1,721,047 research outputs found
Electric drives for hybrid electric agricultural tractors
No full textThis paper provides a comprehensive overview on the main features of electric drives for hybrid electric agricultural tractors. Challenges regarding the design of electric machines and power converters for this application will be deeply discussed, and feasible proposals will be presented considering state-of-the-art electric power systems for automotive applications and heavy-duty working vehicles
Dv/Dt Filtering Techniques for Electric Drives: Review and Challenges
No full textThe use of wide band gap devices in power converters is becoming more and more popular since they enable operations at higher switching frequencies, voltages and temperatures compared to traditional power semiconductors, while also improving the efficiency. However, in electric drives, they also tend to increase voltage overshoots at motor terminals and to produce uneven voltage distributions across stator windings, due to their high rate of voltage change over time (dv/dt). In order to mitigate these issues, passive filters can be employed. The aim of this paper is to give an overview of possible solutions based on passive filters, analyzing the main advantages and drawbacks. A comprehensive, qualitative comparative study is carried out taking into account common mode currents reduction, power losses, costs, dimensions and reliability
Multi three-phase hairpin windings for high-speed electrical machine: Possible implementations
Full text linkThis work provides an in-depth critical analysis related to the feasibility of combining multi three-phase winding layouts with the ever-spreading hairpin technology. After an introduction on the advantages and challenges of both hairpin and multi-phase windings, more details on how these two technologies can be combined are provided. Then two similar stator geometries, with 72 and 96 slots, are analyzed in detail exploiting an 8 poles permanent magnet - assisted synchronous reluctance motor for traction applications. A relevant set of feasible winding configurations are modelled and analyzed through finite element simulations. For every machine, a breakdown of the power losses is provided and compared against that of the same machine topologies having random-wound windings with stranded round conductors. The main results and possible solutions to increase the machine performance are then provided
Investigation of Resistivity Impact on AC Losses in Hairpin Conductors
Full text linkThis work provides an analysis of the impact on AC losses in hairpin conductors, provided by different values of resistivity. Starting from some specific stator geometries, the optimal resistivity which minimizes the AC losses is calculated for each configuration through both analytical and finite element (FE) methods, considering a frequency range typical of automotive applications. Possible applications and conditions where a higher resistivity material, such as aluminum, can be adopted, are discussed. The main sources of discrepancies between the analytical and simulative approach are also discussed
Sensitivity analysis on the voltage distribution within windings of electrical machines fed by wide band gap converters
Full text linkIn the last years, Wide Band Gap devices are seeing a significant widespread in electric drives, due to their higher performance compared to conventional semiconductors. However, they also produce higher electric stress due to over-voltages and uneven voltage distributions among winding turns of electrical machines fed by them, which can lead to premature failures and/or reduced lifetimes.This paper presents a sensitivity analysis on the voltage distribution across stator winding turns of an electric motor intended for aerospace applications. The effects of the surge voltage characteristic parameters, such as dv/dt, voltage magnitude and parasitic impedances, are investigated. An equivalent circuit approach, based on the multi-transmission line theory, is developed and implemented in MatLab-Simulink environment, while the relevant circuital parameters are estimated through finite element analysis performed with MagNet and ElecNet software
FemtoCore enabled quasi-distributed Control for Modular Multilevel Converters
No full textThe development of the processing capability has enabled the implementation of advanced control systems for power electronics converters. In this framework, the modular multilevel converter has attracted the attention of industry and academia, thanks to the good performance in terms of power quality, wide voltage capability, and fault tolerance, which are key requirement for high power applications. This paper proposes a quasi distribute control architecture based on a FemtoCore platform, an optimized soft-core designed for modular power electronics applications. Latency estimates and simulation results shows the potential of this solution for the control of modular multilevel converters
An Asymmetrical Additively Manufactured Hairpin Winding for increased efficiency and sustainability
No full textA Novel Modular Data Acquisition System for Distributed Monitoring of Partial Discharge in Industrial Drives
No full textInsulation fault detection in rotating machinery using Partial Discharge (PD) has been a hot research topic over the last decades. In recent years, attention has also been paid to low voltage machines, following the advent of wide bandgap semiconductor devices. However, most of the solutions currently available are based on analog technology, which entails high costs, bulky wiring, and long installation times, making them unattractive for the market. This paper presents a low-cost, modular, and full-digital PD monitoring device, which implements a Capacitive Coupling (CC) front end for PD conditioning and an innovative, digital monitoring network, based on the Automotive Audio Bus (A2B), particularly suitable for deployment in large industrial plants, ensuring complete coverage and continuous monitoring of critical machinery without suffering of electromagnetic disturbances. The proposed system has been simulated in PSpice, then built and tested against a reference, consisting of a laboratory grade oscilloscope, using two different PD interfaces: CC and High Frequency Current transformer (HF-C). The comparison was carried out by subjecting a low voltage induction motor to a standard PD test to evaluate PD inception voltage detection with the different methods. The digital oscilloscope demonstrated a slightly better sensitivity concerning the onset PD voltage threshold, 1.3 - 1.35 kV. The proposed monitoring device on the other hand exhibits a greater robustness at transition voltages, being less prone to false positives. The two systems are equivalent at 1.4 kV while the proposed solution performs significantly better at higher voltages, with 6 PD events per cycle detected at 1.5 kV in place of 3. The HF-C transducer demonstrated even greater sensitivity at these voltage levels, with 7.6 PD detections per cycle at 1.5 kV. The results show that the proposed PD CC sensor has satisfactory sensitivity towards detecting onset of PD activity and appears less susceptible to noise than the digital oscilloscope CC sensor
PWM impacts on the Reliability of DC/DC Converters with High-Frequency Transformer
No full textIn the framework of the More Electric Aircraft, high efficiency and high reliability are the main concerns. Different standard exists regarding voltage and frequency of the electrical power distribution system, but DC systems are attracting an increased interest. In this context, the voltage conversion is normally implemented by means of a high-frequency isolated DC/DC power converters. However, the high-frequency waveforms generated by the power electronics may trigger partial discharge phenomena in the windings of the transformer, decreasing the reliability. This paper attempts to model the lifetime of a Dual Active Bridge (DAB) converter for aerospace applications
Aluminum Hairpin Solution for Electrical Machines in E-Mobility Applications : Part I: Electromagnetic Aspects
No full textAlong with efficiency and performance, one of the main aspects of nowadays electric machines design is sustainability, especially when it comes to the transition period the automotive field is dealing with and the focus placed on electrification. This paper aims at lowering the environmental load of the electric machines, replacing copper hairpin stator windings with aluminum ones. This work compares the traditional copper hairpin design with aluminum hairpin solutions, resulted from a multi-objective genetic algorithm optimization. The optimization process has been performed with the aim of minimizing the losses as well as the utilization of rare-earth permanent magnets. Finally, the feasibility of such alternative design is evaluated from a thermal perspective, proposing potential layout of the cooling system for the selected design proposal. The paper first part is dedicated however to the electromagnetic aspects of the design with Aluminum hairpin as well as the optimization process employed. Finally, a comparison with respect to the copper solution in terms of efficiency, cost, weight and sustainability has been drawn
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