X-ray Source Arrangement with Pre-Controller for Flat-Top Pulse Generation
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Solution Overview
Problem
Conventional X-ray sources face challenges in generating reproducible high-voltage pulses with a flat-top pulse shape, which is essential for medical imaging applications, due to difficulties in controlling the converter's output voltage and current effectively.
Innovation Solution
An X-ray source arrangement that includes a pre-controller and a modulator, which use a mathematical model of the resonant converter to determine a reference duty ratio and generate a control signal for the inverter, ensuring stable and well-defined voltage pulses are produced by the converter, thereby improving the output characteristic of the X-ray tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional feedback loop with proportional and integral parts is used to control the converter output voltage, then the system can compensate for deviations, but it becomes difficult to generate reproducible high-voltage pulses with a flat-top pulse shape
Solution Approach 1:
The patent applies preliminary action by pre-calculating the duty ratio trajectory using a mathematical model of the resonant converter before the actual control process. The pre-controller computes the optimal duty ratio profile that will produce the desired flat-top voltage pulse, eliminating the need for complex real-time feedback adjustments and enabling precise pulse shape control from the outset.
2Speed
If the rise time of the voltage pulse is reduced to improve imaging response, then the imaging speed increases, but overshoot occurs which degrades pulse quality
Solution Approach 1:
The patent employs parameter changes by dynamically adjusting the duty ratio parameter according to a pre-calculated trajectory. The mathematical model determines the optimal duty ratio profile that achieves the desired rise time while preventing overshoot, allowing the system to optimize pulse characteristics by varying the duty ratio in a controlled manner throughout the pulse generation 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 solution enables the generation of stable, reproducible high-voltage pulses with a flat-top shape, reducing overshoot and achieving the shortest possible rise time, thus enhancing the output characteristic of the X-ray source and improving medical imaging capabilities.
Implementation Method 1
a converter with an inverter coupled to a resonant converter, also referred to as resonant tank
Implementation Method 2
the inverter may e.g. comprise a half-bridge and/or a full-bridge module for supplying electrical power to the resonant tank
Implementation Method 3
By means of the converter, a certain output voltage and/or a certain output current may be supplied to an X-ray tube, such that X-ray radiation of a certain energy and/or intensity may be generated
Data Source
AI summary
An X-ray source arrangement (10) for generating X-ray radiation (102), a method for operating the X-ray source arrangement (10), and an X-ray imaging apparatus (100) are provided. The X-ray source arrangement (10) comprises an X-ray tube (22), a converter arrangement (16) with an inverter (18) and a resonant converter (20) for providing a source voltage to the X-ray tube (22), a pre-controller (12), and a modulator (14). The pre-controller (12) is configured for determining a reference duty ratio (r, 26) of the resonant converter (20) as a continuous function of time based on a mathematical model of the resonant converter (20), and for providing a control signal (13) correlating with the reference duty ratio (r, 26) to the modulator (14). The modulator (14) is configured for determining a switching signal (15) based on the control signal (13), and for providing the switching signal (15) to the inverter (18) of the converter arrangement (16) for actuating the inverter (18).