Comparative Study on Stray Inductance and Current Sharing of a 90kW Inverter Using Multiple Discrete IGBT Devices in Parallel

With the emergence of new generation IGBT and the commercialization of SiC technology, there is a growing interests in adopting discrete power semiconductor devices to develop high-power converter products due to their prevalent cost advantage over power modules. This paper presents an empirical study on stray inductance and current sharing in discrete IGBT paralleling through the development and test of a 90kW inverter prototype. In this prototype, each switch comprises 4 discrete IGBT devices in parallel. Two different layout designs featuring different way of current commutation route are proposed and compared. Stray inductance is extracted from Q3D and further analyzed through semi-SPICE simulations in PLECS. Prototypes are made and double pulse tests are conducted to measure the current sharing among the parallel devices during switching transients. The good match of experimental results with the simulation validates the effectiveness of semi-SPICE modelling for current sharing evaluation. The comparative study confirmed the advantages of using a PCB laminated bus layout structure for multiple paralleling of discrete IGBT devices.