Comparative Analysis Based on Thermal Models and Device Losses for the SiC-based ANPC Topologies

The silicon carbide (SiC) devices are getting popular due to their numerous advantages for the modern power electronic applications. Further, in order to cater the limitation of the high cost of these devices and to enhance their application demand, the topologies with hybrid utilization of the Si and SiC devices are proposed in the literature. In such topologies, the device losses are distributed unevenly which plays a vital role in converter operation. In this paper, such Si and SiC based hybrid topologies are analyzed for the converter operating conditions such as junction temperatures and device losses. The paper initially considers the conventional thermal model and evaluates the effect of uneven distribution of losses on their junction temperatures. Then, the actual heat sink model is simulated using the FEM simulations to verify the conventional thermal model. Based on these results, the issues in application of the conventional thermal model for the converter design of the topologies with uneven loss distribution are identified and the modified analytical approach is proposed. Moreover, a detailed procedure for accurate determination of the converter operating conditions using the parameters of the designed experimental prototypes for the considered topologies is presented. Finally, the results are given to compare the difference between the conventional and proposed approach for the considered topologies.