Study of conducted susceptibility of power converters

The most widely used offline switched mode power supplies (SMPS) are prone to conducted noise, despite line filters and other protection circuitry at their front-end. They are exposed to LV power line transients which are one of the most dangerous types of conducted noise. These transients can be either differential mode (DM) type or common mode (CM) type. The CM line transients can cause malfunctioning of SMPS during its normal working and hence cause disturbance in its output voltage. One of the types of malfunctioning of SMPS because of CM transient is studied here. Three types offline SMPS namely forward, flyback and half-bridge of same output ratings are considered. Simulation results, experimental results and a method to eliminate such malfunctioning are presented.