IGBT short circuit withstand capability
The IGBT short-circuit withstand time is related to its transconductance or gain and the thermal capacity of the IGBT chip. Higher gains result in higher short-circuit currents within the IGBT, so it is clear that lower gain IGBTs have lower short-circuit levels. However, higher gains also result in lower on-state conduction losses, and trade-offs must be made. The development of IGBT technology is contributing to the trend of increasing the short-circuit current level, but reducing the short-circuit withstand time. In addition, advances in technology have led to smaller chip sizes, reduced module size, but reduced heat capacity and further reduced tolerance time.
In addition, it has a large relationship with the IGBT collector-emitter voltage, so the parallel trend of industrial drive tends to higher DC bus voltage levels further reduces the short circuit withstand time. In the past, this time range was 10 μs, but in recent years the trend has been in the direction of 5 μs 3 and under certain conditions down to 1 μs.
In addition, the short-circuit withstand time of different devices is also quite different, so for IGBT protection circuits, it is generally recommended to build more margin than the rated short-circuit withstand time.
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