Question about Buck-Boost chopper

buck boost chopper

hi all,

now i would like to build a buck-boost chopper which have variable output.
after i done my connection as shown in the figure, i found that 0V at my output..
no matter how i adjust the frequency fed in, the output is still 0V.

then i go to do some researches, i found that almost all the buck-boost chopper is done my using chips. One of my senior told me that this is because the inductor in basic connection of buck-boost chopper couldn't charged up the capacitor for the inductor current tends to go to ground of function generator. the basic connection can only be used when the ground of function generator separate from the -ve terminal of my input voltage.

my question is:

1)is my senior's comment right?
2)is the basic connection of buck boost chopper not practical to build?

hope u all can teach me...

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buck-boost chopper

What 's you simulation tool and setting ?

matter on buck chopper

The problem is when the switch is supposed to be in the off-state. The emitter is supposed to go negative, but the base can only go from 0V to Vin, so you won't be able to turn the BJT off. It would make more sense to use a PMOS or pnp as the power transistor. Alternatively, the pwm control can be referenced from the common connection between the switch, diode, and inductor. Your pwm control circuit would need to be able to withstand high voltages, though.

buck chopper

hi
my friend the buck boost is practical, and i think the prioplem is that your switch is not working or the drive circuit is not capaple of switching it as required

plus consider increasing the value of your inductor, and if yoou didnt simulate youre circuit on a pc then its time for it .


best regards

control circuit for buck chopper

ur uploaded picture is right ! I guess whether the parameter of component is rightly choosed, such as indutor,capacitor,diode,etc. How many is ur load current ? Pls check!