Short charging times are essential for the acceptance of battery-powered vehicles. As a result, three-phase on-board chargers are increasingly being installed in electric vehicles as they significantly reduce charging times compared to single-phase charging circuits.

However, conventional three-phase on-board charger circuits (OBC) inherently generate significant common-mode interference that can disrupt the functionality of other electronic devices. Electrical isolation in the power path and distinct EMC filters are usually required to manage this interference in accordance with the standards. The problem: The material costs of the isolating power circuits, as well as their electrical operating losses, are higher than for non-isolated circuits, which also enable reductions in weight. The same applies to the filters used. The invention is based on the modification of a basic circuit in the OBC power path – this makes it possible to do without the isolating power circuit including the power transformer and replace it with a simple non-isolated DC/DC converter. Savings can also be achieved with regard to the EMC filter, thus enabling the power density and efficiency of the OBC to be increased. The invention additionally allows for the full use of 650V switches such as silicon MOSFETs or, in the future, GaN transistors.