A new, greatly improved electric vehicle charger design has been developed by researchers at the Chalmers University of Technology in Sweden. The unique integrated motor drive and battery charger greatly shorten the charging time, from about 8 hours to 2, and reduce the cost by around $2000, as compared to currently used designs.
The new research was undertaken with the aim of developing the “optimal” electric vehicle charger — which hasn’t yet been achieved, but significant improvements have clearly been made. These improvements include the creation of “a new power transfer method” that involves what is called 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, a doctor of electric power engineering, at the Chalmers University of Technology. “The question we posed was: how can we reduce the size, weight and price of the on-board charger.”
Because the electric motor and the inverter aren’t utilized during battery charging, the possibility was there (as the researchers recognized) to integrate them with the charger circuit and create a sort of “integrated motor and battery charger.” To word it a different way, it uses the motor and inverter in the charger circuit to increase the charging power.
“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 power 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.”
As of now, the ‘Chalmers Integrated Charger’ is still on the laboratory level, still needing further refinements in order to create a more optimal system, according to the researchers. But the design has already attracted the attention of Volvo AB, and both a Swedish and an international patent are pending.
“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 electric vehicles will succeed. And in general, I think electric transportation will become more common in the future, for example trains, trams and plug-in hybrids.”