Question

A step down chopper is operated at 240V at duty cycle of 75%. Find the value of RMS switch (IGBT/MOSFET) current. Take R = 10 Ω.

(a) 2.07 A

(b) 200 mA

(c) 1.58 A

(d) 2.4 A

I had been asked this question in an interview for internship.

Question is taken from Choppers-3 topic in division Choppers of Power Electronics

Answer 1

Right option is (a) 2.07 A

Best explanation: The switch could be anything, a IGBT, a SCR, a GTO etc. The current through the switch is the same as the current through the load for a step down chopper.

Vo = Vs/1-α

α = 0.75

I = √α x Vs/R.