Resonant SMPS using L6599

Silvio

Member
Hi Res, The circuit looks promising at a first glance, from what I have read so far these tend to be a bit sensitive and usually they are used for a constant load. I do not know what are your intentions for this smps being either for learning purposes or maybe to use it somewhere. I have never built one myself but I have seen some lectures on youtube by Sam Ben Yakovv. This man is a professor in a university teaching students. I suggest you follow some of these videos and learn the Math behind this topology.

As you may well know there are quite some types being in soft switching, Zero voltage switching or zero current switching. The task is to keep the smps at below or above resonance depending on the load requirements. This feature implies having a variable frequency controller that can sense the load current and adjusting the frequency to maintain the load current.

Well I wish you well and good luck in your experiments and hope that you succeed.

Regards Silvio
 

res_smps

New member
I have seen some lectures on youtube by Sam Ben Yakovv. This man is a professor in a university teaching students. I suggest you follow some of these videos and learn the Math behind this topology.
I will try to search on youtube, thank you

Because I was busy in my work in another field,
for now I don't have a purpose why I make smps (I have no financial goal), I make it just because I like electronics

I designed a smps with symmetrical output so that it can also be used for audio amplifiers especially for friends here

Actually I can do mathematical calculations, from what I learned, the calculation of the infineon AN-1160 is easier for manual calculations rather than appnote from ST.
attached L6599 excel spreadsheets for easy way.

I tried to explain in my writing how to make transformer construction easy for DIY because in my opinion this is one of the difficult parts of making a resonant converter

I've tried regulated and non regulated smps with the L6599 (and UCC25600) chip

test load (i can not test in a long time because nikelin wire burning my table)
https://www.youtube.com/watch?v=umJtKTdcC6E

1000W version test
https://www.youtube.com/watch?v=ksnf1ewgrAw

over load test (voltage drop when overload)
https://www.youtube.com/watch?v=-gEKRWsvgEs

over current protection test by shorting output (smps shutdown, non-latching)
https://www.youtube.com/watch?v=FSfd46yhywc

sinusoidal voltage at Cr
https://www.youtube.com/watch?v=y42T_Fw6fCs
 

Attachments

  • L6599 600VA.zip
    103.9 KB · Views: 87
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MicrosiM

Administrator
Staff member
@Res_SMPS


I would appreciate your help if you can give me transformer turns ratio for +-22VDC output & the TL431 regulator resistors values, I am facing some challenges


Thanks
 

res_smps

New member
Dear Microsim,

I tried to answer even though I myself was still learning
from the appplication note AN2450, the turn ratio is not the physical turn ratio n=N1/N2
but turn ratio n = 0.5 x Vdc(nom)/Vout
for 220V mains n = 220*1.4*0.5/22 = 7
is this what you mean?

tl431 part.jpg
for TL431 I honestly don't really understand too
for example I choose 1K2 for R1 ( I don't know what preferable value range)
vref = 2.5V
R2 = R1(Vout/vref-1)
for R1 I used fixed resistor+trimpot
Vout+-22V = 44V (from positif rail to negatif)
R1 = 1.2K(44/2.5-1) approx 19.92K

for R-C compensation I just tried from the example schematic, I have not understood

and make sure more than 1mA current passing trough TL431

I use the TL431 circuit like in page 6 from iraudps3
 

Attachments

  • iraudps3.pdf
    969.5 KB · Views: 57
  • AN2450 - LLC resonant half-bridge converter design guideline.pdf
    746.7 KB · Views: 49

res_smps

New member
l6599_1000w.jpeg slow progress
the schematic is similar to post no.1
using 4x1000uf 200V in capacitor just because I have in stock and for lower dimensions
totem pole transistor using a1020/c2655 instead of 8050/8550
more secondary capacitor
 

res_smps

New member
This project was delayed because it turns out that what I have is L6599 (without A) not L6599A.
L6599 has a feature to ensure the resonant tank does not work in capacitive mode via Isen pin.

I was confused because the chip always shutdown after starting until I found this document. View attachment Design Tip L6599.pdf
there is no difference in the L6599 and L6599A datasheet.

Finally I can make this smps work using the method as explained in the design tips
L6599.jpeg

The problem reappears when I try to activate the line sensing feature to detect DC voltage in the primary, the chip is always blown.
In the previous design this line sensing was connected to VCC via a voltage divider and could work.

So I decided to buy the L6599A before continuing.
 

MicrosiM

Administrator
Staff member
This project was delayed because it turns out that what I have is L6599 (without A) not L6599A.
L6599 has a feature to ensure the resonant tank does not work in capacitive mode via Isen pin.

I was confused because the chip always shutdown after starting until I found this document. View attachment 7012
there is no difference in the L6599 and L6599A datasheet.

Finally I can make this smps work using the method as explained in the design tips
View attachment 7014

The problem reappears when I try to activate the line sensing feature to detect DC voltage in the primary, the chip is always blown.
In the previous design this line sensing was connected to VCC via a voltage divider and could work.

So I decided to buy the L6599A before continuing.

I think that the design tip talking about two different ICs, L6599 & L6699 not L6599A or L6599

and that makes huge sense when you are using different chip.

Hope that helps.
 

res_smps

New member
I think that the design tip talking about two different ICs, L6599 & L6699 not L6599A or L6599

and that makes huge sense when you are using different chip.

Hope that helps.

aaaaagh .... thanks microsim, i just realized that this is l6699 not l6599, maybe i was too frustrated yesterday. 4 chip and 2 mosfet blown

but strangely this ebay chip (6599) can work when I treat it like the L6699 design tip
maybe next Saturday I'll try with the L6599A that was just received
 

MicrosiM

Administrator
Staff member
aaaaagh .... thanks microsim, i just realized that this is l6699 not l6599, maybe i was too frustrated yesterday. 4 chip and 2 mosfet blown

but strangely this ebay chip (6599) can work when I treat it like the L6699 design tip
maybe next Saturday I'll try with the L6599A that was just received


You need to pay attention to those Ebay chips.

But also you have to be aware that L6599A will NOT work if its not fully assembled, Trying to power it up from external power supply will be waste of time, and you will keep blowing chips.
L6599A can lead to multi failures if you dont understand how it works, an can be your worst design if you keep working that way.

Thanks
 

res_smps

New member
Thanks for the advice, fake chips are our main problem because most components are imported from china
Previously I also bought L6599A from a local shop that could not be used and the markings faded / disappeared when rubbed using cleaning liquid
 

res_smps

New member
I tried a new chip on a new pcb but it didn't work either.
finally I tried using the old pcb design and it could function well.
so it seems the problem is in pcb design.
I choose to be conservative, I will make a new pcb based on this old pcb with improvements:
- the addition of more secondary capacitors
- Improved EMI filter design

today I tried it on an amplifier
https://youtu.be/IxDuTM91zeM
I have a SMPS capable of 1000W, an amplifier capable of 250 to 400W.
but I only use it for less than 50W, hahaha ...

by the way I got this original chip at half the price of a fake one

chip2.jpgchip1.jpgtransistor driver.jpgold design.jpg
 

res_smps

New member
this is a new pcb design, using an old version of the controller module.
Tested using a transformer from the old design, unregulated at 90kHz frequency
new board.jpeg
 

res_smps

New member
Dear Silvio,

This is just the initial test to make sure its main function works.
I have not tried to load test, I expect to be able to get 1000W (with an additional fan if needed)

This pcb will be equipped with an extra +-15V regulated voltage (for preamps)
and +12/24V with mains voltage detection for speaker protector

l6599 silkscreen.jpg
 

Silvio

Member
Dear Silvio,

This is just the initial test to make sure its main function works.
I have not tried to load test, I expect to be able to get 1000W (with an additional fan if needed)

This pcb will be equipped with an extra +-15V regulated voltage (for preamps)
and +12/24V with mains voltage detection for speaker protector

View attachment 7034

That's more like it Res, I was saying to myself why the empty space? Well I am sure you will find a way to take the most of it. Everything that we build has its own experience but through knowledge and self taught we will succeed. That is the fun of home brew. Many a time it is not worth it as buying ready made will come far cheaper. I find every project that I make challenging and getting around all the difficulties that we find on the way makes us more wise and knowledgeable. If you come by any difficulties do not hesitate to share I will try the best I can to help out.

I will ask you for some help in the future when I come to a real resonant smps. I mostly build for the fun of it and nothing more.

Till then good luck

Regards Silvio
 

res_smps

New member
This is a photo after all the components are installed
some components use smd at the bottom layer
L6599 complete.jpeg
L6599 back.jpeg
output voltage :
+/-70V regulated (main output)
+/-12V
+12V

the next step is to load test
 

res_smps

New member
Load Test

Dear Silvio,
please check this video
https://youtu.be/ivXJcmac6Ww

I set the output voltage to +-60V (120V from positive to negative) because I only have a 15 ohm 200W dummy load,
I think +-70v is too high for testing
I dip the dummy load in a bucket of water to improve its power capabilities, but water also slightly decreases the resistance value

I want to test much longer but the circuit breaker in my house is trip because the capacity is only 1300VA

You can hear my children playing around me :)
 

Silvio

Member
Hi' Res i see you got a good result. From what I see you are loading around 1140w and input sees 1760w that is around 60% eff. This may not be true as bad power factor tend to draw more current than what really is drawn from smps. You need to see the actual watts at the input with a watt meter. Above all regulation seem to hold well with only a 2v drop. Well done Res.

I ask you some questions. How does the smps behaves with no load and full load regarding regulation? I guess you need a minimum load. When I added regulation to my smps it needed this as with no load the trafo was ticking meaning switching on and off. Even so from a peak voltage of 80-0-80v I had to set for 60-0-60 as there was not enough headroom for regulation higher than this. Voltage drop in the output inductor and other losses etc.

If the smps is intended for audio than do not trouble yourself much about holding full power for a long time. This week I was testing my 1000w amplifier and adjusted it at full blast with the clip indicator showing slightly at times. The average wattage was around 200-250w drawn by the amplifier smps at the input. You see although the smps can give more than a 1000w the average is somewhat quite smaller. During my bench tests when I was testing my smps (I have a cpu heatsink attached to my mosfets and diodes) It could hold 900w continuous without any problems with a very moderate temperature rise of around 50 degrees and held to that temperature for half an hour.
 
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