Device and method for charging an electric energy store from a three-phase ac voltage source

Abstract

The invention relates to a device () for charging an electric energy store (B) from a three-phase AC voltage source (W, W, W), having, in each phase of the AC voltage source (W, W, W):—a step-down converter (TS. . . TS) with a switch (STS. . . STS);—a diode (FLD) connected in parallel to the step-down converter (TS. . . TS); and—a converter (U) which is connected to the step-down converter (TS. . . TS) and which comprises at least one first half bridge (H) with two serially connected switches (S, S), an inductor (L) being connected between a connection point of the two switches (S, S) of the first half bridge (H) and the step-down converter (TS. . . TS);—wherein a current direction across the inductor (L) is set by means of a rectifier (D. . . D) in the step-down converter (TS. . . TS); and—the switches (STS. . . STS) of the step-down converter (TS. . . TS) and at least one second switch (S) of the first half bridge (H) of the converter (U) can be switched by means of a controller () dependent on the voltages of the AC voltage source (W, W, W) and a current flowing through the inductor (L) such that a current drawn from the AC voltage source (W, W, W) in order to charge the electric energy store (B) can be generated in such a manner that a substantially sinusoidal current is drawn from each phase of the AC voltage source (WW, W), the current and the corresponding voltage of the AC voltage source (W, W, W) being substantially in phase in each said phase.