数字控制半桥LLC谐振变换器的研制

发布时间：2018-06-11 22:55

本文选题：LLC谐振变换器 + 数字控制　；参考：《广西大学》2017年硕士论文

【摘要】：随着分布式电源系统(DPS)在航空航天、电力系统、新能源汽车、计算机电源等各个高新领域的广泛应用,LLC谐振变换器成为了研究的热点。LLC谐振电路可以实现软开关特性,且输入电压范围相对宽泛,变压器副边不需要滤波电感,是目前较为适合应用在分布式电源系统中的一种电路拓扑。但是LLC谐振变换器工作原理复杂,谐振参数对频率变化敏感,其控制方式多以模拟控制为主,存在控制电路复杂,不灵活的缺点。因此,本文对基于数字控制的半桥LLC谐振变换器进行了深入研究。本文从频域分析的角度出发,依据稳态电路模型,讨论了谐振参数电感比k和品质因数Q对谐振变换器性能的影响,在上述讨论的基础上,依据工作条件,详细阐明了LLC谐振变换器谐振参数设计的步骤和方法,并在Saber仿真软件初步验证了谐振参数。根据参数设计的结果,对谐振电路各器件进行了设计或选型。本文讨论了LLC谐振变换器的小信号模型,选择增量式PI控制算法,在小信号模型的基础上,设计了PI控制的参数,分析了系统控制的稳定性和快速性,完成了控制环的设计;介绍了系统整体的硬件结构,选取数字信号处理器TMS320F28335作为控制单元,设计了其外围的采样电路和驱动电路,阐明了DSP中数字PWM的产生原理,编写了基于增量式PI的程序,给出了具体的程序流程。最后制作了输出功率240W,输出电压24V的实验样机并搭建了实验平台,测试出了不同条件下的电流电压波形图,并进行了分析,验证了理论分析和设计的正确性和可行性,取得了满意的效果。
[Abstract]:With the wide application of distributed power system (DPS) in aerospace, power system, new energy vehicle, computer power supply and so on, LLC resonant converter has become a research hotspot. LLC resonant circuit can realize soft switching characteristics. And the input voltage range is relatively wide, transformer secondary edge does not need filter inductor, is more suitable for the application of distributed power system circuit topology. But the principle of LLC resonant converter is complex, the resonant parameters are sensitive to frequency change, the control mode is mainly analog control, and the control circuit is complex and inflexible. Therefore, the half bridge LLC resonant converter based on digital control is studied in this paper. In this paper, the influence of resonant parameter inductance ratio k and quality factor Q on the performance of resonant converter is discussed according to the steady-state circuit model from the point of view of frequency domain analysis. The design steps and methods of resonant parameters of LLC resonant converter are described in detail, and the resonant parameters are preliminarily verified by Saber simulation software. According to the results of parameter design, the resonant circuit devices are designed or selected. In this paper, the small signal model of LLC resonant converter is discussed, and the incremental Pi control algorithm is selected. Based on the small signal model, the parameters of Pi control are designed, the stability and rapidity of the control system are analyzed, and the control loop is designed. This paper introduces the hardware structure of the whole system, selects TMS320F28335 as the control unit, designs its peripheral sampling circuit and driving circuit, expounds the principle of digital PWM generation in DSP, and compiles the program based on incremental Pi. The specific program flow is given. Finally, an experimental prototype of 240W output power and 24V output voltage is made and an experimental platform is built. The current and voltage waveforms under different conditions are tested and analyzed, and the correctness and feasibility of theoretical analysis and design are verified. Satisfactory results have been obtained.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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