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RISS 인기검색어
- 검색키워드
- 저자 : Zhou Guanyu (검색결과 4 건)
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A Low-Computation Indirect Model Predictive Control for Modular Multilevel Converters
Ma, Wenzhong,Sun, Peng,Zhou, Guanyu,Sailijiang, Gulipali,Zhang, Ziang,Liu, Yong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.
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A Low-Computation Indirect Model Predictive Control for Modular Multilevel Converters
Wenzhong Ma,Peng Sun,Guanyu Zhou,Gulipali Sailijiang,Ziang Zhang,Yong Liu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.
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Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials
Shim, Jaewoo,Bae, Sang-Hoon,Kong, Wei,Lee, Doyoon,Qiao, Kuan,Nezich, Daniel,Park, Yong Ju,Zhao, Ruike,Sundaram, Suresh,Li, Xin,Yeon, Hanwool,Choi, Chanyeol,Kum, Hyun,Yue, Ruoyu,Zhou, Guanyu,Ou, Yunbo American Association for the Advancement of Scienc 2018 Science Vol.362 No.6415
<P><B>Cleaving with a metal handle</B></P><P>Using adhesive tape to pull off monolayers of two-dimensional (2D) materials is now a well-established approach. However, the flakes tend to be micrometer scale, and the creation of multilayer stacks for device application can be challenging and time consuming. Shim <I>et al.</I> show that monolayers of a variety of 2D materials, including molybdenum disulfide and hexagonal boron nitride, can be cleaved from multilayers grown as 5-centimeter-diameter wafers. The multilayer is capped with a nickel layer, which can be used to pull off the entire grown stack. The bottom of the stack is again capped with nickel, and a second round of cleaving leaves the monolayer on the bottom nickel layer. The monolayers could be transferred to other surfaces, which allowed the authors to make field-effect transistors with high charge-carrier mobilities.</P><P><I>Science</I>, this issue p. 665</P><P>Although flakes of two-dimensional (2D) heterostructures at the micrometer scale can be formed with adhesive-tape exfoliation methods, isolation of 2D flakes into monolayers is extremely time consuming because it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits high-throughput production of multiple monolayers of wafer-scale (5-centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wafer. Wafer-scale uniformity of hexagonal boron nitride, tungsten disulfide, tungsten diselenide, molybdenum disulfide, and molybdenum diselenide monolayers was verified by photoluminescence response and by substantial retention of electronic conductivity. We fabricated wafer-scale van der Waals heterostructures, including field-effect transistors, with single-atom thickness resolution.</P>
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Fault Tolerant Strategy of Abnormal Battery Discharge
Guan Yu,Zhou Xingbo,Liu Peng,Zhao Yu 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.6
To solve the problem of abnormal battery discharge in the operation of electric vehicles, a method of fault tolerance based on data driven is proposed. First, based on the relation between transient voltage and the aging degree, battery SOC estimation model is built through LS-SVM method. Then, the fault-tolerant control scheme is put forward, which aims at abnormal discharge of power battery. When known battery exception occurs, the corresponding model control law is implemented to achieve fault tolerance control. When the unknown abnormal battery fault occurs, using dynamic data circulation way, the unknown exception model is rapidly established implementing system fault tolerant control for unknown exception. Finally, the accuracy of the method is verified by the simulation, which shows that this method is good for the fault tolerance of known and unknown faults.
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