Question

Speed of 3-$\phi$ synchronous motor can be controlled by varying frequency at constant torque at

• A. Variable voltage and constant current
• B. Variable voltage and variable current
• C. Constant voltage and constant current
• D. Constant voltage and variable current

Hint:

In V/f control, voltage is adjusted to maintain torque when frequency changes.

Answer 1

The Correct Option is A

To maintain constant torque, the voltage-to-frequency ratio (V/f) must remain constant. At constant torque, current should remain unchanged.