The term Current Shaping (CS) describes a special circuit design. CS influences the true phase current curve to correspond to the given nominal curve over a wide frequency range.
If a stepper motor is operated without special current shaping measures, deviations between the TRUE and NOMINAL current curves are found even at relatively low frequencies. These deviations are caused by the motor inductance and back-electromotive force (generator) feedback in the stepper motor that increases with speed.
These deformations of the nominal curve are subject to strong fluctuations during a motor revolution and the motor is prone to natural resonance oscillations, which can sometimes cause loss of position, acoustic noise or the stalling of the motor.