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error amplifier problem with uc3525

sebastian thomas66
Prodigy 65 points

Dear all,   

I am facing some error amplifier problem with UC3525

I am trying to design an a Automatic Voltage Regulator for regulating the output of 230volt AC Generator. 

REGULATIG METHOD (Synchronized half bridge) --- input voltage regulation by applying the output dc voltage feedback to the excitation coil of the AC generator)

AVR input voltage----230 volt AC from the AC generator

AVR output voltage ----8 to 15v feed back to generator excitation coil

output current of the converter---- 3A

               Please help me solve the error amplifier problem of sg3525 .I’m using UC3525 with ir2010

Sync -buck converter design.

Input voltage of the converter-340Vdc,

Required output voltage -8 to 15 V dc

Reference voltage at pin 2of sg3525 -2.5v from reference pin

Feedback voltage at pin 1---2.5 to 2.7vDC, for testing purpose can feed this voltage from the voltage divider out of auxiliary 12v power supply with common ground

Converter is working well by this configuration.

But my problem is when I apply the same 2.5 to 2.7vDC taken from the 340vDC input with voltage divider  (From the rectified and filtered input of the AVR  -because we want to regulate the input voltage of the AVR) this time the AVR  output is very high about 180volt

Compensation resistor value used 20K

Can you please suggest any solution to rectify this problem?

What at is the relation between Compensation resistor value and the feedback voltage of uc3525?

 

  • 0
    TI__Genius 14570 points

    Hello,

    To answer your question, can I clarify what you want to do?

    Do you want to regulate 8-15Vout from rectified 350VDC? I think you need take 8-15V and divide down to 2.5V, which is the reference voltage. Without feeding Vout, you can't get and regulate 8-15V.

    Regards,
    Sean