EPE Association: EPE 1993 - 31 - Dialogue Session DS1.7: CONTROL: STRATEGIES

EPE 1993 - 31 - Dialogue Session DS1.7: CONTROL: STRATEGIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 31 - Dialogue Session DS1.7: CONTROL: STRATEGIES

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   MULTI CONVERTER IMPLEMENTATION BY PARALLEL ASSOCIATION OF K VOLTAGE SOURCE CONVERTERS - CONTROL METHOD
By L. Matakas Jr.; E. Masada [View]
[Download]

Abstract: Recently there is a demand for high power, high performance converters . Multi converters can satisfy not only the higher power ratings , but also presents a higher output frequency and a multi level behavior with the existing low speed power devices. After a brief review of the state of art on multiconverters implementations of voltage source converters, this paper wimm compare the existing options according to their harmonics spectra, components stresses and available quantifying levels. Necessary conditions for multilevel waveform synthesis are discussed. This paper emphasizes the parallel association of converters. lt is simple, has low cost and can be operated even at the occurrence of the loss of some converters. Considerations about the control methods and simulation results are also shown.

   ADAPTIVE TIME OPTIMAL CONTROL OF THYRISTOR CONVERTER CURRENT
By Z. Kovacic; S. Bogdan; Z. Ban; P. Crnosija [View]
[Download]

Abstract: Based on a fast on-line parameter estimation algorithm, a new adaptation procedure, applied to the time optimal current control of a thyristor converter loaded with a dc motor is presented. A time optimal current control algorithm ensures that in case of rated system parameter values a new steady state value is reached within a single current pulsation even when operating modes (continuous, discontinuous) are changed. In case of changed system parameter values, the proposed adaptation mechanism enables the current response to be completed within two current pulsations, thus keeping it time optimal and making it insensitive to parameter variations. Estimation and adaptation algorithms were verified by computer simulation and the results obtained are presented in the paper.

   A TRACKING BANDPASS FILTER FOR THE REJECTION OF POWER SYSTEM DISTURBANCES
By Jane Jaques; F. P. Dawson; R. Bonert [View]
[Download]

Abstract: This paper presents a bandpass filter topology suitable for tracking the fundamental frequency component of a monitored AC waveform with no phase shift between the input and output. Online dynamic phase angle information is preserved in the process. The filter is capable of rejecting severe disturbances, yet tracking langer term frequency changes. The following filters are considered: adaptive biquadratic notch filter, adaptive biquadratic bandpass filter, combined adaptive bandpass filter of arbitrary order with a phase locked loop. The latter approach is taken in that it provides the greatest amount of flexibility. Results are verified experimentally with the use of an adaptive switched capacitor bandpass filter.

   32 BITS HIGH PERFORMANCE SINGLE CHIP MICROCONTROLLER MC68332 FOR THE CONTROL OF CYCLOCONVERTER
By A. S. Zein El-Din; J. Faubry; S. A. Mahmoud [View]
[Download]

Abstract: The increasing availability of single chip low cost microcontroller has provided an inexpensive, flexible, and sophisticated means for electronic control. The use of microcontrollers rather than microprocessors to keep equipment compact, reduce the number of components and improve reliability. There is much interest in using microcontroller 32 bit MC68332 (Motorola), combining high - performance data manipulation capabilities with powerful peripheral subsystems, HCMOS technology for firing and controlling of cycloconverter. This paper represents, the simplified (3 phase ----> 1) and effected method of control of cycloconverter phase using the microcontroller MC68332. Comparison between the expermintal results and simulation results of the load voltage and current in different values of output frequency has been done. Also spectrum analysis of the harmonics of the output voltage has been represented. The inputs phase and load currents corresponding for various values of the output frequency has been represented.

   EXTENDED CONTROL STRATEGY FOR A PWM LINE-FRIENDLY AC-TO-DC CONVERTER
By R. Marschalko [View]
[Download]

Abstract: A three-phase dc-link, IGBT, PWM converter was formerly in detail studied. The applied control strategies used all the allowed switching opperations of the semiconductor devices such that the converter has a line-friendly performance. High dynamic and satisfactorily steady-state performances of the converter were obtained.Simulated results and careful experiments indicate a relatively significant dc-voltage drop at the output of the converter when the lead changes. In order to minimize this important modification of the dc-voltage level, more complex control strategies were studied. The desired line-friendly operation mode is kept active only for the lead values that are less as a prescribed one. If an overload appears, in motoring or generatering operation mode, nonactive power is generated, so that the dc-link voltage is kept constant.The paper deals with this control strategies and analyses comparatively the converter performances.

   REJECTION OF UNDESIRABLE EFFECTS OF INPUT DC-VOLTAGE RIPPLE IN SINGLE-PHASE P.W.M. INVERTERS
By J. Sakly; Ph. Delarue; R. Bausiere [View]
[Download]

Abstract: In this paper a new technique to cancel the effects of the ripple in the input DC-voltage of single-phase full-bridge voltage-source PWM inverters is discussed. From the analysis of the inverter output voltage, it is shown that its harmonic components are considerably affected by the input DC-voltage ripple, when the same PWM control scheme as for a constant input voltage is used. More precisely low order harmonics appear in the output voltage which are difficult to filter. With this new proposal based on the notion of conversion function, it is possible to reject all the low order harmonic components of the output voltage. Trade-offs involved in acquiring the immunity to DC-link voltage ripple are also discussed. Selected experimental results are presented. They show good concordance with expected results.

   PWM SWITCHING PATTERNS FOR OPERATING A 3-PHASE INVERTER BRIDGE AS A BOOST CONVERTER
By John C. Salmon [View]
[Download]

Abstract: This paper describes how the boost-action of an inverter bridge is influenced by the inverter pwm switching patterns. The inverter boost-action presented in the paper assumes that the 3-phase pwm voltages at the inverter bridge output terminals are not corrupted. The maximum permissible voltage gain of the inverter boost-action is shown to be dependent upon the amplitude modulation depth and to a limited extent by the type of reference waveform used. Analysis of the reference waveforms is used to predict the inverter boost-gain and good agreement is obtained between these predictions and results obtained from analysis of pwm switching patterns. Operating bounds for the inventer boost-action are linked with the ripple associated with three-phase rectified voltages and also with the inverter boost-gain fluctuations.

   DYNAMICS AND ANALYSIS OF A THREE PHASE AC POWER CONVERTERS
By P. Bauer; J. B. Klaassens [View]
[Download]

Abstract: Dynamical analysis of dc/dc switched converters is extensively presented in literature as a design tool. This paper shows a systematic approach and methods for solving the dynamical analysis for ac power converters. Two possible approaches: "rotating frame" and "sliding mode equivalent control" are analyzed. The result is a linear time-invariant system which can be investigated with already known techniques.

   A NEW CONTROL STRATEGY OF QUASl-CYCLOCONVERTER FED INDUCTION MOTOR DRIVE
By M. Adli; R. Mecke; F. Palis [View]
[Download]

Abstract: The utilization of microcomputer based control devices has led to highly sophisticated power converters and to an increasing use of ac-drive systems. However, microcomputer control devices assist as well in creating power converters which are characterized by a most simple structure and for that reason low manufacture costs. From the power electronic point of view current source inverters are known as very simple, reliable and economical converters. Moreover, they permit the recuperation of energy. On the other hand, the need for a large inductance in the dc-circuit in order to decouple the net converter from the machine converter represents a considerable disadvantage. The presented paper aims at their decoupling by using an especial control strategy of both the net converter and the machine converter. Because of the direct coupling of them without using energy stocking elements, the presented system is called quasi-cycloconverter. It is shown that quasi-cycloconverter fed ac-drives are able to cope with high dynamic requirements if field oriented control is used.

   TRANSPUTER BASED CURRENT-FORCED CONTROL OF A REVERSIBLE RECTIFIER
By H. Zhang; B. E. Mulhall [View]
[Download]

Abstract: At the present state of technology the PWM reversible rectifier offers a practical route to high-quality conversion of a.c. to d.c. The control schemes for a reversible rectifier have recently been the subject of intensive study. This paper presents a digital implementation of a current-forced control scheme using a transputer. A control algorithm suitable for real-time control is introduced and a programming model using OCCAM is utilised. Experimental results are presented to demonstrate the performance of the proposed control scheme.

   CONTROL STRATEGY OF MATRIX CONVERTERS
By T. J. Sobczyk [View]
[Download]

Abstract: This paper describes a new control strategy for a matrix converter that transforms an N-phase system with frequency f1 directly to an M-phase system with frequency f2. In this converter each branch can conduct current in both directions and can be switched on and switched off by semiconductor power electronic devices in an arbitrary time instant. This control strategy is mathematically described by relationships between state functions that determine the state of each converter branch. lt is proved that this strategy keeps symmetry in both input and output systems of voltages and currents. Reinterpretation of the state functions as functions of two variables and its geometrical representation is shown, which leads to a very simply determination of the time instants of the state changes of each converter branch. As an example, the time instants of state changes of all serniconductor power switching devices for a 3-phase to 3-phase frequency converter is determined.

   NONLINEAR DECOUPLING CONTROL STRATEGY FOR VARIABLE FREQUENCY INDUCTION MOTOR SYSTEM FED BY HYSTERESIS-BAND CURRENT-CONTROLLED PWM INVERTER
By B. Chen; Y. Ruan; Y. Xu; S. Gong [View]
[Download]

Abstract: The dynamic model of induction motor fed by hysteresis-band current-controlled PWM inverter is a nonlinear multivariable system with strong coupling. In this paper, the theory of feedback linearization for nonlinear systems is applied to realize linearization and decoupling of this control object with consideration of the time delay of hysteresis band. As a result, two linear subsystems-rotor speed subsystem and rotor flux linkage subsystem are obtained. The regulators of these two linear subsystems can be easily designed by ordinary method based on linear theory. An AC variable frequency speed-regulating system is formed with the nonlinear decoupling algorithm incoporated in a 8096 single-chip microcomputer. Finally, experimental results show that the dynamic behaviour of this system is excellent.

   A HYSTERESIS CURRENT CONTROL FOR PARALLEL CONNECTED LINE-SIDE CONVERTERS OF AN INVERTER LOCOMOTIVE
By Markus Meyer; Astrid Sonnenmoser [View]
[Download]

Abstract: Inverter locomotives have become a standard solution in modern rail transportation. Up to now the suboscillation method for pulsewidth modulation has been widely used for the control of their lineside converters. Future requirements such as faster power control, well defined response in the case of a distorted line voltage or the installation of active filters demand for new modulation schemes. The paper introduces a modulation method which is based on a hysteresis current control. lt is suited for parallel connected voltage source inverters and combines the advantages of both the hysteresis control and the suboscillation method. This lncludes the dynamic performance as well as the staggered firing of the converters in order to reduce the total harmonic content of the line current. The design of this scheme, which is especially suited for locomotives with an active filter, Is explained and a comparison with the suboscillation method is presented. All results are based on computer simulations.

EPE 1993 - 31 - Dialogue Session DS1.7: CONTROL: STRATEGIES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 31 - Dialogue Session DS1.7: CONTROL: STRATEGIES
	[return to parent folder]

	MULTI CONVERTER IMPLEMENTATION BY PARALLEL ASSOCIATION OF K VOLTAGE SOURCE CONVERTERS - CONTROL METHOD By L. Matakas Jr.; E. Masada	[View] [Download]
Abstract: Recently there is a demand for high power, high performance converters . Multi converters can satisfy not only the higher power ratings , but also presents a higher output frequency and a multi level behavior with the existing low speed power devices. After a brief review of the state of art on multiconverters implementations of voltage source converters, this paper wimm compare the existing options according to their harmonics spectra, components stresses and available quantifying levels. Necessary conditions for multilevel waveform synthesis are discussed. This paper emphasizes the parallel association of converters. lt is simple, has low cost and can be operated even at the occurrence of the loss of some converters. Considerations about the control methods and simulation results are also shown.

	ADAPTIVE TIME OPTIMAL CONTROL OF THYRISTOR CONVERTER CURRENT By Z. Kovacic; S. Bogdan; Z. Ban; P. Crnosija	[View] [Download]
Abstract: Based on a fast on-line parameter estimation algorithm, a new adaptation procedure, applied to the time optimal current control of a thyristor converter loaded with a dc motor is presented. A time optimal current control algorithm ensures that in case of rated system parameter values a new steady state value is reached within a single current pulsation even when operating modes (continuous, discontinuous) are changed. In case of changed system parameter values, the proposed adaptation mechanism enables the current response to be completed within two current pulsations, thus keeping it time optimal and making it insensitive to parameter variations. Estimation and adaptation algorithms were verified by computer simulation and the results obtained are presented in the paper.

	A TRACKING BANDPASS FILTER FOR THE REJECTION OF POWER SYSTEM DISTURBANCES By Jane Jaques; F. P. Dawson; R. Bonert	[View] [Download]
Abstract: This paper presents a bandpass filter topology suitable for tracking the fundamental frequency component of a monitored AC waveform with no phase shift between the input and output. Online dynamic phase angle information is preserved in the process. The filter is capable of rejecting severe disturbances, yet tracking langer term frequency changes. The following filters are considered: adaptive biquadratic notch filter, adaptive biquadratic bandpass filter, combined adaptive bandpass filter of arbitrary order with a phase locked loop. The latter approach is taken in that it provides the greatest amount of flexibility. Results are verified experimentally with the use of an adaptive switched capacitor bandpass filter.

	32 BITS HIGH PERFORMANCE SINGLE CHIP MICROCONTROLLER MC68332 FOR THE CONTROL OF CYCLOCONVERTER By A. S. Zein El-Din; J. Faubry; S. A. Mahmoud	[View] [Download]
Abstract: The increasing availability of single chip low cost microcontroller has provided an inexpensive, flexible, and sophisticated means for electronic control. The use of microcontrollers rather than microprocessors to keep equipment compact, reduce the number of components and improve reliability. There is much interest in using microcontroller 32 bit MC68332 (Motorola), combining high - performance data manipulation capabilities with powerful peripheral subsystems, HCMOS technology for firing and controlling of cycloconverter. This paper represents, the simplified (3 phase ----> 1) and effected method of control of cycloconverter phase using the microcontroller MC68332. Comparison between the expermintal results and simulation results of the load voltage and current in different values of output frequency has been done. Also spectrum analysis of the harmonics of the output voltage has been represented. The inputs phase and load currents corresponding for various values of the output frequency has been represented.

	EXTENDED CONTROL STRATEGY FOR A PWM LINE-FRIENDLY AC-TO-DC CONVERTER By R. Marschalko	[View] [Download]
Abstract: A three-phase dc-link, IGBT, PWM converter was formerly in detail studied. The applied control strategies used all the allowed switching opperations of the semiconductor devices such that the converter has a line-friendly performance. High dynamic and satisfactorily steady-state performances of the converter were obtained.Simulated results and careful experiments indicate a relatively significant dc-voltage drop at the output of the converter when the lead changes. In order to minimize this important modification of the dc-voltage level, more complex control strategies were studied. The desired line-friendly operation mode is kept active only for the lead values that are less as a prescribed one. If an overload appears, in motoring or generatering operation mode, nonactive power is generated, so that the dc-link voltage is kept constant.The paper deals with this control strategies and analyses comparatively the converter performances.

	REJECTION OF UNDESIRABLE EFFECTS OF INPUT DC-VOLTAGE RIPPLE IN SINGLE-PHASE P.W.M. INVERTERS By J. Sakly; Ph. Delarue; R. Bausiere	[View] [Download]
Abstract: In this paper a new technique to cancel the effects of the ripple in the input DC-voltage of single-phase full-bridge voltage-source PWM inverters is discussed. From the analysis of the inverter output voltage, it is shown that its harmonic components are considerably affected by the input DC-voltage ripple, when the same PWM control scheme as for a constant input voltage is used. More precisely low order harmonics appear in the output voltage which are difficult to filter. With this new proposal based on the notion of conversion function, it is possible to reject all the low order harmonic components of the output voltage. Trade-offs involved in acquiring the immunity to DC-link voltage ripple are also discussed. Selected experimental results are presented. They show good concordance with expected results.

	PWM SWITCHING PATTERNS FOR OPERATING A 3-PHASE INVERTER BRIDGE AS A BOOST CONVERTER By John C. Salmon	[View] [Download]
Abstract: This paper describes how the boost-action of an inverter bridge is influenced by the inverter pwm switching patterns. The inverter boost-action presented in the paper assumes that the 3-phase pwm voltages at the inverter bridge output terminals are not corrupted. The maximum permissible voltage gain of the inverter boost-action is shown to be dependent upon the amplitude modulation depth and to a limited extent by the type of reference waveform used. Analysis of the reference waveforms is used to predict the inverter boost-gain and good agreement is obtained between these predictions and results obtained from analysis of pwm switching patterns. Operating bounds for the inventer boost-action are linked with the ripple associated with three-phase rectified voltages and also with the inverter boost-gain fluctuations.

	DYNAMICS AND ANALYSIS OF A THREE PHASE AC POWER CONVERTERS By P. Bauer; J. B. Klaassens	[View] [Download]
Abstract: Dynamical analysis of dc/dc switched converters is extensively presented in literature as a design tool. This paper shows a systematic approach and methods for solving the dynamical analysis for ac power converters. Two possible approaches: "rotating frame" and "sliding mode equivalent control" are analyzed. The result is a linear time-invariant system which can be investigated with already known techniques.

	A NEW CONTROL STRATEGY OF QUASl-CYCLOCONVERTER FED INDUCTION MOTOR DRIVE By M. Adli; R. Mecke; F. Palis	[View] [Download]
Abstract: The utilization of microcomputer based control devices has led to highly sophisticated power converters and to an increasing use of ac-drive systems. However, microcomputer control devices assist as well in creating power converters which are characterized by a most simple structure and for that reason low manufacture costs. From the power electronic point of view current source inverters are known as very simple, reliable and economical converters. Moreover, they permit the recuperation of energy. On the other hand, the need for a large inductance in the dc-circuit in order to decouple the net converter from the machine converter represents a considerable disadvantage. The presented paper aims at their decoupling by using an especial control strategy of both the net converter and the machine converter. Because of the direct coupling of them without using energy stocking elements, the presented system is called quasi-cycloconverter. It is shown that quasi-cycloconverter fed ac-drives are able to cope with high dynamic requirements if field oriented control is used.

	TRANSPUTER BASED CURRENT-FORCED CONTROL OF A REVERSIBLE RECTIFIER By H. Zhang; B. E. Mulhall	[View] [Download]
Abstract: At the present state of technology the PWM reversible rectifier offers a practical route to high-quality conversion of a.c. to d.c. The control schemes for a reversible rectifier have recently been the subject of intensive study. This paper presents a digital implementation of a current-forced control scheme using a transputer. A control algorithm suitable for real-time control is introduced and a programming model using OCCAM is utilised. Experimental results are presented to demonstrate the performance of the proposed control scheme.

	CONTROL STRATEGY OF MATRIX CONVERTERS By T. J. Sobczyk	[View] [Download]
Abstract: This paper describes a new control strategy for a matrix converter that transforms an N-phase system with frequency f1 directly to an M-phase system with frequency f2. In this converter each branch can conduct current in both directions and can be switched on and switched off by semiconductor power electronic devices in an arbitrary time instant. This control strategy is mathematically described by relationships between state functions that determine the state of each converter branch. lt is proved that this strategy keeps symmetry in both input and output systems of voltages and currents. Reinterpretation of the state functions as functions of two variables and its geometrical representation is shown, which leads to a very simply determination of the time instants of the state changes of each converter branch. As an example, the time instants of state changes of all serniconductor power switching devices for a 3-phase to 3-phase frequency converter is determined.

	NONLINEAR DECOUPLING CONTROL STRATEGY FOR VARIABLE FREQUENCY INDUCTION MOTOR SYSTEM FED BY HYSTERESIS-BAND CURRENT-CONTROLLED PWM INVERTER By B. Chen; Y. Ruan; Y. Xu; S. Gong	[View] [Download]
Abstract: The dynamic model of induction motor fed by hysteresis-band current-controlled PWM inverter is a nonlinear multivariable system with strong coupling. In this paper, the theory of feedback linearization for nonlinear systems is applied to realize linearization and decoupling of this control object with consideration of the time delay of hysteresis band. As a result, two linear subsystems-rotor speed subsystem and rotor flux linkage subsystem are obtained. The regulators of these two linear subsystems can be easily designed by ordinary method based on linear theory. An AC variable frequency speed-regulating system is formed with the nonlinear decoupling algorithm incoporated in a 8096 single-chip microcomputer. Finally, experimental results show that the dynamic behaviour of this system is excellent.

	A HYSTERESIS CURRENT CONTROL FOR PARALLEL CONNECTED LINE-SIDE CONVERTERS OF AN INVERTER LOCOMOTIVE By Markus Meyer; Astrid Sonnenmoser	[View] [Download]
Abstract: Inverter locomotives have become a standard solution in modern rail transportation. Up to now the suboscillation method for pulsewidth modulation has been widely used for the control of their lineside converters. Future requirements such as faster power control, well defined response in the case of a distorted line voltage or the installation of active filters demand for new modulation schemes. The paper introduces a modulation method which is based on a hysteresis current control. lt is suited for parallel connected voltage source inverters and combines the advantages of both the hysteresis control and the suboscillation method. This lncludes the dynamic performance as well as the staggered firing of the converters in order to reduce the total harmonic content of the line current. The design of this scheme, which is especially suited for locomotives with an active filter, Is explained and a comparison with the suboscillation method is presented. All results are based on computer simulations.