1000w smps based on LUDO3232

Upik

Member
yes I understand now, for the primer on my smps to reach 350v, if to divide a smaller voltage, for example 150v, does the dividing resistor have to be adjusted too?
with the scope specifications I have, with a max input of 40v peak, is it safe for Silvio, ??
 
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Silvio

Well-known member
The resistive divider will also work for lower voltage of 150v. it will divide by 10 and the voltage at the probe will be 15v.

Note During test do not touch laptop or scope. Be careful !!!
 
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Silvio

Well-known member
what if using a 2x47k (2 watts) 10k (2watt), is that not a problem in reading

The wattage in the resistors is there so that they do not burn with the voltage applied to them. If you have larger watt resistors its no problem.

This is how I worked it. There is around 350v volts at the primary so first we work out the current with ohms law

V= I x R so V/R =I so 350v / 100000 ohms = 0.0035A or 3.5mA

W = V x I so 350v x 0.0035A = 1.225W

You have to choose a larger watt resistor than 1.2W because it will heat up a lot however I divided the resistor of 100k with 2 x 47k so that the power will be divided. However most of the voltage drop will be in the 47K resistors. The 10K resistor will not have a lot of voltage drop in it so 1watt will be enough.

I hope that helps.
 

Silvio

Well-known member
hi mr. silvio, do you like the power class D driver ... ??

Yes they are very efficient and could reach 95% efficiency. Compared to class AB amplifier which is around 65% eff. This mean you need less power from the power supply for class D amplifier.
 

Upik

Member
I'm working on a class D project, if I have tested it, I want to share the file with you, only to you, silvio
 

Silvio

Well-known member
Hello Mr/Ms Silvio!
Thank you for your circuit.
But I wonder how feedback signal work?
Thank you!

If you are referring to my schematic with SG3525 and IR2110
The feedback works by taking a sample of the output voltage which is compared with the reference voltage of the TL431. When the voltage of the output goes higher the led inside the opto coupler will light up and switching the photo transistor inside the opto and this in turn switches pin 1 of the sg3525 to ground thus reducing the pulse width hence also the output voltage. A balance is maintained so that the output voltage remains constant.

The 33v zener is there because the TL431 cannot take more voltage than this. As you can see from the schematic the output voltage is much higher (more than 100v).
 

vuhotay

New member
Thank you sir!
I am very worry before going to page 19 and I see your v2 version and I see your feedback circuit.
Thank you!
 

vuhotay

New member
Hello Mr Silvo!
I did your project and I have some problems with output voltage. Max voltage I got is 73v with no feedback. And I test on 150W light the voltage down to 68v. I have no more light to reach 1000W. But i wonder does IR2110 have auto feedback? And how do you think about being can not get more voltage? although I set to 97% of pwm.
Hope your reply!
 

Silvio

Well-known member
Hello Mr Silvo!
I did your project and I have some problems with output voltage. Max voltage I got is 73v with no feedback. And I test on 150W light the voltage down to 68v. I have no more light to reach 1000W. But i wonder does IR2110 have auto feedback? And how do you think about being can not get more voltage? although I set to 97% of pwm.
Hope your reply!

About the output voltage it depends on the turns in the transformer Pri and secondary and also the input AC voltage.
The smps is not regulated and has no feedback. The output voltage will sag a little with load.

Please tell me what you did in the transformer turns and also measure your input ac voltage.

If you are using ETD49 transformer then the turns should be 18 turns for primary and 9-0-9 turns for secondary. You will only get 80v-0-80v if the input voltage is 240vac with less the output voltage will be less.

You will get voltage drop with load at a maximum of 10 to 15% depending on the value of input capacitance and also how good you wind the transformer. If you are going to use the unregulated version then you will not need output inductor. Short out the place where the inductor should be with a piece of copper wire and solder it. The inductor will create voltage drop

Send some photos so we can see what you did.
 
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Silvio

Well-known member
Thank you sir!
I am very worry before going to page 19 and I see your v2 version and I see your feedback circuit.
Thank you!

Regarding the feed back circuit well you have to include the output inductor otherwise it will not work. The output voltage will be set to around 60v do not try to go higher as there is not enough headroom in the output to sustain it.
 

vuhotay

New member
I tested these ones on the picture and the more turn inductor be wraped the more drop voltage are. And I think I am wrong with transformer. I did 29 turns for pri and 7-0-7 for sec on EE49 core. I will rebuilt and send feedback to you!20190407_085855.jpg
 
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Silvio

Well-known member
What type of transformer do you actually have is it an ETD or EE type?
What output voltage do you need?
 

vuhotay

New member
I used a grinding CRT TV flyback transformer. I didn't know that is ETD or EE core. I set the primary for 18 turns and 2 mosfets are blow up. although with 29 turns everything did well. Today I will rebuilt a new PCB and do it again!
Please tell me what is difference between ETD and EE core?
 

Silvio

Well-known member
You can search the internet to see what is an ETD and EE core.

I suggest you see this video before trying to wind the transformer. link below

https://www.youtube.com/watch?v=TLD6hUV64YU&t=1s

See also this video to help you understand what you should do to wind a safe transformer,

https://www.youtube.com/watch?v=_K3ixhcTYFg&t=1s

You are doing this at your own risk and I am not responsible in any way.

remember that the mains voltage is deadly and if you electrocute yourself it may be fatal and you die.

read the SMPS warnings at the top bar of the page.
 
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