Which method is commonly used to adjust the torque of an AC motor?

Adjusting the torque of an AC motor is commonly achieved by altering the frequency applied to the motor. The speed and torque characteristics of an AC motor are fundamentally linked to the frequency of the electrical supply. When the frequency is increased, the motor speed increases, and thus the torque can be adjusted depending on the motor's design and the load conditions. This method is particularly prevalent in variable frequency drives (VFDs), which allow for precise control over the motor's performance by varying the frequency and voltage supplied to the motor.

Increasing the voltage can influence the performance of the motor, but it mainly affects the torque's ability to overcome load rather than providing a direct method for torque adjustment. Changing the load type can also impact motor performance but does not directly adjust the torque settings of the motor. Modulating the power supply pertains to controlling or adjusting how power is delivered but doesn't necessarily correlate to a specific method of adjusting torque in a consistent manner like frequency adjustment does.