Room BA1130
Bahen Centre for Information Technology
University of Toronto
40 St. George Street
Toronto, M5S 2E4   map
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Solar energy has long been recognized as one of the most abundant forms of energy, while economic and political considerations have limited its role in North America’s energy mix. Countless research efforts around the globe are contributing to the steady decline in the cost of solar power, with the promise of reaching grid parity in the near future. This is a complex target, as the price of conventional energy sources are constantly in flux and heavily dependent on government subsidies. The penetration level of solar power is increasing in North America due to government incentives and multi- disciplinary technological advances, however Canada remains well behind other industrialized nations in the adoption of sustainable technologies. This talk will review the basics and state-of-the-art in photovoltaic (PV) energy conversion, while the main focus is on the power electronics used to maximize the harvested energy. Small PV arrays in the 2-10 kW range are increasingly being deployed on residential rooftops in urban environments. These applications present a unique set of economic and technological challenges that will be explored in this presentation. Performing maximum peak power tracking (MPPT) on a PV array is commonly used to continuously optimize the total harvested power under time-varying temperature and illumination fluctuations. It has recently been demonstrated that performing MPPT on a per-panel basis, instead of using a single MPPT controller across the entire PV array can substantially improve the total system efficiency. The increased efficiency is due to the fact that in conditions where each panel experiences unique illumination conditions, the total power can only be maximized if each panel is operated at its individual peak power point using distributed MPPT controllers (DMPPT). The variation in illumination across the PV panels results from shading due to nearby structures, trees, clouds as well as accumulated dirt. There are currently two competing DMPPT schemes, namely (1) micro dc-dc converters for series-connected panels with a centralized DC-AC inverter and (2) micro-inverters for parallel connected-panels. Several companies have already commercialized a number of DMPPT solutions. Quantifying the benefits of DMPPT remains a challenge but early results are very promising. The talk will highlight the implications that the two competing DMPPT schemes have on system cost, efficiency and reliability.

Olivier Trescases is an Assistant Professor in the Department of Electrical and Computer Engineering at the University of Toronto, where he completed his Ph.D. degree in 2007. His doctoral thesis, entitled "Integrated Power Supplies for Portable Applications" deals with efficiency optimization techniques and mixed-signal control schemes for embedded low-voltage dc-dc converters. Dr. Trescases’ past research topics include high-efficiency switch-mode power supplies, quasi-resonant dc-dc converters, dynamic voltage/frequency scaling in deep sub-micron VLSI circuits, all-digital class-D audio amplifiers and motor drives for hybrid electric vehicles. From August 2007 to December 2008, Dr.Trescases worked as a concept engineer at the high-integration group at Infineon Technologies AG, where he developed integrated power management circuits for automotive applications. He has authored several papers in the area of integrated dc-dc converters, for which he has received two IEEE best-paper awards in 2003 and 2006. Dr. Trescases’ current research group focuses on high-efficiency power converters for industrial, automotive, aerospace and renewable energy applications.