A voltage source converter comprising • a half bridge with two current valves (22, 23) connected in series and configured to be connected to opposite poles (24, 25) of a DC source/load, each said current valve comprising a semiconductor device (26, 27) of turn-off type and a rectifying diode (28, 29) connected in anti-parallel therewith, a midpoint of the half bridge between the two current valves forming an AC side of the converter and being configured to be connected to an AC load/source, and • a gate drive unit having a first gate drive part configured to control the semiconductor device of a first of the current valves and a second gate drive part configured to control the semiconductor device of the other, second of the current valves to turn on and off according to a Pulse Width Modulation pattern for creating an AC fundamental voltage and current on said AC side, each gate drive part including a control unit (35, 36) configured to control a drive member (37, 38) configured to influence gate parameters of the semiconductor device to be controlled by that gate drive part, characterized in that the converter comprises, for each current valve (22, 23), a member (41, 42) configured to firstly measure the voltage (V f) across said rectifying diode (28, 29) of the current valve at least during the half period of the AC current on said AC side when the semiconductor device (27, 26) of the other current valve is controlling the voltage on the AC side and secondly send information about the voltage measured to the control unit (35, 36) of the gate drive part associated with said other current valve controlled, that the control unit of each gate drive part (33, 34) is configured to use the voltage measured as a measure of the current on said AC side and make the control of said drive member (37, 38) thereof depending upon information about said measure so as to minimize the total switching losses associated with the turn on of the semiconductor device while still keeping the diode reverse recovery dV/dt of the diode (28, 29) of the current valve not controlling the voltage on the AC side below a maximum level allowed, and that the voltage source converter is configured to be connected on its AC side to an inductive impedance. • a half bridge with two current valves (22, 23) connected in series and configured to be connected to opposite poles (24, 25) of a DC source/load, each said current valve comprising a semiconductor device (26, 27) of turn-off type and a rectifying diode (28, 29) connected in anti-parallel therewith, a midpoint of the half bridge between the two current valves forming an AC side of the converter and being configured to be connected to an AC load/source, and • a gate drive unit having a first gate drive part configured to control the semiconductor device of a first of the current valves and a second gate drive part configured to control the semiconductor device of the other, second of the current valves to turn on and off according to a Pulse Width Modulation pattern for creating an AC fundamental voltage and current on said AC side, each gate drive part including a control unit (35, 36) configured to control a drive member (37, 38) configured to influence gate parameters of the semiconductor device to be controlled by that gate drive part,