1,721,041 research outputs found
A Novel BLDC-Like DTC Control Technique for Induction Motors
Full text linkDC brushless motors are widely adopted for their simplicity of control, even in sensorless configuration, and their high torque
density. On the other hand, induction motors are very economical due to the absence of permanent magnets; for the same reason
they can easily be driven in the flux-weakening region to attain a wide speed range. Nevertheless, high dynamic induction motors
drives, based on field-oriented (FOC) or predictive control, require large amounts of computing power and are rather sensitive to
motor parameter variations. This paper presents a simple DTC induction motor control algorithm based on a well-known BLDC
control technique, which allows to realize a high dynamic induction motor speed control with wide speed range. The firmware
implementation is very compact and occupies a low amount of program memory, comparable to volt-per-Hertz- (V/f-) based
control algorithms. The novel control algorithm presents also good performance and low current ripple and can be implemented
on a low-cost motion control DSP without resorting to high-frequency PWM
Differential diagnosis based on multivariable monitoring to assess induction machine rotor conditions
No full textMultivariable supervision systems for online monitoring of induction motors allow large versatility and diagnosis robustness. As regards rotor faults, the diagnostic procedure based on sideband current components may fail due to the presence of interbar currents that reduce the degree of rotor asymmetry and, thus, the amplitude of these spectral components. On the other hand, the interbar currents produce core vibrations in the axial direction; these vibrations can be detected using a suitable vibration sensor. In this paper, a differential fault analysis based on traditional motor current signature analysis (MCSA) and on radial and axial vibration monitoring is proposed to discern cases in which the presence of interbar currents decreases the sensitivity of MCSA. The features of stator currents and of radial and axial core vibration signals are investigated in order to increase the reliability of the diagnostic system. Moreover, to explore the possibility of obtaining further information, stray flux signals are taken into account. © 2008 IEEE
Bidirectional Bootstrapped Gate Driver for High-density SiC-based Automotive DC/DC Converters
No full textSensorless Control of BLDC Motors at Low Speed Based on Differential BEMF Measurement
No full textBLDC drives are widely employed in industry due to their intrinsic robustness and high torque-to-weight ratio. The availability of cheap embedded processing power in recent years paved the way for the widespread use of sensorless control techniques; the removal of speed and position sensors leads to substantial increase of robustness and cost savings. Nevertheless, traditional sensorless BLDC control techniques suffer from low efficiency at low speed due to degraded signal to noise ratio on feedback signals and low dynamic response.
This paper describes a novel sensorless control algorithm based on a differential measurement, which allows higher dynamic performance and lower minimum operating speed with respect to traditional techniques without requiring dedicated hardware solutions or complex calculations
Vibrationless alignment algorithm for incremental encoder based BLDC drives
No full textIncremental encoder based BLDC drives are widely employed in industry whenever smooth and efficient operation is needed in the whole speed range. Their weak spot lies in the need for a phase of initial alignment. Such task is traditionally performed by forcing the motor through a series of fixed phase supply configurations, causing strong vibrations which can be intolerable for certain applications. In this paper a novel algorithm that allows determining the initial rotor position (sector) and aligning the encoder while minimizing vibrations and oscillations is presented. © 2009 IEEE
Towards practical quantification of induction drives mixed eccentricity
No full textAs far as industrial applications of induction drives are concerned, one of the most critical issues is the statement of acceptable mixed eccentricity degree and of other mechanical abnormal conditions. These troubles cause characteristic spectral components in many drive quantities, but for economic reasons the electrical quantities, already sensed for drive control purposes, are preferable; among them current signals (i.e. MCSA) are the electric signals of choice to detect the machine conditions. Each trouble produces spectral lines at typical frequencies in the stator current: monitoring them is a usual procedure but the threshold to discern acceptable intrinsic defects from alarming situations is hardly defined. This paper presents an attempt to formulate a mixed eccentricity index developed through the interaction between static and dynamic eccentricity on stator windings and rotor cage. The index can be detected by a no-load test without any spectral resolution problem and it does not require any preliminary knowledge of machine health condition. © 2009 IEEE
A geometrical interpretation of current space vector components due to induction machines rotor faults
No full textThis paper presents a deep investigation on the rotor fault signatures of induction machines. Phase current and current space vector sidebands, spectral components of flux, torque and speed are analyzed as functions of inertia, load and machine size. Analytical expressions among the physical quantities, validated by simulation and experimental results, are developed using a synchronous reference frame. These expressions, together with geometrical loci showing the vector relationships among the quantities involved, allow a thorough understanding of the underlying physical phenomena. A test-bed able to realize a variable virtual inertia allows the experimental validation as well. © 2011 IEEE
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
H8 inverter for common-mode voltage reduction in electric drives
Full text linkThis paper presents a modified two-level three-phase inverter for the reduction of the leakage current. With respect to a traditional two-level inverter, the proposed solution reduces the common-mode voltage (CMV), both in amplitude and frequency. Between the dc source and the traditional three-phase bridge, two active dc-decoupling devices and a voltage-clamping network have been added. A dedicated control strategy was developed adopting a modified space vector pulse-width modulation, oriented to the reduction of the CMV. Simulations showing the good performance of the solution are presented. A preliminary prototype was developed and experimental results are presented
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