1,721,132 research outputs found
Common- and differential- mode HF current components in AC motors supplied by voltage source inverters
No full textIn this paper, an inverter-fed ac motor drive is analyzed in order to investigate the conducted electromagnetic interferences at both the input and output sides of the inverter. HF lumped equivalent circuits for the inverter and the motor stator windings are proposed. The overall circuit model allows time- and frequency-domain analysis to be performed with standard circuit simulators. The proposed model can also predict common- and differential-mode HF current components. The equivalent circuit is verified by experimental tests carried out on a prototype of ac motor drive
Double-Inverter Drive System for Electric Ship Propulsion
No full textIn this paper a new electric ship propulsion system is proposed as combination of a double generator set with a double inverter feeding a wound-rotor synchronous machine.
Each generator set is composed by a diesel engine directly coupled to a compact, permanent magnet, synchronous generator. A diode rectifier connects the output of the generator to a variable voltage dc bus. The dc bus feeds one of the input sides of the double inverter. The double inverter acts as a multilevel converter and it is able to drive the 3-phase, 6-wire motor coupled to the propeller. The two generator sets can operate either jointly or one at a time,
depending on the power demand from the drive system. The working point of each diesel engine is determined in order to supply power to the propeller with maximum efficiency
Effects of input voltage measurement on stability of matrix converter drive system
No full textThe effects of different input voltage measurement methods on the stability of a matrix converter drive system are analysed. In particular, with the aim of improving the maximum output power of the matrix converter, the duty cycles of the switching configurations are calculated using input voltages filtered by a digital lowpass filter. A variable state average model of the whole system, which takes into account the grid impedance, the input L–C filter parameters and the load, is used for the theoretical analysis. The stability of the system is evaluated by analysing the migration of eigenvalues of the system, which is linearised around a steady-state operating point. The analytical approach allows the determination of the maximum power for a stable operation of the matrix converter as a function of the time constant of the digital lowpass input voltage filter. Theoretical considerations are supported by simulation results, showing the varying behaviour of the matrix converter that can be achieved in terms of stability as the time constant of the digital filter is changed
Modeling and Simulation of Grid Connected Wind Energy Conversion System Based on a Doubly Fed Induction Generator (DFIG)
No full textThis paper deals with the analysis, modeling, and control of a grid connected doubly-fed induction generator (DFIG) driven by the wind turbine. Recent advancements in size and technology of wind turbines require sophisticated control systems to effectively optimize energy conversion and enhance grid integration. This article investigates the power flow analysis of grid connected Wind Energy Conversion System (WECS) in a highly fluctuating wind environment. The WECS is equipped with a DFIG and a back-to-back converter in the rotor circuit. A control technique is presented for extracting the maximum power from the wind turbine. The grid side converter maintains the DC link voltage and the task of the rotor side converter is to track the maximum power point for the wind turbine. The description for the proposed system is presented with the detailed dynamic modeling equations. Simulation results for different operating conditions are presented
Management of multi-drive powertrain for full electric vehicle in degraded operating conditions
No full textThis paper deals with the development of force splitting strategies to be used within the computation of the force reference in multi-drive electric powertrains. Under normal operating conditions the total force is divided between the drives according to a desired behavior for better performance or energy consumption. The proposed algorithms take into account possible malfunctions which may reduce the tractive force of one or more drives, thus affecting the output sharing principle. For a number of degraded working conditions, several correction strategies have been implemented, with the aim of minimizing the impact of drive anomalies on the vehicle's behavior and the driver's feeling
Mixed Stator-Rotor fault characterization for Doubly Fed Induction Machines
No full textThis paper introduces a diagnostic technique for the detection of mixed Stator-Rotor electrical faults in Doubly Fed Induction Machine (DFIM) for wind power systems. Operating in aggressive environments, the detection of anomalies at an incipient stage is crucial to decide about the operating continuity of the machines. In this paper the behavior of DFIM is investigated under the assumption that the stator and rotor windings are simultaneously unbalanced owing to faults or incipient windings damage. The aim of the presented work is to investigate the spectral signature frequencies issued from stator and rotor currents under mixed stator-rotor asymmetry. The derived chains of interhamonics are firstly validated by numerical simulations, and then by experimental tests with a 5.5 kW wound rotor induction motor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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