Comparative Study of IGBT and SiC MOSFET Three-Phase Inverter: Impact of Parasitic Capacitance on the Output Voltage Distortion

Abstract

This study investigates the nonlinearities in three-phase inverters for SiC-based systems and compares their performance to IGBT-based systems. An analytical model of inverter voltage distortion is developed, which accounts not only for dead time (td), switching delay time, switching frequency (fs), and voltage drops of power devices, but also for output parasitic capacitance (Cout). Experimental tests validate the model, which provides a more accurate estimate of the inverter’s output phase voltage distortion. The power device characteristics are obtained from datasheets, while Cout is determined through experimentation. Three-phase inverters with varying switching frequencies, fundamental frequencies, and dead-time values are used in simulations and experiments to determine the influence of nonlinearity on phase voltage deviation and current distortion. The results show that, due to SiC devices’ faster switching time, the phase voltage deviation and phase current distortion are lower in SiC-based inverters than in IGBT-based ones for high-frequency applications, as the dead time can be reduced.

Influence of High-Frequency Operation on the Efficiency of a PMSM Drive with SiC-MOSFET Inverter

“…Figure 2 illustrates the different voltage drops in the output voltage. Based on the results presented in [16,17], this voltage drop increases as the switching frequency increases. Therefore, at higher speeds for which the motor requires more voltage, this may pose a problem.…”

“…Therefore, at higher speeds for which the motor requires more voltage, this may pose a problem. For further details on these effects, please refer to [16,17], which provides a comprehensive explanation.…”

“…The authors of [17] also explored the impact of varying the PWM frequency and dead time on the total harmonic distortion (THD) within the voltage and current waveforms of inverters constructed using IGBT, Fast IGBT, and SiC-MOSFET.…”

“…However, the ability to decrease the dead time, a characteristic associated with SiC-MOSFET components, notably enhances THD performance. Notably, setting the dead time to 0.5 µs maintains the THD at 95% across different PWM frequencies [17].…”

“…The effects of high switching frequencies on the performance of power electronics converters have been extensively studied in various papers across different applications. In [16,17], the nonlinearities in SiC-based three-phase inverters and IGBT-based inverters are studied and compared by considering factors such as dead time, switching delay time, switching frequency, and output parasitic capacitance. The authors of [18] investigated the impact of dead time on SiC-BJT and SiC-MOSFET on converter losses in a high-frequency resonant converter.…”