Reasons & Countermeasures for Stepper Motor Missing Steps

The stepper motor can realize the open-loop control of the position and speed of the motor according to the number of pulses and pulse frequency. It is a cheap, simple but easy-to-use controller motor, which has been more and more widely used in the field of automation control. However, because the stepper motor is not a closed-loop control, the wrong selection or improper use of the stepper motor can easily cause the stepper motor to lose step, that is, the stepper motor doesn’t reach the position it should reach according to the instruction, which makes engineers very distressed. Then, what is the reason for stepping motor out of step? What countermeasures can be taken to avoid losing step?

There are many reasons of the stepper motor losing step. In the actual application process, it is necessary to take the elimination method to analyze one by one to find out the real cause of out of step.Generally, there are several reasons below that cause stepper motors to lose step:

1. The DC stepping motor itself has insufficient working torque and is not capable enough to drive the load;

2. If the acceleration and deceleration process of the stepper motor is insufficient when it starts and stops, the stepper motor is prone to lose step in this process;

3. Insufficient power of the stepper motor causes the input power of the stepper motor to be too low and causes losing step.

4. The driving voltage of the stepper motor is not enough or the drive current is set too low;

5. The driver or controller receives signal interference;

6. Resonance of the stepper motor system causes the stepper motor’s load capacity to decrease and cause out of step;

7. The signal of driver and controller do not match;

8. The backlash error of the synchronous wheel or the gearbox is not compensated in the program or the compensation value is wrong;

9. There is a problem with the control program itself.

In view of the causes of the above problems, the following countermeasures can be taken to improve the stepping motor out of step problem:

1. Calculate the torque of the load, referring to the pitch chart of the stepper motor to observe whether the stepper motor at the corresponding speed has enough torque to drive the load. You can change to a stepper motor with a large torque at the corresponding working speed for a comparison test.

2. It is generally recommended that the moment of inertia of the load should not be larger than 10 times to that of the stepper motor, otherwise the acceleration and deceleration process will be relatively long.

3. At the moment when the stepper motor starts, we will test a current that is about 1.6 times to the rated current. If the power of the power supply is not enough, the effective current in the motor will be too low, which will not drive the load. It is generally recommended that the power supply has a margin of more than 30%.

4. The stepper motor needs to start quickly or run at high speed. It needs a relatively high drive voltage and a large enough working current setting value, otherwise it will easily miss steps.

5. Change to another model of the driver and observe whether its signal is disturbed, or control the movement of motor A and motor B to determine whether the motor signal is disturbed.

6. Choose a stepper motor with appropriate parameters to improve the performance of the drive or use physical methods such as shock absorbing pads to reduce vibration.

7. If the signals of the stepper motor driver and the controller do not match, the position offset will increase evenly over time. Just change the signal recognition method of the drive or controller to match the two.

8. Due to accuracy problems, there will be a certain accumulation of errors in the synchronous wheel or reduction gear box, and reasonable compensation must be made in the control program.

9. The control program can also cause the motor to lose step. It is necessary to check whether the control program has problems.

If the cause of the problem cannot be found for a while, the engineer will let the stepper motor run for a period of time to find the cause again, which will affect the efficiency of the equipment. In recent years, closed-loop stepper motors have become popular. It is also a solution through closed-loop control to realize complete control of stepper motors, but the cost will be higher. Now some drive chips of stepping motor can output a out-of-step signal of the stepping motor according to the abnormal change of the instantaneous current for the stepping motor out of step.

Defy produces different types of stepper motors and also provides customized services for customers. Welcome to visit our company for investigation and cooperation.

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