IGBT Modules - Technologies, Driver and Application (Second Edition) - page 346

8.2.3 Gatedrive inparallel connection
Fig. 8.8
Gatedrives for parallel connection
The gate drive takes a central role in static operation and a crucial role in dynamic
operation. In static operation, only the peak value of the gate emitter voltage plays a
role, but dynamic current mismatching is very strongly influenced by the IGBT gate
The dynamic behaviour in parallel connection depends very much on the type of gate
drive used. The threemainmethods of controlling IGBTmodules in parallel connection
are described below. Direct gatedrive inparallel connection
Because of its history, direct gate drive is now themost commonly used type of drive for
parallel connections. The design of the gate drive unit (GDU) is quite simple. The
IGBTs, connected in parallel, are controlled by a central gate drive. Direct gate drive
therefore needs a powerful output stage. Each of the gates has its own gate resistor,
together with an emitter resistor, which absorbs the dynamic compensating current in
the auxiliary emitter. If saturation voltage monitoring (chapter
is applied, it is
sufficient to connect this to one IGBT collector. However, if Active Clamping is used
each IGBT should have its own protection. This is strongly dependent on
the individual commutation paths and, in turn, the stray inductance.
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