Resonant Tank Q-Factor Determination via Transitory Damped Oscillations
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Solution Overview
Problem
Conventional DC-DC power converters using resonant tank networks face challenges in accurately measuring the Q-factor, which is crucial for ensuring proper operation, especially in applications like wireless charging where unexpected metal objects may be present, as existing methods lack efficient in situ measurement techniques.
Innovation Solution
A method and circuit design that excites transitory damped oscillations in the resonant tank network using a switch network and an electronic controller, allowing for the acquisition and processing of digital signal samples to determine the Q-factor, enabling repeated measurements to prevent unsuitable operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used for Q-factor, then measurement capability is limited, but measurement precision and ease of operation deteriorate
Solution Approach 1:
The resonant tank network measures its own Q-factor by utilizing its inherent oscillatory properties. The system excites the resonant tank and measures the decay of its natural oscillations, allowing the network to self-diagnose its Q-factor without requiring external specialized measurement equipment or complex procedures.
Solution Approach 2:
The Q-factor measurement is performed through periodic excitation of the resonant tank network. The system applies periodic pulses to excite oscillations and then measures the decay envelope over multiple cycles, using the periodic nature of the oscillations to accurately determine the Q-factor through envelope detection and analysis.
2Reliability
If in situ measurement is implemented, then operational safety is improved, but device complexity increases
Solution Approach 1:
The control circuit performs multiple functions: it controls the power switches for normal power conversion operation, generates excitation pulses for Q-factor measurement, and processes measurement signals. This multi-functionality allows in situ Q-factor measurement to be implemented without adding dedicated separate measurement hardware, thereby limiting the increase in device complexity.
Solution Approach 2:
The measurement functionality is merged with the existing power conversion circuitry. The same control circuit that manages power switch operation is used to initiate and process Q-factor measurements, and the resonant tank network serves both power conversion and measurement purposes, combining these functions into a unified system.
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
Enables accurate and repeated Q-factor determination, ensuring the resonant tank network operates optimally even in the presence of ambient factors like metal objects, thereby maintaining efficient power conversion and safety.
Implementation Method 1
exciting transitory damped oscillations of the resonant tank network
Implementation Method 2
Q-factor of a resonator is a dimensionless parameter that provides a measure of the strength of the damping of the resonator's oscillations
Data Source
AI summary
A power converter having a switch network, a resonant tank network, and a controller performs in situ determination of the Q-factor of the resonant tank network. The controller excites transitory damped oscillations of the resonant tank network by applying a limited number of ON-pulses to the transistor switches of the switch network. The controller then samples the envelope of the waveform corresponding to the excited transitory damped oscillations and processes the resulting set of digital signal samples to determine the Q-factor of the resonant tank network. The Q-factor determination can be repeated to prevent the power converter from being operated under undesirable operating conditions caused by certain ambient factors, such as the unexpected presence of metal objects in the immediate vicinity of the power converter.