EPE Association: EPE 1995 - 27 - Dialogue Session DS1c: Adjustable Speed Drives

EPE 1995 - 27 - Dialogue Session DS1c: Adjustable Speed Drives
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 27 - Dialogue Session DS1c: Adjustable Speed Drives

   [return to parent folder]

   TWO PHASE SWITCHED RELUCTANCE DRIVE WITH NEW POWER ELECTRONIC CONVERTER FOR LOW COST APPLICATIONS
By M. Barnes; C. Pollock [View]
[Download]

Abstract: The two phase switched reluctance motor requires fewer power electronic components and is easier to construct than its three and four phase equivalents. This paper presents experimental results of a two phase, 1 kW, switched reluctance drive, with high efficiency and a power to weight ratio considerably better than many commercially available alternatives. It is therefore suitable for high volume, low power applications, for which it is cheaper than conventional three and four phase switched reluctance drives. Central to the low cost of the drive, is the use of a novel two phase power electronic converter, which offers cost effective utilisation of power electronic components.

   ROTOR TIME CONSTANT COMPENSATION OF AN INDUCTION MOTOR IN INDIRECT VECTOR CONTROLLED DRIVES
By A. A. Ganji; P. Lataire [View]
[Download]

Abstract: In order to obtain high performance indirect vector control, an on-line rotor time constant (Tr) identification/compensation method has to be included in the drive strategy. In this paper two Tr tracking algorithms, which use the misalignment of the rotor flux vector as an error caused by incorrect rotor time constant are presented. These techniques were evaluated on a commercially available converter.

   ON LINE TUNING OF ROTOR FLUX OBSERVERS FOR FIELD ORIENTED DRIVES USING IMPROVED STATOR BASED FLUX ESTIMATOR FOR LOW SPEEDS
By E.K.K. Sng; A.C. Liew [View]
[Download]

Abstract: The paper describes a model-reference adaptive system (MRAS) used for tuning the rotor time constant or motor speed of an induction motor at low speeds. Tuning of stator parameters using high frequency signals also take place simultaneously to enable the state used by the MRAS to be accurate even at low speeds. Stability and dynamics ofMRAS are presented and verified experimentally on an induction motor at zero speed. Observer of rotor flux based on tUned rotor speed is shown to preserve field orientation at low speeds.

   IGBT DRIVE FOR CONTAINER STACKING CRANES WITH BIDIRECTIONAL SUPPLY
By W.A.G. De Jager; G.H. Tubbing [View]
[Download]

Abstract: This paper deals with an asynchronous variable speed drive developed by Holec Ridderkerk for crane applications. This drive, based on IGBT technology, will be used on a 3 kV / 50 Hz mains supply. Behind a line transformer, the first stage in the power conversion is a controlled 3 phase bridge which feeds a dc-link. The second stage of the drive is a motor inverter. Control of the line-side converter is performed with hysteresis control, while the motor converter is controlled with digital vector control.

   INTELLIGENT MODELS FOR ELECTROMECHANICAL SYSTEMS
By P.J. Costa Branco; J.A. Dente [View]
[Download]

Abstract: This paper proposes apply fuzzy learning techniques for modeling electromechanical systems, incorporating learning capabilities into the control system to adjust itself to the different operating conditions. Compensation of non - linear terms affecting system dynamics and implementation of "intelligent" systems with self-learning capabilities are the main applications for this new association. Three fuzzy algorithms are presented, learning from examples the rules expressing system behavior regardless of having analytical dependency or not. To investigate the association between electromechanical systems and fuzzy modeling, an experimental system composed by an electro-hydraulic position system is used. The performance of the algorithms will be compared and studied for different cases like systems modeling in a direct and indirect way, the number of need examples to build a reasonable model, the different learning capabilities of each algorithm and their use of the accessible information.

   PARAMETERS AND VOLT-AMPERE RATINGS OF A SYNCHRONOUS MOTOR DRIVE FOR FLUX-WEAKENING APPLICATIONS
By N. Bianchi; S. Bolognani [View]
[Download]

Abstract: This paper deals with the characterisation of the motor parameters as well as of the inverter power ratings of a synchronous motor drive able to cover a desired flux-weakening operation range. The motor drive selection data are reported, in" normalised values, in several figures, by which one can derive the more suitable synchronous motor (defined by its d-q axis inductances and flux linkage) and the related inverter volt-ampere ratings.

   INVESTIGATIONS ON A HIGH-SPEED SWITCHED RELUCTANCE DRIVE INCORPORATING AMORPHOUS IRON
By K. Backhaus; L. Link; J. Reinert [View]
[Download]

Abstract: High-speed direct drive applications combine outstanding demands on rugged rotor design and high efficiency. A novel solution might be realized by using a switched reluctance motor with rotor laminations made from amorphous iron. This paper comprises a switched reluctance motor and controller design as well as examinations of overall performance of the drive system.

   VOLTAGE PEAKS OF LOW VOLTAGE INDUCTION MOTORS DUE TO PWM INVERTER SUPPLY
By B. Kawkabani; J.J. Simond; F. Kehtari [View]
[Download]

Abstract: In industrial variable speed drives, the supply of low voltage induction motors by IGBT-PWM inverters through screened cables may cause dangerous over-voltage surges at the motor terminals. These voltage peaks of about twice the dc link voltage, with a short rise time of about 200 nsec, increase the armature insulation stress and may damage the motor insulation. The present study provides a theoretical approach to this matter and is completed by tests performed on two 3 and 7.5 kW drives, with different cable lengths. Its target is to define the properties of these voltage peaks, their dependency on the installation parameters, and to present two measures to reduce the voltage gradient duldt or the peak voltages at the motor terminals in order to raise motor lifetime of such a.c motors.

   ELASTIC FUZZY CONTROLLER AND SLIDING MODE POWER INVERTER FOR ELECTROMECHANICAL POSITIONERS
By J.C. Quadrado; J.F. Silva [View]
[Download]

Abstract: The computation algorithm, some implementation details, the design of sliding mode controlled short circuit proof power inverter, and the experimental performances of an elastic fuzzy controller for electromechanical. positioners are presented. Simulation and laboratory results are compared and attest the expected features of the controller like steady state error elimination, robustness and losses reduction.

   INVERTER PROPULSION EQUIPMENT FOR GROUND TRANSPORTATION SYSTEMS
By G. Bocchetti; G. Giannini [View]
[Download]

Abstract: The market availability of high-rated power semiconductors IGBT (Insulated Gate Bipolar Transistor) is allowing design and manufacture of a new generation of improved converters, relying on VVVF (Variable Voltage Variable Frequency) inverter and induction motor technology. This paper mainly concerns applications for subway and light rail vehicles, at line voltage 750 Vdc with IGBT inverter with 1700 V devices connected in parallel. In the paper we describe the technical solution, the drive characteristics and the test results.

   DSP CONTROL OF A SYNCHRONOUS RELUCTANCE MOTOR
By J.E. Fletcher; B.W. Williams; T.C. Green [View]
[Download]

Abstract: This paper investigates torque control of a synchronous reluctance motor which has an axially laminated rotor. The drive system utilises a digital signal processor to control developed torque through current regulation. Equations for inductance ripple and associated torque ripple are derived. Direct torque measurement is used to estimate the relevant inductance ripple coefficients. The choice of current vector control scheme is examined with respect to torque ripple.

   THE DEVELOPMENT OF A BRUSHLESS DC DRIVE SYSTEM WITH AND WITHOUT SENSORS FOR WASHING MACHINES
By L. Tezduyar; R. N. Tunçay; M.E. Tacer [View]
[Download]

Abstract: This study deals with the development of a brushless dc (ECM) drive system for washing machines. Initially, the dynamic loading requirements of the washing machines have been recorded. The design methodology has been established. This methodology consists of the design of permanent magnet motor, their power electronic supply, sensing and control network. The simulation and measurement have been achieved and the correlation between experimental and theoretical results have been assessed. The sensorless drive is realized. The merits and demerits of the design methodology of brushless dc drive (with and without sensors) for washing machines have been evaluated.

   PRODUCTION OF HARMONICS IN CONVERTER TRACTION DRIVES
By G. Skarpetowski [View]
[Download]

Abstract: The harmonics associated with converter traction systems, their sources and their effect on the supply network are described. Analysis of the converter system in Time Domain (TD) and Frequency Domain (FD) is performed based on the distribution theory, using suitable mathematical models of the systems considered. Examples of simplified harmonics calculation, harmonics reduction techniques and the concept of active and passive filtering is presented.

   PARAMETERS AND SPEED ESTIMATION FOR INDUCTION MACHINES BASED ON DYNAMIC MODELS
By L.A.S. Ribeiro; C.B. Jacobina; A.M.N. Lima [View]
[Download]

Abstract: This paper proposes a linear estimation technique to determine the electrical parameters and speed of a three phase induction machine. In the proposed approach the estimation models are formulated using the alpha-operator. The .electrical parameters and the speed are obtained as the solution of a standard least squares problem. Among the proposed estimation models there are some specific ones to determine a single parameter as the rotor time constant or the speed. The experimental results of the proposed approach in the modeling of a 1.5kW three phase induction machine are presented.

   COMPARATIVE STUDY OF INVERTER-FED DRIVES WITH DIFFERENT MOTOR TYPES
By U. Schäfer [View]
[Download]

Abstract: Variable speed drives have become popular solutions in many applications. Most research and development activities have been concentrated on converter-based speed variation of conventional squirrel-cage induction motors. New drives usually need not to be operated directly by the mains, or they are custom-design drives such as traction drives. In these application fields, competitors to the squirrel cage induction motor have appeared. Recent research has put an emphasis on reluctance motors, three phase and polyphase permanent magnet motors, and transversal flux motors. Siguificant improvements in motor size, weight, and cost can be achieved with regard to the induction motor. The purpose of this paper is to point out the properties of the complete drive systems including power electronics. In order to get a quantitative comparison with respect to the state-of-the-art, all motors mentioned above are dimensioned for a typical specification. Then the appropriate power electronics circuit is designed. It is shown that significant improvements in motor properties can be achieved. On the other hand, most new motor conceptions lead to higher requirements in power electronics. Each drive system offers advantages for special applications. In general purpose drives, the induction motor fed by a pulse width modulated voltage source inverter will probably continue its success, while demands such as high efficiency or low size and weight will ask for other solutions.

   FOUR QUADRANT, LARGE POWER, IGBT VECTOR CONTROLLED, ADJUSTABLE SPEED DRIVE. DESIGN AND TEST
By R. Numeroli; E. Gatti; G. Torti; R. Kranenburg [View]
[Download]

Abstract: A large power (up to 1.2 MVA), four quadrant, VSI, IGBT drive system has been designed in order to improve the performances of a conventional unidirectional motor drive. A line-side converter is used instead of the usual diode bridge; it has the same structure of the motor side converter. This configuration allows bi-directional power flow, quasi-sinusoidal line currents, line power factor control and DC-link voltage control. Design and experimental results are shown for an 800 kV A drive, for a wind mill application.

   HARMONIC DISTORTION CAUSED BY ELECTRIC TRACTION VEHICLES WITH AC MOTORS FED BY DC SUPPLY SYSTEM - CAD ANALYSIS
By A. Szelag; W. Zajac; P.M. Martinez [View]
[Download]

Abstract: The problem of harmonic disturbances caused by the converters of an electric traction vehicle is discussed in the paper. Different frequency-domain and time-domain methods of analysis of harmonic in a current of a vehicle with a.c. drive are presented, with an emphasis put on CAD methods. As there are projects to introduce new types of rolling stock by Polish State Railways (PKP) some introductory analyses have been undertaken in order to estimate the current harmonics in the overhead catenary caused by vehicle's converters, when supplied be a weak DC feeding network. Different factors influencing an uncharacteristic harmonics occurence in the vehicle's current are presented. As a type of rolling stock, supplied by a 3 kV DC traction system, a multiple unit and an universal locomotive with AC. motors are taken into consideration.

   STABILITY PROBLEMS OF ASYNCHRONOUS MACHINES FOR RAILWAYS PURPOSES
By K.S. Kim; M. Poloujadoff; J. Bavard; G. Mfonkeu [View]
[Download]

Abstract: The works presented in this paper are devoted to the studies of the stability and control of an asynchronous system for railway application. The open loop stability of the system is studied by simulation. Two types of control which are able to ensure the stability are proposed.

   Application of Fuzzy control for PWM voltage source inverter fed Permanent Magnet Synchronous Motor
By S. Grundmann; M. Krause; V. Müller; B.S.R. Iyengar [View]
[Download]

Abstract: A new approach for realising high dynamic performance drive system with permanent magnet synchronous motor (PMSM) fed by pulse width modulated (PWM) voltage source inverter (VSI) is presented. It is based on the application of non-linear Fuzzy cOntroller with inbuilt decoupling between the machine torque and flux encompassed by vector control principle. Block orientated simulation system DS88 has been combined with a design tool for a multipurpose Fuzzy controller. Speed and flux regulator outputs constitute as inputs for the Fuzzy controller to realise the desired system response characteristic. The efficacy of the method is established through a comparision of extensive simulation study results with practical results obtained on a laboratory size machine employing current controlled VSI fed PWM inverter with field orientation. Effects of external disturbances and load variations on the performance of the drive system are studied and results of analysis are presented.

   SLIDING MODE CONTROL OF INDUCTION MOTOR PHASE CURRENTS
By R.B. Hansen; T. Hattel; J. Bork; H. Rasmussen [View]
[Download]

Abstract: Sliding Mode control of induction motor phase currents are investigated through development of two control concepts. The first concept presented involves sliding mode current control by direct switching of the power converter. In the second concept the sliding mode equivalent control signal is introduced by use of pulse width modulation.

   USE OF LC FILTERS IN HARD SWITCHING PWM INVERTER DRIVES
By H. van der Broeck; Chr. Loef [View]
[Download]

Abstract: Hard switching PWM inverter drives cause high duldt stress at the motor windings and asymmetrical HF interference currents (EMI). Both problems can be overcome by inserting additional LC filters between motor and inverter. It is investigated how the filter has to be designed for providing sinusoidal motor voltages. The additional currents caused by the filter are determined. Apart from simulations, experimental results are presented.

   IMPROVEMENTS FOR INDUCTION MACHINE VECTOR CONTROL
By S. Wade; M. W. Dunnigan; B. W. Williams [View]
[Download]

Abstract: Several improvements to the vector control of induction machines are presented. Parameter identification of the rotor time constant using the extended Kalman filter (EKF) is improved by including the effects of machine core losses. This is used to improve the machine model for the vector controller - giving more accurate torque response. Triplen harmonic injection is shown to extend machine operation before field weakening occurs. Deadbanding is implemented to reduce current controlled inverter switching losses. A Motorola 96002 DSP based hardware system is used to implement these methods.

EPE 1995 - 27 - Dialogue Session DS1c: Adjustable Speed Drives
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 27 - Dialogue Session DS1c: Adjustable Speed Drives
	[return to parent folder]

	TWO PHASE SWITCHED RELUCTANCE DRIVE WITH NEW POWER ELECTRONIC CONVERTER FOR LOW COST APPLICATIONS By M. Barnes; C. Pollock	[View] [Download]
Abstract: The two phase switched reluctance motor requires fewer power electronic components and is easier to construct than its three and four phase equivalents. This paper presents experimental results of a two phase, 1 kW, switched reluctance drive, with high efficiency and a power to weight ratio considerably better than many commercially available alternatives. It is therefore suitable for high volume, low power applications, for which it is cheaper than conventional three and four phase switched reluctance drives. Central to the low cost of the drive, is the use of a novel two phase power electronic converter, which offers cost effective utilisation of power electronic components.

	ROTOR TIME CONSTANT COMPENSATION OF AN INDUCTION MOTOR IN INDIRECT VECTOR CONTROLLED DRIVES By A. A. Ganji; P. Lataire	[View] [Download]
Abstract: In order to obtain high performance indirect vector control, an on-line rotor time constant (Tr) identification/compensation method has to be included in the drive strategy. In this paper two Tr tracking algorithms, which use the misalignment of the rotor flux vector as an error caused by incorrect rotor time constant are presented. These techniques were evaluated on a commercially available converter.

	ON LINE TUNING OF ROTOR FLUX OBSERVERS FOR FIELD ORIENTED DRIVES USING IMPROVED STATOR BASED FLUX ESTIMATOR FOR LOW SPEEDS By E.K.K. Sng; A.C. Liew	[View] [Download]
Abstract: The paper describes a model-reference adaptive system (MRAS) used for tuning the rotor time constant or motor speed of an induction motor at low speeds. Tuning of stator parameters using high frequency signals also take place simultaneously to enable the state used by the MRAS to be accurate even at low speeds. Stability and dynamics ofMRAS are presented and verified experimentally on an induction motor at zero speed. Observer of rotor flux based on tUned rotor speed is shown to preserve field orientation at low speeds.

	IGBT DRIVE FOR CONTAINER STACKING CRANES WITH BIDIRECTIONAL SUPPLY By W.A.G. De Jager; G.H. Tubbing	[View] [Download]
Abstract: This paper deals with an asynchronous variable speed drive developed by Holec Ridderkerk for crane applications. This drive, based on IGBT technology, will be used on a 3 kV / 50 Hz mains supply. Behind a line transformer, the first stage in the power conversion is a controlled 3 phase bridge which feeds a dc-link. The second stage of the drive is a motor inverter. Control of the line-side converter is performed with hysteresis control, while the motor converter is controlled with digital vector control.

	INTELLIGENT MODELS FOR ELECTROMECHANICAL SYSTEMS By P.J. Costa Branco; J.A. Dente	[View] [Download]
Abstract: This paper proposes apply fuzzy learning techniques for modeling electromechanical systems, incorporating learning capabilities into the control system to adjust itself to the different operating conditions. Compensation of non - linear terms affecting system dynamics and implementation of "intelligent" systems with self-learning capabilities are the main applications for this new association. Three fuzzy algorithms are presented, learning from examples the rules expressing system behavior regardless of having analytical dependency or not. To investigate the association between electromechanical systems and fuzzy modeling, an experimental system composed by an electro-hydraulic position system is used. The performance of the algorithms will be compared and studied for different cases like systems modeling in a direct and indirect way, the number of need examples to build a reasonable model, the different learning capabilities of each algorithm and their use of the accessible information.

	PARAMETERS AND VOLT-AMPERE RATINGS OF A SYNCHRONOUS MOTOR DRIVE FOR FLUX-WEAKENING APPLICATIONS By N. Bianchi; S. Bolognani	[View] [Download]
Abstract: This paper deals with the characterisation of the motor parameters as well as of the inverter power ratings of a synchronous motor drive able to cover a desired flux-weakening operation range. The motor drive selection data are reported, in" normalised values, in several figures, by which one can derive the more suitable synchronous motor (defined by its d-q axis inductances and flux linkage) and the related inverter volt-ampere ratings.

	INVESTIGATIONS ON A HIGH-SPEED SWITCHED RELUCTANCE DRIVE INCORPORATING AMORPHOUS IRON By K. Backhaus; L. Link; J. Reinert	[View] [Download]
Abstract: High-speed direct drive applications combine outstanding demands on rugged rotor design and high efficiency. A novel solution might be realized by using a switched reluctance motor with rotor laminations made from amorphous iron. This paper comprises a switched reluctance motor and controller design as well as examinations of overall performance of the drive system.

	VOLTAGE PEAKS OF LOW VOLTAGE INDUCTION MOTORS DUE TO PWM INVERTER SUPPLY By B. Kawkabani; J.J. Simond; F. Kehtari	[View] [Download]
Abstract: In industrial variable speed drives, the supply of low voltage induction motors by IGBT-PWM inverters through screened cables may cause dangerous over-voltage surges at the motor terminals. These voltage peaks of about twice the dc link voltage, with a short rise time of about 200 nsec, increase the armature insulation stress and may damage the motor insulation. The present study provides a theoretical approach to this matter and is completed by tests performed on two 3 and 7.5 kW drives, with different cable lengths. Its target is to define the properties of these voltage peaks, their dependency on the installation parameters, and to present two measures to reduce the voltage gradient duldt or the peak voltages at the motor terminals in order to raise motor lifetime of such a.c motors.

	ELASTIC FUZZY CONTROLLER AND SLIDING MODE POWER INVERTER FOR ELECTROMECHANICAL POSITIONERS By J.C. Quadrado; J.F. Silva	[View] [Download]
Abstract: The computation algorithm, some implementation details, the design of sliding mode controlled short circuit proof power inverter, and the experimental performances of an elastic fuzzy controller for electromechanical. positioners are presented. Simulation and laboratory results are compared and attest the expected features of the controller like steady state error elimination, robustness and losses reduction.

	INVERTER PROPULSION EQUIPMENT FOR GROUND TRANSPORTATION SYSTEMS By G. Bocchetti; G. Giannini	[View] [Download]
Abstract: The market availability of high-rated power semiconductors IGBT (Insulated Gate Bipolar Transistor) is allowing design and manufacture of a new generation of improved converters, relying on VVVF (Variable Voltage Variable Frequency) inverter and induction motor technology. This paper mainly concerns applications for subway and light rail vehicles, at line voltage 750 Vdc with IGBT inverter with 1700 V devices connected in parallel. In the paper we describe the technical solution, the drive characteristics and the test results.

	DSP CONTROL OF A SYNCHRONOUS RELUCTANCE MOTOR By J.E. Fletcher; B.W. Williams; T.C. Green	[View] [Download]
Abstract: This paper investigates torque control of a synchronous reluctance motor which has an axially laminated rotor. The drive system utilises a digital signal processor to control developed torque through current regulation. Equations for inductance ripple and associated torque ripple are derived. Direct torque measurement is used to estimate the relevant inductance ripple coefficients. The choice of current vector control scheme is examined with respect to torque ripple.

	THE DEVELOPMENT OF A BRUSHLESS DC DRIVE SYSTEM WITH AND WITHOUT SENSORS FOR WASHING MACHINES By L. Tezduyar; R. N. Tunçay; M.E. Tacer	[View] [Download]
Abstract: This study deals with the development of a brushless dc (ECM) drive system for washing machines. Initially, the dynamic loading requirements of the washing machines have been recorded. The design methodology has been established. This methodology consists of the design of permanent magnet motor, their power electronic supply, sensing and control network. The simulation and measurement have been achieved and the correlation between experimental and theoretical results have been assessed. The sensorless drive is realized. The merits and demerits of the design methodology of brushless dc drive (with and without sensors) for washing machines have been evaluated.

	PRODUCTION OF HARMONICS IN CONVERTER TRACTION DRIVES By G. Skarpetowski	[View] [Download]
Abstract: The harmonics associated with converter traction systems, their sources and their effect on the supply network are described. Analysis of the converter system in Time Domain (TD) and Frequency Domain (FD) is performed based on the distribution theory, using suitable mathematical models of the systems considered. Examples of simplified harmonics calculation, harmonics reduction techniques and the concept of active and passive filtering is presented.

	PARAMETERS AND SPEED ESTIMATION FOR INDUCTION MACHINES BASED ON DYNAMIC MODELS By L.A.S. Ribeiro; C.B. Jacobina; A.M.N. Lima	[View] [Download]
Abstract: This paper proposes a linear estimation technique to determine the electrical parameters and speed of a three phase induction machine. In the proposed approach the estimation models are formulated using the alpha-operator. The .electrical parameters and the speed are obtained as the solution of a standard least squares problem. Among the proposed estimation models there are some specific ones to determine a single parameter as the rotor time constant or the speed. The experimental results of the proposed approach in the modeling of a 1.5kW three phase induction machine are presented.

	COMPARATIVE STUDY OF INVERTER-FED DRIVES WITH DIFFERENT MOTOR TYPES By U. Schäfer	[View] [Download]
Abstract: Variable speed drives have become popular solutions in many applications. Most research and development activities have been concentrated on converter-based speed variation of conventional squirrel-cage induction motors. New drives usually need not to be operated directly by the mains, or they are custom-design drives such as traction drives. In these application fields, competitors to the squirrel cage induction motor have appeared. Recent research has put an emphasis on reluctance motors, three phase and polyphase permanent magnet motors, and transversal flux motors. Siguificant improvements in motor size, weight, and cost can be achieved with regard to the induction motor. The purpose of this paper is to point out the properties of the complete drive systems including power electronics. In order to get a quantitative comparison with respect to the state-of-the-art, all motors mentioned above are dimensioned for a typical specification. Then the appropriate power electronics circuit is designed. It is shown that significant improvements in motor properties can be achieved. On the other hand, most new motor conceptions lead to higher requirements in power electronics. Each drive system offers advantages for special applications. In general purpose drives, the induction motor fed by a pulse width modulated voltage source inverter will probably continue its success, while demands such as high efficiency or low size and weight will ask for other solutions.

	FOUR QUADRANT, LARGE POWER, IGBT VECTOR CONTROLLED, ADJUSTABLE SPEED DRIVE. DESIGN AND TEST By R. Numeroli; E. Gatti; G. Torti; R. Kranenburg	[View] [Download]
Abstract: A large power (up to 1.2 MVA), four quadrant, VSI, IGBT drive system has been designed in order to improve the performances of a conventional unidirectional motor drive. A line-side converter is used instead of the usual diode bridge; it has the same structure of the motor side converter. This configuration allows bi-directional power flow, quasi-sinusoidal line currents, line power factor control and DC-link voltage control. Design and experimental results are shown for an 800 kV A drive, for a wind mill application.

	HARMONIC DISTORTION CAUSED BY ELECTRIC TRACTION VEHICLES WITH AC MOTORS FED BY DC SUPPLY SYSTEM - CAD ANALYSIS By A. Szelag; W. Zajac; P.M. Martinez	[View] [Download]
Abstract: The problem of harmonic disturbances caused by the converters of an electric traction vehicle is discussed in the paper. Different frequency-domain and time-domain methods of analysis of harmonic in a current of a vehicle with a.c. drive are presented, with an emphasis put on CAD methods. As there are projects to introduce new types of rolling stock by Polish State Railways (PKP) some introductory analyses have been undertaken in order to estimate the current harmonics in the overhead catenary caused by vehicle's converters, when supplied be a weak DC feeding network. Different factors influencing an uncharacteristic harmonics occurence in the vehicle's current are presented. As a type of rolling stock, supplied by a 3 kV DC traction system, a multiple unit and an universal locomotive with AC. motors are taken into consideration.

	STABILITY PROBLEMS OF ASYNCHRONOUS MACHINES FOR RAILWAYS PURPOSES By K.S. Kim; M. Poloujadoff; J. Bavard; G. Mfonkeu	[View] [Download]
Abstract: The works presented in this paper are devoted to the studies of the stability and control of an asynchronous system for railway application. The open loop stability of the system is studied by simulation. Two types of control which are able to ensure the stability are proposed.

	Application of Fuzzy control for PWM voltage source inverter fed Permanent Magnet Synchronous Motor By S. Grundmann; M. Krause; V. Müller; B.S.R. Iyengar	[View] [Download]
Abstract: A new approach for realising high dynamic performance drive system with permanent magnet synchronous motor (PMSM) fed by pulse width modulated (PWM) voltage source inverter (VSI) is presented. It is based on the application of non-linear Fuzzy cOntroller with inbuilt decoupling between the machine torque and flux encompassed by vector control principle. Block orientated simulation system DS88 has been combined with a design tool for a multipurpose Fuzzy controller. Speed and flux regulator outputs constitute as inputs for the Fuzzy controller to realise the desired system response characteristic. The efficacy of the method is established through a comparision of extensive simulation study results with practical results obtained on a laboratory size machine employing current controlled VSI fed PWM inverter with field orientation. Effects of external disturbances and load variations on the performance of the drive system are studied and results of analysis are presented.

	SLIDING MODE CONTROL OF INDUCTION MOTOR PHASE CURRENTS By R.B. Hansen; T. Hattel; J. Bork; H. Rasmussen	[View] [Download]
Abstract: Sliding Mode control of induction motor phase currents are investigated through development of two control concepts. The first concept presented involves sliding mode current control by direct switching of the power converter. In the second concept the sliding mode equivalent control signal is introduced by use of pulse width modulation.

	USE OF LC FILTERS IN HARD SWITCHING PWM INVERTER DRIVES By H. van der Broeck; Chr. Loef	[View] [Download]
Abstract: Hard switching PWM inverter drives cause high duldt stress at the motor windings and asymmetrical HF interference currents (EMI). Both problems can be overcome by inserting additional LC filters between motor and inverter. It is investigated how the filter has to be designed for providing sinusoidal motor voltages. The additional currents caused by the filter are determined. Apart from simulations, experimental results are presented.

	IMPROVEMENTS FOR INDUCTION MACHINE VECTOR CONTROL By S. Wade; M. W. Dunnigan; B. W. Williams	[View] [Download]
Abstract: Several improvements to the vector control of induction machines are presented. Parameter identification of the rotor time constant using the extended Kalman filter (EKF) is improved by including the effects of machine core losses. This is used to improve the machine model for the vector controller - giving more accurate torque response. Triplen harmonic injection is shown to extend machine operation before field weakening occurs. Deadbanding is implemented to reduce current controlled inverter switching losses. A Motorola 96002 DSP based hardware system is used to implement these methods.