Question

In the below given figure the converter 1 (to the right side) has firing angle = α1, converter 2 has firing angle = α2. For the dual converter to operate in the second quadrant.

(a) α1 > 90°

(b) α2 > 90°

(c) α1 < 90°

(d) α2 < 90°

The question was asked in class test.

This intriguing question comes from Dual Converters-3 topic in portion Converters of Power Electronics

Answer 1

Correct option is (b) α2 > 90°

The best explanation: Converter 1 would control the first and the fourth quadrant and converter 2 would operate in the second and the third quadrant. In the second quadrant, voltage should be positive and current should be negative, hence inverter operation hence α2 > 90°.