| 摘要 |
PROBLEM TO BE SOLVED: To prevent a gate power supply circuit that feeds power to a gate drive circuit from being secondarily broken when a power device and its gate drive circuit are broken. SOLUTION: A resistor 141 detects AC output currents outputted to the gate drive circuits 210, 220, a diode D3 rectifies an AC signal obtained at the resistor 141 and converts it to a DC signal, a filter circuit 142 smoothes the rectified DC signal, a comparator 143 compares the smoothed DC signal with a prescribed reference value, and when the DC signal exceeds the reference value, the comparator outputs a signal for stopping the supply of power to the gate drive circuits 210, 220 for the reason that an overload current has flowed, thereby preventing the gate power supply circuit 100a from being secondarily broken by the overload current generated due to breakages of the power devices 310, 320. COPYRIGHT: (C)2005,JPO&NCIPI
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