There are two reasons for this:
1. The control pulse frequency is high, so the acceleration of the rotor is less than the speed of the stator rotating magnetic field of the stepper motor.
The stepper motor power supply design, the stator coil electric time constant is basic fixed, assumes that the time constant is 0.02 S (0.02 S charging to a maximum of 63%), if the stepper motor to accept pulse cycle is greater than 0.04 S (duty ratio is 50%, the frequency is less than 25 hz), of the stator coil which can gain enough energy to produce enough to drive the rotor torque. If the pulse frequency is too high, such as 50 hz (duty ratio is 50%, more than 0.02 S) pulse cycle, the stator coil for the charging time of just 0.01 S, about half of charging time, the torque is reduced a lot, the rotor can't keep up with the speed of the stator rotating magnetic field, each step behind the equilibrium position should be arrived, and farther and farther away from the equilibrium position. The cumulative result is loss of pace.
Of course, the frequency of 50HZ is too small, this example is just for the convenience of illustration, a number of solutions are given at will: 1, reduce the pulse frequency, don't think trouble, debugging stepper motor is mostly to adjust the pulse frequency process
2. If you do not want to reduce the frequency and cause the speed to be too low, then increase the power supply current of the stepping motor
3. Reduce the load of the motor
Second, the control pulse frequency is low, the speed of the rotor is higher than the speed of the stepper motor stator rotating magnetic field.
Are above the 0.02 S, for example, charging time constant pulse frequency is low, the stator coil charging fully, its produce torque is big, if the motor load lighter, will more than should be in the balance of rotor position, stator rotor magnetic field and to pull back to the equilibrium position, when the same back to the equilibrium position and the across the equilibrium position and equilibrium position behind, just under a pulse arrives at this time, so the rotor in the equilibrium position behind the place to start a new step. This cycle also causes each step to fall further and further behind the equilibrium position it should have reached. The cumulative result is loss of pace.
Solution: 1. Increase the pulse frequency
2, do not want to be too high speed, then reduce the stepping motor supply current.
3. Neither of the above two can be adjusted, so change the motor with small torque.