salil_desai
Newbie level 4
i'm trying to simulate a solar charger(not in software but in actual hardware) using a DC power supply to charge a battery of 12V/7AH..for that i hav built the following BOOST circuit:
Vout = 13.8V
Iout = 0.75A
Fs = 50Khz
L = 600uH (pot core) continuous conduction mode
Cout = 100uF
Rload = 33 ohm/ 15W resistor
i'm using the voltage mode control IC 3525 to generate the PWM
and IRF540 mosfet for switching with and RCD snubber of R=10K C=270pf D=MUR860
my diode in series with the inductor is MUR860 with an RC snubber of R=20K and C=130pF
the PWM starts at approx 8.5VDC and gives a max duty of 0.45 which is enough according to my calculations..
*BOOST ACTION ACHIEVED*
NOW,from my sampling network(potential divider) i start a feed back.
my feedback is a type 3 compensation in which there is a series resistance R1= 122ohm with the inverting terminal(pin1 of 3525) of error amplifier. the NI terminal(pin2 of 3525) of E.A is given a fixed 2.5V reference..now from the o/p of E.A to the invrtng i/p of the same E.A is a series RC with R2= 193K and C1 = 330pF and a C = 22pf in parallel with this RC
NOW while testing this hardware:
NO LOAD CONDITION: i adjusted the o/p voltage Vout to 13.8V
LOAD CONDITION: as soon as i give my resistor load the o/p drops down to 12.6 and has a ripple of almost 1V...the inductor makes a hissing sound..and a current as high as 45A flows thru the load
please help me out here..i want stable 13.8VDC and my MAX current should be 0.75 A ..i think my feedback is not properly compensating
Vout = 13.8V
Iout = 0.75A
Fs = 50Khz
L = 600uH (pot core) continuous conduction mode
Cout = 100uF
Rload = 33 ohm/ 15W resistor
i'm using the voltage mode control IC 3525 to generate the PWM
and IRF540 mosfet for switching with and RCD snubber of R=10K C=270pf D=MUR860
my diode in series with the inductor is MUR860 with an RC snubber of R=20K and C=130pF
the PWM starts at approx 8.5VDC and gives a max duty of 0.45 which is enough according to my calculations..
*BOOST ACTION ACHIEVED*
NOW,from my sampling network(potential divider) i start a feed back.
my feedback is a type 3 compensation in which there is a series resistance R1= 122ohm with the inverting terminal(pin1 of 3525) of error amplifier. the NI terminal(pin2 of 3525) of E.A is given a fixed 2.5V reference..now from the o/p of E.A to the invrtng i/p of the same E.A is a series RC with R2= 193K and C1 = 330pF and a C = 22pf in parallel with this RC
NOW while testing this hardware:
NO LOAD CONDITION: i adjusted the o/p voltage Vout to 13.8V
LOAD CONDITION: as soon as i give my resistor load the o/p drops down to 12.6 and has a ripple of almost 1V...the inductor makes a hissing sound..and a current as high as 45A flows thru the load
please help me out here..i want stable 13.8VDC and my MAX current should be 0.75 A ..i think my feedback is not properly compensating
Attachments

1.6 MB Views: 90
Last edited: