Introduction to Modern Power Electronics

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Detection of Mechanical Abnormalities in Induction Motors by Electric Measurements

The paper gives an overview of the issues and means of detection of mechanical abnormalities in induction motors by electric measurements. If undetected and untreated, the worn or damaged bearings, rotor imbalance and eccentricity, broken bars of the rotor cage, and torsional and lateral vibration lead to roughly a half of all failures of induction motor drives. The detection of abnormalities is based on the fact that they cause periodic disturbance of motor variables, such as the speed, torque, current, and magnetic flux. Thus, spectral analysis of those or related quantities may yield a warning about an incipient failure of the drive system. Although the traditional non-invasive diagnostics has mostly been based on the signature analysis of the stator current, other media can also be employed. In particular, the partial instantaneous input power is shown, theoretically and experimentally, to offer distinct advantages under noisy operating conditions. Use of torque and flux estimates is also discussed

Introduction to modern power elctronics

Indeks *** *** Bibliografi hlm. Setiap babx, 433 hlm. : il. ; 23 cm

Phase Shifting Transformer-LCL (PST-LCL) Filter: Modeling and Analysis

International audiencePower converters have been widely used in power systems to improve the quality and magnitude of the power drawn from renewable energy sources. An LCL filter for connection of an inverter to the grid is often used to reduce the harmonics generated by the inverter. Based on the different design methodologies, optimal parameters of LCL filters tend to differ in wide ranges. This paper proposes a new approach to an LCL filter used for decreasing the harmonic currents. A phase shifting transformer is added into the structure of an LCL filter to mitigate the harmonic current. The procedures and techniques described in this paper are particularly suitable for the grid-connected photovoltaic energy systems

Harmonic Mitigation in Three-Phase Power Networks with Photovoltaic Energy Sources

International audienceEnergy systems based on photovoltaic (PV) cells have increased at a rapid pace. Therefore, power converters have been widely employed in power systems to enhance the quality and magnitude of the power drawn from renewable energy sources. An LCL filter for connection of an inverter to the grid is often used to reduce harmonics generated by the inverter. According to different design techniques, optimal parameters of LCL filter tend to vary in a wide range. This paper presents a new approach to an LCL filter. A phase shifting transformer placed in the structure of an LCL filter to minimize harmonic current. Methods and techniques described in this paper are particularly suitable for grid-connected PV power systems

A 3-3 quasi Z-source matrix converter for residential wind energy systems

When compared to the Z-source inverter, the quasi Z-source inverter offers several advantages, including lower component ratings, reduced source stress and switch count, and simpler control strategies. In this study, the concept of a quasi Z-source network is extended on a 3-3 indirect matrix converter. The converter, destined for residential wind energy systems, is based on the ultra-sparse matrix topology characterized by the minimum number of semiconductor switches. The quasi Z-source network is placed between the three-switch input rectifier stage and the output six-switch inverter stage. © 2012 IEEE

A comparative study of series and cascaded z-source matrix converters

The series Z-source network, an expansion of the popular concept of the Z-source dc link, was originally proposed for boosting the output voltage of power electronic inverters. In this paper, that idea is extended on a three-phase indirect matrix converter. The converter is based on the ultrasparse matrix topology characterized by the minimum number of semiconductor switches. The series Z-source network is placed between the three-switch input rectifier stage and the six-switch output inverter stage in either the positive or the negative rail. A brief shoot-through state produces the voltage boost. An optimal pulsewidth modulation (PWM) technique is developed for higher boosting capability of the converter and minimization of switching losses. A comparison is made between the matrix converters employing series and conventional cascade Z-source networks. The inrush current and Z-source capacitor\u27s voltage are reduced in the series Z-source matrix converter. Furthermore, the fast Fourier transform analysis of the output current of the converters suggests superiority of the series Z-source matrix converter over the cascaded Z-source matrix converter. © 2014 IEEE