What best describes a servo motor and its drive?

• A. A servo motor is a precision motor with feedback; a servo drive controls position, speed, and torque using feedback
• B. A servo motor is a generic motor; a servo drive only controls speed
• C. A servo motor is a stepper motor; servo drive handles torque only
• D. A servo motor is an AC motor; servo drive controls frequency only

Answer: (A)

Closed-loop feedback is what defines a servo system. A servo motor is a precision device chosen for accurate motion, and it works with a servo drive that uses feedback to control the motor. The motor usually has an encoder (or similar sensor) that reports its actual position and speed. The drive compares this feedback to the commanded target and continuously adjusts the motor current to minimize the error. That feedback loop lets the system accurately reach and hold a position, follow a speed profile, and limit or apply torque as needed, even when loads or disturbances change.

Because of this feedback-enabled control, the drive can operate in multiple modes: moving to a specific position, maintaining a set speed, or delivering a commanded torque. This combination of precise motion and multi-mode closed-loop control is what sets a servo motor and its drive apart from simpler or open-loop motor setups.

Other descriptions don’t capture that continuous feedback and multi-faceted control. A generic motor implies no built-in feedback; a stepper motor is a different technology often used in open-loop systems; a drive that handles only speed or only torque misses the full capability of position, speed, and torque control provided by a servo system.