三相四线制高功率密度VIENNA整流器控制技术研究

发布时间：2018-03-24 15:58

本文选题：VIENNA整流器　切入点：三相四线制　出处：《华中科技大学》2015年硕士论文

【摘要】：随着人类对电能的需求越来越大、对电能的质量要求越来越高,电力电子装置广泛应用带来的电网的谐波问题、电磁干扰(EMI)问题和功率因数下降问题日趋严重。整流器作为电子设备连接电网的重要环节,其性能直接影响着这些装置对电网的污染程度。三相四线制VIENNA整流器因其独特的结构,可实现单位功率因数,并获得较高的转换效率和功率密度。因此,该拓扑广泛适用于中等功率的通信电源、航空设备及UPS等场合。为了进一步提高VIENNA整流器的功率密度,本文选择采用具有更好滤波效果的LCL型滤波器,并设计较小的输入电感使系统工作在电感电流混合导通模式(MCM)模式。根据三相四线制VIENNA整流器的物理解耦特性,获得解耦的单相三电平结构VIENNA整流器,在此基础上推导了VIENNA整流器的数学模型。通过其数学模型发现CCM和DCM模式下的电流环传递函数发生跳变,传统的控制策略已经无法在MCM模式下获得良好的系统性能。本文首先提出了CCM模式下基于前馈控制策略的控制方案,以消除输入电压、输出电压对电感电流的扰动。通过比较CCM和DCM模式下的小信号交流模型,在CCM模式下的前馈控制策略中加入校正系数后获得改进的控制方案。该控制方案可实现两种模式平滑地切换,并且不用复杂的开方运算和判断逻辑,减轻了数字控制器的负担。该校正系数也是MCM模式下电感电流平均值采样的校正系数,只需通过输入电压、输出电压和上一开关周期输出的占空比计算可得。改进型前馈控制策略很大程度上改善了VIENNA整流器MCM模式下的稳定性和系统性能,拓宽了整流器的工作负载范围。本文给出了VIENNA整流器CCM和DCM模式下的数学模型,以及LCL滤波器和改进型前馈控制方案的设计方法。最后,通过Simulink的S-Function模块进行C语言算法编程,模拟实际的数字控制器工作过程,对设计的系统参数和提出的改进型前馈控制策略的有效性和可行性进行验证。
[Abstract]:With the increasing demand for electric energy and the higher demand for the quality of electric energy, the harmonics of power grid caused by the wide application of power electronic devices are becoming more and more important. The problem of EMI) and the problem of decreasing power factor are becoming more and more serious. Rectifier is an important link in the connection of electronic equipment to the power network. Because of its unique structure, three-phase four-wire VIENNA rectifier can realize unit power factor and obtain higher conversion efficiency and power density. This topology is widely used in medium power communication power supply, aviation equipment and UPS. In order to further improve the power density of VIENNA rectifier, the LCL filter with better filtering effect is used in this paper. The small input inductance is designed to make the system work in the inductance current hybrid on-mode (MCM) mode. According to the physical decoupling characteristics of the three-phase four-wire VIENNA rectifier, the decoupling single-phase three-level VIENNA rectifier is obtained. On this basis, the mathematical model of VIENNA rectifier is derived. It is found that the transfer function of current loop in CCM and DCM mode jumps. The traditional control strategy can not achieve good system performance in MCM mode. Firstly, a feedforward control scheme based on feedforward control strategy in CCM mode is proposed to eliminate the input voltage. By comparing small signal AC models in CCM and DCM modes, An improved control scheme is obtained by adding correction coefficient into feedforward control strategy in CCM mode, which can smoothly switch two modes without complicated square operation and judgment logic. The positive coefficient is also the correction coefficient of the average sampling of inductance current in MCM mode, only through the input voltage. The output voltage and the duty cycle of the previous switching cycle are calculated. The improved feedforward control strategy greatly improves the stability and system performance of the VIENNA rectifier in MCM mode. In this paper, the mathematical models of VIENNA rectifier in CCM and DCM mode, and the design method of LCL filter and improved feedforward control scheme are given. Finally, the C language algorithm is programmed through the S-Function module of Simulink. The working process of the digital controller is simulated, and the validity and feasibility of the designed system parameters and the improved feedforward control strategy are verified.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM461

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