Resonance Frequency Detection Using PLL Phase Error Correction
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Solution Overview
Problem
Existing resonance frequency detectors face challenges in accurately following temporal changes in resonance frequency due to environmental conditions, leading to frequency errors and decreased detection accuracy of physical quantities.
Innovation Solution
A resonance frequency detector that adds a correction term to the oscillation frequency based on phase errors and the rate of phase change, using a phase locked loop to generate a control signal and correct for frequency deviations, ensuring accurate resonance frequency detection even when environmental conditions change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a phase locked loop is used to perform feedback control of the oscillation frequency, then the oscillation frequency can follow the resonance frequency changes, but a frequency error still occurs between the oscillation frequency and the resonance frequency
Solution Approach 1:
The patent replaces the conventional phase locked loop feedback control mechanism with a frequency calculation based on phase difference measurements. Instead of using feedback control to adjust oscillation frequency, the system calculates the resonance frequency directly from the phase difference between the oscillation signal and resonance element output signal, thereby eliminating frequency errors inherent in feedback control systems.
2Stability of the object's composition
If feedback control is applied to maintain oscillation frequency, then frequency stability can be maintained, but the detected resonance frequency includes errors that decrease physical quantity detection accuracy
Solution Approach 1:
The patent introduces a phase difference calculation as an intermediary measurement between the oscillation frequency control and the resonance frequency detection. By measuring the phase difference between the oscillation signal and the resonance element output signal, and using this phase difference to calculate the resonance frequency, the system achieves accurate resonance frequency detection without being affected by feedback control errors.
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 allows for precise tracking of resonance frequency changes, enhancing the accuracy of physical quantity detection by canceling frequency errors and maintaining followability with environmental variations.
Implementation Method 1
a phase locked loop that generates a control signal based on a phase error between an output signal of the resonance element that resonates at the resonance frequency and an output signal of the oscillator that varies the oscillation frequency according to the control signal
Implementation Method 2
an output signal of the resonance element that resonates at the resonance frequency
Data Source
AI summary
A resonance frequency detector has an adder that adds a correction term to an oscillation frequency of an output signal of an oscillator, and detects a predetermined resonance frequency of a resonance element. The correction term is generated based on a phase error in a phase locked loop and a degree of change in phase at the resonance frequency, and the phase locked loop generates a control signal based on the phase error between an output signal of the resonance element that resonates at the resonance frequency and the output signal of the oscillator that varies the oscillation frequency according to the control signal.