Benefit of Silicon Carbide vs Silicon diode - Page 1
Forum section: electronics / beginners

author: anandrmp
author_rank: Newbie
timestamp: October 31, 2014, 07:27:18 pm
content: Hi Guys,I have a question:Working on a project to illustrate the benefits of 3c-sic (cubic silicon carbide) diode vs that of a silicon diodeI first selected a rectifier circuit with a silicon diode.I then tried to make a second circuit/or a switchable circuit substituting the silicon carbide diode in the place of the silicon diode.I would then have to run comparative tests to illustrate the benefits of the Silicon carbide diode vs the silicon diode .I have constructed the circuit with the silicon diode. I am having trouble with verifying if i have properly imported the cubic Silicon carbide diode into the circuit (how to test that) and which tests to run (and how to do them) to illustrate the benefits of using a silicon carbide diode.I have used the following:I have used a comparable diode so instead of the 600 volt silicon diode (1N5406RL) i used a 600 volt silicon carbide diode (STPSC406B-TR). Not sure if it is a 3C-Siliconcarbide diode or just a Silicon Carbide Diode. If not, i need to find a comparable 3C-Sic model.I used Ltspice to simulate.Datasheet silicon carbide diode:http://www.st.com/web/en/resource/technical/document/datasheet/CD00249259.pdfSpice files to import silicon carbide diode into ltspice:http://www.st.com/web/en/catalog/sense_power/FM64/SC489/PF251714?s_searchtype=keyword#I have attached the silicon diode model, the silicon carbide diode model, the diode test circuit and the rectifier model.Could you please help me with these questions? Thanks!!

author: Marco
author_rank: Super Contributor
timestamp: October 31, 2014, 09:08:15 pm
content: AFAICS they aren't even commercially available ... your professor might be able to get one fromAnvilwith a little begging.The advantage of SiC Schottky diodes is mostly that they are Schottky diodes. Power Factor correction is probably the most appropriate circuit to show the advantages of SiC Schottky diodes.

author: anandrmp
author_rank: Newbie
timestamp: October 31, 2014, 09:50:32 pm
content: I have to illustrate the benefits via software simulation, not physical components (if that´s what you mean). Are comparable 3c-Sic models available at Anvil?You said that power factor correction would be the most appropriate circuit to show the advantages. Wouldn´t a rectifier circuit like the one i implemented, on its own, also show the benefits of using the silicon carbide diode?

author: free_electron
author_rank: Super Contributor
timestamp: October 31, 2014, 10:24:29 pm
content: Quote from: anandrmp on October 31, 2014, 09:50:32 pmoh this is theoretical ? in theory everything works. so there ya go. proven.

author: anandrmp
author_rank: Newbie
timestamp: October 31, 2014, 10:39:13 pm
content: I think i misunderstood..what i mean is that i indeed need to use the spice models of the physical components, but i do not have to build the physical circuit itself. I am using Ltspice for comparing.

author: Marco
author_rank: Super Contributor
timestamp: October 31, 2014, 11:20:14 pm
content: Quote from: anandrmp on October 31, 2014, 09:50:32 pmShrug, try asking them (although again, I recommend your professor doing it).QuoteReverse recovery losses aren't very impressive at 50/60 Hz sine wave rectification, PFC works with comparatively fast switching signals stressing the diodes far more. (I'm assuming you want to show the advantages at ambient temperatures.)PS. I don't really see the value in any of this ... it's just so needlessly specific. You obviously don't have the knowledge to quickly gain an understanding of why 3C-SiC might be superior to other forms of SiC diodes (and neither do I). Understanding why a high voltage Schottky diode can be superior in a circuit is straightforward enough and simulations might be a good way of illustrating the advantages, but you can just use the models for commercial SiC diodes for that.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 31, 2014, 11:37:48 pm
content: 1N5406? Gee, at least make it a little interesting. If you look inside the model, you'll see the line "TT=3u" or something near there (as in, 3 microseconds), which means it doesn't stop conducting until about 3 microseconds after current reverses (this is reverse recovery; called Transit Time in the SPICE model). Schottky diodes (of any type, whether SiC or not) do not exhibit this effect (though their models often use a small TT to simulate the higher capacitance characteristic of the diode).SPICE simulation of forward recovery (it isn't modeled!) and reverse recovery (very meh) is notoriously poor, so don't expect great (or even necessarily representative) results.Tim

author: anandrmp
author_rank: Newbie
timestamp: November 01, 2014, 12:00:53 pm
content: Thank you all for your advice, it was very helpful in getting me on the right course with the project!!!

author: nuno
author_rank: Frequent Contributor
timestamp: November 01, 2014, 04:34:37 pm
content: Schottky s are bad at leakage, so maybe the sic is better in that spec.

author: anandrmp
author_rank: Newbie
timestamp: November 01, 2014, 05:22:41 pm
content: As a beginner, I am still working on the basics. I understand that fast switching signals would better illustrate the switching benefits of the SIC. If i just used the rectifier (to at least show some benefit of the SIC in the current circuit) wouldn´t a possible benefit be, the ability of the circuit to rectify larger currents? I think i then would also need to modify the original (using just silicon diodes) values of the components in the circuit?Trying to test if i imported the silicon carbide diode correctly into the test circuit. I am using the specified silicon carbide diode. When i try to test it I don´t get the VI curve i expect from the datasheet, probably doing something wrong. Any idea would help