Zero Voltage Switching Full-Bridge Converter with Two Different Control Schemes

Autor: Jun-Han Chen, 陳俊翰
Rok vydání: 2015
Druh dokumentu: 學位論文 ; thesis
Popis: 103
A conventional full-bridge converter has been widely used in high input-voltage, high-power applications. Several control schemes have been applied to full-bridge converter, such as symmetrical control, phase shift control, duty cycle control, and asymmetrical control. Among these, duty cycle control and asymmetrical control have been seldom discussed and will be investigated in this thesis. Employing symmetrical control, full bridge has been used for a long time. It suffers from large switching losses due to its hard-switching operation. It will impact the conversion efficiency and limit power density. To improve the efficiency, phase shift full-bridge converter (PSFB) was successfully proposed instead in the last three decades. Because it can achieve ZVS operation, the switching turn-on losses are significantly reduced. To further improve efficiency, the conduction losses of the rectifier diode can be decreased by employing synchronized rectifier technique. However, two additional driver signals are not available in the popularly used phase shift controllers, such as UC3875 and UC3895. As an alternative control scheme, full-bridge converter with duty cycle control (FBDC) is investigated. In addition to inheriting the advantages and the disadvantages of PSFB, FBDC can directly provide synchronous rectification driver signals if higher efficiency and simple controller design are demanded. However, a circulation loss problem occurs in FBDC as well as in PSFB. Accordingly, a full-bridge converter with asymmetrical control is thus examined. In addition to the descriptions of the operation principle and design consideration, two hardware circuits, FBDC and AFB, with same 300-400-V input and 12-V/ 360W output specifications were built and compared.
Databáze: Networked Digital Library of Theses & Dissertations
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