【作者】 张玥；

【导师】 王政； 李运帷（Yunwei（Ryan）Li）；

【作者基本信息】 东南大学 ， 电力电子， 2020， 博士

【摘要】 双有源桥式直流变换器(Dual-active-bridge DC/DC converter,简称DAB DC/DC converter)具有效率高、软开关、双功率方向等优点,在新能源汽车中具有广泛的应用前景。其中的电流源型双有源桥式直流变换器(Current-fed dual-active-bridge DC/DC converter,简称CF-DAB DC/DC converter)是一种具有低输入电流纹波和直接电流控制能力的拓扑。这种拓扑是新能源汽车中直流变换器的理想解决方案。然而,电流源型双有源桥式直流变换器仍然面临几个具有挑战性的问题:由变压器漏电感造成的电压尖峰问题、电流源型单元侧的环流问题、电感参数补偿问题等。现有的双有源桥式直流变换器调制方案,主要是针对电压源型双有源桥式直流变换器。因此,为进一步提高电流源型双有源桥式直流变换器的控制性能并拓展其应用,本文以该拓扑为研究对象,主要围绕调制策略和控制方法的优化展开研究。论文主要研究内容与创新成果如下:1.针对电流源型双有源桥式直流变换器由变压器漏电感造成的电压尖峰问题,本文提出了一种解耦的双脉冲宽度调制(Decoupled dual-PWM)策略。在无需使用额外的辅助电路情况下,双脉冲宽度调制策略可以对变压器漏电感进行适当的预充电,从而避免由变压器漏电感造成的电压尖峰问题。在轻负载工作情况下,双脉冲宽度调制策略可以有效抑制电流源型单元侧的环流,从而提高变换器在宽负载范围内的效率。双脉冲宽度调制策略可以根据变换器的瞬时输入电感电流,灵活地调整电压源型单元侧开关器件的开通时刻和开通时长。与现有调制策略相比,双脉冲宽度调制策略有效地降低了变压器漏电感电流峰值、电流源型单元侧的环流和相应的损耗。同时,解耦的双脉冲宽度调制策略避免了电流源型单元侧占空比和电流压型单元侧占空比之间的相互耦合,实现了变换器升压比与变压器漏电感、负载条件之间的解耦。这样将会有助于简化后续变换器控制回路的设计。本部分工作详细阐述了该调制策略的设计过程、功耗分析和实现方式。针对所提出的调制策略,本部分工作基于TI TMS320F28335数字信号处理器,实现数字控制,并搭建了无需额外辅助电路的电流源双有源桥式直流变换器的原理样机。本部分工作通过更深入的实验,验证了所提出的调制策略的有效性。2.电流源型双有源桥式直流变换器的电感参数补偿问题目前仍缺少研究。本部分工作的电感参数补偿问题主要是围绕输入电感和变压器漏电感两个对象。针对变压器漏电感的参数差异性和不确定性问题,本部分工作提出一种新的变压器漏电感的参数补偿方法。该方法不需要额外的高精度电流传感器以测量流经变压器漏电感的瞬时电流。针对变压器漏电感的参数差异性问题,该方法提供了灵活调节的映射输出电压,可以根据不同子模块之间变压器漏电感参数的差异性而单独调节。针对变压器漏电感的参数偏移(不确定性)问题,该方法在参数估计的基础上可以进行补偿,从而进一步提高变换器的闭环控制的稳定性,并实现电流源型单元侧环流的抑制和开关器件上电流应力最小化。此外,本部分工作还针对输入电感的参数偏移(不确定性)问题进行深入分析和研究,通过占空比预测控制的方法解决该问题。针对本部分所提出的几种参数补偿方法,本部分工作搭建了输入为并联结构的电流源型双有源桥式直流变换器原理样机。通过更深入的实验,本部分工作验证了所提参数补偿方法的有效性。3.目前,电流源型桥式单元在三端口类型的磁耦合型有源桥式直流变换器中的应用还很有限。其原因主要是由于电流源型桥式单元中变压器漏电感电流换向的问题。针对这一问题,本部分工作提出了一种适用于包含电流源型全桥单元的磁耦合型三端口有源桥式直流变换器的调制策略。该调制策略可以实现变压器漏电感电流的提前换向、电流源型桥式单元开关器件的软开关操作和环流最小化。针对所提出的调制策略,本部分工作搭建了包含电流源型全桥端口的磁耦合型三端口有源桥式直流变换器的原理样机,并通过实验验证了所提调制策略的有效性。4.脉动直流母线调制策略可以最大限度地减小直流母线上电容的容值,从而为利用薄膜电容器代替电解电容器提供可能。本部分工作将电流源型双有源桥式直流变换器的研究扩展至脉动直流母线的场合。本部分工作提出了一种适用于连续脉动直流母线电压的电流源型DC/AC系统的调制策略。在直流母线电压为连续脉动的情况下,该调制策略仍然可以同时实现变压器漏电感电流的提前换向、电流源型桥式单元的开关器件的软开关操作和环流最小化。此外,在负载情况发生变化时,该调制策略同样适用。针对所提出的调制策略,本部分工作搭建了连续脉动直流母线电压的电流源型DC/AC系统的原理样机。通过实验,本部分工作验证了所提调制策略的有效性。更多还原

【Abstract】 IIIDual-active-bridge DC/DC converter(DAB DC/DC converter)has the advantages of high efficiency,soft-switch,dual power direction and so on.It has a wide application prospect in renewable energy vehicles.The current-fed dual-active-bridge DC/DC converter(CF-DAB DC/DC converter)has low input-current ripple and direct current control capability.This topology is an ideal solution for DC/DC converter in renewable energy vehicles.However,the CF-DAB DC/DC converter still faces several challenging problems: voltage spike caused by transformer leakage inductance,circulation current,parameter compensation,etc.The existing modulation schemes of DAB DC/DC converters are mainly aimed at voltage-fed dual-active-bridge DC/DC converters.Therefore,to further improve the control performance of CF-DAB DC/DC converters and expand their applications,this paper takes this topology as the research object,mainly focusing on the optimization of modulation strategy and control method.The main research contents and achievements of this thesis are as follows:1.In view of the voltage spike problem caused by transformer leakage inductance,this paper proposes a decoupled dual pulse-width-modulation strategy(decoupled dual-PWM).Without the need for additional auxiliary circuit,the dual-PWM strategy can pre-charge the leakage inductance of the transformer properly,thus avoiding the voltage spike problem caused by the leakage inductance of the transformer.In light load operation,the dual-PWM strategy can effectively inhibit the circulation current flow on the side of the current source,so as to improve the efficiency of the converter in the wide load range.The dual-PWM strategy can flexibly adjust the turn-on moment of the voltage-fed side switches.Compared with the existing modulation strategies,the dual-PWM strategy can effectively reduce the peak current of the leakage inductor,the circulation current and corresponding losses.At the same time,the decoupled dualPWM strategy avoids the coupling between the duty-cycle on the current-fed side and the duty-cycle on the voltage-fed side,and realizes the decoupling between the boost ratio,the leakage inductance of the transformer and the load conditions.This will simplify the design of the converter control loop.This chapter also introduces the design process,power consumption analysis and implementation of the modulation strategy in detail.This chapter analyzes the influence of parameter deviation of input inductance and leakage inductance of transformer.Aiming at the modulation strategy proposed in this chapter,this chapter realizes digital control based on TI TMS320F28335 DSP,and builds the principle prototype without auxiliary circuit.In this chapter,the effectiveness of the proposed modulation strategy is verified by further experiments.2.The problem of inductance parameter compensation for current-fed dual-active-bridge converters is still lacking in research.The inductance parameter compensation problem mainly revolves around the input inductance and the transformer leakage inductance.Aiming at the problem of parameter difference and uncertainty of transformer leakage inductance,a new parameter compensation method of transformer leakage inductance is proposed in this part.This method does not require additional high precision current sensors to measure the instantaneous current passing through the leakage inductance of the transformer.Aiming at the parameter difference of transformer leakage inductance,this method provides the reflected output voltage which can be adjusted flexibly and separately according to the parameter difference of transformer leakage inductance between different submodules.To solve the problem of parameter deviation(uncertainty)of transformer leakage inductance,this method can compensate based on parameter estimation to further improve the closed-loop control stability of converter and realize the suppression of current source cell side circulation and the minimization of current stress on switching devices.In addition,this part of the work also for the input inductance parameter deviation(uncertainty)in-depth analysis and research,through duty cycle predictive control to solve the problem.Aiming at the parameter compensation method proposed in this part of work,a prototype of current source type dual-active bridge DC converter with parallel input is built in this paper.Through further experiments,the effectiveness of the proposed parameter compensation method is verified.3.At present,the applications of three-port CF-DAB DC/DC converters are limited.The main reason is voltage spike caused by the leakage inductance.To solve this problem,a modulation strategy for threeport CF-DAB DC/DC converter is proposed in this paper.The modulation strategy can realize the advance commutation of the leakage inductance current of the transformer,the soft switching operation and the minimized circulation current.A principle prototype of a magnetically coupled three-port CF-DAB DC/DC converters is built in this paper,and the effectiveness of the proposed modulation strategy is verified by experiments.4.The pulsating-DC modulation strategy can minimize the capacitance of the DC busbar so as to make it possible to use film capacitors instead of electrolytic capacitors.The pulsating-DC modulation strategy also enables the inverter to achieve a lower equivalent switching frequency and a higher DC voltage utilization.In this part,the applications of CF-DAB DC/DC converter with pulsating-DC busbar are studied.This part of the work proposes a modulation strategy for CF-DAB DC/DC converter with pulsating output voltage.Even if the DC bus voltage is continuously pulsating,this modulation strategy can simultaneously realize the advance commutation of the current of transformer leakage inductance,the soft switching operation and the minimization of circulation current.In addition,the modulation strategy is also applicable when the load conditions change.A principle prototype of the CF-DAB DC/DC converter with pulsating output voltage is built in this paper,and the effectiveness of the proposed modulation strategy is verified through further experiments.更多还原