A Converter (1a.1c) for single-phase and three-phase Operation which comprises a three-phase rectifier to which three coils (La, Lb, Lc) are connected on the mains side is described. A first coil (La) is provided on the mains side with a switch (S) which connects the first coil (La) to the mains during three-phase Operation and connects it via a capacitor (C) either to the lower end (FP) of the rectifier or on the mains side to another coil (Lb, Lc) during single-phase Operation. In addition, a d.c. voltage supply and a battery charger (5a.5c) which comprise the Converter (1a.1c) according to the invention are described.