谐振电容电压控制LLC谐振变换器研究

发布时间：2018-11-20 09:53

【摘要】：分布式电源系统具有可靠性高、抗干扰性强等诸多的优点在计算机系统中被广泛的应用。其前端变换器往往需要满足高频化、高效率化以及高密度化等要求,这使得传统的硬开关PWM变换器在应用上受到限制。LLC谐振变换器是当前比较具有代表性的软开关拓扑之一,其在宽负载范围下能够实现主开关管的软开关,而且易于磁集成,因此在分布式电源系统中被广泛采用。目前电压型控制策略仍然是LLC谐振变换器最常用的控制策略,但随着变换器的广泛应用,在动态响应速度、过流保护、短路保护等方面该控制策略显现出很大的缺陷,鉴于这个问题,论文研究了一种基于次级反馈的电荷控制。首先,对该控制方法的工作原理进行了详细的分析,并对其在输入扰动与负载扰动下的调节规律展开了讨论；其次,通过稳态分析推导了控制环路中主要参数的表达式,并设计参数搭建了仿真电路。此外,论文提出了一种谐振电容电压控制,与电压型控制相比,谐振电容电压控制通过简单的电容分压网络实现对电流信息的采样,不需要电流互感器,减少了变换器的体积,简化了控制环路,提高了变换器的动态响应速度。论文对该控制方法的工作原理、调节规律以及参数设计原则进行了详细的分析,并搭建了仿真电路。最后,搭建了谐振电容电压控制LLC谐振变换器的实验平台,给出了该实验平台主电路的参数设计、关键器件的选型以及控制电路主要结构单元的PCB原理图。实验结果表明,相比电压型控制,其动态响应效果更好。
[Abstract]:Distributed power system has many advantages such as high reliability, strong anti-interference and so on. It is widely used in computer system. The front-end converter often needs to meet the requirements of high frequency, high efficiency and high density, which makes the traditional hard-switching PWM converter limited in application. LLC resonant converter is one of the representative soft switching topologies. It can realize the soft switch of the main switch in the wide load range, and is easy to integrate with magnetic field, so it is widely used in the distributed power system. Voltage mode control strategy is still the most commonly used control strategy for LLC resonant converters. However, with the wide application of the converter, the control strategy shows great defects in dynamic response speed, over-current protection, short-circuit protection and so on. In view of this problem, a charge control based on secondary feedback is studied. Firstly, the working principle of the control method is analyzed in detail, and the regulation law of the control method under the input disturbance and load disturbance is discussed. Secondly, the expression of the main parameters in the control loop is deduced by steady-state analysis, and the simulation circuit is built. In addition, a kind of resonant capacitor voltage control is proposed. Compared with the voltage mode control, the resonant capacitor voltage control can sample the current information through a simple capacitive divider network, which does not require a current transformer, thus reducing the volume of the converter. The control loop is simplified and the dynamic response speed of the converter is improved. In this paper, the working principle, regulation law and parameter design principle of the control method are analyzed in detail, and the simulation circuit is built. Finally, the experimental platform of resonant capacitor voltage controlled LLC resonant converter is built. The design of main circuit parameters, the selection of key devices and the PCB schematic diagram of the main structure of the control circuit are given. The experimental results show that the dynamic response is better than voltage mode control.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM46

【相似文献】