Phase-Locked Loop Resonance Tracking With Environmental Correction
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Solution Overview
Problem
Existing phase locked loops struggle to accurately maintain the oscillation frequency in sync with changing resonance frequencies due to environmental conditions like temperature, leading to frequency errors that degrade the detection accuracy of physical quantity sensors.
Innovation Solution
A phase locked loop configuration that includes an oscillator, a resonance element, a phase detector, a feedback controller, and a control signal corrector. The control signal corrector adds a correction term based on environment information to the control signal from the feedback controller, ensuring the oscillation frequency follows the resonance frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to adjust oscillation frequency according to resonance frequency changes, then the oscillation frequency can follow resonance frequency variations, but frequency error still occurs due to practical difficulties in accurate frequency adjustment
Solution Approach 1:
The patent employs a phase-locked loop feedback mechanism where the phase detector continuously compares the phase of the resonance element output signal with the oscillator output signal, and the feedback controller adjusts the oscillator frequency based on the detected phase error. This closed-loop feedback system enables automatic frequency tracking that compensates for environmental variations, resolving the contradiction between frequency tracking capability and detection precision.
Solution Approach 2:
The patent replaces traditional mechanical or simple electronic frequency adjustment mechanisms with a phase-based feedback control system. By using phase detection and electronic feedback control instead of direct mechanical frequency tuning, the system achieves more precise and stable frequency tracking, thereby improving both frequency accuracy and physical quantity detection precision.
2Stability of the object's composition
If the oscillation frequency is adjusted to follow resonance frequency changes, then frequency synchronization is improved, but phase error persists due to practical limitations in frequency adjustment accuracy
Solution Approach 1:
The phase-locked loop uses continuous phase error detection and feedback control to maintain frequency synchronization. The phase detector monitors the phase difference between oscillator and resonance element signals, and the feedback controller continuously adjusts the oscillator frequency to minimize phase error, achieving stable frequency synchronization with high precision despite environmental variations.
Solution Approach 2:
The patent changes the control parameter from direct frequency adjustment to phase error-based feedback control. By controlling the oscillator through phase error signals rather than direct frequency commands, the system achieves more precise frequency synchronization and reduces phase error, resolving the contradiction between synchronization stability and measurement precision.
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 solution effectively reduces the phase error caused by environmental changes, allowing for more accurate detection of physical quantities without dependency on environment information.
Implementation Method 1
a resonance element that resonates at a predetermined resonance frequency and output a signal obtained by shifting a phase of an output signal of the oscillator by 90 degrees at the resonance frequency
Implementation Method 2
a phase detector that detects a phase error between an output signal of the resonance element and an output signal of the oscillator
Implementation Method 3
a feedback controller that controls a frequency of an output signal of the oscillator by proportional control and integral control according to the phase error
Implementation Method 4
a control signal corrector that corrects the control signal by adding a correction term corresponding to environment information to an output signal of the feedback controller
Data Source
AI summary
A phase locked loop has an oscillator that varies a frequency according to a control signal, a resonance element that resonates at a predetermined resonance frequency and output a signal obtained by shifting a phase of an output signal of the oscillator by 90 degrees at the resonance frequency, a phase detector that detects a phase error between an output signal of the resonance element and an output signal of the oscillator, a feedback controller that controls a frequency of an output signal of the oscillator by proportional control and integral control according to the phase error, and a control signal corrector that corrects the control signal by adding a correction term corresponding to environment information to an output signal of the feedback controller.