發(fā)布時間：2018-11-05 17:37

【摘要】：傳統(tǒng)對稱半橋電路結(jié)構(gòu)和控制簡單且具有自動抑制變壓器磁偏的優(yōu)點，在焊機中應(yīng)用廣泛。但是傳統(tǒng)對稱半橋電路工作于硬開關(guān)狀態(tài)，且兩個開關(guān)管同時關(guān)斷時其變壓器漏感與開關(guān)管寄生電容產(chǎn)生振蕩，這些問題限制了焊機開關(guān)頻率的提高，影響焊機的性能。針對傳統(tǒng)對稱半橋電路在焊機中的問題，本文提出了一種ZVS對稱半橋直流變換器。 ZVS對稱半橋直流變換器在傳統(tǒng)對稱半橋橋臂中點和分壓電容中點加入了一支由兩個反向串聯(lián)的輔助開關(guān)管組成的輔助支路，，用于消除電路中的振蕩，實現(xiàn)主輔開關(guān)的零電壓開通；其主開關(guān)管的驅(qū)動信號與傳統(tǒng)對稱半橋變換器相同，輔助開關(guān)管的驅(qū)動信號由主開關(guān)管驅(qū)動信號經(jīng)過一定延時得到,焊機中常用的脈寬調(diào)制芯片SG3525在此變換器中同樣適用，其控制上容易實現(xiàn)。 論文詳細(xì)分析了ZVS對稱半橋直流變換器的工作原理，給出了變換器各個工作階段的等效電路和等效方程；分析了ZVS對稱半橋變換器的工作特性，結(jié)合變換器的工作過程推導(dǎo)了其軟開關(guān)實現(xiàn)的條件，并設(shè)計了變換器的參數(shù)；建立了變換器的交流小信號模型并對其進行了閉環(huán)設(shè)計，利用焊機中常用的脈寬調(diào)制芯片進行了控制電路的設(shè)計，并給出了數(shù)字控制方案；分析了功率模塊在ZVS對稱半橋直流變換器中應(yīng)用的問題，為功率模塊的設(shè)計提供了參考。 最后，搭建了800W的實驗樣機，分別對傳統(tǒng)對稱半橋變換器和ZVS對稱半橋變換器進行了實驗分析，給出了兩種變換器的效率曲線；實驗結(jié)果驗證了提出的變換器的可行性，且該變換器能夠很好的應(yīng)用于焊機電源中。
[Abstract]:The traditional symmetrical half-bridge circuit has the advantages of simple structure and control and automatic suppression of transformer magnetic deviation, so it is widely used in welding machine. However, the traditional symmetrical half-bridge circuit works in hard-switching state, and the leakage inductance of transformer and parasitic capacitance of switch tube oscillate when two switches are turned off at the same time. These problems limit the increase of switching frequency of welding machine and affect the performance of welding machine. Aiming at the problem of traditional symmetrical half-bridge circuit in welding machine, a ZVS symmetrical half-bridge DC / DC converter is proposed in this paper. The ZVS symmetrical half-bridge DC / DC converter adds an auxiliary branch composed of two auxiliary switches in series to eliminate the oscillation in the circuit. The zero voltage of the main and auxiliary switch is turned on; The driving signal of the main switch tube is the same as that of the traditional symmetrical half-bridge converter. The driving signal of the auxiliary switch tube is obtained by the driving signal of the main switch tube after a certain delay. The pulse width modulation chip SG3525, which is commonly used in the welding machine, is also applicable in this converter. Its control is easy to realize. In this paper, the working principle of ZVS symmetrical half-bridge DC / DC converter is analyzed in detail, and the equivalent circuit and equivalent equation of each stage of the converter are given. The operating characteristics of ZVS symmetrical half-bridge converter are analyzed, the conditions of its soft-switching realization are deduced according to the working process of the converter, and the parameters of the converter are designed. The AC small signal model of the converter is established and the closed-loop design is carried out. The control circuit is designed by using the pulse width modulation chip commonly used in the welding machine, and the digital control scheme is given. The application of power module in ZVS symmetrical half-bridge DC / DC converter is analyzed, which provides a reference for the design of power module. Finally, the 800W experimental prototype is built, the traditional symmetrical half-bridge converter and ZVS symmetrical half-bridge converter are analyzed, and the efficiency curves of the two kinds of converters are given. The experimental results verify the feasibility of the proposed converter, and the converter can be well used in the welding power supply.
【學(xué)位授予單位】：燕山大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM46

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本文編號：2312811