Active clamping method for SiC MOSFET high power modules : Benefits and Limits

Titelangaben

Maier, Robert ; Bakran, Mark-M.:
Active clamping method for SiC MOSFET high power modules : Benefits and Limits.
In: 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe). - Piscataway, NJ : IEEE , 2020 . - S. 1-10
ISBN 978-9-0758-1536-8
DOI: https://doi.org/10.23919/EPE20ECCEEurope43536.2020.9215899

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Abstract

For high power applications, the SiC MOSFET switching speed is limited by the inductive overvoltage
due to the high product of stray inductance and switched current [1]. The active clamping method properly
designed for high power applications, allows the increase of the du=dt during the turn-off process
without exceeding the MOSFET maximum blocking voltage. This paper investigates the active clamping
method via scaled single chip measurements. This scheme includes scaling accordingly the commutation
circuit stray inductance and the active clamping path, emulating the full module switching behavior with
single chip measurements. In comparison to simple gate resistor controlled switching, the active clamping
method allows a higher voltage gradient during the switching process while effectively limiting the
overvoltage. Results show, that losses could be reduced in the range by 30% (for high current) and up
to 70% (for low current). However, special focus has to be placed on the thermal design of the active
clamping circuit. The temperature dependent breakthrough voltage of the transient voltage suppression
diodes has to be considered for the correct implementation of the active clamping circuit.