Why does the stepper motor easily lose step at the moment of starting?

 

Torque Limitations:

Stepper motors operate based on the principle of sequential energization of electromagnetic coils, resulting in discrete steps. However, stepper motors have a limited torque output at higher speeds, which can lead to step losses during startup. As the motor accelerates from a standstill, the torque required to overcome inertia and move the load increases. If the applied torque exceeds the motor's capability, steps can be lost, causing a loss of synchronization. It is crucial to select a stepper motor with sufficient torque rating for the application and ensure that the motor is not overloaded during startup.

 

 

 

 

 

 

 

 

Picture from: 17HS13-0404S1

 

 

 

 

 

 

 

 

 

Resonance Effects:

Resonance occurs when the natural frequency of the motor coincides with the excitation frequency, leading to excessive vibrations and decreased motor performance. During startup, the stepper motor may encounter resonance frequencies that cause oscillations and result in step losses. Resonance can occur due to mechanical factors such as coupling stiffness, system compliance, or improper load inertia matching. To mitigate resonance effects, it is important to analyze the system dynamics, identify resonance frequencies, and implement measures such as adding damping or adjusting the system's natural frequency.

 

 

 

 

 

Picture from: 17HS08-1004S

 

 

 

 

 

 

 

 

 

 

Insufficient Current Control:

Accurate current control is essential for the proper operation of stepper motors. During startup, if the current supplied to the motor coils is insufficient, the motor may not generate enough torque to overcome the load inertia, leading to step losses. Inadequate current control can be caused by factors such as improper driver settings, incorrect current limit settings, or insufficient power supply capability. Ensuring that the stepper motor driver is properly configured and that the current limit is set appropriately for the motor's requirements can help minimize step losses during startup.

 

Backlash and Mechanical Considerations:

Backlash, which refers to the mechanical play or clearance in the drivetrain components, can contribute to step losses during startup. Backlash in the mechanical system can cause a delay in motion when the motor changes direction or tries to overcome initial resistance. This delay can result in lost steps and affect the motor's synchronization. Minimizing or compensating for backlash through proper mechanical design, such as using backlash compensation techniques or employing anti-backlash mechanisms, can help mitigate step losses during startup.

 

Microstepping and Resolution:

Microstepping, a technique that divides each full step into smaller microsteps, can improve the resolution and smoothness of stepper motor motion. However, it can also increase the likelihood of step losses during startup. Microstepping can reduce the available torque per microstep, making it more challenging for the motor to overcome inertia and start smoothly. Increasing the current limit, adjusting the microstepping ratio, or using higher-resolution stepper motors can help address this issue and reduce step losses during startup.