Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"Line current"”.
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The monitoring of induction motor starting transients with a view to early fault detection.
… motor by monitoring and analysing the transient line current waveform during the starting period. This is a particularly onerous time for the machine and the inter-relationships between parameters such as current, torque, speed and time are very complex. As a result two parallel paths of …
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An improved electronic ballast for the fluorescent lamps
… the high total harmonic distortion (THO) of the line current, and the poor crest factor ( CF) of the lamp current in this circuit make it difficult to manufacture this circuit into a cost-effective ballast product. This thesis analyzes the problems associated with the "charge pump" electronic …
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Calculation of Unbalanced Magnetic Pull in Cage Induction Machines
… between predicted and measured values of UMP and line current is found to be good. The investigation leads to several new aspects of the damping effects of parallel stator windings and the cage rotor being highlighted.
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Analysis and Comparison of Space Vector Modulation Schemes for Three-Leg and Four-Leg Voltage Source Inverters
… distortion, c) peak-to-peak ripple in the line current and d) the ease of digital implementation. The analysis is performed over the entire range of modulation index and for varying load power factors (leading and lagging) under both balanced and unbalanced load conditions. The analysis …
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Magnetic perturbations due to current structural variations
… of the magnetic perturbations caused by auroral currents has been conducted by rocket-borne magnetometer measurements for years. Since the horizontal auroral currents were usually found to be confined near the visible auroral arcs, as determined by Heppner [1954], Davis [1961], and Davis and …
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Additive manufacturing applications and implementation in aerospace
… to additive manufacturing solutions to stream-line current production processes and open opportunities for on-demand producibility. While many OEMs are drawn to the appeal of the benefits that additive manufacturing brings, they are beginning to understand the difficulties in what it takes to …
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Three phase inverter for induction motor by using pi-repetitive controller with arduino
… eliminates the periodic errors on the output current due to inverter current nonlinearity and load disturbances. The controller is implemented on a gate driver, three phase inverter and filter prototypes which are constructed in laboratory. Open-loop and closed-loop condition are verified by …
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Induction motor fault recognition.
… induction machine parameters such as vibration, line current and leakage flux which alter during machine faults. Initially a survey was conducted to determine which machine failures were of concern to industrial operators. Faults analysed in this thesis include rotor bar faults, unbalanced …
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Digital control of a multi-channel boundary-conduction-mode boost converter for power-factor-correction applications
… cost and having high efficiency for a universal line-voltage input. Single-channel and two-channel BCM boost converters using analog control ICs have been commonly used in industry. However, the use of multi-channel BCM boost converters with more than two-channels has been limited as there are no …
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Average current-mode control and charge control for PWM converters
Two control schemes for PWM converters, average current-mode (ACM) control and charge control, are studied in this dissertation. The small-signal models are derived for continuous-conduction mode PWM converters employing these two controls. Sampled-data modeling is applied to the current loop …
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The analysis of airgap eccentricity in three-phase induction motors using finite elements for a reliable condition monitoring strategy.
… calculated specific frequency components in the line current spectra which are a function of airgap eccentricity. An attempt was also made using classical techniques to predict the magnitude of these components as a function of the airgap eccentricity severity. Agreements between predicted and …
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Design and analysis of a 200 volt, high slew rate, current-limited operational amplifier
… the kV/s range, while having clean, adjustable current limiting and low quiescent current consumption. Several common amplifier topologies are examined, with their merits and drawbacks discussed in the context of the use case. Ultimately, a hybridized approach is taken for an input stage for the …
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Development of a single phase active Power filter for rectifier load
… to regulate the DC bus voltage and hysteresis current controller is employed to generate signal for switching purpose. The process is based on sensing line currents, filter currents and DC side capacitor voltage. The error signal caused by the filter has been computed firstly. Then this error …
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An AC-AC inverter for high frequency power distribution system
… be high frequency ac type and be combined with line current Power Factor Correction that satisfies IEC 1000-3-2 standard. In addition, low power applications require high efficiency, high power density and cost effectiveness. This thesis provides a solution to low power ac-ac inverter for the …
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High-frequency, high-pole count design for improving specific power density of electric machines
… reactance is shown to result in growth in line current and low torque. For permanent magnet machines, however, reduction in magnetizing reactance is shown to not directly affect torque of the machine, thus increase in specific power density is shown. The design of a 1 MW, 13 kW/kg motor is …
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AC/DC power system small-signal impedance measurement for stability analysis
… However, for ac systems, the traditional current-injection techniques are not suitable, especially for the high power systems. The first contribution of this work is the unique process of injecting a line-to-line current between two phases of a three-phase ac system for the purpose of …
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Modeling of Multi-Pulse Transformer/Rectifier Units in Power Distribution Systems
… low total harmonic distortion (THD) of the input line current. This increase in the use of multi-pulse transformer topologies has led to the need to study large systems composed of said units and their interactions within the system. There is also an interest in developing small-signal models so …
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ANALYSIS OF COMPOSITE A-C AND D-C SYSTEMS
… transient stability analysis in which the d-c line current changes and the convertor firing controls were also simulated.
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Current based condition monitoring of electromechanical systems. Model-free drive system current monitoring: faults detection and diagnosis through statistical features extraction and support vector machines classification.
A non-invasive, on-line method for detection of mechanical (rotor, bearings eccentricity) and stator winding faults in a 3-phase induction motors from observation of motor line current supply input. The main aim is to avoid the consequence of unexpected failure of critical equipment which results …
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Experimental investigation of the trigger problem in magnetic reconnection
… is facilitated by an interaction between the x-line current channel and a global mode, which breaks axisymmetry. We model the onset using an empirical Ohm's law and current continuity, which is maintained by ion polarization currents associated with the mode. The model reproduces the exponential …
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