How asymmetric busbar design causes symmetric switching behavior of paralleled IGBT modules

Inhalt:
Paralleling of IGBT modules is of special interest because of its ease to adapt the individual systems current rating, just by choosing the amount of devices. Especially half-bridge modules like the XHP(Exp TM) 3 or the EconoDUAL (Exp TM) are well suited for such parallelisation purposes. In order to maintain the performance of parallelised modules by negligible derating needs a well-defined inverter environment is mandatory. This includes an appropriate gate drive strategy and its cabling as well as an inductively uniform designed DC busbar and PCB layout, respectively. But inductively uniform does not necessarily means a geometrical symmetrical design at all. In this paper the effect of an asymmetric DC busbar design on the current balance during turning-on two IGBT modules in parallel is shown.