3.9 Stray inductance
Simplified example of stray inductances in the commutationpath
During the switching of power semiconductors the parasitic stray inductance L
special role in the current commutation path. Depending on the size of the stray
inductance and the gradient of the current change slope
the components are
stressed additionally or, at the extreme, it may come to the destruction of the
semiconductor. The stray inductance in the commutationpath ismade up of:
The internal module stray inductance (in
combined as the two
), which are usually quoted in the datasheet
of the IGBTmodul
The stray inductance L
resulting from the construction of the DC-bus.
The inductance canbeascertainedby simulation and/ormeasurement.
The stray inductance of the DC-bus capacitors L
which is generally
quoted in the capacitor’s datasheet.
The stray inductance is not influenced by the inductance of the Load L
and this does
therefore not become part of the consideration.
Typically only the maximum value of the stray inductance of a single switch or half-bridge is quoted in the
datasheet. In the shown example the datasheet would list the value of
assume that all threehalf-bridges have identical inductances).