The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/D...The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.展开更多
A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The t...A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.展开更多
GaN （gallium nitride） buck-rectifier has been proposed to realize high power density ISOP （input series and output parallel）-IPOS （input parallel and output series） converter-based dc distribution system. The ul...GaN （gallium nitride） buck-rectifier has been proposed to realize high power density ISOP （input series and output parallel）-IPOS （input parallel and output series） converter-based dc distribution system. The ultra-low loss bi-directional switch can be developed by the GaN power device because of the low on-resistance, the high-speed switching behavior and its own device structure. The buck-rectifier using the GaN bi-directional switches has the potential to achieve higher power density than the commonly utilized boost-rectifier. Availability of the GaN-HEMT （high electron mobility transistor） for the buck rectifier has been verified taking the theoretical limit of the on-resistance and the switching loss energy into account. Design consideration for a high power density buck-rectifier has been also conducted and the application effect of the GaN bidirectional switches has been evaluated quantitatively. The ISOP-IPOS converter-based dc （direct current） distribution system takes full advantage of the buck-rectifier and the rectifier using GaN devices contributes to realizing higher power density dc distribution system.展开更多
The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC vo...The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.展开更多
介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用...介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用范围大的特点,并给出了相应推导过程;给出了输出电压为25 k V,电流为1 A的变换器的分析和谐振参数设计。最后进行了仿真,仿真结果表明,基于高频交流链接并联谐振拓扑和基于状态平面图法的控制能够稳定输出电压(<1%),实现零电流开关,三相输入电流谐波较低(THD<12.5%)与三相电压基本同相位,功率因数为0.99。展开更多
基金supported by National Key Research and Development Program of China (2016YFB0900500,2017YFB0903100)the State Grid Science and Technology Project (SGRI-DL-F1-51-011)
文摘The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.
文摘A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.
文摘GaN （gallium nitride） buck-rectifier has been proposed to realize high power density ISOP （input series and output parallel）-IPOS （input parallel and output series） converter-based dc distribution system. The ultra-low loss bi-directional switch can be developed by the GaN power device because of the low on-resistance, the high-speed switching behavior and its own device structure. The buck-rectifier using the GaN bi-directional switches has the potential to achieve higher power density than the commonly utilized boost-rectifier. Availability of the GaN-HEMT （high electron mobility transistor） for the buck rectifier has been verified taking the theoretical limit of the on-resistance and the switching loss energy into account. Design consideration for a high power density buck-rectifier has been also conducted and the application effect of the GaN bidirectional switches has been evaluated quantitatively. The ISOP-IPOS converter-based dc （direct current） distribution system takes full advantage of the buck-rectifier and the rectifier using GaN devices contributes to realizing higher power density dc distribution system.
基金This work was supported in part by the National Nature Science Foundation of China(51977142)。
文摘The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.
文摘介绍了一种基于AC-link技术的并联谐振高压电源的拓扑电路,该结构结合准谐振的工作模式能够实现高功率因数和高效率;采用了基于状态平面图对并联谐振电路的分析方法,该方法相比传统的基波等效分析法具有求解简单、直观、精确和负载适用范围大的特点,并给出了相应推导过程;给出了输出电压为25 k V,电流为1 A的变换器的分析和谐振参数设计。最后进行了仿真,仿真结果表明,基于高频交流链接并联谐振拓扑和基于状态平面图法的控制能够稳定输出电压(<1%),实现零电流开关,三相输入电流谐波较低(THD<12.5%)与三相电压基本同相位,功率因数为0.99。
