What are the limitations of stepper motor?

Answer 1

IntroductionA stepper motor is a brushless, synchronous electric motor that converts digital pulses into mechanical shaft rotation. Every revolution of the stepper motor is divided into a discrete number of steps, in many cases 200 steps, and the motor must be sent a separate pulse for each step. The stepper motor can only take one step at a time and each step is the same size.

Stepper Motor Advantages

1. The rotation angle of the motor is proportional to the input pulse.
2. The motor has full torque at standstill (if the windings are energized).
3. Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 to 5% of a step and this error is non-cumulative from one step to the next.
4. Excellent response to starting/stopping/reversing.
5. Very reliable since there are no contact brushes in the motor. Therefore the life of the step motor is simply dependant on the life of the bearing.
6. The stepper motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.
7. It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.
8. A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.

Stepper Motor Limitations

1. Resonance effects and relatively long settling

   times

2. Rough performance at low speed unless a

   microstep drive is used

3. Liability to undetected position loss as a result of

   operating open-loop

4. They consume current regardless of load

   conditions and therefore tend to run hot

5. Losses at speed are relatively high and can cause

   excessive heating, and they are frequently noisy

   (especially at high speeds).

6. They can exhibit lag-lead oscillation, which is

   difficult to damp. There is a limit to their available

   size, and positioning accuracy relies on the

   mechanics (e.g., ballscrew accuracy). Many of

   these drawbacks can be overcome