Spice is great!...

[John Larkin]

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.

 

[Phil Hobbs]

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

 

[John Larkin]

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

 

[Fred Bloggs]

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

 

[Jan Panteltje]

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.

 

[John Larkin]

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.

 

[John Larkin]

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.

 

[Phil Hobbs]

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

 

[Anthony William Sloman]

On Friday, August 18, 2023 at 1:04:11 AM UTC+10, 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:

<snip>

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

Of course there is. Williams and Taylor (ISBN 0 -07-070434-1) tell you how to build linear phase low pass and all-pass filters, which is to say structures which offer a constant delay over a range of frequencies, and they give you the analytic forms of these filters.

--
Bill Sloman, Sydney

 

[Joe Gwinn]

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

 

[Phil Hobbs]

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

 

[jeroen]

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

 

[John Larkin]

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.

 

[Phil Hobbs]

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

 

[Joe Gwinn]

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

 

[John Larkin]

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.

 

[Jan Panteltje]

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.

 

[Fred Bloggs]

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.

 

[John Larkin]

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.

 

[Fred Bloggs]

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.