• Title/Summary/Keyword: Hybrid switching method

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Hybrid Switching Method of Three-level DC-DC converter for EV Fast Charger with Wide Charging Voltage Range (넓은 충전 전압범위를 갖는 전기자동차용 급속충전기를 위한 3레벨 DC-DC 컨버터의 하이브리드 스위칭 기법)

  • Jeong, Heon soo;Park, Jun Sung;Choi, Sewan
    • Proceedings of the KIPE Conference
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    • 2013.11a
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    • pp.15-16
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    • 2013
  • 전기자동차용 급속 충전기에서 전력변환 효율은 절연형 DC-DC 컨버터에 의해 좌우된다. 이때 DC-DC 컨버터의 출력 전압 범위가 넓기 때문에 기존의 3레벨 컨버터를 사용할 경우 충전전압이 낮을 때 순환전류가 커지는 문제점이 있다. 본 논문에서는 넓은 충전전압범위를 갖는 전기자동차용 급속충전기를 위한 3레벨 DC-DC 컨버터의 하이브리드 스위칭 기법을 제안한다. 제안한 하이브리드 스위칭 기법은 충전전압이 낮을 때 순환전류를 줄일 수 있어 주로 낮은 배터리 전압에서 동작하는 CC충전 모드 시 도통 손실을 줄일 수 있다. 또한 커플인덕터를 사용하여 순환전류를 줄이고 Lagging Lag 스위치의 ZCS 턴오프를 성취시켜 손실을 줄일 수 있다. 기존의 스위칭 방법과 하이브리드 스위칭 기법에 따른 손실을 비교하여 제안한 스위칭 기법의 타당성을 검증하였다.

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Discriminative Training of Stochastic Segment Model Based on HMM Segmentation for Continuous Speech Recognition

  • Chung, Yong-Joo;Un, Chong-Kwan
    • The Journal of the Acoustical Society of Korea
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    • v.15 no.4E
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    • pp.21-27
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    • 1996
  • In this paper, we propose a discriminative training algorithm for the stochastic segment model (SSM) in continuous speech recognition. As the SSM is usually trained by maximum likelihood estimation (MLE), a discriminative training algorithm is required to improve the recognition performance. Since the SSM does not assume the conditional independence of observation sequence as is done in hidden Markov models (HMMs), the search space for decoding an unknown input utterance is increased considerably. To reduce the computational complexity and starch space amount in an iterative training algorithm for discriminative SSMs, a hybrid architecture of SSMs and HMMs is programming using HMMs. Given the segment boundaries, the parameters of the SSM are discriminatively trained by the minimum error classification criterion based on a generalized probabilistic descent (GPD) method. With the discriminative training of the SSM, the word error rate is reduced by 17% compared with the MLE-trained SSM in speaker-independent continuous speech recognition.

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Fuzzy Variable Structure Control System for Fuel Injected Automotive Engines (연료분사식 자동차엔진의 퍼지가변구조 제어시스템)

  • Nam, Sae-Kyu;Yoo, Wan-Suk
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7 s.94
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    • pp.1813-1822
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    • 1993
  • An algorithm of fuzzy variable structrue control is proposed to design a closed loop fuel-injection system for the emission control of automotive gasoline engines. Fuzzy control is combined with sliding control at the switching boundary layer to improve the chattering of the stoichiometric air to fuel ratio. Multi-staged fuzzy rules are introduced to improve the adaptiveness of control system for the various operating conditions of engines, and a simplified technique of fuzzy inference is also adopted to improve the computational efficiency based on nonfuzzy micro-processors. The proposed method provides an effective way of engine controller design due to its hybrid structure satisfying the requirements of robustness and stability. The great potential of the fuzzy variable structure control is shown through a hardware-testing with an Intel 80C186 processor for controller and a typical engine-only model on an AD-100 computer.

Modeling and Regulator Design for Three-Input Power Systems with Decoupling Control

  • Li, Yan;Zheng, Trillion Q.;Zhao, Chuang;Chen, Jiayao
    • Journal of Power Electronics
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    • v.12 no.6
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    • pp.912-924
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    • 2012
  • In hybrid renewable power systems, the use of a multiple-input dc/dc converter (MIC) leads to simpler circuit and lower cost, when compared to the conventional use of several single-input converters. This paper proposed a novel three-input buck/boost/buck-boost converter, which can be used in applications with various values of input voltage. The energy sources in this converter can deliver power to the load either simultaneously or individually in one switching period. The steady relationship, the power management strategy and the small-signal circuit model of this converter have been derived. With decoupling technology, modeling and regulator design can be obtained under multi-loop control modes. Finally, three generating methods of a multiple-input buck/boost/buck-boost converter is given, and this method can be extended to the other multiple-input dc/dc converters.

Torque Ripple Reduction and Switching Loss Reduction Method for Induction Motors by Hybrid PWM (전압변조기법 변경을 이용한 유도전동기의 스위칭 손실 및 토크 리플 저감 방법)

  • Lee, Sung Ho;Kim, Sol Joon;Lee, June-Seok;Lee, Chang-Moo
    • Proceedings of the KIPE Conference
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    • 2018.11a
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    • pp.189-190
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    • 2018
  • 본 논문에서는 유도전동기의 토크 리플 및 스위칭 손실 저감을 위해 전압변조기법인 공간벡터변조(Space Vector Pulse Width Modulation, SVPWM) 기법과 불연속전압변조(Discontinuous Pulse Width Modulation, DPWM) 기법을 혼합하여 사용하는 새로운 변조기법을 제안한다. 제안하는 방식은 지령전압이 최대인 부근에서 SVPWM 기법을 사용하며, 나머지 구간에서는 DPWM 기법을 적용한다. 전 구간 단일기법을 적용할 때와 비교하여 제안하는 방식은 토크 리플 및 스위칭 손실을 효율적으로 저감시킬 수 있으며 시뮬레이션을 통해 타당성을 검증한다.

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Staggered and Inverted Staggered Type Organic-Inorganic Hybrid TFTs with ZnO Channel Layer Deposited by Atomic Layer Deposition

  • Gong, Su-Cheol;Ryu, Sang-Ouk;Bang, Seok-Hwan;Jung, Woo-Ho;Jeon, Hyeong-Tag;Kim, Hyun-Chul;Choi, Young-Jun;Park, Hyung-Ho;Chang, Ho-Jung
    • Journal of the Microelectronics and Packaging Society
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    • v.16 no.4
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    • pp.17-22
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    • 2009
  • Two different organic-inorganic hybrid thin film transistors (OITFTs) with the structures of glass/ITO/ZnO/PMMA/Al (staggered structure) and glass/ITO/PMMA/ZnO/Al (inverted staggered structure), were fabricated and their electrical and structural properties were compared. The ZnO thin films used as active channel layers were deposited by the atomic layer deposition (ALD) method at a temperature of $100^{\circ}C$. To investigate the effect of the substrates on their properties, the ZnO films were deposited on bare glass, PMMA/glass and ITO/glass substrates and their crystal properties and surface morphologies were analyzed. The structural properties of the ZnO films varied with the substrate conditions. The ZnO film deposited on the ITO/glass substrate showed better crystallinity and morphologies, such as a higher preferred c-axis orientation, lower FWHM value and larger particle size compared with the one deposited on the PMMA/glass substrate. The field effect mobility ($\mu$), threshold voltage ($V_T$) and $I_{on/off}$ switching ratio for the OITFT with the staggered structure were about $0.61\;cm^2/V{\cdot}s$, 5.5 V and $10^2$, whereas those of the OITFT with the inverted staggered structure were found to be $0.31\;cm^2/V{\cdot}s$, 6.8 V and 10, respectively. The improved electrical properties for the staggered OITFTs may originate from the improved crystal properties and larger particle size of the ZnO active layer.

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A Hybrid Error Generation Algorithm Using Confidence Intervals on Signal Constellation (신호 성상도 상의 신뢰구간을 활용한 하이브리드 오차 발생 알고리즘)

  • Oh, Kil Nam
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.11
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    • pp.19-25
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    • 2014
  • For effective updating a blind equalizer, we propose the adaptive algorithm having faster convergence speed required for initial equalization and satisfying low error level required in steady-state while having a gradual and reversible switching characteristics between initial stage and steady-state. The proposed method presents three criteria to distinguish the state of equalized signal, according to the criteria, differently updates the equalizer by using the hybrid error generation algorithm generating one of the three errors. Wherein as the criteria to determine the state of the equalized signal the confidence intervals on the signal constellation are used, an error is generated alternatively according to the confidence interval where equalizer output lies, and the equalizer is updated by, we got convergence quickly and to lower error level. In order to verify the usefulness of the proposed idea, simulation results were compared to the performance of conventional methods.

Effect of Tooth Shape and Unbalanced M.M.F on Static Thrust Force Characteristics of Linear Pulse Motor (리니어 펄스 모터에서 치 형상과 기자력 불평형이 정추력 특성에 미치는 영향)

  • Lee, Dong-Ju;Lee, Eun-Ung;Kim, Seong-Heon;Kim, Seong-Jong
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.3
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    • pp.131-137
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    • 2000
  • 2 phase 8 pole HB-type(flat-type) Linear Pulse Motor can be used as the high precision position actuator because of its many advantages (simple control circuit, high stiffness characteristics, etc). Also, using the microstep drive, its noise and vibration can be reduced considerably and positional resolution may be increased further. But, $20^{\circ}$tapered tooth shape to reduce the normal force have an much effect on the static thrust force characteristics. And, because of hybrid-type LPM, interaction between the permanent magnet and the excitation current have an effect on the various characteristics of LPM. Hence, in this paper, the effect of tooth shape on static thrust force characteristics was analyzed using the air gap permeance by finite element method. For analyzing the effect of unbalance between the m.m.f of permanent magnet and the m.m.f of excitation current, unbalanced m.m.f coefficient $\sigma$ were introduced with the permenace matrix and switching matrix.

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Internet Multicast Routing Protocol Model using MPLS Networks (MPLS망을 이용한 인터넷 멀티캐스트 라우팅 프로토콜 모델)

  • Kim, Young-Jun
    • The KIPS Transactions:PartC
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    • v.10C no.1
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    • pp.77-86
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    • 2003
  • This paper describes the new method for Internet multicast routing protocols using MPLS (Multiprotocol Label Switching) networks. Internet multicast routing protocols are divided into three categories in terms if tree types and tree characteristics : a shortest path tree a shared tree and hybrid tree types. MPLS should support various multicast mechanisms because of extremely different IP multicast architectures, such as uni-/bi-directional link, Flooding/prune tree maintenance mechanism. the existence of different tree types with the same group, etc. There are so many problems over MPLS multicast that the solutions can't be easily figured out. In this Paper, we make a few assumptions on which the solutions of IP multicast routing protocols over MPLS networks are given. A broadcasting label is defined for the shortest path tree types. Cell interleaving problems of the shared tree types is solved by using block-based transmission mechanism. Finally, the existing hybrid-type multicast routing protocol is reasonably modified Shortest Path tree type to support MPLS multicast. It has been shown that these modifications give better performance (transmission delay) than the orignal method.

Efficiency Improvement of Synchronous Boost Converter with Dead Time Control for Fuel Cell-Battery Hybrid System

  • Kim, Do-Yun;Won, Il-Kuen;Lee, Jung-Hyo;Won, Chung-Yuen
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.1891-1901
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    • 2017
  • In this paper, optimal control of the fuel cell and design of a high-efficiency power converter is implemented to build a high-priced fuel cell system with minimum capacity. Conventional power converter devices use a non-isolated boost converter for high efficiency while the battery is charged, and reduce its conduction loss by using MOSFETs instead of diodes. However, the efficiency of the boost converter decreases, since overshoot occurs because there is a moment when the body diode of the MOSFET is conducted during the dead time and huge loss occurs when the dead time for the maximum-power-flowing state is used in the low-power-flowing state. The method proposed in this paper is to adjust the dead time of boost and rectifier switches by predicting the power flow to meet the maximum efficiency in every load condition. After analyzing parasite components, the stability and efficiency of the high-efficiency boost converter is improved by predictive compensation of the delay component of each part, and it is proven by simulation and experience. The variation in switching delay times of each switch of the full-bridge converter is compensated by falling time compensation, a control method of PWM, and it is also proven by simulation and experience.