Question

A step-up chopper is used to feed a load of 400V d.c from a 250V d.c source.The induction current is continuous if the off time of the switch in 20 mu s .The switching frequency of the chopper in KHz is​

Answer 1

Answer:below is answer

Explanation:

Vo = 400 V

Vs = 250 V

Toff = 20 μsec

F = ?

Vo =  

Vs

1 - D

∴ 1 - D =  

Vs

1 - D

1 - D =  

250

400

Now Toff = (1 – D) T

∴ T =  

Toff

=  

20 × 10-6

× 400

1 - D 250

Now f =  

1

=  

250 × 106

T 20 × 400

∴ f = 31.25 kHz