Phase Detection Circuit for Wireless Power Measurement
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Solution Overview
Problem
Measuring high-frequency AC power and load impedance in wireless power transfer systems is challenging due to the need for precise and accurate measurements across a large impedance range, which existing systems fail to provide efficiently and accurately.
Innovation Solution
The system determines a phase difference between time-varying voltage and current signals using a phase detection circuit and selectively couples a current source to a capacitor based on the phase signal, allowing for improved power and impedance measurement through a phase offset detection method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AC power measurement systems are used, then basic power measurement is achieved, but measurement precision and accuracy at high frequencies and large impedance ranges deteriorate
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring voltage and current separately using dedicated sensing circuits, then calculating power through phase difference computation. This intermediary step of separate measurement and mathematical processing enables accurate high-frequency power measurement without directly measuring power at those frequencies, thus resolving the measurement difficulty while maintaining precision
Solution Approach 2:
The patent replaces conventional direct power measurement mechanisms with a computational approach using phase detection circuits and digital signal processing. By substituting direct mechanical/electrical power measurement with a system that measures voltage and current separately and computes power through phase difference, the system achieves accurate high-frequency measurements that conventional direct methods cannot provide
2Measurement precision
If phase offset detection method is implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges the voltage sensing circuit, current sensing circuit, phase detection circuit, and power calculation functions into an integrated measurement system. By combining these previously separate functions into a unified circuit architecture, the system achieves precise phase difference measurement while reducing overall device complexity through functional integration
Solution Approach 2:
The patent designs the measurement circuit to perform multiple functions: voltage sensing, current sensing, phase detection, and power calculation. This multi-functional approach eliminates the need for separate dedicated circuits for each measurement task, thereby improving measurement precision while keeping the overall device complexity manageable through universal circuit design
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 enables precise and accurate measurement of AC power and load impedance, enhancing foreign object detection, load management, and efficiency control in wireless power transfer systems.
Implementation Method 1
a capacitor configured to receive a current from a current source for the duration of the phase offset between the time-varying voltage and a time-varying current
Data Source
AI summary
The invention provides a method and system for precisely measuring AC power and detecting load impedance using a precise analog front-end, zero-crossing detectors, and a phase detection system capable of extracting precise phase information from the sensed voltage and current measurements. More particularly, the invention provides an apparatus, comprising a transmit circuit configured to generate a wireless field via an antenna for transferring charging power to a receiver device, for determining a phase difference between a first signal and a second signal. The apparatus further comprises a phase detection circuit to output a phase signal indicating a duration of a phase offset between a time-varying voltage and a time-varying current of the transmit circuit. The apparatus further comprises a capacitor configured to receive a variable current from a current source for the duration of the phase offset between the time-varying voltage and a time-varying current.