Achieving Zero Switching Loss in Silicon Carbide MOSFET

Abstract

Due to the unipolar conduction mechanism, the switching loss of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfet) is reduced significantly when compared with silicon insulated gate bipolar transistor (IGBT). This enables the use of SiC mosfet in high-frequency application. However, the switching loss could still thermally limit the upper limit of the switching frequency. Further reduction of switching loss of SiC mosfet, therefore, remains an open challenge for higher frequency applications. Based on the in-depth revelation of device physics of the switching process, accurate switching loss model is established which highlights the dependence of the switching loss on the gate driving condition. With extreme fast gate driving condition, several loss limitations can be established. The minimum turn-on loss is the energy stored in the output capacitance and the minimum turn-off loss can approach zero or the so-called zero turn-off loss (ZTL). Furthermore, zero switching loss (ZSL) is achieved when utilizing zero-voltage switching turn-on and ZTL turn-off condition. With ZSL, the upper limit of the switching frequency is no long thermally limited which is verified by co-package experimental demonstration. We believe the trailblazing concepts of SiC mosfet switching loss will provide guiding principles for device innovation, package optimization, gate driver improvement, and current possible solutions toward higher frequency applications.