Flexible bootstrapping for power electronics circuits

A charging circuit for flexible bootstrapping in a power electronics circuit having at least one power semiconductor switch and an energy storage device that is used to control the at least one power semiconductor switch, the energy storage device and a source/emitter potential of the at least one power semiconductor switch being at the same potential, the charging circuit comprising:

• a blocking diode connected to a supply voltage that is provided by a source and is referenced to a reference potential so that the source can emit energy via the blocking diode but cannot absorb energy via the blocking diode;
• a first electrical component configured to pass a first current flow if a specified first potential difference is exceeded and a second electrical component configured to pass a second current flow if a specified second potential difference is exceeded;
• first and second bootstrap transistors having respective inputs connected to the blocking diode in a forward direction and having respective outputs connected to an upper potential of the energy storage device in the forward direction,
• at least one resistor connected between the blocking diode and a gate/base control terminal of the first bootstrap transistor, thereby causing a charging of the energy storage device as soon as the reference potential of the supply voltage is above a potential of the energy storage device, and preventing overcharging as soon as a potential difference predefined in the respective electrical component is exceeded, and thereby preventing discharging of the energy storage device by the blocking diode wherein
• a voltage upper limit in the energy storage device is maintained by the first bootstrap transistor and the first electrical component, which is designed to pass the first current flow when the specified first potential difference is exceeded, and by the second bootstrap transistor and the second electrical component, which is designed to pass the second current flow if the specified second potential difference is exceeded so that a current limit is maintained when the power semiconductor switch is activated.