Study On Maximum Current Mode Automatic Current Method And Lossless Passive Soft Switch Technology Of Two Transistor Forward Converter

With the development of recent years, switch power technology has been gradually matured. A high power and high performance of switch power supply has become a goal, which people have being innovating and chasing. The current sharing technology of the parallel system and the soft switch technology has become the key point and hot spot of the development of the electric power industry, which were combined could largely meet in volume, high efficiency, reliability requirements of the high power supply.This paper presents a new type of lossless passive soft switch technology, in order to solve the problem of the power switch hard opened and hard closed, realizing zero current closed and zero voltage opened of the power switch tube. With the process of the module parallel, presenting a novel maximum current mode automatic current method, in order to solve the unevenly distributed problem of the parallel modules of the power distribution, because every power module has various electric characteristic. The main content of this article as follows:Firstly, introducing the two transistor forward converter, analysising the basic circuit structure and working principle, then list the main equation of the main circuit, using the control chip of SG3525to design control circuit and the protecting circuit. Secondly, researching the topology for two transistor forward converter, designing the LCD clamping circuit of the primary side switched tube and the RCD clamping circuit of second side freewheeling diode(FWD) respectively, meanwhile analysing the working process of the two clamped circuits. Thirdly, elaborating the current sharing general principles of the parallel modules, getting through the comparison of the common current sharing technology of the parallel system, presenting base on the characteristics of the maximum current mode automatic current method, setting up small signal modeling of the control circuit, displaying voltage loop, current loop, current sharing loop, using MATLAB tools, drawing the Bode of the loop, discussing the stability of the parallel system.Through setting up two sample converters, carrying on the parallel experiment and data measurement. we can prove that the designed of the lossless passive condition soft switch technology is feasible, and can improve the efficiency. At the same time it also demonstrate the good performance of the control circuit, proving the validity of the theoretical analysis.