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Peng, Xu,Yu, Le,Gong, Kaiyue,Liu, Xiaohan,Yang, Guolong,Xu, Jiangjun,Zhou, Chao,Gao, Lixia,Zhu, Xinyu The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.8
An aircraft ground power unit (GPU) can replace the auxiliary power unit (APU) in an aircraft while the aircraft is parked at an airport. Therefore, the problems associated with the oil consumption and air pollution of the APU are solved. However, the GPU is faced with challenges in terms of utilization, power quality, and fault tolerance. Thus, a novel centralized aircraft GPU based on a three-level neutral point clamped cascaded converter (3LNPC-CC) is introduced in this paper to improve utilization and power quality. Furthermore, an evaluation voltage balance strategy is proposed for the DC-port fault tolerance of the 3LNPC-CC. In addition, both the modulation of the phase shift pulse width modulation (PSPWM) and the control of the double closed loop are used in the 3LNPC-CC. A simulation platform including the control, modulation, and fault tolerance of the system is established to verify the feasibility and performance of the proposed GPU. In particular, it is used to evaluate the voltage balance strategy for DC-port faults. Moreover, a prototype of the GPU and relevant experiments are completed to verify the correctness and feasibility of the system and the strategy.
Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures
Xu Peng,Xiaohan Liu,Guolong Yang,Xijun Liu,Lixia Gao,Xinyu Zhu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5
In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.
Xiaohan Liu,Xiao Liang,Kaiyue Gong,Siqi An,Xu Peng,Jun Cai,Xinyu Zhu,Chao Zhou 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8
The three-phase cascaded H-bridge rectifier (CHBR) is widely used in high power and high voltage applications. This paper focuses on the load removed from the DC port of a three-phase CHBR, which can cause single-phase DC-port voltage unbalance issues and three-phases DC-port voltage unbalance issues. This paper proposes a voltage balance control strategy based on negative sequence current injection for three-phase CHBR to deal with the unbalance problem. An individual DC-port voltage control strategy is designed to balance the DC-port voltage in the faulty phase. In addition, a negative sequence current injection control strategy is responsible for balancing the DC-port voltages in the three phase CHBR. The effectiveness and feasibility of the proposed voltage control strategy based on negative sequence current injection is verified by the experimental results.
Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures
Peng, Xu,Liu, Xiaohan,Yang, Guolong,Liu, Xijun,Gao, Lixia,Zhu, Xinyu The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5
In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.
Fuding Zhang,Xu Zhou,Xiaohan Sun 한국광학회 2014 Current Optics and Photonics Vol.18 No.5
An asynchronous optical packet-switching (AOPS) node with load-balancing capability can achieve better performance in reducing the high packet-loss ratio (PLR) and time delay caused by unbalanced traffic. This paper proposes a novel dynamic load-balancing algorithm for an AOPS node with limited buffer and without wavelength converters, and considering the data flow distribution and service levels. By calculating the occupancy state of the output ports, load state of the input ports, and priorities for data flow, the traffic is balanced accordingly. Simulations demonstrate that asynchronous variant data packets and output traffic can be automatically balanced according to service levels and the data flow distribution. A PLR of less than 0.01% can be achieved, as well as an average time delay of less than 0.46 ns.
Illumination promoting biomass production in wastewater treatment for Rubrivivax gelatinosus
Pan Wu,Xiaohan Xu 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6
In order to improve the reuse degree of Rubrivivax gelatinosus (R. gelatinosus) resource in soybean producing wastewater (SPW) treatment, the impacts of diverse illumination strength on R. gelatinosus biomass and organic contaminant abatement were discussed. It was reported that with the best illumination strength (6,000 lux), the production (3,800 mg/L) of biomass was increased by sixty percent of dark group. COD removal and protein removal rate got 85 and 80%. Influence of diverse illumination strength on R. gelatinosus growth were divided into three aspects, including illumination limitation (0−5,000 lux), illumination saturation (5,000−7,000 lux), illumination inhibition (8,000 lux or higher). Meanwhile, at 6,000 lux, bacteriochlorophyll and carotenoids contents, ATP production were increased by 200, 200, 43.9% severally. Appropriate illumination improved ATP production by increasing the generation of bacteriochlorophyll and carotenoids in photosynthesis. Augment of energy production provoked the biomass production and wastewater treatment. Nevertheless, low or high illumination strength was un-advantage for R. gelatinosus growth due to the illumination deficiency or restrian. Moreover, 6,000 lux shortened the treatment time from 96 h to 48 h.
Xinyu Zhu,Xiao Liang,Kaiyue Gong,Xu Peng,Jun Cai,Xiaohan Liu,Chao Zhou,Siqi An,Chao Wu,Pengcheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12
As a vital component of power electronic transformers (PET), the reliability of a cascaded H-bridge rectifier (CHBR) is essential. Therefore, in this paper, a DC-port voltage balance strategy considering DC-port failure is researched to ensure the stable operation of a CHBR. However, if the DC-port voltage balance strategy is adopted to realize the single-phase balance of a CHBR, the three-phase currents become unbalanced. This paper uses a negative sequence control (NSC) strategy that is conducive to balancing DC-port voltage to achieve three-phase current balance. For the DC-port voltage balance, the matrix generation modulation (MGM) algorithm is proposed. In addition, the DC-port voltage balance boundary is analyzed to determine the range of the DC-port voltage balance in the CHBR. A 3-module cascading topology is adopted to demonstrate the MGM algorithm and the NSC strategy. Through experiments, results show the correctness and feasibility of the proposed strategy.
Chen, Ying-Chen,Lin, Chih-Yang,Huang, Hui-Chun,Kim, Sungjun,Fowler, Burt,Chang, Yao-Feng,Wu, Xiaohan,Xu, Gaobo,Chang, Ting-Chang,Lee, Jack C IOP 2018 Journal of Physics. D, Applied Physics Vol.51 No.5
<P>Sneak path current is a severe hindrance for the application of high-density resistive random-access memory (RRAM) array designs. In this work, we demonstrate nonlinear (NL) resistive switching characteristics of a HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based stacking structure as a realization for selector-less RRAM devices. The NL characteristic was obtained and designed by optimizing the internal filament location with a low effective dielectric constant in the HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB> structure. The stacking HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based RRAM device as the one-resistor-only memory cell is applicable without needing an additional selector device to solve the sneak path issue with a switching voltage of ~1 V, which is desirable for low-power operating in built-in nonlinearity crossbar array configurations.</P>