Patent ID: 7959414

Claim:
A control system for protection against break of the lubricating-oil film in bearings of compressors comprising: an electric motor of M phases ( 20 ) associated to the compressor ( 21 ), forming a motor-compressor assembly ( 20 , 21 ), the compressor ( 21 ) having a bearing, the bearing being covered with a lubricating film; a microprocessor ( 10 ), an inverter ( 2 ) comprising a set of switches (SW 2M ), the inverter ( 2 ) being connected to a voltage (V BARR ), and associated to the microprocessor ( 10 ), the inverter ( 2 ) modulating the voltage (V BARR ) to feed the motor ( 20 ), a voltage observer ( 30 ) measuring the level of voltage at the output of the inverter ( 2 ) and a current observer ( 40 ) measuring the current that circulates through the set of switches (SW 2M ) of the inverter ( 2 ), associated to the microprocessor ( 10 ), wherein the microprocessor ( 10 ) actuates the set of switches (SW 2M ) selectively, so as to generate a rotation on the motor-compressor assembly ( 20 , 21 ), the compressor ( 21 ) having a minimum rotation speed (RPMmin) of the compressor ( 21 ) so that the oil film will not break, the microprocessor ( 10 ) being configured for, on the basis of the information from the voltage observer ( 30 ) and/or from the current observer ( 40 ), establishing a bearing-situation variable, said bearing-situation variable having a predetermined maximum value, the microprocessor ( 10 ) raising the rotation speed of the motor ( 20 ) to a value higher than the minimum rotation speed (RPMmin) according to a pre-established relationship of the bearing-situation variable to prevent the breakage of the oil film in the bearing.