[Moved] UC3825 Controller Problem when used with a Buck converter

[haseebakhtarhussain]

i'am making a MPPT tracker using a buck converter and UC3825 as a PWM controller, the PSIM model and hardware implementation is attached.


The main problem is that uc3825 is not generating PWM , pin1 (INV) and pin2 (NI) are used to make a type 3 compensator, whenever voltage changes on these pins the duty cycle of generated PWM on the output pins is supposed to change, but in my case there is absolutely no PWM single,

my system is working on 100kHZ and required duty cycle is above 80%, i appreciate your help in advance.

 

[BradtheRad]

Did you try making the power source unchanging DC? Does it work properly then?

The reason for this question: A PV panel is not a stable power source. High V, low A.
Low V, high A.

You installed an input capacitor. I believe an input inductor is needed, between the PV panel and input capacitor. That arrangement should allow you to draw continual smooth 4A from the panel.

 

[haseebakhtarhussain]

actually i'm testing all of this system with stable DC power supplies (non_changing).
and i'm also testing UC3825 independently applying 0-3V DC supply on compensatory pins (PIN1 & 2) and trying to change the voltage levels by hand

 

[Velkarn]

i think it is not allowed to connect outa and outb pins

 

[haseebakhtarhussain]

I've tried them both separately, the result was even worst..