Do you have experience with SPICE simulation of IGBT switching, how realistic ? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 09, 2020, 06:01:15 am
content: Hi folks,Do you have experience with simulating IGBTs switching behavior and losses ? I know it will be hugely affected by provided models. I want to use infineons devices.I know they tell simulation dont replace measuring a prototype, but are results at least reasonable close to reality? Like +-10-20% ?

author: fourtytwo42
author_rank: Super Contributor
timestamp: April 15, 2020, 06:09:53 pm
content: Surprised nobody else answered you however simulations especially switching depend on how well you simulate all the other circuit elements, especially the driver, the load if its inductive, any current the diode is going to handle and any potential avalanche power. I have done plenty of sims and actuals with mosfets, less so with igbt's and I would not say the sims have been an order of magnitude out but as I say it depends how much effort you put into modelling. Tuning at the prototype is fairly easy unless you make a bad mistake (heatsink to small, bad layout resulting in excessive ringing etc).

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 17, 2020, 08:37:24 am
content: I know modeling can be tricky. But basically from layout data you can get all traces stray inductance, what is main issueTraces coupling will be missing but it is more issue on small signal control loopsThen is only question how models represent behavior of active devices

author: fourtytwo42
author_rank: Super Contributor
timestamp: April 25, 2020, 10:34:36 am
content: To answer that you would have to inspect the model for the accuracy of the parameters that concern you. Most semi manufacturers mosfet/igbt models I have encountered are good enough for normal purposes however I have encountered some rubbish models on the general web through searching for component xyz so it just the same as the old saying "buyer beware".

author: Yansi
author_rank: Super Contributor
timestamp: April 25, 2020, 10:37:02 am
content: Why do you need to model it? All you need is the Eon Eoff energy from the datasheet and the Vcesat(Ic) curves.

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 25, 2020, 05:17:54 pm
content: Quote from: Yansi on April 25, 2020, 10:37:02 amEon Eoff are very layout dependent (stray inductance)and Eon are for specific diode, yes it can be calculated to other diode by Crr to some degreeespecially at fast IGBTs with tr 7ns and tf 21ns at Ic 25Aat this speed other circuit components have huge impact

author: Yansi
author_rank: Super Contributor
timestamp: April 25, 2020, 09:44:58 pm
content: I think with IGBT (which are rather on the slow side of switching). parasitic ESL and C of the layout is hardly of concern. But when talking MOSFET/SiC, that would be quite a different matter.But a good point with the diode of course. Hence you should prefer IGBTs with integrated diodes: Both you get the correct Eon (that includes the recovery charge from the opposing diode) and you get much better chances at the layout.

author: Miyuki
author_rank: Frequent Contributor
timestamp: April 26, 2020, 07:45:57 am
content: Yes with slow IGBT it is not a concern, but today there are many high speed IGBTs even for high current (higher tens of Amps), where they have better performance than 600V mosfets even at 50-100kHz rangeAnd as they are much cheaper for same current rating it is interesting alternativeBut this frequency range start to be tricky with layoutAlso there are many typologies what rely on external diode, for example recovery of diode on second side of converter transfer to loss in primary side transistors