Abstract—A rigorous mathematical analysis and a comparative study of carrier-frequency modulation (CFM) techniques for the conducted electromagnetic interference (EMI) suppression in pulsewidth-modulated converters is presented. CFM techniques dither the

TSEetal.:CARRIER-FREQUENCYMODULATIONTECHNIQUES

Fig.1.TypicalPWMfunction.

II.PCFMANDRCFM

Fig.1showsatypicalPWM

functionandtheswitching

periodhastwodiscretelevels

(namely,

canbe

expressedbyaFourierseries

[9]

thhar-monic,

respectively.

ismod-ulatedbyacosinusoidalfunctionof

amplitudeandfre-

quency

of

the

istheratioofthepeakinstantaneousfrequencydevia-tiontothefrequencyofthemodulatingsignal,namely,themod-ulationindexin[3]and[11].Itisdefined

as

619

is

the

(8)

NumericalvaluesoftheBesselfunctionswithrespect

to

uptothetenthorderaretabulatedinTableI.Thefollowingtwopropertiesarealso

noted:

(9a)

and