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Power Devices and Thermal Metrology


The Power Devices and Thermal Metrology Project develops electrical and thermal measurement methods and equipment to support development and application of advanced power semiconductor devices and ICs. The Project performs research enabling integration of advanced power electronics technologies into future energy systems, and supports development of Smart Grid measurement methods and standards for Distributed Generators, Renewables, Storage and Microgrids. 


Switch-mode power conversion using power semiconductor devices provides the means to convert electricity from one voltage to another, to convert between direct current (DC) and alternating current (AC), to condition power waveforms to meet device and system needs, and to control motion by modulating electric power to motor windings or mechanical actuators. As power semiconductor technology has evolved over the last few decades, from slow low-voltage low-power devices to today's fast high-voltage high-power devices, switch mode power conversion has become pervasive and essential in electrical and electronic systems.

NIST provided the theoretical foundation and measurement methods that aided development and rapid adoption of the most widely used high power semiconductor device known as the Insulated Gate Bipolar Transistor (IGBT). As the IGBT began to reach its fundamental limits at high voltage, NIST work transitioned to devices made with new wide-band-gap semiconductor materials such as silicon-carbide (SiC) that are beginning to replace conventional power devices made with silicon. Power semiconductor devices made with SiC enable operation at higher voltages, higher speeds, and higher temperatures. NIST work focuses on measurements, modeling and analysis that enables industry to more rapidly integrate advanced power semiconductor device, package, and cooling system technologies into a wide range of applications. NIST also plays an advisory role in defining new programs for development of advanced power devices in support of DOE and DOD initiatives.

Advanced power electronics technologies are becoming critically important to meet the nation's energy and defense priorities such as energy independence, increased capacity and stability/resiliency of the power grid, renewable/clean power generation, electric transportation, and electrification of DOD platforms and systems. For example, power conditioning systems (PCSs) are required to convert low voltage unregulated power produced by renewable/clean energy sources, such as photovoltaic solar or wind, to high voltage power synchronized with the grid. PCSs are also required to charge plug-in electric vehicle batteries, and to deliver power waveforms to the windings of the electric motors including vehicle propulsion motors. NIST is leading efforts to coordinate industry and other federal agency programs to reduce cost and improve performance of these PCSs. NIST is also developing electro-thermal-network component models and measurement methods to support rapid adoption of advanced electric vehicle propulsion system technologies and advanced high-voltage, high-frequency switch mode power conversion.

As electrification of energy systems has become pervasive, information network technology has become a key enabler for advancement of mobile and stationary power systems. The Energy Independence and Security Act of 2007 assigned NIST "the primary responsibility to coordinate development of a framework that includes protocols and model standards for information management to achieve interoperability of smart grid devices and systems…" To meet this responsibility NIST established the Smart Grid Interoperability Panel (SGIP) as a forum to coordinate the many stakeholders and standards development organizations (SDOs) involved in Smart Grid. Recently, NIST is also defining new laboratory programs to metrology needs for smart grid.
The Power Device and Thermal Metrology Project initiated and leads the SGIP Distributed Renewables, Generators, and Storage Domain Expert Working Group as well as three SGIP priority action plans (PAPs): PAP 7 on distributed generator/storage standards for interconnection requirements, information models, and test; PAP 16 on wind plant communication standards; and PAP 21 on information models standards for measured and forecasted weather data supporting renewable generators and grid operations. In addition, the Power Device and Thermal Metrology Project also leads a new Priority Action Plan — PAP-24 on Microgrid Operational Interfaces, which was recently approved in July by the SGIP 2.0 Board of Directors. Recently, the concept of the microgrid has evolved to fully recognize the benefits of microgrids in terms of market participation, renewable integration, cost savings and reliability and resiliency to the grid.

The smart grid efforts of this project have played an important role in coordinating distributed generator operators, utilities, standards development organizations, and federal and state regulatory commissions in advancing distributed generator functionalities such as voltage regulation and voltage/frequency ride through that will provide better grid stability and resiliency while also increasing the value propositions of renewable generators. This Project is also playing a major role in developing the new NIST Smart Grid Interoperability Test Bed activities focused on interoperability of interconnection equipment and controllers for microgrids and distributed generation/storage PCSs. The new laboratory will evaluate performance of both grid-facing and customer-facing functionalities of microgrids and distributed generation/storage devices such as customer ability to isolate from disturbances and to operate independently during grid outages, and the ability to participate in grid energy and ancillary services markets and to interact with grid operations to provide stability/resiliancy.

Major Accomplishments:

  • NIST provided initial information gathering for the new Manufacturing Innovation Institute on WBG Power Electronics announced by President Obama in January 2014 by planning and convening at NIST the "NIST/DOE High Megawatt Power Conditioning System Workshop" in May 2012 at the request of the DOE Advanced Manufacturing Office. 
  • NIST recently held two workshops on High-Megawatt (HMW) Variable Speed Drive (VSD) Motors and Front End Power Electronics at the request of DOE EERE. These workshops are initiatory information gathering for the DOE EERE government working group on Next Generation Electric Machines that is defining new programs in this area.
  • NIST in cooperation with the Office of Assistant Secretary of DOE EERE, initiated and organized the "GaN Power Device Standards Roundtable" held in March 2014
  • NIST developed and experimentally validated physics-based electro-thermal Saber models for high-voltage (i.e. blocking voltages from 12 kV to 20 kV) SiC buffer layer n-channel IGBTs. These devices are being developed by several DOE and DOD programs including DOD Manufacturing Technology programs and DOE ARPA-e device development programs. NIST power device models and simulations are used for device design trade-offs and for module-package and circuit integration.  
  • NIST developed and experimentally validated models for first-of-a-kind 4.5 kV Si IGBT/SiC JBS hybrid power modules, and transferred the models to the Naval Research Lab and NAVSEA Electric Ship Office to be used for evaluating design considerations of Naval electric ship power converters using these experimental modules.
  • NIST unique high-voltage, high-frequency power switching tester demonstrated fast switching capability of the first 12 kV SiC n-IGBTs and 15 kV SiC p-IGBTs. The world-class NIST high-voltage, high-frequency power semiconductor test capability is used extensively by industry and other agency programs to evaluate performance of first-of-a-kind high-voltage power devices.
  • NIST led the Interagency Advanced Power Group (IAPG), Electrical Systems Working Group (ESWG) that coordinates Army, Navy, Air Force, NASA, DOE and NIST programs on microgrids and wide bandgap power devices.
  • The NIST developed and experimentally validated electro-thermal-mechanical models for electric vehicle propulsion inverter modules were used to demonstrate safe operation and reliability of an advanced double-sided-cooling IGBT package, and to integrate a new soft-switching inverter module with electric vehicle propulsion inverter and cooling systems. 
  • NIST drafted and championed a new SGIP Priority Action Plan (PAP 24) proposal that was approved by the SGIP Board of Directors. NIST convenes biweekly meetings of PAP 24 and identified leaders for each of the tasks: microgrid standards scoping document, microgrid use cases, microgrid interconnection standards, microgrid controller, microgrid regulatory, microgrid information models, and microgrid test. The PAP has already developed a set of microgrid use cases that are posted on the EPRI use case repository and has created a new standards project: IEEE P2030.7 Standard for the Specification of Microgrid Controllers that has its first meeting in October 2014.
  • Hefner designed, constructed and equipped a new laboratory to assess critical metrology challenges in interoperability testing of Smart Grid distributed generator/storage and microgrid, interconnection equipment and controllers. This interoperability testing and PAP 24 activities are coordinated with the new DOE OE Microgrid Research program that just announced eight new microgrid awards.
  • NIST leadership in initiating PAP 7 has resulted in several new distributed generator/storage interconnection standards, a new smart inverter information model standard, and several new regulatory proceedings requiring the use of functions defined in these standards.

Lead Organizational Unit:



Allen R. Hefner, Jr., Project Leader
Colleen Hood

Hefner developing world-class High Voltage, High Frequency Power Transistor Switching Tester. (Copyright Robert Rathe)

Hefner developing world-class High Voltage, High Frequency Power Transistor Switching Tester. (Copyright Robert Rathe)


Allen R. Hefner, Jr.
301-975-2071 Telephone

100 Bureau Drive, M/S 8120
Gaithersburg, MD 20899-8120