LC Oscillating Circuit for Wireless Power Q-Factor Detection
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Solution Overview
Problem
Current methods for measuring the Quality Factor (Q-Factor) in wireless power systems are complex and prone to errors, particularly due to instability in input voltage and high current requirements, which affects the accuracy and efficiency of foreign object detection and resonant frequency determination.
Innovation Solution
A wireless power transmitter with a measurement circuit that forms an LC oscillating circuit using a transmit coil and capacitor, allowing for the determination of Q-Factor through monitoring a sinusoidal voltage, enabling efficient detection of foreign objects and improving measurement stability and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Q-Factor measurement methods are used, then measurement can be performed, but the measurement process becomes complex and prone to errors due to input voltage instability and high current requirements
Solution Approach 1:
The patent extracts the Q-Factor measurement function from the complex traditional measurement system by forming a dedicated LC oscillating circuit using the transmit coil and capacitor. This separate oscillating circuit allows for simplified measurement that is less dependent on input voltage stability and high current requirements, thereby reducing measurement complexity while maintaining accuracy.
Solution Approach 2:
The patent introduces an intermediary LC oscillating circuit as a mediator between the power transmission system and the Q-Factor measurement process. This oscillating circuit, formed by the transmit coil and capacitor, serves as an intermediate stage that converts the complex power system parameters into a simpler sinusoidal voltage signal that is easier to measure accurately without requiring stable input voltage or high currents.
2Productivity
If traditional measurement methods are used, then Q-Factor can be determined, but measurement time is increased and foreign object detection efficiency is reduced
Solution Approach 1:
The patent performs preliminary action by forming the LC oscillating circuit and measuring the sinusoidal voltage before the actual power transmission begins. The Q-Factor is determined in advance through this pre-configured oscillating circuit, allowing for rapid foreign object detection without requiring time-consuming traditional measurement procedures during operation.
Solution Approach 2:
The patent changes the measurement parameter from direct power system measurements (which require stable voltage and high current) to measuring the sinusoidal voltage of the LC oscillating circuit. This parameter change enables faster measurement that is less sensitive to system conditions, thereby reducing measurement time and improving foreign object detection efficiency.
3Reliability
If traditional Q-Factor measurement is performed, then measurement can be completed, but the measurement is highly dependent on input voltage stability
Solution Approach 1:
The patent extracts the measurement function from the input voltage-dependent traditional method by creating a separate LC oscillating circuit. This extracted measurement approach uses the inherent properties of the transmit coil and capacitor to generate a sinusoidal voltage that is independent of input voltage fluctuations, thereby improving measurement stability while reducing dependency on voltage stability.
Solution Approach 2:
The LC oscillating circuit performs self-service by generating its own sinusoidal voltage signal through the natural resonance of the transmit coil and capacitor combination. This self-generated signal is inherently stable and does not require external voltage stabilization, allowing the measurement to be reliable even when input voltage varies.
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 proposed solution provides a more stable and accurate measurement of Q-Factor, reducing measurement time and complexity, while being less dependent on input voltage stability, thus enhancing foreign object detection and resonant frequency determination in wireless power systems.
Implementation Method 1
the transmit driver configures the half bridge circuit to form an LC oscillating circuit with the transmit coil and the capacitor circuit, monitors a sinusoidal voltage in the LC oscillating circuit
Implementation Method 2
a transmitter coil that is driven to produce a time-varying magnetic field and a receiver coil that is positioned relative to the transmitter coil to receive the power transmitted in the time-varying magnetic field
Data Source
AI summary
A wireless transmitter with Q-factor measurement is presented. In some embodiments, a method of performing a measurement test in a wireless power transmitter includes adjusting an input voltage to a bridge circuit; setting up transistors in the wireless power transmitter to form an LC oscillating circuit that includes a transmit coil and a capacitor circuit; measuring a VDET sinusoidal voltage from the LC oscillating circuit; and determining a result from the VDET sinusoidal voltage. The result can be calculation of a Q-factor and/or determination of presence of a foreign object.