The Effect of Switching Frequency Modulation on the Differential-Mode Conducted Interference of the Boost Power-Factor Correction Converter

This paper investigates the use of switching frequency modulation in the reduction of the differential-mode conducted electromagnetic interference (EMI) of the offline boost power-factor correction converter. In particular, the EMI benefits obtained with modulation frequencies at and in excess of twice the line frequency are considered, incorporating the influence of average and quasi-peak (QP) detectors into the analysis and measurements. It is concluded that there is no significant change in the QP measurement unless the modulation frequency exceeds half the resolution bandwidth; however, up to 8-dB reduction in the average measurement, with no change in the QP measurement, can be obtained with modulation at twice the line frequency, for a switching frequency deviation of 20%. A digital modulation algorithm was devised and implemented using a digital-signal-processor-controlled converter. The reduction in the average detector measurement obtained for the digital modulation was comparable to that predicted for the linear modulation, but it delivers a more well-defined and predictable conducted EMI spectrum.

[1]  M. Albach.  Conducted interference voltage of AC-DC converters , 1986, 1986 17th Annual IEEE Power Electronics Specialists Conference.

[2]  M. J. Nave,et al.  A novel differential mode rejection network for conducted emissions diagnostics , 1989, National Symposium on Electromagnetic Compatibility.

[3]  F. Lin,et al.  Reduction of power supply EMI emission by switching frequency modulation , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[4]  Henry Shu-Hung Chung,et al.  Reduction of power converter EMI emission using soft-switching technique , 1998 .

[5]  Henry Shu-Hung Chung,et al.  Spectral characteristics of randomly switched PWM DC/DC converters operating in discontinuous conduction mode , 2000, IEEE Trans. Ind. Electron..

[6]  Hing Cheung So,et al.  Analysis and spectral characteristics of a spread-spectrum technique for conducted EMI suppression , 2000 .

[7]  M. J. Willers,et al.  An AC-DC converter with low input distortion and near unity power factor , 2002 .

[8]  Henry Shu-Hung Chung,et al.  A comparative study of carrier-frequency modulation techniques for conducted EMI suppression in PWM converters , 2002, IEEE Trans. Ind. Electron..

[9]  A. Santolaria,et al.  Evaluation of switching frequency modulation in EMI emissions reduction applied to power converters , 2003, IECON'03. 29th Annual Conference of the IEEE Industrial Electronics Society (IEEE Cat. No.03CH37468).

[10]  A. Orlandi,et al.  EMI reduction in switched power converters using frequency Modulation techniques , 2005, IEEE Transactions on Electromagnetic Compatibility.

[11]  R. Morrison,et al.  The realisation of the control of an AC/DC converter using a motor control DSP , 2005, 2005 European Conference on Power Electronics and Applications.