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  • Reduced conductive EMI in switched-mode DC-DC power converters without EMI filters: PWM versus randomized PWM
    Mihalič, Franc, elektrotehnik ; Kos, Dejan, 1978-
    This paper addresses improved electromagnetic compatibility (EMC) in switched-mode power converters (SMPCs), without using electromagnetic interference (EMI) filters. A practical solution is proposed ... for minimizing conductive EMI in a pulsewidth modulated (PWM), and random PWM dc-dc power converters. A comparative investigation is performed into the use of differentrandom modulation schemes (driven by the DSP-2 board with the TMS320C32) as against the normal PWM. The effectiveness of randomization on spreading those dominating frequencies that normally exist in constant frequency PWM schemes is evaluated by power spectral density (PSD) estimations in the low-frequency range. Some parasitical- and topology-based EMI sources in devices are presented and frequency analysis is shown by using the discrete Fourier transform (DFT). SPICE simulations are also used to verify practical solutions for eliminating negative EMI sources and achieving EMC improvements. Finally, levels of conductive EMI are estimated with DFT, and experimentally verified to comply with the CISPR 25 (or EN 55025) regulations. Moreover, it is clearly shown, that limited speed PWM driving of the power switches with appropriate snubber circuits guarantees reduced conductive EMI. When considering the price and high EMC, in the final solutionthe power converter is driven by the u-controller PIC16F876 with limited numerical and peripheral capabilities, where only normal PWM and randomized PWM can be implemented.
    Source: IEEE transactions on power electronics. - ISSN 0885-8993 (Vol. 21, no. 6, nov. 2006, str. 1783-1794)
    Type of material - article, component part ; adult, serious
    Publish date - 2006
    Language - english
    COBISS.SI-ID - 10874390

source: IEEE transactions on power electronics. - ISSN 0885-8993 (Vol. 21, no. 6, nov. 2006, str. 1783-1794)

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