A power electronics device, in particular a power converter, having a first power semiconductor switch, a driver circuit (49, 49a, 49b) for driving the first power semiconductor switch and an electrical auxiliary circuit arrangement (52, 52a, 52b) for supplying electrical voltage to the driver circuit (49, 49a, 49b), wherein the auxiliary circuit arrangement (52, 52a, 52b) comprises a supply capacitor (53, 53a, 53b) and an auxiliary capacitor, a normally off auxiliary semiconductor switch (55, 55a, 55b), a diode and a bootstrap diode, wherein - the auxiliary semiconductor switch (55, 55a, 55b) is connected to a reference potential connection of the first power semiconductor switch via a first connection point, - starting from the first connection point, a series connection of the diode, a second connection point and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch (55, 55a, 55b) such that, when the auxiliary semiconductor switch (55, 55a, 55b) is in the off state, the auxiliary capacitor is charged by the flow of current through the first power semiconductor switch, - the driver circuit (49, 49a, 49b) is connected to the supply capacitor (53, 53a, 53b) for its electrical voltage supply, and - the supply capacitor (53, 53a, 53b) is electrically connected by a first connection to the second connection point via the bootstrap diode and by a second connection to the reference potential connection, such that, when the auxiliary semiconductor switch (55, 55a, 55b) is in the on state and the auxiliary capacitor is at least partially charged, the supply capacitor (53, 53a, 53b) is charged by the auxiliary capacitor via the bootstrap diode, wherein the auxiliary circuit arrangement (52, 52a, 52b) comprises a drive circuit that is designed and configured to provide a control signal for switching the auxiliary semiconductor switch (55, 55a, 55b) at a control input of the auxiliary semiconductor switch (55, 55a, 55b) on the basis of a charging voltage of the auxiliary capacitor. - the auxiliary semiconductor switch (55, 55a, 55b) is connected to a reference potential connection of the first power semiconductor switch via a first connection point, - starting from the first connection point, a series connection of the diode, a second connection point and the auxiliary capacitor is arranged in parallel with the auxiliary semiconductor switch (55, 55a, 55b) such that, when the auxiliary semiconductor switch (55, 55a, 55b) is in the off state, the auxiliary capacitor is charged by the flow of current through the first power semiconductor switch, - the driver circuit (49, 49a, 49b) is connected to the supply capacitor (53, 53a, 53b) for its electrical voltage supply, and - the supply capacitor (53, 53a, 53b) is electrically connected by a first connection to the second connection point via the bootstrap diode and by a second connection to the reference potential connection, such that, when the auxiliary semiconductor switch (55, 55a, 55b) is in the on state and the auxiliary capacitor is at least partially charged, the supply capacitor (53, 53a, 53b) is charged by the auxiliary capacitor via the bootstrap diode, wherein the auxiliary circuit arrangement (52, 52a, 52b) comprises a drive circuit that is designed and configured to provide a control signal for switching the auxiliary semiconductor switch (55, 55a, 55b) at a control input of the auxiliary semiconductor switch (55, 55a, 55b) on the basis of a charging voltage of the auxiliary capacitor.