兆赫兹高效率隔离型DC/DC变流器串联电压源调控方法研究

By inserting a variable voltage source into the high frequency primary side of the transformer in an isolated DC/DC converter, the output tight regulation can be achieved without two cascaded stages. Furthermore, the efficiency is very high at MHz switching frequency. However, there is a compromise between the optimal operating range of the aforementioned regulating method and the rated input voltage range of the HVDC power supply system in the sever system, that leads to the attenuation of efficiency of the power supply system at rated input voltage. In order to conquer this compromise, a new regulation method is proposed in this proposal. A variable voltage source with two terminals is inserted into the DC side. And, the other high frequency ac side is paralleled to the intermediate ac side of the transformer, which is implemented with coupled windings of the transformer. With this proposed method, the compromise between the optimum operating range and the rated input voltage range is traded off; and the output relation is achieved as well. Furthermore, the additional transformer in previous method is eliminated in the proposal, which increase the power density and efficiency, as well. Based on the regulating concept of inserting variable voltage source with two terminals, the derivation and construction law for the methods of inserting voltage source regulation are analyzed thoroughly and comprehensively. Then, more regulation topologies and methods are gotten to match different input voltage ranges and different applications for the MHz DC/DC converters. Finally, the characteristics of the derived topologies and methods are analyzed and provided. Based these characteristics, the most available and high efficiency topologies for different applications are selected; whose steady state and dynamic models will be presented. Also, the optimization methods for these selected candidates are provided.

交流串联可控电压源对输出电压进行调控的高频隔离型DC/DC变流方法，解决兆赫兹DCX的输出调控难题，提高DC/DC转换效率。但是上述DC/DC调控方法存在最佳运行电压区间与数据中心高压直流供电服务器系统额定电压区间不匹配的矛盾，导致额定条件下系统运行效率降低。为了找到适合数据中心高压直流服务器系统的高频高效DC/DC变流方法，本项目研究并揭示了串联电压源调控方法的形成规律，依据形成规律推演出系列串联电压源调控方法，从中找出能够匹配DC/DC系统运行最佳电压区间与直流母线额定电压区间的调控方法，提高系统功率密度和效率。在此基础上，刻画出各种串联电压源调控方法的最优运行区间和轨迹，建立小信号模型，并探索磁元件的高效率、高密度优化设计新方法，为将串联电压源调控方法用于不同电压区间和应用场合提供理论指导。

随着互联网数据中心、5G通信技术、新能源电动汽车等领域耗电量的迅速增加，为了减少能源损耗和电源模块占用的空间，提升电源模块的效率和功率密度至关重要。本项目基于部分能量调整的思想，推演了MHz隔离型DC/DC变流器的系列串联电压源调控方法，使大部分能量经过单级变换器直接高效率传递至负载，仅小部分能量通过主电路和串联可调电压源，完成电压调节功能。利用所提出的推演方法，给出了九种不同的可调DCX (RDCX)变换器拓扑类别，并给出了辅助电压源拓扑选择的要求，可以适应不同应用场景的需求。.在所提出的系列RDCX拓扑基础上，针对多种应用场景对变换器拓扑进行了优化设计。在通信电源和服务器前端整流器应用当中，变换器输出侧电流较大，输入侧长期运行电压上限，电流较小，因此使受控电压源并联在交流侧，串联在较小电流的输入直流侧；而在车载充电器中，输出为电池负载，需要较宽的电压变化范围，此时可将辅助调压源设置为直接串联在输出侧实现能量充分利用。.为了进一步提升RDCX电路的动态性能，针对串联电压源调控方法的具体实施方案进行了小信号建模分析，分析了变换器主电路参数的影响并进行了控制的优化设计，验证了模型的适用性。.为了提升MHz DCX主电路部分在高压运行时的效率，针对DCX器件的导通损耗建立了数学模型，提出了基于低压器件的高效率低共模噪声的模块化DCX电路构造方法。在使用该模块化设计方案的车载充电器RDCX电路中，峰值效率达到了98.2%，相较于传统方案大幅提升。.为了进一步提升变换器的功率密度，提出了一种综合考虑变压器体积和损耗的分析方法和一种基于三维PCB绕组的新型变压器结构，使得变换器空间利用率接近100%，功率密度可达1kW/in3以上。.为了使RDCX在调压时的功率分配设计更加灵活，针对同时具备升压和降压功能的四开关Buck-Boost电路，提出了基于电感电流有效值最小化的优化方法和基于实时数字控制方案的控制策略，使其在实现高效率能量变换的同时消耗了较少的控制器资源。