Towards Wide Range Efficiency Improvement on Onboard Chargers for Plug-In Electric Vehicles

Event Date: December 2, 2013
Speaker: Professor Alireza Khaligh
Speaker Affiliation: Electrical & Computer Engineering Department, Institute for Systems Research, University of Maryland at College Park
Time: 10:00 AM
Location: EE 118

The impending global energy crisis has opened up new opportunities for the automotive industry to meet the ever-increasing demand for cleaner and fuel-efficient vehicles. These challenges have compelled the development of drive-trains either fully or partially electrified in the form of electric (EVs) and plug-in hybrid electric vehicles (PHEVs), which are collectively addressed as plug-in electric vehicles (PEVs). The power electronics is emerged as an enabling technology in deployment of next generation of electrified transportation systems. There are many power electronic converters in a PEV, including an onboard charger, propulsion machine inverter, energy storage bidirectional converter, and 14V auxiliary loads dc/dc converter. The demand for higher efficiency, higher power density, specific power and better thermal management poses additional challenges for these power electronic converters to accommodate. This presentation will put forward some of the current research areas, which are being pursued in the Power Electronics, Energy Harvesting and Renewable Energies Laboratory (PEHREL) with the emphasis on integrated power electronic converters for PEVs at the University of Maryland. In particular, this presentation will focus on developing highly efficient isolated onboard chargers for PEVs.

The onboard battery charger of a PEV typically consists of two power stages; front-end stage for rectification of ac input voltage and power factor correction, and second-stage dc/dc converter for voltage regulation and galvanic isolation. In this presentation a new technique to track the maximum efficiency point of a LLC converter over a wide range of the battery State-of-Charge (SoC) will be introduced. With the proposed approach, dc link voltage follows the battery pack voltage. The operating point of the LLC converter is always constrained to the proximity of the primary resonant frequency, so that the circulating current in the magnetizing inductor, and the turning off currents of MOSFETs are minimized. In comparison to conventional approaches, efficiency improvement of 2.1% at the full load condition and 9.1% at the lightest load condition is demonstrated


Alireza Khaligh is an Assistant Professor and The Director of Power Electronics, Energy Harvesting and Renewable Energies Laboratory (PEHREL) at the Electrical and Computer Engineering Department (ECE) and the Institute for Systems Research (ISR) in the University of Maryland at College Park (UMCP). Prior to UMCP, he was an Assistant Professor at Illinois Institute of Technology (IIT), and also a Post-Doctoral Research Associate in the Grainger Center for Electric Machinery and Electromechanics in the University of Illinois at Urbana-Champaign (UIUC).

Dr. Khaligh’s major research interests include modeling, analysis, design, and control of power electronic converters for electric and plug-in hybrid electric vehicles, energy harvesting, microrobotics, and renewable energy systems. He is an author/coauthor of over 110 journal and conference papers. Dr. Khaligh is the recipient of various awards and recognitions including the 2013 George Corcoran Memorial Award from ECE Department of UMCP, 2013 and 2012 Best Vehicular Electronics Awards from IEEE Vehicular Electronics Society, 2010 Ralph R. Teetor Educational Award from Society of Automotive Engineers, and the 2009 Armour College of Engineering Excellence in Teaching Award from IIT. Dr. Khaligh was the General Chair of the 2013 IEEE Transportation Electrification Conference and Expo (ITEC), Program Chair of the 2011 IEEE Vehicle Power and Propulsion Conference (VPPC), as well as the Grants and Awards Chair for the 2012-2013 IEEE Applied Power Electronics Conference and Expo (APEC). He is the Assistant Program Chair of the 2014 APEC. Dr. Khaligh has been an editor, an associate editor and a guest editor for a few of IEEE Transactions including IEEE Transactions on Vehicular Technology, IEEE Journal of Emerging and Selected Topics in Power Electronics, and IEEE Transactions on Power Electronics.