DC-DC变换器的级联稳定性分析与改善

发布时间：2019-06-06 07:56

【摘要】：分布式电源系统因具有很多的优点，越来越多的被应用为航天器的供电系统。在分布式电源系统中，存在很多子系统相互级联的部分，从而会影响整个系统的动态性能以及稳定性，基于以上问题，本课题将对DC-DC变换器级联系统的稳定性作出分析，同时对DC-DC变换器级联系统的稳定性做出改善。针对无阻尼滤波器和变换器级联稳定性的分析，本文主要通过建立小信号模型，分别从波特图、奈奎斯特判据和阻抗匹配的角度，给出级联不稳定的依据，对实际级联电路的稳定性做出分析，同时给出相应的实验验证，在此基础上利用实际实验，对无阻尼滤波器和变换器级联稳定的临界条件做出验证和分析，以便很好的说明此临界条件的正确性。针对无阻尼滤波器和变换器级联后不稳定的问题，本文利用设计阻尼滤波器的方法，来解决此问题，文中首先对不同结构阻尼滤波器的优缺点进行分析，从而可以根据不同的需要对阻尼滤波器进行选择，然后给出不同结构阻尼滤波器的设计原则和设计步骤，最后给出仿真和实验结果来验证设计思路的正确性，同时分析阻尼对于滤波器传递函数和输出阻抗的影响，给出相应结论。对于两个变换器相互级联的稳定性分析，利用前面建立的小信号模型，从不同的角度对两个变换器级联的稳定性做出分析，同时重点研究两个变换器级联后产生的低频振荡，利用等效的负载切换原理，把后级变换器等效成对前级变换器的负载切换，从而对两个变换器级联后低频振荡产生的原因和规律作出分析，同时研究负载对于低频振荡的影响，这部分不仅给出理论的分析，同时给出实验波形证明理论分析的正确性。对于两个变换器级联后产生的低频振荡或其他不稳定问题，本文主要是利用阻抗匹配的原则，保证后级变换器的性能不受前级变换器的影响，来设计中间级联滤波器，本文是在以前方法的基础上，做出相应的改进，使两个端口的阻抗差更大，从而更好地满足阻抗匹配，文中给出了单级中间滤波器具体的设计步骤，同时给出了仿真和实验结果，验证了设计思路的正确性，最后研究阻尼对于滤波器性能的影响，，给出相应的结论。本课题的研究为级联稳定性分析提供了理论依据，同时为改善级联不稳定现象的工程应用，提供了具有参考价值的解决方案。
[Abstract]:Distributed power supply system is more and more used as spacecraft power supply system because of its many advantages. In the distributed power supply system, there are many subsystems cascade parts, which will affect the dynamic performance and stability of the whole system. Based on the above problems, this paper will analyze the stability of the DC-DC converter cascade system. At the same time, the stability of the cascade system of DC-DC converter is improved. In view of the analysis of cascade stability of unobstructed filter and converter, this paper gives the basis of cascade instability from the point of view of baud diagram, Naiquist criterion and impedance matching, respectively, by establishing a small signal model. The stability of the actual cascade circuit is analyzed, and the corresponding experimental verification is given. on this basis, the critical conditions of the cascade stability of the unobstructed filter and the converter are verified and analyzed by using the actual experiment. In order to explain the correctness of this critical condition. In order to solve the problem of instability after cascade of undamped filter and converter, this paper uses the method of designing damping filter to solve this problem. Firstly, the advantages and disadvantages of damping filter with different structures are analyzed. Therefore, the damping filter can be selected according to different needs, and then the design principles and steps of damping filter with different structures are given. finally, the simulation and experimental results are given to verify the correctness of the design idea. At the same time, the influence of damping on the transfer function and output impedance of the filter is analyzed, and the corresponding conclusions are given. For the stability analysis of the cascade of the two converters, the stability of the cascade of the two converters is analyzed from different angles by using the small signal model established above. At the same time, the low frequency oscillations produced by the cascade of the two converters are studied. Based on the equivalent load switching principle, the back stage converter is equivalent to the load switching of the front stage converter, and the causes and laws of the low frequency oscillation after concatenation of the two converters are analyzed, and the influence of load on the low frequency oscillation is studied at the same time. This part not only gives the theoretical analysis, but also gives the experimental waveform to prove the correctness of the theoretical analysis. For the low frequency oscillation or other unstable problems caused by concatenation of two converters, this paper mainly uses the principle of impedance matching to ensure that the performance of the latter converter is not affected by the front converter to design the intermediate cascade filter. In this paper, on the basis of the previous method, the corresponding improvement is made to make the impedance difference between the two ports larger, so as to better meet the impedance matching. The specific design steps of the single-stage intermediate filter are given in this paper. At the same time, the simulation and experimental results are given to verify the correctness of the design idea. Finally, the influence of damping on the performance of the filter is studied, and the corresponding conclusions are given. The research of this paper provides a theoretical basis for cascade stability analysis and a reference solution for improving the engineering application of cascade instability.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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