Next-Generation Level 2 Charger Is Grid-Smart

November 12, 2014

Kami Buchholz

An all-electric Fiat 500e is being charged with Delta's new smart grid-capable Level 2 charger in one of 24 designated spots at the MGM Grand parking structure in Detroit, MI.

A Level 2 electric vehicle charger that can dispense power based on the available grid supply is undergoing its first field test in Detroit, MI.

Two of the wall-mounted Level 2 smart grid-capable chargers, developed by Delta Products Corp. The units are inside the MGM Grand parking structure in Detroit, Michigan. Compared to Delta's first-generation Level 2 charger, the second-generation system is more than 50% smaller.

Delta Products Corp., Detroit-based DTE Energy, Mercedes-Benz R&D North America, and consulting services company kVA are in the final phase of a three-year smart charging technology development project funded by a $2 million grant from the U.S. Department of Energy.

The Delta-designed and -developed next-generation AC Level 2 charging unit communicates wirelessly with the grid and uses Delta-developed Site Management System software.

This first-of-its-kind charging system means the power supply to electric vehicles (EVs) or plug-in hybrid electric vehicles (PHEVs) can be dialed up or dialed down based on grid demand. The amount of energy going into a plugged-in vehicle is based on information obtained by the charging unit’s Delta-developed Revenue Grade Power Meter.

“If the grid’s power budget is more than the demand, there is no problem. But if the grid does not have the power budget, then the system will dial down the power level temporarily until the grid supply returns to a normal level,” Charles Zhu, PhD, Director of Automotive Business for Delta Products in Livonia, MI, said in an interview with Automotive Engineering.

For a cluster of charging stations, like the project’s Detroit field demonstration, the system can optimize each vehicle’s charging needs based on the utility company’s energy profiles.

On the utility side, smart management of the grid’s power can help electrical transformers reach their expected life spans, according to Haukur (Hawk) Asgeirsson, DTE Energy’s Manager of Engineering. More than two million customers in Southeast Michigan receive electricity via DTE.

“The oil in the transformer and its core—that consists of copper, aluminum, and iron components—will heat up during the summertime when the grid is at maximum capacity. Heat shortens the life span of our transformers, so we were initially concerned about electric vehicles being charged at night because the transformers would not have time to cool down,” Asgeirsson told Automotive Engineering.

DTE worked with engineering students from the University of Michigan-Ann Arbor to determine the potential impacts if transformers were not allowed to cool down because of night-time vehicle charging.

“Our findings, based on modeling and studies, indicate that even if 60% of our customers plugged in vehicles to charge at night, that would not appreciably shorten the life of our transformer assets,” said Asgeirsson. “We may eventually have that many customers charging vehicles, but getting to that saturation point is going to take some time.”

In the U.S., EVs and PHEVs each had a 0.3% market share in 2013, according to IHS Automotive data. “Through 2020, the top markets for EV production will be the U.S. and Europe, while Europe, China, and North America are expected to lead in PHEV production during that same time frame,” said Devin Lindsay, IHS Automotive’s Principal Analyst, North American Powertrain Forecast.

The first deployment of Delta’s next-generation charging stations is in the sixth floor of Detroit’s MGM Grand parking structure, which is adjacent to DTE Energy headquarters. Said M.S. Huang, President of Delta Products Corp.: “This site is serving as a test case for 24 of [Delta’s] second-generation charging units. Over the next few months we’ll be able to obtain user feedback from Michigan’s largest deployment of smart grid-capable charging stations.”

A smart grid-charging system means utility companies can manage load during peak hours, and customers can take advantage of off-peak electricity rates. Said Asgeirsson: “With smart charging, we can accommodate more vehicles on the grid.”

Delta says its commercially available smart grid-capable Level 2 charger is the first such charging device with a sub-$450 suggested price in North America.