Staying Cool with Power Electronics and Electrical Machinery System Designs | News

Recent advances underpin new research in transportation and manufacturing


NREL researcher Sreekant Narumanchi uses a liquid cooling loop to characterize the reliability of the dielectric fluid jet impact cooling approach developed by NREL. Photo by Dennis Schroeder, NREL

Always looking to the future, researchers at the National Renewable Energy Laboratory (NREL) are revolutionizing clean energy mobility beyond light electric vehicles (EVs) by building advanced power electronic systems that control the flow of electricity to power large advanced electrical machinery, including those used in airplanes, trains and heavy transport. With support from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) programs, NREL is partnering with new research projects in the areas of sustainable aviation, networked storage, and energy. energy efficient computing.

“It’s an exciting time to work in power electronics,” said Sreekant Narumanchi, senior researcher at NREL. “These important partnerships allow us to develop the most advanced system designs to reduce costs, reduce component footprint, and improve overall performance, reliability and efficiency.”

Electrified mobility applications use power electronics, such as inverters, converters, and chargers, to manage the flow of electricity between the battery, electric motor, and other powertrain components. Depending on the application, systems must operate at higher temperatures, voltages, switching frequencies, and power conversion efficiencies. Advanced systems bring advanced challenges, but NREL researchers are pioneering power electronics and electric motor enclosures, solid-state electrothermal designs, and thermal management systems for transportation and manufacturing. NREL’s experimental facilities offer world-class evaluation and measurement in heat transfer, reliability characterization, package prototyping, and thermal and thermomechanical modeling.

State-of-the-art power electronics and electrical machinery for optimum performance

A woman using laboratory equipment.

NREL researcher Emily Cousineau uses the Instron 5966 Double Column Tabletop Test System to identify microscopic defects in material layers for failure analysis.
Photo by Dennis Schroeder, NREL

Power electronics are at the heart of power conversion in an electrically powered vehicle, managing the flow of power between the various vehicle components. Next-generation power electronics and electric machinery designs can improve the performance of electric vehicle powertrain components and digital technologies that make electric vehicles safer and smarter. In larger applications, such as heavy equipment, power electronics also require high power and high temperature optimization.

As a leader in wide bandgap (WBG) power electronics research, NREL evaluates and develops electrothermal semiconductor designs and packaging technologies that provide improved reliability, power density, and efficiency. . WBG devices, such as silicon carbide or gallium nitride, offer lighter, more compact and potentially robust alternatives to traditional components. Continued research helps highlight these benefits and increase adoption of WBG systems.

“Our team works with industry partners, such as General Electric, Cummins, BorgWarner and John Deere, to optimize the thermal performance of inverters and high-power-density WBG electric motors,” Narumanchi said. “The lighter overall weight, footprint and improved performance of these designs offer clear advantages in energy efficiency and operating costs for electrified mobility applications.”

NREL researchers leverage state-of-the-art modeling and characterization to perform reliability assessment and failure analysis of new power electronics designs. Advanced modeling capabilities allow researchers to identify thermal bottlenecks and optimize the performance of power electronics packages. Additionally, researchers are leveraging in-depth characterization through thermal, humidity, and vibration testing to better understand how stressors affect emerging technologies. As a result, systems designed by NREL prioritize safety, reliability and efficiency for optimum operating performance.

Unparalleled thermal management and cooling capabilities

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NREL researcher Gilbert Moreno prepares dielectric fluid loop experiments to assess the heat transfer of electrical system components. Photo by Dennis Schroeder, NREL

Overheating can cause irreparable damage to power electronics and electric motors, resulting in system slowdown or malfunction. Advanced thermal management systems are critical to the performance and safety of all electrified traction drive components, including solid-state power devices, power modules, inverters, and electric motors. NREL engineers are experts in system-level thermal management designs that incorporate advanced heat transfer to regulate temperatures throughout the power electronics and electric machine system. Additionally, recent innovative cooling strategies, such as jet impingement, are pushing the boundaries of power electronics and electrical machinery design.

“Advanced cooling and thermal management systems optimize the performance of electric vehicles and advanced machinery,” Narumanchi said. “These systems help keep temperatures within operational limits, reduce component bulk and weight, improve component efficiency, and increase vehicle efficiency and range. Ultimately, these benefits help reduce fuel consumption and greenhouse gas emissions.

An ongoing ARPA-E collaboration with Stanford University is “Explore the limits of cooling for extreme heat flow applicationswith improved chip thermal management for data centers and power electronics. Stanford University researchers are developing a new cooling technology, the Extreme Heat Microflux (EHFμ-) cooler, supported by experimental evaluation of the reliability of thermal management technologies at NREL. The EHFμ-Cooler significantly reduces the temperature of the device, resulting in a heat flux dissipation of more than 1000 W/cm2 to cool the device.

NREL’s thermal management research also includes two projects within the Aircraft-Class ARPA-E Synergically Cooled Electric Motor Program with Integrated Drivers (ASCEND) to support the development of innovative, lightweight and ultra-efficient electric motors, motor drives and thermal management systems for sustainable aviation. The first project, led by the General Electric Global Research Center, will design a 2 MW fully integrated all-electric aircraft powertrain and demonstrate a 350 kW lab-scale prototype to enable commercial aircraft to zero-carbon narrow body with all-electric propulsion. The second project, led by Marquette University, focuses specifically on building a high-power-density engine for aerospace propulsion. NREL’s support for these projects includes thermal management modeling, analysis and characterization of advanced cooling designs and inverter components, as well as thermomechanical design and techno-economic analysis for various inverter components. power, electric motor and integrated electric drive electronics.

Power electronics expertise for a clean energy future

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Joshua Major, a researcher at NREL, operates the Accelerated Drive Cycle platform comprising a single-axis electrodynamic agitator and an AGREE-style environmental chamber used to perform reliability testing on system components. Photo by Dennis Schroeder, NREL

These existing partnerships barely scratch the surface of NREL’s advanced capabilities in power electronics and electrical machinery, and more exciting research is just beginning. ARPA-E recently selected three new projects supported by NREL expertise:

  • Repurposing infrastructure for gravity storage using underground potential energyled by NREL, will use system-level electromechanical modeling to determine transmission component sizing to convert idle oil and gas wells into energy storage devices.
  • Bringing three-dimensional packaging and thermal management to power electronics, led by Synteriswill include NREL research to improve thermal management, power density, performance and lifetime of ceramic packages for power electronics modules.
  • Cable Substation for Adaptable and Low-Cost Electrical Distribution (SCALED)led by Virginia Polytechnic Institute and State University, will include NREL thermal management research to develop compact, high-performance power electronics in the context of networking applications.

Under the ARPA-E OPEN 2021 program, these projects prioritize high-impact, high-risk technologies that support new approaches to addressing clean energy challenges.

“Each of these projects involves exciting new collaborations with industrial and academic partners, as well as collaborations between groups at NREL, to develop innovative power modules, packages, converters and transmission components that impact many multiple energy efficiency and renewable energy applications,” Narumanchi said.

Learn more about sustainable transport and mobility and advanced manufacturing research from NREL.

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