A Singular Value Decomposition based Space Vector Modulation to Reduce the Output Common-Mode Voltage of Direct Matrix Converters

Guan, Quanxue,Yang, Ping,Guan, Quansheng,Wang, Xiaohong,Wu, Qinghua The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

Large magnitude common-mode voltage (CMV) and its variation dv/dt have an adverse effect on motor drives that leads to early winding failure and bearing deterioration. For matrix converters, the switch states that connect each output line to a different input phase result in the lowest CMV among all of the valid switch states. To reduce the output CMV for matrix converters, this paper presents a new space vector modulation (SVM) strategy by utilizing these switch states. By this mean, the peak value and the root mean square of the CMV are dramatically decreased. In comparison with the conventional SVM methods this strategy has a similar computation overhead. Experiment results are shown to validate the effectiveness of the proposed modulation method.

A Singular Value Decomposition based Space Vector Modulation to Reduce the Output Common-Mode Voltage of Direct Matrix Converters

Quanxue Guan,Ping Yang,Quansheng Guan,Xiaohong Wang,Qinghua Wu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

Large magnitude common-mode voltage (CMV) and its variation dv/dt have an adverse effect on motor drives that leads to early winding failure and bearing deterioration. For matrix converters, the switch states that connect each output line to a different input phase result in the lowest CMV among all of the valid switch states. To reduce the output CMV for matrix converters, this paper presents a new space vector modulation (SVM) strategy by utilizing these switch states. By this mean, the peak value and the root mean square of the CMV are dramatically decreased. In comparison with the conventional SVM methods this strategy has a similar computation overhead. Experiment results are shown to validate the effectiveness of the proposed modulation method.

An SVD-based SVM with Common-mode Voltage Reduction for Direct Matrix Converters

Quanxue Guan,Xiaohong Wang,Zhuoli Zhao,Lina Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, a new space vector modulation (SVM) strategy is presented to reduce the output common-mode voltage (CMV) for direct matrix converters. This method modifies the traditional singular value decomposition modulation to enable the usage of switch vectors with 120? phase shift, then substitutes two of the corresponding switch states by an orientation switch state which connects every input to one output phase. Since those orientation switch states have zero CMV at the output side of matrix converters, by this mean, not only the peak value but also the voltage transitions of the CMV are decreased dramatically. Besides, the improvement of the modulation can be implemented by some minor modification in software, and thus not additional costs in hardware are needed. imulation results are shown to corroborate the effectiveness of the proposed method. Index Terms?Common-mode Voltage, Matrix Converters, Singular Value Decomposition, Space Vector Modulation

Z-domain modeling of peak current mode control for full-bridge DC-DC buck converters

Wang, Xiaohong,Huang, Qisong,Zhang, Bo,Chen, Di,Guan, Quanxue The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

Traditional local-averaged state-space modeling for peak current mode (PCM) controls fails to explain the subharmonic oscillation phenomenon when the spectrum is higher than half of the switching frequency. To address this problem, this paper presents a small-signal modeling method in the z-domain, and builds a discrete linear model for the current loop of a full-bridge DC-DC converter. This discrete model is converted into a second-order continuous model that is able to represent the system performance with a wider frequency range. A frequency-domain analysis shows that this model can be used to explain the subharmonic oscillations and unstable characteristics. This provides an engineering guideline for the practical design of slope compensation. The effectiveness of the proposed modeling method has been verified by simulation and experimental results with a prototype working in the Buck mode.

Weak magnetic field accelerates chromate removal by zero-valent iron

Feng, Pian,Guan, Xiaohong,Sun, Yuankui,Choi, Wonyong,Qin, Hejie,Wang, Jianmin,Qiao, Junlian,Li, Lina Elsevier 2015 Journal of environmental sciences Vol.31 No.-

<P>Weak magnetic field (WMF) was employed to improve the removal of Cr(VI) by zero-valent iron (ZVI) for the first time. The removal rate of Cr(VI) was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr(VI) concentration and higher pH. Fe2+ was not detected until Cr(VI) was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr(VI) removal rate and that of Fe2+ release rate in the absence of Cr(VI) at pH4.0-5.5. These phenomena imply that ZVI corrosion with Fe2+ release was the limiting step in the process of Cr(VI) removal. The superimposed WMF had negligible influence on the apparent activation energy of Cr(VI) removal by ZVI, indicating that WMF accelerated Cr(VI) removal by ZVI but did not change the mechanism. The passive layer formed with WMF was much more porous than without WMF, thereby facilitating mass transport. Therefore, WMF could accelerate ZVI corrosion and alleviate the detrimental effects of the passive layer, resulting in more rapid removal of Cr(VI) by ZVI. Exploiting the magnetic memory of ZVI, a two-stage process consisting of a small reactor with WMF for ZVI magnetization and a large reactor for removing contaminants by magnetized ZVI can be employed as a new method of ZVI-mediated remediation.</P>

Exploring Flow Characteristics in IPv6: A Comparative Measurement Study with IPv4 for Traffic Monitoring

( Qiang Li ),( Tao Qin ),( Xiaohong Guan ),( Qinghua Zheng ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.4

With the exhaustion of global IPv4 addresses, IPv6 technologies have attracted increasing attentions, and have been deployed widely. Meanwhile, new applications running over IPv6 networks will change the traditional traffic characteristics obtained from IPv4 networks. Traditional models obtained from IPv4 cannot be used for IPv6 network monitoring directly and there is a need to investigate those changes. In this paper, we explore the flow features of IPv6 traffic and compare its difference with that of IPv4 traffic from flow level. Firstly, we analyze the differences of the general flow statistical characteristics and users` behavior between IPv4 and IPv6 networks. We find that there are more elephant flows in IPv6, which is critical for traffic engineering. Secondly, we find that there exist many one-way flows both in the IPv4 and IPv6 traffic, which are important information sources for abnormal behavior detection. Finally, in light of the challenges of analyzing massive data of large-scale network monitoring, we propose a group flow model which can greatly reduce the number of flows while capturing the primary traffic features, and perform a comparative measurement analysis of group users` behavior dynamic characteristics. We find there are less sharp changes caused by abnormity compared with IPv4, which shows there are less large-scale malicious activities in IPv6 currently. All the evaluation experiments are carried out based on the traffic traces collected from the Northwest Regional Center of CERNET (China Education and Research Network), and the results reveal the detailed flow characteristics of IPv6, which are useful for traffic management and anomaly detection in IPv6.

Enhancing the Robustness and Efficiency of Scale-free Network with Limited Link Addition

( Li Li ),( Qing-shan Jia ),( Xiaohong Guan ),( Hengtao Wang ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.5

The robustness of a network is usually measured by error tolerance and attack vulnerability. Significant research effort has been devoted to determining the network design with optimal robustness. However, little attention has been paid to the problem of how to improve the robustness of existing networks. In this paper, we investigate how to optimize attack tolerance and communication efficiency of an existing network under the limited link addition. A survival fitness metric is defined to measure both the attack tolerance and the communication efficiency of the network. We show that network topology reconfiguration optimization with limited link addition (NTRLA) problem is NP-hard. Two approximate solution methods are developed. First, we present a degree-fitness parameter to guide degree-based link addition method. Second, a preferential configuration node-protecting cycle (PCNC) method is developed to do trade-off between network robustness and efficiency. The performance of PCNC method is demonstrated by numerical experiments.