This proposal seeks funding for the Center for Grid Connected Advanced Power Electronics Systems (GRAPES) studies conducted by the University of Arkansas site (lead) and the University of South Carolina site. Funding Requests for Fundamental Research are authorized by an NSF approved solicitation, NSF 10-507. The solicitation invites I/UCRCs to submit proposals for support of industry-defined fundamental research.
The technical merit of this project is in advancing the state of the art in fully-integrated, fullywide-bandgap, fully-isolated power electronic converters based on GaN. This will produce new state-of-the-art boundaries in switching speeds, volumetric reduction, power density, temperature of operation, efficiency, and immunity to interference. Eventually, these technologies will be applied to grid-connected systems. The outcome from this fundamental effort has the potential for transforming how power electronic systems are designed for numerous smart-grid and power converter applications. The team of participating university faculty is very well qualified to conduct the project and they are supported by capable and knowledgeable professionals from their industry members. It is a creative proposal that is well conceived in that it takes a practical, proof-of-concept approach to the problem. Both universities are well equipped with excellent facilities to perform their respective research tasks.
The proposed project has the potential to make a huge societal impact if their approach is proven successful for the development of more integrated, less expensive and more efficient power electronics for converter and power grid applications. The research plan engages graduate students in the research effort and will have an influence on undergraduate students as well. Many of the participating students are expected to come from underrepresented minority groups. The research results will be distributed broadly and communicated directly to key industry representatives.
The electric grid is undergoing revolutionary changes with the incorporation of renewable and distributed energy sources and the use of modern technologies that increase controllability, reliability and power transfer capabilities. The enabling technology for all of these changes is power electronics. Power electronic converters use controllable power semiconductor switches to perform power conversion from a given input form to a desired output form. Power electronic converters act as interfaces between renewable energy sources and the grid and provide advanced power flow control capabilities. One of the challenges in the realization of power electronic converters for the power grid is the electrical isolation requirements for the control of the power semiconductor devices, given the high voltages involved. There is a need for power switches that can operate at high voltage, at high temperature and at high switching frequencies with low losses. Power switches fabricated from a wide bandgap materials such as SiC or GaN, can outperform conventional silicon switches, due to material property advantages. One common problem in grid-connected applications is the need for high- voltage-isolation of the gate drivers that control the power semiconductor switches, while yet operating efficiently at the high switching frequencies and high temperatures made possible by wide bandgap devices. The gate driver must also provide the appropriate protection and sensing functions needed for reliable power converter operation.The project investigates an approach to provide isolated control of power electronic converters by realizing optically coupled gate drives for the wide bandgap power devices used. The goal of this project is to develop a high-performance optical control for SiC and GaN devices. The proposed approach for the gate driver includes optical supply of gate control energy, optical switching of gate potentials, and optical feedback of sensed quantities such as main switch current. The intellectual merit is in the identification of a novel method to provide the required isolation by using light to transfer both the control signal and the power required over the isolation barrier. The broader impact of the project is in the possibility to contribute to the revolutionary improvements that are occurring in the power grid. The result of the investigation was that the proposed approach cannot be realized at the present time due to limitations of current technology for wide bandgap optical devices. Once better devices become available, the proposed approach has the potential of significantly contributing to power grid evolution.
