Lecture 15: Switching Losses and Snubbers

MIT 6.622 Power Electronics, Spring 2023
Instructor: Xin Zan
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In this lecture, we do a back of the envelope calculation on semiconductor losses, including conduction losses and switching losses. We also explore the use of snubbers to modify the switching transitions to reduce noise, protect the semiconductor devices, and reduce internal device dissipation.
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[@bendon4604]

during the demo of Switching Loss, the Math function was multiplying Ch1 by itself. So that did not show switching loss but rather Current^2. That's why the waveform was not triangular like the theory suggested. Otherwise, great lecture!

[@gungagalunga9040]

You look different this week Doc

[@brucebuckeye]

Excellent! Thank you

[@arishrager]

Excellent tutorial ! Thank you

[@johnwilson839]

on the full bridge forward converter how do you ensure that the positive V seconds exactly equals the negative Volt Seconds. for instance what if the switches are slightly mismatched? will you build up flux?

[@railspony]

It shouldn't build up because 1) any offset will simply drive the circuit slightly harder and escape 2) you're pausing at 0V giving it an escape path and 3) you're driving the magnetics both positive and negative in each cycle which should reset it. In most practical devices, even if you perfectly match the switches you'll still have between 5 and 30 ns difference in the on/off duty cycles of the switch drivers, so you'll only be closely matched, never exactly matched.

[@rafalklepinski7372]

Just got my textbook for this course today, so exciting :)

[@walterbaldemor2128]

Thank you sir for explaining the ideal diode