A Current-Sharing Method for Interleaved High-Frequency LLC Converter With Partial Energy Phase Shift Regulation

2021 ◽  
pp. 1-1
Author(s):  
Minglong Wang ◽  
Xiaoming Zha ◽  
Shangzhi Pan ◽  
Jinwu Gong ◽  
Wenqiang Lin
Keyword(s):  
Phase Shift ◽  
High Frequency ◽  
Current Sharing ◽  
Partial Energy ◽  
A Current

Проблемы локации источников акустической эмиссии

2021 ◽  
pp. 35-44
Author(s):  
Ю.Г. Матвиенко ◽  
И.Е. Васильев ◽  
Д.В. Чернов ◽  
В.И. Иванов ◽  
С.В. Елизаров
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Tensile Tests ◽  
Threshold Method ◽  
Near Zone ◽  
Speed Dependence ◽  
Partial Energy ◽  
Base Size ◽  
Frequency Components ◽  
Amplitude Level

The accuracy of the location of acoustic emission (AE) sources in the concentrator zones (central holes 5 mm in diameter) located at a distance of 40 mm from the receiving transducers during tensile tests of steel, aluminum alloy and composite flat specimens with dimensions of 550x50x4 mm was evaluated. Calculated speed dependence of propagation of pulses on the level of their amplitude and the partial energy of the high-frequency components of the spectrum is studied. With the threshold method of signal registration, the error in the location of AE event sources arising in the near zone of the receiving transducers at a distance 𝛥L<0.1 m can significantly exceed 10% relative to the base size (B) of the location area, when B<0.5 m. Moreover, with a decrease in the distance 𝛥L<0.05 m, the level of possible error will increase, reaching 20-30% relative to the basic size of the antenna array, when recording pulses with an amplitude level um<60 dB and a fraction of the energy of high-frequency spectrum components not exceeding 10%.

scholarly journals Enhanced Circular Chain Control for Parallel Operation of Inverters in UPS Systems

2020 ◽  
Vol 12 (19) ◽  
pp. 8062 ◽  
Author(s):  
Mahdi Shahparasti ◽  
Mehdi Savaghebi ◽  
Majid Hosseinpour ◽  
Navid Rasekh
Keyword(s):  
Control Structure ◽  
Parallel Operation ◽  
Nonlinear Loads ◽  
Uninterruptible Power Supply ◽  
Loop Control ◽  
Current Sharing ◽  
Circular Structure ◽  
Uninterruptible Power ◽  
Equal Power ◽  
A Current

In this paper, a current sharing method based on the circular chain control (3C) method is proposed for controlling parallel inverters of unequal ratings in uninterruptible power supply (UPS) applications. Due to its circular structure, 3C is one of the most convenient methods which can be used in UPS as well as microgrid systems. However, the conventional 3C control strategy is only applicable to inverters of equal power ratings. The proposed method not only retains the circular structure of the 3C method, but also provides adaptability for the parallel operation of inverters with different power ratings. Moreover, this method adds hot-swap capability to the parallel inverter. A two-loop control structure is used to control the inverters. For proper current sharing, currents of inverters are conveyed in a circular structure with appropriate gains through control links. Simulation and experimental results for linear and nonlinear loads verify the effectiveness of the proposed strategy.

scholarly journals Phase-Shift Optimization in AA/PVA Photopolymers by High-Frequency Pulsed Laser

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1887
Author(s):  
Daniel Puerto ◽  
Sergi Gallego ◽  
Jorge Francés ◽  
Andrés Márquez ◽  
Inmaculada Pascual ◽  
...  
Keyword(s):  
Phase Shift ◽  
High Frequency ◽  
Large Scale ◽  
Pulsed Laser ◽  
Laser Exposure ◽  
Continuous Laser ◽  
Frequency Limit ◽  
Optical Elements ◽  
First Time ◽  
532 Nm

Photopolymers can be used to fabricate different holographic optical elements, although maximization of the phase-shift in photopolymers has been a challenge for the last few decades. Different material compositions and irradiation conditions have been studied in order to achieve it. One of the main conclusions has been that with continuous laser exposure better results are achieved. However, our results show for the first time that higher phase-shift can be achieved using a pulsed laser. The study has been conducted with crosslinked acrylamide-based photopolymers exposed with a pulsed laser (532 nm). The increment of the phase-shift between the pulsed laser and continuous laser exposure is 17%, achieving a maximum phase-shift of 3π radians and a refractive index shift of 0.0084 at the zero spatial frequency limit, where monomer diffusion does not take place. This allows this photopolymer to be used in large-scale manufacturing.

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