Analysis of Overvoltage Across Blanking Capacitor Due to Junction Capacitance of Sensing Diode in Desat Protection of SiC MOSFET

Prasad, KNV and Ahmad, SS and Narayanan, G (2024) Analysis of Overvoltage Across Blanking Capacitor Due to Junction Capacitance of Sensing Diode in Desat Protection of SiC MOSFET. In: 2024 IEEE International Communications Energy Conference, INTELEC 2024, 4 August 2024 - 7 August 2024, Bengaluru.

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Abstract

Wide-band-gap devices exhibit rapid switching capabilities, enhancing conversion efficiency and reducing converter size. However, their low short circuit withstand time (SCWT) capacity necessitates swift and precise fault detection and protection mechanisms. The reduction in fault detection time in desaturation (Desat) based protection requires minimising blanking capacitance. When the blanking capacitance is comparable to the sensing diode junction capacitance, the reverse recovery current of the sensing diode and oscillations across the device lead to overvoltage across the blanking capacitor during device turn-off and discontinuous current mode (DCM) operation, respectively, which leads to spurious fault detection. Based on variable junction capacitance of sensing diode, this paper presents an analytical method to estimate overvoltage across blanking capacitor during turn-off. This paper also derives a transfer function relating the device voltage oscillations with blanking capacitor voltage oscillations during DCM, which shows the impact of reduced blanking capacitance on overvoltage. Simulations and experiments validate the accuracy of the analytical methods proposed. Additionally, a recently proposed voltage clamping method is implemented to clamp such overvoltages, and experimental results on an 800-V(dc), 50-A(rms), and 50-kHz asymmetric H-bridge (AHB) converter are presented. © 2024 IEEE.

Item Type:	Conference Paper
Publication:	INTELEC, International Telecommunications Energy Conference (Proceedings)
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to the publisher.
Keywords:	Circuit oscillations; Clamping devices; Gallium compounds; Heterojunctions; MOSFET devices; Organoclay; Overvoltage protection; System-on-chip, Analytical method; Desaturation; Discontinuous current mode; Faults detection; Junction capacitances; Over-voltages; SiC MOSFETs; Turn offs; Voltage oscillation; Wide band gap devices, Capacitor bank
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	16 Nov 2024 13:46
Last Modified:	16 Nov 2024 13:46
URI:	http://eprints.iisc.ac.in/id/eprint/86725

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