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SHE-PWM Control for A Four-level Hybrid-Clamped Inverter
Mingzhe Wu,Kui Wang,Kehu Yang,Chengran Ma,Yongdong Li 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In this paper, a control strategy for a four-level hybrid-clamped inverter using SHE-PWM is introduced. An algebraic method combining Groebner bases and symmetric polynomials is implemented to obtain the seven switching angles of SHE-PWM. Compared with the widely-used numerical and intelligent methods, it does not need to choose initial values and is able to obtain all the solutions. Moreover, the calculation efficiency is much higher than the existing algebraic methods. The voltage balancing of the DC-link capacitors and flying capacitors can be achieved by selecting proper redundant switching states. Simulation results are presented to confirm the harmonic elimination effect and the validity of this voltage control strategy.
Mingzhe Shia,노세현,김병련,안광찬,박찬우 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
A preliminary study on the heat transfer characteristics of a thermal storage type precooler for a hydrogen charging system was performed. A heat exchanger was designed in the form of a combination of a double-tube type heat exchanger and a shell-and-tube type heat exchanger, and this was compared with the experimental one and CFD analysis. ANSYS FLUENT was applied to simulate the heat transfer and flow.
Mingzhe Hu,Jun Qian 한국물리학회 2014 Current Applied Physics Vol.14 No.1
The phase assemblage, crystal structure evolution and microwave dielectric response of (Ca0.5þxSr0.5x) [(Al0.5Nb0.5)0.5Ti0.5]O3 ceramics (abbreviated as CSANT hereafter) are investigated. Single perovskite solid solution is formed in the CSANT ceramics in Sr-rich composition range of x < 0.05, however, Ca4Ti3O10- type layered perovskite phase begins to segregate after x ¼ 0.05. The CSANT perovskites crystallized in Fm3m cubic symmetry in the composition range of x 0.2, however, as the Ca2þ content in A-site increased, the oxygen octahedral began to be anti-phase tilted at x ¼ 0.1 and the crystal structure transited to P21/n pseudo-orthorhombic space group thereafter. The microwave dielectric response of the CSANT ceramics is elaborately discussed in terms of their crystallographic structure and chemical composition. When sintered at 1500 C for 4 h, a dielectric constant 3 r of 52.5, a Qf product of 28000 GHz and a sf of þ25.4 ppm/C microwave dielectric ceramic can be obtained in the CSANT ceramics at x ¼ 0.3.
MingZhe Shi,김병련,Le Van Cong,박찬우 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11
A preliminary study on the heat transfer characteristics of a thermal storage type precooler for a hyd rogen charging system was performed. A heat exchanger was designed in the form of a combination of a dou ble-tube type heat exchanger and a shell-and-tube type heat exchanger, and this was compared with the experi mental one and CFD analysis. ANSYS FLUENT was applied to simulate the heat transfer and flow.
Mingzhe Chen,Mozaffari, Mohammad,Saad, Walid,Changchuan Yin,Debbah, Merouane,Choong Seon Hong IEEE 2017 IEEE journal on selected areas in communications Vol.35 No.5
<P>In this paper, the problem of proactive deployment of cache-enabled unmanned aerial vehicles (UAVs) for optimizing the quality-of-experience (QoE) of wireless devices in a cloud radio access network is studied. In the considered model, the network can leverage human-centric information, such as users' visited locations, requested contents, gender, job, and device type to predict the content request distribution, and mobility pattern of each user. Then, given these behavior predictions, the proposed approach seeks to find the user-UAV associations, the optimal UAVs' locations, and the contents to cache at UAVs. This problem is formulated as an optimization problem whose goal is to maximize the users' QoE while minimizing the transmit power used by the UAVs. To solve this problem, a novel algorithm based on the machine learning framework of conceptor-based echo state networks (ESNs) is proposed. Using ESNs, the network can effectively predict each user's content request distribution and its mobility pattern when limited information on the states of users and the network is available. Based on the predictions of the users' content request distribution and their mobility patterns, we derive the optimal locations of UAVs as well as the content to cache at UAVs. Simulation results using real pedestrian mobility patterns from BUPT and actual content transmission data from Youku show that the proposed algorithm can yield 33.3% and 59.6% gains, respectively, in terms of the average transmit power and the percentage of the users with satisfied QoE compared with a benchmark algorithm without caching and a benchmark solution without UAVs.</P>