Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
On Sun, Jul 9, 2023 at 12:05 AM, Jerry Lee Marcel wrote:
The 74HC model is missing.
Sorry, I uploaded it too.
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Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
On Sat, Jul 8, 2023 at 11:30 PM, Andy I wrote:
Kerim,
But your 3-winding transformer:
- is really just a 2-winding transformer but with a center-tapped primary (does that matter?);
- is "perfect", with no leakage inductance.
If the leakage inductance is responsible for the transformer's low-pass filtering, the 3-winding transformer lacks any.? What did you do to it when tweaking it to act as an LPF?? You did not leave your tweaks on the schematic, right?
Andy
Andy, You are right in all you said. I was somehow shy to upload what I tried doing because their responses were rather ridiculous :( So, I uploaded the schematic with a conventional 3-winding transformer so that it could be replaced with a practical model and tested. Kerim
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Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
The 74HC model is missing.
Le 08/07/2023 ¨¤ 21:03, Kerim via
groups.io a ¨¦crit?:
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Show quoted text
Hello,
Please find the
uploaded two schematics in ¡®PureSineInv.zip¡¯:
[1] Sinewave
inverter using a bridge to drive a two-winding linear
transformer with no load and whose model include somehow its
parasite LPF elements.
[2] Sinewave
inverter using a push-pull drive for three-winding linear
transformer (loaded) whose model doesn¡¯t include its parasite
LPF elements.
In vain, I tried tweaking the three-winding linear transformer
to let it act as a LPF as done on the schematic [1].
I hope that someone can do it for me in any possible way or
notify me that it cannot be done, at least for LTspice.
Your help will be
much appreciated.
(In these days, I cannot afford building a push-pull inverter
and its 3-winding transformer, even for 500W only, to find out
that the PWM high frequency, about 16 KHz (Tpwm=64us), cannot be
filtered out as it was done in the case of the full-bridge.)??
?
Best Regards,
Kerim
|
Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
Kerim, But your 3-winding transformer:
- is really just a 2-winding transformer but with a center-tapped primary (does that matter?);
- is "perfect", with no leakage inductance.
If the leakage inductance is responsible for the transformer's low-pass filtering, the 3-winding transformer lacks any.? What did you do to it when tweaking it to act as an LPF?? You did not leave your tweaks on the schematic, right? Andy
|
Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
More: You don't see any LPF
effect because you set K to 1, so there is no leakage
inductance. If you set K to say 0.98 you will see a filtering
effect.
======================================================================================
Best wishes
John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget.
I see, and I remember.
I do, and I understand.
Xunzi (340 - 245 BC)
On 2023-07-08 21:22, John Woodgate
wrote:
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Present: far too much stuff
not relevant to the question of the transformer acting as a
low-pass filter.
Kerim, if you accept that a
two-winding transformer acts as a low-pass filter, you
should be able to see that the presence of a third winding
doesn't change that.? The leakage inductance and the load
resistance are still there, as for the two-winding
transformer.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do, and I
understand. Xunzi (340 - 245 BC)
On 2023-07-08 21:13, Andy I wrote:
Missing:
? ? 74hc86.asy
? ? 74hc.lib
Andy
|
Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
Present: far too much stuff not
relevant to the question of the transformer acting as a
low-pass filter.
Kerim, if you accept that a
two-winding transformer acts as a low-pass filter, you should
be able to see that the presence of a third winding doesn't
change that.? The leakage inductance and the load resistance
are still there, as for the two-winding transformer.
======================================================================================
Best wishes
John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget.
I see, and I remember.
I do, and I understand.
Xunzi (340 - 245 BC)
On 2023-07-08 21:13, Andy I wrote:
toggle quoted message
Show quoted text
Missing:
? ? 74hc86.asy
? ? 74hc.lib
Andy
|
Re: Push-Pull 3-Winding Transformer Model Acting as LPF too?
Missing:
? ? 74hc86.asy
? ? 74hc.lib
Andy
|
Re: Periodic signal from PWL file
Whoa. I haven't seen of seen BNF for several decades (I think the last I saw it was sgen learnjng Modula-2).
DaveD
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On Jul 8, 2023, at 14:48, Donald H Locker via groups.io <dhlocker@...> wrote:
?
Backus-Nauer Form! (commonly just "BNF")
Donald.
On 2023-07-08 14:45, John Woodgate
wrote:
Regular expression?
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do, and I
understand. Xunzi (340 - 245 BC)
On 2023-07-08 19:43, Donald H Locker
via groups.io wrote:
That is a "logical OR"? separating two optional forms of the
command or of a command's parameters.
There is a formal mechanism for language specification (whose
name I can't remember despite using is so many times for so
long...).
If I manage to remember, I'll toss it your way.
Donald.
On 2023-07-08 11:56, Christoph
wrote:
Fine so far, but using the | (vertical bar) gives an error.
PWL REPEAT FOREVER
(file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt)
ENDREPEAT works, while
PWL REPEAT FOREVER (|
file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt)
ENDREPEAT
doesn¡¯t So what is the purpose of the ?|¡®?
¡ª
Christoph
Am 08.07.2023 um 17:52 schrieb John
Woodgate < jmw@...>:
If you look at the other examples
on that page, you will see that the |
character is only used with a file, not with a
sequence of numbers.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do,
and I understand. Xunzi (340 - 245 BC)
On 2023-07-08 16:40,
Christoph wrote:
Thanks. This worked. Though the ?|¡® symbol (pipe)
is confusing. If it designates that the data is
supposed to be piped from the file, it doesn¡¯t
work. OTOH, should it mean an ?or¡°, then the empty
left side of the ?|¡® shouldn¡¯t be empty but
contain a
list of <time><value>
pairs.
¡ª
Christoph
Am 08.07.2023 um 15:11 schrieb
John Woodgate < jmw@...>:
There is an
undocumented REPEAT feature in the
Wiki at: /g/LTspice/wiki/13810
A
list of data points or a file
reference can be repeated a
fixed amount of times <n>,
or forever
PWL REPEAT FOR
<n> (|<file spec>)
ENDREPEAT
PWL REPEAT FOREVER
(|<file spec>) ENDREPEAT
======================================================================================
Best wishes John Woodgate OOO-Own
Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I
remember. I do, and I understand.
Xunzi (340 - 245 BC)
On
2023-07-08 13:51, Christoph wrote:
I have created a pulse source from a PWL file.
It¡®s 32 samples of a signal.
Is it possible to make this pulse train periodic?
Or do I have to provide the pulse samples for every period by the PWL file?
¡ª
Christoph
|
Push-Pull 3-Winding Transformer Model Acting as LPF too?
Hello,
Please find the uploaded two schematics in ¡®PureSineInv.zip¡¯:
[1] Sinewave inverter using a bridge to drive a two-winding linear transformer with no load and whose model include somehow its parasite LPF elements.
[2] Sinewave inverter using a push-pull drive for three-winding linear transformer (loaded) whose model doesn¡¯t include its parasite LPF elements.
In vain, I tried tweaking the three-winding linear transformer to let it act as a LPF as done on the schematic [1].
I hope that someone can do it for me in any possible way or notify me that it cannot be done, at least for LTspice.
Your help will be much appreciated.
(In these days, I cannot afford building a push-pull inverter and its 3-winding transformer, even for 500W only, to find out that the PWM high frequency, about 16 KHz (Tpwm=64us), cannot be filtered out as it was done in the case of the full-bridge.)??
?
Best Regards,
Kerim
|
Re: Periodic signal from PWL file
Backus-Nauer Form! (commonly just "BNF")
Donald.
On 2023-07-08 14:45, John Woodgate
wrote:
toggle quoted message
Show quoted text
Regular expression?
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do, and I
understand. Xunzi (340 - 245 BC)
On 2023-07-08 19:43, Donald H Locker
via groups.io wrote:
That is a "logical OR"? separating two optional forms of the
command or of a command's parameters.
There is a formal mechanism for language specification (whose
name I can't remember despite using is so many times for so
long...).
If I manage to remember, I'll toss it your way.
Donald.
On 2023-07-08 11:56, Christoph
wrote:
Fine so far, but using the | (vertical bar) gives an error.
PWL REPEAT FOREVER
(file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt)
ENDREPEAT works, while
PWL REPEAT FOREVER (|
file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt)
ENDREPEAT
doesn¡¯t So what is the purpose of the ?|¡®?
¡ª
Christoph
Am 08.07.2023 um 17:52 schrieb John
Woodgate < jmw@...>:
If you look at the other examples
on that page, you will see that the |
character is only used with a file, not with a
sequence of numbers.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do,
and I understand. Xunzi (340 - 245 BC)
On 2023-07-08 16:40,
Christoph wrote:
Thanks. This worked. Though the ?|¡® symbol (pipe)
is confusing. If it designates that the data is
supposed to be piped from the file, it doesn¡¯t
work. OTOH, should it mean an ?or¡°, then the empty
left side of the ?|¡® shouldn¡¯t be empty but
contain a
list of <time><value>
pairs.
¡ª
Christoph
Am 08.07.2023 um 15:11 schrieb
John Woodgate < jmw@...>:
There is an
undocumented REPEAT feature in the
Wiki at: /g/LTspice/wiki/13810
A
list of data points or a file
reference can be repeated a
fixed amount of times <n>,
or forever
PWL REPEAT FOR
<n> (|<file spec>)
ENDREPEAT
PWL REPEAT FOREVER
(|<file spec>) ENDREPEAT
======================================================================================
Best wishes John Woodgate OOO-Own
Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I
remember. I do, and I understand.
Xunzi (340 - 245 BC)
On
2023-07-08 13:51, Christoph wrote:
I have created a pulse source from a PWL file.
It¡®s 32 samples of a signal.
Is it possible to make this pulse train periodic?
Or do I have to provide the pulse samples for every period by the PWL file?
¡ª
Christoph
|
Re: Periodic signal from PWL file
Regular expression?
======================================================================================
Best wishes
John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget.
I see, and I remember.
I do, and I understand.
Xunzi (340 - 245 BC)
On 2023-07-08 19:43, Donald H Locker
via groups.io wrote:
toggle quoted message
Show quoted text
That is a "logical OR"? separating two optional forms of the
command or of a command's parameters.
There is a formal mechanism for language specification (whose
name I can't remember despite using is so many times for so
long...).
If I manage to remember, I'll toss it your way.
Donald.
On 2023-07-08 11:56, Christoph wrote:
Fine so far, but using the | (vertical bar) gives an error.
PWL REPEAT FOREVER
(file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt)
ENDREPEAT works, while
PWL REPEAT FOREVER (|
file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt) ENDREPEAT
doesn¡¯t So what is the purpose of the ?|¡®?
¡ª
Christoph
Am 08.07.2023 um 17:52 schrieb John Woodgate
< jmw@...>:
If you look at the other examples
on that page, you will see that the | character
is only used with a file, not with a sequence of
numbers.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do,
and I understand. Xunzi (340 - 245 BC)
On 2023-07-08 16:40,
Christoph wrote:
Thanks. This worked. Though the ?|¡® symbol (pipe) is
confusing. If it designates that the data is
supposed to be piped from the file, it doesn¡¯t work.
OTOH, should it mean an ?or¡°, then the empty left
side of the ?|¡® shouldn¡¯t be empty but contain a
list of <time><value>
pairs.
¡ª
Christoph
Am 08.07.2023 um 15:11 schrieb
John Woodgate < jmw@...>:
There is an
undocumented REPEAT feature in the
Wiki at: /g/LTspice/wiki/13810
A
list of data points or a file
reference can be repeated a fixed
amount of times <n>, or
forever
PWL REPEAT FOR
<n> (|<file spec>)
ENDREPEAT
PWL REPEAT FOREVER
(|<file spec>) ENDREPEAT
======================================================================================
Best wishes John Woodgate OOO-Own
Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I
remember. I do, and I understand. Xunzi
(340 - 245 BC)
On 2023-07-08
13:51, Christoph wrote:
I have created a pulse source from a PWL file.
It¡®s 32 samples of a signal.
Is it possible to make this pulse train periodic?
Or do I have to provide the pulse samples for every period by the PWL file?
¡ª
Christoph
|
Re: Periodic signal from PWL file
That is a "logical OR"? separating two optional forms of the
command or of a command's parameters.
There is a formal mechanism for language specification (whose
name I can't remember despite using is so many times for so
long...).
If I manage to remember, I'll toss it your way.
Donald.
On 2023-07-08 11:56, Christoph wrote:
toggle quoted message
Show quoted text
Fine so far, but using the | (vertical bar) gives an error.
PWL REPEAT FOREVER
(file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt) ENDREPEAT
works, while
PWL REPEAT FOREVER (|
file=Z:\Users\kuku\Documents\LTspiceXVII\pulses.txt) ENDREPEAT
doesn¡¯t So what is the purpose of the ?|¡®?
¡ª
Christoph
Am 08.07.2023 um 17:52 schrieb John Woodgate
< jmw@...>:
If you look at the other examples on
that page, you will see that the | character is
only used with a file, not with a sequence of
numbers.
======================================================================================
Best wishes John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I remember. I do, and
I understand. Xunzi (340 - 245 BC)
On 2023-07-08 16:40,
Christoph wrote:
Thanks. This worked. Though the ?|¡® symbol (pipe) is
confusing. If it designates that the data is supposed
to be piped from the file, it doesn¡¯t work. OTOH,
should it mean an ?or¡°, then the empty left side of
the ?|¡® shouldn¡¯t be empty but contain a
list of <time><value> pairs.
¡ª
Christoph
Am 08.07.2023 um 15:11 schrieb
John Woodgate < jmw@...>:
There is an
undocumented REPEAT feature in the
Wiki at: /g/LTspice/wiki/13810
A
list of data points or a file
reference can be repeated a fixed
amount of times <n>, or
forever
PWL REPEAT FOR
<n> (|<file spec>)
ENDREPEAT
PWL REPEAT FOREVER
(|<file spec>) ENDREPEAT
======================================================================================
Best wishes John Woodgate OOO-Own Opinions
Only
Rayleigh, Essex UK
I hear, and I forget. I see, and I
remember. I do, and I understand. Xunzi
(340 - 245 BC)
On 2023-07-08
13:51, Christoph wrote:
I have created a pulse source from a PWL file.
It¡®s 32 samples of a signal.
Is it possible to make this pulse train periodic?
Or do I have to provide the pulse samples for every period by the PWL file?
¡ª
Christoph
|
Re: PWL sources (was but not related to: "Discrete data points in plot view")
Further to Tony's point above:?
There is no "Dirac" function in LTSpice, that defines a value at one infinitesimal time.
?You need a slew-up time, a hold time, and a slew-down time - and three voltage values accordingly.?
Generally, these are most easily produced with a spreadsheet, rather than the limited PWL options.?
The PWL format could not be simpler, as a headerless 2-term CSV format, and it can even import and export wav files - see Simon Bramble's tutorials.?
regds
Bonkers?
|
Re: Periodic signal from PWL file
Thanks, Andy. I missed out on
the computer world from 1958 to the BBC Micro.
======================================================================================
Best wishes
John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget.
I see, and I remember.
I do, and I understand.
Xunzi (340 - 245 BC)
On 2023-07-08 18:06, Andy I wrote:
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Show quoted text
John asked, "What do you
understand 'file spec' to mean? Is it another term for
'filename'?"
Almost yes.? That is commonly what "file spec" (or "filespec")
means, except that a filespec may include the path, so it can be
the full location of a file on your drive, not just the filename
which is everything after the path (after the last "\") in the
filespec.
I thought everyone knew that already.? I guess not.? Sorry.
Andy
|
Re: Periodic signal from PWL file
John asked, "What do you understand 'file spec' to mean? Is it another term for 'filename'?"
Almost yes.? That is commonly what "file spec" (or "filespec") means, except that a filespec may include the path, so it can be the full location of a file on your drive, not just the filename which is everything after the path (after the last "\") in the filespec.
I thought everyone knew that already.? I guess not.? Sorry.
Andy
|
PWL sources (was but not related to: "Discrete data points in plot view")
The clue is in the name: Piece-Wise-Linear. In the waveform viewer, all the points are connected by straight lines. If you want impulses, you will have to create them.? But zero width impulses don't exist in the real world, so LTspice doesn't plot them that way. Each narrow impulse needs to consist of a minimum of 3 points.
-- Regards,
On 8 Jul 2023 17:52, Christoph <kuku@...> wrote: My array of PWL data (time value pairs) appears points (that optionally can be made visible) and being connected by line pieces.
Since these are discrete sample points I¡¯d rather see them as points only or as a pulse train of vertical lines of height corresponding to the amplitude. Is this possible?
¡ª
Christoph
|
Re: Periodic signal from PWL file
What do you understand 'file
spec' to mean? Is it another term for 'filename'? It would be
best to have uniform terminology.
======================================================================================
Best wishes
John Woodgate OOO-Own Opinions Only
Rayleigh, Essex UK
I hear, and I forget.
I see, and I remember.
I do, and I understand.
Xunzi (340 - 245 BC)
On 2023-07-08 17:42, Andy I wrote:
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Show quoted text
Here is my best guess.
I think "analog spiceman" authored that information about the
REPEAT ... ENDREPEAT syntax.? Maybe he meant to write it like
this:
... PWL REPEAT FOR <n> ( <t1> <v1> ...
<tn> <vn> | file=<file spec> ) ENDREPEAT
... PWL REPEAT FOREVER ( <t1> <v1> ... <tn>
<vn> | file=<file spec> ) ENDREPEAT
In other words, you have a choice between either the time,value
list, OR a filename.? I think that's why he used a "|" character
there, to show that you have a choice between options -- and
somehow the first one got edited out, as well as the "file=" in
the second choice.? But the "|" character itself is NOT part of
the syntax.
I don't know; but it works for me.
Andy
|
Discrete data points in plot view
Christoph,
For time-domain and frequency-domain plots, I think LTspice only connects the dots with lines or curves.? I think there is no other option.
I have seen .STEPped simulations where LTspice's plot window showed vertical lines, but this was actually annoying because it did not plot what I actually wanted to see.? So I have forgotten now how that happened.? I did not see it as something useful, at the time.??Anyway, I do not believe there is any option to make it do that, at least not when plotting waveforms vs. time.
I agree with John that you probably need to turn to another plotting program (e.g., Excel).
Also, FYI, even if your PWL data has discrete time points, it is likely that LTspice simulated between those time points.? Even if you could make LTspice (or Excel) plot only the simulated time points as dots or vertical lines, there would likely be values at times between the points of your PWL data.? This is just how SPICE has to work.? There are times when it needs to simulate between the raw data.? That cannot be changed.
So, if you used Excel, you could also filter out those time values that don't correspond to your PWL file's raw data.
Andy
|
Re: Periodic signal from PWL file
Here is my best guess.
I think "analog spiceman" authored that information about the REPEAT ... ENDREPEAT syntax.? Maybe he meant to write it like this:
... PWL REPEAT FOR <n> ( <t1> <v1> ... <tn> <vn> | file=<file spec> ) ENDREPEAT
... PWL REPEAT FOREVER ( <t1> <v1> ... <tn> <vn> | file=<file spec> ) ENDREPEAT
In other words, you have a choice between either the time,value list, OR a filename.? I think that's why he used a "|" character there, to show that you have a choice between options -- and somehow the first one got edited out, as well as the "file=" in the second choice.? But the "|" character itself is NOT part of the syntax.
I don't know; but it works for me.
Andy
|
Re: PWL sources (was but not related to: "Discrete data points in plot view")
The PWL function can be repeated,?
I'd advise that you read all the tutorials from Simon Bramble.?
If you're making custom PWL files, you'd be mad not to use a spreadsheet, and this can cover more functionality than the LTSpice PWL options.?
The principle of t_bit and t_slew applies just the same to spreadsheets - if you plot your raw signal as an x-y graph, you get triangle waves.? If you want square waves, you need to have a slew time, and 2 points per bit.?
|
John Woodgate
Bonkers
Tony Casey