Device and method for charging an electrical energy store from a three-phase AC voltage source

The invention relates to a device (100) for charging an electrical energy store (B) from a three-phase AC voltage source (U1, U2, U3), said device having: -a converter device (20) electrically connected to the AC voltage source (U1, U2, U3) and with three half-bridges (H1, H2, H3), each having two series-connected switches (S1, S2; S3, S4; S5, S6), wherein an inductor (L1, L2, L3) is connected electrically between a respective node point of two switches (S1 . . . S6) of one of the half-bridges (H1, H2, H3) and a respective phase of the AC voltage source (U1, U2, U3); -a buck converter device (TS) electrically connected to an intermediate circuit capacitor (C1) of the converter device (20), wherein a switch (STS) of the buck converter device (TS) is cyclically switched in a charging mode of the device (100) and is open in a regular mode of the converter device (20); and -a switch (SF) by means of which the buck converter device (TS) can be bypassed in regular mode of the converter device (20); -wherein, depending on the phase voltages of the AC voltage source (U1, U2, U3) and currents through the inductors (L1, L2, L3), the switch (STS) of the buck converter device (TS) and the switches (S1 . . . S6) of the half bridges (H1, H2, H3)of the converter device (20) can be switched by means of a control device (10) in such a manner that a charging current for the electrical energy store (B) drawn from the AC voltage source (U1, U2, U3)in order to charge the electrical energy store (B) is formed such that each phase current of the AC voltage source (U1, U2, U3) is substantially sinusoidal, the phase currents being substantially in phase with the corresponding phase voltages of the AC voltage source (U1, U2, U3).