provide a rotor speed signal Spd_feedback relating to the actual speed of the rotor, based on the two current values ia(t) and ( ί ) and the signals Ua(t)and ( ί ). The sensor-less speed/flux position observer stage 28 is further configured to provide an angle 'estimated indicative of the rotor angle estimated, based on the two current values ia(t) and ( ί ). In an exemplary embodiment, the sensor-less speed/flux position observer stage 28 may comprise a rotor angular position estimator and rotor angular speed estimator. The rotor angular position estimator may be configured to determine the angular position 'estimated of the rotor based on the two current values ia(t) and ( ί ) without using a position sensor, whereas the rotor angular speed estimator may be configured to determine the rotor speed Spd_feedback based on the angular position 'estimated. The Park transform stage 27 is configured to: receive the angle 'estimated and the measured current values i and in the two-phase , Park-coordinate system (stationary reference frame) and convert the current values ia(t) and ( ί ) to a two- phase d-q coordinate system (rotating-synchronous reference frame), generating the measured synchronous currents id(t) and iq(t) based on the angle 'estimated. In the exemplary embodiment, the subtractor stage 20 is configured to receive in input a motor speed signal Spd_ref and the motor speed Spd_feedback. The motor speed signal Speed-ref relates to a reference motor speed associated to a command signal indicating the requested motor speed, whereas the motor speed signal Spd_feedback relates to the determined motor speed provided by the sensor-less speed/flux position observer stage 28. The subtractor stage 20 is configured to determine a speed error based on the difference between input motor speed signals Spd_ref and Spd_feedback. The speed control stage 2 1 is configured to receive the speed error and provide the current iqref. For example, the speed control stage 2 1 may comprise a PI controller and is configured to operate in the two-phase d-q coordinate system. The current iqref is indicative of the reference rotor current in the q-axis of the d-q coordinate system. The signals Spd_ref and Spd_feedback , iqref and idref can be, in general, time-varying signals, whose explicit time dependence is not illustrated in the notation to improve