Speed‑sensorless control of induction motors based on adaptive EKF

Lisi Tian,Zhaoxun Li,Zaixiang Wang,Xiaoxu Sun,Tao Guo,Hao Zhang 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12

The noise covariance matrices Q and R are set as constant values in the traditional extended Kalman filter (TEKF). They are determined by trial and error. This process is very complicated and the optimal matrices are difficult to determine. Inaddition, when the characteristic of noise changes, the matrices cannot be adjusted correspondingly, and the performance of the TEKF deteriorates. Therefore, an adaptive EKF algorithm based on the maximum likelihood estimation criterionwith limited memory exponential weighting (EW-MLE-AEKF) is proposed in this paper. In the proposed EW-MLE-AEKF algorithm, the windowing method is adopted to save the posterior residual sequences in the previous N calculation periods. Then, these sequences are used to estimate and update the process noise covariance matrix Q in real time. To speed up the convergence speed of the estimation, a limited memory exponential weighting algorithm is added to the windowingmethod, which can increase the importance of recent data. Through real-time experiments, the superiority of the proposed EW-MLE-AEKF algorithm is verified.

A Current Dynamic Analysis Based Open-Circuit Fault Diagnosis Method in Voltage-Source Inverter Fed Induction Motors

Lisi Tian,Feng Wu,Yi Shi,Jin Zhao 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

This paper proposed a real-time, low-cost, fast transistor open-circuit fault diagnosis method for voltage-source inverter fed induction motors. A transistor open-circuit changes the symmetry of the inverter topology, leading to different similarities among three phase load currents. In this paper, dynamic time warping is proposed to describe the similarities among load currents. The proposed diagnosis is independent of the system model and needs no extra sensors or electrical circuits. Both simulation and experimental results show the high efficiency of the proposed fault diagnosis method.

A Current Dynamic Analysis Based Open-Circuit Fault Diagnosis Method in Voltage-Source Inverter Fed Induction Motors

Tian, Lisi,Wu, Feng,Shi, Yi,Zhao, Jin The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

This paper proposed a real-time, low-cost, fast transistor open-circuit fault diagnosis method for voltage-source inverter fed induction motors. A transistor open-circuit changes the symmetry of the inverter topology, leading to different similarities among three phase load currents. In this paper, dynamic time warping is proposed to describe the similarities among load currents. The proposed diagnosis is independent of the system model and needs no extra sensors or electrical circuits. Both simulation and experimental results show the high efficiency of the proposed fault diagnosis method.

Entrepreneurship and the Hidden Economy: an Extended Matching Model

Gaetano Lisi,Maurizio Pugno 한국국제경제학회 2010 International Economic Journal Vol.24 No.4

This paper develops a labour market matching model in order to address the problem of the persistence of the hidden sector and of its regional concentration, as in Italy and in the enlarged Europe. The main novel features of the model are that entrepreneurial ability affects job productivity, and that regular firms receive negative externalities from the hidden sector, which may capture the pressure typically exerted by corruption and organised crime, and positive externalities from the other regular firms. At least one interior equilibrium emerges, thus providing an explanation for the so-called 'shadow puzzle', with the possibility that tougher monitoring may reduce both the hidden sector and unemployment. If externalities are non-linear, two equilibria may emerge, thus accounting for regional dualism. The 'better' equilibrium is in fact characterised by a smaller hidden sector, higher levels of overall productivity, output, entrepreneurial ability used, extra-profits, relative wages, and more favourable externalities.

중국 고등학교 교사의 셀프리더십이 직무만족에 미치는 영향에서 대인관계와 교사효능감의 매개효과-허베이성을 중심으로

파려사(Ba Lisi),유평수(Yu Pyeongsu) 한국아시아학회 2021 아시아연구 Vol.24 No.4

본 연구는 중국 고등학교 교사의 셀프리더십이 직무만족에 영향을 미치는 과정에서 대인관계, 교사효능감의 매개효과를 밝히는 데 목적을 두고 있다. 연구목적을 달성하기 위해 중국 동북쪽에 위치한 H성 3개시(A시 200명, B시 250명, C시 100명) 에 근무하는 고등학교 교사 550명을 대상으로 설문조사를 실시하였다. 설문지 배부는 2020년 12월 20일부터 2021년 1월 19일까지 4주간 걸쳐 실시하였으며, 수집된 자료는 SPSS 25.0과 AMOS 25.0 프로그램을 이용하여 분석하였다. 연구결과와 논의를 토대로 결론을 다음과 같이 제시하고자 한다. 첫째, 교사의 셀프리더십은 대인관계와 교사효능감을 통해서 직무만족에 유의하게 직·간접적으로 영향을 미친다. 둘째, 교사의 대인관계는 셀프리더십과 직무만족 관계에서 부분 매개변인으로 정적인 영향을 미치는 것으로 확인되었다. 셋째, 교사효능감은 셀프리더십과 직무만족 관계에서 부분 매개변인으로 정적인 영향을 미치는 것으로 확인되었다. 넷째, 대인관계와 교사효능감은 셀프리더십과 직무만족 관계에서 이중매개변인으로 정적인 영향을 미치는 것으로 확인되었다. 따라서 교사들의 직무만족도를 증진하기 위해서는 자기 동기화와 자기 통제력을 강화할 수 있는 실천적인 전략을 마련하고 자기의 능력을 발휘하면서 자신의 성취, 삶의 질을 높이기 위한 노력을 기울여야 하며, 동료들 간에 서로 도움을 주고 받으며 그들과 협력, 존중, 배려 등의 태도를 지녀야 한다. The purpose of this study is to reveal the mediating effects of interpersonal relationships and teacher efficacy in the process that Chinese high school teachers" self-leadership affects job satisfaction. A survey was conducted with 550 high school teachers working in 3 cities in H province located in northeast China. The distribution of the questionnaire was conducted for 4 weeks from December 20, 2020 to January 19, 2021. The collected data were analyzed using SPSS 25.0 and AMOS 25.0 programs. Based on the research results and discussion, I would like to present the following conclusions. First, it was found that teachers" self-leadership significantly directly or indirectly affected job satisfaction through interpersonal relationships and teacher efficacy. Second, it was confirmed that the interpersonal relationship of teachers had a positive influence as a partial mediating variable in the relationship between self-leadership and job satisfaction. Third, teacher efficacy was found to have a positive effect as a partial mediating variable in the relationship between self-leadership and job satisfaction. Fourth, interpersonal relationship and teacher efficacy were found to have a positive effect as a double mediator in the relationship between self-leadership and job satisfaction.

Neuronal Apoptosis

Shiqi Luo,Lisi OuYang,Jie Wei,Feng Wu,Zhongdao Wu,Wanlong Lei,Dongjuan Yuan 대한기생충학열대의학회 2017 The Korean Journal of Parasitology Vol.55 No.3

Dynamic analysis of bridge girders submitted to an eccentric moving load

Ricardo F. Vieira,Diego Lisi,Francisco B. Virtuoso 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.1

The cross-section warping due to the passage of high-speed trains can be a relevant issue to consider in the dynamic analysis of bridges due to (i) the usual layout of railway systems, resulting in eccentric moving loads; and (ii) the use of cross-sections prone to warping deformations. A thin-walled beam formulation for the dynamic analysis of bridges including the cross section warping is presented in this paper. Towards a numerical implementation of the beam formulation, a finite element with seven degrees of freedom is proposed. In order to easily consider the compatibility between elements, and since the coupling between flexural and torsional effects occurs in non-symmetric cross-sections due to dynamic effects, a single axis is considered for the element. The coupled flexural-torsional free vibration of thin-walled beams is analysed through the presented beam model, comparing the results with analytical solutions presented in the literature. The dynamic analysis due to an eccentric moving load, which results in a coupled flexuraltorsional vibration, is considered in the literature by analytical solutions, being therefore of a limited applicability in practice engineering. In this paper, the dynamic response due to an eccentric moving load is obtained from the proposed finite element beam model that includes warping by a modal analysis.

Dynamic analysis of bridge girders submitted to an eccentric moving load

Vieira, Ricardo F.,Lisi, Diego,Virtuoso, Francisco B. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.52 No.1

The cross-section warping due to the passage of high-speed trains can be a relevant issue to consider in the dynamic analysis of bridges due to (i) the usual layout of railway systems, resulting in eccentric moving loads; and (ii) the use of cross-sections prone to warping deformations. A thin-walled beam formulation for the dynamic analysis of bridges including the cross section warping is presented in this paper. Towards a numerical implementation of the beam formulation, a finite element with seven degrees of freedom is proposed. In order to easily consider the compatibility between elements, and since the coupling between flexural and torsional effects occurs in non-symmetric cross-sections due to dynamic effects, a single axis is considered for the element. The coupled flexural-torsional free vibration of thin-walled beams is analysed through the presented beam model, comparing the results with analytical solutions presented in the literature. The dynamic analysis due to an eccentric moving load, which results in a coupled flexural-torsional vibration, is considered in the literature by analytical solutions, being therefore of a limited applicability in practice engineering. In this paper, the dynamic response due to an eccentric moving load is obtained from the proposed finite element beam model that includes warping by a modal analysis.

Highly stable core–shell Pt-CeO2 nanoparticles electrochemically deposited onto Fecralloy foam reactors for the catalytic oxidation of CO

S. Cimino,L. Lisi,G. Totarella,S. Barison,M. Musiani,E. Verlato 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

The sequential electrodeposition of Pt nanoparticles and CeO2 protective layers has been explored as a simple method to prepare structured catalytic reactors characterized by a core–shell metal-metal oxide active phase directly anchored onto metallic (Fecralloy) 3D open foam substrates. The application of a CeO2 overlayer onto preformed Pt nanoparticles promoted the intrinsic catalytic activity for CO oxidation and induced a remarkable stabilization effect against sintering and extensive reconstruction of the active phase up to 800 °C.

Torque Ripple Suppression for Permanent-Magnet Synchronous Motor based on Enhanced LADRC Strategy

Zhang Zhaoyuan,Chen Yao,Tan Lisi,Zhao Chaohui 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

Permanent-Magnet Synchronous Motor has shown advanced performance in the industry, but its smooth operation is aff ected by torque ripple. The conventional Linear Active Disturbance Rejection Controller (LADRC) has a strong anti-interference ability. However, this usually makes it more sensitive to measurement noise, reducing steady-state accuracy. This study proposes an Enhanced LADRC controller to obtain strong system disturbance and noise suppression performance. Firstly, the total disturbance diff erential signal is introduced into the Linear Extended State Observer to improve the anti-disturbance ability of the system, and the bandwidth parameter confi guration method is used to reduce the number of parameters be adjusted in the controller to two. Second, A Fal-Filter is built through the nonlinear function and inserted into the controller to weaken the measurement noise. Finally, the simulation model is established on the dSPACE motor control platform, and the corresponding control algorithm is implemented. Simulation and experimental results show that the control scheme can signifi cantly improve the phase current distortion and reduce torque ripple.