I am trying to make a boost converter using uc3843 with the following

- the input voltage = 12v
- the input current = 4A
- the output i want = range 150v to 235v
- the current output = 0.5A

i will use mosfet irf840 and diode UF4007

did did my design according to texas instrument pdf for boost converter
https://www.ti.com/lit/an/slva372d/slva372d.pdf



calculated :

- max duty cycle = 1- (V in min / V out max)* η
i assumed η = 80%

- I switch = I coil = I diode = ΔI/2 + I out max/ 1- D
(ΔI/2 = I load min = 10% of the I max = 0.05A)

inductor (L) = V in * (V out max - V in min) / ΔI*Fs*V out)
Fs = 100 KHz
ΔI = 2* I load min

i add R7 to the schematic just to make the circuit CCM boost converter ( i am not sure about its value yet!)

what do you think about this boost converter will work?

 

Hi Momen,
Have you tried this design in LTSpice and got the results?

Please post your LTS asc file.

E

 

Hi Momen,
Have you tried this design in LTSpice and got the results?

Please post your LTS asc file.

E

not yet, actually i am new to ltspice i will see some tutorial for sitmulating it

 

R8 and C5 are connected to the wrong place.
Should be between comp and feedback.

 

R8 and C5 are connected to the wrong place.
Should be between comp and feedback.

just update the schematic

 

A boost converter with that boost ratio will be impractical and difficult to control. A typical design would be limited to a boost ratio of 5-6 and you are far in excess of that.

On top of that your input power is:

12V * 4A = 48 Watts

Output power is:

150V @ 0.5 A = 75 Watts

If you can make this happen, you will win a Nobel prize.

I'm going to hazard a guess and say this will NOT be happening.

 

A boost converter with that boost ratio will be impractical and difficult to control. A typical design would be limited to a boost ratio of 5-6 and you are far in excess of that.

On top of that your input power is:

12V * 4A = 48 Watts

Output power is:

150V @ 0.5 A = 75 Watts

If you can make this happen, you will win a Nobel prize.

I'm going to hazard a guess and say this will NOT be happening.

You are right, i do not know how i ignored this!!
I will try to increase the input to 24v - 5A

 

Now you have R4 connected to the wrong place. Should go to 0V

 

Now you have R4 connected to the wrong place. Should go to 0V

i think its non sense to add R8, the purpose of R2-R3 is to create 2.5v (voltage divider), should i remove R8?

 

i think its non sense to add R8, the purpose of R2-R3 is to create 2.5v (voltage divider), should i remove R8?
View attachment 304706

R8 sets the maximum gain of the error amplifier.

 

Also, your gate resistor of 100 ohm is way too high. The Mosfet will switch slowly.

 

R8 sets the maximum gain of the error amplifier.

if i changed there position here will this work?

 

Also, your gate resistor of 100 ohm is way too high. The Mosfet will switch slowly.

after i increase the voltage to 24v i think 240mA to the gate is good, what do you think