IGBT Modules - Technologies, Driver and Application (Second Edition) - page 70

scenario, the resistance also increases and the switching behaviour is
influenced accordingly.
Fig. 1.51
Integratedgate resistors to decouple IGBTs connected in parallel inamodule
1.6 Outlook
With the partial replacement of thyristors by transistors and specifically by IGBTs in the
power range up to several megawatts, a certain balance has become established, that
can also be expressed as i
Upcoming developments will now focus on factors
like the use of newmaterials like silicon carbide (SiC) and gallium nitride (GaN), in order
to increase the power per volume, i.e. the performance that can be achieved per unit of
volume. Research and development for SiC is about 10 years ahead of that for GaN, so
that SiC components are ready for series production earlier. Since several years SiC
diodes have been available commercially and become affordable, so have been used in
certain applications. Initially these diodes were used as discrete components in switch
modepower supplies (SMPS), but their scope of application is broadening all the time to
encompass the medium and high power range. Sample IGBT modules with SiC
freewheel diodes have been available for the last few years.
Alongside the development of diodes, work is progressing on active switches such as
MOSFETs, BJTs and JFETs. Manufacturers are already offering samples in small
quantities. JFETs as normally-on components offer the greatest immediate potential, as
the following overview shows:
Due to defects (even though only in small numbers) in the gate oxide of SiC
MOSFETs, operation may stop unexpectedly. The problemwith these defects
is that, as yet, there is no test available that provides a screening process to
detect the flaws, so a small percentage of components must always be
considered to be "at risk". The failure of a component can occur after a short,
medium or long period of operation, i.e. the timing is unknown. Added to that is
the low charge carrier mobility in the MOS channel, plus a temperature-
dependent drift in the threshold voltage, which can fall to values of 0V.
1...,60,61,62,63,64,65,66,67,68,69 71,72,73,74,75,76,77,78,79,80,...548
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