# Stepper Motor Maximum Speed and Power Calculator

Stepper motors are normally used for positioning, and are not known for their speed. This calculator computes the maximum speed of a stepper motor, which is limited by the time it takes for the coil to energize to it's maximum holding current, and then de-energize as polarity flips.

Input:
Imax (A)
L (mH)
Voltage (V)
Steps/Revolution Steps
Result:
Maximum Speed (revolutions/sec)
Minimum Time/Step (milliseconds)
Maximum Power (Watts)

### Equations:

Current through the coil is proportional to the time that the voltage has been applied, and inversely proportional to the inductance.

I= V*T/L

T= I*L/V

For one step the current must go from 0 to Imax and back to 0, or alternatively from -Imax to +Imax.

I= 2*Imax

T= L*Imax*2/V

T is the number of seconds for a single step.

To compute maximum revolutions per second - divide seconds per step by steps per revolution.

Rev/sec = V/(L*2*Imax)/(steps/rev)

Pmax= 2*Imax*V

Pmax occurs not when the motor is going max speed because the current is a triangle wave. Pmax occurs when the slope of the current is small compared to the on holding time of the step pulse.

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