基于通用开关耦合电感单元的PWM型高变比DC/DC变换器建模方法研究

High step-up dc/dc converters are widely used in renewable energy applications. Compared with traditional dc/dc converters, many of high gain converters are more complicatedly structured and controlled. Therefore the modeling process, characterized by multiple state variables, high order, and multiple working states, is very difficult, which hindered the development of high gain converters. In this project, we proposed a new unified nonlinear modeling block——Tapped Inductor Switcher (TIS), which can significantly simplify the modeling task of complicated integrated dc/dc converters. Moreover, with considering the leakage inductance in the non-ideal TIS block, the effect on dynamic characteristics of high step-up dc/dc converter caused by the leakage energy redirection is going to be studied. The physical and mathematical relationship between voltage and current state variables will be revealed based on analyzing and calculating the inductor current ripple and capacitor voltage ripple. Accordingly new full order dynamic model with high accuracy can be obtained which overcomes the frequency domain limitation of traditional averaged modeling methods. The proposed new unified modeling method can build the firm foundation for studying high step-up dc/dc included contemporary converters and power electronics system.

高变比DC/DC变换器在新能源领域应用广泛。与传统变换器相比，该类拓扑具有更复杂的结构和控制方式，其建模过程具有多状态变量、多模态、高阶等特点。相关建模技术是应用高变比变换器的基础和难点，有重要研究价值。本项目采用统一耦合电感模型构造新型通用建模组件（Tapped Inductor Switcher——TIS），可有效简化复杂拓扑的建模过程。同时通过在TIS组件内考虑耦合电感的漏感，重点研究漏感能量传导方式对高变比变换器动态特性的影响规律。通过对电感电流纹波和电容电压纹波的分析计算，揭示漏感及其软开关工作过程中电压、电流状态变量之间的物理关系，拓展传统平均建模法的频域分析范围，建立具有更高精度的全阶电路模型。该项目所提出的建模方法可为包括高变比DC/DC变换器在内的各种电力电子变换器以及大型电力电子系统的建模和控制打下坚实的理论基础，有重要的研究意义。

本项目根据高变比直流变换器拓扑构造规律，提出了基于耦合电感开关模块新型通用非线性建模组件（Tapped Inductor Switcher——TIS）。该技术方案可在保持较高精度的前提下，有效简化PWM型高变比直流变换器建模过程。项目从经典直流变换器及其耦合电感、变压器衍生拓扑着手，提出了感性元件的统一表达模型。在此基础上推演得到适用于复杂高阶拓扑的通用建模组件GTIS，并完成了其电流连续(CCM)和电流断续(DCM)工况下的建模，实验结果表明所提出的DCM建模法频带宽度可达开关频率的1/2。接着重点研究了漏感对高变比变换器动态特性的影响，完成了有损缓冲电路以及基于漏感和电荷泵的无损软开关电路的建模。为提高模型精度考虑了电感电流纹波和器件寄生电阻等参数，为简化建模过程采用了状态平面分析法。应用案例及实验结果表明所提出的建模法对含有损缓冲电路变换器，其稳态模型误差小于5%，小信号模型在1/2开关频率范围内有很高精度；对于无损软开关电路其模型有效频带宽度可达1/3开关频率。.除此以外，项目还拓展性地研究了通用TIS建模法在开关电感变换器上的应用技术方案，通过大量应用案例验证了该方法的正确性和广泛适用性。最后在Matlab/simulink中设计完成了基于通用建模组件（TIS模块族）的可编程建模工具包。通过大量应用案例，给出了该建模工具的使用方法并检验了其正确性。.该项目探索了高变比直流变换器的精确化建模问题，通过将复杂但精确的模型预先封装，解决了建模精确性和复杂性之间的矛盾，所提出的通用建模法应用便捷、精度高、适用性广，基于理论分析成果所开发的建模工具具有教学和工程应用价值。