Twelve-pulse diode set with transformers
.opt reltol=0.01 itl5=0 itl4=100
.tran 100us 0.05s 0s 50us uic
va 51 0 sin(0 170 60 0)
vb 52 0 sin(0 170 60 0 0 120)
vc 53 0 sin(0 170 60 0 0 240)
ra 51 101 0.001
rb 52 102 0.001
rc 53 103 0.001
la1 101 0 1
lb1 102 0 1
lc1 103 0 1
la2 201 0 1
lb2 202 0 1
lc2 203 0 1
ka la1 la2 0.999999
kb lb1 lb2 0.999999
kc lc1 lc2 0.999999
la3 301 311 3
rad 311 302 0.001
lb3 302 312 3
rbd 312 303 0.001
lc3 303 313 3
rcd 313 301 0.001
ka2 la1 la3 0.99999
kb2 lb1 lb3 0.99999
kc2 lc1 lc3 0.99999
ka3 la2 la3 0.99999
kb3 lb2 lb3 0.99999
kc3 lc2 lc3 0.99999
ra2 201 251 0.01
rb2 202 252 0.01
rc2 203 253 0.01
ra3 301 351 0.01
rb3 302 352 0.01
rc3 303 353 0.01
da2 251 1 dio
db2 252 1 dio 
dc2 253 1 dio
da3 351 1 dio
db3 352 1 dio
dc3 353 1 dio
da4 2 251 dio
db4 2 252 dio
dc4 2 253 dio
da5 2 351 dio
db5 2 352 dio
dc5 2 353 dio
lout 1 3 150mH ic=34A
rout 3 2 8.400
cout 3 2 500uF ic=286.4V
.model dio D(Is=10p Rs=0.01)
.probe
.end