The Reason of the Loss of Step of Stepper Motor

The stepper motor is an open-loop control motor that converts an electric pulse signal into angular displacement or linear displacement. When out of step not occurs, the speed of the motor, the stop position is determined by the frequency of the pulse signal, and the number of pulses is not affected by the change of load. When the stepper motor receives a pulse signal, the stepper motor will rotate a certain angle. By controlling the number of pulses and the frequency of the pulse, the number of angular displacement and motor speed can be controlled. Also, there exists a certain error between the rotated angle and the theoretical step angle. However, the stepper motor has the same number of steps per rotation. And the step distance error will not accumulate for a long time.

The factor of fall out of step:

1. Rotor acceleration is slower than the rotating fields of the stepper motor.

2. The average speed of the rotor is higher than that of the stator magnetic field.

3. High load inertia of the motor.

4. The stepper motor generates resonance.

The rotor accelerates slowly, the torque generated can not make the speed of the rotor reach up to the rotary speed of stator fields, which will cause fall out of step.

When the speed of the rotor is lower than phase changing speed, the motor will lose a step. This is because the average speed of the electric energy of the motor is higher than the average speed of the stator field. This is because the stator energizing time is longer than the required time for stepping. In the stepping process, the rotor achieves too much energy, which causes that the torque of the motor is too large and contributes to the loss of step.

The reason why the stepper motor loses step is the inappropriate stepper driver. Only selecting a suitable step driver can give full play to the advantages of accurate control. Choosing a suitable driver should be based on the current of the motor, which should be equal or larger than the current. If the low vibration or low precision is required, a subdivision driver can be used.

For large torque motor, high voltage driver should be used to achieve the performance of high speed. At the same time, for drivers current, many people will use switch power supply as a drive supply. However, it is best not to use a switching power supply, especially a large torque motor. Because, the motor work is a large inductive type of load, which will form a high voltage to the power end.

The reason why the stepper motor generates resonance is that the pulse frequency received by the motor is equal to the inherent frequency of the stepper motor, which is related to the subdivision of the driver. Commonly, when we use a stepper motor, the performance of the subdivision of the driver is very important. The smaller the resonance range, the better. The large load inertia of the motor is due to motor overload.