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- 저자 : Ubaid Ahmad (검색결과 3 건)
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Ubaid Ahmad,Honnyong Cha,Nabeel Naseem,Duc-Tuan Do 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Input-parallel output-parallel (IPOP) connected converter system allows the use of low power converter modules for high power applications. In this paper, a reliable integrated current balancing transformer (ICBT) is proposed for the current balancing requirement of IPOP LLC resonant converter modules. The proposed ICBT based IPOP LLC resonant converter modules ensures both input current sharing (ICS) and output current sharing (OCS) in constituent modules, without dedicated controller. The proposed ICBT is basically the resonant inductors of LLC resonant converter modules, coupled to perform the function of current balancing, and also have enough leakage inductance for resonance operation simultaneously. Moreover, the proposed ICBT can significantly reduce the overall magnetic volume, and increase the power density of IPOP LLC resonant converter modules. Magnetic and electrical models of the proposed ICBT have been presented in this paper. To validate the performance of the proposed ICBT based IPOP LLC resonant converter modules, a 2.5 kW hardware prototype has been designed, fabricated and tested successfully.
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Nabeel Naseem,Honnyong Cha,Ubaid Ahmad,Heung-Geun Kim 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In this paper integrated magnetic current balancing (IMCB) cell-based asymmetrically configured Quad-Active-Bridge (QAB) converter is proposed. QAB converter provides high-frequency isolation for a dc-dc stage of solid-state-transformer (SST), as well as provides a modular solution to the SST medium-voltage (MV) dc link. The proposed IMCB cell ensures the current balancing among the three active H-bridges without using any dedicated controller when transferring equal power from MV to low voltage (LV) side. The proposed IMCB cell is the integration of three inductors of the active H-bridges required for power transfer and zero voltage switching (ZVS), which doesn’t require extra magnetic volume. Simulation and experimental results are presented to validate the performance.
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Kamal Shahanawaz,Ain Mohd Fadzil Bin,Ullah Ubaid,Mohammed Abdullahi S. B.,Hussin Roslina,Omar Mohamad Faiz Bin Mohamed,Najmi Fathul,Ahmad Zainal Arifin,Rahman Mohd Fariz Ab,Mahmud Mohd Nazri,Othman Mo 한국전자파학회 2022 Journal of Electromagnetic Engineering and Science Vol.22 No.4
The deployment of the millimeter (mmWave) frequency spectrum by fifth-generation (5G) device-to-device (D2D) wireless networks is anticipated to meet the growing demands for increased capacity. The antenna is regarded of as an important determinant that guarantees the maximum performance of wireless communication. This paper presents a low-profile magneto-electric (ME) dipole antenna for 5G mmWave D2D communication. A single-element quasi-loop radiator was designed to excite horizontal polarization, and a coaxial probe was used to produce vertical polarization. Subsequently, the structure of the radiator was transformed into a two-element quasi-loop an- tenna to achieve an omnidirectional radiation pattern with relatively enhanced gain. A coaxially fed T-junction microstrip element was implemented to equally distribute the signal between the two quasi-loop radiators and attain proper impedance matching. Furthermore, a pair of shorting pins was introduced into the two-element design to maintain the circularly polarized (CP) radiation. The finest values of the axial ratio and |S11| were derived by rigorously optimizing all the geometry parameters. Both single-element and two-element quasi- loop antennas were fabricated and characterized experimentally on the air substrate. The advantage of avoiding a physical substrate is to realize a wide bandwidth, circumvent dielectric losses, and ascertain the maximum gain. The measured and simulated results agree thor- oughly with each other. Stable in-band CP radiation were accomplished, thus confirming an appropriate field vector combination from the coaxial probe and the radiator. The finalized antenna engaged an area of ~7.6λ for operation at 23.9–30.0 GHz with an axial ratio <3 dB, radiation efficiency ~80%, and gain >5 dBic.
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