Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

0-50V 0-10A Variable SMPS

Status
Not open for further replies.

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
Yes, also, i think the datasheet of LT124X does say that LT124X are pin for pin compatible with uc384x series.
I think the UCC38c4x series is also the same but draws less bias current, so you may prefer it.
Remember also you only need the 50% duty one as its 2TFC.
There is also the NCP12XX series which may do the trick.

Thats good news. I am gonna try to simulate with LTSpice. Yea i know, in 2T forward, above 50% duty cycle must be avoided in order not to saturate the main transformer. Thats why also i used UC3844 giving 50% duty cycle at most. I have taken 40% duty cycle at most in transformer calculations. Yea there are many alternatives for pwm and pfc ics but the problem is that we can not find them easily here. So i did select the common ones.
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
Yes, also, i think the datasheet of LT124X does say that LT124X are pin for pin compatible with uc384x series.
I think the UCC38c4x series is also the same but draws less bias current, so you may prefer it.
Remember also you only need the 50% duty one as its 2TFC.
There is also the NCP12XX series which may do the trick.

I tried to simulate in LTSpice but i encountered with annoying floating problems as always. Thats why i hate all simulation software. U can download the files at attachment. :bang:
 

Attachments

  • Simulation.rar
    8.2 KB · Views: 56
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
T

treez

Guest
sorry I don't have RAR file unzipper...I just tried to download a free one and it instead gave me some PC care software instead.
Maybe you should change the solver to "alternate 2", or "skip initial operating point"
Yes you cannot have floating nodes, you need to connect a ground, or connect a ground via a 10meg resistor say if you wish
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
sorry I don't have RAR file unzipper...I just tried to download a free one and it instead gave me some PC care software instead.
Maybe you should change the solver to "alternate 2", or "skip initial operating point"
Yes you cannot have floating nodes, you need to connect a ground, or connect a ground via a 10meg resistor say if you wish

Ok man thnx. I will try your solutions and give u feedback tomorrow. I can make the files as txt file so you can download and see.

15.7kB Draft1.txt = Draft1.asc
564 bayt Draft1 (2).txt = Draft1 (2).log
5.75kB Draft1 (3).txt = Draft1 (3).raw
2.84kB LM324.txt = LM324.mod
2.39kB LM324_test.txt = LM324_test.asc
 

Attachments

  • Draft1 (2).txt
    564 bytes · Views: 37
  • Draft1 (3).txt
    5.8 KB · Views: 28
  • Draft1.txt
    15.8 KB · Views: 35
  • LM324.txt
    2.8 KB · Views: 30
  • LM324_test.txt
    2.4 KB · Views: 30
Last edited:

T

treez

Guest
Ok I had a quik look at draft and you did not pick mosfet, you just put a fet symbol, you should pick an actual device or else it doesn't work. Also, I think you should use GND only and not "common". I also see you still use the 10u cap.
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
Ok I had a quik look at draft and you did not pick mosfet, you just put a fet symbol, you should pick an actual device or else it doesn't work. Also, I think you should use GND only and not "common". I also see you still use the 10u cap.

Ok thanks a lot. Yea i forgot to pick a mosfet. I used common since between gdt and main transformer must be isolated. I ll write the results tomorrow. Thnx.

And is there any disadvantage to use 10u cap ? If yes, then ofc i ll use the smaller one in value.
 

T

treez

Guest
yes you cannot get a true copy of the primary waveform with the 10u cap there...if you see the sim I sent to you, compare that with the one where you have 10u.
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
yes you cannot get a true copy of the primary waveform with the 10u cap there...if you see the sim I sent to you, compare that with the one where you have 10u.

Yes, you are right. I was not able to get true waveform of primary when i chose 10u cap but 330p cap is used to filter the spikes. For normal operation 330p is used in parallel with 1 - 4.7u cap. I always see such combination. But in LTSpice, when i use 10u cap it gives me a voltage up to 130V and not DC output.

By the way, although i changed the grounds, it didnt work. I also pick a mosfet for 2T forward and i think i am never gonna learn how to simulate correctly.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
T

treez

Guest
I woul RC filter the voltage across the "burden" resistor, not put a cap in parallel with it.
Simulation you only learn by trial and error. Sometimes my 100th simulation attempt works, the first version never works.
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
I woul RC filter the voltage across the "burden" resistor, not put a cap in parallel with it.
Simulation you only learn by trial and error. Sometimes my 100th simulation attempt works, the first version never works.

Thnx. In another forum, they say that i need to put dummy load at both SMPS and PFC outputs and maybe also need for flyback outputs. Do i really need these resistors and is there any specific calculation for them ?
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
yes, dummy load is V(out)/(Load current)

I have seen in a SMPS handbook, they use 1k resistor for 0-60V 0-5A output. But i cant put a 50V/10A = 5R resistor, it will waste of power. Maybe 1k resistor is suitable. It is common to draw a few mA from output i think. So if i put 1k, 50V^2 / 1k = 2.5W at most.
 

T

treez

Guest
as you know, the sim wont waste power like that, your circuit will, but I guess you have to test it on full load anyway, so please go ahead
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
as you know, the sim wont waste power like that, your circuit will, but I guess you have to test it on full load anyway, so please go ahead

Ok thnx. I will give you feedback.
 

T

treez

Guest
ok, I send you here good knowledge on current sense transformers...simulations etc

- - - Updated - - -

also, I send here a novel two transistor forward converter simulation etc...its simple and doesn't need gate drive transformers
 

Attachments

  • Current sense transformers.zip
    8.6 MB · Views: 103
  • Two transistor forward converter _Bootstrap drive.zip
    115.8 KB · Views: 69

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
ok, I send you here good knowledge on current sense transformers...simulations etc

- - - Updated - - -

also, I send here a novel two transistor forward converter simulation etc...its simple and doesn't need gate drive transformers

Thnx a lot man.

The schematics below are the final ones.
 

Attachments

  • control, output and power.jpg
    control, output and power.jpg
    751.2 KB · Views: 70
  • fan control.jpg
    fan control.jpg
    174.5 KB · Views: 62
  • pfc.jpg
    pfc.jpg
    834 KB · Views: 79
  • supply.jpg
    supply.jpg
    642 KB · Views: 83
  • voltage and current control.jpg
    voltage and current control.jpg
    417.5 KB · Views: 78
Last edited:

T

treez

Guest
**broken link removed**

The above (page 13-15 gives good knowledge on boost diode and fet for pfc...Infineon do an excellent range there, you could also use there EICE driver to get the gate turn off lop small, rather than the pnp.

I trust you used the power.com software to design the topswitch one. I think its called PIexpert.

- - - Updated - - -

I didn't see your opto feedback to uc3842...it should go to comp pin of uc3842, and fb pin should be grounded
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
**broken link removed**

The above (page 13-15 gives good knowledge on boost diode and fet for pfc...Infineon do an excellent range there, you could also use there EICE driver to get the gate turn off lop small, rather than the pnp.

I trust you used the power.com software to design the topswitch one. I think its called PIexpert.

- - - Updated - - -

I didn't see your opto feedback to uc3842...it should go to comp pin of uc3842, and fb pin should be grounded

Thnx for infineon app note. Yea i used PIexpert for flyback converter for supply.

UC3842 and PFC stage does not share same ground. I dont need a opto feedback. No need for isolation. Mine is similar to circuit below. Every supply, output are isolated from ac line.

http://danyk.cz/reg60v_en.html
 

T

treez

Guest
sorry but no you are using mains input...you need optocoupler or similar to give isolation, otherwise its very dangerous.
UC3842 and PFC surely share same ground...I mean, pfc provides vin for uc3842, they need same ground
 

fethiyeli

Full Member level 4
Joined
Feb 9, 2013
Messages
207
Helped
10
Reputation
20
Reaction score
12
Trophy points
1,298
Activity points
2,985
sorry but no you are using mains input...you need optocoupler or similar to give isolation, otherwise its very dangerous.
UC3842 and PFC surely share same ground...I mean, pfc provides vin for uc3842, they need same ground

UC3842 has GND but pfc has earth symbol. They dont have the same. Isolated VCC supplies to UC3842 ( i am gonna use uc3844 ) so there is no requirement for opto or isolation. Take a closer look to flyback supply.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top