Characteristics and examples of IGBT module surge voltage

L0504-Murata muRata common mode inductor 90Ω 150mA

This image illustrates the actual surge voltage characteristics observed when the U series IGBT, specifically the 6MBI450U-120, is turned off. As you can see, the magnitude of the surge voltage increases with the collector current. Higher current levels typically result in higher voltage spikes during turn-off, which can be critical for system design and component selection. The second image shows the surge voltage that occurs during the reverse recovery of the FWD (Free Wheeling Diode) in the same IGBT module. In this case, the surge voltage tends to be more significant when the collector current is relatively low—often just a fraction of the rated current. This phenomenon is important to understand because it can lead to unexpected voltage peaks that may exceed safe operating limits. It's crucial to ensure that all operating conditions remain within the RBSOA (Reverse Bias Safe Operating Area) or within the VCES (Collector-Emitter Voltage) limits to avoid potential damage to the IGBT module. Always verify your application’s parameters against these specifications before deployment.