K. Debebe

Expert systems for fault diagnosis of VSI fed AC drives

The use of a rule-based expert system for fault diagnosis of a voltage source inverter (VSI) feeding an induction motor are presented. Interactive session between the user and the expert system is employed to determine the faulty device(s) of the VSI fed drive. Based on the response of the operator, the functional and connectivity information coded in the knowledge base of the expert system diagnoses a fault and corrective measures and advice are given. This could result in an increase in the system availability, reliability, safety, and a reduction in maintenance cost and down time.<<ETX>>

A learning aid for power electronics with knowledge based components

In this paper we have presented a self-study expert system based power electronics instruction aid for selection and analysis of suitable power electronic converter configurations. Converter input output specifications, analysis, and converter design methodologies are interactively pursued with extensive graphical aid to guide the user (student, engineers, etc.) in the study process. Furthermore, transient, steady-state, and harmonic analysis are possible with an integrated simulator within the instruction module. A fault diagnosis expert system based module for converter-fed motor-drives, which can be chained with the expert learning aid, has also been developed. This is in the process of development to diagnose faults on all converters available in the package. >

Diagnosis and monitoring for AC drives

An expert system-based fault detection, diagnosis, and monitoring for a voltage source inverter (VSI) fed AC motor drive called EXDIMPED (expert system for diagnosis and monitoring of power electronic drives) is presented. A unique integration of symptom and topology based reasoning has been employed to diagnose a fault. A method of expert system-based monitoring is also presented. The technique of diagnosis used in the present study could be applied to any drive system with minor modifications.<<ETX>>

User-friendly dedicated power electronic converter simulator

A user-friendly power electronic simulator for the design and analysis of power electronic circuits is presented. A graphic input interface module called ATOSECG has been developed for the dedicated power electronic converter system simulator ATOSEC5. ATOSECG has tremendously facilitated the interaction of the user with the simulator. Examples of application of the ATOSEC5 simulator for the analysis of a complex multiconverter system are given. >

Expert system learning aid for power electronics

The authors present a self study expert system based power electronics instruction aid for the selection and analysis of suitable power electronic converter configurations. Converter input output specifications, analysis, and converter design methodologies are interactively pursued with an extensive graphical aid to guide the user (student, engineers, etc.) in the study process. Furthermore, transient, steady-state, and harmonic analysis are possible with an integrated simulator within the instruction module. A fault diagnosis expert system based module for a converter-fed motor drive, which can be chained with the expert learning aid, has also been developed. This is in the process of development to diagnose faults on all power converters available in the package.<<ETX>>

SEMAS: A new simulation module for AC drive systems

The paper presents an adaptation of the general-purpose SIMNON software for the study of alternating-current drives. With the objective of designing and dimensioning converter-AC machine-regulator systems, a simulation module named SEMAS is constructed in modular form using SIMNON. This software package shows great capabilities in terms of computing power, optimization, robustness of the algorithms and graphical interaction. Asynchronous and synchronous machine models implemented in SEMAS are presented. The different methods for modelling static converters and switches, with the particularities of each, are also presented. The results show evidence of a good agreement between simulations and experiments.

Global simulation of multiple power electronic converter system using a novel iterative method

The present work contributes to the development of a novel method of modeling a power electronic converter in terms of nonlinear current sources, and a novel method of solution for multiconverter systems using an iterative method. The algorithms that are developed based on this methodology have been incorporated in the modified version of the ATOSEC5 simulator called ATOSECM. The authors give an example with single-phase two line-commutated converters to illustrate the methodology. Also presented is a comparison between global simulation (ATOSEC5) and the method of simulation developed here (ATOSECM) for two six-pulse converters supplied by the mains.<<ETX>>

Modelling and simulation of point-on-line switching of VSI fed induction motor

A method of mathematical solution to simulate point-on-line switching of an induction motor after a brief moment of disconnection is presented. The three phases supplying the motor are simultaneously disconnected and are reconnected back to the motor simultaneously or in some sequence. The effect of such operation on the transient air-gap torque is analyzed.<<ETX>>

A new iterative method for the global simulation of power electronic multi-converter systems

Power electronic converters generate harmonic currents that can disturb the network. To study the perturbations on the power line, it is necessary to perform a functional analysis via a global simulation. However, when the plant contains several static power converters feeding direct-current loads, global simulation becomes difficult, even impossible, because of the limitations of the software or the microcomputer used. There are no simulation tools that allow the quantitative evaluation of harmonic voltages and currents generated by a multistatic converter system. To fulfil this goal, the authors propose a new iterative analysis method for such systems and a new model for electronic power converters in terms of nonlinear current sources. This methodology has been included in a modified version of the ATOSECS software, renamed ATOSECM. The methodology is illustrated with an example of the use of ATOSECM on a personal computer for the study of two single-phase power converters connected to the same power line. A comparative analysis between global simulation (ATOSECS) and the new method of simulation (ATOSECM) is also presented for the case of two three-phase full-wave thyristor converters, with different firing angles and loads.

A novel DC-DC resonant converter: improving quasi-resonant converter characteristics

A comprehensive analysis of a resonant switching cell based converter that combines the advantages of those of quasi-resonant (QR) and a bidirectional source (BS) based converter is presented. This converter has the following characteristics: (1) filtering is achieved by a capacitor and a very small inductance, (2) the range of load variation is very high under soft commutated conditions, and (3) there are limited voltage stresses on the main switch.<<ETX>>