Conduction Time Variation-Based Active Thermal Control Method for Si and SiC Hybrid Switch

The Si IGBT and SiC MOSFET hybrid switch (Si/SiC HyS) is becoming an alternative solution of the pure Si IGBT or pure SiC MOSFET due to the superior performance on low switching loss, low device cost, and high current carrying capability. In the Si/SiC HyS, all the switching losses are produced by the small current rated SiC MOSFET, thus resulting a higher device junction temperature. The unbalanced device junction temperature will limit the maximum output power of the Si/SiC HyS-based converter and also reduce the converter reliability. In order to solve this problem, the conduction time variation-based active thermal control (CTV-ATC) is proposed in this paper. The SiC MOSFET device junction temperature can be regulated actively by adjusting the conduction loss of SiC MOSFET. To validate the effectiveness of the proposed CTV-ATC, experiments were conducted on a Si/SiC HyS-based buck converter prototype. The experimental results show that by using the proposed CTV-ATC, the junction temperature of Si IGBT and SiC MOSFET can be regulated and reach a balanced state. The maximum output power of the Si/SiC HyS-based converter is improved by 5.9%.