The phase shift full bridge (PSFB) converter allows high efficiency power conversion at high frequencies throughudzero voltage switching (ZVS); the parasitic drain-to-source capacitance of the MOSFET is discharged by a resonantudinductance before the switch is gated resulting in near zero turn-on switching losses. Typically, an extra inductance is added to the leakage inductance of a transformer to form the resonant inductance necessary to charge and discharge the parasitic capacitances of the PSFB converter. However, many PSFB models do not consider the effects of theudmagnetizing inductance or dead-time in selecting the resonant inductance required to achieve ZVS. The choice ofudresonant inductance is crucial to the ZVS operation of the PSFB converter. Incorrectly sized resonant inductance willudnot achieve ZVS or will limit the load regulation ability of the converter. This paper presents a unique and accurateudequation for calculating the resonant inductance required to achieve ZVS over a wide load range incorporating theudeffects of the magnetizing inductance and dead-time. The derived equations are validated against PSPICE simulationsudof a PSFB converter and extensive hardware experimentations.
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