Study Of Half Bridges In Series Hybrid DC-DC Converters

With the development of Power Electronics, Switching Mode Power Supply (SMPS) has been more and more applied in various fields. However, the vast applications of SMPS carry two negligible penalties on supply network: harmonics disturbance and reactive current. In order to overcome the two penalties and implement the "green power supply", the technology of Active Power Factor Correction (APFC) start to be using in SMPS. But, the output voltage of APFC is rather high, therefore the DC-DC converter's switches need high rated voltage. For the sake of reducing voltage stress of switches, the topologies DC-DC converter, which can not only achieve soft switching but also reduce voltage stress of switches, become a research focus in recent years. Thereinto, the main two topologies are three-level DC-DC converter and half bridge in series hybrid DC-DC converter. The latter is studied and developed in this paper.This paper analyzes the causation of unbalanced-voltage-division inheres in two half bridges' input capacitors in the symmetrical half bridges in series hybrid DC-DC converter. Based this analysis two methods be proposed to overcome above drawback. The two methods is balanced charging and eliminating loop current. Two DC-DC converters are proposed based on the two methods, which are Half Bridges in Series Hybrid DC-DC Converter with Current Doubler Rectifier and Asymmetrical Half Bridge in Series Hybrid DC-DC Converter. The principle and characteristics of the two novel converters are analyzed respectively. The two converters are simulated in Saber, which is power electronics simulation software. Two prototypes are built to validate the two converters' characteristics. The experimental results are presented in the end.