Dynamic Damper Frequency-Dependent Impedance X-Ray Tube
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Solution Overview
Problem
Conventional CT X-ray imaging systems face issues with unstable X-ray tube operating voltages and slow voltage switching times, leading to reduced fidelity in material characterization due to variations in effective mean energy of the X-ray spectrum, and temporary electrical short-circuits known as 'tube-spit' that disrupt data acquisition.
Innovation Solution
A dynamic damper with frequency-dependent impedance is introduced between the X-ray tube and the high voltage generator, providing a high impedance during high-frequency tube-spit events while maintaining low impedance during normal operation, combined with a distributed resonant energy recovery circuit for efficient energy switching between voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed impedance damper is used to protect against tube-spit, then tube-spit protection is provided, but energy recovery efficiency is reduced due to continuous impedance blocking normal voltage switching
Solution Approach 1:
The patent applies a dynamic impedance damper whose impedance varies with frequency. During tube-spit events (high frequency), the damper presents high impedance to block harmful currents. During normal operation (low frequency), the damper presents low impedance to minimize energy loss. This dynamic adaptation resolves the contradiction between protection and efficiency.
Solution Approach 2:
The damper's impedance parameter is changed based on operating conditions. The impedance is high at tube-spit frequencies to provide protection, and low at normal operating frequencies to enable efficient energy recovery. This parameter change allows the system to optimize both protection and energy efficiency.
2Speed
If voltage switching speed is increased for rapid kV level transitions, then acquisition time is reduced, but voltage stability during integration period deteriorates
Solution Approach 1:
The system dynamically adjusts voltage switching characteristics. Rapid switching is enabled when needed for time efficiency, while voltage stability is maintained during integration periods through controlled switching timing. The dynamic damper supports this by providing frequency-dependent impedance that accommodates both fast transitions and stable operation.
Solution Approach 2:
The voltage switching operates in periodic cycles, with rapid transitions between kV levels followed by stable integration periods. This periodic action allows the system to alternate between speed-optimized phases and stability-optimized phases, resolving the contradiction between switching speed and voltage stability.
3Reliability
If conventional fixed impedance damper is used, then tube-spit protection is achieved, but voltage level switching between kV levels becomes inefficient due to continuous energy blocking
Solution Approach 1:
The dynamic damper adjusts its impedance characteristics based on the operating frequency. During voltage level switching (low frequency), the damper presents low impedance to enable efficient energy transfer and improve switching productivity. During tube-spit events (high frequency), it presents high impedance to provide protection. This dynamic behavior resolves the contradiction between protection and switching efficiency.
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 protects against tube-spit occurrences while enhancing energy recovery and fidelity in material characterization by maintaining stable voltage levels and efficient energy transfer, improving the overall performance of CT imaging systems.
Implementation Method 1
A dynamic damper with frequency-dependent impedance is introduced between the X-ray tube and the high voltage generator, providing a high impedance during high-frequency tube-spit events while maintaining low impedance during normal operation
Implementation Method 2
combined with a distributed resonant energy recovery circuit for efficient energy switching between voltage levels
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
In an X-ray generator 100 an X-ray tube 102 includes an anode 110 and a cathode 108 and is energized with at least a first high voltage potential. A dynamic damper 120 with a frequency dependent impedance is interposed between the X-ray tube and a source of the high voltage potential. The impedance of the dynamic damper 120 increases with an increase in frequency associated with tube-spit. The dynamic damper may be a solenoid. In an X-ray generator 100 with resonant switching to provide a first kV level and a second kV level to the X-ray tube 102, the impedance of the dynamic damper 120 is low at the operational frequency of the resonant switch to promote energy recovery when the resonant switch operates to provide a first kV level to the X-ray tube 102.