Utility Direct Technology Boosts Efficiency Of Fast Charging For Electric Vehicles

Focus:

The Electric Power Research Institute (EPRI) and Enertronics have developed a fast battery charging technology for electric vehicles (EVs). Their “medium-voltage” fast charger technology is based on a solid-state transformer that will allow EV charging to interface directly with a utility’s electric distribution delivery system. (In the utility world, medium voltage refers to a range of about 4 kV to 35 kV.) The Utility Direct Fast Charger technology uses fewer components than comparable dc fast charging systems in use today, is expected to offer lower installation costs, and is significantly more efficient than existing systems. This article explains the concepts behind the EPRI’s Utility Direct Fast Charger technology, its benefits, and shows test results for an initial prototype of a 2.4-kV 45-kVA solid-state, dc fast charging system. The efficiency of this prototype is compared with existing fast charging systems operating from 480 or 208 V input. Plans for future prototypes are discussed. The discussion of charger operation is mostly at a higher level using block diagrams. Circuit-level details of charger design are not discussed.

What you’ll learn:

• How to understand the potential benefits of designing EV charger systems to operate from utility-level voltages in the 4-kV or 15-kV class
• How to understand the benefits of solid-state transformers in utility applications

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Author & Publication:

Arindam Maitra, Electric Power Research Institute, Charlotte, N.C., How2Power Today, Apr 30 2012

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