¿ªÔÆÌåÓý

  1. LTspice
  2. Topics

3722 Power Supply Problem

 

Hello,

I am trying to make a power supply using a 3722-1.

The input is 18 to 30Vdc and output is [email protected].

The issue that I am having is that at low input voltages like 24V or 18V the power supply is not able to reach full output level. At 30V the output level is reached but regulation is poor.

Please help:

I have the schematic posted here:
 

The file got moved it is here
now:;
48AVlS9HgGiTRn6rGS43KClNpbTNJJfkSVOXq1-IaKjYLCMgtJOdg_5Au/%20Temp/Power%\
20Supply%203722.asc
 

On 12/07/2013 18:12, viperlenny wrote:
The file got moved it is here
now:;
48AVlS9HgGiTRn6rGS43KClNpbTNJJfkSVOXq1-IaKjYLCMgtJOdg_5Au/%20Temp/Power%\
20Supply%203722.asc
The "f1" URLS are temporary and can't be re-used....


--
Dave Wade G4UGM
Illegitimi Non Carborundum
 

Missing MODEL for the STTH3R04S diodes.
 

--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:

Missing MODEL for the STTH3R04S diodes.


[Non-text portions of this message have been removed]
I swapped to a different diode, hopefully you have model for this one, but any 300V or higher diode should work.

New file is here:
 

--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:

Missing MODEL for the STTH3R04S diodes.


[Non-text portions of this message have been removed]
Here is the model for this diode:
.model STTH3R04S D(IS=1.3998E-6 N=2.4797 RS=29.052E-3 IKF=91.895E-3 CJO=31.776E-12 M=.22102 VJ=.3905 ISR=10.010E-21 NR=4.9950 FC=0.5 TT=5.000E-9 Iave=3 Vpk=400 mfg=ST_Micro. type=silicon)
 


The file got moved it is here
Neither of you has it quite right.

Any time you post a long URL that begins with "
(anything with "yahoofs" in it), it doesn't help because that URL is good
for you only, and only for a few minutes. Try going there now and it won't
work.

The schematic file is here:

Files > Temp > Power Supply 3722.asc



It's missing at least one model, so it won't run.

Andy
 

--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:


The file got moved it is here
Neither of you has it quite right.

Any time you post a long URL that begins with "
(anything with "yahoofs" in it), it doesn't help because that URL is good
for you only, and only for a few minutes. Try going there now and it won't
work.

The schematic file is here:

Files > Temp > Power Supply 3722.asc



It's missing at least one model, so it won't run.

Andy


[Non-text portions of this message have been removed]
Here is the model:
.model STTH3R04S D(IS=1.3998E-6 N=2.4797 RS=29.052E-3 IKF=91.895E-3 CJO=31.776E-12 M=.22102 VJ=.3905 ISR=10.010E-21 NR=4.9950 FC=0.5 TT=5.000E-9 Iave=3 Vpk=400 mfg=ST_Micro. type=silicon)

And here is an updated file with a different diode:
 

--- In LTspice@..., "viperlenny" <viperlenny@...> wrote:

Hello,

I am trying to make a power supply using a 3722-1.

The input is 18 to 30Vdc and output is 165V@...

The issue that I am having is that at low input voltages like 24V or 18V the power supply is not able to reach full output level. At 30V the output level is reached but regulation is poor.
There's nothing wrong with the model, as such, but there seems to be a couple of issues with the circuit that you're simulating.

If you overcompensate it, you'll get a better idea about what is going on in the power train, as the control circuit will not be responsible for cycle by cycle variations.

There should be an overcompensated example posted in the temp files shortly.

In the working model, there is a shoot-through current occurring quite regularly. I don't know whether this is the result of intentional values placed in the drive delay circuits.

In real life, such spikes would invoke irregular limiting behavior in the 3722 that you'll want to avoid.

As to power throughput with reducing input voltage, you should take a look at the current waveforms and decide for yourself where the limitation lays.

RL
 

RL,

Thank you for taking a look but I still have an issue. The bridge nodes that you renamed now disconnected the ZVS circuit of the chip because the nodes have been renamed to SWAB and SWCD the SWT and SWB nodes are no longer connected and are left floating.

Also when the when the input power supply drops to 18V the regulation of the 165V rail is not kept.

I would also appreciate it if you could tell me how you came to derive all of the compensation values.

Thanks for your help.

Leo

--- In LTspice@..., legg@... wrote:



--- In LTspice@..., "viperlenny" <viperlenny@> wrote:

Hello,

I am trying to make a power supply using a 3722-1.

The input is 18 to 30Vdc and output is 165V@

The issue that I am having is that at low input voltages like 24V or 18V the power supply is not able to reach full output level. At 30V the output level is reached but regulation is poor.
There's nothing wrong with the model, as such, but there seems to be a couple of issues with the circuit that you're simulating.

If you overcompensate it, you'll get a better idea about what is going on in the power train, as the control circuit will not be responsible for cycle by cycle variations.

There should be an overcompensated example posted in the temp files shortly.

In the working model, there is a shoot-through current occurring quite regularly. I don't know whether this is the result of intentional values placed in the drive delay circuits.

In real life, such spikes would invoke irregular limiting behavior in the 3722 that you'll want to avoid.

As to power throughput with reducing input voltage, you should take a look at the current waveforms and decide for yourself where the limitation lays.

RL
 

Well that explains most of the shoot-through. You don't see any when the nodes are reconnected?

The compensation values are overkill. Feel free to fiddle with or remove any of them. Just watch what the IC comp pin does during start-up and line/load variations, though, as you make your changes.

As has been suggested elsewhere, the large inductance values of your transformer are prime limitations to power transfer, when current is expected to reverse each cycle. The leakage inductance induces extra dead-time in the output rectifier, robbing you of headroom.

Also, with the turns ratio used, at 18V, you're close to drop-out anyways. If you expect to induce double output current peaks in the output inductor, you'll need extra headroom.

It is strange conjunction of power train component values. How did you select them? You'd normally think of magnetizing current as a fraction of that being transferred, unless it was aggravated intentionally to perform some other function.

RL

--- In LTspice@..., "viperlenny" <viperlenny@...> wrote:

RL,

Thank you for taking a look but I still have an issue. The bridge nodes that you renamed now disconnected the ZVS circuit of the chip because the nodes have been renamed to SWAB and SWCD the SWT and SWB nodes are no longer connected and are left floating.

Also when the when the input power supply drops to 18V the regulation of the 165V rail is not kept.

I would also appreciate it if you could tell me how you came to derive all of the compensation values.

Thanks for your help.

Leo

--- In LTspice@..., legg@ wrote:



--- In LTspice@..., "viperlenny" <viperlenny@> wrote:

Hello,

I am trying to make a power supply using a 3722-1.

The input is 18 to 30Vdc and output is 165V@

The issue that I am having is that at low input voltages like 24V or 18V the power supply is not able to reach full output level. At 30V the output level is reached but regulation is poor.
There's nothing wrong with the model, as such, but there seems to be a couple of issues with the circuit that you're simulating.

If you overcompensate it, you'll get a better idea about what is going on in the power train, as the control circuit will not be responsible for cycle by cycle variations.

There should be an overcompensated example posted in the temp files shortly.

In the working model, there is a shoot-through current occurring quite regularly. I don't know whether this is the result of intentional values placed in the drive delay circuits.

In real life, such spikes would invoke irregular limiting behavior in the 3722 that you'll want to avoid.

As to power throughput with reducing input voltage, you should take a look at the current waveforms and decide for yourself where the limitation lays.

RL

1 - 11 of 11