Research on high efficiency power conversion circuits with low conduction loss zero voltage switching technique

Abstract

To realize the high efficiency DC/DC converter in distributed power architecture, both soft switching technique and low conduction loss are suggested. However, in general, the soft switching technique, such as zero voltage switching, causes large conduction loss, or, conversely, the low conduction loss induce the non-capability of soft switching. Thus, this dissertation suggests that the conduction loss is reduced effectively with the soft switching capability. First, new PWM-controlled quasi-resonant converter for a high efficiency PDP sustaining power module is proposed. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the primary resonant capacitor with a bi-directional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good ZVS capability, simple control circuits, no high voltage ringing problem of rectifier diodes, no DC offset of the magnetizing current and low voltage stresses of power switches. Thus, the proposed converter shows higher efficiency than that of a half bridge LLC resonant converter under light load condition. Although it shows the lower efficiency at heavy load, because of the increased power loss in auxiliary circuit, it still shows the high efficiency around 94%. Secondly, new phase shifted full bridge (PSFB) converter with voltage doubler type rectifier for high efficiency PDP sustaining power module is proposed. This converter employs a voltage doubler rectifier without an output inductor. Since it has no output inductor, the voltage stresses of the rectifier diodes can be clamped at the output voltage level. Thus, because no dissipative resistor-capacitor snubber for rectifier diodes is needed, high efficiency, as well as, a low noise output voltage can be r...