Evaluation of Voltage-Controlled Active Gate-Drivers for SiC MOSFET Power Semiconductors

Abstract

With the development and use of Silicon-Carbide [Silicon-Carbide (SiC)] devices come a host of advantages, including higher switching frequency, improved thermal performance, and higher voltage rating. This higher switching frequency can reduce the size of the con- verter system, but is typically associated with higher dv/dt voltage slew rates that further increase electromagnetic interference (EMI) related phenomena. Conventional gate-drivers are very limited in the way that they can control this high dv/dt, and this leads to the use of active gate-drivers. This thesis will explore the use of an active voltage-controlled gate-driver for SiC devices, utilizing transiently a voltage closer to the Miller plateau than the nominal turn-on and turn-off voltage to introduce control over the switching transient. Various ap- plied voltages, and voltage sequences will be evaluated to determine their effectiveness for controlling dv/dt and their impact on switching loss. Through this work, a better under- standing of the advantages and drawbacks of an active gate-driver can be found. The main result from this work is the effective reduction in the dv/dt generated by MOSFET devices, which was attained at a lower switching loss penalty compared to conventional resistive gate-drivers operating at similar dv/dt rates. Simulation and experimental results obtained with a prototype active gate-driver circuitry were used for this evaluation.