Cryocooler Adaptive Phase Control for Harmonic Vibration Cancellation
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Solution Overview
Problem
Stirling cycle cryogenic coolers generate vibrations due to moving components, which can limit the performance of sensors and communication systems in spacecraft, and existing adaptive feed-forward vibration control systems do not effectively cancel these vibrations, especially at higher harmonics.
Innovation Solution
The implementation of adaptive phase control (APC) in the active vibration cancellation process, which involves identifying the magnitude and phase angle of vibration forces, determining a cancellation force vector, and adjusting the phase angle of the command signal to cancel residual harmonic vibrations, thereby improving vibration cancellation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive feed-forward vibration control is implemented to cancel vibrations at fundamental frequency, then vibration cancellation at fundamental frequency is improved, but vibration cancellation at higher harmonics deteriorates
Solution Approach 1:
The system dynamically adjusts the phase angle of the command signal based on real-time identification of vibration forces at different frequencies. The phase angle is not fixed but adapts to the specific frequency characteristics being targeted, allowing the same control mechanism to effectively cancel vibrations across multiple frequency ranges including both fundamental frequency and higher harmonics
Solution Approach 2:
The invention changes the phase angle parameter of the command signal to target different frequency components. By identifying the frequency of dominant vibration forces and adjusting the phase angle accordingly, the system can shift its cancellation effectiveness from fundamental frequency to higher harmonics, thus expanding the frequency range coverage
2Device complexity
If the command signal phase angle is fixed, then the control system is simple, but it cannot effectively cancel vibrations at varying frequencies
Solution Approach 1:
The system uses feedback from vibration sensors to identify the magnitude and frequency of vibration forces in real-time. This feedback information is then used to adjust the phase angle of the command signal, creating a closed-loop control system that adapts to varying vibration frequencies while maintaining relatively simple hardware architecture
Solution Approach 2:
The control system automatically identifies vibration characteristics and adjusts its own phase angle parameter without external intervention. The system serves itself by using its own vibration output as the basis for adjusting its control parameters, enabling frequency adaptation through self-tuning
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 adaptive phase control significantly reduces vibrations at multiple frequencies, enhancing the performance of cryogenic coolers by effectively canceling both fundamental and harmonic vibrations, leading to improved stability and efficiency in cryogenic cooling systems.
Implementation Method 1
a Stirling cycle cryogenic cooler system can include piezoelectric force transducers that sense physical vibrations that the cryocooler creates and that generate electrical output signals corresponding to the sensed vibrations
Implementation Method 2
a piston assembly includes a wire coil wound around a bobbin that annularly surrounds the shaft portion of the piston; the piston assembly sits in a magnetic field, and upon receiving current through the coil, an electromagnetic force drives the piston in a linear motion
Data Source
AI summary
A method includes identifying a magnitude and phase angle of vibration forces resulting from a previous cancellation signal, where a first measured force vector is defined by this magnitude and phase angle. The method also includes identifying a magnitude and phase angle of a first cancellation force and transmitting a first AFF cancellation signal configured to generate the first cancellation force, where a first cancellation force vector is defined by this magnitude and phase angle. The method further includes identifying a magnitude and phase angle of vibration forces resulting from the first AFF cancellation signal, where a first resultant force vector is defined by this magnitude and phase angle. Moreover, the method includes determining whether a phase angle difference between the phase angles of the first resultant force vector and the first measured force vector is substantially equal to zero. If so, the method includes continuing to transmit the first AFF cancellation signal.