• Title/Summary/Keyword: State-space vector

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Modified Direct Torque Control using Algorithm Control of Stator Flux Estimation and Space Vector Modulation Based on Fuzzy Logic Control for Achieving High Performance from Induction Motors

  • Rashag, Hassan Farhan;Koh, S.P.;Abdalla, Ahmed N.;Tan, Nadia M.L.;Chong, K.H.
    • Journal of Power Electronics
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    • v.13 no.3
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    • pp.369-380
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    • 2013
  • Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

Verb Prediction for Korean Language Disorders in Augmentative Communicator using the Neural Network (신경망을 이용한 언어장애인용 문장발생장치의 동사예측)

  • Lee Eunsil;Min Hongki;Hong Seunghong
    • Journal of the Institute of Convergence Signal Processing
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    • v.1 no.1
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    • pp.32-41
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    • 2000
  • In this paper, we proposed a method which predict the verb by using the neural network in order to enhance communication rate in augmentative communication system for Korean language disorders. Each word is represented by an information vector according to syntax and semantics, and is positioned at the state space by being partitioned into various regions different from a dictionary-like lexicon. Conceptual similarity is realized through position in state space. When a symbol was pressed, we could find the word for the symbol at the position in the state space. In order to prevent verb prediction's redundancy according to input units, we predicted the verb after separating class using the neural network. In the result we can enhance $20\% communication rate in the restricted space

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Interactive Facial Expression Animation of Motion Data using CCA (CCA 투영기법을 사용한 모션 데이터의 대화식 얼굴 표정 애니메이션)

  • Kim Sung-Ho
    • Journal of Internet Computing and Services
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    • v.6 no.1
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    • pp.85-93
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    • 2005
  • This paper describes how to distribute high multi-dimensional facial expression data of vast quantity over a suitable space and produce facial expression animations by selecting expressions while animator navigates this space in real-time. We have constructed facial spaces by using about 2400 facial expression frames on this paper. These facial spaces are created by calculating of the shortest distance between two random expressions. The distance between two points In the space of expression, which is manifold space, is described approximately as following; When the linear distance of them is shorter than a decided value, if the two expressions are adjacent after defining the expression state vector of facial status using distance matrix expressing distance between two markers, this will be considered as the shortest distance (manifold distance) of the two expressions. Once the distance of those adjacent expressions was decided, We have taken a Floyd algorithm connecting these adjacent distances to yield the shortest distance of the two expressions. We have used CCA(Curvilinear Component Analysis) technique to visualize multi-dimensional spaces, the form of expressing space, into two dimensions. While the animators navigate this two dimensional spaces, they produce a facial animation by using user interface in real-time.

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The facial expression generation of vector graphic character using the simplified principle component vector (간소화된 주성분 벡터를 이용한 벡터 그래픽 캐릭터의 얼굴표정 생성)

  • Park, Tae-Hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.9
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    • pp.1547-1553
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    • 2008
  • This paper presents a method that generates various facial expressions of vector graphic character by using the simplified principle component vector. First, we analyze principle components to the nine facial expression(astonished, delighted, etc.) redefined based on Russell's internal emotion state. From this, we find principle component vector having the biggest effect on the character's facial feature and expression and generate the facial expression by using that. Also we create natural intermediate characters and expressions by interpolating weighting values to character's feature and expression. We can save memory space considerably, and create intermediate expressions with a small computation. Hence the performance of character generation system can be considerably improved in web, mobile service and game that real time control is required.

An Active Auxiliary Quasi-Resonant Commutation Block Snubber-Assisted Three Phase Voltage Source Soft Switching PFC Rectifier using IGBTs

  • Hiraki Eiji;Nakaoka Mutsuo;Sugimoto Shigeyuki;Ogawa Shigeaki
    • Journal of Power Electronics
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    • v.5 no.1
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    • pp.29-35
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    • 2005
  • This paper presents a novel prototype of an active auxiliary quasi-resonant snubber(Auxiliary Quasi-Resonant Commutation Block-Link; ARCB)-assisted three phase voltage source soft switching space voltage vector modulated PFC rectifier, which uses Zero Voltage Soft Switching (ZVS) commutation. The operating principles of this digitally-controlled three phase soft switching PWM-PFC rectifier system with an instantaneous power feedback scheme are illustrated and its steady-state performance is evaluated using computer-aided simulation analysis.

New Guidance Filter Structure for Homing Missiles with Strapdown IIR Seeker

  • Kim, Tae-Hun;Kim, Jong-Han;Kim, Philsung
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.4
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    • pp.757-766
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    • 2017
  • For implementing the proportional navigation guidance law on passive homing missiles equipped with strapdown imaging infrared seekers, the line-of-sight angles and rates with respect to the inertial frame should be estimated by carefully handling the parasitic instability effect due to the seeker's latency. By introducing a new state vector representation along with the Pade approximation for compensating the time-delay of the seeker, this paper proposes a new guidance filter structure, stochastic dynamic models and measurement equations, in three-dimensional homing problem. Then, it derives the line-of-sight angle and rate estimator in general two-dimensional engagement by applying the extended Kalman filter to the proposed structure. The estimation performance and the characteristics of the proposed filter were evaluated via a series of numerical experiments.

An Overmodulation Strategy for SVPWM Inverter (SVPWM인버터의 과변조 기법)

  • Kim, Sang-Hoon;Choi, Yun-Young
    • Journal of Industrial Technology
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    • v.20 no.B
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    • pp.147-154
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    • 2000
  • This paper proposes an overmodulation strategy for space-vector PWM(SVPWM). The overmodulation strategy increases a fundamental output voltage and improves a voltage utilization up to the maximum in the overmodulation region. To maintain a linearity of the relation between a reference voltage and a fundamental output voltage, this paper suggests a compensation voltage, whose magnitude or phase is modified to the proposed control scheme. The practical implementation is simple and it is applied to improve an output voltage of SVPWM controlled AC Motor in the steady-state. The characteristic of the proposed strategy is confirmed by simulations and experiments for a V/F control of a induction motor.

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Analysis for dc Boost Control System Using Z-Source Inverter

  • Tran, Quang-Vinh;Chun, Tae-Won;Lee, Hong-Hee;Ahn, Jung-Ryol
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.647-650
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    • 2005
  • The paper aims on an analysis for dc boost control using Z-source inverter. The modified space vector PWM method is used for controlling both the dc boost and ac output controls in the Z-source inverter. The capacitor voltage and the voltage stress of device with both the shoot-through time and modulation index are analyzed considering the zero state time of inverter. The theoretical analysis is verified with the simulation studies and experiments with 32-bit DSP.

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7-Phase PMSM Motor Drive System Using Space Voltage Vector PWM (공기전압벡터 PWM을 이용한 7상 영구자석형 동기전동기의 구동 시스템)

  • Kim, H.G.;Choi, M.G.;Jeong, B.H.;Mok, H.S.;Choe, G.H.
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.42-44
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    • 2005
  • The motor research of pre-existing attaches importance about one and three motor of reduce torque ripple and speed control. 3-Phase PMSM Motor, which is generally used, has limited usage in high speed, due to pulsation torque and variable speed. To solve this problem it is necessary to increase invariable, pole number or the number of slots. In this paper 7-Phase PMSM Motor of Steady state analysis of Torque and Output Voltage characteristic.7-Phase modulation method with Space Voltage Vector is studied for ideal operation of controller.

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A New Method for Coronal Force-Free Field Computation That Exactly Implements the Boundary Normal Current Density Condition

  • Yi, Sibaek;Jun, Hongdal;Lee, Junggi;Choe, G.S.
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.2
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    • pp.71.3-71.3
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    • 2019
  • Previously we developed a method of coronal force-free field construction using vector potentials. In this method, the boundary normal component of the vector potential should be adjusted at every iteration step to implement the boundary normal current density, which is provided by observations. The method was a variational method in the sense that the excessive kinetic energy is removed from the system at every iteration step. The boundary condition imposing the normal current density, however, is not compatible with the variational procedure seeking for the minimum energy state, which is employed by most force-free field solvers currently being used. To resolve this problem, we have developed a totally new method of force-free field construction. Our new method uses a unique magnetic field description using two scalar functions. Our procedure is non-variational and can impose the boundary normal current density exactly. We have tested the new force-free solver for standard Low & Lou fields and Titov-Demoulin flux ropes. Our code excels others in both examples, especially in Titov-Demoulin flux ropes, for which most codes available now yield poor results. Application to a real active region will also be presented.

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