LCC谐振变换器的解析建模与分析

发布时间：2018-05-07 10:03

本文选题：谐振变换器 + 断续电流模式　；参考：《华中科技大学》2014年博士论文

【摘要】：高频化运行是电力电子变换器实现高功率密度和高集成度的重要途径。谐振变换器具有良好的软开关优势,可以借助自身电路环境实现器件的零电压开关或零电流开关,有利于降低变换器的损耗。而LCC谐振变换器兼顾了二元件谐振变换器各自的优点,具有抵抗负载开路和短路、兼容变压器寄生参数的能力,是一种常见的用来实现高压直流电源的电路结构。本文分析比较了当前建模方法应对变换器非线性特性的不足和精确建模所需要解决的关键性问题,提出了利用状态空间法迭代求解实现变换器不同电流模式下精确建模及开关特性分析的思路,为变换器的设计和控制提供了较精确的模型基础,主要工作如下：针对LCC谐振变换器在不同频率下的响应特点,分析给出了以逆变桥和整流桥导通方向为依据的谐振变换器拓扑等效的一般性步骤,推导在不同拓扑下系统的状态方程和状态变量的表达式,分析了逆变桥不同结构和谐振元件初始储能对状态变量响应轨迹的影响；分析了开关周期内能量传递的过程,并在稳态电压恒定的基础上提出了谐振回路与负载侧能量平衡的数学描述。针对较低开关频率下的零电流开关运行,研究了LCC谐振变换器在断续电流模式下的工作过程及数学描述：提出了根据输出电压范围判断变换器等效拓扑交替序列的依据。在等效拓扑的状态空间方程基础上,利用迭代法推导了谐振电流、谐振电压及负载侧整流电流与输出电压间的解析表达式。根据该表达式分别推导了谐振电流正负半波持续时间及总响应时长,并提出了满足零电流开关的最优驱动脉宽概念及相应的配置原则；建立了负载与开关频率对输出电压的共同作用关系,分析了串并联电容比对输出电压增益的影响。通过数字仿真和实验的方式验证了解析模型的正确性。针对较高开关频率下的零电压开关运行,研究了LCC谐振变换器在连续电流模式下的工作过程及数学描述：通过驱动信号闭锁时刻与负载整流器导通时刻的相互关系,确定了变换器等效拓扑的交替序列,推导了不同序列下谐振电流和谐振电压的相互作用关系；针对稳定感性运行两种特解情况,求得了开关频率、负载、输出电压增益三者的映射关系,将特解推广到一般情况分别得到了不同交替顺序下变换器的约束方程,给出了以虚拟角度定义域分析为基础的方程求解过程；分析指出了变换器出现连续电流容性运行的原因及条件,提出了严格意义上满足变换器连续电流感性运行的开关频率和负载变化范围；总结归纳了连续电流模式变换器稳态求解的一般性过程,得到了变换器在连续电流模式不同序列下的精确电压增益曲线,分析了开关频率和负载品质因数对增益的影响趋势,验证了所得数学模型具有较高精确度的特点；提出了满足开关器件零电压开关的驱动信号占空比范围,分析了开关频率和负载电阻变化对功率因数的影响。
[Abstract]:High frequency operation is an important way to realize high power density and high integration of power electronic converters. The resonant converter has good soft switching advantages. It can realize the zero voltage switch or zero current switch of the device by its own circuit environment, which is beneficial to reduce the loss of the converter. The LCC resonant converter takes into account the resonant variation of two elements. The advantages of the converter, which have the ability to resist the open and short circuit of the load and the parasitic parameters of the transformer, are a common circuit structure for the high voltage DC power supply. This paper compares and compares the shortcomings of the current modeling method to the nonlinear characteristics of the converter and the key problems to be solved in the precise model building. The state space method is used to solve the precise modeling and switching characteristics analysis in different current modes of the converter, which provides a more accurate model base for the design and control of the converter. The main work is as follows:
In view of the response characteristics of the LCC resonant converter at different frequencies, the general steps of the topology equivalence of the resonant converter based on the direction of the inverter bridge and the rectifier bridge are given. The expressions of state equations and state variables are derived under different topologies, and the initial energy storage of the different structural and harmonious components of the inverter bridge is analyzed. The influence of the state variable response path, the process of energy transfer in the switch period is analyzed, and the mathematical description of the energy balance of the resonant circuit and the load side is put forward on the basis of steady state voltage.
In view of the zero current switching operation under low switching frequency, the working process and mathematical description of the LCC resonant converter in intermittent current mode are studied. The basis for judging the equivalent topological alternating sequence of the converter based on the output voltage range is proposed. On the basis of the state space path of the equivalent topology, the resonant electricity is derived by the iterative method. The analytical expression between the current and the output voltage of the resonant voltage and the load side of the current and the output voltage is derived. According to this expression, the positive and negative half wave duration and the total response time of the resonant current are derived respectively. The concept of the optimal width of the drive width and the corresponding configuration principle for the zero current switch are proposed, and the output voltage of the load and the switching frequency is established. The influence of series parallel capacitance ratio on output voltage gain is analyzed. The correctness of the analytical model is verified by digital simulation and experiment.
In view of the zero voltage switching operation under high switching frequency, the working process and mathematical description of the LCC resonant converter in the continuous current mode are studied. The alternating sequence of the equivalent topology of the converter is determined by the relationship between the time of the driving signal locking and the conduction time of the load rectifier, and the resonant current under different sequences is derived. The relationship between the resonant voltage and the interaction of the resonant voltage is obtained. The mapping relation between the switching frequency, the load and the output voltage gain is obtained for the two special solutions of the stable inductive operation. The special solution is generalized to the general case, and the constraint equations of the converter under the different alternation order are obtained, and Fang Chengqiu based on the domain analysis of the virtual angle is given. The cause and the condition of the continuous current capacitive operation of the converter are pointed out. The switching frequency and the load change range of the continuous current in the converter are strictly satisfied. The general process of steady state solution of the continuous current mode converter is summarized, and the continuous current mode is obtained. The influence trend of the switching frequency and the load quality factor on the gain is analyzed under the precise voltage gain curves under different sequences, and the high precision of the mathematical model is verified. The duty cycle of the driving signal to meet the switching device zero voltage switch is proposed, and the change of the switching frequency and the load resistance change to the power cause is analyzed. The influence of number.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM46

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