Recharging circuit for modular multilevel converters

A method for recharging an energy store (102) used to drive a power semiconductor switch (100), wherein a negative terminal of the energy store (102) and a source/emitter terminal of the power semiconductor switch (100, 406, 408, 503, 616, 618, 626, 706) are connected to one another and a potential of the negative terminal of the energy store (102) is at times temporarily lower than a ground potential (106, 216) of a supply voltage, wherein a switching state of the power semiconductor switch (100, 406, 408, 503, 616, 618, 626, 706) is effected by a controller (204, 712) that jointly controls the power semiconductor switch (100) and at least one charging switch (112, 114, 122, 132, 142, 152) to recharge of the energy store (102), wherein the controller (204, 712) determines the respective potential value at the negative terminal of the energy store (102) based on a respective switching state (202) of the power semiconductor switch (100, 406, 408, 503, 616, 618, 626, 706) and wherein, by driving the at least one charging switch (112, 114, 122, 132, 142, 152) that turns on the supply voltage to the energy store (102), charging of the energy store (102) is activated as soon as the potential value of the negative terminal of the energy store (102) corresponds to the ground potential (106, 216) of the supply voltage.