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I read that one of the major power losses of an IGBT circuit is its switching losses.In order to overcome it, soft-switching is used. The book gave an example with the circuit diagram:

This is know as "soft switching". The voltage or current applied to the switching circuit can be made approximately zero by using the resonance created by the LC resonant circuit and the anti-parallel diode across the collector to emitter of the IGBT. Gate switch control from the MCU has the voltage of the switching circuit VCE set to zero right before the circuit is turned on (ZVS) and having the IGBT current fl ow close to zero (ZCS) right before turning it off.

enter image description here

I understood that how ZVS and ZCS work in order to avoid power losses but I cannot understand how the given circuit above uses the LC resonant circuit to delay(?) the current before turning on the IGBT or delay(?) the voltage before turning off IGBT. It will also help me if you can give other circuit example(that is not too complex) having soft-switching. Circuit above is a resonant inverter with induction cooking

hontou_
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  • Have you tried to simulate it? – winny Jun 08 '20 at 08:22
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    that's a frying pan? – Jasen Слава Україні Jun 08 '20 at 09:18
  • I did not tried to simulate it yet and yes thats a frying pan, I edited that now – hontou_ Jun 08 '20 at 10:06
  • Simulation should be your first step before asking. – winny Jun 08 '20 at 10:10
  • https://toshiba.semicon-storage.com/ap-en/semiconductor/knowledge/faq/mosfet_igbt/igbt-013.html – G36 Jun 08 '20 at 16:02
  • @G36, why does when current starts increasing, the Vce is still zero? I get that the current will drop approximately zero or 0.7 at the diode D5 before the current starts increasing. But I don't get why after that drop in diode of IGBT, the Vce does not rise... I mean Vce should only reach approx zero when current reaches the max where all drop will be at the Inductor.... What am I missing? – hontou_ Jun 10 '20 at 13:58
  • The Vce voltage is zero or close to zero because at this time the IGBT is fully ON (saturated). Thus, all the supply voltage is present across the heating coil. – G36 Jun 10 '20 at 19:27

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