| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the matter of a method for increasing the gate on resistance of the IGBT in a counter arm in order to control the surge voltage or oscillating voltage during reverse recovery of a circulation diode with a small current, though causing loss increase in a steady state. <P>SOLUTION: The gate threshold voltage is detected at the time of turn-off, a determination is made whether that voltage is higher than a predetermined value or not, and then gate drive conditions such as the gate on resistance at the time of next turn on or the gate on power supply voltage are switched. Since the gate conditions are switched only when the forward current of a circulation diode is small, the loss does not increase in steady state. <P>COPYRIGHT: (C)2010,JPO&INPIT |
