Basic Differences Between Stepper and Servo Motors
Stepper and servo motors differ in two key ways, in their basic construction and how they are controlled. Stepper motors have a large number of poles, magnetic pairs of north and south poles generated either by a permanent magnet or an electric current, typically 50 to 100 poles. In comparison, servo motors have very few poles, often 4 to 12 in total.
Driving a stepper motor to a precise position is much simpler than driving a servo motor. With a stepper motor, a single drive pulse will move the motor shaft one step, from one pole to the next. Since the step size of a given motor is fixed at a certain amount of rotation, moving to a precise position is simply a matter of sending the right number of pulses. In contrast servo motors read the difference between the current encoder position and the position they were commanded to and adjust the current required to move to the correct position. With today's digital electronics, stepper motors are much easier to control than servo motors.
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Stepper motors for sale offer several advantages over servo motors beyond the larger number of poles and easier drive control. The design of the stepper motor provides a constant holding torque without the need for the motor to be powered. The torque of a stepper motor at low speeds is greater than a servo motor of the same size. One of the biggest advantages of stepper motors is their relatively low cost and availability.
Servo Advantages
For applications where high speed and high torque is needed, servo motors shine. Stepper motors peak around speeds of 2,000 RPM, while servo motors are available many times faster. Servo motors also maintain their torque rating at high speed, up to 90% of the rated torque is available from a servo at high speed. Servo motors are also more efficient than stepper motors with efficiencies between 80-90%. A servo motor can supply roughly twice their rated torque for short periods, providing a well of capacity to draw from when needed. In addition, servo motors are quiet, available in AC and DC drive, and do not vibrate or suffer from resonance issues.
Stepper Limitations
For all of their advantages, stepper motors have a few limitations which can cause significant implementation and operation issues depending on your application. Stepper motors do not have any reserve power. In fact, hybrid stepper motors lose a significant amount of their torque as they approach their maximum driver speed. A loss of 80% of the rated torque at 90% of the maximum speed is typical.
Servo Limitations
Servo motors are capable of delivering more power than stepper motors but do require much more complex drive circuitry and positional feedback for accurate positioning. Servo motors are also much more expensive than stepper motors and are often harder to find.
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http://q-eng.com/diary/22137
Driving a stepper motor to a precise position is much simpler than driving a servo motor. With a stepper motor, a single drive pulse will move the motor shaft one step, from one pole to the next. Since the step size of a given motor is fixed at a certain amount of rotation, moving to a precise position is simply a matter of sending the right number of pulses. In contrast servo motors read the difference between the current encoder position and the position they were commanded to and adjust the current required to move to the correct position. With today's digital electronics, stepper motors are much easier to control than servo motors.
Stepper motors for sale offer several advantages over servo motors beyond the larger number of poles and easier drive control. The design of the stepper motor provides a constant holding torque without the need for the motor to be powered. The torque of a stepper motor at low speeds is greater than a servo motor of the same size. One of the biggest advantages of stepper motors is their relatively low cost and availability.
Servo Advantages
For applications where high speed and high torque is needed, servo motors shine. Stepper motors peak around speeds of 2,000 RPM, while servo motors are available many times faster. Servo motors also maintain their torque rating at high speed, up to 90% of the rated torque is available from a servo at high speed. Servo motors are also more efficient than stepper motors with efficiencies between 80-90%. A servo motor can supply roughly twice their rated torque for short periods, providing a well of capacity to draw from when needed. In addition, servo motors are quiet, available in AC and DC drive, and do not vibrate or suffer from resonance issues.
Stepper Limitations
For all of their advantages, stepper motors have a few limitations which can cause significant implementation and operation issues depending on your application. Stepper motors do not have any reserve power. In fact, hybrid stepper motors lose a significant amount of their torque as they approach their maximum driver speed. A loss of 80% of the rated torque at 90% of the maximum speed is typical.
Servo Limitations
Servo motors are capable of delivering more power than stepper motors but do require much more complex drive circuitry and positional feedback for accurate positioning. Servo motors are also much more expensive than stepper motors and are often harder to find.
https://meiyinang43.share-art.jp/
http://q-eng.com/diary/22137
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