【作者】 俞鹏；

【导师】 王明渝；

【作者基本信息】 重庆大学 ， 电气工程， 2011， 硕士

【摘要】 现实生活中常遇到一些特殊状况使得设备的输入电压会超出常规范围变化。宽范围输入电压可能会导致控制系统的不稳定,同时容易使电子器件所承受的应力超出其耐压耐流水平,造成设备过热甚至烧毁。军用特种车因其特殊的应用环境,输入电压常出现宽范围变化情况。然而,其内部电子设备对输入电压的稳定性要求很高,28V稳定的直流电压是这些电子设备常需的电压,且要求供电电源模块动态特性好、体积小、稳定性高。本文针对于军用特种车载系统中遇到的宽范围输入电压问题,提出了一种由双管BuckBoost电路与双管正激变换电路级联的两级式DC/DC变换器的解决方案,该级联电路能够在85V~450V输入电压范围内稳定工作,并输出稳定的低纹波28V电压。在单电压型控制调压系统中,输入电压变化会引起系统各电气变量变化,只有这些变化引起输出电压的变化之后,电压控制环才起到调节作用。平均电流控制通过引入电感电流构建内反馈环,能更快的反应输入电压变化,从而迅速的调节系统。论文构建了平均电流控制系统作为前级双管BuckBoost变换器的环路控制系统,验证了该控制系统在85V~450V输入电压范围内的适用性;介绍了双管BuckBoost电路的工作原理,并建立了电路两种工作模式的小信号模型;对前级主电路进行详细的参数设计,并讨论其元器件的选取。后级双管正激变换器主要作用是二次降压和电气隔离,同时保证负载变化时输出电压的稳定性,采用单电压环控制系统。建立了双管正激变换器的小信号模型,对主电路参数进行了设计,并对环路控制系统进行了详细的设计。为了确保本文所提出的两级式级联变换器稳定工作,论文分析了前级双管BuckBoost变换器的输出阻抗与后级双管正激变换器的闭环输入阻抗的关系,验证了两者满足级联系统稳定性判据。为验证两级式变换器的可行性以及理论分析的正确性,建立了基于PSIM软件平台的仿真模型。仿真结果表明:系统能稳定工作并具有良好的动静态特性,输入电压变化和负载变化引起的输出电压扰动很小,输出电压近似恒定。最后,制作了两级式变换器的原理样机,并进行了实验研究,对实验所得波形进行了分析,验证了本文所提出方案的可行性和正确性。更多还原

【Abstract】 In real life,input voltage changes of equipments would practically exceed its normal range in certain circumstances. The normal range of input voltage changes of equipments would be practically exceeded in certain circumstances. Instability of the control system may be caused by wide range input voltage, making the stress of electronic devices go beyond of its voltage and current pressure level therefore leading to overheating or damage. Special military vehicles are often faced with the problem of wide range input problem because of its unique application environment. While high stability of input voltage of DC 28V is perfectly required by the internal electronic equipments, sound dynamic performance, small size and high stability are also required by the power modules in special military vehicles. In this paper, a two-stage DC/DC converter solution, cascaded by a dual switch BuckBoost converter and forward converter, is proposed for the wide range input voltage problem in special military vehicles. The input voltage range in 85V~450V permits the steady performance of the cascade system while providing stable and low ripple 28V output voltage.In single voltage control system, the input voltage change bring about changes of other electrical system variables change. Only when the output voltage changes are caused by these variables would the voltage control loop play a regulatory role. Average current control system can response to the input voltage change and adjust system faster through constructing the inductor current feedback loop. In this paper, the average current control system is constructed as the control system of the former dual switch BuckBoost converter, and the applicability of this system in 85V~450V input voltage range is verified. Work principle of the dual switch BuckBoost circuit is introduced, and the small-signal models for the two working modes of the converter are established. The parameters of the main circuit are detailed designed and the selections of its components are discussed.The dual switch forward converter, the later stage of the cascade system, plays a role of step-downing voltage, electrical isolation and also has to maintain the output voltage be stable when the load changes. The single voltage loop control system is selected. The small-signal model of the converter is established. The parameters of the main and the single voltage loop control system are detailed designed.To ensure the stability of the proposed two-stage cascade converter, the relationship of the open-loop and closed-loop output impedance of the former converter and the closed-loop input impedance of the later converter is analyzed. Results show that the stability criteria for cascade system is accorded with the relationship.To prove fesibility of the proposed two stage converter and the correctness of theoretical analysis, a simulation model is established based on PSIM software platform. Simulation results show that the system can work stably with sound dynamic and static characteristics. The output voltage disturbances caused by the input voltage change and load change are little, so the output voltage can be considered as a constant.Finally, a prototype of the two-stage converter is fabricated and experiments is carried out. Experiments waveforms are listed and analyzed, verifying the feasibility and correctness of proposed two stage converter.更多还原