Patent ID: 9692405
Date: 2017-06-27
CPC Classifications: H01L,H03K,Y02B

Claim:
1. A switching circuit comprising: a first IGBT; a second IGBT; a wiring in which a parallel circuit of the first IGBT and the second IGBT is inserted; and a control circuit configured to switch the first IGBT and the second IGBT by controlling gate currents of the first IGBT and the second IGBT, wherein the control circuit includes a first switching element including a first main electrode and a second main electrode, the first switching element controlling a current between the first main electrode and the second main electrode, the first main electrode connected to a reference potential, and the first switching element configured to control the gate current of the first IGBT in accordance with a potential of the second main electrode, a second switching element including a third main electrode and a fourth main electrode, the second switching element controlling a current between the third main electrode and the fourth main electrode, the third main electrode connected to the reference potential, and the second switching element configured to control the gate current of the second IGBT in accordance with a potential of the fourth main electrode, and a third switching element connected between the second main electrode and the fourth main electrode, and the control circuit is configured to turn on both the first IGBT and the second IGBT at a turn-on timing, and turn off both the first IGBT and the second IGBT at a turn-off timing, when a current flowing through the wiring is larger than a threshold, turn on a first target IGBT as one of the first IGBT and the second IGBT at the turn-on timing, turn off the first target IGBT at the turn-off timing, and turn off a second target IGBT as the other of the first IGBT and the second IGBT prior to the turn-off timing, when the current flowing through the wiring is smaller than the threshold, turn on the first switching element and the second switching element with the third switching element on, when the gate currents are caused to simultaneously flow through the first IGBT and the second IGBT, and turn on that one of the first switching element and the second switching element which controls the first target IGBT with the third switching element off, when the gate current is caused to flow through the first target IGBT and the gate current is not caused to flow through the second target IGBT.