© by SEMIKRON
/ 2017-09-07 /
Technical Explanation
/ SKiiP
®
4
Page 61/73
Figure 7.14: Probability of a failure during operation time.
The evaluation of the failure rate for different temperatures shows that its expected failure rate roughly
doubles for a 20 C increase in operating temperature (see Figure 7.15).
Figure 7.15: SKiiP driver failure rate temperature dependence calculated according to
SN29500
The less stress a device is subjected to, the less likely it is to fail. Low operation time, low current, low
temperature and low dc-link voltage prolong the component’s life and, hence, reduce the failure rate.
Therefore, the design objective for the individual equipment represents a suitable compromise between
exploiting the electrical and thermal capability of a device and obtaining an acceptable failure rate and life
time expectation.
The following temperature rating is recommended for the SKiiP4 systems:
•
Power section: It is necessary to ensure by calculations and measurements that the recommended IGBT
and diode junction temperatures are not exceeded at maximum overload conditions stipulated by the
application. The recommended maximum junction temperature under worst case conditions is 150°C
being 25°C lower than the maximum permitted chip temperature of 175°C. That margin provides a
certain minimum to ensure a reliable operation. Dedicated calculations shall be carried out by the
SEMIKRON simulation tool SEMISEL which is available on the SEMIKRON homepage www.semikron.com.
Load cycles and cooling conditions can be adapted to meet the application conditions. The measurement