ZVS对称半桥直流变换器及其设计
发布时间：2018-11-05 17:37
【摘要】：传统对称半桥电路结构和控制简单且具有自动抑制变压器磁偏的优点，在焊机中应用广泛。但是传统对称半桥电路工作于硬开关状态，且两个开关管同时关断时其变压器漏感与开关管寄生电容产生振荡，这些问题限制了焊机开关频率的提高，影响焊机的性能。针对传统对称半桥电路在焊机中的问题，本文提出了一种ZVS对称半桥直流变换器。 ZVS对称半桥直流变换器在传统对称半桥桥臂中点和分压电容中点加入了一支由两个反向串联的辅助开关管组成的辅助支路，，用于消除电路中的振荡，实现主辅开关的零电压开通；其主开关管的驱动信号与传统对称半桥变换器相同，辅助开关管的驱动信号由主开关管驱动信号经过一定延时得到,焊机中常用的脉宽调制芯片SG3525在此变换器中同样适用，其控制上容易实现。 论文详细分析了ZVS对称半桥直流变换器的工作原理，给出了变换器各个工作阶段的等效电路和等效方程；分析了ZVS对称半桥变换器的工作特性，结合变换器的工作过程推导了其软开关实现的条件，并设计了变换器的参数；建立了变换器的交流小信号模型并对其进行了闭环设计，利用焊机中常用的脉宽调制芯片进行了控制电路的设计，并给出了数字控制方案；分析了功率模块在ZVS对称半桥直流变换器中应用的问题，为功率模块的设计提供了参考。 最后，搭建了800W的实验样机，分别对传统对称半桥变换器和ZVS对称半桥变换器进行了实验分析，给出了两种变换器的效率曲线；实验结果验证了提出的变换器的可行性，且该变换器能够很好的应用于焊机电源中。
[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.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46
本文编号：2312811
[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.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46
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