Abstract: Inverters are widely used in modern industrial production fields, but it is very sensitive to voltage sags. It often causes the speed to fall below the lower limit due to voltage sags, resulting in equipment jump and greater economic losses. Based on this,a weak excitation current control is proposed to reduce the excitation current reference value to maintain the high level of speed operation and avoid the oversaturation of DC terminal voltage. Secondly, an improved power reference value calculator is proposed to introduce the speed reference value into the active power calculation to maintain it at a high level, and to introduce the excitation current reference value into the reactive power calculation to reduce it actively, so as to avoid the speed falling below the lower limit and causing the equipment to trip-stop. Finally, a simulation model is constructed on the MATLAB/Simulink platform, and the effectiveness and applicability of the proposed method in improving the voltage dips tolerance ability are verified through the analysis of examples.