514

Determinationof the temperature increases

∆

T

vj

of the IGBTs

•

T

vj1,min

= 50°C, T

vj1,max

= 100°C

⇒∆

T

vj1

= 50K

•

T

vj2,min

= 60°C, T

vj2,max

= 101°C

⇒∆

T

vj2

= 41K

•

T

vj3,min

= 60°C, T

vj3,max

= 125°C

⇒∆

T

vj3

= 65K

From thePC chart i

and the correction factor fro

r according to

3.0

on

corr

s5.1

t

n

−

=

the following number of cycle

can bedetermined

:

•

∆

T

vj1

= 50K, t

on1

= 11s

⇒

n

1(1.5s)

=

6

108.0

⋅

cycles andn

corr1

=0.55

⇒

6

1 corr

)s5.1(1 1

10 44.0 n n n

⋅

= ⋅

=

cycles

•

∆

T

vj2

= 41K, t

on2

= 10s

⇒

n

2(1.5s)

=

6

103.2

⋅

cycles andn

corr2

=0.57

⇒

6

2 corr

)s5.1(2 2

10 31.1 n

n n

⋅

= ⋅

=

cycles

•

∆

T

vj3

= 65K, t

on3

= 2s

⇒

n

3(1.5s)

=

6

103.0

⋅

cycles andn

corr3

=0.92

⇒

6

3 corr

)s5.1(3 3

10 28.0 n

n n

⋅

= ⋅

=

cycles

For the lifetime in cycles referenced to the bond wire connections, therefore, the

following value results from the example above:

6

The indicated number of cycles in this example is always referenced to the end value or themaximum value of

junction temperature of 125°C. As the determined junction temperatures of the sample, however, are partly below

this value, effectively then, higher numbers of cycles are to be expected, although they are not further specified in

thePC chart given.

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