Application of Random PWM Technique for Reducing EMI
Journal Title: International Research Journal of Applied and Basic Sciences - Year 2013, Vol 6, Issue 9
Abstract
A pulsewidth modulation (PWM)-controlled active filter generates harmonics at the switching frequency and its multiples in the RF range, and the concentrated power spectrum may produce electromagnetic interference (EMI) problems. In this paper, the random PWM (RPWM) technique is applied in orderto spread the noise spectrum over a wide range, thus, considerably reducing the amplitudes of these harmonics and the consequent EMI problems. To study the operation of active filters, the case of an ac/dc converter along with a power-factor corrector is considered as a nonlinear load and a series active filter, respectively.A line impedance stabilization network is used to study the RF noise emanating fromthe converter. A noise model to study the EMI emission is presented and used in this paper. Theoretical analysis of the RF noise power spectrum is carried out in orderto demonstrate the advantages of the RPWM technique over conventional PWM. Experimental results confirm the validity of the theoretical calculations and simulation results, and demonstrate the effectiveness of applying the RPWM technique in reducing the RF noise level.
Authors and Affiliations
Abdolreza Esmaeli| Plasma Physics and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, Tehran, Iran., Zahra Kohshari| Faculty of Electrical Engineering, MaziarUniversity, Nour, Iran, email: aesmaeli@aeoi.org.ir
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