含箝位电感隔离升降压变换器电路拓扑及控制策略研究

发布时间：2018-06-09 21:57

本文选题：隔离升降压变换器 + 宽电压范围　；参考：《北京交通大学》2017年博士论文

【摘要】：目前,太阳能电池、燃料电池、温差电池、蓄电池、超级电容等装置大规模投入使用。由于各装置端口电压在宽范围内变化,对DC-DC变换器工作电压范围要求也逐渐增加,可实现宽范围升降压调节的变换器受到国内外学者的关注。含箝位电感隔离升降压(Isolated buck-boost, IBB)变换器具有输入输出隔离、工作电压范围宽、功率器件软开关等优点,并且此类变换器原边、副边电路均含开关管,箝位电感电流在两端压差作用下线性变化,变换器的电路拓扑和控制策略具有多样性。本文拟针对IBB变换器的电路拓扑及控制策略展开研究工作。目前已有文献提出了一些IBB变换器电路拓扑,也有文献提出了 IBB类变换器拓扑的简单生成方法,但还不太完善。本文基于IBB变换器的基本结构,提出了原边电路单元、副边电路单元的生成规则和生成方法,并提出了 IBB变换器的生成规则。在此基础上,推导出一系列IBB电路拓扑,包括单变压器简单电平型、单变压器复杂电平型、双变压器型、双输入或双输出型IBB变换器。这些电路拓扑涵盖了以前文献所提出的各种电路拓扑,并得到了一些新的IBB变换器电路拓扑。本文还对IBB变换器的电平形式进行分类,可根据实际需要生成相应的变换器拓扑,并提出了适用的控制策略。准双控全桥式IBB变换器的原边为全桥电路,副边为桥臂开关型全桥电路,采用原边、副边三个桥臂之间的双移相控制,可以实现开关管的软开关及全电压范围、全负载范围的调节。为了详细分析双移相控制时准双控全桥式IBB变换器的工作原理,本文列举了各工作模式,并对相应工作区域进行划分,绘制两个控制量与输出电流之间的三维图以反映电路工作情况。在提出优化控制策略之前,本文分析了已有控制策略的控制轨迹,并研究了不同工况下箝位电感的电流峰值与有效值关系,得出可采用箝位电感电流反映变换器效率的结论。依据电感电流峰值最小原则提出了最优控制轨迹,并讨论了准双控全桥式IBB变换器的参数设计方法,最终改善变换器的电磁兼容及轻载效率等性能。为了改善功率器件的软开关特性并改善变换器的轻载效率,本文在定频双自由度控制的基础上增加变频控制,提出了变频三自由度控制策略。基于准双控全桥式IBB变换器进行分析,通过将三个自由度转换为两个变量,简化了分析复杂度。采用箝位电感电流峰值最小的原则判定最优工作点,将变频三自由度的最优工作点求解问题转换为了基于两个分析变量的非线性最优化问题。为了实现IBB变换器在全电压范围、全负载范围的连续平滑调节,并且限定开关频率范围,提出包含变频电流临界模式(boundary current mode, BCM)、定频BCM模式和变频电流断续DCM (discontinuous current mode, DCM)三种模式的全域控制策略。此外,提出了采用变频三自由度控制时IBB变换器的电路参数设计方法。复合式三电平全桥IBB变换器是本文提出的新IBB变换器电路拓扑,原边电路单元由三电平半桥和半桥电路复合而来,可输出五个电平幅值,副边为桥臂开关型全桥电路。该变换器与准双控全桥式IBB变换器相比,原边开关管数目增加,输出电平数增加,控制自由度也增加,可以扩宽IBB变换器的电压工作范围,但是相应的工作原理及控制策略有待研究。在采用定频控制时,复合式三电平全桥IBB变换器包含了三个控制自由度,工作模式较多,分析较复杂。本文将工作模式限定为BCM模式和DCM模式,实现控制量缩减和分析的简化。在此基础上,依据电感电流峰值最小原则求解并提出最优控制轨迹,当输入电压或者负载发生变化时,控制变量可连续调节并维持变换器输出电压的恒定,拓宽了变换器高效率运行的工作电压范围。对于以上三种控制策略,本文分别提出相应的闭环控制策略实现方法,并搭建实验平台进行验证。当输入电压或负载功率连续变化时,三种控制策略均可实现在各个工作模式间的平滑切换,可实现负载功率的全域调节,并且在宽输入范围和宽负载范围内维持较高效率。本文还提出了各个控制策略适用的IBB变换器拓扑类型,以上控制策略均可推广应用于IBB变换器系列拓扑中。
[Abstract]:At present, solar cell, fuel cell, temperature difference battery, battery, supercapacitor and other devices are widely used. Because of the wide range of the voltage of each device's port, the demand for the operating voltage range of DC-DC converter is increasing gradually. The converter with wide range and voltage regulation can be realized by domestic and foreign scholars. The Isolated buck-boost (IBB) converter has the advantages of input and output isolation, wide operating voltage range and power device soft switch, and the original side of the converter and the secondary circuit all contain switch tubes. The clamp inductor current is linearly changed under the pressure difference at both ends. The circuit topology and control strategy of the converter have diversity. This paper intends to study the circuit topology and control strategy of the IBB converter. At present, some IBB converters have been proposed in the literature, and some documents have been proposed for the simple generation of IBB class converter topology, but it is not very perfect. Based on the basic structure of IBB converter, the original side circuit unit and the side circuit single circuit unit are proposed in this paper. The generation rules and generation methods of the element are presented, and the generation rules of IBB converters are proposed. On this basis, a series of IBB circuit topology, including single transformer simple level, single transformer complex level, dual transformer, dual input or dual output IBB converter, is introduced. These circuit topology covers the various previous documents. The topology of the circuit and some new circuit topology of the IBB converter are obtained. This paper also classifies the level form of the IBB converter. The corresponding converter topology can be generated according to the actual needs, and the applicable control strategy is put forward. The original side of the quasi double control all bridge type IBB converter is the full bridge circuit, the vice side is the bridge arm switch type full bridge circuit, and it is adopted. The dual phase shift control between the three bridge arms in the original side and the secondary side can realize the soft switch and full voltage range of the switch tube and the adjustment of the full load range. In order to analyze the working principle of the quasi double controlled full bridge IBB converter in double phase shift control, the work modes are enumerated in this paper, and the corresponding working areas are divided and two control quantities are drawn. In this paper, the control trajectory of the existing control strategy is analyzed, and the relationship between the current peak current and the effective value of the clamp inductor in different working conditions is studied. The conclusion that the clamp inductor current can be used to reflect the efficiency of the converter is obtained. The optimal control trajectory is proposed, and the parameter design method of the quasi double controlled full bridge IBB converter is discussed. The electromagnetic compatibility and the light load efficiency of the converter are improved. In order to improve the soft switching characteristics of the power device and improve the light load efficiency of the converter, this paper increases the constant frequency dual freedom control. The control strategy of frequency conversion three degrees of freedom is proposed. Based on the quasi double controlled full bridge IBB converter, the analysis complexity is simplified by converting three degrees of freedom to two variables. The optimal working point is determined by the principle of minimum current peak of the clamping inductor, and the optimal working point of the variable frequency three degrees of freedom is solved by the optimal working point. In order to solve the nonlinear optimization problem based on two analytical variables, in order to realize the continuous smooth adjustment of the full load range in the full voltage range and limit the frequency range of the switch, the IBB converter includes the frequency conversion current critical mode (boundary current mode, BCM), the fixed frequency BCM mode and the frequency conversion current intermittent DCM (discontinuous current Mo). De, DCM) the total domain control strategy of three modes. In addition, the circuit parameter design method of IBB converter is proposed with frequency conversion three degree of freedom control. The composite three level full bridge IBB converter is a new IBB converter circuit topology proposed in this paper. The original side circuit unit is composed of three level half bridge and half bridge circuit, and can output five levels. Compared with the quasi double controlled full bridge IBB converter, the converter has an increase in the number of primary side switches, the increase of the output level and the increase of control freedom, which can broaden the voltage range of the IBB converter, but the corresponding working principle and control strategy need to be studied. In the use of constant frequency control, The composite three level full bridge IBB converter contains three control degrees of freedom, more mode of work and more complex analysis. In this paper, the work mode is limited to BCM mode and DCM mode, and the reduction of control quantity and analysis is simplified. When the load changes, the control variable can continuously adjust and maintain the constant output voltage of the converter and widen the operating voltage range of the high efficiency of the converter. For the above three control strategies, the corresponding closed loop control strategy implementation method is proposed in this paper, and the experimental platform is set up to verify. When the rate is continuously changed, the three control strategies can realize the smooth switching between the various working modes, realize the full domain adjustment of the load power, and maintain high efficiency in the wide input range and wide load range. This paper also proposes the IBB converter topology type suitable for each control strategy, and the above control strategies can be extended and applied. In the IBB converter series topology.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM46

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