Plasma Torch Power Circuit Cooling via Cold Plate
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Solution Overview
Problem
Existing plasma cutting systems require numerous hardware components, leading to significant bulk and design complexity, which results in inefficient power supply performance in terms of power output per unit mass and volume, as well as higher average case temperatures during operation.
Innovation Solution
The proposed solution reduces the number of components by using two IGBTs instead of four, four DC bus capacitors instead of eight, three power resistors instead of six, zero fans, one cold plate instead of two heat sinks, and one PCB assembly instead of four, incorporating a multi-pulse transformer and interleaved chopper operation to improve cooling and power performance, while maintaining or exceeding power quality standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If numerous hardware components (four IGBTs, eight DC bus capacitors, six power resistors, four fans, two heat sinks) are used in the power circuit, then the system can provide sufficient cooling and power handling, but the bulk, design complexity, and component count increase significantly
Solution Approach 1:
The patent consolidates multiple cooling functions into a single cold plate that simultaneously cools multiple power components (IGBTs, diodes, resistors) through integrated mounting surfaces and thermal pathways, eliminating the need for separate heat sinks and reducing overall system complexity while maintaining adequate thermal management
Solution Approach 2:
The cold plate serves multiple functions: it acts as a thermal management device for power components, provides structural mounting support, and integrates fluid distribution channels for coolant flow. This multi-functionality replaces several dedicated components with a single versatile structure
2Power
If numerous hardware components are used in the power circuit, then sufficient power handling capacity is achieved, but the power output per unit mass and volume decreases
Solution Approach 1:
The patent merges multiple power handling functions into fewer components by using interleaved chopper configurations where two choppers share a common DC bus capacitor bank, and by integrating power resistors directly onto the cold plate structure, thereby reducing total component mass while maintaining required power handling capacity
Solution Approach 2:
The patent changes the operational parameters by implementing interleaved switching modes for the choppers, which allows for reduced ripple current and enables the use of smaller, lighter capacitor and inductor components while maintaining stable power delivery, thus improving power density
3Reliability
If numerous hardware components are used in the power circuit, then sufficient cooling is provided, but the average case temperature of the power supply increases
Solution Approach 1:
The cold plate integrates multiple cooling pathways and thermal contact surfaces into a single unified structure that distributes coolant flow more efficiently across all power components, reducing thermal resistance and lowering average case temperatures compared to separate heat sink arrangements
Solution Approach 2:
The cold plate acts as an intermediary thermal management device that provides direct thermal coupling between multiple power components and the coolant flow path, enabling more effective heat extraction and lower operating temperatures than indirect cooling methods
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 achieves greater power output per unit mass and volume while maintaining a lower average case temperature, reducing the size and weight of the power supply, and improving cooling efficiency, thus addressing the bulk and complexity issues of existing systems.
Implementation Method 1
The cold plate can improve cooling of the power supply
Implementation Method 2
a fluid conduit disposed within the cold plate... configured to direct a coolant fluid through the conduit
Implementation Method 3
a multi-pulse transformer is used... can help to meet or exceed power quality standards as defined by power factor benchmarks and benchmarks for total harmonic distortion (THD) of input current
Implementation Method 4
the choppers operate in an interleaved mode. Operating in interleaved mode using a single bank of capacitors can result in a significant reduction in the capacitor ripple current. Interleaved operation of the choppers can enable input and/or output ripple current cancellation
Implementation Method 5
the multi-pulse transformer is connected to a series connection of two three-phase diode bridges. Connecting the multi-pulse transformer to a series connection of two three-phase diode bridges can enable a reduction in ripple current ratings of the capacitor
Data Source
AI summary
A plasma arc cutting system includes a power supply comprising a multi-pulse transformer and a plurality of semiconductor switches directly connected to a bank of capacitors, and a thermal regulation system connected to the power supply and configured to cool the multi-pulse transformer. The thermal regulation system includes a cold plate in direct contact with the semiconductor switches; a fluid conduit disposed within the cold plate; and a pump connected to the conduit and configured to direct a coolant fluid through the conduit. The power supply has at least one of the following operating requirements: (i) a weight to power ratio of approximately 22.4 pounds per kilowatt; (ii) a volume to power ratio of approximately 1366 cubic inches per kilowatt; (iii) an average semiconductor device case temperature of approximately 100 degrees Centigrade during a cutting operation; (iv) a maximum transformer temperature of about 133 degrees Centigrade during a cutting operation.