An Analytical Switching Loss Model for a SiC MOSFET and Schottky Diode Half-Bridge Based on Nonlinear Differential Equations

Abstract

An accurate analytical switching loss model for a SiC MOSFET and Schottky diode half-bridge for a wide operating range is proposed in this paper, which is based on nonlinear differential circuit equations including parasitics. In the model, nonlinear device characteristics are used, including the dynamic gatedrain capacitance and the transfer characteristics measured under real switching conditions. With the proposed model, the accuracy improvement by using measured characteristics instead of device data sheet information is analyzed. In addition, the impact of making different common assumptions/simplifications on the accuracy of switching loss models is evaluated.

Verification and Application of an Analytical Switching Loss Model for a SiC MOSFET and Schottky Diode Half-Bridge

“…In order to draw a more general conclusion, a comprehensive error analysis for more assumptions, operating points, and DUTs is required. Therefore, this paper comprehensively verifies the accuracy of the benchmark model presented in [3] in a wide operating range for DUTs from different manufacturers under different gate drive circuit conditions. Also, the possible accuracy improvement by using measured device characteristics instead of data sheet information is investigated in detail.…”

“…The computational effort of the analytical switching loss models presented in [2]- [12] is simplified by using different assumptions/simplifications, which can be classified into 3 groups based on the analysis given in [3]. The first group approximates the nonlinear device characteristics (e.g.…”

“…In order to investigate the impact of different assumptions, [3] proposes a comprehensive and accurate analytical switching loss model for a SiC MOSFET and Schottky diode half-bridge with a wide operating range as a benchmark. The benchmark model is based on nonlinear differential circuit equations that are derived including parasitics with few assumptions/simplifications.…”

“…1 depicts the considered equivalent circuit for a hard-switched SiC MOSFET and a SiC Schottky diode half-bridge. In addition, the accuracy improvement by using measured device characteristics instead of data sheet information is investigated in [3], using 3 groups of device parameters including data sheet values (DSV), power device analyzer measurement values (PDAMV), and full measurement values (FMV). Compared to the PDA measurement, the full measurement also includes the dynamic gate-drain capacitance C gd,dy based on gate charge measurements, the I ds -V gs transfer characteristics during high voltage, high current (HVHI) switching transients, and the measured package parasitic inductances.…”

“…Compared to the PDA measurement, the full measurement also includes the dynamic gate-drain capacitance C gd,dy based on gate charge measurements, the I ds -V gs transfer characteristics during high voltage, high current (HVHI) switching transients, and the measured package parasitic inductances. In [3], it is preliminarily concluded, that the device parameters characterized by static measurements (data sheet information and PDA measurements) are not accurate enough for precisely calculating the switching losses. Instead, C gd,dy and the I ds -V gs transfer characteristics during HVHI switching transients need to be measured and used.…”