A method of controlling a compressor (1) is described, particularly a method that prevents the piston (5) from knocking against the valve system (8, 9) provided therein. The present invention has the objective of controlling the stroke of the piston (5) of a linear compressor (1), allowing the piston (5) to advance as far as the end of its mechanical stroke in extreme conditions of load, without allowing the piston (5) to collide with the valve system (8, 9). This objective is achieved by means of a method of controlling a compressor (1), particularly a linear compressor, which comprises a piston (5), and a linear motor (2), the piston (5) moving along a stroke and being driven by the motor (2), an average voltage (Vm) being applied to the motor (2) and controlling the movement of the piston (5), the method comprising the steps of measuring a first time of movement of the piston (5), comparing the first time with a foreseen time of movement, altering the voltage (Vm) if the first movement time is different from the foreseen movement time, the foreseen movement time being such that the movement of the piston (5) will reach a maximum point (M), the point (M) being substantially close to the end of the piston stroke. A system for monitoring the position of a piston (5) of a linear compressor (1), as well as a compressor (1) are also foreseen. |