基于H桥拓扑大容量变流器的若干关键技术研究

发布时间：2018-04-08 13:36

本文选题：H桥　切入点：死区　出处：《浙江大学》2014年博士论文

【摘要】：大规模开发使用可再生新能源、电动汽车、电力机车可以在一定程度上缓解化石能源的日益短缺以及消耗传统能源带来的环境恶化问题。大容量变流器是规模化新能源电力系统、电动汽车驱动系统、电力机车牵引传动系统的核心部件,与它相关的关键技术问题包括电能质量问题、拓扑结构、并联技术与多电平技术。本文围绕这些关键技术问题,在总结、归纳当前研究现状和技术发展的基础上,主要对以下几个方面进行深入研究：共直流母线并联逆变器系统(PIS)的运行方式、前级级联后级并联型模块化AC-DC-DC变换器拓扑结构以及运行方式、H桥死区消除正弦脉宽调制(SPWM)、六半桥(3H桥)逆变器电路拓扑及其死区消除空间电压矢量脉宽调制(SVPWM)等。首先,论文针对适用于大容量并网逆变器或是不间断电源(UPS)的共直流母线PIS的拓扑结构提出了理想无环流运行方式。本文为UPS用共直流母线PIS输出端建立数学模型,并且设计了两种包含电压外环以及电流内环的双闭环控制方法。另外,详细分析了信号传输延时引起各并联单元之间的环流,并提出了相应的解决措施。其次,论文针对适用于将交流高压变换为直流低压的前级级联后级并联型模块化AC-DC-DC变换器,讨论了输出均流与前级输入均压之间的约束关系,并且理论分析与实验验证了前级级联型PWM整流器输入输出均压与前级各直流输出端等效电阻之间关系,从而得出一个能同时满足后级输出均流与前级输入输出均压的方案。同时,论文提出了前级级联PWM整流器与后级DC-DC并联系统的控制方法。再次,论文基于H桥拓扑结构提出了用于每个开关周期内能够改变同一桥臂上下开关管互补导通的新型开关策略。利用新型开关策略的特点,提出了死区消除SPWM方案,并对方案中的关键点即如何精确判断逆变器输出电流极性做了详细的介绍。死区消除SPWM能够被应用于共直流母线PIS以及级联PWM整流器中。最后,论文借鉴单相全桥逆变器相对于半桥逆变器的优势,将三半桥三相逆变器改造为3H桥三相逆变器。虽然3H桥逆变器中的开关管承受的电压电流应力与三半桥逆变器相同,但是在直流侧电压相同的情况下,3H桥逆变器相比三半桥逆变器输出的最大功率提高了一倍,具有扩容效果。针对3H桥三相逆变器的拓扑结构,提出了与之匹配的死区消除SVPWM方案,并为其输出端口设计了直接驱动负载与采用工频隔离变压器阻断零序电流流通的两种接线方式。
[Abstract]:The large-scale development and use of renewable new energy, electric vehicles and electric locomotives can to some extent alleviate the increasing shortage of fossil energy and the deterioration of the environment caused by the consumption of traditional energy.Large capacity converter is the core component of large-scale new energy power system, electric vehicle driving system and electric locomotive traction drive system. The key technical problems related to it include power quality problem, topology structure, and so on.Parallel technology and multilevel technology.On the basis of summing up the current research situation and the development of technology, this paper focuses on the following aspects: the operation mode of the common DC busbar parallel inverter system (PISs).The topology and operation mode of the former cascaded hind parallel modular AC-DC-DC converter are used to eliminate the sinusoidal pulse width modulation (SPWM), the six-half bridge / 3H) inverter topology and its dead-time elimination space voltage vector pulse width modulation (SVPWM).Firstly, this paper proposes an ideal non-circulation operation mode for the topology of a common-DC busbar PIS for large capacity grid-connected inverters or uninterruptible power supply (ups).In this paper, a mathematical model is established for UPS with a common DC bus PIS output, and two kinds of double closed loop control methods including voltage outer loop and current inner loop are designed.In addition, the circulation between parallel units caused by signal transmission delay is analyzed in detail, and the corresponding solutions are put forward.Secondly, this paper discusses the constraint relationship between output current sharing and input voltage sharing for the former cascade and rear stage parallel modular AC-DC-DC converter, which is suitable for converting AC high voltage to DC low voltage.The theoretical analysis and experiment verify the relationship between the input and output voltage of the cascade PWM rectifier and the equivalent resistance of each DC output end of the former stage. Thus, a scheme that can satisfy the current sharing of the back stage and the input and output voltage of the previous stage is obtained.At the same time, the paper presents the control method of the former cascade PWM rectifier and the rear stage DC-DC parallel system.Thirdly, based on the H-bridge topology, a novel switching strategy is proposed, which can change the complementary conduction of the upper and lower switches of the same arm in each switching cycle.Based on the characteristics of the new switching strategy, a dead-time elimination SPWM scheme is proposed. The key point of the scheme is how to accurately judge the polarity of the output current of the inverter.Dead-time cancellation SPWM can be used in common DC bus PIS and cascade PWM rectifier.Finally, using the advantage of single-phase full-bridge inverter compared with half-bridge inverter, the three-half-bridge three-phase inverter is transformed into 3H-bridge three-phase inverter.Although the voltage and current stress of the switching tube in the 3H bridge inverter is the same as that of the tri-bridge inverter, the maximum output power of the 3H bridge inverter is doubled compared with that of the tri-half-bridge inverter under the same DC voltage.The utility model has the effect of capacity expansion.Aiming at the topology structure of 3H bridge three-phase inverter, a matched dead-time elimination SVPWM scheme is proposed, and two connection modes of direct driving load and blocking zero sequence current flow with power frequency isolation transformer are designed for its output port.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM46

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