Flexible bootstrapping for power electronics circuits

A method for flexible bootstrapping in a power electronics circuit, in which an energy storage device (102) used for controlling a power semiconductor switch (100) and a source/emitter potential of the power semiconductor switch (100) are at the same potential, wherein a blocking diode (112) is connected to a supply voltage (106), which is provided by a source and is referenced to a reference potential, in such a way that the source can only emit, but not absorb, energy via said blocking diode (112), and the blocking diode (112) is followed by at least one bootstrap transistor (114, 804, 1114, 1124), the drain/collector input of which is connected to the blocking diode (112) and the source/emitter output to an upper potential of the energy storage device (102), wherein at least one electrical component (802), which is designed to also pass a current flow in the blocking direction if a predefined potential difference is exceeded, if the bootstrap transistor (114, 804, 1114) is an n-channel field effect transistor (114) or an npn-bipolar transistor (804, 1114), is connected with an input of the electrical component (802) in the blocking direction to a gate/base control terminal of the bootstrap transistor (114, 804, 1114) and with an output of the electrical component (802) to a terminal of the energy storage unit (102) located at the source/emitter potential of the power semiconductor switch (100), and if the bootstrap transistor (1124) is a p-channel field effect transistor (1124) or a pnp-bipolar transistor, said electrical component is connected in the blocking direction with an input of the electrical component (1122) to an upper potential of the energy storage device (102) and with an output of the electrical component (1122) to a gate/base control terminal of the bootstrap transistor (1124), and wherein correspondingly with an n-channel field effect transistor (114) or an npn-bipolar transistor (804, 1114) as the bootstrap transistor (114, 804, 1114) at least one resistor (812, 822, 1128) is arranged between a potential of the supply voltage (106) and the gate/base control terminal of the bootstrap transistor (114, 804, 1114) and, with a p-channel field effect transistor (1124) or a pnp bipolar transistor as the bootstrap transistor (1124), said resistor is arranged between the source/emitter potential of the power semiconductor switch (100) and the gate/base control terminal of the bootstrap transistor (1124), which causes a charging of the energy storage device (102) as soon as the potential of the supply voltage (106) is above a potential of the energy storage device (102), and which prevents overcharging as soon as the potential difference predefined in the electrical component (802) is exceeded, and thereby prevents discharging of the energy storage device (102) by the blocking diode (112),

• characterized in that
• a voltage upper limit in the energy storage system (102) is maintained by means of a first bootstrap transistor (1224) and a first electrical component (1226), which is designed to pass a current flow when a first predefined potential difference is exceeded, and by means of a second bootstrap transistor (1225) and a second electrical component (1227), which is designed to pass a current flow if a second predefined potential difference is exceeded, a current limit is maintained when the power semiconductor switch (100) is activated.