the signal can be computed by synchronous-frame currents and signals Ud(t) and Uq(t). Moreover, the following linear relation holds: Equation (10) Therefore, Applicant has found that controlling the active current ia(t), in view of Equation (10), is equivalent to controlling ip(t). In particular, zeroing ia(t) corresponds to nullifying ip(t). In case harmful regeneration is detected (negative ia(t) or increasing capacitor voltage Vdc(t)) then, as a first provision, it is possible to stop the regeneration current by nullifying ia(t). Besides ia(t), it is possible to use another synthetic signal, named iaref(t), that gives an anticipation (forecast) on what will be the value of the active current ia(t) after the current regulators have settled. Indeed, in a motor drive with current-regulators (for id(t) and iq(t)), the currents are commanded to prescribed values idref and iqref, and the regulators are in charge of obtaining the required currents by computing suitable duty cycles, to be actuated by the inverter unit. For a prescribed pair of reference currents, it is defined the-reference-active current-at-time-t, the signal computed with the reference currents and the duty cycles at time t: Equation (11 ) For a change in the reference currents (commanded in turn by a speed/torque controller or by a flux/weakening or magnetization block), the signal iaref(t) gives coarse forecast about what will be the active current after the transitory, since the current regulators will drive the currents toward the references. Flow chart of Figure 4 contains the operations performed by the active voltage limiter unit 15 to modify the current references of the current regulator system 14 in