Question

Calculate the phase voltage for 3-∅ 120° VSI if the value of DC supply is 26 V.

(a) 10.52 V

(b) 10.97 V

(c) 10.96 V

(d) 10.61 V

The question was asked during a job interview.

This intriguing question originated from Solid-State Switching Circuits topic in chapter Introduction to Solid-State Switching Circuits of Electric Drives

Answer 1

The correct answer is (d) 10.61 V

To explain I would say: The line voltage for 3-∅ 120° VSI is (VDC÷√6)=10.61 V. In 3-phase 120° VSI each phase conducts for 120° and only three switches from different phases conduct at a single time.