Research And Development Of 12KW 28VDC/125VDC Converter

High-power and low-input voltage DC/DC converter is required in one "863 program" project. Based on comparison of different DC/DC converters, Push-Pull Forward converter (PPF) is selected as main circuit prototype. For high power system, Parallel technology of many DC/DC modules is adapted. In this paper, the operating principle of the PPF is introduced. The problems of freewheeling current are detailed. Analysis and simulation is performed, with the results that, the proper selection of clamping capacitor, transformer leakage inductance are critical to the proper working of the converter. Then, this paper designs prototype of 2KW 28VDC/125VDC module and analyzes power loss. The mathematical model of PPF is set up to optimize control parameters. In order to improve the accuracy of current sharing system, this paper presents a new current sharing method—direct current sharing in current loop. This method is adapted to apply in 12KW 28VDC/ 125VDC converter system consisted of six 2KW 28VDC/ 125VDC modules. The experimental results confirm that this current sharing method has many advantages, such as high accuracy, flexibly dynamic performance, simple communication among every module and high reliability.