Semiconductor device, power conversion device, driving device, vehicle, and elevator

A power conversion device comprising:

• a transistor having a first electrode, a second electrode, and a gate electrode;
• a first capacitor having a first end and a first another end, the first end electrically connected to at least one of the first electrode and the second electrode;
• a first diode having a first anode and a first cathode, the first anode electrically connected to the first another end;
• a second capacitor having a second end and a second another end, the second end electrically connected to the first cathode;
• a sample and hold circuit electrically connected to the first cathode and the second end;
• a switch electrically connected in parallel with the second capacitor between the second end and the second another end;
• a second diode having a second anode and a second cathode, the second cathode electrically connected to the first another end and the first anode;
• a variable resistor electrically connected to the gate electrode;
• and
• a controller configured to control a resistance value of the variable resistor based on a voltage value output from the sample and hold circuit.

A power conversion device comprising:

• a transistor having a first electrode, a second electrode, and a gate electrode;
• a first capacitor having a first end and a first another end, the first end electrically connected to at least one of the first electrode and the second electrode;
• a first diode having a first anode and a first cathode, the first anode electrically connected to the first another end;
• a second capacitor having a second end and a second another end, the second end electrically connected to the first cathode;
• a sample and hold circuit electrically connected to the first cathode and the second end;
• a switch electrically connected in parallel with the second capacitor between the second end and the second another end;
• a second diode having a second anode and a second cathode, the second cathode electrically connected to the first another end and the first anode,
• wherein a power supply voltage VDD of the transistor, a capacitance C1 of the first capacitor, and a capacitance C2 of the second capacitor satisfy 15V≤(C1VDD)/(C1+C2)×Vdd.