# What is the limiting factor for the maximum speed of stepper motors?

• liquidFuzz
In summary, during a discussion about stepper motors, it was mentioned that the coils in the motor have a limit to how fast they can be fully saturated with current. This time can be calculated using Kirchhoff's and Lentz's law. The calculated theoretical speed is significantly higher than the speed listed in data sheets for standard stepper motors. When accelerating or decelerating at speeds above the rated maximum step rate, the stepper motor may miss steps. This is due to the peak magnetic field only being needed for full torque and the current saturation time in the coils being limited by factors such as power requirements and electrical efficiency.
liquidFuzz
I was discussing stepper motors with a friend. We touched upon different aspects. I showed how the coils in the motor have a limit to how fast they can be fully saturated with current, and how this time can be calculated by the aid of Kirchhoff's and Lentz's law. The theoretical speed calculated is significantly higher than the speed listed in data sheets for standard stepper motors.

Is there anyone here that know what is limiting the speed for stepper motors?

liquidFuzz said:
Is there anyone here that know what is limiting the speed for stepper motors?
It depends on how much power you require.
The peak magnetic field is only needed for full torque.
It is probable that the stepper will miss steps when accelerating or decelerating at speeds higher than the rated maximum step rate.

According to my estimate, or approximation might be a better way of describing it, the current saturation time in the coils is:##t = - \frac{L} {R} \ln \left( \frac{U-iR}{U} \right) ##As seen in the model I only consider the electrical behavior of the circuit, i.e a coil L and a resistor R in series. The reactance of the coil might affect the efficiency but probably not account for the difference between this kind of model and the specs in data sheets.

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## 1. What is a stepper motor's maximum speed?

A stepper motor's maximum speed is the fastest rotational speed that the motor can achieve without losing steps or stalling. This speed is typically measured in revolutions per minute (RPM) or steps per second.

## 2. How is a stepper motor's maximum speed determined?

The maximum speed of a stepper motor is determined by several factors, including the motor's design, the number of steps per revolution, the supply voltage, and the load on the motor. Other factors, such as the quality of the motor's control system and the type of driver used, can also affect the maximum speed.

## 3. Can a stepper motor's maximum speed be increased?

Yes, a stepper motor's maximum speed can be increased by using a higher voltage power supply, optimizing the motor's control system, and reducing the load on the motor. However, increasing the maximum speed may also decrease the motor's torque and precision.

## 4. What happens if a stepper motor exceeds its maximum speed?

If a stepper motor exceeds its maximum speed, it may lose steps, causing the motor to skip or stall. This can result in inaccurate positioning or even damage to the motor. It is important to always operate a stepper motor within its maximum speed limits.

## 5. How do I calculate a stepper motor's maximum speed?

The maximum speed of a stepper motor can be calculated by dividing the motor's step angle (in degrees) by the number of steps per revolution and multiplying by the motor's maximum RPM. For example, if a motor has a step angle of 1.8 degrees, 200 steps per revolution, and a maximum RPM of 6000, the maximum speed would be 60 RPM (1.8/200 x 6000).

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