Title:
【発明の名称】短絡保護回路
Document Type and Number:
Japanese Patent JP2777307
Kind Code:
B2
Abstract:
A driving signal is supplied to the gate of an IGBT through a first switching element. The gate of the IGBT is grounded via a resistor and a second switching element. An output (short circuit detection signal) of an AND gate, to which the driving signal and an output signal of the IGBT are supplied, is supplied to the first switching element via a first delay circuit and supplied to the second switching element via a second delay circuit. The second delay time is larger than the first delay time. In the normal operation, the driving signal is set to an "L" level to instantaneously turn off the IGBT. The output of the AND gate is kept at the "H" level for the turn-off time and is returned to the "L" level after the turn-off operation is completed. The first switching element is turned off when the first delay time has passed after the level of the driving signal is changed. At this time, the IGBT is already turned off. When the short circuit is detected, the output of the AND gate is not returned to the "L"level if it is once set to the "H" level so that the first switching element will be turned off to isolate the IGBT. Then, the second switching element is turned on when the second delay time has passed after the detection of the short circuit, permitting charges stored in the IGBT to be discharged to turn off the IGBT.
Inventors:
KADOTA NAGATOSHI
Application Number:
JP10991392A
Publication Date:
July 16, 1998
Filing Date:
April 28, 1992
Export Citation:
Assignee:
TOSHIBA KK
International Classes:
H02H7/12; H02H7/20; H02H3/027; H03K17/082; (IPC1-7): H02H7/12; H02H7/20
Attorney, Agent or Firm:
Takehiko Suzue