A servo drive controls motor torque, speed, and position using a high-speed feedback loop. It receives a command from a controller, powers the motor, measures actual motion, and continuously corrects the difference.
The four main elements
- Motion controller: creates the position, speed, or torque command.
- Servo drive: converts the command into controlled motor current and voltage.
- Servo motor: produces mechanical motion.
- Feedback device: reports position, speed, and motor information.
How the loop works
The controller requests motion. The drive compares the request with encoder or resolver feedback, calculates the error, and adjusts current to reduce it. This cycle repeats rapidly, allowing accurate response to changing load and speed.
Control modes
Torque mode regulates motor force, speed mode regulates velocity, and position mode regulates movement to a target. Many systems use nested current, speed, and position loops.
Why matching matters
The drive must support the motor voltage, current, feedback protocol, commutation, brake, thermal sensor, and firmware generation. Cables, option modules, safety functions, and controller communication must also be compatible.
Before troubleshooting or replacing
Record alarms, back up parameters, capture full motor and drive part numbers, and inspect cables and connectors. Send US² Automation these details with the machine function, quantity, and delivery location.