Round busbar concept for 30 nH, 1.7 kV, 10 kA IGBT non-destructive short-circuit tester

Design of a Non-Destructive Test (NDT) set-up for short-circuit tests of 1.7 kV, 1 kA IGBT modules is discussed in this paper. The test set-up allows achieving short-circuit current up to 10 kA. The important objective during the design of the test set-up is to minimize the parasitic inductance and assure equal current sharing among the parallel connected devices. Achieving of a low inductance level is very challenging due to the current and voltage ratings, the presence of series and parallel protection systems and the required access for a thermal camera. The parasitic extractor Ansys Q3D is used to estimate the parasitic inductances during the design. A new concept of round-shaped, low inductive busbars for an NDT set-up is proposed. Simulation results verified that both reduction of overall inductance and good uniformity in current sharing among parallel devices are achieved by utilizing a circular symmetry. Experimental validation of the simulation was performed using a preliminary set-up. Further, this concept can be implemented in the design of the busbars for the power converters, where the parallel connection of the switching devices is applied to obtain higher current levels.