| Summary: | 博士 === 國立臺灣科技大學 === 電子工程系 === 98 === This dissertation proposes a push-pull boost power factor corrector (PFC). It is composed of two boost converters with a coupled inductor. The two identical modules can share the output power and increase the power capability up to the medium power level applications. The main advantage is coupling the two independent boost inductors into a single magnetic core to substantially reduce the circuit volume and the cost without degrading the conversion efficiency too much, which are the important targets of the modern switching power supply design. The interleaved operations of the switches with a cut-in-half duty cycle can reduce the conduction losses of the switches as well as both the turns and diameters of the inductor windings, which help more to the reduction of the circuit volume. Moreover, the operating frequency of the core, and thus the frequency of the two-phase inductor current ripple, is double that of the switching frequency. Also the ripple current at the input side and the output capacitor size are reduced. The power factor and the power density are improved.
The operations of the proposed PFC can be under either quasi-resonant (QR)
mode or discontinuous conduction mode (DCM). For QR mode operation, the
valley-switching on the switch and zero-current-switching (ZCS) of the output diode can reduce the switching losses and improve the conversion efficiency. On the other hand, the DCM operation feature fixed switching frequency, ZCS of the output diode, natural PFC function, simplified control methodology and EMI filter design. Circuit theorems and design procedures are presented and verified by the simulations and experimental results. In addition, the dual-mode operation combining QR mode and DCM is proposed and preliminarily verified to improve the light load efficiency while maintaining the high heavy-load efficiency. Finally, the concepts of the proposed PFC are further extended to other topologies.
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