Selective Soft-Switching for Thermal Balancing in IGBT-Based Multichip Systems

Although multichip systems (MCS) are the standard solution for high-power converters, uneven losses and thermal distribution affect unequal lifetime consumption. Many solutions have been proposed to mitigate these effects; however, critical thermal deviations are still observed, leading to a reduction of the overall MCS reliability. Therefore, this work proposes a selective soft-switching (SS) approach, whereby the turn-off losses of the devices are manipulated to obtain thermal balancing and increase the reliability of MCSs. As a consequence, the high current per device reduces its turn-off time, thereby slightly increasing the MCS efficiency. In addition, a pretuning-based thermal balancing approach is presented, whereby the junction temperature ( T
_j
) of the devices are sensed via collector-emitter voltage ( V
_CE
) only under reduced current conditions. To validate the proposed solutions, finite-elements modelling (FEM)-based simulation and experimental tests are conducted. Moreover, a case study demonstrates the capability of the selective SS to increase the reliability and reduce the energy consumption of MCS.