A Novel ZVZCS Full-Bridge DC/DC Converter Used ... - IEEE Xplore

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PAHLEVANINEZHAD et al.: NOVEL ZVZCS FULL-BRIDGE DC/DC CONVERTER USED FOR ELECTRIC VEHICLES 2755Fig. 3.Ideal waveforms of the converter.During this interval, the secondary-side diodes are reversed biasedand are OFF. Therefore, the rising voltage v AB conductsa very small current through the DC blocking capacitor C b ,seriesinductance L s , leakage inductance L leak , and magnetizinginductance L M . Fig. 4(a) shows the active components in thismode of operation. The current through the series inductanceL s , is given by∫1ti s (t) =v AB dt. (1)L s + L leak + L M t 0Due to the fact that L M is large, the amount of current flowingthrough the primary side of the transformer is much smaller than
2756 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 27, NO. 6, JUNE 2012Fig. 4 (a) Active components of Mode I. (b) Active components of Mode II. (c) Active components of Mode III. (d). Active components of Mode IV. (e) Activecomponents of Mode V. (f) Active components of Mode VI. (g) Active components of Mode VII.the current through the auxiliary circuit i AUXA . According tothis assumption v AB is calculated asv AB (t) =V dc − v Cso (t) (2)v Cso (t) =V dc − I PA(t − t 0 ). (3)2C soBy using (1)–(3), the equation of the series current is calculatedasi s (t) =I PA4(L s + L M + L leak ).C so(t − t 0 ) 2 . (4)This interval ends once the voltage across the secondaryreaches the output voltage plus the voltage drops of the diodesto forward bias the output diodes. Thus, t 1 is given byt 1 = t 0 + 2k(V o +2V d ).(L s + L M + L leak ).C soL M .I PA. (5)Mode II (t 1 ≤ t ≤ t 2 ): This mode starts once the outputdiodes get forward biased. Fig. 4(b) shows the active componentsin this mode. According to this figure, the output capacitorof the MOSFET, S 1 is still discharging to finally reach zero andthat of S 2 is charging up to V dc . This mode ends once the voltageacross this capacitor becomes zero. In this interval, the series
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A Novel ZVZCS Full-Bridge DC/DC Converter Used ... - IEEE Xplore

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