Dynamic paralleling problems in IGBT module construction and application

IGBTs have seen a continuous gain of importance since their introduction into the market, not only from the installed number of devices but also from the served applications. The expansion from small single device applications through industrial inverters up to large traction motor drives and HVDC converters have been possible mainly thanks to the fact that the IGBT devices can be paralleled and in addition series connected to achieve the high currents needed to realize multi megawatt applications. However, the demand for increasing power combined with the requirement of increasing reliability needs further understanding of the limiting mechanisms for stable paralleling and predictable sharing between the devices. New semiconductor generations have been developed to achieve lower losses and higher current densities, and some newly introduced properties have lead to changes of the behaviour in parallel setups. The following paper gives an overview of the issues to overcome when designing large scale paralleled IGBT devices and applications.