X-ray tube rotor speed control via PMSM deceleration
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Solution Overview
Problem
X-ray tubes face challenges with high centrifugal loads and abrasive contact in bearing assemblies due to high rotational speeds, leading to reduced component lifespan and image quality issues.
Innovation Solution
Implementing a permanent magnet synchronous motor (PMSM) with integrated thermal barriers and precise speed and position monitoring to minimize rotor losses, reduce heat generation, and control deceleration profiles, thereby reducing abrasive contact and extending component life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is decelerated to a halt, then rubbing between the shaft and the sleeve of the bearing assembly is reduced, but the rotor must pass through positions where gravitational pull exceeds the applied force
Solution Approach 1:
The rotor is decelerated to a halt before being subjected to full gravitational load during position changes. By pre-positioning the rotor at optimal locations and allowing it to stop completely before moving to the next position, the bearing assembly experiences minimal rubbing and wear during deceleration phases, extending its operational lifespan
Solution Approach 2:
The system operates by moving the rotor between discrete positions where it can be held stationary, creating equipotential states where gravitational forces are balanced or minimized. This approach ensures that the rotor only experiences significant gravitational forces when stationary at predetermined positions, rather than during continuous motion
2Manufacturing precision
If the rotor speed and position are accurately monitored, then image quality is enhanced, but the system complexity increases
Solution Approach 1:
The system incorporates sensors and control circuits that continuously monitor rotor speed and position, providing real-time feedback to the control system. This feedback mechanism enables precise adjustment of rotor deceleration and positioning, ensuring consistent image quality while automating the control process to manage system complexity
Solution Approach 2:
The patent replaces complex mechanical positioning mechanisms with electronic monitoring and control systems. By using sensors, microprocessors, and software algorithms to track and adjust rotor position and speed, the system achieves high precision image quality without requiring overly complex mechanical structures
3Reliability
If the rotor is decelerated using a predefined profile, then rubbing between shaft and sleeve is minimized, but the deceleration process takes time
Solution Approach 1:
The rotor deceleration follows a periodic, predefined profile that cycles through specific speed reduction phases. By implementing regular deceleration patterns at predetermined intervals and positions, the system minimizes bearing wear through consistent controlled stopping while optimizing the time required for each deceleration cycle
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 PMSM reduces input current demand, decreases stator and electronic losses, and enhances image quality by allowing precise control of rotor speed and position, prolonging the useful life of the x-ray tube and reducing maintenance.
Implementation Method 1
An induction motor may be employed to rotate the anode, the induction motor having a cylindrical rotor
Implementation Method 2
rubbing between the shaft and the sleeve of a bearing assembly is circumvented or at least decreased
Data Source
AI summary
Various methods and systems are provided for an x-ray imaging system. In one example, a method for decelerating a rotor of an x-ray tube of an imaging system includes controlling and/or monitoring a speed and position of the rotor, passing the rotor through a first position where a force exerted on the rotor, is less than Earth's gravitational pull, the force due to a combination of gravity and radial acceleration, and initiating a predefined deceleration profile to decelerate the rotor to a halt when the x-ray tube passes through the first position.