A method for controlling an electric motor by using the PWM technique; the control method includes the steps of: applying to the clamps of the electric motor an electric voltage varying in time, which displays a square waveform and consists of a sequence of pulses having a uniform wave period and a variable amplitude; adjusting the average value of the electric voltage applied to the clamps of the electric motor by varying the amplitude of the pulses of the electric voltage; determining, in the case of a variation of the amplitude of the pulses, the overall required amplitude variation; subdividing the overall required amplitude variation in a determined number of partial variations, the overall sum of which is equivalent to the overall required amplitude variation; and gradually varying the amplitude of the pulses of the electric voltage by applying in a sequence a corresponding partial variation to each pulse, so that the difference between the amplitude of a pulse and the amplitude of a following pulse is equivalent to the corresponding partial variation.