While my sim is running, I can do all sorts of things. Grocery shop,
prowl the web, take a nap.

https://xkcd.com/303/

Same idea. My alternator simulator simulation (!) takes about 25
minutes to rev up, running 10 or so PPM of real time. It's nicely
settled in about an hour.

John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>
>
> While my sim is running, I can do all sorts of things. Grocery shop,
> prowl the web, take a nap.
>
> https://xkcd.com/303/
>
> Same idea. My alternator simulator simulation (!) takes about 25
> minutes to rev up, running 10 or so PPM of real time. It's nicely
> settled in about an hour.
>
>

It’s probably pretty linear, so you could solve the DE by hand. Then you’d
have more info than a stack of sims.

But then your fencing would suffer. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics,
Electro-optics, Photonics, Analog Electronics

On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>
>>
>> While my sim is running, I can do all sorts of things. Grocery shop,
>> prowl the web, take a nap.
>>
>> https://xkcd.com/303/
>>
>> Same idea. My alternator simulator simulation (!) takes about 25
>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> settled in about an hour.
>>
>>
>
>It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>have more info than a stack of sims.

It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
current limiters, 3-phase common-mode chokes, ferrite beads, about 50
bypass caps. I'm not smart enough to do that analytically.

The sim includes the FADEC power supply, which rectifies the 3-phase
alternator output and shorts it when the DC voltage gets too high.

What a mess: I have the simlated alternator frequency, some low KHz.
The PWM driver stage at 250 KHz. And the simulated FADEC which PWM
shorts my fake alternator at about 30 KHz, when it feels like.

This represents the load that I'm driving, what I imagine a FADEC
power supply might do. PM alternators don't mind being shorted.

https://www.dropbox.com/scl/fi/lk0p4dj4a9dtlw1b2kh6r/Fadec_Box.jpg?rlkey=1hsxoak5xc32ul3ymdb06oh12&raw=1

It's under 10% of the total sim schematic.

>
>But then your fencing would suffer. ;)

My brain would explode. Spice avoids a lot of hard thinking.

>
>Cheers
>
>Phil Hobbs

On Thursday, August 17, 2023 at 6:47:11 AM UTC-4, John Larkin wrote:
> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
> <pcdhSpamM...@electrooptical.net> wrote:
>
> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
> >>
> >>
> >> While my sim is running, I can do all sorts of things. Grocery shop,
> >> prowl the web, take a nap.
> >>
> >> https://xkcd.com/303/
> >>
> >> Same idea. My alternator simulator simulation (!) takes about 25
> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
> >> settled in about an hour.
> >>
> >>
> >
> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
> >have more info than a stack of sims.
> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
> bypass caps. I'm not smart enough to do that analytically.

Unless all those subelements interact, it's insane to simulate the whole shebang at once.

>
> The sim includes the FADEC power supply, which rectifies the 3-phase
> alternator output and shorts it when the DC voltage gets too high.
>
> What a mess: I have the simlated alternator frequency, some low KHz.
> The PWM driver stage at 250 KHz. And the simulated FADEC which PWM
> shorts my fake alternator at about 30 KHz, when it feels like.
>
> This represents the load that I'm driving, what I imagine a FADEC
> power supply might do. PM alternators don't mind being shorted.
>
> https://www.dropbox.com/scl/fi/lk0p4dj4a9dtlw1b2kh6r/Fadec_Box.jpg?rlkey=1hsxoak5xc32ul3ymdb06oh12&raw=1
>
> It's under 10% of the total sim schematic.
> >
> >But then your fencing would suffer. ;)
> My brain would explode. Spice avoids a lot of hard thinking.
>
>
> >
> >Cheers
> >
> >Phil Hobbs

On a sunny day (Thu, 17 Aug 2023 06:18:11 -0700 (PDT)) it happened Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote in
<6e59a97a-a0a5-4176-a4c8-199e60a5edc6n@googlegroups.com>:

>On Thursday, August 17, 2023 at 6:47:11 AM UTC-4, John Larkin wrote=
>:
>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>> <pcdhSpamM...@electrooptical.net> wrote:
>>
>> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>> >>
>> >>
>> >> While my sim is running, I can do all sorts of things. Grocery shop,=
>
>> >> prowl the web, take a nap.
>> >>
>> >> https://xkcd.com/303/
>> >>
>> >> Same idea. My alternator simulator simulation (!) takes about 25
>> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> >> settled in about an hour.
>> >>
>> >>
>> >
>> >It’s probably pretty linear, so you could solve the DE by hand. =
>Then you’d
>> >have more info than a stack of sims.
>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>> bypass caps. I'm not smart enough to do that analytically.
>
>Unless all those subelements interact, it's insane to simulate the whole sh=
>ebang at once.

Spice has little differences from reality in its models.
The bigger the thing the more those errors will have an effect,
likely increasing exponential.
To the point of chaos theory where one butterfly wing flapping can create glowball worming.

I looked at the circuit diagram (from J.L.) and I think I can see what it is supposed to do.
But its incomplete so ...
It is gonna need a lot of real testing no matter what that spice says.
I am sure John L knows that.

On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>> <pcdhSpamM...@electrooptical.net> wrote:
>>
>> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>> >>
>> >>
>> >> While my sim is running, I can do all sorts of things. Grocery shop,
>> >> prowl the web, take a nap.
>> >>
>> >> https://xkcd.com/303/
>> >>
>> >> Same idea. My alternator simulator simulation (!) takes about 25
>> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> >> settled in about an hour.
>> >>
>> >>
>> >
>> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>> >have more info than a stack of sims.
>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>> bypass caps. I'm not smart enough to do that analytically.
>
>Unless all those subelements interact, it's insane to simulate the whole shebang at once.

Of course they interact!

The 200 watt floating dc/dc conveter is reasonably independent so
that's a separate sim. Ditto my soft-start circuit that ramps up the
raw 48v bus in to the dc/dc.

High school trig was some time ago, so I have a couple of sims to
verify the basic 3-phase math. Spice could eventually destroy all our
math skills; I use it for voltage dividers and RC timing circuits too.

Is there an anlytical way to express delay lines? I think I saw the
delay case once, in a test for PE registration as a Controls Engineer.

On Thu, 17 Aug 2023 14:40:07 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

>On a sunny day (Thu, 17 Aug 2023 06:18:11 -0700 (PDT)) it happened Fred Bloggs
><bloggs.fredbloggs.fred@gmail.com> wrote in
><6e59a97a-a0a5-4176-a4c8-199e60a5edc6n@googlegroups.com>:
>
>>On Thursday, August 17, 2023 at 6:47:11 AM UTC-4, John Larkin wrote=
>>:
>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>
>>> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>> >>
>>> >>
>>> >> While my sim is running, I can do all sorts of things. Grocery shop,=
>>
>>> >> prowl the web, take a nap.
>>> >>
>>> >> https://xkcd.com/303/
>>> >>
>>> >> Same idea. My alternator simulator simulation (!) takes about 25
>>> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>> >> settled in about an hour.
>>> >>
>>> >>
>>> >
>>> >It’s probably pretty linear, so you could solve the DE by hand. =
>>Then you’d
>>> >have more info than a stack of sims.
>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>> bypass caps. I'm not smart enough to do that analytically.
>>
>>Unless all those subelements interact, it's insane to simulate the whole sh=
>>ebang at once.
>
>Spice has little differences from reality in its models.
>The bigger the thing the more those errors will have an effect,
>likely increasing exponential.
>To the point of chaos theory where one butterfly wing flapping can create glowball worming.
>
>I looked at the circuit diagram (from J.L.) and I think I can see what it is supposed to do.
>But its incomplete so ...
>It is gonna need a lot of real testing no matter what that spice says.
>I am sure John L knows that.

We already sell an alternator simulator, a big rackmount thing with a
big isolation transformer per phase. The new one is much smaller, a
single board, and doesn't have room for transformers, so it's three
half-bridges riding on the floating three-phase N node. I trust the
sim as regards the big-picture theory. The older one worked as
simulated, except for some TI class-D amps blowing up, which we
couldn't have simulated.

We'll build the FADEC regulator as a proto board so we can test things
in real life.

John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
> <bloggs.fredbloggs.fred@gmail.com> wrote:
>
>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>
>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>
>>>>>
>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>> prowl the web, take a nap.
>>>>>
>>>>> https://xkcd.com/303/
>>>>>
>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>> settled in about an hour.
>>>>>
>>>>>
>>>>
>>>> It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>>>> have more info than a stack of sims.
>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>> bypass caps. I'm not smart enough to do that analytically.
>>
>> Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>
> Of course they interact!
>
> The 200 watt floating dc/dc conveter is reasonably independent so
> that's a separate sim. Ditto my soft-start circuit that ramps up the
> raw 48v bus in to the dc/dc.
>
> High school trig was some time ago, so I have a couple of sims to
> verify the basic 3-phase math. Spice could eventually destroy all our
> math skills; I use it for voltage dividers and RC timing circuits too.
>
> Is there an anlytical way to express delay lines? I think I saw the
> delay case once, in a test for PE registration as a Controls Engineer.
>
>

H(f) = exp(-j 2 pi f tau)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>
>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>
>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>
>>>>>>
>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>> prowl the web, take a nap.
>>>>>>
>>>>>> https://xkcd.com/303/
>>>>>>
>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>> settled in about an hour.
>>>>>>
>>>>>>
>>>>>
>>>>> It?s probably pretty linear, so you could solve the DE by hand. Then you?d
>>>>> have more info than a stack of sims.
>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>> bypass caps. I'm not smart enough to do that analytically.
>>>
>>> Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>>
>> Of course they interact!
>>
>> The 200 watt floating dc/dc conveter is reasonably independent so
>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>> raw 48v bus in to the dc/dc.
>>
>> High school trig was some time ago, so I have a couple of sims to
>> verify the basic 3-phase math. Spice could eventually destroy all our
>> math skills; I use it for voltage dividers and RC timing circuits too.
>>
>> Is there an anlytical way to express delay lines? I think I saw the
>> delay case once, in a test for PE registration as a Controls Engineer.
>>
>>
>
>H(f) = exp(-j 2 pi f tau)
Yes, but I think he means the Telegrapher's Equations:

..<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>

Joe Gwinn

Joe Gwinn <joegwinn@comcast.net> wrote:
> On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>
>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>
>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>>> prowl the web, take a nap.
>>>>>>>
>>>>>>> https://xkcd.com/303/
>>>>>>>
>>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>>> settled in about an hour.
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> It?s probably pretty linear, so you could solve the DE by hand. Then you?d
>>>>>> have more info than a stack of sims.
>>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>>> bypass caps. I'm not smart enough to do that analytically.
>>>>
>>>> Unless all those subelements interact, it's insane to simulate the
>>>> whole shebang at once.
>>>
>>> Of course they interact!
>>>
>>> The 200 watt floating dc/dc conveter is reasonably independent so
>>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>> raw 48v bus in to the dc/dc.
>>>
>>> High school trig was some time ago, so I have a couple of sims to
>>> verify the basic 3-phase math. Spice could eventually destroy all our
>>> math skills; I use it for voltage dividers and RC timing circuits too.
>>>
>>> Is there an anlytical way to express delay lines? I think I saw the
>>> delay case once, in a test for PE registration as a Controls Engineer.
>>>
>>>
>>
>> H(f) = exp(-j 2 pi f tau)
>
> Yes, but I think he means the Telegrapher's Equations:
>
> .<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>

Maybe. I use the one I gave much more often. It’s dead useful for modeling
temperature controllers—you model the plant as a delay followed by an
integrator.

You then do a bump test, i.e. dump a half-scale current step into the TE
cooler and measure the temperature response.

You can read the model parameters right off the scope trace, or use a micro
and auto tune.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

On 2023-08-17 17:36, Phil Hobbs wrote:
> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>
>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>
>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>
>>>>>>
>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>> prowl the web, take a nap.
>>>>>>
>>>>>> https://xkcd.com/303/
>>>>>>
>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>> settled in about an hour.
>>>>>>
>>>>>>
>>>>>
>>>>> It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>>>>> have more info than a stack of sims.
>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>> bypass caps. I'm not smart enough to do that analytically.
>>>
>>> Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>>
>> Of course they interact!
>>
>> The 200 watt floating dc/dc conveter is reasonably independent so
>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>> raw 48v bus in to the dc/dc.
>>
>> High school trig was some time ago, so I have a couple of sims to
>> verify the basic 3-phase math. Spice could eventually destroy all our
>> math skills; I use it for voltage dividers and RC timing circuits too.
>>
>> Is there an anlytical way to express delay lines? I think I saw the
>> delay case once, in a test for PE registration as a Controls Engineer.
>>
>>
>
> H(f) = exp(-j 2 pi f tau)
>
> Cheers
>
> Phil Hobbs
>

Which says, in the frequency domain, that the phase of the output is
turned backwards in proportion to the delay and to the frequency.

Delays are a nuisance in closed-loop feedback systems.

Jeroen Belleman

On Thu, 17 Aug 2023 16:29:53 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>Joe Gwinn <joegwinn@comcast.net> wrote:
>> On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>
>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>>
>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>
>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>>>> prowl the web, take a nap.
>>>>>>>>
>>>>>>>> https://xkcd.com/303/
>>>>>>>>
>>>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>>>> settled in about an hour.
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> It?s probably pretty linear, so you could solve the DE by hand. Then you?d
>>>>>>> have more info than a stack of sims.
>>>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>>>> bypass caps. I'm not smart enough to do that analytically.
>>>>>
>>>>> Unless all those subelements interact, it's insane to simulate the
>>>>> whole shebang at once.
>>>>
>>>> Of course they interact!
>>>>
>>>> The 200 watt floating dc/dc conveter is reasonably independent so
>>>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>>> raw 48v bus in to the dc/dc.
>>>>
>>>> High school trig was some time ago, so I have a couple of sims to
>>>> verify the basic 3-phase math. Spice could eventually destroy all our
>>>> math skills; I use it for voltage dividers and RC timing circuits too.
>>>>
>>>> Is there an anlytical way to express delay lines? I think I saw the
>>>> delay case once, in a test for PE registration as a Controls Engineer.
>>>>
>>>>
>>>
>>> H(f) = exp(-j 2 pi f tau)
>>
>> Yes, but I think he means the Telegrapher's Equations:
>>
>> .<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>
>
>Maybe. I use the one I gave much more often. It’s dead useful for modeling
>temperature controllers—you model the plant as a delay followed by an
>integrator.
>
>You then do a bump test, i.e. dump a half-scale current step into the TE
>cooler and measure the temperature response.
>
>You can read the model parameters right off the scope trace, or use a micro
>and auto tune.
>
>Cheers
>
>Phil Hobbs

What about startup slewing?

We use Spice to model fairly high-order tremperature controllers and
the small-signal loop response is only part of the concern. A recent
customer wanted an optical modulator to get stable to 0.05c in one
hour from cold start, and that's substantially nonlinear.

The hard part of simming that is modeling diffusion and estimating
heat losses to ambient from various surfaces of the oven box.

On 2023-08-17 13:07, John Larkin wrote:
> On Thu, 17 Aug 2023 16:29:53 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> Joe Gwinn <joegwinn@comcast.net> wrote:
>>> On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>
>>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>>>
>>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John
>>>>>> Larkin wrote:
>>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>>
>>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com>
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> While my sim is running, I can do all sorts of
>>>>>>>>> things. Grocery shop, prowl the web, take a nap.
>>>>>>>>>
>>>>>>>>> https://xkcd.com/303/
>>>>>>>>>
>>>>>>>>> Same idea. My alternator simulator simulation (!)
>>>>>>>>> takes about 25 minutes to rev up, running 10 or so
>>>>>>>>> PPM of real time. It's nicely settled in about an
>>>>>>>>> hour.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> It?s probably pretty linear, so you could solve the DE
>>>>>>>> by hand. Then you?d have more info than a stack of
>>>>>>>> sims.
>>>>>>> It's a mess of PWM modulators, mosfet half-bridges,
>>>>>>> cycle-by-cycle current limiters, 3-phase common-mode
>>>>>>> chokes, ferrite beads, about 50 bypass caps. I'm not
>>>>>>> smart enough to do that analytically.
>>>>>>
>>>>>> Unless all those subelements interact, it's insane to
>>>>>> simulate the whole shebang at once.
>>>>>
>>>>> Of course they interact!
>>>>>
>>>>> The 200 watt floating dc/dc conveter is reasonably
>>>>> independent so that's a separate sim. Ditto my soft-start
>>>>> circuit that ramps up the raw 48v bus in to the dc/dc.
>>>>>
>>>>> High school trig was some time ago, so I have a couple of
>>>>> sims to verify the basic 3-phase math. Spice could eventually
>>>>> destroy all our math skills; I use it for voltage dividers
>>>>> and RC timing circuits too.
>>>>>
>>>>> Is there an anlytical way to express delay lines? I think I
>>>>> saw the delay case once, in a test for PE registration as a
>>>>> Controls Engineer.
>>>>>
>>>>>
>>>>
>>>> H(f) = exp(-j 2 pi f tau)
>>>
>>> Yes, but I think he means the Telegrapher's Equations:
>>>
>>> .<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>
>>
>> Maybe. I use the one I gave much more often. It’s dead useful for
>> modeling temperature controllers—you model the plant as a delay
>> followed by an integrator.
>>
>> You then do a bump test, i.e. dump a half-scale current step into
>> the TE cooler and measure the temperature response.
>>
>> You can read the model parameters right off the scope trace, or use
>> a micro and auto tune.

>
> What about startup slewing?

That's actually the beauty of the bump test autotune approach.

Any time you've got a slow plant that you want to speed up by adding
gain, you have to worry about windup. That's not too hard though--you
just stop updating the integrator during slew.

With TE coolers, the main issue is actually plain ol' linear overshoot.
For a given cooler and heat sink, there's a drive current value where
d(Tcold)/ dI crosses zero. At that point, the sign of the loop gain
inverts, which leads to Bad Things.

If your controller is underdamped, it's easy for the overshoot to put
you in that territory, so you design the autotuning to give you 70
degrees or so of phase margin, which will prevent that from happening.
(Obviously you put in some belt'n'braces safeguards as well.)

To get good bandwidth with a TEC loop, I usually make the cold plate out
of FR4 with lots of via stitching, with a bare ENIG pour up against the
TEC. One or two 0603 thermistors solder to the pour, right beside the
edge of the TEC. That's good for control bandwidths up to a couple of
hertz with small coolers.

(TECs are quicker than you might think--the cooling happens right where
the PbTe bars solder to the alumina, whereas the I2R heating is
distributed fairly uniformly along their length.)
>
> We use Spice to model fairly high-order tremperature controllers and
> the small-signal loop response is only part of the concern. A recent
> customer wanted an optical modulator to get stable to 0.05c in one
> hour from cold start, and that's substantially nonlinear.

How hard that is depends almost entirely on its physical size. If it
gets too big, you wind up having to use multiple zones, which gets
complicated in a hurry.

> The hard part of simming that is modeling diffusion and estimating
> heat losses to ambient from various surfaces of the oven box.

Diffusion isn't that difficult in homogeneous materials. If you have a
squint at Section 20.3 in my thermal control chapter,

<https://electrooptical.net/static/media/uploads/hobbsbeos3echapter20.pdf>,
I go into a lot of that stuff in a semi-analytical way that has been
super useful. Dunno about your particular case, of course, but most of
mine have used a lot of chunks of homogeneous material. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Thu, 17 Aug 2023 16:29:53 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>Joe Gwinn <joegwinn@comcast.net> wrote:
>> On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>
>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>>
>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>
>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>>>> prowl the web, take a nap.
>>>>>>>>
>>>>>>>> https://xkcd.com/303/
>>>>>>>>
>>>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>>>> settled in about an hour.
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> It?s probably pretty linear, so you could solve the DE by hand. Then you?d
>>>>>>> have more info than a stack of sims.
>>>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>>>> bypass caps. I'm not smart enough to do that analytically.
>>>>>
>>>>> Unless all those subelements interact, it's insane to simulate the
>>>>> whole shebang at once.
>>>>
>>>> Of course they interact!
>>>>
>>>> The 200 watt floating dc/dc conveter is reasonably independent so
>>>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>>> raw 48v bus in to the dc/dc.
>>>>
>>>> High school trig was some time ago, so I have a couple of sims to
>>>> verify the basic 3-phase math. Spice could eventually destroy all our
>>>> math skills; I use it for voltage dividers and RC timing circuits too.
>>>>
>>>> Is there an anlytical way to express delay lines? I think I saw the
>>>> delay case once, in a test for PE registration as a Controls Engineer.
>>>>
>>>>
>>>
>>> H(f) = exp(-j 2 pi f tau)
>>
>> Yes, but I think he means the Telegrapher's Equations:
>>
>> .<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>
>
>Maybe. I use the one I gave much more often. It’s dead useful for modeling
>temperature controllers—you model the plant as a delay followed by an
>integrator.
>
>You then do a bump test, i.e. dump a half-scale current step into the TE
>cooler and measure the temperature response.
>
>You can read the model parameters right off the scope trace, or use a micro
>and auto tune.

Yes. Is the PE test for Control Engineers that advanced?

Joe Gwinn

On Thu, 17 Aug 2023 14:27:05 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>
>On 2023-08-17 13:07, John Larkin wrote:
>> On Thu, 17 Aug 2023 16:29:53 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>
>>> Joe Gwinn <joegwinn@comcast.net> wrote:
>>>> On Thu, 17 Aug 2023 15:36:39 -0000 (UTC), Phil Hobbs
>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>
>>>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>>>>
>>>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John
>>>>>>> Larkin wrote:
>>>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>>>
>>>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com>
>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> While my sim is running, I can do all sorts of
>>>>>>>>>> things. Grocery shop, prowl the web, take a nap.
>>>>>>>>>>
>>>>>>>>>> https://xkcd.com/303/
>>>>>>>>>>
>>>>>>>>>> Same idea. My alternator simulator simulation (!)
>>>>>>>>>> takes about 25 minutes to rev up, running 10 or so
>>>>>>>>>> PPM of real time. It's nicely settled in about an
>>>>>>>>>> hour.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> It?s probably pretty linear, so you could solve the DE
>>>>>>>>> by hand. Then you?d have more info than a stack of
>>>>>>>>> sims.
>>>>>>>> It's a mess of PWM modulators, mosfet half-bridges,
>>>>>>>> cycle-by-cycle current limiters, 3-phase common-mode
>>>>>>>> chokes, ferrite beads, about 50 bypass caps. I'm not
>>>>>>>> smart enough to do that analytically.
>>>>>>>
>>>>>>> Unless all those subelements interact, it's insane to
>>>>>>> simulate the whole shebang at once.
>>>>>>
>>>>>> Of course they interact!
>>>>>>
>>>>>> The 200 watt floating dc/dc conveter is reasonably
>>>>>> independent so that's a separate sim. Ditto my soft-start
>>>>>> circuit that ramps up the raw 48v bus in to the dc/dc.
>>>>>>
>>>>>> High school trig was some time ago, so I have a couple of
>>>>>> sims to verify the basic 3-phase math. Spice could eventually
>>>>>> destroy all our math skills; I use it for voltage dividers
>>>>>> and RC timing circuits too.
>>>>>>
>>>>>> Is there an anlytical way to express delay lines? I think I
>>>>>> saw the delay case once, in a test for PE registration as a
>>>>>> Controls Engineer.
>>>>>>
>>>>>>
>>>>>
>>>>> H(f) = exp(-j 2 pi f tau)
>>>>
>>>> Yes, but I think he means the Telegrapher's Equations:
>>>>
>>>> .<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>
>>>
>>> Maybe. I use the one I gave much more often. It’s dead useful for
>>> modeling temperature controllers—you model the plant as a delay
>>> followed by an integrator.
>>>
>>> You then do a bump test, i.e. dump a half-scale current step into
>>> the TE cooler and measure the temperature response.
>>>
>>> You can read the model parameters right off the scope trace, or use
>>> a micro and auto tune.
>
>>
>> What about startup slewing?
>
>That's actually the beauty of the bump test autotune approach.
>
>Any time you've got a slow plant that you want to speed up by adding
>gain, you have to worry about windup. That's not too hard though--you
>just stop updating the integrator during slew.
>
>With TE coolers, the main issue is actually plain ol' linear overshoot.
> For a given cooler and heat sink, there's a drive current value where
>d(Tcold)/ dI crosses zero. At that point, the sign of the loop gain
>inverts, which leads to Bad Things.
>
>If your controller is underdamped, it's easy for the overshoot to put
>you in that territory, so you design the autotuning to give you 70
>degrees or so of phase margin, which will prevent that from happening.
>(Obviously you put in some belt'n'braces safeguards as well.)
>
>To get good bandwidth with a TEC loop, I usually make the cold plate out
>of FR4 with lots of via stitching, with a bare ENIG pour up against the
>TEC. One or two 0603 thermistors solder to the pour, right beside the
>edge of the TEC. That's good for control bandwidths up to a couple of
>hertz with small coolers.
>
>(TECs are quicker than you might think--the cooling happens right where
>the PbTe bars solder to the alumina, whereas the I2R heating is
>distributed fairly uniformly along their length.)
>>
>> We use Spice to model fairly high-order tremperature controllers and
>> the small-signal loop response is only part of the concern. A recent
>> customer wanted an optical modulator to get stable to 0.05c in one
>> hour from cold start, and that's substantially nonlinear.
>
>How hard that is depends almost entirely on its physical size. If it
>gets too big, you wind up having to use multiple zones, which gets
>complicated in a hurry.
>
>> The hard part of simming that is modeling diffusion and estimating
>> heat losses to ambient from various surfaces of the oven box.
>
>Diffusion isn't that difficult in homogeneous materials. If you have a
>squint at Section 20.3 in my thermal control chapter,
>
><https://electrooptical.net/static/media/uploads/hobbsbeos3echapter20.pdf>,
>I go into a lot of that stuff in a semi-analytical way that has been
>super useful. Dunno about your particular case, of course, but most of
>mine have used a lot of chunks of homogeneous material. ;)
>
>Cheers
>
>Phil Hobbs

Here's the eo gadget oven, with the big top off.

https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?dl=0

The eo modulator is inside the oven, on a secondary platform on some
not super thermally conductive spacers. The temp sensor, a
two-thermistor wheatstone bridge, is on the bottom of the platform
with a flex cable going down to the controller. The heaters are a lot
of mosfets on the bottom of the big box.

The platform adds a second lag to the loop, which lowpass filters temp
transients a bit but mostly prevents temp gradients from getting into
the eo modulator.

That's a dual-stage Mach-Zender modulator, which depends on
cancellation of a zillion light wavelengths against a zillion and some
plus 0.5 wavelengths, so it's pretty temperature sensitive and the
customer wants extreme extinction.

It was Spiced and came out about as expected.

The coax cables conduct heat too, which was measured and included in
the model.

On a sunny day (Thu, 17 Aug 2023 11:55:31 -0400) it happened Joe Gwinn
<joegwinn@comcast.net> wrote in <5igsdil470i700j5tmrei4fus3es26lurv@4ax.com>:

>Yes, but I think he means the Telegrapher's Equations:
>
>.<https://en.wikipedia.org/wiki/Telegrapher%27s_equations>

Thank you, nice link.

On Thursday, August 17, 2023 at 11:04:11 AM UTC-4, John Larkin wrote:
> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
> >> <pcdhSpamM...@electrooptical.net> wrote:
> >>
> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
> >> >>
> >> >>
> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
> >> >> prowl the web, take a nap.
> >> >>
> >> >> https://xkcd.com/303/
> >> >>
> >> >> Same idea. My alternator simulator simulation (!) takes about 25
> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
> >> >> settled in about an hour.
> >> >>
> >> >>
> >> >
> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
> >> >have more info than a stack of sims.
> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
> >> bypass caps. I'm not smart enough to do that analytically.
> >
> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
> Of course they interact!
>
> The 200 watt floating dc/dc conveter is reasonably independent so
> that's a separate sim. Ditto my soft-start circuit that ramps up the
> raw 48v bus in to the dc/dc.
>
> High school trig was some time ago, so I have a couple of sims to
> verify the basic 3-phase math. Spice could eventually destroy all our
> math skills; I use it for voltage dividers and RC timing circuits too.
>
> Is there an anlytical way to express delay lines? I think I saw the
> delay case once, in a test for PE registration as a Controls Engineer.

f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.

On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>> >> <pcdhSpamM...@electrooptical.net> wrote:
>> >>
>> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>> >> >>
>> >> >>
>> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
>> >> >> prowl the web, take a nap.
>> >> >>
>> >> >> https://xkcd.com/303/
>> >> >>
>> >> >> Same idea. My alternator simulator simulation (!) takes about 25
>> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> >> >> settled in about an hour.
>> >> >>
>> >> >>
>> >> >
>> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>> >> >have more info than a stack of sims.
>> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>> >> bypass caps. I'm not smart enough to do that analytically.
>> >
>> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>> Of course they interact!
>>
>> The 200 watt floating dc/dc conveter is reasonably independent so
>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>> raw 48v bus in to the dc/dc.
>>
>> High school trig was some time ago, so I have a couple of sims to
>> verify the basic 3-phase math. Spice could eventually destroy all our
>> math skills; I use it for voltage dividers and RC timing circuits too.
>>
>> Is there an anlytical way to express delay lines? I think I saw the
>> delay case once, in a test for PE registration as a Controls Engineer.
>
>f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.

LT Spice has both ideal and lossy transmission lines. A lossy line is
a decent model for a diffusive thing, like a thermal delay or a really
terrible PCB trace.

I think conductors inside digital ICs are essentially all diffusive, R
and C and not much L. That's terrible for rise time.

On Friday, August 18, 2023 at 10:25:58 AM UTC-4, John Larkin wrote:
> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
> >On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
> >> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
> >> <bloggs.fred...@gmail.com> wrote:
> >> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
> >> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
> >> >> <pcdhSpamM...@electrooptical.net> wrote:
> >> >>
> >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
> >> >> >>
> >> >> >>
> >> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
> >> >> >> prowl the web, take a nap.
> >> >> >>
> >> >> >> https://xkcd.com/303/
> >> >> >>
> >> >> >> Same idea. My alternator simulator simulation (!) takes about 25
> >> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
> >> >> >> settled in about an hour.
> >> >> >>
> >> >> >>
> >> >> >
> >> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
> >> >> >have more info than a stack of sims.
> >> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
> >> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
> >> >> bypass caps. I'm not smart enough to do that analytically.
> >> >
> >> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
> >> Of course they interact!
> >>
> >> The 200 watt floating dc/dc conveter is reasonably independent so
> >> that's a separate sim. Ditto my soft-start circuit that ramps up the
> >> raw 48v bus in to the dc/dc.
> >>
> >> High school trig was some time ago, so I have a couple of sims to
> >> verify the basic 3-phase math. Spice could eventually destroy all our
> >> math skills; I use it for voltage dividers and RC timing circuits too.
> >>
> >> Is there an anlytical way to express delay lines? I think I saw the
> >> delay case once, in a test for PE registration as a Controls Engineer.
> >
> >f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
> LT Spice has both ideal and lossy transmission lines. A lossy line is
> a decent model for a diffusive thing, like a thermal delay or a really
> terrible PCB trace.
>
> I think conductors inside digital ICs are essentially all diffusive, R
> and C and not much L. That's terrible for rise time.

By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.

On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>> >On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>> >> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>> >> <bloggs.fred...@gmail.com> wrote:
>> >> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>> >> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>> >> >> <pcdhSpamM...@electrooptical.net> wrote:
>> >> >>
>> >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>> >> >> >>
>> >> >> >>
>> >> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
>> >> >> >> prowl the web, take a nap.
>> >> >> >>
>> >> >> >> https://xkcd.com/303/
>> >> >> >>
>> >> >> >> Same idea. My alternator simulator simulation (!) takes about 25
>> >> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> >> >> >> settled in about an hour.
>> >> >> >>
>> >> >> >>
>> >> >> >
>> >> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>> >> >> >have more info than a stack of sims.
>> >> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>> >> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>> >> >> bypass caps. I'm not smart enough to do that analytically.
>> >> >
>> >> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>> >> Of course they interact!
>> >>
>> >> The 200 watt floating dc/dc conveter is reasonably independent so
>> >> that's a separate sim. Ditto my soft-start circuit that ramps up the
>> >> raw 48v bus in to the dc/dc.
>> >>
>> >> High school trig was some time ago, so I have a couple of sims to
>> >> verify the basic 3-phase math. Spice could eventually destroy all our
>> >> math skills; I use it for voltage dividers and RC timing circuits too.
>> >>
>> >> Is there an anlytical way to express delay lines? I think I saw the
>> >> delay case once, in a test for PE registration as a Controls Engineer.
>> >
>> >f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
>> LT Spice has both ideal and lossy transmission lines. A lossy line is
>> a decent model for a diffusive thing, like a thermal delay or a really
>> terrible PCB trace.
>>
>> I think conductors inside digital ICs are essentially all diffusive, R
>> and C and not much L. That's terrible for rise time.
>
>By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.

My super slow sim now is the PM alternator simulator board, which
doesn't have any delay lines.

https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1

That took a half hour or so to run. Even zooming on a slice of time
takes something like a minute. I guess I need to tell it to not save
so much stuff.

I have used lossy delay lines to simulate thermal systems, where the
lag between the heater and the temp sensor is diffusive. Thermal
systems have the equivalent of R and C but no equivalent of L.

On Fri, 18 Aug 2023 11:29:17 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

>On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
><bloggs.fredbloggs.fred@gmail.com> wrote:
>
>>On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
>>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
>>> <bloggs.fred...@gmail.com> wrote:
>>> >On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>>> >> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>> >> <bloggs.fred...@gmail.com> wrote:
>>> >> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>> >> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>> >> >> <pcdhSpamM...@electrooptical.net> wrote:
>>> >> >>
>>> >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>> >> >> >>
>>> >> >> >>
>>> >> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
>>> >> >> >> prowl the web, take a nap.
>>> >> >> >>
>>> >> >> >> https://xkcd.com/303/
>>> >> >> >>
>>> >> >> >> Same idea. My alternator simulator simulation (!) takes about 25
>>> >> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>> >> >> >> settled in about an hour.
>>> >> >> >>
>>> >> >> >>
>>> >> >> >
>>> >> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>>> >> >> >have more info than a stack of sims.
>>> >> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>> >> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>> >> >> bypass caps. I'm not smart enough to do that analytically.
>>> >> >
>>> >> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>>> >> Of course they interact!
>>> >>
>>> >> The 200 watt floating dc/dc conveter is reasonably independent so
>>> >> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>> >> raw 48v bus in to the dc/dc.
>>> >>
>>> >> High school trig was some time ago, so I have a couple of sims to
>>> >> verify the basic 3-phase math. Spice could eventually destroy all our
>>> >> math skills; I use it for voltage dividers and RC timing circuits too.
>>> >>
>>> >> Is there an anlytical way to express delay lines? I think I saw the
>>> >> delay case once, in a test for PE registration as a Controls Engineer.
>>> >
>>> >f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
>>> LT Spice has both ideal and lossy transmission lines. A lossy line is
>>> a decent model for a diffusive thing, like a thermal delay or a really
>>> terrible PCB trace.
>>>
>>> I think conductors inside digital ICs are essentially all diffusive, R
>>> and C and not much L. That's terrible for rise time.
>>
>>By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.
>
>My super slow sim now is the PM alternator simulator board, which
>doesn't have any delay lines.
>
>https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1
>
>That took a half hour or so to run. Even zooming on a slice of time
>takes something like a minute. I guess I need to tell it to not save
>so much stuff.
>

I tried .save of a few nodes and it didn't change the sim time much.
I'm compute bound.

Zooming should improve if I don't save gigabytes of data.

On Friday, August 18, 2023 at 7:52:37 PM UTC+1, John Larkin wrote:
> On Fri, 18 Aug 2023 11:29:17 -0700, John Larkin
> <jlarkin@highland_atwork_technology.com> wrote:
>
> >On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
> ><bloggs.fred...@gmail.com> wrote:
> >
> >>On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
> >>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
> >>> <bloggs.fred...@gmail.com> wrote:
> >>> >On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
> >>> >> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
> >>> >> <bloggs.fred...@gmail.com> wrote:
> >>> >> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
> >>> >> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
> >>> >> >> <pcdhSpamM...@electrooptical.net> wrote:
> >>> >> >>
> >>> >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
> >>> >> >> >>
> >>> >> >> >>
> >>> >> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
> >>> >> >> >> prowl the web, take a nap.
> >>> >> >> >>
> >>> >> >> >> https://xkcd.com/303/
> >>> >> >> >>
> >>> >> >> >> Same idea. My alternator simulator simulation (!) takes about 25
> >>> >> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
> >>> >> >> >> settled in about an hour.
> >>> >> >> >>
> >>> >> >> >>
> >>> >> >> >
> >>> >> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
> >>> >> >> >have more info than a stack of sims.
> >>> >> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
> >>> >> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
> >>> >> >> bypass caps. I'm not smart enough to do that analytically.
> >>> >> >
> >>> >> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
> >>> >> Of course they interact!
> >>> >>
> >>> >> The 200 watt floating dc/dc conveter is reasonably independent so
> >>> >> that's a separate sim. Ditto my soft-start circuit that ramps up the
> >>> >> raw 48v bus in to the dc/dc.
> >>> >>
> >>> >> High school trig was some time ago, so I have a couple of sims to
> >>> >> verify the basic 3-phase math. Spice could eventually destroy all our
> >>> >> math skills; I use it for voltage dividers and RC timing circuits too.
> >>> >>
> >>> >> Is there an anlytical way to express delay lines? I think I saw the
> >>> >> delay case once, in a test for PE registration as a Controls Engineer.
> >>> >
> >>> >f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
> >>> LT Spice has both ideal and lossy transmission lines. A lossy line is
> >>> a decent model for a diffusive thing, like a thermal delay or a really
> >>> terrible PCB trace.
> >>>
> >>> I think conductors inside digital ICs are essentially all diffusive, R
> >>> and C and not much L. That's terrible for rise time.
> >>
> >>By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.
> >
> >My super slow sim now is the PM alternator simulator board, which
> >doesn't have any delay lines.
> >
> >https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1
> >
> >That took a half hour or so to run. Even zooming on a slice of time
> >takes something like a minute. I guess I need to tell it to not save
> >so much stuff.
> >
> I tried .save of a few nodes and it didn't change the sim time much.
> I'm compute bound.
>
> Zooming should improve if I don't save gigabytes of data.

Give SIMPLIS a try, you'll speed simulations up by an order of magnitude.

On Fri, 18 Aug 2023 12:04:28 -0700 (PDT), John May <sunaeco@gmail.com>
wrote:

>On Friday, August 18, 2023 at 7:52:37?PM UTC+1, John Larkin wrote:
>> On Fri, 18 Aug 2023 11:29:17 -0700, John Larkin
>> <jlarkin@highland_atwork_technology.com> wrote:
>>
>> >On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
>> ><bloggs.fred...@gmail.com> wrote:
>> >
>> >>On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
>> >>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
>> >>> <bloggs.fred...@gmail.com> wrote:
>> >>> >On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>> >>> >> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>> >>> >> <bloggs.fred...@gmail.com> wrote:
>> >>> >> >On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>> >>> >> >> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>> >>> >> >> <pcdhSpamM...@electrooptical.net> wrote:
>> >>> >> >>
>> >>> >> >> >John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>> >>> >> >> >>
>> >>> >> >> >>
>> >>> >> >> >> While my sim is running, I can do all sorts of things. Grocery shop,
>> >>> >> >> >> prowl the web, take a nap.
>> >>> >> >> >>
>> >>> >> >> >> https://xkcd.com/303/
>> >>> >> >> >>
>> >>> >> >> >> Same idea. My alternator simulator simulation (!) takes about 25
>> >>> >> >> >> minutes to rev up, running 10 or so PPM of real time. It's nicely
>> >>> >> >> >> settled in about an hour.
>> >>> >> >> >>
>> >>> >> >> >>
>> >>> >> >> >
>> >>> >> >> >It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>> >>> >> >> >have more info than a stack of sims.
>> >>> >> >> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>> >>> >> >> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>> >>> >> >> bypass caps. I'm not smart enough to do that analytically.
>> >>> >> >
>> >>> >> >Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>> >>> >> Of course they interact!
>> >>> >>
>> >>> >> The 200 watt floating dc/dc conveter is reasonably independent so
>> >>> >> that's a separate sim. Ditto my soft-start circuit that ramps up the
>> >>> >> raw 48v bus in to the dc/dc.
>> >>> >>
>> >>> >> High school trig was some time ago, so I have a couple of sims to
>> >>> >> verify the basic 3-phase math. Spice could eventually destroy all our
>> >>> >> math skills; I use it for voltage dividers and RC timing circuits too.
>> >>> >>
>> >>> >> Is there an anlytical way to express delay lines? I think I saw the
>> >>> >> delay case once, in a test for PE registration as a Controls Engineer.
>> >>> >
>> >>> >f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
>> >>> LT Spice has both ideal and lossy transmission lines. A lossy line is
>> >>> a decent model for a diffusive thing, like a thermal delay or a really
>> >>> terrible PCB trace.
>> >>>
>> >>> I think conductors inside digital ICs are essentially all diffusive, R
>> >>> and C and not much L. That's terrible for rise time.
>> >>
>> >>By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.
>> >
>> >My super slow sim now is the PM alternator simulator board, which
>> >doesn't have any delay lines.
>> >
>> >https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1
>> >
>> >That took a half hour or so to run. Even zooming on a slice of time
>> >takes something like a minute. I guess I need to tell it to not save
>> >so much stuff.
>> >
>> I tried .save of a few nodes and it didn't change the sim time much.
>> I'm compute bound.
>>
>> Zooming should improve if I don't save gigabytes of data.
>
>Give SIMPLIS a try, you'll speed simulations up by an order of magnitude.

I'm really used to LT Spice, and it's great for most things. This one
case runs really slow.

One selling point for LT Spice is all the part models that are
available. How does SIMPLIS compare in that respect?

I really want 5000:1 speedup and sliders on parts so I can tweak and
see results instantly, like a breadboard with a trimpot and a scope.

Our big e/o modulator oven was slow in sim *and* in real time!
Realtime was worse. What a nuisance.

On 2023-08-18 20:52, John Larkin wrote:
> On Fri, 18 Aug 2023 11:29:17 -0700, John Larkin
> <jlarkin@highland_atwork_technology.com> wrote:
>
>> On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>
>>> On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
>>>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
>>>> <bloggs.fred...@gmail.com> wrote:
>>>>> On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>>>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>>>> <bloggs.fred...@gmail.com> wrote:
>>>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>>>
>>>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>>>>>> prowl the web, take a nap.
>>>>>>>>>>
>>>>>>>>>> https://xkcd.com/303/
>>>>>>>>>>
>>>>>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>>>>>> settled in about an hour.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>>>>>>>>> have more info than a stack of sims.
>>>>>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>>>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>>>>>> bypass caps. I'm not smart enough to do that analytically.
>>>>>>>
>>>>>>> Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>>>>>> Of course they interact!
>>>>>>
>>>>>> The 200 watt floating dc/dc conveter is reasonably independent so
>>>>>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>>>>> raw 48v bus in to the dc/dc.
>>>>>>
>>>>>> High school trig was some time ago, so I have a couple of sims to
>>>>>> verify the basic 3-phase math. Spice could eventually destroy all our
>>>>>> math skills; I use it for voltage dividers and RC timing circuits too.
>>>>>>
>>>>>> Is there an anlytical way to express delay lines? I think I saw the
>>>>>> delay case once, in a test for PE registration as a Controls Engineer.
>>>>>
>>>>> f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
>>>> LT Spice has both ideal and lossy transmission lines. A lossy line is
>>>> a decent model for a diffusive thing, like a thermal delay or a really
>>>> terrible PCB trace.
>>>>
>>>> I think conductors inside digital ICs are essentially all diffusive, R
>>>> and C and not much L. That's terrible for rise time.
>>>
>>> By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.
>>
>> My super slow sim now is the PM alternator simulator board, which
>> doesn't have any delay lines.
>>
>> https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1
>>
>> That took a half hour or so to run. Even zooming on a slice of time
>> takes something like a minute. I guess I need to tell it to not save
>> so much stuff.
>>
>
> I tried .save of a few nodes and it didn't change the sim time much.
> I'm compute bound.
>
> Zooming should improve if I don't save gigabytes of data.
>

The way you go about it, no amount of computing power is ever going
to be enough.

Jeroen Belleman

On Fri, 18 Aug 2023 22:02:36 +0200, jeroen <jeroen@nospam.please>
wrote:

>On 2023-08-18 20:52, John Larkin wrote:
>> On Fri, 18 Aug 2023 11:29:17 -0700, John Larkin
>> <jlarkin@highland_atwork_technology.com> wrote:
>>
>>> On Fri, 18 Aug 2023 10:42:16 -0700 (PDT), Fred Bloggs
>>> <bloggs.fredbloggs.fred@gmail.com> wrote:
>>>
>>>> On Friday, August 18, 2023 at 10:25:58?AM UTC-4, John Larkin wrote:
>>>>> On Fri, 18 Aug 2023 05:59:38 -0700 (PDT), Fred Bloggs
>>>>> <bloggs.fred...@gmail.com> wrote:
>>>>>> On Thursday, August 17, 2023 at 11:04:11?AM UTC-4, John Larkin wrote:
>>>>>>> On Thu, 17 Aug 2023 06:18:11 -0700 (PDT), Fred Bloggs
>>>>>>> <bloggs.fred...@gmail.com> wrote:
>>>>>>>> On Thursday, August 17, 2023 at 6:47:11?AM UTC-4, John Larkin wrote:
>>>>>>>>> On Thu, 17 Aug 2023 00:11:11 -0000 (UTC), Phil Hobbs
>>>>>>>>> <pcdhSpamM...@electrooptical.net> wrote:
>>>>>>>>>
>>>>>>>>>> John Larkin <jlarkin@highland_atwork_technology.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> While my sim is running, I can do all sorts of things. Grocery shop,
>>>>>>>>>>> prowl the web, take a nap.
>>>>>>>>>>>
>>>>>>>>>>> https://xkcd.com/303/
>>>>>>>>>>>
>>>>>>>>>>> Same idea. My alternator simulator simulation (!) takes about 25
>>>>>>>>>>> minutes to rev up, running 10 or so PPM of real time. It's nicely
>>>>>>>>>>> settled in about an hour.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> It’s probably pretty linear, so you could solve the DE by hand. Then you’d
>>>>>>>>>> have more info than a stack of sims.
>>>>>>>>> It's a mess of PWM modulators, mosfet half-bridges, cycle-by-cycle
>>>>>>>>> current limiters, 3-phase common-mode chokes, ferrite beads, about 50
>>>>>>>>> bypass caps. I'm not smart enough to do that analytically.
>>>>>>>>
>>>>>>>> Unless all those subelements interact, it's insane to simulate the whole shebang at once.
>>>>>>> Of course they interact!
>>>>>>>
>>>>>>> The 200 watt floating dc/dc conveter is reasonably independent so
>>>>>>> that's a separate sim. Ditto my soft-start circuit that ramps up the
>>>>>>> raw 48v bus in to the dc/dc.
>>>>>>>
>>>>>>> High school trig was some time ago, so I have a couple of sims to
>>>>>>> verify the basic 3-phase math. Spice could eventually destroy all our
>>>>>>> math skills; I use it for voltage dividers and RC timing circuits too.
>>>>>>>
>>>>>>> Is there an anlytical way to express delay lines? I think I saw the
>>>>>>> delay case once, in a test for PE registration as a Controls Engineer.
>>>>>>
>>>>>> f(t) delayed by Td is f(t-Td). Now how that works in LTSpice is another question. They do have some kind of delay function for digital subcircuits. So maybe analog->digital-> delay-> analog is the way to squeeze that into a realistic simulation.
>>>>> LT Spice has both ideal and lossy transmission lines. A lossy line is
>>>>> a decent model for a diffusive thing, like a thermal delay or a really
>>>>> terrible PCB trace.
>>>>>
>>>>> I think conductors inside digital ICs are essentially all diffusive, R
>>>>> and C and not much L. That's terrible for rise time.
>>>>
>>>> By diffusive I take it to mean frequency dependent time delay. That's much more complicated than a simple time shift. No wonder your runtime is taking forever. Do you really need to model these diffusive delays for a relay driver board??? Seems overkill.
>>>
>>> My super slow sim now is the PM alternator simulator board, which
>>> doesn't have any delay lines.
>>>
>>> https://www.dropbox.com/scl/fi/atrtd0s0euasg0jkq3p8p/P942_23.jpg?rlkey=sis6iqz3e8uiovk3qnmvjr3gd&raw=1
>>>
>>> That took a half hour or so to run. Even zooming on a slice of time
>>> takes something like a minute. I guess I need to tell it to not save
>>> so much stuff.
>>>
>>
>> I tried .save of a few nodes and it didn't change the sim time much.
>> I'm compute bound.
>>
>> Zooming should improve if I don't save gigabytes of data.
>>
>
>The way you go about it, no amount of computing power is ever going
>to be enough.

The way *I* go about it? How would you sim a polyphase switching
supply, simulating an alternator, driving a FADEC shorting regulator?

My old Win7 computer and LT Spice is a bit leisurely. But good enough.

>
>Jeroen Belleman

I want Spice to run on an Nvidia board.