Patent ID: 8194429

Claim:
An inverter comprising: two input lines to which a voltage of a fixed polarity is supplied in operation of the inverter; an inverter bridge connected between the input lines and including at least one half-bridge, each half-bridge comprising two normally conductive gate-controlled semiconductor switches, such that the complete inverter bridge is conductive between the input lines, if no control voltage is applied to the gates of the semiconductor switches; a controller which supplies control voltages to the gates of the gate-controlled semiconductor switches of the inverter bridge in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of at least some of the semiconductor switches of the inverter bridge in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines, the DC voltage source comprising a storage unit for electric charge, and a charging unit comprising an input side and an output side, wherein a DC current flowing through the input side of the charging unit causes a DC current through the output side of the charging unit, the charging unit, at its input side, is connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch which is conductive, if no control voltage is applied to its gate, and the charging unit, at its output side, is connected to the storage unit, and the storage unit is connected to the gate of the further normally conductive gate-controlled semiconductor switch such that the further normally conductive gate-controlled semiconductor switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.