Impact of parasitic elements on the power dissipation of Si superjunction MOSFETs, SiC MOSFETs, and GaN HEMTs

Abstract

In power conversion systems, where higher switching frequencies are required for miniaturization, the selection of power switches with lower power loss becomes essential for achieving better efficiency. At higher switching frequencies, the parasitic elements of the power switch largely dictate the efficiency of the power electronic system. Hence, it becomes critical to investigate the impact of parasitic losses on overall efficiency. The parasitic components of the power transistor vary with the semiconductor technology and thus effects the power converter system differently. This paper compares three power switch technologies: Silicon (Si) based Superjunction (SJ) power MOSFET, Silicon Carbide (SiC) based power MOSFET, and Gallium Nitride (GaN) based HEMT, for three different voltage ratings: 650 V, 900 V, and 1200 V. The effect of the parasitic components on the converter efficiency has been demonstrated using an inductive clamped loading circuit implemented in LTSPICE. The results demonstrate that at a frequency of 200 kHz, the total power loss for 650 V power switches was 44 W, 108 W, and 127 W for GaN, SiC, and SJ, respectively. At 500 kHz, the total power loss for 1200 V power switches was 622 W and 720 W for GaN and SiC, respectively. Overall, the GaN technology provides lower power losses than SiC and SJ due to lower parasitic capacitance and on-resistance, indicating the potential of GaN power devices for higher voltage applications. This comparison enables a power engineer to select an appropriate power switch that ensures the best possible efficiency for a specific application.