u4)FromAmplitudemodulationofsinusoidalwaveto Sinusoidal PulsewrtWidth Modulation(SPWM)udaled:Eguivalentsinusoidalwavecttytb)
4）From Amplitude modulation of sinusoidal wave to SinusoidalPulse Width Modulation (SPWM) Equivalent sinusoidal wave
1.2 Terms of SPWM1) CarrierfrequencyAtriangular ( Vri asshown on this page) orsaw-teeth wave at aswitching frequency fs（六）which establishes the(a)frequency with which aUinverter are switched.This frequency is usuallycalled carrier frequencytor switching frequency fs(b)
1.2 Terms of SPWM 1) Carrier frequency A triangular ( vtri as shown on this page) or saw-teeth wave at a switching frequency fs, which establishes the frequency with which a inverter are switched. This frequency is usually called carrier frequency fc or switching frequency fs
Ucontrol2) Modulating frequencyA control signal Vcontrol isused to modulate theswitch duty ratio and hasH)a frequency f1, which is(a)the desired fundamentalfrequency of outputvoltage. This frequency isusually called modulatingfrequency or fundamentalfrequency fi.(b)
2) Modulating frequency A control signal vcontrol is used to modulate the switch duty ratio and has a frequency f1, which is the desired fundamental frequency of output voltage. This frequency is usually called modulating frequency or fundamental frequency f1
Ucontrol3) Amplitude modulationratio (index) macontrolm）tri(a)Uo4)Frequency modulationratio (index) mffsmJi(b)
tri control ma Vˆ = Vˆ 4) Frequency modulation ratio (index) mf 1 f mf = fs 3) Amplitude modulation ratio (index) ma
Vcontrol5) The peak amplitude of thefundamental-frequencycomponent is m, times (Va/2)LV=m(m。≤1)Aoa2X(a)6) Sidebandsharmonics: thoseharmonics appeararound the carrierfrequency and itsmultiples(b)
5) The peak amplitude of the fundamental-frequency component is ma times (Vd /2) 2 a d (m 1) （ V Vˆ ) = m Ao 1 a 6) Sidebands harmonics: those harmonics appear around the carrier frequency and its multiples