Glossary · Motion control and drives
Servo motor
Also known as: Servomotor, AC servo motor
German: Servomotor
In motion control, a servo motor is a motor designed for closed-loop position, velocity or torque control, typically a permanent-magnet synchronous motor with an integrated encoder, low inertia and high overload capacity, operated by a servo drive.
- Motion control
In one sentence
A servo motor is built for closed-loop control: usually a PMSM with integrated encoder, low inertia and high overload capacity.
Example
The filling machine's dosing pumps are driven by servo motors with holding brakes and multiturn absolute encoders.
How it applies
- Engineering: Servo motors are sized by continuous stall torque, peak torque, speed and inertia ratio to the load. Options include holding brakes, encoder types and single-cable technology.
- Commissioning: Electronic nameplates let the drive read motor data automatically.
- Maintenance: Holding brakes need periodic testing; they are designed to hold a stationary load, not as service brakes to stop a moving axis, except for emergencies within the manufacturer's limits.
- Documentation: For vertical axes, explain brake test procedures and the danger of gravity-loaded axes falling when the brake is released or fails. Warn about hot motor surfaces (Thermal hazard).
Servo motor vs. stepper motor
A servo motor always runs in closed loop with feedback. A Stepper motor usually runs in open loop by counting steps and can lose steps under overload.