A converter cell for a power converter, the cell comprising: a plurality of semiconductor devices forming a full-bridge topology in the cell with at least one switch leg comprising a plurality of the semiconductor devices connected in series, each semiconductor device comprising a switch and an anti-parallel diode; an energy storage connected across the at least one switch leg; a crowbar leg connected across the at least one switch leg, said crowbar leg comprising a plurality of series connected semiconductor crowbar switches arranged to short-circuit the energy storage when the crowbar switches are switched to conducting; and first and second AC terminals (A, B), wherein at least one of said AC terminals is connected to one of the at least one switch leg, between two of the plurality of series connected semiconductor devices of said switch leg, and connected to the crowbar leg, between two of the plurality of series connected crowbar switches of said crowbar leg, whereby the first and second AC terminals are arranged to bypass the semiconductor devices via one of said crowbar switches when said one crowbar switch is switched to conducting, wherein, the at least one switch leg consists of a first and a second switch leg, each comprising a first (T1/T3) and a second (T2/T4) semiconductor device; the plurality of series connected semiconductor crowbar switches consists of a first, a second and a third crowbar switch, and the first AC terminal is connected to the first switch leg between the first and second semiconductor devices (T1, T2) thereof, and connected to the crowbar leg between the first and second crowbar switches (C1, C2), and the second AC terminal is connected to the second switch leg between the first and second semiconductor devices (T3, T4) thereof, and connected to the crowbar leg between the second and third crowbar switches (C2, C3), and wherein a reverse crowbar switch is connected across the second crowbar switch, antiparallel to the second crowbar switch, and arranged to allow current to flow from the second terminal to the first terminal via said reverse crowbar switch when switched to conducting. a plurality of semiconductor devices forming a full-bridge topology in the cell with at least one switch leg comprising a plurality of the semiconductor devices connected in series, each semiconductor device comprising a switch and an anti-parallel diode; an energy storage connected across the at least one switch leg; a crowbar leg connected across the at least one switch leg, said crowbar leg comprising a plurality of series connected semiconductor crowbar switches arranged to short-circuit the energy storage when the crowbar switches are switched to conducting; and first and second AC terminals (A, B), wherein at least one of said AC terminals is connected to one of the at least one switch leg, between two of the plurality of series connected semiconductor devices of said switch leg, and connected to the crowbar leg, between two of the plurality of series connected crowbar switches of said crowbar leg, whereby the first and second AC terminals are arranged to bypass the semiconductor devices via one of said crowbar switches when said one crowbar switch is switched to conducting, wherein, the at least one switch leg consists of a first and a second switch leg, each comprising a first (T1/T3) and a second (T2/T4) semiconductor device; the plurality of series connected semiconductor crowbar switches consists of a first, a second and a third crowbar switch, and the first AC terminal is connected to the first switch leg between the first and second semiconductor devices (T1, T2) thereof, and connected to the crowbar leg between the first and second crowbar switches (C1, C2), and the second AC terminal is connected to the second switch leg between the first and second semiconductor devices (T3, T4) thereof, and connected to the crowbar leg between the second and third crowbar switches (C2, C3), and wherein a reverse crowbar switch is connected across the second crowbar switch, antiparallel to the second crowbar switch, and arranged to allow current to flow from the second terminal to the first terminal via said reverse crowbar switch when switched to conducting.