Patent ID: 6265891
Filing Date: 2001-07-24
Classification: H02H

Abstract:
An apparatus for detecting a coil short-circuit in an electric motor comprising:a rotor angular position detecting sensor for detecting an angular position of a rotor;a plurality of phase coils provided on a stator;a plurality of current sensors which sense currents flowing in the respective phase coils;an energizing controller calculating an energizing initiating rotor angle, a de-energizing terminating rotor angle, and a reference current amount for each of the phase coils on the basis of a target revolutions per minute (RPM) and torque of the motor,the energizing controller initiating an energization of each of the phase coils when the angular position of the rotor which is detected by the rotor angular position sensor is found to be in coincidence with a respective energizing terminating rotor angle for each phase coil,the energizing controller terminating the energization of each of the phase coils when the angular position of the rotor which is detected by the rotor angular position sensor is found to be in coincidence with a respective de-energizing initiating rotor angle for each phase coil,the energizing controller making a comparison between the current amount sensed by each of the current sensors and the reference current amount during a time duration between the initiation and the termination of the energization of the phase coil, for continuing and interrupting the energization of the phase coil if the sensed current amount is less and not less, respectively, than the reference current amount;set-up time measuring means for counting a set-up time duration which ranges from a time point at which the sensed current amount is zero to another time point at which the sensed current amount reaches the reference current amount;calculating means for calculating a references set-up time duration, based on the reference current amount;decision means for deciding whether or not a short-circuit occurs in each of the phase coils based on a comparison between the set-up time duration measured by the set-up time measuring means and the reference set-up time duration.