Analysis and design of a dual series-resonant DC-DC converter

Tahavorgar, Amir (2017) Analysis and design of a dual series-resonant DC-DC converter. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (4MB)

Abstract

DC-DC conversion systems are vital components in DC distribution systems, renewable energy generation systems, telecommunication systems, and portable electronics devices. The extensive applications of DC-DC converter have resulted in continuous improvement in the topologies and control methods in these converters. The challenge is to build a converter that improves factors such as efficiency of conversion and power density with a simple topology, which incorporates simplified switching and control schemes and fewer numbers of active and passive components to reduce the manufacturing cost. This thesis addresses this challenge by proposing an alternative topology of a DC-DC converter based on dual series-resonant circuits. The proposed topology operates under zero voltage switching (ZVS) and zero current switching (ZCS) conditions to reduce the switching losses. It achieves two degrees of freedom (i.e., duty ratio and switching frequency) to control the output voltage of the converter, which results in both step-down and step-up voltage conversions. The number of active components is limited to two semiconductor switches and two rectifying diodes, which reduces the manufacturing cost of the converter. Detailed analytical analysis is carried out using the extended describing function methodology to characterize the steady state and small signal operation of the converter. Small-signal transfer functions are developed and used to propose a simple closed-loop control scheme to control the output voltage of the converter. An experimental 10 V, 40 W prototype of the proposed converter is built and tested to investigate its operation and confirm its features. The improvement in the efficiency of the converter and power transfer capability of the proposed dual series-resonant converter compared with the traditional single series-resonant circuit, which is used in the interleaved topologies are experimentally verified. In addition, soft switching operation of the converter is realized and a simple control scheme is developed to control the output voltage of the converter. A detailed and step-by-step design procedure is developed, which can be used to customize the design of the converter for different levels of power and voltage. It is shown that the proposed dual series-resonant DC-DC converter provides significant improvement regarding power density, efficiency of power conversion, simplicity of switching and control schemes, and reduced number of converter components resulting in a low cost and compact converter.

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