Hitachi IGBT Module Application Manual
5.8.4 Short-circuit Current and Gate Voltage Increase
Collector voltage increases with short-circuit current, at the same time gate voltage increase due to dv/dt
current flows to gate through reverse transfer capacitance ( C
res
). The increase in gate voltage can be
estimated by examination of the Q
res
electric charge characteristics. (Refer to Figure 51.)
Figure 51. Example of Gate Charge Characteristics
Figure 52 represents a standard drive circuit for an IGBT and its connection. When the IGBT’s collector
voltage increases due to short circuit current,
Q
res
conducts to the gate through
C
res
.
Figure 52. Dependency of Gate Voltage upon C
res
In this case, gate current ( i
gsc
) can be calculated as shown in Equation 42.
Equation 42:
i
gsc
= (v
ge
(i) - V
GP
’ )/ R
G
and Q
res
can be calculated using Equation 43:
47
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