boost converter with Proteus 8

[Johnnie42]

I have designed a boost converter with Proteus but it doesn't work. As you can see in the picture the output voltage is only 15V. But I have calculated that my output voltage should be 90V.
My PWM-Signal for the nmosfet is 50kHz with 50% duty cycle with 12V.

Does anyone know why the circuit isn't working?

 

[FvM]

Can you tell what's the purpose of R8 and why it limits the output voltage to about 15 V even if the transistor isn't switching at all?

Secondly, what are the parameters of "NMOSFET"? Did you check if it's on-resistance is low enough for correct circuit operation?

Finally, did you examine the circuit waveforms, e.g. gate and drain of NMOSFET before posting at Edaboard?

 

[Johnnie42]

sry the circuit i post was not the right one, but I still have the same problem, the output voltage is to low.

I test this circuit in reality and it works but in the simulation it doesn't.

I also think that the NMOSFET is the problem, maybe he isn't switching or something like this, but I didn't find out why. I try some different NMOSFETS but still the same problem.

 

[FvM]

I also think that the NMOSFET is the problem, maybe he isn't switching or something like this, but I didn't find out why. I try some different NMOSFETS but still the same problem.

Here the suggestion about checking waveforms comes into effect. You know there's an oscilloscope in Proteus?

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I really don't know if a gate driver component without supply voltage terminals can have a reasonable output signal. That's something you should find out.

 

[Allen6502]

The Vdd and Gnd of the TC4427 are connected to default of 5V. Change it to 12V and you'll be able to get the 90V output that you have expected.

Use /Design/Config power rail/VCC_VDD and set it to 12V.

Allen