Charging electric vehicles cheaper and faster

Charging electric vehicles cheaper and faster
Saeid Haghbin and his co-workers have developed unique solutions for isolated and non-isolated integrated electrical vehicle chargers. Credit: Peter Widing

Researchers at Chalmers have developed a unique integrated motor drive and battery charger for electric vehicles. Compared to today's electric vehicle chargers, they have managed to shorten the charging time from eight to two hours, and to reduce the cost by around $2,000.

Saeid Haghbin, doctor of electric power engineering, undertook his doctoral studies in order to develop the optimal electric vehicle charger. The result is a novel high-power integrated motor drive and for vehicle applications, where a new power transfer method has been introduced involving what is known as a rotating transformer.

"The ideal scenario would be to have a charger powerful enough to charge a car in five to ten minutes, but this would cost over $100,000, which is more expensive than the car itself," says Saeid Haghbin. "The question we posed was: how can we reduce the size, weight and price of the on-board charger".

Since the electric motor and the inverter are not used during battery charging, the researchers looked into the possibility of using them in the charger circuit and building some kind of integrated motor and battery charger. In other words, would it be possible to use the motor and inverter in the charger circuit to increase the charging power at a lower cost?

Charging electric vehicles cheaper and faster
Model of the integrated motor drive and battery charger. The image shows a plug-in hybrid electric vehicle, which also has a fuel tank and a combustion engine, but the technology system works equally well with a purely electric vehicle.

"Instead of having a separate isolated battery charger, we introduced a new concept for the power transfer, the rotating transformer, which was developed to transfer electric while rotating," says Saeid Haghbin. "The battery is charged through the transformer and a split-phase electric motor that was especially designed for this purpose."

The Chalmers integrated charger is, from a university perspective, still on laboratory level. To achieve a more optimal system, further investigations and experimentation are necessary. However, the product has resulted in both a Swedish and an international patent. Chalmers is trying to find a potential industrial user, and AB is working on the concept for further enhancement to be used in its system.

"Electric cars have been discussed as a possible solution to reduce carbon emissions for a long time, but scientists debate whether this mode of transportation is the future or not," says Saeid Haghbin. "If we manage to solve the main problems with the battery and the battery chargers, I think the will succeed. And in general, I think electric transportation will become more common in the future, for example trains, trams and plug-in hybrids."

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More information: Read the PhD thesis "Integrated Motor Drives and Battery Chargers for Electric or Plug-in Hybrid Electric Vehicles."
Citation: Charging electric vehicles cheaper and faster (2013, April 30) retrieved 19 August 2019 from
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User comments

Apr 30, 2013
I dont get this but it is undoubtable that the charger and charging system and NOT the battery is the weakest link in th EV adoption scheme. A leap must be made in this area before EVs are ready for primetime. Tesla eat your heart out.

Apr 30, 2013
Quick charging is one of the major snags keeping EV from being widely adopted. People want more range and they want to take weekend trips. Some sort of on-board charger would be a boon.

May 01, 2013
"The ideal scenario would be to have a charger powerful enough to charge a car in five to ten minutes, but this would cost over $100,000, which is more expensive than the car itself," says Saeid Haghbin.

I highly doubt that. $100,000 would not be out of line for a recharging station modeled on a gas station. I doubt the individual pumps combined with their share of the tank system could be had for much less than that, and recharging in 5 to 10 minutes at a station would be a game changer for electric vehicles. I'm pretty sure it's the current state of lithium-ion battery technology that prevents such fast charge times.

May 01, 2013
At ten minutes, the rate of energy transfer is high. Any inefficiency would produce significant heat.

May 13, 2013
Biggest obstacle for electric cars is currently the battery performance in terms of price versus capacity. Affordable batteries do not have enough capacity and ones having enough capacity are too expensive. Until there will be better batteries or cheap enough onboard energy charger (LENR, magnetic motor etc), electric cars will not become mainstream.

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