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Chunjie Li,Guifeng Wang,Fei Li,Hongmei Li,Zhenglong Xia,Zhan Liu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4
This paper proposes a fault-tolerant control strategy with finite control set model predictive control (FCS-MPC) based onhierarchical optimization for five-level H-bridge neutral-point-clamped (5L-HNPC) inverter-fed induction motor drives. Faulttolerantoperation is analyzed, and the fault-tolerant control algorithm is improved. Adopting FCS-MPC based on hierarchicaloptimization, where the voltage is used as the controlled objective, called model predictive voltage control (MPVC), the postfaultcontroller is simplified as a two layer control. The first layer is the voltage jump limit, and the second layer is the voltagefollowing control, which adopts the optimal control strategy to ensure the current following performance and uniqueness of theoptimal solution. Finally, simulation and experimental results verify that 5L-HNPC inverter-fed induction motor drives havestrong fault tolerant capability and that the FCS-MPVC based on hierarchical optimization is feasible.
Fault-tolerant analysis of two boost inverters for open-end winding induction motor drives
Li, Chunjie,Wang, Guifeng,Li, Hongmei,Li, Fei,Xia, Zhenglong,Liu, Zhan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.4
An open-end winding induction motor drive system fed by two boost inverters with fault-tolerant capability is presented to improve the reliability and safety of the drive system. The boost inverters consist of an impedance-source network and a two-level inverter. It can realize the boost/buck function. An analysis of its fault-tolerance is presented in detail. Short circuits and open circuits are commonly considered as the two main types of faults. Therefore, the fault types of the dual boost inverters are analyzed and diagnosed. Then, two different fault-tolerant schemes are presented. The presented fault-tolerant inverters are restructured through the power switch itself. In addition, different SVPWM methods are addressed. A simulation model and an experimental platform are constructed. Simulation and experimental results verify the fault tolerance of the drive system.
Li, Chunjie,Wang, Guifeng,Li, Fei,Li, Hongmei,Xia, Zhenglong,Liu, Zhan The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4
This paper proposes a fault-tolerant control strategy with finite control set model predictive control (FCS-MPC) based on hierarchical optimization for five-level H-bridge neutral-point-clamped (5L-HNPC) inverter-fed induction motor drives. Fault-tolerant operation is analyzed, and the fault-tolerant control algorithm is improved. Adopting FCS-MPC based on hierarchical optimization, where the voltage is used as the controlled objective, called model predictive voltage control (MPVC), the postfault controller is simplified as a two layer control. The first layer is the voltage jump limit, and the second layer is the voltage following control, which adopts the optimal control strategy to ensure the current following performance and uniqueness of the optimal solution. Finally, simulation and experimental results verify that 5L-HNPC inverter-fed induction motor drives have strong fault tolerant capability and that the FCS-MPVC based on hierarchical optimization is feasible.
A NOTE ON CUBICALLY HYPONORMAL WEIGHTED SHIFTS
Li, Chunji,Cho, Muneo,Lee, Mi Ryeong Korean Mathematical Society 2014 대한수학회보 Vol.51 No.4
In this paper, we show that any cubically hyponormal weighted shift with first two equal weights is flat. And we give an example of a weighted shift which is not cubically hyponormal but almost-cubically hyponormal.
Estimating the domain of attraction via moment matrices
Chunji Li,유천성,Ning Li,Lili Cao 대한수학회 2009 대한수학회보 Vol.46 No.6
The domain of attraction of a nonlinear differential equations is the region of initial points of solution tending to the equilibrium points of the systems as the time going. Determining the domain of attraction is one of the most important problems to investigate nonlinear dynamical systems. In this article, we first present two algorithms to determine the domain of attraction by using the moment matrices. In addition, as an application we consider a class of SIRS infection model and discuss asymptotical stability by Lyapunov method, and also estimate the domain of attraction by using the algorithms. The domain of attraction of a nonlinear differential equations is the region of initial points of solution tending to the equilibrium points of the systems as the time going. Determining the domain of attraction is one of the most important problems to investigate nonlinear dynamical systems. In this article, we first present two algorithms to determine the domain of attraction by using the moment matrices. In addition, as an application we consider a class of SIRS infection model and discuss asymptotical stability by Lyapunov method, and also estimate the domain of attraction by using the algorithms.
ESTIMATING THE DOMAIN OF ATTRACTION OF HIV-1 SYSTEM BASED ON MOMENT METHOD
LI, CHUNJI,YAO, HAN The Korean Society for Computational and Applied M 2018 Journal of applied mathematics & informatics Vol.36 No.5
In this article, we discuss the domain of attraction of HIV-1 system by using the moment theory. First, the asymptotic stabilities of the equilibrium point of the system are given, and then we introduce how to use the moment method to estimate domain of attraction. Finally, one simulation shows the effectiveness of moment method.
Structure Eigenvectors of the Ricci Tensor in a Real Hypersurface of a Complex Projective Space
LI, CHUNJI,KI, U-HANG 대한수학회 2006 Kyungpook mathematical journal Vol.46 No.4
It is known that there are no real hypersurfaces with parallel Ricci tensor in a nonflat complex space form ([6], [9]). In this paper we investigate real hypersurfaces in a complex projective space P_(n)C using some conditions of the Ricci tensor S which are weaker than ▽S = 0. We characterize Hopf hypersurfaces of P_(n)C.
COMPLEX MOMENT MATRICES VIA HALMOS-BRAM AND EMBRY CONDITIONS
Li, Chunji,Jung, Il-Bong,Park, Sang-Soo Korean Mathematical Society 2007 대한수학회지 Vol.44 No.4
By considering a bridge between Bram-Halmos and Embry characterizations for the subnormality of cyclic operators, we extend the Curto-Fialkow and Embry truncated complex moment problem, and solve the problem finding the finitely atomic representing measure ${\mu}$ such that ${\gamma}_{ij}={\int}\bar{z}^iz^jd{\mu},\;(0{\le}i+j{\le}2n,\;|i-j|{\le}n+s,\;0{\le}s{\le}n);$ the cases of s = n and s = 0 are induced by Bram-Halmos and Embry characterizations, respectively. The former is the Curto-Fialkow truncated complex moment problem and the latter is the Embry truncated complex moment problem.
ESTIMATING THE DOMAIN OF ATTRACTION VIA MOMENT MATRICES
Li, Chunji,Ryoo, Cheon-Seoung,Li, Ning,Cao, Lili Korean Mathematical Society 2009 대한수학회보 Vol.46 No.6
The domain of attraction of a nonlinear differential equations is the region of initial points of solution tending to the equilibrium points of the systems as the time going. Determining the domain of attraction is one of the most important problems to investigate nonlinear dynamical systems. In this article, we first present two algorithms to determine the domain of attraction by using the moment matrices. In addition, as an application we consider a class of SIRS infection model and discuss asymptotical stability by Lyapunov method, and also estimate the domain of attraction by using the algorithms.
A note on cubically hyponormal weighted shifts
Chunji Li,Muneo Cho,이미령 대한수학회 2014 대한수학회보 Vol.51 No.4
In this paper, we show that any cubically hyponormal weight- ed shift with first two equal weights is flat. And we give an example of a weighted shift which is not cubically hyponormal but almost-cubically hyponormal.