X-ray Inverter Switch MOSFET Layout
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Solution Overview
Problem
Existing X-ray tube power supply inverters face challenges in achieving high operating frequencies and short transient phases due to limited space for MOSFETs, necessitating the need for more compact and efficient switching solutions.
Innovation Solution
The design includes at least two MOSFETs aligned in parallel with intermediate radiators and snubbers positioned between them, a control unit, and damping devices, allowing for a more compact layout that increases the number of switches on a printed circuit while supporting high current and frequency operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MOSFETs are positioned side by side on a printed circuit to improve switching performance, then the operating frequency and transient phase performance improve, but the distance between MOSFETs increases (23 mm in prior art) which limits the number of switches that can be positioned on a printed circuit
Solution Approach 1:
The patent introduces intermediate radiators that extend in multiple dimensions to separate MOSFETs. The radiators have first portions between MOSFETs and second portions extending above the MOSFET alignment, utilizing three-dimensional space to achieve separation while maintaining compact footprint on the printed circuit board.
Solution Approach 2:
The intermediate radiators are nested within the overall switch assembly structure, with radiators positioned between MOSFETs and snubbers positioned beside MOSFETs, creating a compact nested arrangement that reduces the overall distance between components while maintaining necessary separation.
2Power
If MOSFETs are used for high-intensity current applications, then current capability improves, but normally IGBTs would be selected which operate at lower frequencies and generate substantial volume and cost of magnetic components
Solution Approach 1:
The patent changes the operating parameters by using MOSFETs instead of IGBTs, enabling operation at frequencies up to 300 kHz while handling currents greater than 500 peak amperes. This parameter change allows the system to achieve both high current capability and high operating frequency simultaneously.
3Reliability
If the number of MOSFETs is increased on a printed circuit to improve switching performance, then the current breaking capability improves, but the space requirements and thermal management challenges increase
Solution Approach 1:
The patent segments the thermal management function by introducing intermediate radiators between MOSFETs. These radiators provide dedicated thermal pathways for each MOSFET, allowing heat to be dissipated through multiple separate routes rather than requiring all heat to travel through a single common path, thereby improving thermal management 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 configuration enables the use of MOSFETs for high-intensity current and frequency applications, minimizes overvoltage, optimizes snubber capacitor volume, and enhances thermal dissipation and solderability, leading to improved performance and robustness in X-ray inverter switches.
Implementation Method 1
at least one intermediate radiator positioned between the MOSFETs in order to separate two successive MOSFETs
Implementation Method 2
a damping device positioned on one intermediate or extreme radiator face so as to maintain the contact between the MOSFET adjacent to this face with the following intermediate or extreme radiator
Data Source
AI summary
A switch of an inverter of an X-ray tube power supply including: at least four MOSFETs aligned in parallel; a plurality of intermediate radiators positioned between the MOSFETs in order to separate two successive MOSFETs; at least four snubbers positioned in parallel, each being positioned beside a MOSFET; a control unit of said switch positioned so that the succession of MOSFETs is positioned between the alignment of snubbers and the control unit.