What is the primary function of a variable frequency drive (VFD) in motor control?

The primary function of a variable frequency drive (VFD) is to control the speed and torque of an electric motor by varying the frequency and voltage supplied to the motor. By adjusting the frequency of the AC power, a VFD allows for precise control over the motor's rotational speed, which can lead to enhanced energy efficiency and improved process control in various applications. This capability makes VFDs especially useful in applications where varying speeds are required, such as fans, pumps, and conveyor systems, enabling operators to optimize performance and respond to changing load conditions effectively.

The other options refer to functions that are not the main purpose of a VFD. For example, while a VFD does manage voltage as part of its operation, it primarily focuses on frequency modulation to achieve speed control. Converting DC power to AC power is the role of a different device known as an inverter, not a VFD. Additionally, while VFDs can facilitate the control of multiple motors, their primary function is not solely to synchronize them but rather to modulate the speed and torque as required by operational demands.