The electric car market is about to get a major upgrade – researchers from North Carolina State University have developed a new breed of fast chargers for electric vehicles boasting greater power efficiency and a exponentially more minute size. The new technology is called a medium voltage fast charger (MVFC).
The charger is at least 10 times smaller and wastes 60% less power during the charging process compared to existing technology. These improvements do not come at the cost of extended charging time. Still, the research team has said they intend to pursue the project and build a version capable of the same plus faster charging and simultaneous multiple vehicle charging.
Current state-of-the-art technology is 50 kilowatt (kW) chargers that weigh between 1200 and 1600 kilograms. The system involves a distribution transformer, which itself contributes 1000 kilograms of the total weight, and a separate fast charger unit. This massive transformer-charger system necessitates concrete slabs for their proper installation, as the sturdy material is needed to properly support the massive weight. The transformer functions by stepping down to 480V the power acquired from a utility medium-voltage line to which it is attached. The fast charger can then convert the 480V power to DC power that is compatible with electric vehicle batteries.
“Our 50-kW MVFC weighs only around 100 kilograms and can be wall- or pole-mounted,” says Srdjan Lukic, an associate professor of electrical engineering at NC State and one of the researchers who developed the technology. “The MVFC does the work of both the transformer and the fast charger, taking power directly from a medium-voltage utility line and converting it for use in an electric vehicle battery.”
Srdjan Srdic, a research professor from NC State who was part of the team to develop the new charger, said that their technology “offers four times more power from the same system footprint, reducing the system installation costs at the same time”.
The current version of the MVFC charges electric vehicles at the same speed as existing charging stations, as they were designed to operate at 50 kW, which is the same power level used in conventional fast chargers. Despite the comparable charging speed, the MVFC offers a superior charging process thanks to its increased efficiency.
Present models of transformer-and-charger stations report efficiency of up to 93 percent. In contrast, the MVFC prototype reported an efficiency of at least 97.5 percent. This means that at least 7 percent of the power is lost in the conventional charging method, while the MVFC allows for at maximum a loss of 2.5 percent. Operating costs are lowered, revenues increased, and the cost for the customer stays low.
“In other words, we were able to cut the wasted energy by more than 60 percent,” said Srdic.
The development of the current model of the MVFC was done with support from the PowerAmerica Institute, which is a public-private research initiative with offices in NC State and funded by the Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE). Srdic has said that the next steps for the research are to develop multi-port charging technology with a rating capacity of one megawatt that can cater to several vehicles simultaneously. The development of the multi-vehicle MVFC model will be funded by EERE.