Stuttgart scientists set “new standard” for compact LEV chargers and shortened charge cycles
Researchers with the Institute of Robust Power Semiconductor Systems (ILH) and the Institute of Power Electronics and Electrical Drives (ILEA) at the University of Stuttgart have prototyped a new charging platform that has achieved a “new standard” for LEV charging efficiency and compactness.
The joint R&D project analysed the markets’ various commercially available chargers for electric bikes and electric scooters, then compared with the charging technology available to the laptop segment, for example. In carefully dissecting the products the teams looked at the properties of Gallium-nitride (GaN), which has just come into play as part of an effort to promote fast charging in mobile phones. Chips made with this material can deliver high power at small volume, though temperature of operation has been an obstacle to overcome.
In developing the technology for an light electric vehicle application (LEV) the researchers first built six custom-designed power stages based on GaN into a prototype. Refining the concept, the scientists hit the required charging specifications of a power rating above 150W in a unit that measures about half the size of most commercially sold chargers for these vehicles. They achieved a power density of 1.6W/litre.
The researchers outline that, while batteries have been getting smaller, lighter and the drivetrains more efficient, charging infrastructure has neglected to keep the pace. One challenge standing between progress has been thermal regulation, with heat having to be contained safely within the housing of a charger. Overcoming this in their prototype, the researchers have found an optimum placement of component parts to ensure electrical integrity and avoid electro-magnetic interferences.
Innovations such as wireless charging are creeping closer to becoming viable for the LEV segment, with one example prototype visible at the recent IAA Mobility event.
Photo: University of Stuttgart /ILH
