Abstract
Switched-mode power supplies (SMPSs) are a relevant and widespread source of unsymmetrical conducted emissions, as they feed various electrical appliances and information technology equipment in office and residential contexts and, despite their low power rating, the limits are the same as those of larger equipment. Given the peculiar emission waveform (mixing impulsive components and switching components), assessment should be carried out with care to select parameters that guarantee both the detection of the maximum level of emissions and a high level of repeatability and reproducibility. A range of cases based on six different SMPS products was considered, exploring both time- and frequency-domain characteristics, and identifying the most relevant phenomena and advisable parameters choices. Typical behavior and suitable settings were exemplified with a range of measured emission records: the Fourier time window length and EMI receiver dwell time were considered, as well as the relevance of loading conditions to include in a comprehensive test program. Such records were made available in a linked dataset to allow for replication of the experiments and foster further findings and discussion.
Highlights
Academic Editors: Gianpaolo VitaleSwitched-mode power supplies (SMPSs) are extensively used to supply a wide range of items of information technology, entertainment and audio products, electrical appliances and telecommunications
They are deployed in large numbers within residential and light industrial environments, connected to the low voltage (LV) mains: with their low power rating, they have received little attention so far, but their large number hints that their emission characteristics should be considered in more detail
SMPSs feature various power conversion architectures but share common elements that make their input waveforms look quite similar, distinguishing them from high-frequency content: the front-end input stage is based on a simple single-phase rectifier, providing an internal DC-link voltage characterized by a ripple at twice the mains frequency; the conversion process is based on a two-leg converter, feeding the high-frequency transformer with an almost symmetrical waveform, swinging between the two extremes of the DC-link voltage and, exhibiting alternate polarity of the pattern of emissions
Summary
Switched-mode power supplies (SMPSs) are extensively used to supply a wide range of items of information technology, entertainment and audio products, electrical appliances and telecommunications They are deployed in large numbers within residential and light industrial environments, connected to the low voltage (LV) mains: with their low power rating, they have received little attention so far, but their large number hints that their emission characteristics should be considered in more detail. SMPSs may feature different modulation patterns implemented in different onboard regulator technologies so that the behavior may be quite different in principle, it is sensible that a broad division into some main classes is attainable This work addresses this problem of classifying the behavior of SMPSs as far as conducted emissions are concerned in order to derive general rules for signal processing methods. The considered frequency range between 2 kHz and 1 MHz was characterized by supraharmonic disturbance and radiofrequency (RF) components, with a wide range of different behaviors that well represent the mechanisms of emissions
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