UCC25600: Simulation, hardware & system design tools forum

Hello,

Your inquiry is under review and we will get back to you shortly.

Regards,

Hello,

I would check your voltage amplifier output to see what it is doing?  This will let you know if the feedback loop is working correctly.

If the feedback loop is working correctly and the output is not in regulation then your transformer turns ratio might be off. 

If you loop is working find and your transformer turns ratio is O.K.  the issue might with over current projection preventing regulation.

Regards,

here is the output voltage of error amp(pink color waveform )

At 1ohm load resistance output voltage droops to 19v

Hello,

Your inquiry is under review and I will get back to you shortly.

Regards,

Hello,

Your output divider on your op amp is set to control the output at 23.3 V.  If you want a 24 V output I would adjust that to achieve 24 V.

In your waveform if you output is 19 V your voltage amplifier output should be railed high.  It looks like the amplifier output is 3.4 V even though the output is not in regulation.  I would double check your voltage amplifier setup vs the schematic just to check that it is connected as you expect.

Regards,

Here is the schematic diagram of feedback loop

if i adjust feedback loop the error amp output is increases, but no change to converter output stil it is in 19v at 1ohm output resistance

Hello,

Your inquiry has been received and is under review.

Regards,

Hello,

I studied this some more.  If the COMP pin is 3.4 V diode D15 should be back biased.  This means the design should be operating at the min frequency maximum gain.  This means any or of the following could be wrong.

1. Your transformer turns ratio is incorrect.

2. Your Lm to Lr raio is not correct.

3. Your minimum frequency is not set correctly by RT.

There is an excel design tool at the following link that you can use to check your design to see what may need to be adjusted 1..3.

https://www.ti.com/tool/UCC25600-DESIGN-CALC

Regards,

Hi,

With the given link i couldn't download the design calculator

there is no download option 

Hello,

Sorry about that.

There is a copy of the excel tool in the following e2e thread.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1259755/ucc25600-design-calc-calculation-tool-is-not-available-to-download

Regards,

Hi, 

I have simulated this circuit as per the value given in the design calculator, but still it is not regulating

Hello,

If you used the design tool then design should be O.K.  The issue could be with your simulation.

Look at the voltages across Lr, Lm and and Cr and see if they are what you expect them to be verses frequency?

One other thing you might want to check is to make sure your minimum programmed frequency is set above the capacitance region.  If it is not you gain may be decreasing when it should be increasing.

Regards,