Gate Control Optimization of Si/SiC Hybrid Switch Within Wide Power Rating Range

The concept of the cost-effective SiC/Si hybrid switch consisting of a high power Si IGBT as the main switch and a low power SiC MOSFET as the auxiliary switch is reported to achieve a better tradeoff between its improved electrical performance and cost. However, the auxiliary SiC MOSFET undertakes more switching loss and conduction loss than the main IGBT at the inappropriate gate control patterns. It leads to the SiC MOSFET's junction temperature considerably higher than that of the main IGBT due to its small chip size and high thermal resistance, which results in a serious risk of overheating and reliability degradation of the SiC MOSFET inside the cost-effective SiC/Si hybrid switch. In this paper, we propose a weighted average junction temperature method to keep the junction temperature of both devices within the specified temperature limit. It based on the junction temperature of the two devices in the hybrid switch varies with their gate signal's delay time and the power rating. Using the weighted average junction temperature method, the excellent thermal performances of the SiC/Si hybrid switch are demonstrated in a 20kHz DC/DC hybrid switch boost converter at various load conditions.