.savestate directive no longer works
The .savestate directive? was introduced in version 24.1.0. I have existing files that worked with this directive.
Now, when I try to run any transient simulation I get this error "argument not found"
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However .loadstate still works if there was a file previously created with .savestate directive.
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I am running LTspice V.24.1.7.
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Example:?
.savestate file2 time= 10m? ? this directive has stopped working.??
.loadstate file2? ? ? this directive still works if file2 exists.
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Re: FFT of expression of voltages ?
#FFT
You can always create an auxiliary behavioral voltage/current source with the desired expression and get the FFT of that output.
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Re: Possible g;itch in stepping parameters
Is that*with* the incorrectly inserted? curlies?
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From: [email protected] <[email protected]>
On Behalf Of Mathias Born via groups.io
Sent: Thursday, May 01, 2025 1:10 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Possible g;itch in stepping parameters
?
What I mean is you would expect the parameters to just work.
Latest LTspice produces this .meas result:
? step ? ?{nCells}
? ? ?1 ? ?35.8704181146
? ? ?2 ? ?50.4427754736
? ? ?3 ? ?84.071292456
Measurement: nc2
? step ? ?{nCells2}
? ? ?1 ? ?42.947255402
? ? ?2 ? ?60.394577909
? ? ?3 ? ?100.657629848
On Thu, May 1, 2025 at 09:35 PM, Andy I wrote:
"Exactly as you expect ...". That's a tough one to define.? Care to elaborate, which way would be the "expected" one?
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Re: Possible g;itch in stepping parameters
What I mean is you would expect the parameters to just work.
Latest LTspice produces this .meas result:
?
Measurement: nc
? step ? ?{nCells}
? ? ?1 ? ?35.8704181146
? ? ?2 ? ?50.4427754736
? ? ?3 ? ?84.071292456
Measurement: nc2
? step ? ?{nCells2}
? ? ?1 ? ?42.947255402
? ? ?2 ? ?60.394577909
? ? ?3 ? ?100.657629848
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Best Regards,
Mathias
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On Thu, May 1, 2025 at 09:35 PM, Andy I wrote:
"Exactly as you expect ...". That's a tough one to define.? Care to elaborate, which way would be the "expected" one?
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Andy
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Re: Possible g;itch in stepping parameters
On 01/05/2025 12:47, Tony Casey via
groups.io wrote:
Remove
all the braces, then it will work as you want. You never need
braces anyway with .param directives.
If used with .meas xxx param yyy, you will only get one measured
value, as you observed. Sometimes, this can be what you want, but
not this time.
.step voc=45
tnom = 27
temp = 27
method = modified trap
.step voc=75
Measurement: nc
? step??? ncells
???? 1??? 35.8704
???? 2??? 50.4428
???? 3??? 84.0713
Measurement: nc2
? step??? ncells2
???? 1??? 42.9473
???? 2??? 60.3946
???? 3??? 100.658
Total elapsed time: 0.119 seconds.
--
Regards,
Tony
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Re: Possible g;itch in stepping parameters
"Exactly as you expect ...". That's a tough one to define.? Care to elaborate, which way would be the "expected" one?
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Andy
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Re: Possible g;itch in stepping parameters
Hi Dave,
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This works exactly as you expect in latest LTspice.
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Best Regards,
Mathias
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Re: FFT of expression of voltages ?
#FFT
Hi
And thanks all.
I try Andy's procedure :
- CTRL Click,..., ALT Double click and it works.
Nice !
And thanks again.
Bernard
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Re: FFT of expression of voltages ?
#FFT
On Thu, May 1, 2025 at 01:16 PM, Richard Andrews wrote:
I don't recall if it's left or right click, but click on the fft label for the node your measuring and enter your own expression in the evaluator.
It's a right-click.
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But it works only when the expression you want does not include any other node voltages or currents that were not already part of the FFT.? If you start with V(n001) and try changing it to V(n001,n007) or V(n001)-1.2*V(n007), it will not work unless V(n007) was already part of the FFT.? Getting that to work requires having both of them highlighted in the first FFT menu.
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Andy
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Re: FFT of expression of voltages ?
#FFT
I guess I misremembered.
On 2025-05-01 17:34, Andy I via
groups.io wrote:
On Thu, May 1, 2025 at 12:14 PM, John Woodgate wrote:
If you plot V(n001)-V(n007)first,
you can then get its FFT.
I tried that, and it did not work for me.? I plotted both
V(n001,n007) and V(n001)-V(n07) in the waveform viewer, and then
went to the FFT menu, but still got only the list of individual
voltages and currents in either case.
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Maybe that is a feature that exists in only some versions of
LTspice?? I'd be surprised if it does, but maybe.
Andy ?
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--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
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Re: FFT of expression of voltages ?
#FFT
I don't recall if it's left or right click, but click on the fft label for the node your measuring and enter your own expression in the evaluator.
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Re: FFT of expression of voltages ?
#FFT
On Thu, May 1, 2025 at 12:14 PM, John Woodgate wrote:
If you plot V(n001)-V(n007)first, you can then get its FFT.
I tried that, and it did not work for me.? I plotted both V(n001,n007) and V(n001)-V(n007) in the waveform viewer, and then went to the FFT menu, but still got only the list of individual voltages and currents in either case.
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Maybe that is a feature that exists in only some versions of LTspice?? I'd be surprised if it does, but maybe. Andy ?
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Re: FFT of expression of voltages ?
#FFT
On Thu, May 1, 2025 at 12:09 PM, <ba@...> wrote:
I use currently the FFT of single voltage or current and I would like to do the same with expressions like :
V(n001)-V(n007)
or other valid numerical expressions for instance in a current instance.
The easiest way to do that, is this:
- Start with the FFT menu (View > FFT).
- Highlight all of the node voltages or element currents that you wish to be used in your FFT formula.? (Hint: Use Ctrl-click to select, or Shift-Click to select a range.? These use the normal MS-Windows selection rules.)
- In your example, highlight both V(n001) and V(n007).
- Click OK.
- A second pop-up window follows, asking you to select which waveforms to actually plot.
- As instructed there, now use Alt-Double-Click to enter an expression.? At this point, it doesn't matter which one is now highlighted.
- Type the expression you desire.? You may use only the node voltages and element currents that were previously selected in the first FFT menu.
- Click OK.
Done.
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Once you get your FFT plot, you can further edit the formula if you desire, by right-clicking on the formula at the top of the plot.? Again, it can include only the voltages and currents that you had selected in the first FFT menu, so the important thing is to first select (highlight) all those voltages and currents which you might want to include in the expression.? Doing that instructs LTspice to find the FFT components of each of those individual voltages and currents - which you can then put into an editable formula.
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Alternatively, you could generate a separate signal on your schematic that represents your formula, and then simulate with it.? But I like doing it the other way, even if it is more steps to remember.
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Andy
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Re: FFT of expression of voltages ?
#FFT
If you plot V(n001)-V(n007)first, you
can then get its FFT.
On 2025-05-01 17:06, ba@...
wrote:
Hi all
I use currently the FFT of single voltage or current and I
would like to do the same with expressions like :
V(n001)-V(n007)
or other valid numerical expressions for instance in a
current instance.
I looked at the help and can't find how to ?
Thanks four your help.
Bernard
PS : I am using the last version : 24.1.7
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
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FFT of expression of voltages ?
#FFT
Hi all
I use currently the FFT of single voltage or current and I would like to do the same with expressions like :
V(n001)-V(n007)
or other valid numerical expressions for instance in a current instance.
I looked at the help and can't find how to ?
Thanks four your help.
Bernard
PS : I am using the last version : 24.1.7
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Re: Modeling Constant Power Load with AC Source in LTspice
On Thu, May 1, 2025 at 09:13 AM, Dennis wrote:
seems to trigger numerical instability in the solver when the change gets too large
With trap integration and the alternate solver the crossover voltage can be reduced to 70 V and it is barley able to run to completion. Plotting the voltage across the inductor shows the instability.
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Changing to gear integration adds damping to the solver which produces clean waveforms with the crossover at 70 V. Using gear integration the solver becomes unstable at a crossover voltage of about 40 V and fails with a crossover at 30 V.
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Re: Modeling Constant Power Load with AC Source in LTspice
On Thu, May 1, 2025 at 08:23 AM, Dennis wrote:
crossover power
That should be crossover voltage.
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With a low crossover voltage the peak current through B1 is very high (500 W / crossover voltage) before the current starts to drop towards zero at the zero crossing of the input voltage. This produces a current peak with a very large derivative when the switch from constant power to operation to polynomial resistive operation happens (i.e. at the crossover voltage). The voltage across the inductor then changes rapidly (V = L * di/dt) at the crossover point and seems to trigger numerical instability in the solver when the change gets too large.?
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Re: Modeling Constant Power Load with AC Source in LTspice
On Thu, May 1, 2025 at 07:38 AM, skyraider2 wrote:
Adding a 100uf cap across B1 gets the simulation to run.
The required capacitance depends upon the crossover power setting of B1. If the crossover is increased to 50 then only 1 uF is needed. If the crossover is increased to 100 then no capacitance is needed.??
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Re: Modeling Constant Power Load with AC Source in LTspice
Eaglesea
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Adding a 100uf cap across B1 gets the simulation to run.
I think the problem is an oscillation caused by putting a current source in series with an inductor.
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Dan
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Re: Possible g;itch in stepping parameters
On Thu, May 1, 2025 at 06:52 AM, Tony Casey wrote:
That's not quite true. In order for them to captured and printed in the logfile, the braces need to be removed. Then it will work.
Interesting!
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Andy
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Bell, Dave
Tony Casey
John Woodgate