In AC-VFDs, voltage is primarily used to control which aspect of the motor?

In AC Variable Frequency Drives (AC-VFDs), voltage is primarily used to control the torque of the motor. The fundamental principle behind AC-VFDs involves altering the voltage and frequency supplied to the motor to achieve the desired performance. By adjusting the voltage, the VFD can effectively manage the magnetic field within the motor, which directly impacts how much torque is produced.

When the voltage is increased, the motor can generate more torque, particularly under load, as it can create a stronger magnetic field. This capability allows fine control over the motor’s performance characteristics, making torque management essential in applications where precise control is needed.

While speed can also be influenced by changing frequency, which the VFD primarily manages, voltage adjustments play a critical role in establishing the torque levels—particularly at lower speeds. Therefore, understanding how voltage impacts torque is crucial for optimal motor and drive performance in various industrial applications.

Choices like direction and efficiency are important but are not primarily controlled by voltage in the same direct manner. The direction of the motor is controlled by phasing of the voltages, and efficiency is generally a byproduct of the motor's design and operational parameters rather than a direct result of voltage changes.