Power electronics system, electrical system, and propulsion system for a vehicle such as an aircraft
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Solution Overview
Problem
There is a need to improve the integration and cooling of power electronics systems in vehicles, particularly in aircraft, as they are increasingly electrical in nature and require specialized cooling solutions, especially for systems using cryogenic liquid hydrogen or high-power fuel cells.
Innovation Solution
A power electronics system with a cryogenic cooling loop and a controller that adjusts coolant flow based on electrical properties of power switching elements to minimize drain-source resistance and maintain optimal junction temperature, using cryogenic temperatures to enhance semiconductor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional cooling systems are used for power electronics, then the system can operate, but the power density and efficiency are limited due to thermal constraints
Solution Approach 1:
The patent changes the temperature parameter from conventional operating temperatures to cryogenic temperatures (below 100K, preferably below 20K). This parameter change fundamentally alters the thermal and electrical characteristics of the power semiconductor devices, enabling higher power density and efficiency by reducing thermal noise and improving carrier mobility in the semiconductor material.
Solution Approach 2:
The control system periodically adjusts the coolant flow rate based on real-time monitoring of electrical properties and temperature conditions. This periodic control allows the system to maintain optimal operating parameters while adapting to varying load conditions, ensuring consistent high performance without continuous thermal stress.
2Power
If multiple power switching elements are connected in parallel to increase current capacity, then the current handling capability improves, but the drain-source resistance increases and control complexity increases
Solution Approach 1:
The control system continuously monitors the electrical properties of each power switching element and uses this feedback to dynamically adjust the coolant distribution. This feedback mechanism ensures that each device operates within optimal parameters, maintaining low drain-source resistance even when multiple devices are connected in parallel, thereby improving overall system reliability.
Solution Approach 2:
The system applies localized cooling to each power switching element based on its individual thermal and electrical conditions. By controlling coolant flow to specific devices rather than using uniform cooling, the system optimizes the performance of each parallel-connected element, minimizing individual drain-source resistances and ensuring balanced current distribution.
3Loss of energy
If cryogenic cooling is applied to reduce drain-source resistance, then the electrical efficiency improves, but the system complexity and cooling requirements increase
Solution Approach 1:
The cryogenic cooling system serves multiple functions simultaneously: it cools the power electronics to reduce drain-source resistance, it provides a stable operating environment for high-frequency switching, and it enables the use of advanced semiconductor materials that require low temperatures for optimal performance. This multi-functionality justifies the increased system complexity by delivering multiple performance benefits from a single integrated solution.
Solution Approach 2:
The cooling system is designed with dynamic control capabilities, allowing the coolant flow rate and temperature to be adjusted in real-time based on the operational demands of the power electronics. This dynamic adaptation enables the system to maintain optimal electrical efficiency across varying load conditions while managing the complexity through intelligent control rather than static over-engineering.
4Temperature
If the coolant flow rate is increased to improve cooling, then the temperature control improves, but the system loses cryogenic coolant and energy efficiency decreases
Solution Approach 1:
The control system implements periodic adjustment of the coolant flow rate rather than continuous maximum flow. By monitoring thermal conditions and electrical properties in real-time, the system activates cooling only when and where needed, maintaining effective temperature control while minimizing overall coolant consumption and associated energy losses.
Solution Approach 2:
The system applies cooling locally to specific power switching elements that require it based on their individual thermal conditions and electrical performance. This localized approach ensures effective temperature control for devices operating under stress while avoiding unnecessary cooling of devices that are already within optimal parameters, thereby reducing total coolant loss and improving energy 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 approach increases power density, reduces weight and volume, and improves reliability by optimizing semiconductor operation and reducing thermal cycling, while being compatible with various semiconductor technologies.
Implementation Method 1
a cryogenic cooling loop configured for cooling the power electronics circuit, the cryogenic cooling loop having a heat exchanger that is in thermal contact with the power electronics circuit
Implementation Method 2
a heat exchanger that is in thermal contact with the power electronics circuit
Implementation Method 3
a control valve configured for controlling coolant flow within the cryogenic cooling loop, the control valve arranged to control the coolant flow to the heat exchanger
Implementation Method 4
the controller is configured to control the control valve based on the electrical property of drain-source resistance of each power switching element such that the drain-source resistance is reduced or minimized
Data Source
AI summary
Use of cryogenic fuel tanks for the cooling of power electronics circuits to improve cooling capabilities for power electronics in vehicles or an aircraft. The power electronics circuit can be cooled via a cryogenic cooling loop by the fuel directly, or the fuel is used to cool a separated coolant tank. A control valve controls the coolant flow within the cryogenic cooling loop based on an electrical property of the power switching element of the power electronics circuit and or based on the way the power switching elements are electrically connected together. The control valve can control the coolant flow such that a junction temperature is achieved which minimizes the drain-source resistance.