Waveform Modeling of Conducted Disturbances Below 150 kHz from Power Conversion Equipment

Abstract

Power conversion equipment (PCE) such as a rectifier, which uses pulse width modulation (PWM) and/or pulse frequency modulation (PFM), is known to generate conducted disturbances over broad frequency bands, including 150 kHz. To clarify the effect of the conducted disturbances below 150 kHz on ICT equipment, conducted immunity evaluation with test waves of a continuous wave (CW) or a CW with pulse modulation are specified in the International Electrotechnical Commission (IEC) standards. However, it is not clear that those test waves can simulate the features of conducted disturbances from a PCE with PWM/PFM control well enough to evaluate the conducted immunity characteristics of ICT equipment in an actual usage environment. To achieve such an evaluation, authors have considered the effect of PWM/PFM on conducted disturbances, and found that both disturbance peak amplitude and frequency fluctuated when PWM/PFM control was operated. In this paper, authors propose numerical expressions for conducted disturbances below 150 kHz from PCE, applying a formula for amplitude modulation (AM) to express the temporal fluctuation of peak amplitude, and a formula for frequency modulation (FM) to express the temporal fluctuation of peak frequency. We also discuss the creation of a waveform model using the proposed numerical expression, and its validation in a conducted immunity evaluation of a power line communication (PLC) system. The immunity evaluation indicated that the proposed model can evaluate the conducted immunity characteristics in an actual usage environment more accurately than using the conventional waves, CW or CW with pulse modulation.