• Title/Summary/Keyword: Soft output

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Design of Low-Density Parity-Check Codes for Multi-Input Multi-Output Systems (Multi-Input Multi-Output System을 위한 Low-Density Parity-Check codes 설계)

  • Shin, Jeong-Hwan;Heo, Jun
    • Proceedings of the IEEK Conference
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    • 2008.06a
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    • pp.161-162
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    • 2008
  • In this paper we design an irregular low-density parity-check (LDPC) code for a multi-input multi-output (MIMO) system. The considered MIMO system is minimum mean square error soft-interference cancellation (MMSE-SIC) detector. The MMSE-SIC detector and the LDPC decoder exchange soft information and consist a turbo iterative detection and decoding receiver. Extrinsic information transfer (EXIT) charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the input-output transfer chart of the MMSE-SIC detector. It is shown that the performance of the designed LDPC code is much better than that of conventional LDPC code optimized for the AWGN channel.

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Analysis and Implementation of a DC-DC Converter with an Active Snubber

  • Lin, Bor-Ren;Lin, Li-An
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.779-786
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    • 2011
  • This paper presents a soft switching converter to achieve the functions of zero voltage switching (ZVS) turn-on for the power switches and dc voltage step-up. Two circuit modules are connected in parallel in order to achieve load current sharing and to reduce the size of the transformer core. An active snubber is connected between two transformers in order to absorb the energy stored in the leakage and magnetizing inductances and to limit the voltage stresses across the switches. During the commutation stage of the two complementary switches, the output capacitance of the two switches and the leakage inductance of the transformers are resonant. Thus, the power switches can be turned on under ZVS. No output filter inductor is used in the proposed converter and the voltage stresses of the output diodes is clamped to the output voltage. The circuit configuration, the operation principles and the design considerations are presented. Finally, laboratory experiments with a 340W prototype, verifying the effectiveness of the proposed converter, are described.

Soft-Switching Auxiliary Current Control for Improving Load Transient Response of Buck Converter

  • Kim, Doogwook;Shin, Joonho;Shin, Jong-Won
    • Proceedings of the KIPE Conference
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    • 2020.08a
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    • pp.160-162
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    • 2020
  • A control technique for the auxiliary buck/boost converter is proposed herein to improve the load transient response of the buck converter. The proposed technique improves the system efficiency by enabling the soft switching operation of the auxiliary converter. The design guidelines for achieving capacitor charge balance for the output capacitor during the transient are also presented herein. The experimental results revealed that the output voltage undershoot and settling time during the load step-up transient were 40 mV and 14 ㎲, respectively, and the output voltage overshoot and settling time during the load step-down transient were 35 mV and 21 ㎲, respectively. The performance and effectiveness of the proposed technique were experimentally verified using a prototype buck converter with a 15-V input, 3.3-V output, and 200-kHz switching frequency.

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A Secondary Resonance Soft Switching Half Bridge DC-DC Converter with an Inductive Output Filter

  • Chen, Zhang-yong;Chen, Yong
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1391-1401
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    • 2017
  • In this paper, a secondary resonance half-bridge dc-dc converter with an inductive output filter is presented. The primary side of such a converter utilizes asymmetric pulse width modulation (APWM) to achieve zero-voltage switching (ZVS) of the switches, and clamps the voltage of the switch to the input voltage. In addition, zero current switching (ZCS) of the output diode is achieved by a half-wave rectifier circuit with a filter inductor and a resonant branch in the secondary side of the proposed converter. Thus, the switching losses and diode reverse-recovery losses are eliminated, and the performance of the converter can be improved. Furthermore, an inductive output filter exists in the converter reduce the output current ripple. The operational principle, performance analysis and design equation of this converter are given in this paper. The analysis results show that the output diode voltage stress is independent of the duty cycle, and that the voltage gain is almost linear, similar to that of the isolation Buck-type converter. Finally, a 200V~380V input, 24V/2A output experimental prototype is built to verify the theoretical analysis.

A Study on Soft Switching PWM Boost Converter using ZVT Technique (ZVT 기술을 이용한 soft switching DC-DC Boost 컨버터에 관한 연구)

  • 김춘삼
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.141-144
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    • 2000
  • Recently DC-DC converters significantly increase the total losses as rising switching frequency. Traditional soft switching technique for reducing switching losses even increase voltage/current stress of switch. In this paper Resonant circuit for soft switching is connected in parallel with power stage and only operates just before turn-on of the main operates just before turn-on of the main switch, Therefore This doesn't affect the total circuit operation. ZNT-PWM converter designed with 170-260V input 4--V 5A output and 100kHz switching frequency is tested respectively with 500W. 1kW, 1.5kW, and 2kW loads.

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High Efficiency Design Procedure of a Second Stage Phase Shifted Full Bridge Converter for Battery Charge Applications Based on Wide Output Voltage and Load Ranges

  • Cetin, Sevilay
    • Journal of Power Electronics
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    • v.18 no.4
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    • pp.975-984
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    • 2018
  • This work presents a high efficiency phase shifted full bridge (PSFB) DC-DC converter for use in the second stage of a battery charger for neighborhood electrical vehicle (EV) applications. In the design of the converter, Lithium-ion battery cells are preferred due to their high voltage and current rates, which provide a high power density. This requires wide range output voltage regulation for PSFB converter operation. In addition, the battery charger works with a light load when the battery charge voltage reaches its maximum value. The soft switching of the PSFB converter depends on the dead time optimization and load condition. As a result, the converter has to work with soft switching at a wide range output voltage and under light conditions to reach high efficiency. The operation principles of the PSFB converter for the continuous current mode (CCM) and the discontinuous current mode (DCM) are defined. The performance of the PSFB converter is analyzed in detail based on wide range output voltage and load conditions in terms of high efficiency. In order to validate performance analysis, a prototype is built with 42-54 V / 15 A output values at a 200 kHz switching frequency. The measured maximum efficiency values are obtained as 94.4% and 76.6% at full and at 2% load conditions, respectively.

Soft Switching High Power Factor Buck Converter (Soft Switching방식 고역률 강압형 컨버터)

  • 구헌회;조기연
    • Proceedings of the KIPE Conference
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    • 1997.07a
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    • pp.243-246
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    • 1997
  • In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, a input capacitor can be small enough to filter input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn of of the switching device is a zero current switching(ZCS) and high power factor input is obtained. In addition, zero voltage switching(ZVS) at turn of is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontious conduction mode operation.

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Analysis of Hybrid Converter with Wide Voltage Range Operation

  • Lin, Bor-Ren
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1099-1107
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    • 2019
  • A soft switching converter with wide voltage range operation is investigated in this paper. A series resonant converter is implemented to achieve a high circuit efficiency with soft switching characteristics on power switches and rectifier diodes. To improve the weakness of the narrow voltage range in LLC converters, an alternating current (ac) power switch is used on the primary side to select a half-bridge or full-bridge resonant circuit to implement 4:1 voltage range operation. On the secondary-side, another ac power switch is adopted to select a full-wave rectifier or voltage-doubler rectifier to achiever an additional 2:1 output voltage range. Therefore, the proposed resonant converter has the capacity for 8:1 (320V~40V) wide output voltage operation. A single-stage hybrid resonant converter is employed in the study circuit instead of a two-stage dc converter to achiever wide voltage range operation. As a result, the study converter has better converter efficiency. The theoretical analysis and circuit characteristics are verified by experiments with a prototype circuit.

Energy efficient joint iterative SIC-MMSE MIMO detection (에너지 효율적 반복 SIC-MMSE MIMO 검출)

  • Ngayahala, F.C. Kamaha;Ahmed, Saleem;Kim, Sooyoung
    • Journal of Satellite, Information and Communications
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    • v.10 no.1
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    • pp.22-28
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    • 2015
  • In this paper, we propose a new computationally efficient joint iterative multi-input multi-output (MIMO) detection scheme using a soft interference cancellation and minimum mean squared-error (SIC-MMSE) method. The critical computational burden of the SIC-MMSE scheme lies in the multiple inverse operations of the complex matrices. We find a new way which requires only a single matrix inversion by utilizing the Taylor series expansion of the matrix, and thus the computational complexity can be reduced. The computational complexity reduction increases as the number of antennas is increased. The simulation results show that our method produces almost the same performances as the conventional SIC-MMSE with reduced computational complexity.

A Novel Boost DC-DC Converter using High Frequency Coupled Inductor Series Resonant ZCS-PFM Chopper Control Method (고주파 결합 인덕터 직렬 공진형 ZCS-PFM 초퍼 제어 방식을 이용한 새로운 승압형 DC-DC 컨버터)

  • Kim, Hong-Shin;Heo, Young-Hwan;Mun, Sang-Pil;Park, Han-Seok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.66 no.2
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    • pp.63-68
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    • 2017
  • This paper proposes a new non-isolated DC conversion circuit topology of the voltage source coupled inductor series resonant high-frequency PFM controlled boost chopper type DC-DC power converter using two in one IGBT power module, which can efficiently operate under a principle of zero current soft switching for wide output regulation voltage setting ranges and wide fluctuation of the input DC side voltage as well as the load variation ranges. Its steady state operating principle and the output voltage regulation characteristics in the open-loop-based output voltage control scheme without PI controller loop are described and evaluated from theoretical and experimented viewpoints. Finally, in this paper the computer-aided simulation steady-state analysis and the experimental results are presented in order to prove the effectiveness and the validity of voltage regulation characteristics of the proposed series resonant zero current soft switching boost chopper type DC-DC power converter circuit using IGBTs which is based on simple pulse frequency modulation strategy more than, 20kHz.