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This paper presents an experimental testing of a wavelet packet transform (WPT)-based technique for protecting and controlling three-phase voltage-source (VS) pulse-width modulated (PWM) inverters under extreme load conditions. The proposed technique is based on a two-level multiresolution analysis (MRA) applied on output currents of a 3 [phi] VS PWM inverter. The MRA aims to extract certain signatures, which are the second level highest frequency subband coefficients. These coefficients take a nonzero value for any signal that is short-duration, nonperiodic and nonstationary with impulse-super imposed high frequencies. Such a signal perfectly matches a current arising from any typical fault occurring in either the inverter legs or on the load side. The proposed technique is realized using a C-code hosted and executed by a dSPACE ds1102 controller board. The tested inverter supplies loads that include a 3 [phi] Y-connected R - L load, a 3 [phi] squirrel-cage induction motor and a 3 [phi] synchronous reluctance motor. The extreme load conditions include inverter open-leg, motor starting currents and different faults in motor stator windings. The experimental test results show accurate, fast, and effective response to all disturbances including fault currents by the proposed WPT-based technique. Index Terms--Daubechies (db4), motor protection, multiresolution analysis (MRA), wavelet packet transform (WPT), 3 [phi] voltage-source pulse-width modulated (VS PWM) inverters.

Polyally diglycol carbonate 'CR-39' is widely used as etched track type particle detector. Doppler broadening positron annihilation (DBPAT) provides direct information about core and valance electrons in (CR-39) due to [...]

This paper presents real-time implementation and testing of a wavelet-packet-transform-based algorithm for power transformer protection. The proposed algorithm is implemented using a DS1102 digital signal processor board and tested on two different three-phase power transformers. Different magnetizing inrush, normal (through-fault) and internal fault currents are investigated for different loading conditions. The results show a complete independence from both the transformer parameters and current transformer saturation. In addition, the proposed algorithm has reduced computational burden, high speed, high accuracy, small required memory, and high reliability. In all cases of the investigated internal faults, the proposed algorithm is capable of identifying the fault and generating a trip signal in less than a quarter cycle based on a 60-Hz system. Index Terms--Current transformer (CT) saturation and Daubechies wavelet (db4), current transformers (CTs), differential current, differential protection, internal faults, magnetizing inrush current, power transformer, wavelet transforms.

This paper presents a novel speed control scheme using a genetic-based fuzzy logic controller (GFLC) for an interior permanent-magnet synchronous motor (IPMSM) drive. The proposed GFLC is developed to have less computational burden, which makes it suitable for real-time implementation. The parameters for the GFLC are tuned by genetic algorithm (GA). The complete drive incorporating the GFLC is successfully implemented in real-time using a digital signal processor board DS 1102 for a laboratory 1-hp interior permanent magnet motor. The efficacy of the proposed GFLC-based IPMSM drive is verified by simulation as well as experimental results at various operating conditions. A performance comparison with a conventional proportional--integral controller is also provided to show the superiority of the proposed controller. The proposed GFLC is found to be robust for high-performance industrial drive applications. Index Terms--Digital signal processor (DSP), fuzzy logic, genetic algorithm (GA), interior permanent-magnet (IPM) motor, real-time implementation, vector control.

This paper presents a novel approach of speed control for a permanent magnet synchronous motor (PMSM) using on-line self tuning artificial neural network (ANN). Based on motor dynamics and non-linear load characteristics, an ANN speed controller is developed and integrated with the vector control scheme of the PMSM drive. The combined use of off-line and on-line weights and biases adjustments offers a unique feature of on-line system identification and precise speed control of a high performance PMSM drive. The complete drive system is implemented in real time using a digital signal processor controller board-DS1102 on a laboratory 1 hp PMSM. using the experimental setup, the performances of the proposed drive system are evaluated under various operating conditions. The test results validate the efficacy of the ANN for precise speed control of the PMSM drive. Furthermore, the use of ANN makes the drive system robust, accurate and insensitive to parameter variations. Keywords - Artificial Neural Network, Permanent Magnet Synchronous Motor, On-line System Identification, Hysteresis Current Controller, Speed Control

This work presents a novel technique to distinguish between magnetizing inrush and internal fault currents of a power transformer. The proposed differential algorithm is based on artificial neural network (ANN) and unlike the existing relaying techniques, this method is independent of the harmonic contents of the differential current. A novel neural network is designed and trained using back-propagation algorithm with experimental data. After training the network, simulation and on-line tests are carried out to evaluate the performance of the ANN based algorithm under different fault and energization conditions. Both simulation and experimental results are quite satisfactory.

A stand-alone digital relay has been designed and implemented. The relay can be modified easily to accommodate the protection of different types of transformers by changing the software only. Presented in this paper are the real-time experimental results of five selected algorithms implemented using this digital relay. These algorithms are: discrete Fourier transform, Walsh function, rectangular transform, finite impulse response and least-square. based on the experimental results, the discrete Fourier transform (DFT) algorithm is found to be the best algorithm in terms of accuracy and speed for digital implementation of the differential relay for power transformers. Keywords: Digital relay, power transformer, differential protection, testing algorithms.

Hysteresis current controllers having fixed bands are used in inverters of high-performance ac drives. The switching frequency of such controllers varies over the fundamental period of the modulating signal. The maximum switching frequency (MSF) of these controllers is high. To limit the MSF within the limit of inverter switches, fixed carrier lockouts are usually incorporated. The incorporation of carrier lockouts causes current distortion, and load currents do not confine within the predetermined band. In this paper, two new controllers are proposed. One is a mixed-mode controller of sinusoidal band added to a fixed band, and the other is an equidistant-band current controller. Performances of the proposed controllers are compared with the performances of the conventional fixed-band and sinusoidal-band controllers. Index Terms - AC drives, hysteresis controllers, hysteresis current controllers, PWM inverters, PWM techniques.

A method to analyze the steady-state performance of a stand-alone permanent magnet synchronous generator driven by a diesel engine is presented. The proposed method is based on the equivalent d-q circuits and phasor diagram of such a generator in steady-state condition. A fixed capacitor-thyristor controlled reactor scheme is used to regulate the generator terminal voltage by controlling the thyristor ignition angle. Furthermore the overall system dynamics are modelled in terms of state variables and control inputs. Based on a reduced order linearized model, digital optimal state and output feedback controllers are designed by minimising a quadratic performance index using the dynamic programming technique. The objective of the controller is to maintain the load voltage and frequency constant under varying load conditions. The controller's effectiveness is assessed by examining the closed-loop system response to sudden load changes. Keywords: Permanent magnet synchronous generators, optimal control, static VAR compensator.

Several approaches have been developed for a better simulation of the starting and synchronous performances of an interior-type permanent magnet synchronous motor. The major feature in this study is to combine the finite element analysis with lumped parameter model to provide desirable engineering information but at minimum computational effort. To this end, two co-ordinated stages are involved. One is to develop a unified lumped parameter model applicable for both the steady-state and dynamic analysis. The other stage is to extract individual lumped parameters from the finite element solutions. Based on the derived finite element formulae suitable for both the current source and voltage source supplies, the non-linearity and skin effects are appropriately taken into account.

Several types of ac bearingless motors are proposed. These bearingless motors have conventional four-pole stator windings and additional two- pole windings, whose currents produce radial forces acting on the rotor. General expressions of the machine inductances and radial forces are derived for the cylindrical rotor and salient-pole motors. No-load characteristics of laboratory squirrel-cage induction and reluctance-type synchronous bearingless motors are provided. The test motors were successfully driven by the control circuits.

In this paper, an on-line adaptive loss minimization controller (ALMC) for interior permanent magnet motor drives is introduced after the minimum loss operation of these motors is analyzed. The ALMC provides a novel pattern of change in d-axis stator current to achieve a minimum drive input power at any operating condition. The operation of the ALMC results in a smooth and fast loss minimization, thus overcoming the major drawbacks of existing on-line loss minimization control approaches. The proposed ALMC provides more energy savings in comparison with other methods and extends the application of loss minimization control to a class of motor drives requiring efficient and smooth operation in the face of frequent changes in the operating point. The design and DSP implementation of the ALMC applied to an experimental 1 hp rare-earth IPM motor drive are presented. Several experimental results are given to prove the validity of the ALMC. Keywords: Loss minimization control, Efficiency optimization, Permanent magnet motors, On-line control, Adaptive controller.

For most surface mounted permanent magnet synchronous motors, the electrical time constant is relatively small due to its large air gap. This has been exploited recently with small parameter perturbation techniques to develop observers for the position and speed using measurements of currents. In this paper, a singular perturbation algorithm is experimentally evaluated for both current commutation and closed loop speed control of a permanent magnet synchronous motor drive. An improved algorithm is then proposed and related implementation issues are presented. Keywords: sensorless control, observer, singular perturbation, speed control, PMSM drive

The terms used and the values given for the stator inductance Ls, rotor inductance Lr and for the mutual inductance M have not been properly defined. Their listed values are 0.0388 H, 0.0354 H and 0.0354 H respectively. The stator inductance Ls refers to the stator self-inductance Ls and is the sum of the stator leakage inductance Lls and the magnetizing inductance Lms. The rotor inductance Lr refers to the rotor self-inductance Lr and is the sum of the rotor leakage inductance Llr and the magnetizing inductance Lms.