【作者】 郭琦；

【导师】 徐殿国；

【作者基本信息】 哈尔滨工业大学 ， 电气工程（专业学位）， 2022， 硕士

【摘要】 随着环境问题的日益严重,中国提出“碳达峰”和“碳中和”的双碳目标致力于实现可持续发展保护生态环境。在实现“双碳”目标的过程中,新能源发电将起到关键的作用。直流微网接纳新能源发电上网,经一级高降压DC-DC变换器将电压调整到到预期值。因此,设计一种高效率高降压比的DC/DC转换器应用于直流微网具有重要意义。LLC谐振变换器是目前电源设计的首选结构之一,但LLC谐振变换器高频调节性能差,导致无功损耗大,并且参数设计自由度低,难以配置更优的工作参数。因此,本课题将在传统谐振电路的基础上予以改进,研究兼具高效率和高降压比的多元谐振电路。本课题首先分析开关电容堆叠桥CL-CLL谐振变换器的工作特性。对堆叠桥的输出电压作Fourier分解,阐明了预降压的原理。利用基波分析法对后级谐振腔做稳态研究,绘制基波等效电路图,便于后续分析。由于开关电容堆叠桥CL-CLL谐振变换器可以叠加三次谐波进行传输,所以从有功功率和变换器各处电流两个角度分析,阐明引入三次谐波对变换器性能提升的影响。对开关电容堆叠桥CL-CLL谐振变换器工作模态进行分析,对其工作过程予以展示。其次,本课题对开关电容堆叠桥CL-CLL谐振变换器进行参数设计方案的研究。从开关电容堆叠桥等效输出电阻和电压增益两个方面对前级开关电容容值进行设计。对后级多元谐振腔的参数设计中,提出一种新型的参数设计方案,要求配置的五元参数经频率匹配后满足增益条件和软开关条件。对变换器的参数离散性进行研究,从而辅助参数设计,配置最优的五元谐振参数。接下来,本课题对开关电容堆叠桥CL-CLL谐振变换器进行建模与控制。对开关电容堆叠桥CL-CLL谐振变换器进行准确的小信号建模,并且设计四极点-四零点补偿器从而改善变换器的闭环控制性能。根据开关电容堆叠桥CL-CLL谐振变换器可以引入电压零增益点这一特性,设计不断电的过流保护方案,可以在短路情况或者过流故障场合表现优良。最后,本课题搭建输入电压350V-450V,额定工作频率500k Hz,额定输出电压12V的开关电容堆叠桥CL-CLL谐振变换器实验样机,满载效率93.3%,符合预期设计指标。更多还原

【Abstract】 As environmental issues have received widespread attention,China has proposed the dual carbon goals of "carbon peak" and "carbon neutral" to achieve sustainable development and protect the ecological environment.In the process of realizing the "dual carbon" goal,new energy generation will play a key role.The DC microgrid accepts new energy power generation and the voltage is adjusted to the expected value through a high step-down DC-DC converter.Therefore,it is of great significance to design a DC/DC converter with high efficiency and high buck ratio applied to DC microgrid.LLC resonant converter is one of the preferred structures for power supply design at present,but LLC resonant converter has poor high-frequency regulation performance,resulting in large reactive power loss,and low freedom of parameter design,so it is difficult to configure better working parameters.Therefore,this topic will be improved on the basis of LLC resonant converter,design both high efficiency and high buck ratio of multi-order resonant converter.This topic first analyzes the working characteristics of CL-CLL resonant converter with stacked switch capacitor bridge.Fourier decomposition was performed on the output voltage of the stacked bridge to clarify the principle of the pre-step-down.The fundamental wave analysis method is used to study the steady state of the back resonant cavity,and the equivalent circuit diagram of the fundamental wave is drawn,which facilitates additional research.Since the CL-CLL resonant converter with stacked capacitance bridge can be transmitted by superposition of the third harmonics,the influence of introducing the third harmonics on the performance of the converter is analyzed from two perspectives of active power and current.The working mode of CL-CLL resonant converter with stacked switch capacitor bridge is analyzed and its working process is shown.Secondly,this topic to switch capacitor stacked bridge CL-CLL resonant converter parameters design scheme research.The capacitance of the front switch capacitor is designed from two aspects: equivalent output resistance and voltage gain.A new parameter design scheme is proposed for the parametric design of the post-stage multi-component resonator,which requires the five-element parameters to satisfy the gain condition and soft switching condition after frequency matching.The parameter discreteness of the converter is studied to assist the parameter design and configure the optimal five-element resonance parameters.Next,the modeling and control of CL-CLL resonant converter with stacked switch capacitor bridge is carried out.An accurate small signal modeling is carried out for CL-CLL resonant converter with switching capacitance stacked bridge,and a four-pole-four-zero compensator is designed to improve the closed-loop control performance of the converter.According to the characteristic that the CL-CLL resonant converter can introduce voltage zero gain point,the design of continuous overcurrent protection scheme can perform well in the case of short circuit or overcurrent fault.Finally,an experimental prototype of switching capacitor stacked bridge CL-CLL resonant converter with input voltage of 350V-450 V,rated operating frequency of 500 k Hz and rated output voltage of 12 V was built in this project.The full-load efficiency was 93.3%,which met the expected design indicators.更多还原