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# CAn anybody help me in designing this

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#### rahimi

##### Newbie level 3
hello, can anybody here help me in designing a boost converter circuit using pspice. i have already design it but unfortunely the outcome is not the same as predicted.
the requirement are to produce an output voltage of 24 V across a 15 load resistor. The output voltage ripple must not exceed 0.5 %. The dc supply is 8 to 16 V. here i attached the circuit that i have build and i'm using pspice version 8.
the frequency that i used is 50kHz in the calculation to get L and C. if can, please give any suggestion to correct the circuit.thanks.

Hi,

Well to have a 120mV of ripple, you just need to change the value of the C for C = Io*dT/dV = 133.33uF, where Io = 24V/15ohms = 1.6A, dV = 24V*0.05% = 120mV, and dT is given by d*T, where d is calculated from the transfer function d = 1 - Vi/Vo = 0.5, and T = 1/F = 20us, so dT = d*T = 10us.

One thing that can cause your simulation to fail is the 1N4007 diode, you need a fast transistor and fast recovery diode, check my attachment, I think is very easy to understand and calculate the L and C.

And finally you can just play with the Vi or d so you can get exactly 24V in the output.

Regards

narccizzo

narccizzo, thanks for the circuit that u give to me. however i cant implement it since several part that u use are not listed in my pspice. can you give me a suggestion where can i get the part of D1 MUR3020PT,MPS3904 and MPS3906. or can this part be replace by other component?

Hi, well I used that circuit because if is implemented physically you need a circuit to drive the mosfet gate properly, but for simulation purposes you can connect directly the square signal directly to the mosfet input, and respect with the mur diode you can use any, you just make sure in its datasheet that is a fast recovery diode, try the 1n4148 (just for simulation) is a very common and the 2sb649 or b649 and 2sd669 or d669 instead the mps transistors.
If you decide to implement the circuit physically, you can use any fast recovery diode just make sure the continuous forward supported current is at least twice the maximum simulated.

Regards,

narccizzo

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