122

Areas of dissipation losses for an IGBTanda diode

Maximum junction temperatureT

vj,max

•

Maximum permitted temperature of the semiconductor in DC-operation. Bears

practically no relevance for the thermal design.

Junction temperatureduring switchingT

vj,op

•

Defined temperature region for the switching operation of semiconductors.

Relevant parameter for the thermal designand to calculate lifetime.

Turn-on energyE

on

•

Energy generated inside the IGBT during the turn-on of a single collector

current pulse. The time span t

Eon

to determine E

on

starts at that moment where

I

C

has risen to 10% of its nominal value and ends where U

CE

has dropped to

2% of its nominal value. E

on

isdefined as:

dt )t(i)t(u

E

c

t

0

ce

on

Eon

⋅

=

∫

In practiceE

on

is determinedwith a digital oscilloscope (chapte

.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

on

. Alternatively the mathematical analysis may

be done on a computer after exporting themeasured data.

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