Comparison of conducted RFI emission from different unity power factor AC/DC converters

Low frequency harmonics injection into AC power supply and small power factor are the main disadvantages of conventional AC/DC converters. By using current mode control, the converter can be designed such that its input current have a sinusoidal form and in phase with the power supply voltage. By solving the problem of power factor with high frequency switching current mode control, another problem arises; that of high frequency harmonics generated in radiofrequency (RF) range by the power converter. In this paper, an AC/DC power converter with fixed topology (diode bridge+boost converter) is used and various current control methods are applied to it. After simulating the converter behavior and also using the simulation of a standard network; "line impedance stabilization network", (LISN), placed between the AC power supply and the converter, the conducted RF noise is computed. Finally, laboratory experimental results were compared with simulation results.