Re: PSUD possible issue on corner case power supply
As the current doesn't instantaneously drop to zero in real life, the voltage generated will be limited.? HOWEVER, your power line is not a perfect sine wave forever... there are inductive devices being switched elsewhere, lightning induces impulses, even without a direct hit, and of course your supply gets turned on and off. As a result, ANY solid-state rectifier used with a choke-input filter should have overvoltage protection - an MOV (between DC max and diode PIV rating) or a small value input cap will do.? In an industrial application, I saw a 1400V, 240A three-phase bridge (used on 208VAC) that would fail every few hundred on/off cycles. A .047 uF across output fixed it for good.
Tom Bavis
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On 4/20/2022 12:31 PM, Paul Reid wrote: On 4/20/2022 7:18 AM, Duncan Munro wrote:
There are various formulae around for figuring out the correct minimum choke value Try "Figure out the load resistance, E/I (Volts, Amps), then divide that by 1200. The result is in Henries."
In 50Hz lands use "1000".
So for 24VDC and 0.6A we have 40r, divide by 1200 is 0.034H.
Or for 50Hz, 40r, divide by 1000 is 0.040H. (40mH)
You have 0.007H. Less than 1/5th what the formula suggests for minimum.
Yes, it may kick violently.
Other tip: whenever possible! don't use "current sources". No practical component acts as a perfect current source. I suspect if you replace your I1 with a 40 Ohm you will still get kicks but not divide-by-zero spikes of a math model.
I would also simplify first. Your R1 and C2 probably have little effect on the kicking and rectifier stress.
However none of this changes the fact that 6.8mH is much too small for a 24V 0.6A load. The simplified supply shows (as Duncan says) choke current going to zero every half-cycle, which spoils the advantage of a choke-input filter, while adding the fun of "infinite" voltage kicks.
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Re: PSUD possible issue on corner case power supply
On 4/20/2022 7:18 AM, Duncan Munro wrote: There are various formulae around for figuring out the correct minimum choke value Try "Figure out the load resistance, E/I (Volts, Amps), then divide that by 1200. The result is in Henries." In 50Hz lands use "1000". So for 24VDC and 0.6A we have 40r, divide by 1200 is 0.034H. Or for 50Hz, 40r, divide by 1000 is 0.040H. (40mH) You have 0.007H. Less than 1/5th what the formula suggests for minimum. Yes, it may kick violently. Other tip: whenever possible! don't use "current sources". No practical component acts as a perfect current source. I suspect if you replace your I1 with a 40 Ohm you will still get kicks but not divide-by-zero spikes of a math model. I would also simplify first. Your R1 and C2 probably have little effect on the kicking and rectifier stress. However none of this changes the fact that 6.8mH is much too small for a 24V 0.6A load. The simplified supply shows (as Duncan says) choke current going to zero every half-cycle, which spoils the advantage of a choke-input filter, while adding the fun of "infinite" voltage kicks.
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Re: PSUD possible issue on corner case power supply
There could be a danger of damage to the rectifier; the problem is the choke value being too low.
It's essential on a choke supply for the current to be continuous through the choke without dropping to zero at any point during steady state operation. If it's doing this, you need a bigger value, and it's a good idea to monitor I(L1) to see what is happening and yield some great clues as to what will work and what won't work.
Had a look at your circuit and the current collapses to zero during the cycle due to the low choke value, this will cause the voltage to head towards infinity until something breaks down, either insulation in the transformer or more likely the rectifier breaking over with the excess voltage. This could cause excess heating in the rectifier and subsequent failure. You can increase rectifier leakage for a visibly better result, however this is just a band aid for the underlying problem.
There are various formulae around for figuring out the correct minimum choke value, but I just did some hit and miss values and got 30mH as about as low as I'd want to go. If you try this value, or higher, it will give much better results.
Have a look at I(L1) without changing anything, then look again after upping the value to 30mH and you'll see the difference it makes. Hope this helps.
Regards,
Duncan
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PSUD possible issue on corner case power supply
PSUD gives me this result on a particular power supply (yes, the choke is underspecified on purpose).? Playing with rectifier leak mitigates the problem somewhat, but it still looks unnatural.? Is this a math problem or is my rectifier in actual danger of blowing up?
?
?
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Re: DHTRob PSUDII guide/tutorial
Is the 39 nF silver mica cap (between the HT legs) a correct value? I can only find 39 pF in Mouser catalog
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Re: DHTRob PSUDII guide/tutorial
Thank you Evert, I don't remember where to post the link but Duncan posted that the recommended "simulate" set is for "100ms" after a reporting delay of "0" S to see the best real ripple your PSU is doing.
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Re: DHTRob PSUDII guide/tutorial
very reliable info
well known amp builder?
evert
Verstuurd vanaf mijn iPhone
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Op 26/03/2022 om 17:05 heeft felipe cerrillo vindel <fcv@...> het volgende geschreven:
?Attached DHTRob manual/guide, could I trust him? or do you have a better tutorial/guide to use PDUII?
TIA
Felipe
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Can you check the location that you're trying to load from using Windows Explorer (file manager), maybe by trying to rename a file to see if you have write access to the file. PSUD under Windows can only work within the permissions it's given from the OS, so I suspect this is outside of the control of the app.
If the files are somewhere that worked well years ago, but doesn't work well now, for example the Program Files area, you might need to copy and move them to somewhere more "friendly" and it may ask you to temporarily elevate to Administrator privileges to to do it.
Regards,
Duncan
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DHTRob PSUDII guide/tutorial
Attached DHTRob manual/guide, could I trust him? or do you have a better tutorial/guide to use PDUII?
TIA
Felipe
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Win 10,? kept current.? Build 76.
Thanks,
Jack
On 3/26/2022 9:30 AM, Duncan Munro
wrote:
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Would need to know about your setup: Type of operating system
(MacOS / Windows), version/build of PSUD from Help|About.
Regards,
Duncan
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Would need to know about your setup: Type of operating system (MacOS / Windows), version/build of PSUD from Help|About.
Regards,
Duncan
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I haven't used this for a while and now find that I cannot open any of my saved .psu files.? Looks like some permissions issue.? Any suggestions?
Thanks,
73 Jack KZ5A
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Hello Duncan,
Thanks again, attached requested rectifiers.txt file.
Kind rgds
Felipe
Hi Felipe,
It may be you are using the more modern version of PSUD II which doesn't use rectifiers.txt? If you go to Help -> About it will tell you the version number. If it's build 74 (version 2.20.0) or higher, then rectifiers.txt is replaced by individual .rect files
to make it easier to share rectifier models around.
There are the following resources available to help with the later .rect files:
- The help file under Technical Information gives a short description of how to add your own rectfiers
- There is a YouTube video at??which talks through the process in more detail
- There are some support spreadsheets to go along with the video on this groups.io page at?/g/duncanampspsud/files/documentation
If you have an earlier version before 74 then something is badly wrong, but it sounds like you have the later version.
Regards,
Duncan
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Hi Felipe, This is the old version so the previous advice will not help you. Could you please email your rectifiers.txt file to me at postmaster@... and I will take a look at it for you, thanks. Regards, Duncan
?
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Hi Duncan,
Thanks for support, attached screenshot.
Best regards
Felipe
Hi Felipe,
It may be you are using the more modern version of PSUD II which doesn't use rectifiers.txt? If you go to Help -> About it will tell you the version number. If it's build 74 (version 2.20.0) or higher, then rectifiers.txt is replaced by individual .rect files
to make it easier to share rectifier models around.
There are the following resources available to help with the later .rect files:
- The help file under Technical Information gives a short description of how to add your own rectfiers
- There is a YouTube video at??which talks through the process in more detail
- There are some support spreadsheets to go along with the video on this groups.io page at?/g/duncanampspsud/files/documentation
If you have an earlier version before 74 then something is badly wrong, but it sounds like you have the later version.
Regards,
Duncan
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Hi Felipe, It may be you are using the more modern version of PSUD II which doesn't use rectifiers.txt? If you go to Help -> About it will tell you the version number. If it's build 74 (version 2.20.0) or higher, then rectifiers.txt is replaced by individual .rect files to make it easier to share rectifier models around. There are the following resources available to help with the later .rect files:
- The help file under Technical Information gives a short description of how to add your own rectfiers
- There is a YouTube video at??which talks through the process in more detail
- There are some support spreadsheets to go along with the video on this groups.io page at?/g/duncanampspsud/files/documentation
If you have an earlier version before 74 then something is badly wrong, but it sounds like you have the later version. Regards, Duncan
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I added some rectifiers to rectifiers.txt, but when open PSUDII aren't available?
TIA for help
Felipe
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Hi Chris, I had this issue a while back, it's security related. Please check Message #20 within this group for some suggestions that may help. Regards, Duncan
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Good morning. ?Running MacOS 12.1 Monterey. ? When I opened psud this morning, I got the following error popups.
Clicked "OK" in both cases to ignore, but psud does not open.
Downloaded build 77, but got the exact same error messages . . . ??
Any ideas?
Chris
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Hi Duncan,
The small resistances are the wire.
The circuit is as built in the amp. I know I can parallel up the
parts and had done so in the initial run.
effective saves 10s in execution, gains 10s in delay.
I ran into OOM issues with much simpler circuits and similar delays.
The power supply does take a while to stabilize on a plain old VOM
from a cold start.
AND PLEASE fix Save As... to the same folder as the orig and
preserve the name to allow me to make a Rev change if I load from
recent on the File menu ?
C:\Users\%user%\AppData\Roaming\psud\examples??? Never!!!!
- Ian
On 12/12/2021 12:01, Duncan Munro
wrote:
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Hi Ian,
This circuit is problematic in a significant number of places.
R1 - 10 milliohm resistor goes into 40uF capacitor with series
resistance of 4.24 ohms and an inductor with resistance of 25
ohms. I'm really not getting what that 10 milliohm resistor is
doing for you? All it will do is force the simulator to review the
tiny RC constant of 10milliohm/40uF into smaller and smaller
timesteps until it breaks or you run out of memory.
Similar with C2/C3/C4 and R2/R3 balancing them. Again, this will
force the timesteps to be very small and consume memory. These are
loops with potentially high currents that can only be balanced
with microscopic time steps (long sim times and lots of memory).
C2/C3/C4 can be replaced with one 600uF capacitor with ESR of the
three resistances in parallel. R2/R3 can be removed - they are not
contributing materially to the PSU output.
A power supply shouldn't take 80 seconds to stabilise, this will
exacerbate the problem. As will running high accuracy with the
aforementioned values that the simulator will struggle to balance.
Regards,
Duncan
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Paul Reid
Ian Eales