Effect of voltage sags on digitally controlled line connected switched-mode power supplies

Different voltage disorders like voltage fluctuations, sags, frequency variations may occur in the power supply networks due to different fault conditions. These deviations from normal operation affects in different ways the line connected devices. Standards were developed to protect and ensure immunity to these voltage deviations. In the following paper an analysis of different grid disturbances is presented. Some limitations and immunity requirements based on standards for devices connected to low voltage grid are described. The behavior of digitally controlled boost PFC converter in case of voltage sags is analyzed. Fault tolerant control algorithm was designed, implemented and is discussed. The fault conditions and their effects were investigated at different power levels.