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ECOLOGICAL POWER SYSTEM WITH LOCAL DISTRIBUTION DC-LINE FOR AC-DRIVE CONSUMERS

IFAC Proceedings Volumes 2007年第8期40卷 71-76页

作者： Maria IMECS Ioan Iov INCZE Csaba SZABó University of Cluj-Napoca Romania

The paper deals with the simulation and implementation of AC-drives with synchronous and induction motors fed by a local distribution DC-line, which is supplied from an autonomous vector controlled synchronous generator. The main AC-grid is connected to DC-line the via ecological power electronic converters with bi-directional power flow, like the AC-drives and the generator. Solutions are proposed for sine-wave rectifying and inverting of the energy accomplishing grid-side unity power-factor with active power-filtering of the AC-grid- and motorside currents for different transferred energy levels. The energy-efficiency of the drives is achieved by means of vector control structures.

关键词： Active filters Converters pulse-width modulation Drives Ecology Electric power systems Induction motors Motor control Synchronous machines Simulation

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Carrier-based control of matrix converter in linear and over-modulation modes 07

Carrier-based control of matrix converter in linear and over...

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Proceedings of the 2007 Summer Computer Simulation Conference

作者： T. Satish K. K. Mohapatra Ned Mohan University of Minnesota Minneapolis MN

ISBN: (纸本)9781565553163

Since the inception of matrix converters, various modulation schemes have been proposed for their control. But the explanation of matrix converter operation is complex, and so is the control methodology. In this paper a 3-phase to 3-phase matrix converter is explained from the point of view of multi-level inverter topology. The matrix converter is represented as a three-level inverter and a switching cycle average model of the converter is presented. A simplified carrier-based modulation scheme is proposed where the need for sector information and corresponding look-up tables is avoided. The theoretical maximum output to input voltage transfer ratio of 0.866 is attained when the input power factor is unity. The voltage transfer-ratio is increased at the expense of low frequency harmonic distortion in the output voltages and input currents, by operating the converter in the over-modulation mode. Both input-side over-modulation and output-side over-modulation are analyzed and their limits of operation are derived. The voltage transfer-ratio is found to be 0.95 with output-side over-modulation and 0.908 with input-side over-modulation. Theoretical calculations of the maximum output voltages in the linear and over-modulation modes presented in the paper are supported by simulation results.

关键词： matrix converter over-modulation pulse-width modulation

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Diode-Assisted Buck-Boost Current Source Inverters

Diode-Assisted Buck-Boost Current Source Inverters

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2007 International Conference on Power Electronics and Drive Systems (PEDS 2007), vol,3

作者： F. Gao C. Liang P. C. Loh F. Blaabjerg School of Electrical and Electronic Engineering Nanyang Technological University Singapore School of Electrical and Electronic Engineering Nanyang Technological University Singapore Singapore Institute of Energy Technology Aalborg University Denmark Denmark

This paper presents a couple of novel current source inverters (CSIs) with the enhanced current buck-boost capability. With the unique diode-inductor network added between current source inverter circuitry and current boost elements, the proposed buck-boost current source inverters demonstrate a double current boost capability when comparing with the recently reported buck-boost CSIs. For modulating the presented CSIs, two modulation schemes are proposed for achieving either optimized harmonic performance or minimal commutation count, meanwhile keeping the important current buck-boost operation uninfluenced. Lastly, all theoretical findings were verified experimentally using constructed laboratory prototypes.

关键词： Buck-boost Current source inverter pulse-width modulation

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Comprehensive study on space-vector-PWM and carrier-based-PWM correlation in multilevel invertors

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IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 2006年第1期153卷 149-158页

作者： Nho, NV Youn, MJ HochiminhCity Univ Technol Dept Elect Engn Ho Chi Minh City Vietnam Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea

The paper presents a theoretical analysis of the correlation between carrier-based unipolar PWM (CPWM) and space-vector PWM (SVPWM) For the entire modulation-index range of multilevel invertors, including overmodulation. By presenting corresponding parameters of vector redundancies in a zero-sequence function, the carrier-based PWM has matched the SVPWM technique. Carrier-SVPWM and discontinuous-PWM methods capable of obtaining any approximate Optimum offset are proposed. Among them, the minimum-common-mode PWM methods can attain a proper balancing of switching loss. A unified Unipolar carrier PWM modulator is presented. Different PWM modes and the offset value can be controlled in an offset generator. Without a look-up table, linear overmodulation can be implemented simply in an active signal generator. The correlations and proposed PWM methods have been analysed mathematically and demonstrated by simulations.

关键词： pulse-width modulation modulation (Electronics) SWITCHING circuits SIGNAL generators SIMULATION methods & models ELECTRIC potential

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Study of the mechanism of overlays acting on laser shock waves

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JOURNAL OF APPLIED PHYSICS 2006年第10期100卷 103517-103517-6页

作者： Zhang, Yongkang Gu, Yongyu Zhang, Xingquan Shi, Jianguo Zhou, Jun Jiangsu Univ Sch Mech Engn Zhenjiang 212013 Peoples R China E China Univ Sci & Technol Sch Mech & Power Engn Shanghai 200237 Peoples R China

In laser shock processing, overlays are used to enhance peak pressures and prolong pulse widths of laser shock waves. The overlay usually has three types: rigid, flexible, and liquid overlays. In this paper, some mathematical models are constructed to analyze the process of laser-induced shock waves and pressure attenuations of the shock waves. The analyses indicate that the peak pressure of shock waves depends on the deformation amount of the overlays and the pressure attenuations depend on the deformation speed of the overlays, while the deformation amount and deformation speed are determined by the density and thickness of the overlays. Besides, for the rigid overlay, the elastic modulus must be taken into account in addition to its density and thickness. Furthermore, the reflected waves from the overlays enhance the shocking effects of laser-induced shock waves. Therefore, the rigid overlays are superior to the flexible and liquid overlays. (c) 2006 American Institute of Physics.

关键词： SHOCK waves LASER materials pulse-width modulation ELASTIC analysis (Engineering) DEFORMATIONS (Mechanics) ATTENUATION (Physics)

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Photoepilation results of axillary hair in dark-skinned patients by IPL: A comparison between different wavelength and pulse width

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DERMATOLOGIC SURGERY 2006年第2期32卷 234-240页

作者： Lee, JH Huh, CH Yoon, HJ Cho, KH Chung, JH Seoul Natl Univ Coll Med Dept Dermatol Seoul 110744 South Korea

BACKGROUND Recently, intense pulsed light (IPL) sources have been shown to provide long-term hair removal. OBJECTIVE This study examined the photoepilatory effects of different wavelengths and pulse width application, in the same device and compared their efficiencies in Asian skin. METHODS Twenty-eight Korean women were treated using HR (600-950 nm filter) and 27 using HR-D (645-950 nm filter) in the axillar area. Four treatments were carried out at intervals of 4 to 6 weeks;follow-ups were conducted 8 months after the last treatment. Mean energy settings were 14.9 +/- 2.0 J/cm(2) for HR and 17.1 +/- 0.6 J/cm(2) for HR-D. Longer pulse widths were applied in case of HR-D treatment. Hair counts and photographic evaluation of skin sites were made at baseline and at the last follow-up. Final overall evaluations were performed by patients and clinicians. RESULTS Average clearances of 52.8% and 83.4% were achieved by HR and HR-D, respectively. No significant adverse effects were reported after HR-D treatment. One case each of hypopigmentation and hyperpigmentation was reported for HR. CONCLUSION An IPL source by removing 45 nm of the emitted spectra and applying longer pulse width was found to provide a safer and more effective means of photoepilation in Asian patients.

关键词： HAIR removal ELECTROLYSIS in surgery HUMAN skin color ASIANS EMISSION spectroscopy pulse-width modulation

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Analysis and implementation of three-phase power quality compensator under the balanced and unbalanced load conditions

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ELECTRIC POWER SYSTEMS RESEARCH 2006年第5期76卷 271-282页

作者： Lin, BR Yang, TY Natl Yunlin Univ Sci & Technol Dept Elect Engn Power Elect Res Lab Yunlin 640 Taiwan

An active power filter with asymmetric inverter legs are presented to eliminate harmonics, compensate reactive power and draw the balanced line current from the AC source under balanced and unbalanced load conditions. Three inverter legs are used in the adopted voltage source inverter. In each leg, four active switches are adopted to achieve three-level pulse-width modulation (PWM). No clamped diode or flying capacitor is used in the proposed inverter. In the adopted control algorithm, a classical proportional-integral voltage controller and hysteresis current controller are used to maintain DC-link voltage constant and to track line current commands, respectively. A voltage compensator is added in the inner control loop to compensate the neutral point voltage variation due to load variation. Based on the proposed PWM control scheme, a three-level voltage pattern is generated on the AC terminal of the inverter. The system configuration and mathematical analysis are discussed in the paper. Finally, the experimental results based on a laboratory scaled down prototype are provided to verify the effectiveness of the control algorithm. (c) 2005 Published by Elsevier B.V.

关键词： voltage and current controller pulse-width modulation inverter

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Implementation and simulation of modified PWM with two current control techniques applied to single-phase shunt hybrid power filter

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IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 2006年第3期153卷 317-326页

作者： Rahmani, S. Al-Haddad, K. Kanaan, H. Y. Singh, B. Ecole Technol Super Canada Res Chair Energy Convers & Power Elect CRC ECPE Montreal PQ H3C 1K3 Canada

Filter and source current control strategies are applied to a single-phase shunt hybrid power filter (SPSHPF). These techniques are implemented with a modified pulse width modulation (M-PWM) in order to compensate for the harmonics and reactive power required by nonlinear loads and the high-frequency harmonics generated by the switching process. Contrarily to the existing methods, the proposed source current control eliminates switching spikes in the supply current and appears to be more suitable than the filter current control method. Furthermore, the M-PWM technique ensures the elimination of all groups of harmonics that are centred on the odd multiples of the switching frequency. It requires a relatively reduced size input passive filter. In addition, it attenuates the harmonics that are located around twice the switching frequency four times less than the S-PWM. The measured power losses of the M-PWM hybrid filter are also one-fourth compared to that of the standard PWM control. Experimental results obtained on a 1 kVA developed laboratory prototype system and through simulations validate the effectiveness of the SPSHPF adopting the source current control with the modified PWM technique.

关键词： pulse-width modulation ELECTRIC filters HARMONICS (Electric waves) REACTIVE power (Electrical engineering) ELECTRIC currents

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Buck-boost thyristor-based PWM current-source inverter

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IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 2006年第5期153卷 664-672页

作者： Loh, P. C. Nanyang Technol Univ Sch Elect & Elect Engn Gen Off B Singapore 639798 Singapore

The traditional thyristor-based current-source inverter (CSI) has been reported for use in synchronous motor drives and utility-grid-interfacing systems, where its inherent output short-circuit protection and direct-current control have been added advantages. Despite these advantages, the thyristor-based CSI is known to suffer from poor waveform quality owing to its low-frequency six-step switching and only step-up (boost) operation. Both disadvantages severely constrain the use of thyristor-based CSI for utility interfacing, especially when the inverter input is fed from renewable-energy sources whose outputs vary continuously. To address the above limitations, the paper proposes the design of a buck-boost thyristor-based CSI with pulse-width-modulated (PWM) control. This CSI uses a unique X-shaped LC impedance network connected to its DC link for current-boosting and a controlled switch for actively commutating its main thyristor devices using an appropriately designed digital PWM scheme. The inverter is tested experimentally using a laboratory prototype, and is shown to perform smooth DC-AC current conversion, making it a competitive solution for both utility and industry applications.

关键词： THYRISTOR converters pulse-width modulation ELECTRIC inverters DIGITAL electronics ELECTRONIC control POWER electronics ELECTRICAL engineering

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Quasi-resonant dc-link soft-switching PWM inverter with active feedback clamp circuit for motor drive applications

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IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 2006年第1期153卷 75-82页

作者： Shukla, J Fernandes, BG Indian Inst Technol Dept Elect Engn Bombay 400076 Maharashtra India

A novel soft-switched quasi-resonant dc-link (QRDCL) inverter topology is derived using the concept of all auxiliary switch-assisted soft-switcher (AASS) employing the flying capacitor. This concept is known for its high efficiency at high power levels, and is used for soft-switching the boost switch in zero-voltage transition (ZVT) power factor correction (PFC) boost rectifiers. Also, an active clamp circuit configuration to clamp the dc-link and recover the energy stored in the clamp capacitor is introduced and is applied to the proposed inverter topology. The resultant inverter configuration gives high efficiency and is suitable for high power motor drive applications. The maximum dc-link voltage is clamped at around (1.05-1.1) times the input dc-source voltage. The proposed inverter is suitable for pulse width modulation (PWM) operation. A detailed analysis along with the design procedure of the proposed inverter is presented. Simulation and laboratory experiments are carried out to validate the analysis.

关键词： ELECTRIC inverters CAPACITORS ELECTRIC potential pulse-width modulation DIODES SWITCHING circuits

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