Proteus showing wrong Output (SMPS converter)

[syedfarisjalali]

I was trying to make a circuit of DC Voltage booster

It showa a maximum current of 400 milli amp going through the collector of bd136 while in reality it should have gone to Killo Amperes considering that inductor series resistance in proteus is just 0.00002 ohms

 

[KlausST]

Hi,

The kiloamperes is not reality, it is your expectation.

I didn't go through all the circuit...but the current is not limited only by the resistance of the inductance...

I assume here it is limited by the h_FE of the BD136.

Klaus

 

[syedfarisjalali]

in this i am giving a 100% duty cycle pwm to the base of bc547 which further drives bd136 just to check the max current going through the transistore while in reality before this i had made the same setup with 10% duty pwm 100 hz frequency throug a microcontroller and built the circuit practically... the average current which the multimeter show me flowing through the collector and emitter of bd136 was 3.6 amp and it blew off within i guess around 10 secs ... i was worried about it coz proteus had given me a green flag by showing a peak current of 800 mili amps through the collector of bd136

 

[KlausST]

Hi,

H_FE varies a lot from real part to part.
And the current surely is a function of voltage - this information I can't find in your post.

Whether a device burns or not is rather a fuction of dissipated power than of the current alone. To calculate the power you additionally need the voltage V_CE.

The same transistor can be killed by 0.1A but can withstand continously 1A ... A question of V_CE.

Klaus

 

[syedfarisjalali]

voltage coming in through the top left is 12 volts. since there is an pnp transistor linked to the inductor and the base of bd136 always gets a negative voltage with resp. to the emitter of bd136 it will always stay in on mode... and it did in reality ... it would have burned then and there but somehow there was some current limiting factor from the input which didnt let the current increase more than 3.5 amps so it lasted for 10 secs otherwise acc to datasheet the max. collector current is 1.5 amps but with proteus it show just 400 milli amps and thats a very big disadvantage as i would like it to be real... u have any of software which would give actual results