current ia(t)”(estimated from available and motor phase-currents and commanded duty- cycle signals to the inverter), and the voltage Vdc(t) of the DC-link capacitor 11 to determine the current correction values iqcorr(t) and idcorr(t) to be used to modify the current references iqref and idref that current regulator system 14 uses to control the electric motor 2. Control method performed by the active voltage limiter unit 15 controls the voltage Vdc(t) of the DC-link capacitor 11 in order to “clamp” the voltage Vdc(t) to a constant value in case, for example, the electric motor 2 tends to regenerate back- current (ip(t) becomes negative) to the DC-link capacitor 10 (i.e. during breaking of the motor). The situation of negative DC-link current ip(t)<0 can be detected through the computation of the said active current ia(t), that surrogates the unavailable current ip(t). Consequently, the method controls iqrefmod and idrefmod in order to limit the negative active current ia(t) till bringing it to zero if necessary (to completely cancel any back-current to the capacitor). It will be disclosed hereinafter the meaning of the active current ia(t) used by the control method. Tests performed by Applicant proved that the dynamic of the DC- link capacitor 11 evolves according to the following equation: d/dx Vdc (t) = (ir (t) — ip t / Cdc When the input stage 4 is a passive uncontrolled rectifier, then the current ir(t) > 0 (current that flows from the rectifier to the DC-link capacitor) is uncontrollable (and fluctuates at twice the mains frequency) and, for the small capacitance of the DC- link capacitor 11, when ir(t) by chance approaches zero, even a small negative ip(t) (regeneration current occurring in braking operation) may cause a large voltage overshoot. This situation may harm the electronic components of the motor controller stage 6, which may fail due to overvoltage. In this respect, the control method uses the active current ia(t), which is obtained by combining the measurements of the phase currents with the duty cycle commands, to detect the regeneration (i.e., the occurrence of back-currents). Indeed