Drive / Current Sizing

Stepper holding torque vs current, microstep derating, servo Kt/Ke.

Holding torque (N.m)

Rated current (A)

Drive current (A)

Steps per revolution

Microstep setting

Torque constant Kt (N.m/A)

Back-EMF Ke (V/(rad/s))

Required torque (N.m)

Microstep derating : T_ms = Th · (2N/π)·sin(π/(2N))
Current torque     : T_cur = Th · (I_drive / I_rated)
Servo current      : I = T_req / Kt

Microstep torque is derated vs full-step holding torque.