An algorithm for prediction of the DC link voltage of the VFD during voltage sags

The problem of the stability of a frequency-controlled drive in the conditions of voltage failures is topical, since modern production is sensitive to process disturbances. Of particular interest are the issues of preserving the parameters of the drive and the drive mechanism without the use of additional drives and converters. However, these methods of passing through voltage sags require accurate and rapid determination of the DC link voltage parameters for power grid voltage deviations. The article presents a method that allows, in less than half a period of the supply voltage, to determine both the shape of the DC bus voltage of a frequency-controlled drive and the value of its individual parameters (maximum instantaneous value and constant component). The accuracy of the proposed method for voltage failures of various kinds is determined in comparison with simulation results in the Simulink MATLAB.