Power converter assembly with potential separation, - having a first input and output (uU, uV, uW), - having a second input and output (Udc) and - having a bidirectional power converter (B2C), with an AC input and output and a DC input and output - wherein the DC input and output of the bidirectional power converter are connected to the second input and output (Udc) of the power converter assembly, - having a smoothing reactor (Lf) in series with the second input and output or having a smoothing capacitor (Cf) parallel to the second input and output (Udc) and a smoothing reactor (Lf) in series with the parallel circuit from the smoothing capacitor and the second input and output (Udc), - having a direct converter - having a transformer and - having a current sensor for detecting a reactor current (iL) through the smoothing reactor (Lf), - wherein a first input and output of the direct converter is connected to the first input and output (uU, uV, uW) of the power converter assembly, - wherein a second input and output of the direct converter is connected to a primary side of the transformer, - wherein a secondary side of the transformer is connected to the AC input and output of the bidirectional power converter (B2C), - wherein the power converter assembly has a current sensor for detecting a primary current (iP) through the primary side of the transformer and characterised in that - the power converter assembly has a means for comparing the magnitude of the primary current through the primary side of the transformer and of the reactor current through the smoothing reactor, both currents arithmetically transformed on one of the two sides of the transformer, and wherein the power converter assembly is configured to switch from charging the smoothing reactor (Lf) to discharging the smoothing reactor (Lf), when the current through the smoothing reactor (iL) and the current (iP) through the primary side of the transformer, both currents transformed on one of the two sides of the transformer, have an equal magnitude. - having a first input and output (uU, uV, uW), - having a second input and output (Udc) and - having a bidirectional power converter (B2C), with an AC input and output and a DC input and output - wherein the DC input and output of the bidirectional power converter are connected to the second input and output (Udc) of the power converter assembly, - having a smoothing reactor (Lf) in series with the second input and output or having a smoothing capacitor (Cf) parallel to the second input and output (Udc) and a smoothing reactor (Lf) in series with the parallel circuit from the smoothing capacitor and the second input and output (Udc), - having a direct converter - having a transformer and - having a current sensor for detecting a reactor current (iL) through the smoothing reactor (Lf), - wherein a first input and output of the direct converter is connected to the first input and output (uU, uV, uW) of the power converter assembly, - wherein a second input and output of the direct converter is connected to a primary side of the transformer, - wherein a secondary side of the transformer is connected to the AC input and output of the bidirectional power converter (B2C), - wherein the power converter assembly has a current sensor for detecting a primary current (iP) through the primary side of the transformer and - the power converter assembly has a means for comparing the magnitude of the primary current through the primary side of the transformer and of the reactor current through the smoothing reactor, both currents arithmetically transformed on one of the two sides of the transformer,