# IGBT Modules - Technologies, Driver and Application (Second Edition) - page 135

123
Fig. 3.6
Timeperiod todetermine the turn-onenergy
Turn-off energyE
off
Energy generated inside the IGBT during the turn-off of a single collector
current pulse. The time span t
Eoff
to determine E
off
starts at that moment where
U
CE
has risen to 10% of its nominal value and ends where I
C
has dropped to
2% of its nominal value. E
off
isdefined as:
dt )t(i)t(u
E
c
t
0
ce
off
Eoff
=
Eq. 3.2
In practiceE
off
is determinedwith adigital oscilloscope.With this u
CE
(t) and i
C
(t)
are traced. Subsequently themaths function is used to build the time integer of
the product of both traces. The maximum value of the integer then represents
the value of E
off
. Alternatively the mathematical analysis may be done on a
computer after exporting themeasured data.
Reverse recovery energyE
rec
Energy generated inside the diode during the diode turn-off. E
rec
is determined
by the time span beginningwhenU
R
has risen to 10% of its nominal value and
endingwhen I
RM
has dropped to 2%of its nominal value. E
rec
is definedas:
dt )t(i)t(u
E
F
t
0
R
rec
Erec
=
Eq. 3.3
In practice E
rec
is determinedwith a digital oscilloscope.With this u
R
(t) and i
F
(t)
are traced. Subsequently themaths function is used to build the time integer of
the product of both traces. The maximum value of the integer then represents
the value of E
rec
. Alternatively the mathematical analysis may be done on a
computer after exporting themeasured data.
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