1. System for limitation of the output current from a speed controller for three-phase asynchronous electric motors, comprising a PWM type converter in which the electronic switches are controlled by a microcontroller circuit (Mc), characterized by the fact that the microcontroller circuit comprises means (LIC) of calculating the modulus of the current vector from current measurements in the motor phases, and comparing it with a limitation set value in order to obtain a limitation error (y), and means of calculating the correction voltage (&Dgr;V) that is added to the control voltage (V) applied to the motor.