In a constant $V/f$ control of induction motor, the ratio $V/f$ is maintained constant from $0$ to base frequency, where $V$ is the voltage applied to the motor at fundamental frequency $f$. Which of the following statements relating to low frequency operation of the motor is $TRUE?$
- At low frequency, the stator flux increases from its rated value.
- At low frequency, the stator flux decreases from its rated value.
- At low frequency, the motor saturates.
- At low frequency, the stator flux remains unchanged at its rated value.