High-Power Bidirectional DC/DC Converter with Natural Commutation

• Main Authors: Chi-Rong Chen, 陳麒容
• Other Authors: Huang-Jen Chiu
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/84354102352686414747

碩士 === 國立臺灣科技大學 === 電子工程系 === 103 === This thesis proposes a high-power bidirectional DC/DC converter for micro-grid system applications. The power-stage circuit topology is a non-isolated buck-boost DC/DC converter. Conventionally, this topology is hard-switched, which results in significant switching losses, as well as induces electromagnetic interferences and high-frequency noises. Contrarily, a novel control strategy is proposed in this thesis, in which zero-voltage-switching (ZVS) of power switches can be realized with simple pulse-width-modulation. The term “natural commutation” here means that inductor current keeps flowing reversely through the switched-on path. This reversed current will accordingly release the energy stored in the parasitic capacitance of the power switches, which significantly reduces the switching loss. Specifically, even at light-load condition, the conversion efficiency can be improved easily by this control strategy and achieves high efficiency under wide-range load variations. The circuit topology and the operation principles are analyzed in detail in this thesis. According to the design rules, a 2 kW bi-directional converter is built to test its feasibility. The power efficiency is higher than 96 % .