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GATE 2020 EE – Question 30

Power Electronics · Static V-I characteristics and firing/gating circuits for Thyristor, MOSFET, IGBT · 1 mark · Numerical answer

A double pulse measurement for an inductively loaded circuit controlled by the IGBT switch is carried out to evaluate the reverse recovery characteristics of the diode, D, represented approximately as a piecewise linear plot of current vs time at diode turn-off. $L_{par}$ is a parasitic inductance due to the wiring of the circuit, and is in series with the diode. The point on the plot (indicate your choice by entering 1, 2, 3 or 4) at which the IGBT experiences the highest current stress is ________.

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Correct answer: 3

Explanation

During the diode's reverse recovery the IGBT carries the load current plus the reverse recovery current of the diode. The current through the IGBT is therefore largest when the diode's reverse current is at its peak, which is point 3 on the plot.