Monitoring device of rotor position of an electric motor and corresponding method

摘要

A monitoring device for an electric motor has in input a signal representing zero crossings of the back-electromotive force of the motor and comprises a monitor that detects the signal in first periods of time arranged around instants of time in which the zero crossings are expected. The device comprises a setting circuit that sets second periods of time that are less than the first periods of time and each second period of time is centered on the instant of time in which the zero crossing is expected. The monitor comprises a detector that tests whether each actual zero crossing occurs inside the second period of time and a controller that modifies by a quantity the subsequent period of electric revolution time between two consecutive expected instants of zero crossing if said actual zero crossing occurs outside the second period of time.