Redesigned power inverter promises range boost for electric vehicles
While ever-improving battery technology draws a lot of the attention when it comes to improving the range of electric vehicles, these machines feature many moving parts that play a role in their overall performance. By reimagining the way power inverters relay the current from the battery to the electric motor, scientists at the Fraunhofer Institute for Reliability and Microintegration have conjured up a new design they say works much more efficiently, and could improve EV range as much as six percent.
A power inverter is an electronic device that converts a direct current into an alternating current, and in the context of an electric vehicle, it takes electricity from the battery and converts it to run the electric motors. As an intermediary between the battery and motor, the power inverter and its transistors are made to deal with large electric currents, which causes them to increase in temperature as the vehicle is used.
To combat this, power inverters in electric cars use solid cooling elements that feature ducts resting in water, where the heat is directed and dissipated. It is these cooling elements that are the focus of the Fraunhofer scientists, who have been developing advanced transistors for inverters made of silicon carbide semiconductors, which offer a lower rate of power loss as an electric vehicle is operated.
The team set out to design cooling elements for these advanced transistors that didn't compromise on the power gains offered by the silicon carbide semiconductors. They leveraged 3D printing to produce cooling elements with much thinner walls, and positioned the transistors on a thin metal plate measuring just a few millimeters thick.
The upshot of this thinner design is the transistors are closer to the cooling water, which boosts the cooling effects. The cooling ducts double as structural components, supporting the metal plates, while the thin nature of the materials enables them to absorb stresses as the inverter heats and is cooled, by deforming ever so slightly. Additionally, flexible copper wires tie the whole thing together instead of solid copper tracks, further reducing the stress during operation.
“We expect that by optimizing the drive train in this way, the range of electric cars will ultimately be extended by up to six percent,” says Eugen Erhardt,
Erhardt notes there is still a long way to go to turn this prototype into a functional component of a production vehicle, though the researchers will get a better idea of its potential in the upcoming months. This includes testing in collaboration with Robert Bosch, and also with Porsche, which will install and test the inverter in a new drive-train designed specifically for it.