| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 107 === This thesis mainly discusses the problems faced by full-bridge converters in the application of wide output voltage range. The action principle analysis of the traditional hard-switching full-bridge and full-bridge phase-shift converters will be introduced. And to explore the effect of the parasitic components on the circuit when the above two architectures are applied in a full-bridge boost/buck converter.
This thesis proposes a full-bridge converter that used the AC switch for secondary side rectification. Using two windings of secondary-side rectifying and connect their outputs in series to increase the output voltage. Through the duty cycle adjustment of the AC switch, the energy storage time of the two sets of output inductors is staggered to reduce the current peak of the primary side. When the primary side of the full bridge is in the dead time, the freewheeling is limited by the AC switch. Therefore, the voltage across the transformer will not be clamped at zero volts, so the energy on the magnetizing inductance can release the parasitic capacitance energy of the primary side power switch to zero, achieving zero voltage switching.
In the architecture part, this paper uses two sets of center-tapped rectifying windings and outputs them in series, and the rectifying diodes are replaced by AC switches. And adding a freewheeling diode to provide a freewheeling path for the output inductor. Finally, the circuit achieves an input voltage of 380 V, an output voltage range of 150 V to 500 V, an output power of 600 W, a full-bridge converter with a switching frequency of 80 kHz, and an efficiency is up to 95% at full load.
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