Variable-speed scroll refrigeration compressor

A variable-speed scroll refrigeration compressor, comprising:

• a sealed enclosure containing a compression stage,
• an oil sump housed in a lower portion of the sealed enclosure,
• an electric motor having a stator and a rotor,
• an oil pump rotationally coupled to the rotor of the electric motor, the oil pump comprising an oil inlet port connected to the oil sump of the compressor and at least one first oil output port, and
• control means arranged to control the operation of the electric motor according to at least one start-up mode in which the rotor of the electric motor is rotated at a first speed of rotation comprised in a first speed range, and a normal operating mode in which the rotor is rotated at a second speed of rotation comprised in a second speed range, the second speed range being higher than the first speed range,
• the compressor comprises an oil injection device including at least one oil injection duct connected to the first oil outlet port of the oil pump and arranged to supply the compression stage of the compressor with oil, and the control means include monitoring means arranged to vary a value that is representative of an output torque of the electric motor so as to keep the first speed of rotation substantially constant during the start-up mode, the control means being arranged to control the operation of the electric motor in the start-up mode until the value representative of the output torque becomes lower than a predetermined value.