| With the rapid development of information technology and power electronic technology,higher requirements are put forward for the performance of communication switching power supply.As an important part of communication system,DC-DC converter has great significance in improving its performance and reliability.Compared with the LLC resonant circuit and phase shifted full bridge circuit which are common in DC-DC structure,double transistor forward converter structure can overcome the bridge arm through problem inherent in the former two structures,so it has great research significance in the situation of high reliability requirements.In the development process of the two transistor forward converter,from the initial single transistor forward converter to the dual transistor forward converter,and then to the interleaved parallel dual transistor forward converter,the problems such as the effective duty cycle of the former two is less than 0.5,the voltage stress of the switch is high,and the output ripple is large are gradually solved.In view of the disadvantages of the traditional interleaving double switch forward topology,such as low utilization of magnetic core,hard opening of switch and complex circuit structure,this paper proposes a new interleaving double switch forward soft switch topology,which can suppress the parasitic vibration on the side of high frequency transformer.Firstly,this paper introduces the development and evolution of interleaving parallel double transistor forward DC-DC converter.Aiming at the topological structure and working principle of the circuit,it makes a comprehensive comparison and analysis of several typical interleaving parallel double transistor circuits in the existing research results at home and abroad,which is conducive to a deeper understanding of the background source and practical significance of this topic.This converter improves the traditional interleaving and parallel dual transistor topology,which makes the original independent two-way dual transistor branch share two reset diodes,not only simplifies the original magnetic reset circuit,but also further controls the number of circuit components.By integrating two independent cores of the primary winding into one,the converter topology design with higher power density is realized on the basis of ensuring the bridge arm’s reliable anti pass through.Secondly,the steady-state operation mode of the main circuit and the corresponding equivalent circuit of the converter are theoretically analyzed and derived.It is found that the phase-shift control mode can realize the zero voltage opening of all switches on the original side,and the ZVS realization condition of the lagging arm switch is mainly studied.Compared with the lead switch,it is difficult to realize the soft switch of the lagging arm switch under light load.According to the theoretical analysis,the main components of the converter are designed and selected reasonably.Using PSIM simulation software to simulate and analyze the main circuit,a series of voltage and current waveforms of the main circuit under different working modes are obtained,and the preliminary theoretical verification is realized.Finally,a test prototype of interleaving parallel double switch forward soft switching converter is built,with the rated power of 1k W and the switching frequency of100 k Hz.Through the key waveforms of the test prototype in the rated state,ZVS and transmitter The analysis of the experimental results of vibration generation verifies the rationality of the circuit design and effectively improves the stability and reliability of the communication switching power supply.This paper analyzes the principle of parasitic oscillation caused by the reverse recovery of diode on the secondary side of high frequency transformer,and designs a buffer circuit to quantitatively solve the problem of parasitic oscillation.Experiments show that RCD buffer circuit achieves better peak suppression effect than RC buffer circuit. |
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