For power electronics circuit simulation, modeling a semi-conductor switch correctly is very important. The two semi-conductor switches used in the examples I have given on this page are diode and SCR. The diode model used is as follows:
.MODEL DNAME D(IS=1E-10 N=1 BV=1200 IBV=10E-3 VJ=0.7)
This defines the diode being used to have saturation current (IS) equal to 0.1 nA, Emission coefficient (N) equal to 1, reverse breakdown voltage (BV) equal to 1200 V, reverse breakdown current (IBV) equal to 10 mA and the juction potential (VJ) equal to 0.7 V.
The SCR model used was obtained from the Third year Power Laboratory Notes, University of Wollongong. It is defined as a subcircuit scr.cir. It is given below.
.subckt scr 1 2 3 2
s1 1 5 6 2 smod
rg 3 4 50
vx 4 2 dc 0V
vy 5 7 dc 0V
dt 7 2 dmod
rt 6 2 1
ct 6 2 10uf
f1 2 6 poly(2) vx vy 0 50 11
.model smod vswitch(ron=0.0105 roff=10e+5 von=0.5V voff=0V)
.model dmod d(is=2.2e-15 bv=1200V tt=0 cjo=0)