Patent ID: 7218074

Claim:
Method for limiting the current output by a speed controller (V) for electric motor (M), said controller (V) comprising an inverter of PWM type whose electronic switches are commanded by a microcontroller circuit (Mc) and operating according to a control law (LC) of U/F type according to which the voltage (Vqref) applied to the terminals of the stator is proportional to the frequency of the stator (Wstat) in accordance with a determined constant (k), said method being characterized in that it consists in: comparing the modulus of the vector of the measured phase currents (ModI) of the motor (M) with a limit value (Ilim) so as to obtain a limitation error, if the modulus of the vector of the phase currents (ModI) is greater than the limit value (Ilim), calculating a correction voltage (dV) as a function of said limitation error, calculating the product of the correction voltage (dV) with the inverse of said determined constant (k), subtracting the product thus calculated from the frequency of the stator (Wstat) so as to obtain a corrected frequency of the stator (Wstatc), according to the voltage control law (LC) of U/F type, calculating the product of the corrected frequency of the stator (Wstatc) with said determined constant (k) to obtain the control voltage (Vqref) applied to the motor (M).