Do you really need a servo? Can an induction motor with a feedback device provide a better solution for specific applications? Looking at definitions and performance characteristics for servos and induction motors may move the decision along.
Servo motor system: A servo is not just a motor. It is a closed loop motion system composed of a controller, a drive, a motor and a feedback device, usually an optical or magnetic encoder. The confusion begins when the motor supplier advertises a servo motor.
The “servo motor” is a synchronous machine with permanent magnets (PM) that is represented by a brush or brushless PM motor. It has certain performance characteristics that separate it from other motor types. The permanent magnet synchronous motor possesses very high peak and continuous torques used to drive the servo system at high acceleration and deceleration rates in precision positioning systems. Torque is directly proportional to input current. Motor shaft speed is directly linked to input voltage. The higher the input voltage, the higher the motor’s speed. Torque versus speed curve is linear.
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- Wilfried
