A method to reduce Electromagnetic Interference (EMI) of multiple switching waveforms by harmonic cancellation is presented. The waveforms considered are input currents generated by 'n' Discontinuous Mode (DCM) Flyback Switched Mode Power Supplies (SMPS) that share a common source. The waveforms are modeled as ideal triangular waveforms and a Fourier analysis is performed to determine the phase relationship, θ, that minimizes the EMI. The combined EMI is minimum when θ=360°/n and maximum when θ=0°. A system of two DCM Flyback SMPS is designed in such a way that both 0° and 180° phase shifts between input current waveforms are possible. In both cases EMI filters are designed to meet EMI standard MIL-STD-461. The system is simulated and constructed and the experimental results are presented. These results demonstrate the accuracy of the modeled waveform and the reduction of conducted EMI when optimal phasing is achieved.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/278520 |
| Date | January 1995 |
| Creators | Theodore, Susan Mack, 1958- |
| Contributors | Witulski, Arthur F. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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