Question

Calculate the output voltage of the Buck-Boost converter if the supply voltage is 78 V and duty cycle value is .1.

(a) 7.2 V

(b) 4.5 V

(c) 8.6 V

(d) 5.1 V

I have been asked this question in a national level competition.

Question is taken from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives

Answer 1

Right choice is (c) 8.6 V

Explanation: The output voltage of the buck-boost converter is Vo = D×Vin ÷ (1-D)=.1(78)÷.9=8.6 V. It can step up and step down the voltage depending upon the value of the duty cycle. If the value of the duty cycle is less than .5 it will work as a buck converter and for duty cycle greater than .5 it will work as a boost converter.