Experimental evaluation of switching characteristics, switching losses and snubber design for a full SiC half-bridge power module

This paper analyzes the switching performance of the full SiC half-bridge power module BSM120D12P2C005 from Rohm Semiconductor. It investigates if the combination of a DC snubber and a turn-off snubber helps to reduce sufficiently the electrical stresses on hard-switching power modules. Simulations in LTspice IV and laboratory experiments give the basis for the analysis. Standard double-pulse tests of the module are conducted at different drain currents. This makes it possible to analyze the switching characteristics and the total switching losses of the SiC module. Simulations in LTspice are used in order to investigate if the use of suitable snubber circuits improves the switching transients. The performance of these snubbers is tested and verified through laboratory experiments. It is shown in both simulations and laboratory experiments that a simple and well-known DC snubber circuit for half-bridge configurations attenuates ringing without reducing the voltage overshoot. In order to suppress this extensive voltage overshoot to an acceptable level during device turn off, a turn-off snubber must be added to the circuit. It is found that this solution does not increase the switching losses significantly.