| Abstract |
The calculation of the right fuse for a
power semiconductor equipment is requiring more
and more sophisticated calculation and simulation.
Due to new semiconductors like IGBT/IGCT fuses
are undergoing high current duty cycle, high
frequency and end users are requiring longer fuses
life time and lower I²t.
In order to face this new request and to understand
how the fuse behaves under high duty cycle and/or
high frequency, we have developed a method to
evaluate thermal and electrical behavior of fuses in
parallel and/or subject to high frequencies.
This method consists in a coupling between two
simple models for fuse and its surrounding.
First is thermal model, including thermal resistance,
capacitances and generators. This model allows to
take into account fuse itself and also its
connections, heat generated by semiconductor, and
surrounding. The parameters for the thermal
characteristics of the fuse have been expressed in a
very simple way.
Second is a simulation of the circuit, using HOER
and LOWE’s formula [1] in order to evaluate
resistance, self and mutual inductances for each
component of the circuit. A so-called InCa software
[2] is used in this way.
Finally both models are coupled in a solversoftware
which gives temperature of each
component and current in each conductor. These
results are used for the fuse determination, in
addition of consideration of I²t for protection and
duty-cycles for life-duration.
An example of modellisation will be presented and
also how is was used for customer application. |
