Current-Fed High-Conversion-Ratio Bidirectional DC-to-DC Converter with Coupled-Inductors and Switched-Capacitors

• Main Authors: Chung-YuChen, 陳重佑
• Other Authors: Hong-Tzer Yang
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/43125470604540944246

碩士 === 國立成功大學 === 電機工程學系 === 103 === Due to environmental consideration and increase of load demand, renewable energy is widely used nowadays. However, its unreliable and intermittent characteristics cause problems of power supply reliability. To solve the problem, an energy storage system (ESS) may be used not only to improve the stability of distribution power system with renewable energy integrated, but also relieve the intermittence of renewable energy. Therefore, used to coordinate power flow between ESS and distribution power system, a bidirectional DC-to-DC converter becomes an important research topic. A new current-fed high-conversion-ratio bidirectional DC-to-DC converter integrated coupled-inductors and switched-capacitors are proposed for the application in ESS. With the current-fed configuration, continuous low-ripple input current can be achieved, which can avoid the use of input electrolytic capacitor to enhance the reliability of the whole system. High-conversion-ratio is obtained by coupled-inductors and switched-capacitors. In boost mode, switches at high voltage side can achieve soft-switching. The efficiency can thus be enhanced due to the reduction of conduction loss. In buck mode, each of the switches can have soft-switching. Leakage energy on secondary side can be recycled by active-clamped circuit. Thus, the efficiency can be further improved as well. Operation principles, voltage stress analyses, and design guidelines of components used in the proposed circuit are discussed in detail in the thesis. Finally, a 24V low-side voltage, 400V high-side voltage, and 200W rated prototype power circuit has been implemented in the thesis to verify its effectiveness. According to the experimental results, a maximal efficiency 95.5% and 92.3% at rated power are obtained while in boost mode. In buck mode, a maximal efficiency 93.2% and 87.7% at rated power are observed.