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Some update to SOA for a diode: 

Limit output to four digits
Add power and temperature limits.
Derating with self-heating, or with fixed temperature,
or no derating at all, selectable by setting model parameters.
Example file: SOA plotted as frame, with diode current.
pre-master-46
Holger Vogt 5 years ago
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33571877dc
2 changed files with 177 additions and 19 deletions
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  1. 117
      examples/various/diode-soa-sh.cir
  2. 79
      src/spicelib/devices/dio/diosoachk.c

117
examples/various/diode-soa-sh.cir
View File

@ -0,0 +1,117 @@
SOA test for generic diode, including self-heating
* forward direction
* ngspice-35
*.temp 200
vtamb tamb 0 27
v1 1 0 0.7
R1 1 0 100 ; just a parallel resistor
D1 1 0 tj dmod thermal
Rtj tj tamb 100 ; the thermal resistance junction to ambient
* diode model parameters include all SOA parameters
.model dmod d (rs=200m bv=21 rth0=1e6 tnom=25 fv_max=1.5 bv_max=20 id_max=1.5 pd_max=1 te_max=175)
.option warn=1 maxwarns=2
.control
save @d1[id] all
*dc v1 3 -22.5 -0.5
dc v1 0.02 2 0.02
*display
set xbrushwidth=3
* get data from diode model
let pdmax = @dmod[pd_max]
let idmax = @dmod[id_max]
let vmax = @dmod[fv_max]
let tmax = @dmod[te_max]
let tnom = @dmod[tnom]
let iid = @d1[id]
let ilen = length(iid)
let soa = unitvec(ilen) * idmax
* the current power dissipation in the diode
let pd=@d1[id]*v(1) + 1p ; 1p for log scale, avoid 0
* plot the static SOA diagram
* no self heating
let i = 0
while i < ilen
* power limit
let pp = soa[i] * v(1)[i]
if pp > pdmax
let soa[i] = soa[i] * pdmax / pp
end
* voltage limit
if v(1)[i] > vmax
let soa[i] = 1p
end
* temperature limit
let tcur = pp * @Rtj[r] + v(tamb)
if tcur[i] > tmax
let soa[i] = 1p
end
let i = i + 1
end
settype current iid soa
plot iid soa loglog ylimit 10m 10 xlimit 0.1 1 title 'Diode SOA (safe operating area, no self-heating)' ylabel 'Diode current' xlabel 'Diode forward voltage'
unlet pdmax
let pdmax = @dmod[pd_max] - (v(tj) - tnom) / @Rtj[r]
let tdio = v(tj)
echo
*echo pdmax $&pdmax
*echo temp $&tdio
*echo tnom $&tnom
echo
let plen = length(pdmax)
let i = 0
while i < plen
if pdmax[i] < 0
let pdmax[i] = 1p
end
let i = i + 1
end
* plot the static SOA diagram
* now with self heating
let i = 0
while i < ilen
* power limit
let pp = soa[i] * v(1)[i]
if pp > pdmax[i]
let soa[i] = soa[i] * pdmax[i] / pp
end
* voltage limit
if v(1)[i] > vmax
let soa[i] = 1p
end
* temperature limit
let tcur = pp * @Rtj[r] + v(tamb)
if tcur[i] > tmax
let soa[i] = 1p
end
let i = i + 1
end
settype current iid soa
plot iid soa loglog ylimit 10m 10 xlimit 0.1 1 title 'Diode SOA (safe operating area, including self-heating)' ylabel 'Diode current' xlabel 'Diode forward voltage'
*settype power pd pdmax
*plot pd pdmax loglog ylimit 1m 10 xlimit 0.1 1
*settype temperature tj
*plot tj
*plot pd vs tj pdmax vs tj
.endc
.end

79
src/spicelib/devices/dio/diosoachk.c
View File

@ -20,6 +20,7 @@ DIOsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
double vd; /* current diode voltage */
double id; /* current diode current */
double pd; /* current diode power */
double pd_max; /* maximum diode power */
double te; /* current diode temperature */
int maxwarns;
static int warns_fv = 0, warns_bv = 0, warns_id = 0, warns_pd = 0, warns_te = 0;
@ -45,7 +46,7 @@ DIOsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
if (vd > model->DIOfv_max)
if (warns_fv < maxwarns) {
soa_printf(ckt, (GENinstance*) here,
"Vd=%g V has exceeded Fv_max=%g V\n",
"Vd=%.4g V has exceeded Fv_max=%.4g V\n",
vd, model->DIOfv_max);
warns_fv++;
}
@ -53,7 +54,7 @@ DIOsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
if (-vd > model->DIObv_max)
if (warns_bv < maxwarns) {
soa_printf(ckt, (GENinstance*) here,
"Vd=%g V has exceeded Bv_max=%g V\n",
"Vd=%.4g V has exceeded Bv_max=%.4g V\n",
vd, model->DIObv_max);
warns_bv++;
}
@ -62,7 +63,7 @@ DIOsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
if (id > fabs(model->DIOid_max))
if (warns_id < maxwarns) {
soa_printf(ckt, (GENinstance*) here,
"Id=%g A at Vd=%g V has exceeded Id_max=%g A\n",
"Id=%.4g A at Vd=%.4g V has exceeded Id_max=%.4g A\n",
id, vd, model->DIOid_max);
warns_id++;
}
@ -72,25 +73,65 @@ DIOsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
*(ckt->CKTstate0 + here->DIOvoltage) +
*(ckt->CKTstate0 + here->DIOcurrent) *
*(ckt->CKTstate0 + here->DIOcurrent) / here->DIOtConductance);
if (pd > fabs(model->DIOpd_max))
if (warns_pd < maxwarns) {
soa_printf(ckt, (GENinstance*) here,
"Pd=%g W at Vd=%g V has exceeded Pd_max=%g W\n",
pd, vd, model->DIOpd_max);
warns_pd++;
}
te = here->DIOtemp - CONSTCtoK;
if (te > model->DIOte_max)
if (warns_te < maxwarns) {
soa_printf(ckt, (GENinstance*) here,
"Te=%g C at Vd=%g V has exceeded te_max=%g C\n",
te, vd, model->DIOte_max);
warns_te++;
/* calculate max power including derating:
up to tnom the derating is zero,
at maximum temp allowed the derating is 100%.
Device temperature by self-heating or given externally. */
if (here->DIOthermal && model->DIOrth0Given && model->DIOpd_maxGiven
&& model->DIOte_maxGiven && model->DIOnomTempGiven) {
te = ckt->CKTrhsOld[here->DIOtempNode];
if (te < model->DIOnomTemp)
pd_max = model->DIOpd_max;
else {
pd_max = model->DIOpd_max - (te - model->DIOnomTemp) / model->DIOrth0;
pd_max = (pd_max > 0) ? pd_max : 0.;
}
if (pd > pd_max)
if (warns_pd < maxwarns) {
soa_printf(ckt, (GENinstance*)here,
"Pd=%.4g W at Vd=%.4g V and Te=%.4g C has exceeded Pd_max=%.4g W\n",
pd, vd, te, pd_max);
warns_pd++;
}
if (te > model->DIOte_max)
if (warns_te < maxwarns) {
soa_printf(ckt, (GENinstance*)here,
"Te=%.4g C at Vd=%.4g V has exceeded te_max=%.4g C\n",
te, vd, model->DIOte_max);
warns_te++;
}
}
/* derating without self-heating, external temp given */
else if (!here->DIOthermal && here->DIOtempGiven && model->DIOrth0Given && model->DIOpd_maxGiven
&& model->DIOte_maxGiven && model->DIOnomTempGiven) {
if (here->DIOtemp < model->DIOnomTemp)
pd_max = model->DIOpd_max;
else {
pd_max = model->DIOpd_max - (here->DIOtemp - model->DIOnomTemp) / model->DIOrth0;
pd_max = (pd_max > 0) ? pd_max : 0.;
}
if (pd > pd_max)
if (warns_pd < maxwarns) {
soa_printf(ckt, (GENinstance*)here,
"Pd=%.4g W at Vd=%.4g V and Te=%.4g C has exceeded Pd_max=%.4g W\n",
pd, vd, here->DIOtemp - CONSTCtoK, pd_max);
warns_pd++;
}
}
/* no derating */
else {
pd_max = model->DIOpd_max;
if (pd > pd_max)
if (warns_pd < maxwarns) {
soa_printf(ckt, (GENinstance*)here,
"Pd=%.4g W at Vd=%.4g V has exceeded Pd_max=%.4g W\n",
pd, vd, pd_max);
warns_pd++;
}
}
}
}
return OK;

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