Submodule for a power converter, comprising: a full bridge circuit comprising two parallel power semiconductor branches (23, 24) connected between first and second DC voltage nodes (26, 27), wherein each power semiconductor branch (23, 24) comprises two power semiconductor switches (T1-T4) connected in series, each power semiconductor switch (T1-T4) being connected in anti-parallel with a respective freewheeling diode (D1-D4), and wherein the connection points between the power semiconductor switches (T1-T4) in each power semiconductor branch (23, 24) define first and second AC voltage connections (28, 29) of the submodule, respectively; a capacitor connected in parallel to the full bridge circuit between the first and second DC voltage nodes (26, 27); and a short circuit device which includes exactly two freewheeling diodes (D1, D2), which are selected from the freewheeling diodes (D1-D4) of the submodule and are connected in anti-parallel with a respective power semiconductor switch (T1, T2) of the full bridge circuit, wherein the freewheeling diodes (D1, D2) of the short circuit device are either positioned in the same power semiconductor branch (23, 24) or connected to the same one of the first and second DC voltage nodes (26, 27), and wherein the freewheeling diodes (D1, D2) of the short circuit device have a press pack design and rated such that, when a fault occurs in the submodule, the freewheeling diodes (D1, D2) break down due to fault conditions and provide a durable, stable, low-impedance short-circuit path between the first and second AC voltage connections (28, 29) of the submodule. a full bridge circuit comprising two parallel power semiconductor branches (23, 24) connected between first and second DC voltage nodes (26, 27), wherein each power semiconductor branch (23, 24) comprises two power semiconductor switches (T1-T4) connected in series, each power semiconductor switch (T1-T4) being connected in anti-parallel with a respective freewheeling diode (D1-D4), and wherein the connection points between the power semiconductor switches (T1-T4) in each power semiconductor branch (23, 24) define first and second AC voltage connections (28, 29) of the submodule, respectively; a capacitor connected in parallel to the full bridge circuit between the first and second DC voltage nodes (26, 27); and a short circuit device which includes exactly two freewheeling diodes (D1, D2), which are selected from the freewheeling diodes (D1-D4) of the submodule and are connected in anti-parallel with a respective power semiconductor switch (T1, T2) of the full bridge circuit, wherein the freewheeling diodes (D1, D2) of the short circuit device are either positioned in the same power semiconductor branch (23, 24) or connected to the same one of the first and second DC voltage nodes (26, 27), and wherein the freewheeling diodes (D1, D2) of the short circuit device have a press pack design and rated such that, when a fault occurs in the submodule, the freewheeling diodes (D1, D2) break down due to fault conditions and provide a durable, stable, low-impedance short-circuit path between the first and second AC voltage connections (28, 29) of the submodule.