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How Do You Calculate the RPM of a Stepper Motor?

Published in Electronics 2 mins read

You calculate the RPM of a stepper motor by considering its steps per revolution (SPR), pulses per second (PPS), and the motor's holding torque.

Understanding the Key Factors

  • Steps per Revolution (SPR): This indicates how many steps the motor takes to complete a full rotation. It's a fixed value determined by the motor's design.
  • Pulses per Second (PPS): This represents the frequency of pulses sent to the motor driver, dictating the motor's speed.
  • Holding Torque: This refers to the motor's ability to resist external forces while stationary. It's crucial for maintaining position accuracy.

Formula for Calculating RPM

The formula for calculating RPM is:

*RPM = (PPS / SPR) 60**

Where:

  • RPM is the revolutions per minute.
  • PPS is the pulses per second.
  • SPR is the steps per revolution.
  • 60 is the conversion factor from seconds to minutes.

Practical Example

Let's assume a stepper motor has 200 steps per revolution (SPR = 200) and is receiving 500 pulses per second (PPS = 500). Using the formula, we can calculate the RPM:

*RPM = (500 / 200) 60 = 150 RPM**

This means the motor is rotating at 150 revolutions per minute.

Important Considerations

  • Motor Driver: The motor driver controls the pulses sent to the motor, affecting its speed.
  • Microstepping: Some drivers use microstepping, which increases the number of steps per revolution, potentially leading to smoother operation.
  • Load: The load on the motor can affect its speed and efficiency.
  • Holding Torque: Ensure the motor's holding torque is sufficient for the application to prevent position slippage.

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