CURENT ERC Develops New Device for Faster, Cheaper Power
All electronics¾from laptops to electric motors¾rely on power switching devices to control or convert electrical energy from high to low voltage to operate properly. A new patent-pending, super-fast electrical device to measure electric current for power-switching has been developed for a master’s thesis at the University of Tennessee-Knoxville (UTK) and is being licensed by Keysight Industries, a firm dedicated to accelerating innovations in electronic design and optimization. The new technology was developed as part of a research program to help significantly lower the cost and improve the energy efficiency of the power-switching that is conducted by the Center for Ultra-Wide-Area Resilient Electric Energy Transmission Networks (CURENT), an NSF Engineering Research Center (ERC) supported by NSF and the U.S. Department of Energy and headquartered at UTK, with partner organizations including Northeastern University, Rensselaer Polytechnic Institute, and Tuskegee University.
A power semiconductor is a device used as a switch in power electronics. However, most of today's high-voltage power electronics systems are based on silicon semiconductor devices, which have notable performance limitations. Wide-bandgap (WBG) semiconductors are next-generation power switching devices that improve performance and efficiency of high-power systems in a wide range of applications, including new lighting technologies, computer power supplies, industrial motor drives, and automobiles. High bandwidth sensors are required to measure the WBG devices' performance during sudden, unscheduled changes in inputs because of their very fast switching speed. The sensor must also introduce little disturbance to the switching power loop. However, despite the benefits, new technology to facilitate WBG adoption must be well-priced to compete in the marketplace. CURENT’s patent-pending technology is both capable of sensing the very fast transient current needed for the new WBG semiconductors (and provides better measurements) and is affordable because it uses low-cost components. Keysight Industries worked with the researchers on its development and will be able to take it the next step toward commercial use.
High-bandwidth sensors are required to measure WBG devices transient behavior because of their very fast switching speed. In addition to the high bandwidth, the current sensor must also avoid excessive extra parasitic inductance, which drastically changes the switching behavior, making the measurement result invalid. For this project, conventional high bandwidth current sensors were first reviewed here to understand their limitations.
Shunt resisters are a common and simple approach to current sensing. Coaxial shunts have been widely used for fast currents, but highly integrated electronic devices prefer low-cost surface mounted devices because of their small sizes and relatively low prices. CURENT combined the structure of coaxial shunt resistor and alumina substrate of surface mount thin film resistors to create its novel current sensor surface mount coaxial shunt resistor (SMDCSR). Experimental testing verified the device’s capability of achieving very high bandwidth of up to 2 GHz while introducing little disturbance. Compared with state-of-the-art commercial products, SMDCSR achieves more than 10x higher bandwidth and less than 1/10 insertion inductance. SMDCSRs are thus ideal for current measurement where high bandwidth and low electrical footprint are required, especially the WBG device’s dynamic characterization.
