基于电压自适应层叠式能效优化的宽增益范围AC/DC变换方法与关键技术研究

Two-stage AC/DC power converters with wide voltage range on the DC-side are widely applied in various power systems, such as electric-vehicle chargers, energy storage system, renewable power systems and the like. It is difficult for the conventional two-stage AC/DC power converters to achieve high conversion efficiency within the entire operation range when the DC-side voltage varies in a wide range. The performance of the conventional two-stage AC/DC power converter is affected greatly by the DC-side voltage regulation range. According to the instantaneous value of the AC input voltage, the pulsating input power of the AC/DC converter will be divided into two parts and processed optimally by building multiple power flow paths. Novel multi-DC-port rectifiers with multiple power paths and stacked energy-efficiency optimization principles will be proposed. The DC output voltage of the multi-DC-port rectifier will be adaptively matched with the DC voltage on the load side. Hence the load-side DC voltage can be directly regulated by the front-end rectifier, rather than regulated only by the second-stage DC/DC converter. As a result, the voltage regulation range of the second-stage DC/DC converter can be narrowed significantly. With the proposed stacked energy-efficiency optimization and voltage adaptive matching methods, high efficiency AC/DC power conversion within wide DC voltage range will be achieved. This work will propose and study: (1) circuit architecture of novel two-stage AC/DC power converters based on voltage adaption and stacked energy efficiency optimization; (2) the mechanism and systematic realization methods for novel multi-DC-port rectifier topologies; (3) design criterion of key parameters and optimized modulation strategies considering high efficiency and power constraint of power ports simultaneously; (4) the coordinated operation and control methods of the multi-DC-port rectifiers and DC-DC converters. The research results will provide new methods and key technologies for AC/DC power converters with wide DC-side voltage range. Based on the above works, the issue that can't achieve high conversion efficiency within a wide DC voltage range will be solved. The research results will provide key technical support for the large-scale application of electric-vehicle and energy storage system in the future.

电动汽车充电、储能等直流侧电压宽幅变化的系统中，难以在全电压范围内实现高效率是影响两级式AC/DC变换器系统性能和经济性的主要难题。拟将变换器交流侧脉动功率根据交流电压瞬时大小分区处理，针对不同电压区间分别构建高效功率通路，提出基于多功率通路层叠式优化的多直流端口整流器；通过使多直流端口整流器的直流输出电压与负载侧电压自适应匹配，直接利用整流器实现负载电压的宽幅调节，大大减小后级直流变换器电压增益调节范围，实现宽直流电压范围高效电能变换。拟研究并提出：电压自适应匹配层叠式能效优化的AC/DC变换器电路结构；多直流端口整流器电路拓扑构造机理及其系统实现方法；兼顾高效率和端口功率约束的调制策略和关键参数设计准则；多直流端口整流器与直流变换器协同运行控制技术。项目成果将解决直流侧电压宽幅变化时变换器无法兼顾电压调节范围和变换效率的关键问题，为未来电动汽车、储能系统的规模化应用提供关键技术支撑。

电力变换技术是国防、储能和新能源等领域的核心技术，交流和直流电能之间的相互变换是最典型的功率变换形式之一。实现超宽电压范围高效、轻量化供电，是提高电源系统环境适应能力、系统性能和经济性的关键。该项目解决了宽电压增益范围调控与高效率、轻量化、高可靠电力变换之间不可调和的矛盾，在宽增益交直流电力变换拓扑结构及其多自由度调控方法、多变换器组合系统宽增益调控与高效可靠协同控制等方面突破了多项关键技术，解决了交直流电源系统中宽增益电压调控与全工作范围高性能电力变换无法兼顾的共性难题。具体工作如下：研究了基于多端口交直流变换器和多功率通路能效优化方法的宽直流电压范围AC-DC变换方法，提出了多功率通路层叠式能效优化的交直流电能变换新架构，以及利用AC/DC变换器实现直流侧电压宽范围调节的新方法；发明了适用于不同应用场合的多直流端口整流器拓扑结构，以及以多直流端口整流器为基础的非隔离型、隔离型、电压叠加型、电流叠加型等不同形式的组合式电源系统，解决了新型组合式架构变换器调制、功率分配以及多变换器组合式协同运行等关键技术；将所提出的多功率通路层叠式能效优化整流器结构进一步发展，提出了多直流端口单相和三相双向AC/DC变换器、双Buck逆变器等多种新型高效交直流变换器电路拓扑，并在此基础上开展了控制调制、设计实现等关键技术的研究。研制了多台实验样机，进行了充分的实验研究，实验测试结果表明所提出的解决方案能够在拓宽电压调节范围的同时实现更优的效率，表明了所提方法的有效性。相关成果已推广应用于电动汽车、储能系统、电能质量治理、新能源发电等场合。研究成果发表高水平论文30余篇，授权发明专利5项，获江苏省优秀硕士学位论文1篇、中国电源学会优秀学术论文1篇。相关成果作为重要支撑获江苏省科学技术二等奖1项，项目负责人获中国电源学会科学技术奖优秀青年奖。