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Research on Dual-Operation Mode of 3-Level LLC Resonant Converter
A. Zhenwei Li,B. Lei Zhao,C. Yuan Liu,D. Haoyu Li 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In order to meet the demands of high efficiency and a wide adaptable range of input voltage, a Dual- Operation Mode half-bridge LLC converter which can operate in two different modes according to the level of input voltage is obtained by adjusting the driving control strategy of 3-level LLC resonant converter, and the adaptable range of input voltage is doubled with the same parameters of resonant tank. The limiting factors on adaptable range of input voltage are defined by analyzing the voltage gain characteristic and power loss of LLC converter. After analyzing the Dual-Operation Mode of 3- level LLC converter and its influence on the adaptable range of input voltage, the driving control strategy is defined. The characteristic about wide input adaptability and high efficiency of the Dual-Operation Mode half-bridge LLC converter are verified through simulation and experiments.
Li, Yuanming,Yuan, Pan,Ren, Quan-yao,Su, Guanghui,Yu, Hongxing,Wang, Haoyu,Zheng, Meiyin,Wu, Yingwei,Ding, Shurong Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.5
The plate-type fuel assembly adopted in nuclear research reactor suffers from complicated effect induced by non-uniform irradiation, which might affect its stress conditions, mechanical behavior and thermal-hydraulic performance. A reliable numerical method is of great importance to reveal the complex evolution of mechanical deformation, flow redistribution and temperature field for the plate-type fuel assembly under non-uniform irradiation. This paper is the first part of a two-part study developing the numerical methodology for the thermal-fluid-structure coupling behaviors of plate-type fuel assembly under irradiation. In this paper, the thermal-fluid-structure coupling methodology has been developed for plate-type fuel assembly under non-uniform irradiation condition by exchanging thermal-hydraulic and mechanical deformation parameters between Finite Element Model (FEM) software and Computational Fluid Dynamic (CFD) software with Mesh-based parallel Code Coupling Interface (MpCCI), which has been validated with experimental results. Based on the established methodology, the effects of non-uniform irradiation and fluid were discussed, which demonstrated that the maximum mechanical deformation with irradiation was dozens of times larger than that without irradiation and the hydraulic load on fuel plates due to differential pressure played a dominant role in the mechanical deformation.
Li, Yuanming,Ren, Quan-yao,Yuan, Pan,Su, Guanghui,Yu, Hongxing,Zheng, Meiyin,Wang, Haoyu,Wu, Yingwei,Ding, Shurong Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.5
The plate-type fuel assembly adopted in nuclear research reactor suffers from complicated effect induced by non-uniform irradiation, which might affect stress conditions, mechanical behaviors and thermal-hydraulic performance of the fuel assembly. This paper is the Part II work of a two-part study devoted to analyzing the complex unique mechanical deformation and thermal-hydraulic characteristics for the typical plate-type fuel assembly under irradiation effect, which is on the basis of developed and verified numerical thermal-fluid-structure coupling methodology under irradiation in Part I of this work. The mechanical deformation, thermal-hydraulic performance and Mises stress have been analyzed for the typical plate-type fuel assembly consisting of support plates under non-uniform irradiation. It was interesting to observe that: the plate-type fuel assembly including the fuel plates and support plates tended to bend towards the location with maximum fission rate; the hot spots in the fuel foil appeared at the location with maximum thickness increment; the maximum Mises stress of fuel foil was located at the adjacent location with the maximum plate thickness increment et al.
Fuwei Li,Jie He,Peng Luo,Haoyu Jiang,Mingxin Liu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4
This paper presents a quadratic-type high step-up DC–DC converter for renewable energy applications with a continuousinput current. To reduce the number of components while increasing the gain, a quadratic boost converter and two multiplier cells are applied as the primary and secondary circuit with one coupled inductor connected. In addition, the clamp circuit shares its components with both the second boost stage and the voltage multiplier, which increases the power density. As a result, the leakage energy is recycled and the voltage stress can be suppressed. The operation principles and steady-state analyses including loss analysis of the proposed converter are addressed in detail. Compared with relevant existing topologies of quadratic converter, the proposed converter performs a higher voltage gain and a lower power switch stress. To validate the performance, a 200 W experimental prototype is constructed and tested with 20 V of input voltage and 400 V of output voltage, where the highest efficiency is 95.2% and the full-load efficiency is 93.7%. The performance under dynamic conditions is also verified. In the end, an improved topology based on the proposed converter is supplemented.
Robust Model Predictive Control for Uncertain Positive Time-delay Systems
Junfeng Zhang,Haoyue Yang,Miao Li,Qian Wang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.2
This paper proposes the robust model predictive control of positive time-delay systems with interval andpolytopic uncertainties, respectively. The model predictive control framework consists of linear constraint, linearperformance index, linear Lyapunov function, linear programming algorithm, and cone invariant set. By virtue ofmatrix decomposition technique, robust model predictive controllers of interval and polytopic positive systems withmultiple state delays are designed, respectively. A multi step control strategy is utilized and a cone invariant set isconstructed. Linear programming is used for the corresponding MPC conditions. Finally, a numerical example isgiven to verify the effectiveness of the proposed design.
Wu Zhigang,Li Weili,Tang Haoyue,Luo Shifan,Zhang Liangliang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6
In order to adapt the development demand of electric vehicle (EV) drive motor with high power density, high-speed motor is an inevitable trend. There have been numerous studies on the optimisation of cooling structures and losses in high-speed motor, but little has been said about the mechanism of heat transfer problems. Especially in the context of diverse driving scenarios and high-speed drive for EVs, it is crucial to study the differences in heat transfer mechanisms between high-speed motors and normal-speed motors. The research work is based on a principle prototype with a maximum speed of 50 kW-30,000 rpm. A dynamic calculation method is proposed for the rotor’s convective heat transfer coefficient (CHTC) over a wide speed range and multiple scenarios. This method has the advantages of simplicity and high efficiency in calculating the CHTC of rotor, and avoids the complex preprocessing and difficult convergence problems of the fluid–solid coupling calculation. Finally, the accuracy of the calculation results is verified by the temperature rise test of the high-speed motor.
Xichang Wang,Haoyu Wang,Li Yan,Lihui Yang,Yuanming Xue,Jing Yang,Yongli Yao,Xulei Tang,Nanwei Tong,Guixia Wang,Jinan Zhang,Youmin Wang,Jianming Ba,Bing Chen,Jianling Du,Lanjie He,Xiaoyang Lai,Yanbo Li 대한내분비학회 2021 Endocrinology and metabolism Vol.36 No.4
Background: Subclinical hypothyroidism (SCH) is the most common thyroid dysfunction, and its relationship with blood pressure(BP) has been controversial. The aim of the study was to analyze the association between SCH and newly-diagnosed hypertension. Methods: Based on data from the Thyroid disease, Iodine nutrition and Diabetes Epidemiology (TIDE) study, 49,433 euthyroid individuals and 7,719 SCH patients aged ≥18 years were enrolled. Patients with a history of hypertension or thyroid disease were excluded. SCH was determined by manufacturer reference range. Overall hypertension and stage 1 and 2 hypertension were diagnosedaccording to the guidelines issued by the American College of Cardiology/American Heart Association in 2017. Results: The prevalence of overall hypertension (48.7%), including stage 1 (28.9%) and 2 (19.8%) hypertension, increased significantly in SCH patients compared with euthyroid subjects. With elevated serum thyroid stimulating hormone (TSH) level, the hypertension prevalence also increased significantly from the euthyroid to different SCH subgroups, which was more profound in femalesor subjects aged <65 years. The age- and sex-specific regression analysis further demonstrated the same trends in the general population and in the 1:1 propensity matched population. Similarly, several BP components (i.e., systolic, diastolic, and mean arterial BP)were positively associated with TSH elevation, and regression analysis also confirmed that all BP components were closely relatedwith SCH in female subjects aged <65 years. Conclusion: The prevalence of hypertension increases for patients with SCH. SCH tends to be associated with hypertension and BPcomponents in females younger than 65 years.
Lei Zhao,Haoyu Li,Yanxue Yu,Yutian Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
The main theme of this paper is to propose a novel peak current mode control method to reduce the loss of phase-shifted full-bridge (PSFB) converter under light load condition. The proposed control method can adjust the switching frequency of the converter to keep the on-time of switches fixed. According to the loss analysis model in discontinuous current mode operation, the switching frequency is proportional to load current and the efficiency is independent from the load. Moreover, the small signal model of the PSFB converter with the proposed control method is presented. A digital-controlled experimental system is set up. The proposed method is investigated and confirmed by experimental results. Experimental results show that the efficiency and dynamic performance can be improved. These results confirm the effectiveness of the proposed control method.