Switch system

A switch system comprising:

• a semiconductor switch having a control terminal, a first main terminal, and a second main terminal;
• a voltage clamping element connected to the semiconductor switch in parallel;
• an active clamping circuit connected between the control terminal and the first main terminal of the semiconductor switch;
• a first control unit configured to control the semiconductor switch;
• and
• a second control unit configured to control the active clamping circuit,
• the active clamping circuit including:
• a first diode having a first anode and a first cathode and causing breakdown upon application of voltage between the first main terminal and the second main terminal of the semiconductor switch;
• a second diode having a second anode and a second cathode, the second anode of the second diode being connected to the first anode of the first diode;
• and
• a control switch connected between the first anode of the first diode and the control terminal of the semiconductor switch,
• the control switch being a pnp transistor having a base, a collector, and an emitter, the emitter of the pnp transistor being connected to the second cathode of the second diode, the collector of the pnp transistor being connected to the control terminal of the semiconductor switch,
• the second control unit including:
• a first resistor connected between the base and the emitter of the pnp transistor;
• a second resistor connected to the base of the pnp transistor and connected to the first resistor in series;
• a field effect transistor having a gate, a drain, and a source and connected between the second resistor and the second main terminal of the semiconductor switch;
• and
• a delay circuit connected between the first control unit and the gate of the field effect transistor,
• the delay circuit including:
• a gate resistor connected between the first control unit and the gate of the field effect transistor;
• and
• a capacitor connected between the gate and the source of the field effect transistor,
• a breakdown voltage of the first diode being smaller than a clamp voltage of the voltage clamping element.

A switch system comprising:

• a semiconductor switch having a control terminal, a first main terminal, and a second main terminal;
• a voltage clamping element connected to the semiconductor switch in parallel;
• an active clamping circuit connected between the control terminal and the first main terminal of the semiconductor switch;
• a first control unit configured to control the semiconductor switch;
• and
• a second control unit configured to control the active clamping circuit,
• the active clamping circuit including:
• a first diode having a first anode and a first cathode and causing breakdown upon application of voltage between the first main terminal and the second main terminal of the semiconductor switch;
• a second diode having a second anode and a second cathode, the second cathode of the second diode being connected to the first cathode of the first diode;
• and
• a control switch connected between the first anode of the first diode and the control terminal of the semiconductor switch,
• the control switch being a field effect transistor having a gate, a drain, and a source, the drain of the field effect transistor being connected to the first anode of the first diode, the source of the field effect transistor being connected to the control terminal of the semiconductor switch,
• the second control unit including:
• a capacitor having a first terminal and a second terminal, the first terminal of the capacitor being connected to the gate of the field effect transistor, the second terminal of the capacitor being connected to the first cathode of the first diode and the second cathode of the second diode;
• and
• a Zener diode having a third anode and a third cathode, the third cathode of the Zener diode being connected to the first terminal of the capacitor and the gate of the field effect transistor, the third anode of the Zener diode being connected to the source of the field effect transistor.