This paper presents a detailed and comprehensive performance comparison between phase-disposition (PD) and phase-shifted (PS) pulse-width-modulation (PWM) schemes. The comparison is carried out in a single-phase, two-...
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ISBN:
(数字)9798350376067
ISBN:
(纸本)9798350376074
This paper presents a detailed and comprehensive performance comparison between phase-disposition (PD) and phase-shifted (PS) pulse-width-modulation (PWM) schemes. The comparison is carried out in a single-phase, two-cell asymmetrical cascaded H-bridge (ACHB) converter that uses DC-voltage sources chosen according to a geometric progression with a factor of two and three. The converter controlled by each PWM method is designed to generate an output voltage waveform with 7 and 9 levels under 2:1 and 3:1 DC voltage ratios, respectively. The paper analyzes the effects of PWM-induced harmonic components of each method on the converter’s output current and voltage waveforms. The comparison is conducted on Typhoon HIL-based real-time simulation and lab prototype experimental results at different operating conditions. The comparative performance includes the spectra and THDs of the converter output voltages and currents, as well as the electromagnetic interference (EMI) noise emission. The single-phase ACHB demonstrates improved harmonic performance and 56% lower THD values when utilizing the PS-PWM technique compared to the PD-PWM method. The PS-PWM method operates at 6 times higher frequency than the PD-PWM method, leading to high switching losses, EMI noise emission, and lower efficiency. In contrast, the PD-PWM method lowers switch stress and reduces switching losses as less heat is generated.
Electromagnetic pulses caused by high altitude nuclear explosions (HEMPs) have the potential to severely disrupt large-scale electric grids. This paper presents some strategies that could be helpful in mitigating the ...
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In this paper, a circularly polarized (CP) substrate-integrated waveguide (SIW)-based H-plane horn antenna with broader impedance bandwidth and higher peak realized gain (PRG) for armature satellite services (X-band, ...
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ISBN:
(数字)9798350369908
ISBN:
(纸本)9798350369915
In this paper, a circularly polarized (CP) substrate-integrated waveguide (SIW)-based H-plane horn antenna with broader impedance bandwidth and higher peak realized gain (PRG) for armature satellite services (X-band, 8–12 GHz) and broadcast satellite (Ku-band, 12–18 GHz) applications is presented. A tapered microstrip transition is used in the feeding section to obtain the broadband characteristics. In addition, the feeding component of the antenna utilizes three quarter-wavetransformers to enhance impedance matching and widen the bandwidth. To generate the CP, two rows of rectangular slots are etched from both the top and bottom metal surfaces of the design. The antenna is designed, fabricated, and tested. The measured fractional impedance bandwidth of 41.6%, the 3-dB axial ratio bandwidth of 3.8 GHz, the maximum PRG of 6.95 dBic, the maximum radiation efficiency (simulated) of 87 %, and the cross-polarization level below -40 dB have been achieved at the center frequency of 13.2 GHz.
Everyone needs to be relaxed in some way. Previous studies show that listening to the combination of musical pieces and natural sounds effectively provide listeners with a relaxed feeling. In this study, we advocate a...
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The poor efficiency of the aluminum gallium nitride (AlGaN)-based ultraviolet (UV)-C light emitting diode (LED) remains as the major hindrance towards its commercialization. Thus, to enhance the internal quantum effic...
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As the penetration of distributed energy resources increases and large conventional generators are retired, voltage regulation of generators and reactive power control of the power system should be considered more car...
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Educational timetabling has long piqued the interest of the scheduling community. Since timetabling governs how universities operate daily, it has been vital in academia to put substantial effort into creating schedul...
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Over the past few years, the use of the Internet for healthcare-related tasks has grown by leaps and bounds, posing a challenge in effectively managing and processing information to ensure its efficient utilization. D...
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A 1.2 kV SiC H-shaped poly-Si gate MOSFET (HPG MOSFET) structure was proposed to effectively reduce switching loss without compromising static device characteristics. The structure features a locally etched poly-Si ga...
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This article uses first-principles DFT computations to present structural properties, electronic band structures and density of states (DOS) in II-(VI) 2 mixed-metal pyrite dichalcogenides Cd x Zn 1-x Te 2 . A small m...
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ISBN:
(数字)9798350357509
ISBN:
(纸本)9798350357516
This article uses first-principles DFT computations to present structural properties, electronic band structures and density of states (DOS) in II-(VI) 2 mixed-metal pyrite dichalcogenides Cd x Zn 1-x Te 2 . A small modification in the crystal structure is observed and it changes from pure cubic to pseudo-cubic depending on the Cd-composition, x. Indirect-to-direct bandgap transition and the presence of double valleys in the conduction band in the electronic band structures are noticed for different Cd-compositions of the Cd x Zn 1-x Te 2 mixed crystal system. Further, metal mixing causes enhancement of bandgap following a huge nonlinear pattern with negative bowing, which is normally unusual. However, high Te contribution is evident in the DOS across all mixing conditions. The flat conduction band profile along with direct bandgap and the high density of energy states lead to a broader absorption spectrum that suggests potential applications of the compounds in photovoltaic and optical devices. The DOS and structural parameters are used to explain the results obtained in the mixed-metal pyrite dichalcogenide Cd x Zn 1-x Te 2 .
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