• Title/Summary/Keyword: discontinuous PWM (DPWM)

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Design of LCL-filter for Grid-Connected Three-Phase Inverters Using a Discontinuous PWM Method (DPWM 방식을 적용한 3상 계통 연계 인버터의 LCL-필터 설계)

  • Lee, Jung-Rok;Seo, Seung Gyu;Lee, Kyo-Beum
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.3
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    • pp.419-427
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    • 2016
  • This paper proposes a design method of LCL-filter for a grid-connected three-phase inverter using a discontinuous PWM (DPWM) method. When using a DPWM method, many harmonic voltages are generated in the inverter output compared to a continuous PWM (CPWM) method. Therefore, an optimized grid-connected filter design is required for a DPWM method. The proposed design method provides generalized formula to design accurate LCL-filter without trial and error procedures. An inverter side inductance is designed by analyzing the current ripple injected to the grid. The Optimized parameters of LCL-filter can be designed by analyzing the total harmonic distortion (THD) and the ripple attenuation factor of the output current. The proposed LCL filter design method is demonstrated by simulation and experimental results.

Discontinuous PWM Scheme for Switching Losses Reduction in Modular Multilevel Converters

  • Jeong, Min-Gyo;Kim, Seok-Min;Lee, June-Seok;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1490-1499
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    • 2017
  • The modular multilevel converter (MMC) is generally considered to be a promising topology for medium-voltage and high-voltage applications. However, in order to apply it to high-power applications, a huge number of switching devices is essential. The numerous switching devices lead to considerable switching losses, high cost and a larger heat sink for each of the switching device. In order to reduce the switching losses of a MMC, this paper analyzes the performance of the conventional discontinuous pulse-width modulation (DPWM) method and its efficiency. In addition, it proposes a modified novel DPWM method for advanced switching losses reduction. The novel DPWM scheme includes an additional rotation method for voltage-balancing and power distribution among sub modules (SMs). Simulation and experimental results verify the effectiveness and performance of the proposed modulation method in terms of its switching losses reduction capability.

The Novel Carrier-Based DPWM Method for 3-level Inverter (3-level inverter를 위한 새로운 Carrier-Based DPWM 기법)

  • 강대욱
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.347-350
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    • 2000
  • This paper deals with the novel DPWM(discontinuous PWM) for 3-level inverter. Although DPWM methods generate higher harmonics than SVPWM they are of special interest because of their lower switching losses. And in the high modulation region the harmonic characteristics of DPWM is superior to the that of CPWM. However when DPWM applies to the 3-level inverter there is the problem that the output state is varied suddenly in the low modulation region($\textrm{m}_{I}$=0~0.5) The novel DPWM that this problem improves will be introduced.

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Single Phase PWM Converter For High-Speed Railway Propulsion System Using Discontinuous PWM (불연속 변조 기법을 이용한 고속철도 추진제어장치용 단상 PWM 컨버터)

  • Song, Min-Sup
    • Journal of the Korean Society for Railway
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    • v.20 no.4
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    • pp.448-457
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    • 2017
  • In this paper, for high speed railway propulsion systems, a single phase PWM Converter using discontinuous PWM (DPWM) was investigated. The conventional PWM Converter uses a low frequency modulation index of less than 10 to reduce switching losses due to high power characteristics, which results in low control frequency bandwidth and requires an additional compensation method. To solve these problems, the DPWM method, which is commonly used in three phase PWM Inverters, was adopted to a single phase PWM Converter. The proposed method was easily implemented using offset voltage techniques. Method can improve the control performance by doubling the frequency modulation index for the same switching loss, and can also bring the same dynamic characteristics among switches. Proposed DPWM method was verified by simulation of 100 kW PWM converter.

A Simple Control Strategy for Balancing the DC-link Voltage of Neutral-Point-Clamped Inverter at Low Modulation Index

  • C.S. Ma;Kim, T.J.;D.W. Kang;D.S. Hyun
    • Journal of Power Electronics
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    • v.3 no.4
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    • pp.205-214
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    • 2003
  • This paper proposes a simple control strategy based on the discontinuous PWM (DPWM) to balance the DC-link voltage of three-level neutral-point-clamped (NPC) inverter at low modulation index. It introduces new DPWM methods in multi-level inverter and one of them is used for balancing the DC-link voltage. The current flowing in the neutral point of the DC-link causes the fluctuation of the DC-link voltage of the NPC inverter. The proposed DPWM method changes the path and duration time of the neutral point current, which makes the overall fluctuation of the DC-link voltage zero during a sampling time of the reference voltage vector. Therefore, by using the proposed strategy, the voltage of the DC-link can be balanced fairly well and the voltage ripple of the DC-link is also reduced significantly. Moreover, comparing with conventional methods which have to perform the complicated calculation, the proposed strategy is very simple. The validity of the proposed DPWM method is verified by the experiment.

Reducing Switching Losses in Indirect Matrix Converter Drives: Discontinuous PWM Method

  • Bak, Yeongsu;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.18 no.5
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    • pp.1325-1335
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    • 2018
  • This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.

A Simple Control Strategy for Balancing the DC-link Voltage of Neutral-Point-Clamped Inverters at low modulation index (Neutral-Point-Clamped 인버터의 저 변조지수에서 DC 링크 전압 균형을 위한 간단한 컨트롤 기법)

  • Ma C.S.;Kim T.J.;Kang D.W.;Hyun D.S.
    • Proceedings of the KIPE Conference
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    • 2003.07b
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    • pp.560-564
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    • 2003
  • This paper proposes a simple control strategy based on the discontinuous PWM(DPWM) to balance the DC-link voltage of three-level Neutral-Point-Clamped(WPC) inverters at low modulation index. New DPWM methods in multi-level inverter are also introduced. The proposed DPWM method changes the path and duration to flow the neutral point current out of or into neutral point of the DC-link and it makes the overall fluctuation of the DC-link voltage zero during a sampling time of reference voltage vector. Therefore, the voltage of the DC-link can be balanced fairly well and also the voltage ripple of the DC-link is reduced significantly. Moreover, comparing with conventional methods, the proposed strategy is very simple. The validity of the proposed DPWM method is verified by experiment

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Comparative analysis of efficiency and THD on SVPWM using 14.3kW 3-level NPC inverter (14.3kW급 3-레벨 NPC 인버터 각 SVPWM 효율 및 THD 비교 분석)

  • Lee, Chun-Bok;Hyun, Seung-Wook;Lee, Hee-Jun;Sin, Soo-Cheol;Kim, Young-Real;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2013.11a
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    • pp.107-108
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    • 2013
  • 본 논문에서는 3-레벨 NPC(Neutral Point Clamped) 인버터에서 사용되는 SVPWM(Space Vector Pluse Width Modulation)기법들 중 옵셋전압을 이용한 대칭 SVPWM과 효율을 높이기 위한 전압 지령 벡터를 계산한 $120^{\circ}$ DPWM(Discontinuous PWM)과 $60^{\circ}(+30^{\circ})$ DPWM을 비교 분석하였다. 각 SVPWM간의 효율 및 THD를 비교 분석 하였고 이를 통해 시뮬레이션으로 스위칭 방식에 따라 비교하여 효율 및 THD 결과를 도출하였다.

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Consideration of the Carrier Based Signal Injection Method in Three Shunt Sensing Inverters for Sensorless Motor Control

  • Jung, Sungho;Ha, Jung-Ik
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1791-1801
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    • 2016
  • This paper considers a carrier based signal injection method for use in the three shunt sensing inverter (TSSI) for sensorless motor control. It also analyzes the loss according to the injection axis of the voltage signal. To remove both the phase current and rotor position sensors, a sensorless method and a phase current reconstruction method can be simultaneously considered. However, an interaction between the two methods can be incurred when both methods inject voltage signals simultaneously. In this paper, a signal injection based sensorless method with the 120° OFF Discontinuous PWM (DPWM) is implemented in a TSSI to avoid this interaction problem. Since one leg does not have a switching event for one sampling period in the 120° OFF DPWM, the switching loss is altered according to the injection axis. The switching loss in the d-axis injection case can be up to 32% larger than that in the q-axis injection case. Other losses according to the injection axis are also analyzed.

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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