SENSORLESS SAFETY SYSTEM FOR DETERMINING ROTATION OF AN ELECTRIC HOUSEHOLD APPLIANCE LAUNDRY DRUM POWERED BY A THREE-PHASE ASYNCHRONOUS MOTOR

摘要

An electric household appliance (1) having a casing (2); a laundry drum (3) mounted inside the casing (2) to rotate about an axis of rotation; a three-phase asynchronous motor (6) for rotating the laundry drum (3); and a sensorless safety system (7) for determining rotation of the rotor (32), to determine rotation or no rotation of the laundry drum (3). The sensorless safety system (7) is designed to supply three direct currents (las, lbs, Ics) to the three stator power phases (31) during a predetermined time interval (?T), so as to magnetize the rotor (32); to cut off supply of the direct currents (las, lbs, Ics); to determine the time pattern of at least one of the three induced currents (Iar, Ibr, Icr) induced in the stator (30) in response to magnetizing the rotor (32); and to determine rotation or no rotation of the rotor (32) on the basis of the time pattern of at least one of the three induced currents (Iar, Ibr, Icr).