Power Electronics: Small, reliable, and energy efficient
Power electronics convert and control electrical power across the grid and in a growing array of products used by industry, consumers, the military, and utilities. Wide bandgap (WBG) semiconductors—the same materials used in LED light fixtures and many flat screen TVs—can improve energy efficiency in the next generation of power electronics while also reducing cost and system size. WBG semiconductors used in variable frequency drives (VFDs), for example, increase the efficiency of industrial motor systems and expand the range of motor applications in which these energy-efficient drives are cost-effective. Moreover, WBG-based power electronics are more compact and reliable—even as they function at higher power loads, operating temperatures, and frequencies than today's widely used, silicon-based power electronics.
WBG: Enhanced capabilities
Semiconductors are materials that can allow electricity to flow more readily than insulators—but less readily than conductors. This property makes semiconductors extremely useful for fabricating power electronic chips that control and convert electrical power (i.e., adjust the voltage, current, and frequency as required by various types of equipment and applications).
A bandgap is the term used for the amount of energy needed to release electrons in semiconductor materials so that the electrons can move freely, enabling the flow of electricity. WBG semiconductors have bandgaps significantly greater than those of silicon semiconductors. Electrical current applied to WBG semiconductors will excite fewer electrons across the gap, enabling superior current control and reducing energy losses.
WBG semiconductors are able to operate at higher voltages and power densities than silicon-based semiconductors, allowing the same amount of power to be delivered with fewer chips and smaller components. In addition, these more powerful WBG semiconductors can operate at higher frequencies, which helps to simplify system circuitry and reduce system costs. Furthermore, WBG semiconductors tolerate heat better than silicon. As a result, WBG-based power electronic chips can operate in harsher conditions without degrading the semiconductor material. This greater thermal tolerance (300°C vs. 150°C) reduces the need for bulky insulation and additional cooling equipment, allowing for more compact system designs. Collectively, these performance properties of WBG semiconductors will enable technology developers to continue designing increasingly more compact, efficient, reliable, and affordable power electronics in the decades ahead.
Building more cost-efficient power electronic systems
Semiconductor chips are fabricated by creating complex circuits on a thin, circular wafer (substrate) using a series of iterative processing steps (e.g., oxidizing, etching, doping, etc.). These fabrication processes are automated to produce multiple, integrated circuits or chips on a single wafer. The wafers are then sliced apart to create a number of identical chips. As WBG wafers become available in larger sizes compatible with the automated equipment and infrastructure used by the silicon industry, WBG chip production will scale up substantially.
As shown in the above graphic, chips perform critical power conditioning functions in devices like rectifiers (convert AC electricity to DC), inverters (convert DC electricity to AC), and variable frequency drives (which include both inverters and rectifiers). WBG semiconductor-based devices perform these functions more efficiently, yielding significant energy savings:
- Industrial Motor Systems: Motor systems use nearly 70% of the electricity consumed in U.S. manufacturing today. Many manufacturers size their motors to handle peak demand, so these motors often use more power than is actually needed. Some motor systems use a variable-frequency drive (VFD) to dynamically adjust motor speed to match power requirements and save energy. VFDs that take advantage of WBG power chips can directly save the energy equivalent of the electricity used by 1 million homes annually. More efficient and compact WBG-based VFDs are also likely to expand the range of motors in which VFDs are cost-effective.
- Consumer Electronics and Data Centers: Power converters for data centers and consumer electronics (such as laptops, smart phones, and tablets) account for nearly 4% of U.S. electricity use today, and the demand for these facilities and products continues to rise. The small converter on the cord of your laptop computer, for example, converts the AC power from your wall outlet into the DC power used by your laptop. Similarly, data centers need to convert power to meet the needs of the diverse components of modern data center systems. WBG chips will eliminate up to 90% of the energy losses in today's rectifiers that perform these conversions. WBG-based power electronics in consumer electronics and data centers can save enough electricity annually to power over 1.3 million homes.
- Conversion of Renewable Power: Renewable energy generated by wind turbines and solar photovoltaic systems must be converted from DC to AC prior to upload to the electric grid. The WBG chip provides the required conversion in the inverter. More efficient WBG-based power electronics for solar and wind energy conversion can annually save enough electricity to power more than 700,000 homes.
The Next Generation Power Electronics National Manufacturing Innovation Institute will use $70 million provided by the U.S. Department of Energy's Advanced Manufacturing Office to support and manage its programs over the next five years. This Institute is one of three new innovation hubs announced by President Obama in his 2013 State of the Union address and part of the National Network for Manufacturing Innovation (NNMI). The Institute will establish a collaborative community devoted to wide bandgap power electronics. It will create, showcase, and deploy new power electronic capabilities, products, and processes that can impact commercial production, build workforce skills, enhance manufacturing capabilities, and foster long-term economic growth in the region and across the nation.