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Advanced Thermal Management of Power Converters

Description:

RT&L FOCUS AREA(S): General Warfighting Requirements

TECHNOLOGY AREA(S): Electronics; Ground / Sea Vehicles

OBJECTIVE: Develop thermal management technologies to increase the power density of high-voltage power converters.

DESCRIPTION: Advanced sensors and effectors are driving shipboard power distribution systems toward higher voltages, resulting in greater thermal demands on the power conversion modules. Utilizing wide bandgap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), can help reduce the thermal inefficiencies through use of high-frequency switching topologies, but heat generation is still a primary limiting factor in their implementation. Modules with power densities approaching 100 kW/L and device level heat fluxes in excess of 500 W/cm^2 have recently been demonstrated. However, the increased power density results in much higher temperatures at the device and package level, reducing the reliability of such systems and driving the need for more aggressive cooling solutions.

This topic seeks improvements in thermal packaging technology to enable higher power density, lower cost systems employing WBG devices. In particular, approaches utilizing thermal/electrical co-design, integrated cooling, and cold plates with surface enhancements and novel flow passage geometries, enabled by additive manufacturing, could lead to significant reductions in thermal resistance and pressure drop. Novel cooling approaches and packaging improvements should be compatible with state-of-the-art (SoA) WBG devices. Cold plate technologies, in addition to having good thermal characteristics, must also provide good structural support. Any new packaging material proposals must consider tradeoffs between thickness and thermal resistance, as well as coefficient of thermal expansion (CTE) and durability. Finally, fabrication reliability and cost will ultimately drive commercial adoption.

PHASE I: Develop concepts to reduce the volume of power converter packaging and improve heat transfer performance. Validate thermal design performance through analytical modeling and/or subscale demonstration. Identify technical risks with an emphasis on manufacturing and fabrication processes required to implement the approach. Develop a plan for Phase II demonstration of the concept.

PHASE II: Refine the Phase I design and fabricate a prototype DC-DC modular multilevel converter (MMC) using SoA WBG devices. The prototype should be based on Power Electronic Building Block (PEBB) technology at a power level of at least 100 kW. Experimentally validate the unit’s performance over a variety operating conditions (partial to full power and bi-directional power flow), while maintaining device operating temperature below 175°C, and refine models as needed. Complete a cost analysis of concepts established to ensure the selected technology is competitive with conventional packaging technologies.

PHASE III DUAL USE APPLICATIONS: Complete the final design and manufacturing plans using the knowledge gained during Phases I and II, in order to support transition of system to Navy platforms. Ensure that the final system meets Navy unique requirements, e.g., shock, vibration, and electromagnetic interference (EMI). WBG power modules are seeing increased usage in a wide variety of commercial applications from electric vehicles to renewable energy storage.

REFERENCES:

  1. Naval Power and Energy System Technology Development Roadmap. https://www.navsea.navy.mil/Resources/NPES-Tech-Development-Roadmap/  
  2. U. S. Drive Electrical and Electronics Technical Team Roadmap. https://www.energy.gov/eere/vehicles/downloads/us-drive-electrical-and-electronics-technical-team-roadmap
  3. Iradukunda, A.C., Huitink, D.R. and Luo, F. “A Review of Advanced Thermal Management Solutions and the Implications for Integration in High-Voltage Packages.” IEEE Journal of Emerging and Selected Topics in Power Electronics 8, 2020, pp. 256-271. https://ieeexplore.ieee.org/document/8896946
  4. Broughton, J., Smet, V., Tummala, R.R. and Y. K. Joshi. "Review of Thermal Packaging Technologies for Automotive Power Electronics for Traction Purposes." Journal of Electronic Packaging 140(4),040801, December 2018. https://asmedigitalcollection.asme.org/electronicpackaging/article-abstract/140/4/040801/366154/Review-of-Thermal-Packaging-Technologies-for?redirectedFrom=fulltext
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