Voltage and Stepper motors, Thought and why

Part 2

Okay, having gone over part one and had some folks ask questions that have lead me to bring part two a bit forward in getting it out.

Folks have asked am I saying that that is maximum speed a steeper can go at a given voltage. No, I am not. What I am saying is that ACCURATE motion for the voltage is limited within that area. As you go beyond that speed (steps/sec) you are going to increase risk of error. Maximum speed is the equation below

Using this equations:

Max Speed=V2LImax⋅spr

Minimum Time per Step=2LImaxV

Pmax=ImaxV$$$$
$$$$

Where: V = Applied Voltage, L = the inductance of the motor, I_MAX = equals maximum current, and spr = Steps per revolution

Source for these equations is: HERE

Notice how once again voltage plays a major part in the equation. So we come around again to what is maximum and why voltage is important for stepper motor usage. The steps per second gives you a direct relation to the amount of accurate micro stepping you can do before inducing error.

So recapping from Part 1 and Part 2 we have this:

Stepper motors in most usages of CNC and 3D printing (AM) are open loop systems. Open loop systems need to operate near optimum function to insure accuracy and reduce possible induced error.

A stepper motor has a maximum Voltage where going beyond that voltage will start inducing damage to the motor unless actions are taken to deal with heat and EMF that will be an issue.

At or near that Voltage the motor will be able to have the largest torque curve available to it.

That torque curve dictates many diverse issues with the movement of the axis to include but not limited to smoothness of motion and accuracy of motion (protecting against loss steps) which also helps with the ratio of micro stepping.

Steps per second are directly effected by the amount of voltage available to the motor. which directly affects the amount of micro stepping that a motor can do accurately (not inducing error).

So stop for second and do the math, I would love to see more drives like the Bigfoot series that can handle 60V so that you can safely run 48V motors and insure no issues with EMF (though that is more a CNC issue than AM issue; it is still an issue.

Best Wishes and hope this helps