EPE Association: EPE 1985 - 33 - Dialogue Session 3.1: DIALOGUE / POSTER SESSION (III)

EPE 1985 - 33 - Dialogue Session 3.1: DIALOGUE / POSTER SESSION (III)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 33 - Dialogue Session 3.1: DIALOGUE / POSTER SESSION (III)

   [return to parent folder]

   THYRISTOR ADJUSTABLE SPEED WITH HIGH POWER FACTOR OF AC MOTOR
By Xu Kexiang [View]
[Download]

Abstract: This paper presents a principle of thyristor adjustable speed system with high power factor and efficiency of A.C. motor which achievement appraisal of scientific research project was passed on Aug. 10, 1984 in Canton, China. The experimental results of the system with different load and regulating speed are given. Finally, a comparison is made between it and conventional system.

   ANALYSIS OF A TRANSISTOR CONTROLLED STEPPING MOTOR
By M. Crivii; V. Trifa; A. Broscoi [View]
[Download]

Abstract: The Paper deals with an energizing and control circuit for high torque and frequency stepping motors. Description of the drive circuit, deduction of the mathematical model of the ensemble D.C. source-switching circuit-motor, theoretical study of the ensemble by numerical simulation, and also the presentation of experimental results are given. The circuit presented is one of the most efficient for driving large-current stepping motors at high voltages, independently of their R, L parameters.

   A SEPARATELY EXCITED DC MOTOR SUPPLIED FROM A UC CHOPPER SUPPLY
By A. A. El-Sattar; F. Y. Ahmed [View]
[Download]

Abstract: This paper deals with a separately excited dc motor fed from a voltage commutated dc chopper supply. The chopper is of a pulse width modulated nature. It operates with constant frequency which enables easier filter design. This system is preferable because it is simple and gives wide range of speed control. The system operation is represented by a set of linear differential equations. The solution of the system has been obtained using state variable method of analysis. Both continuous and discontinuous modes of operation have been obtained. The solution predicts the performance of the system for both transient and steady-state conditions. Experimental motor voltage and current waveforms for both continuous and discontinuous modes of operation have been recorded. The computed results have been compared with these obtained experimentally.

   ANALYSIS OF SINGLE-PHASE INDUCTION MOTORS CONTROLLED BY AC CHOPPERS USING STATE-SPACE TECHNIQUES
By S. M. Al-Ma Sarawy; I. A. Mohammed; J. H. H. Alwash [View]
[Download]

Abstract: State-Space techniques are used for the Steady-State analysis of a Single-Phase induction motor controlled by symmetrical and asymmetrical ac choppers. Torque, power factor, overall efficiency and distortion factor of the input current are computed for various load conditions. Effect of chopping asymmetry on the performance is discussed. A camparison is made between the performance characteristics of a single-phase induction motor when the stator voltage is controlled using an ac chopper and back to back connected thyristors. Computed results for the waveform of the main winding current is compared with test results.

   OSCILLATORY RELUCTANCE LINEAR DRIVE OF A PLATE LIQUID EXTRACTOR
By O. Roubicek; Z. Pejsek; J. Rozprim; O. Pekarek; J. Prochazka; A. Heyberger [View]
[Download]

Abstract: The development of oscillatory plate liquid extracter controlled by microcomputer proves to be an extraordinary progress in the technology of separation of liquid solutions (liquid extraction technology). Its design and operation possibilities enable substantial development in the application of a drive with asymmetrical oscillatory reluctance linear motor. Its most valuable contribution is excellent two-parameters control af oscillations of the active part of the extracter and its reliable hermetic sealing. The new design of extracter was successfully experimentally verified and its application in practice is being prepared.

   MICROPROCESSOR STARTING OF SLIP RING INDUCTION MOTOR
By M. M. Elmissiry [View]
[Download]

Abstract: This paper presents a controller for the static variation of the starting resistance of slip-ring induction motor according to a prescribed starting algorithm. The controller employs a microprocessor controlled chopper circuit where the mark-space ratio of the chopper can be varied according to a required algorithm. The whole system is a closed loop control system in which the rotor speed determines the value of the starting resistance. Two different starting algorithms have been derived and implemented using the controller. The first is for starting the motor under constant current and the second algorithm is for starting the motor in the minimum possible time. Experimental results are given when the above two starting algorithms are applied to a 5 kW slip-ring induction motor.

   A NOVEL ELECTROMAGNETIC SUSPENSION SYSTEM FOR CONVEYOR-TYPE APPLICATIONS
By J. D. Edwards; B. V. Jayawant; M. A. Preston; J. Willsher [View]
[Download]

Abstract: An electromagnetic suspension system is described, in which a suspended moving object (the runner) is completely passive. The runner comprises three sets of iron pole-pieces separated by non-magnatic spacers to form a hexagonal structure, it is suspended magnetically in a tunnel formed by three iron-cored stators with distributed coils. The airgaps between the runner poles and the stators are held constant by feedback control, and the runner is moved axially by microcomputer control of the currents in the stator coils. Each stator has a 2-phase winding, with the coils grouped in pairs: each pair of coils is supplied from a separate pulsewidth modulated MOSFET power amplifier which uses a novel design for compactness and reliability. The dynamic behaviour of the 2-phase system is described, there is a severe nonlinearity in the control characteristic, which makes a constant runner velocity difficult to achieve, this problem can be largely eliminated by using a 4-phase system.

   ASYMMETRIC FIRING OF THE SWITCHING DEVICES FOR THE FEEDING OF THE THREE-PHASE INDUCTION MOTORS
By V. Isastia; V. Peluso; M. Scarano [View]
[Download]

Abstract: This paper deals with the possible alterations that occur on the power and on the torque of a three phase induction motor fed by switching devices. These alterations happen, in particular way, when asymmetrical switching of the devices themselves takes place. The value of the steady-state quantities are determined, for different conditions of considered asymmetry, by means of a differential iterative formulation, by using the state transition method.

   MODE TRANSITIONS OF A THREE-PHASE INDUCTION MOTOR IN ASYMMETRIC SWITCHED FEEDING
By V. Isastia; V. Peluso; M. Scarano [View]
[Download]

Abstract: The present paper deals with the study about the mode transition as regards the three phase induction motor fed through switching devices in asymmetrical firing conditions. The boundaries of the existence domains of the different modes are deduced by formulating the method of the state transition in finite difference terms.

   ADDITIONAL LOSSES OF A DC MOTOR FED FROM AN ASYMMETRICAL BRIDGE
By R. Saveljic; M. Djurovic [View]
[Download]

Abstract: The additional losses of a DC motor fed from an asymmetrical single phase bridge can be determined by an equivalent resistance which is calculated by the polynomial approximation based on experimental data. It has been shown that very limitted number of experimental data qives very good approximation. The results obtained by this method give better accuracy then any other method known to the authors. The method makes the calculations very simple. It does not depend on the agreement between frequencies of the parameters and frequencies of armature current ripple. The higher accuracy is achieved in the case when frequencies of measured parameters respond to frequencies of main line current ripple.

   THE FIELD-ORIENTATED CONTROL OF THE CYCLOCONVERTER FED DOUBLY FED INDUCTION MACHINE
By J. M. Pacas [View]
[Download]

Abstract: The aim of this paper is to present a new electrical drive consisting of a series connected doubly fed-induction machine fed by a line-commutated cycloconverter and controlled by means of a novel field-orientated control scheme. The series connected doubly fed induction machine runs at twice the synchronous speed of the same machine at the same supply frequency but with short-circuited slip rings. An enlargement of the speed operation range of cycloconverter fed drives is therefore possible using the doubly-fed induction machine as electromechanical energy converter. The principles of the field-orientated control methods for AC-machines applied to the equations of the doubly-fed induction machine yield a control scheme, which enables the calculation of the reference values for the cycloconverter voltages from the reference values for the electromagnetic torque and the magnetization. The presented control system was realized using a 16-bit microcomputer. It was tested on a laboratory drive. Measurements confirm the validity of the theoretical statements.

   DIGITAL SIMULATION OF AN INVERTER INDUCTION MOTOR
By K. Surendran; V. Subrahmanyam [View]
[Download]

Abstract: A digital simulation procedure for the analysis of a voltage source inverter feeding a three phase induction motor is presented. The inverter feeding the motor is the well known McMurray inverter. The model of the motor used in the simulation is based on the machine equations in the phase coordinates. The effect of changes in system parameters is studied. Critical performance criteria like peak value of armature current and peak voltage across the inverter thyristors are obtained. These are very much helpful in the design of inverter and associated circuits. The performance of the inverter motor combination at representative frequencies of 50, 25 and 5 Hz is studied and the results presented.

   CURRENT SOURCE INVERTER-FED INDUCTION MOTOR DRIVE SYSTEM CONTROLLED WITHOUT A SPEED SENSOR
By M. P. Kazmierkowski; H. J. Kopcke [View]
[Download]

Abstract: Presented control system for CSI-drive is based on the idea of field orientated control. In contrast to well known ways of realisation a torque proportional quantity is calculated from stator voltage and current without explicit flux calculation or integration. A speed sensor is not required. The discussion on the theoretical principles of this method and some transients illustrating the performance of the realized drive system are presented.

   DYNAMIC CHARACTERISTICS OF A CURRENT INVERTER INDUCTION MOTOR DRIVE UNDER DIFFERENT CONTROL STRATEGIES
By E. Bassi; S. Bolognani; G. Buja [View]
[Download]

Abstract: A unified approach is presented to the analysis of the dynamic characteristics of three current inverter induction motor (CSIM) drives incorporating the following control strategies: slip, synchronous, and field-oriented. After establishing a generalized model of the CSIM operation, for each drive the control system is identified, the transfer functions are calculated, and merits and limits are illustrated. An overall diagram is also given, which highlights the different control actions accomplished by the three strategies.

   CALCULATION OF CHARACTERISTICS OF THE INVERTER-FED SQUIRREL-CAGE INDUCTION MOTOR
By T. Fujimaki; O. Miyashita [View]
[Download]

Abstract: The inverter-fed squirrel-cage induction motors have recently been widely used in many industrial applications. When the motors are operated from a nonsinusoidal power supply, the motor efficiency falls because of the additional copper and iron losses in the stator and the undue loss due to the skin effect in the rotor bars, which may overheat the motor. Therefore it is necessary to predict the characteristics of the motor controlled by an inverter. The purpose of this paper is to present an equivalent circuit to calculate the characteristics of the squirrel-cage induction motor on the nonsinusoidal voltage such as the output of an inverter. The equivalent circuit is constructed so as to represent the eddy current in the stator core and skin effect in the rotor bars with a distributed parameter circuit model. The procedure of determining the circuit constants is as practical as that of the conventional type T equivalent circuit.

   KRAEMER DRIVE: CHARACTERISTICS, LABORATORY TESTS ON A PROTOTYPE AND DIGITAL TOOLS FOR DESIGNING
By F. Carrea; L. Valfre; A. Boglietti; F. Profumo [View]
[Download]

Abstract: The growing interest in energy saving and the continuous improvement in reliability of high power electronic devices combined with cost reductions led to a notable diffusion of well known Kraemer drive for large wound asynchronous motors (0.5 + 20 MW). Such drives allow slip power recovery in the network and large speed regulation of the motor ( 50 + 100% rated speed). Starting from a short description of the main static drive system schemes with slip power recovery, this paper deals with an adopted methodology for a new approach in the system design of static Kraemer drives. Such procedure allows to meet the required drive specifications and to optimize the final design by means of a technical analysis among the available industrial schemes. A digital program has been developed in order to support the preliminary design of the overall power components of a given Kraemer drive scheme and to analyze the steady state behaviour with particular reference to the drive efficiency and to the harmonic current contents. Labaratory investigations have been carried out both for testing the industrial control performances over the complete speed control range and for reproducing the real drive behaviour under critical conditions. A further step of the procedure is the dynamic analysis of the drive behaviour by means of a detailed digital model for both power and control system. Such model has been implemented by means of the ElectroMagnetic Transient Program (EMTP) package of Bonneville Power Administration (BPA). From the accurate analysis of normal and abnormal operating conditions for different configurations the final scheme can be chosen for better fitting the required performance for each given application. The obtained results for some steady state conditions analysis are presented.

   OPTIMIZATION OF ELECTRIC DRIVING SYSTEM OPERATING UNDER RANDOM DISTURBANCE LOAD CONDITIONS
By K. Jaracz [View]
[Download]

Abstract: In the article the autor present the problem of determining the optimal structure of the electric driving system operating under real load conditions with disturbances. The results of measurements and calculations of probabilistic characteristics of these disturbances appearing at the real operating conditions of the drive are also discussed. Basing on the constructed stochastic model of an electric drive, the two methods of improvement of dynamics of the driving system are shown. The first of these methods is based on the choice of parameters of regulators, the second one is based on the choice of optimal regulator structure, which is based on the scanning principle. The results are illustrated with the simulation experiments.

   ON THE NEW CONCEPT MMD ELECTRICAL MACHINES WITH INTEGRAL MACROELECTRONIC COMMUTATORS - DEVELOPMENT FOR THE FUTURE
By B. T. Fijalkowski [View]
[Download]

Abstract: About five years ago the author started R & D work on integral static macro-electronic integrated-matrixer commutators for use in MMD electrical machine VAD (Very Advanced Drive) and VAP (Very Advanced Propulsion) systems. Today, developments have reached the stage where the third generation of integral static macro-electronic integrated-matrixer commutators, by the author called integral macro-commutators is being introduced, where the power rating may be increased forty times and inherent losses have been halved. This paper gives the background to modern newly designed energy-saving AC and/or DC macro-commutator-based machines. An overview is presented of the state of the art in this area. A number of conceived AC and/or DC macro-commutator-based machines are discussed. Special emphasis is made on development trends and future AC and/or DCmacro-commutator-based machine concepts that will soon become possible thanks to the rapid developments currently taking place in the macro- and micro-electronics. The torque and speed control of AC and/or DC macro-commutator-based dynamotors using integral macro-commutators gives large benefits for many types of duty, particularly in difficult and hazardous environments. This design of the AC and/or DC macro-commutator-based dynamotors and industrial VAD or traction VAP systems are described and some application examples are presented.

EPE 1985 - 33 - Dialogue Session 3.1: DIALOGUE / POSTER SESSION (III)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 33 - Dialogue Session 3.1: DIALOGUE / POSTER SESSION (III)
	[return to parent folder]

	THYRISTOR ADJUSTABLE SPEED WITH HIGH POWER FACTOR OF AC MOTOR By Xu Kexiang	[View] [Download]
Abstract: This paper presents a principle of thyristor adjustable speed system with high power factor and efficiency of A.C. motor which achievement appraisal of scientific research project was passed on Aug. 10, 1984 in Canton, China. The experimental results of the system with different load and regulating speed are given. Finally, a comparison is made between it and conventional system.

	ANALYSIS OF A TRANSISTOR CONTROLLED STEPPING MOTOR By M. Crivii; V. Trifa; A. Broscoi	[View] [Download]
Abstract: The Paper deals with an energizing and control circuit for high torque and frequency stepping motors. Description of the drive circuit, deduction of the mathematical model of the ensemble D.C. source-switching circuit-motor, theoretical study of the ensemble by numerical simulation, and also the presentation of experimental results are given. The circuit presented is one of the most efficient for driving large-current stepping motors at high voltages, independently of their R, L parameters.

	A SEPARATELY EXCITED DC MOTOR SUPPLIED FROM A UC CHOPPER SUPPLY By A. A. El-Sattar; F. Y. Ahmed	[View] [Download]
Abstract: This paper deals with a separately excited dc motor fed from a voltage commutated dc chopper supply. The chopper is of a pulse width modulated nature. It operates with constant frequency which enables easier filter design. This system is preferable because it is simple and gives wide range of speed control. The system operation is represented by a set of linear differential equations. The solution of the system has been obtained using state variable method of analysis. Both continuous and discontinuous modes of operation have been obtained. The solution predicts the performance of the system for both transient and steady-state conditions. Experimental motor voltage and current waveforms for both continuous and discontinuous modes of operation have been recorded. The computed results have been compared with these obtained experimentally.

	ANALYSIS OF SINGLE-PHASE INDUCTION MOTORS CONTROLLED BY AC CHOPPERS USING STATE-SPACE TECHNIQUES By S. M. Al-Ma Sarawy; I. A. Mohammed; J. H. H. Alwash	[View] [Download]
Abstract: State-Space techniques are used for the Steady-State analysis of a Single-Phase induction motor controlled by symmetrical and asymmetrical ac choppers. Torque, power factor, overall efficiency and distortion factor of the input current are computed for various load conditions. Effect of chopping asymmetry on the performance is discussed. A camparison is made between the performance characteristics of a single-phase induction motor when the stator voltage is controlled using an ac chopper and back to back connected thyristors. Computed results for the waveform of the main winding current is compared with test results.

	OSCILLATORY RELUCTANCE LINEAR DRIVE OF A PLATE LIQUID EXTRACTOR By O. Roubicek; Z. Pejsek; J. Rozprim; O. Pekarek; J. Prochazka; A. Heyberger	[View] [Download]
Abstract: The development of oscillatory plate liquid extracter controlled by microcomputer proves to be an extraordinary progress in the technology of separation of liquid solutions (liquid extraction technology). Its design and operation possibilities enable substantial development in the application of a drive with asymmetrical oscillatory reluctance linear motor. Its most valuable contribution is excellent two-parameters control af oscillations of the active part of the extracter and its reliable hermetic sealing. The new design of extracter was successfully experimentally verified and its application in practice is being prepared.

	MICROPROCESSOR STARTING OF SLIP RING INDUCTION MOTOR By M. M. Elmissiry	[View] [Download]
Abstract: This paper presents a controller for the static variation of the starting resistance of slip-ring induction motor according to a prescribed starting algorithm. The controller employs a microprocessor controlled chopper circuit where the mark-space ratio of the chopper can be varied according to a required algorithm. The whole system is a closed loop control system in which the rotor speed determines the value of the starting resistance. Two different starting algorithms have been derived and implemented using the controller. The first is for starting the motor under constant current and the second algorithm is for starting the motor in the minimum possible time. Experimental results are given when the above two starting algorithms are applied to a 5 kW slip-ring induction motor.

	A NOVEL ELECTROMAGNETIC SUSPENSION SYSTEM FOR CONVEYOR-TYPE APPLICATIONS By J. D. Edwards; B. V. Jayawant; M. A. Preston; J. Willsher	[View] [Download]
Abstract: An electromagnetic suspension system is described, in which a suspended moving object (the runner) is completely passive. The runner comprises three sets of iron pole-pieces separated by non-magnatic spacers to form a hexagonal structure, it is suspended magnetically in a tunnel formed by three iron-cored stators with distributed coils. The airgaps between the runner poles and the stators are held constant by feedback control, and the runner is moved axially by microcomputer control of the currents in the stator coils. Each stator has a 2-phase winding, with the coils grouped in pairs: each pair of coils is supplied from a separate pulsewidth modulated MOSFET power amplifier which uses a novel design for compactness and reliability. The dynamic behaviour of the 2-phase system is described, there is a severe nonlinearity in the control characteristic, which makes a constant runner velocity difficult to achieve, this problem can be largely eliminated by using a 4-phase system.

	ASYMMETRIC FIRING OF THE SWITCHING DEVICES FOR THE FEEDING OF THE THREE-PHASE INDUCTION MOTORS By V. Isastia; V. Peluso; M. Scarano	[View] [Download]
Abstract: This paper deals with the possible alterations that occur on the power and on the torque of a three phase induction motor fed by switching devices. These alterations happen, in particular way, when asymmetrical switching of the devices themselves takes place. The value of the steady-state quantities are determined, for different conditions of considered asymmetry, by means of a differential iterative formulation, by using the state transition method.

	MODE TRANSITIONS OF A THREE-PHASE INDUCTION MOTOR IN ASYMMETRIC SWITCHED FEEDING By V. Isastia; V. Peluso; M. Scarano	[View] [Download]
Abstract: The present paper deals with the study about the mode transition as regards the three phase induction motor fed through switching devices in asymmetrical firing conditions. The boundaries of the existence domains of the different modes are deduced by formulating the method of the state transition in finite difference terms.

	ADDITIONAL LOSSES OF A DC MOTOR FED FROM AN ASYMMETRICAL BRIDGE By R. Saveljic; M. Djurovic	[View] [Download]
Abstract: The additional losses of a DC motor fed from an asymmetrical single phase bridge can be determined by an equivalent resistance which is calculated by the polynomial approximation based on experimental data. It has been shown that very limitted number of experimental data qives very good approximation. The results obtained by this method give better accuracy then any other method known to the authors. The method makes the calculations very simple. It does not depend on the agreement between frequencies of the parameters and frequencies of armature current ripple. The higher accuracy is achieved in the case when frequencies of measured parameters respond to frequencies of main line current ripple.

	THE FIELD-ORIENTATED CONTROL OF THE CYCLOCONVERTER FED DOUBLY FED INDUCTION MACHINE By J. M. Pacas	[View] [Download]
Abstract: The aim of this paper is to present a new electrical drive consisting of a series connected doubly fed-induction machine fed by a line-commutated cycloconverter and controlled by means of a novel field-orientated control scheme. The series connected doubly fed induction machine runs at twice the synchronous speed of the same machine at the same supply frequency but with short-circuited slip rings. An enlargement of the speed operation range of cycloconverter fed drives is therefore possible using the doubly-fed induction machine as electromechanical energy converter. The principles of the field-orientated control methods for AC-machines applied to the equations of the doubly-fed induction machine yield a control scheme, which enables the calculation of the reference values for the cycloconverter voltages from the reference values for the electromagnetic torque and the magnetization. The presented control system was realized using a 16-bit microcomputer. It was tested on a laboratory drive. Measurements confirm the validity of the theoretical statements.

	DIGITAL SIMULATION OF AN INVERTER INDUCTION MOTOR By K. Surendran; V. Subrahmanyam	[View] [Download]
Abstract: A digital simulation procedure for the analysis of a voltage source inverter feeding a three phase induction motor is presented. The inverter feeding the motor is the well known McMurray inverter. The model of the motor used in the simulation is based on the machine equations in the phase coordinates. The effect of changes in system parameters is studied. Critical performance criteria like peak value of armature current and peak voltage across the inverter thyristors are obtained. These are very much helpful in the design of inverter and associated circuits. The performance of the inverter motor combination at representative frequencies of 50, 25 and 5 Hz is studied and the results presented.

	CURRENT SOURCE INVERTER-FED INDUCTION MOTOR DRIVE SYSTEM CONTROLLED WITHOUT A SPEED SENSOR By M. P. Kazmierkowski; H. J. Kopcke	[View] [Download]
Abstract: Presented control system for CSI-drive is based on the idea of field orientated control. In contrast to well known ways of realisation a torque proportional quantity is calculated from stator voltage and current without explicit flux calculation or integration. A speed sensor is not required. The discussion on the theoretical principles of this method and some transients illustrating the performance of the realized drive system are presented.

	DYNAMIC CHARACTERISTICS OF A CURRENT INVERTER INDUCTION MOTOR DRIVE UNDER DIFFERENT CONTROL STRATEGIES By E. Bassi; S. Bolognani; G. Buja	[View] [Download]
Abstract: A unified approach is presented to the analysis of the dynamic characteristics of three current inverter induction motor (CSIM) drives incorporating the following control strategies: slip, synchronous, and field-oriented. After establishing a generalized model of the CSIM operation, for each drive the control system is identified, the transfer functions are calculated, and merits and limits are illustrated. An overall diagram is also given, which highlights the different control actions accomplished by the three strategies.

	CALCULATION OF CHARACTERISTICS OF THE INVERTER-FED SQUIRREL-CAGE INDUCTION MOTOR By T. Fujimaki; O. Miyashita	[View] [Download]
Abstract: The inverter-fed squirrel-cage induction motors have recently been widely used in many industrial applications. When the motors are operated from a nonsinusoidal power supply, the motor efficiency falls because of the additional copper and iron losses in the stator and the undue loss due to the skin effect in the rotor bars, which may overheat the motor. Therefore it is necessary to predict the characteristics of the motor controlled by an inverter. The purpose of this paper is to present an equivalent circuit to calculate the characteristics of the squirrel-cage induction motor on the nonsinusoidal voltage such as the output of an inverter. The equivalent circuit is constructed so as to represent the eddy current in the stator core and skin effect in the rotor bars with a distributed parameter circuit model. The procedure of determining the circuit constants is as practical as that of the conventional type T equivalent circuit.

	KRAEMER DRIVE: CHARACTERISTICS, LABORATORY TESTS ON A PROTOTYPE AND DIGITAL TOOLS FOR DESIGNING By F. Carrea; L. Valfre; A. Boglietti; F. Profumo	[View] [Download]
Abstract: The growing interest in energy saving and the continuous improvement in reliability of high power electronic devices combined with cost reductions led to a notable diffusion of well known Kraemer drive for large wound asynchronous motors (0.5 + 20 MW). Such drives allow slip power recovery in the network and large speed regulation of the motor ( 50 + 100% rated speed). Starting from a short description of the main static drive system schemes with slip power recovery, this paper deals with an adopted methodology for a new approach in the system design of static Kraemer drives. Such procedure allows to meet the required drive specifications and to optimize the final design by means of a technical analysis among the available industrial schemes. A digital program has been developed in order to support the preliminary design of the overall power components of a given Kraemer drive scheme and to analyze the steady state behaviour with particular reference to the drive efficiency and to the harmonic current contents. Labaratory investigations have been carried out both for testing the industrial control performances over the complete speed control range and for reproducing the real drive behaviour under critical conditions. A further step of the procedure is the dynamic analysis of the drive behaviour by means of a detailed digital model for both power and control system. Such model has been implemented by means of the ElectroMagnetic Transient Program (EMTP) package of Bonneville Power Administration (BPA). From the accurate analysis of normal and abnormal operating conditions for different configurations the final scheme can be chosen for better fitting the required performance for each given application. The obtained results for some steady state conditions analysis are presented.

	OPTIMIZATION OF ELECTRIC DRIVING SYSTEM OPERATING UNDER RANDOM DISTURBANCE LOAD CONDITIONS By K. Jaracz	[View] [Download]
Abstract: In the article the autor present the problem of determining the optimal structure of the electric driving system operating under real load conditions with disturbances. The results of measurements and calculations of probabilistic characteristics of these disturbances appearing at the real operating conditions of the drive are also discussed. Basing on the constructed stochastic model of an electric drive, the two methods of improvement of dynamics of the driving system are shown. The first of these methods is based on the choice of parameters of regulators, the second one is based on the choice of optimal regulator structure, which is based on the scanning principle. The results are illustrated with the simulation experiments.

	ON THE NEW CONCEPT MMD ELECTRICAL MACHINES WITH INTEGRAL MACROELECTRONIC COMMUTATORS - DEVELOPMENT FOR THE FUTURE By B. T. Fijalkowski	[View] [Download]
Abstract: About five years ago the author started R & D work on integral static macro-electronic integrated-matrixer commutators for use in MMD electrical machine VAD (Very Advanced Drive) and VAP (Very Advanced Propulsion) systems. Today, developments have reached the stage where the third generation of integral static macro-electronic integrated-matrixer commutators, by the author called integral macro-commutators is being introduced, where the power rating may be increased forty times and inherent losses have been halved. This paper gives the background to modern newly designed energy-saving AC and/or DC macro-commutator-based machines. An overview is presented of the state of the art in this area. A number of conceived AC and/or DC macro-commutator-based machines are discussed. Special emphasis is made on development trends and future AC and/or DCmacro-commutator-based machine concepts that will soon become possible thanks to the rapid developments currently taking place in the macro- and micro-electronics. The torque and speed control of AC and/or DC macro-commutator-based dynamotors using integral macro-commutators gives large benefits for many types of duty, particularly in difficult and hazardous environments. This design of the AC and/or DC macro-commutator-based dynamotors and industrial VAD or traction VAP systems are described and some application examples are presented.