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GATE 2017 EE – Question 35

Power Electronics · Single-phase and three-phase voltage and current source inverters, sinusoidal pulse width modulation · 1 mark · Numerical answer

A 3-phase voltage source inverter is supplied from a 600 V DC source as shown in the figure below. For a star connected resistive load of 20 $\Omega$ per phase, the load power for 120° device conduction, in kW, is ________.

A three-leg bridge of IGBTs with anti-parallel diodes, fed from a 600 V DC source. The load is three $20\ \Omega$ resistors connected in star.

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Show answer and explanation

Correct answer: 8.5 to 9.5

Explanation

With 120° conduction, two of the three phases conduct at any instant, and the two resistors are in series across the 600 V supply. The current is $\frac{600}{2 \times 20} = 15$ A. The power is $15^2 \times 40 = 9000$ W, which is 9 kW.