• Title/Summary/Keyword: Phase-shifted carrier

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An Improved Phase-Shifted Carrier Pulse Width Modulation Based on the Artificial Bee Colony Algorithm for Cascaded H-Bridge Multilevel Inverters

  • Cai, Xinjian;Wu, Zhenxing;Li, Quanfeng;Wang, Shuxiu
    • Journal of Power Electronics
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    • v.16 no.2
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    • pp.512-521
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    • 2016
  • Cascaded H-bridge multilevel (CHBML) inverters usually include a large number of isolated dc-voltage sources. Some faults in the dc-voltage sources result in unequal cell dc voltages. Unfortunately, the conventional phase-shifted carrier (PSC) PWM method that is widely used for CHBML inverters cannot eliminate low frequency sideband harmonics when the cell dc voltages are not equal. This paper analyzes the principle of sideband harmonic elimination, and proposes an improved PSCPWM that can eliminate low frequency sideband harmonics under the condition of unequal dc voltages. In order to calculate the carrier phases, it is necessary to solve transcendental equations for low frequency sideband harmonic elimination. Therefore, an approach based on the artificial bee colony (ABC) algorithm is presented in this paper. The proposed PSCPWM method enhances the reliability of CHBML inverters. The proposed PSCPWM is not limited to CHBML inverters. It can also be applied to other types of multilevel inverters. Simulation and experimental result obtained from a prototype CHBML inverter verify the theoretical analysis and the achievements made in this paper.

Parallel Operation Systems of Z-Source Inverters for Fuel Cell Systems (연료 전지 시스템을 위한 Z-소스 인버터고 구성된 병렬 운전 시스템)

  • Moon Hyun-Wook;Jeong Eun-Jin;Kim Yoon-Ho
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.5
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    • pp.443-449
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    • 2005
  • In this paper, parallel operation systems with Z-source Inverters for the fuel cell systems are discussed. The carrier phase shifted SPWM(Sinusoidal Pulse Width Modulation) has an advantage in reducing harmonics of output current. However when this technique applies in parallel operation of Z-source inverters, it additionally produces circulating currents. The circulating current is analyzed and a method to prevent the circulating current is applied to the parallel operation systems of Z-source inverters. To maintain high performance with reduced circulating current in inverter output and low harmonic components in load current, circulating current reactors are used. The proposed approach is verified through simulation and experiment.

Modulation, Harmonic Analysis, and Balancing Control for a New Modular Multilevel Converter

  • Li, Binbin;Zhang, Yi;Wang, Gaolin;Xu, Dianguo
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.163-172
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    • 2016
  • The modular multilevel converter (MMC) has been receiving increased attentions in recent years. The new modular multilevel converter is a derivative topology from the traditional MMC in which the number of sub-modules (SMs) necessitated by each phase can be reduced by one. This paper presents a phase-shifted carrier pulse-width modulation (PSC-PWM) for the new MMC with an optimal phase-shifted angle to suppress the harmonics of the output voltage. Further, the harmonic features when the capacitor voltage of the middle SM is selected as two different values are also investigated. Moreover, in order to avoid introducing an unnecessary dc offset current at the ac terminals of the new MMC, a novel capacitor voltage balancing scheme is proposed by adjusting the amplitude of the reference signals rather than the offset. Finally, the validity and effectiveness of the proposed modulation and balancing schemes have been verified by experimental results based on a three-phase prototype of the new MMC.

DC-link Ripple Reduction of Cascaded NPC/H-bridge Converter using Third Harmonic Injection (Cascaded NPC/H-bridge 컨버터의 DC링크 리플 저감을 위한 3차 고조파 주입 기법)

  • Park, Woo-Ho;Kang, Jin-Wook;Hyun, Seung-Wook;Hong, Seok-Jin;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2016.11a
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    • pp.218-219
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    • 2016
  • This paper present Phase Shifted with carrier based on Sinusoidal PWM(SPWM) by using Cascaded NPC/H-birdge converter. The proposed Phase Shifted PWM method is adding third harmonic injection in switching signal. The advantage of the proposed method is reducing the voltage and capacity of the capacitor. This paper compare general Phase Shifted method with proposed Phase Shifted method that added the third harmonic injection. Each PWM method is tested without considering the switching loss by using PSIM 9.1.4 simulation.

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An Improved Phase-Shifted Carrier PWM for Modular Multilevel Converters with Redundancy Sub-Modules

  • Choi, Jong-Yun;Han, Byung-Moon
    • Journal of Power Electronics
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    • v.16 no.2
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    • pp.473-479
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    • 2016
  • In this paper, the PSC PWM method is chosen as the optimal modulation method for a 20MW VSC HVDC, with consideration of the harmonic distortion of the output voltage, the switching frequency, and the control implementation difficulty. In addition, a new PSC PWM method is proposed in order to achieve an easy application and to solve the redundant control problems encountered in the previous PSC PWM method. To verify the proposed PSC PWM method, PSCAD/EMTDC simulations for an 11-level MMC RTDS HILS test and an 11-level MMC prototype converter test were performed. As can be seen from the results of these tests, the proposed PSC PWM method shows good results in an 11-level MMC with redundant sub-modules.

A Study on the Parallel Operation of a Front-end-converter for a High Speed Electric Traction Drive (고속전철 4상한 입력 컨버터 병렬 운전에 관한 연구)

  • Ryoo, Hong-Je;Woo, Myung-Ho;Kim, Jong-Soo;Kim, Won-Ho;Rim, Geun-Hie;Gopakumar, K.
    • Proceedings of the KIEE Conference
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    • 1998.11a
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    • pp.121-124
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    • 1998
  • Front end AC to DC converters of the boost type are used in traction applications for generating the DC link for the inverters. A GTO based converter is usually switched with a switching frequency of 300 to 500Hz, resulting in low frequency harmonic problems. In order to avoid this, multiple converters with Phase shifted carrier waveforms are used to suppress the low frequency harmonics. A detailed study of an AC to DC converter, with two converters parallely operated with Phase shifted carrier wave farms is Presented in this paper.

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Single-Phase Step-Up Five-Level Inverter with Phase-Shifted Pulse Width Modulation

  • Chen, Jianfei;Wang, Caisheng;Li, Jian
    • Journal of Power Electronics
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    • v.19 no.1
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    • pp.134-145
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    • 2019
  • A single-phase step-up five-level inverter topology with a new phase-shifted pulse width modulation (PS-PWM) strategy is proposed in this paper. When compared with conventional single-phase five-level inverter topologies, the proposed topology can realize multilevel inversion with a double step-up ratio, a reduced number of switching devices and self-balanced capacitor voltages. When compared with the conventional PS-PWM strategy, the new PS-PWM strategy can be implemented with one carrier reduced, which makes it much easier to implement in a digital signal processor (DSP) system. Experimental results have been presented to verify the effectiveness of the proposed inverter and the PS-PWM strategy.

An Equivalent Carrier-based Implementation of a Modified 24-Sector SVPWM Strategy for Asymmetrical Dual Stator Induction Machines

  • Wang, Kun;You, Xiaojie;Wang, Chenchen
    • Journal of Power Electronics
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    • v.16 no.4
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    • pp.1336-1345
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    • 2016
  • A modified space vector pulse width modulation (SVPWM) strategy based on vector space decomposition and its equivalent carrier-based PWM realization are proposed in this paper, which is suitable for six-phase asymmetrical dual stator induction machines (DSIMs). A DSIM is composed of two sets of symmetrical three-phase stator windings spatially shifted by 30 electrical degrees and a squirrel-cage type rotor. The proposed SVPWM technique can reduce torque ripples and suppress the harmonic currents flowing in the stator windings. Above all, the equivalent relationship between the proposed SVPWM technique and the carrier-based PWM technique has been demonstrated, which allows for easy implementation by a digital signal processor (DSP). Simulation and experimental results, carried out separately on a simulation system and a 3.0 kW DSIM prototype test bench, are presented and discussed.

A Novel Modulation Strategy Based on Level-Shifted PWM for Fault Tolerant Control of Cascaded Multilevel Inverters (Cascaded 멀티레벨 인버터의 고장 허용 제어를 위한 Level-Shifted PWM 기반의 새로운 변조 기법)

  • Kim, Seok-Min;Lee, June-Seok;Lee, Kyo-Beum
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.5
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    • pp.718-725
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    • 2015
  • This paper proposes a novel level-shifted PWM (LS-PWM) strategy for fault tolerant cascaded multilevel inverter. Most proposed fault-tolerant operation methods in many of studies are based on a phase-shifted PWM (PS-PWM) method. To apply these methods to multilevel inverter systems using LS-PWM, two additional steps will be implemented. During the occurrence of a single-inverter-cell fault, the carrier bands scheme is reconfigured and modulation levels of inverter cells are reassigned in this proposed fault-tolerant operation. The proposed strategy performs balanced three-phase line-to-line voltages and line currents when a switching device fault occurs in a cascaded multilevel inverter using LS-PWM. Simulation and experimental results are included in the paper to verify the proposed method.

A Characteristic Improvement for the Parallel Operation of Z-source Inverters (Z-소스 인버터의 병렬운전 특성 개선)

  • Kim, Yoon-Ho;Lee, Woog-Young;Seo, Kang-Moon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.3
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    • pp.56-61
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    • 2007
  • In this paper, a circulating current reduction approach for the parallel operation of fuelcell systems with Z-source inverters is investigated. The carrier phase shifted SPWM(Sinusoidal Pulse Width Modulation) is used as a modulation method since it has an advantage in reducing output current harmonics. However, when this technique is applied to the parallel operation of Z-source inverters, it additionally produces circulating currents. A coupled circulating current reactor is used to reduce circulating current generated by the parallel operation of Z-source inverters and to reduce output current harmonics. The proposed circulating current reduction approach using coupled circulating current reactors is verified through simulation and experiment.