This paper explores the level of conducted EMI in a buck boost converter under a non linear load condition based on the CISPR 11 / Class A EMC standard. Here, the buck boost converter was designed to produce a constant output voltage irrespective of load conditions. The closed loop control is designed using dsPIC controller. Three different randomization firing schemes are adopted and the EMI analysis in each mode is done experimentally. Also, the results are compared with normal PWM scheme. The experimental result shows that in RPWM scheme the emission levels are comparatively low.
