LTSpice SCR simulation help

[anishkgt]

Hi All,

I am trying to simulate an scr working for determining snubber values. I just can get the parameters correct for it to work.

Would appreciate if anybody could help me resolve this error.

[Ian.M]

You need a LTspice model for the thyristor, and to include it with a .lib statement.

[anishkgt]

I added the symbol from LTSpice. Wouldn't the lib also present there ?

Could you please direct me to any resources that i could follow to get this done.

[Ian.M]

Didn't you read the description when you selected the SCR symbol in the component browser?
It says: "Generic SCR symbol for use with a model that you supply."

Search the web for a model for the SCR you want to use, which will be a .sub or .lib file (possibly zipped).  .lib files can contain multiple models.   A model in LTspice format is strongly preferred, as there are some syntax differences for behavioural sources that can cause problems if you attempt to use models intended for PSPICE or other SPICEs.  However many PSPICE models are fully LTspice compatible.   Download it and if its zipped extract it into the same folder as your simulation.  Add a .lib or .inc statement to the schematic, naming the file containing the model.  Use a .inc statement if its a .sub file or .lib if its a .lib file.   Make sure the 'Value' field of the SCR symbol you have placed EXACTLY matches the name of the model inside the .lib or .sub file.

[anishkgt]

Sorry am just beginning to learn to work with LTSpice.


Still can get that error fixed. I did see it was generic but not sure how to go about it. I did not find any SCR models but just a lib file from this forum, added that file to where the schematic is saved. Is there anything that i should consider as running the simulation gives an error.

How do i know if the the model matches a symbol ?

here is my LTSpice net list
* C:\Users\georget\Documents\LTspiceXVII\SCR_Snubber.asc
XU1 N001 N003 N007 EC103D1
XU2 N007 N005 N001 EC103D1
C1 N006 N007 0.1µf V=400
XU3 N002 0 N003 N004 NC_01 MOC205 Igain=.724m
D1 N001 N003 D
D2 N007 N005 D
R1 N005 N004 360
R2 N001 N003 360
R3 N001 N006 39
R4 N005 N007 360
V1 N001 0 SINE(0 240 60 0 0 0 5)
L1 N007 0 100µ Ipk=5
L2 N009 N008 2.4µ Ipk=2000
V2 N002 0 PULSE(5 5 20 1 3 3 1 0)
R5 N008 N009 0.09 tol=1 pwr=200
.model D D
.lib C:\Users\georget\Documents\LTspiceXVII\lib\cmp\standard.dio
K L1 L2 1
.tran 10
.lib MOC205.sub
.backanno
.end

[Ian.M]

Try the attached sim.  I've renamed the SCR .lib for convenience.
Problems your original had:

• No .lib statement to provide the SCR model
• U1 and U2 had an extra parameter '20A' that was invalid
• No path to ground from the transformr secondary

[anishkgt]

Thanks that worked like a charm.