【作者】 黄煜；

【导师】 邾玢鑫；

【作者基本信息】 三峡大学 ， 电气工程（专业学位）， 2021， 硕士

【摘要】 由于传统化石能源的日益短缺以及全球环境问题的日益突出,太阳能、燃料电池等新型可再生能源并网发电及燃料电池汽车逐渐成为近年来的研究热点。然而受到自然环境的影响,光伏电池板输出的低电压在较宽的范围内变化;另外,燃料电池的输出特性较“软”,随着电池输出端电流的增加,其输出电压会降低,导致燃料电池输出电压存在较宽的变化范围。然而,针对新能源并网和燃料电池汽车这些应用场合,逆变器直流母线侧对输入电压稳定的要求较高。因此,为了使逆变器直流母线电压在新能源电池低压侧发生变化时仍然能够维持所需的稳定电压值,需要开发一种能够适应宽范围输入电压的高升压比DC/DC变换器。本文首先通过对目前应用于新能源电池的各类常见DC/DC变换器进行归纳总结,提出一种新型非隔离DC/DC变换器:基于可拓展电压增益单元的Sepic变换器,该变换器在实现高增益、宽范围输入电压的同时,还具备器件电压应力低、输入电流连续纹波小、驱动和控制方式简单的特点。此外,所提变换器可以根据电压增益需求,对增益单元数量进行拓展,进一步提高变换器的增益比。因此,所提变换器能够较好地应用于新能源并网发电、燃料电池汽车等场合。其次,分析了所提变换器的工作原理与性能特点,推导出输入输出电压增益和所有元器件应力的理论计算公式,并给出了主电路器件参数的设计过程,采用平均开关模型法对变换器进行建模,完成了控制系统环路补偿设计。为了验证电路拓扑的可行性和控制策略的正确性,建立Psim仿真模型对变换器进行仿真验证,并搭建了一台功率为300W实验样机对变换器进行实验验证。接着给出了整个闭环控制系统软硬件的设计过程,控制系统以TMS320F28335为控制核心,采用电压电流双环控制策略,给出了硬件电路图和程序设计流程。仿真、实验结果与理论分析相一致,验证了所提变换器的正确性和所设计控制方案的合理性。最后,为了减小变换器体积、实现更高的高功率密度。本文通过对前文所提变换器的拓扑结构进行优化设计,得到电容电压应力更低的改进型变换器拓扑结构,并在此新拓扑基础上选用能够实现更高频率的新型氮化镓开关器件,通过提升开关频率使无源器件体积减小,进而提高开关电源的功率密度。基于理论分析,给出了改进后变换器的主电路参数和高频驱动电路的设计过程,并搭建了一台小功率实验样机,验证此方案的正确性和可行性。更多还原

【Abstract】 In recent years,due to the increasing shortage of traditional fossil energy and the increasingly serious global environmental problems,the renewable and clean energy such as solar energy and full cell have draw a great attention in grid-connected generation and fuel cell vehicles.However,under the influence of climatic conditions,solar panels supply low and wide range of output voltage.In addition,the fuel cell has a “soft” output voltage characteristic.As the output current increases,the output voltage will drop,which results in wide output voltage range.In order to make the DC bus voltage of inverter maintain the requied and stable voltage when the low output voltage of solar panels and fuel cell changes,thus the boost DC/DC with a wide input voltage rang and high voltage gain is needed to act as required power interface between the new energy battery and dc bus for new energy generation and fuel cell vehicles.Firstly,various kinds of common DC/DC converters,which are currently used in fields of new energy generation and fuel cell vehicles,are briefly summarized.And an extendable voltage multiplier(VM)cells applied to SEPIC converter was proposed in this paper,the converter has some advantages such as high voltage gain,wide input voltage range,low voltage stress on switch and diodes,continuous and low ripple input current.At the same time,the proposed voltage multiplier cell does not contain active switches,so that the driver and control circuits of the SEPIC converter are adapted to proposed converter,no changes are needed.Beside,the topology can be extended according to the voltage gain requirement,thus the proposed converter can achieve higher voltage gain by adjusting the number of VM cells.Therefore,the proposed converter is suitable for the applications such as new energy generation and fuel cell vehicles.Secondly,the operating principles and performance characteristics of the proposed converter are analyzed,the theoretical calculation equations for the voltage gain and the stresses of all components are deduced.Then,the design processes of the devices parameters are given.The averaged switch method is adopted to model the converter in order to complete the design of control system loop compensation.A Psim simulation model is established to verify the feasibility of the proposed converter and the correctness of control strategy,and an experimental prototype with rated power of 300 W is built to verify proposed converter.The design process of hardware and software of the closed-loop control system is given.The main controller adopts TMS320F28335 and the control strategy is voltage-current dual loop control method.The hardware circuits and program design flow are given.The simulation and experimental results are consistent with the theoretical analysis,which verify the correctness of the proposed converter and effectiveness of control strategy.Finally,in order to reduce converter volume and improve system power density,a improved converter with lower voltage stress on capacitors is obtained by optimizing the topology of the aforementioned converter.Then the modified converter operates in a 1MHz frequency by utilizing Ga N device.As the switching frequency increases,the size of passive components reduces and the power density of switch-mode power supply improves.Based on the theoretical analysis,the main circuit and high frequency driver circuit of the improved converter are designed,and experimental prototype is built to verify the effectiveness of the proposed scheme.更多还原