and configured to detect a negative voltage generated in the filter circuit, and wherein the negative voltage detection circuit includes a voltage dividing circuit including a positive voltage power supply and a plurality of resistors, the voltage dividing circuit being configured to convert the negative voltage generated in the filter circuit of the power amplifier circuit into a positive voltage in a predetermined range, a voltage sensor configured to detect the positive voltage, and a low-pass filter located between and connected to the voltage dividing circuit and the voltage sensor.