1,721,056 research outputs found
UNIPOLAR PWM FOR TRANSFORMERLESS GRID-CONNECTED CONVERTERS IN PHOTOVOLTAIC PLANTS
No full textIn domestic grid connected PV applications a single phase converter is usually used. In such a low power plants it is possible to adopt converter topology with no galvanic isolation between the photovoltaic panels and the grid. The absence of a high or low frequency transformer permits to reduce power losses, cost and size of the converter. On the other side in presence of a galvanic connection a large leakage ground current could arise due to parasitic PV panel capacitance. This leakage current causes electric safety problems, an increase of EMI and a reduction of the power quality. This paper presents a converter topology based on unipolar PWM modulation able to minimize the leakage ground current locking the common output voltage to VDC/2 as the converters topology based on bipolar modulation do. Simulation results show the effectiveness of the proposed topology. Eventually a comparison of the power losses of the proposed architecture with respect to some established topologies is presented
Stability and performance analysis of a voltage controlled resistor circuit for wide band-gap device gate drivers
No full textWide band-gap devices are making inroads in the power converters scenario, and specific circuits to drive these components are actively under development. The purpose of this paper is to analyze, from the stability and dynamic performance point of view, a Voltage Controlled Power Resistor (VCPR), that can be used to control the gate resistance of the device driver with values over a continuous range. Parametric analysis, SPICE simulations and experimental outcomes are presented, in order to determine circuit characteristics. Results show that the proposed topology is stable under a wide range of electric parameters, and suggest that the circuit bandwidth can be tuned in order to benefit from the VCPR in a wide band-gap device gate driver
Analysis of Externally Excited Synchronous Motors Operation Under Joule Losses Minimization Control
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On the AC Losses in the End Conductors of Hairpin Windings
Full text linkIn the last years, several resources have been employed to increase torque and power density values in electrical machines, especially in those intended for transport applications. In this context, the adoption of hairpin conductors is spreading thanks to their inherently high fill factor. Their main drawback is represented by their sensitivity to high-frequency phenomena, which can have a significant impact on the Joule losses and thus on the overall efficiency.
While several researches have recently focused on ways to model and reduce such high-frequency losses in the slots, i.e. within the conductors’ active sides, a few data are available on their impact in the end winding regions.
This work provides an investigation on the AC losses occurring in the end conductors of a hairpin winding traction motor. The losses are determined through 3D finite element simulations for a wide frequency range, and compared against those occurring in the active part of the machine.
© 20XX IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper reflects only the author's view. JU is not responsible for any use that may be made of the information it contains
Guest Editorial: High Sustainable Electric Drives for Transportation Electrification
Full text linkGiven that nearly 23% of global CO2 emissions is blamed on the transport sector, its electrification becomes crucial for reaching the 2050 Net Zero Emissions scenario. The key enabler to this purpose is a sustainable design and development of electric power train systems, aiming at cutting the overall greenhouse gases emissions during each of the different life-cycle stages of the design, including procurement, manufacturing, use, and recycle or reuse.This introduces new challenges in the design of batteries, power converters, and electric motors, which must now prioritize environmental sustainability without compromising key performance metrics, such as power density, efficiency, cost, and reliability
Analysis of Voltage Distribution and Connections within a High-Frequency Hairpin Winding Model
Full text linkIn the last years the adoption of hairpin windings is increasing, especially in the automotive sector, mainly due to their inherently high fill factor and electric loading capability.
A critical aspect related to the reliability and lifetime of every winding typology is the voltage stress due to the uneven voltage distribution. This phenomenon has already been largely analyzed in conventional stranded conductors, while a few studies are available for hairpin windings. With the spreading of wide bandgap devices, the investigation on voltage distribution becomes an ever-timely topic due to their short rise times. This paper presents an analysis of the uneven voltage distribution triggered within hairpin windings by a low rise time waveform, using a complete high-frequency winding model. The different options to series-connect different paths are investigated, providing simple but essential guidelines to reduce the electrical stress within hairpin windings.
© 20XX IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper reflects only the author's view. JU is not responsible for any use that may be made of the information it contains
Hairpin Windings: An Opportunity for Next-Generation E-Motors in Transportation
Full text linkAdvances in electrical machines and power electronics (PEs) are helping to achieve the power density and efficiency required by the transportation sector. However, the reliability of components and production processes is a challenge. This is especially true for electrical machines, whose winding processes are far from the high levels of automation, programmability, and repeatability that are required. This article looks into hairpin windings and outlines a number of future actions to address challenges and eventually enable the complete penetration of hairpin windings in transportation
Multi-stress lifetime model of the winding insulation of electrical machines
No full textIn this paper, a novel multi-stress model which estimates the lifetime of the winding insulation relative to its duty cycle is proposed and investigated. With an adequate implementation of this model, then an electrical machine can be designed not only in terms of its performance requirements, but also considering the associated reliability and lifetime aspects. The determination of the model parameters is based on the results of accelerated thermo-mechanical ageing tests
Single-phase series active power filter with transformer-coupled matrix converter
Full text linkThis study presents a series active power filter based on a single-phase matrix converter. Back-to-back voltagesource converters with nested control loops and passive filters are normally used for this application. A matrix converter, as proposed in this study, allows a simpler implementation both in terms of hardware (no grid filter and no DC link) and of control. Moreover, a novel zero-voltage compensation technique is introduced in order to reduce the distortion around the input voltage zero crossing. Simulations and experiments are used to validate the considered control methods, confirming the feasibility of the proposed architecture
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