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Medvedev, Alexander
Publications (10 of 49) Show all publications
Stocks, M. & Medvedev, A. (2009). Linear-quadratic optimal time-varying observers with time-varying guaranteed convergence rate (ed.). IET Control Theory & Applications, 3(2), 181-188
Open this publication in new window or tab >>Linear-quadratic optimal time-varying observers with time-varying guaranteed convergence rate
2009 (English)In: IET Control Theory & Applications, ISSN 1751-8644, E-ISSN 1751-8652, Vol. 3, no 2, p. 181-188Article in journal (Refereed) Published
Abstract [en]

well-known method by Anderson and Moore for optimal quadratic feedback design with guaranteed constant convergence rate for linear time-invariant systems is generalised to linear complex-valued time-varying systems and time-varying convergence rates. The resulting method is readily applicable to observer design for state-affine systems and unifies methods developed there with the classical quadratic optimal state estimation and control. A pre-assigned time-varying convergence rate is shown to significantly improve the observer's transients in comparison with a constant one being employed for flux estimation in induction machines.

National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-10821 (URN)10.1049/iet-cta:20080055 (DOI)000263904900003 ()2-s2.0-60749087855 (Scopus ID)9b175950-13c4-11de-ae64-000ea68e967b (Local ID)9b175950-13c4-11de-ae64-000ea68e967b (Archive number)9b175950-13c4-11de-ae64-000ea68e967b (OAI)
Note

Validerad; 2009; 20090318 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stocks, M. & Medvedev, A. (2007). On-line estimation of all electrical parameters in induction machines subject to stator fault (ed.). In: (Ed.), IEEE International Conference on Control Applications, 2007 : CCA 2007: 1 - 3 Oct. 2007, Singapore ; [part of IEEE Multi-Conference on Systems and Control, MSC]. Paper presented at IEEE International Conference on Control Applications : 01/10/2007 - 03/10/2007 (pp. 527-532). Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>On-line estimation of all electrical parameters in induction machines subject to stator fault
2007 (English)In: IEEE International Conference on Control Applications, 2007 : CCA 2007: 1 - 3 Oct. 2007, Singapore ; [part of IEEE Multi-Conference on Systems and Control, MSC], Piscataway, NJ: IEEE Communications Society, 2007, p. 527-532Conference paper, Published paper (Refereed)
Abstract [en]

Identification of all the electrical parameters of Induction Machines (IMs) is a prerequisite for successful model-based control and/or fault detection. Most of the existing identification methods of symmetrical IMs are, strictly speaking, valid only at stationary conditions, which limitation results in either poor dynamics excitation or gross approximation errors, depending on the working conditions of the motor. In this paper, the topic of identification of all electrical parameters of faulty IMs is addressed for the first time. A method for on-line observer-based estimation of all electrical parameters of IMs with faulty stator is presented aiming primarily at fault tolerant control and fault detection. The approach does not rely on any assumptions regarding the rotor angular speed and/or acceleration.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2007
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-32776 (URN)10.1109/CCA.2007.4389285 (DOI)2-s2.0-43049168847 (Scopus ID)75e3e650-dfca-11dc-9e29-000ea68e967b (Local ID)978-1-4244-0443-8 (ISBN)75e3e650-dfca-11dc-9e29-000ea68e967b (Archive number)75e3e650-dfca-11dc-9e29-000ea68e967b (OAI)
Conference
IEEE International Conference on Control Applications : 01/10/2007 - 03/10/2007
Note

Godkänd; 2007; 20080220 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Stocks, M., Rodjukov, F. & Medvedev, A. (2006). Experimental validation of idealized two-axis models of faulty induction machines (ed.). In: (Ed.), 2006 American Control Conference: Minneapolis, MN, 14 - 16 June 2006. Paper presented at American Control Conference : 14/06/2006 - 16/06/2006 (pp. 1845-1850). Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>Experimental validation of idealized two-axis models of faulty induction machines
2006 (English)In: 2006 American Control Conference: Minneapolis, MN, 14 - 16 June 2006, Piscataway, NJ: IEEE Communications Society, 2006, p. 1845-1850Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, two dynamical models of the induction machine (IM) subject to electrical faults in the stator and rotor respectively are validated against experimental data. The considered stator faults are inter-turn short circuit in one of the phases and increased phase winding resistance. The rotor model is validated against an IM with one broken rotor bar, but otherwise healthy. The model parameters are estimated by the Gauss-Newton method and the obtained estimates are compared and discussed. The validation results show, for each of the considered faults, very good agreement between simulations and experiments. This makes the models promising in various applications involving asymmetric IM such as fault tolerant motor drives and motor condition monitoring.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2006
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-29599 (URN)10.1109/ACC.2006.1656488 (DOI)000241666303053 ()31e7ab60-96a8-11db-8975-000ea68e967b (Local ID)1-4244-0209-3 (ISBN)1-4244-0210-7 (ISBN)31e7ab60-96a8-11db-8975-000ea68e967b (Archive number)31e7ab60-96a8-11db-8975-000ea68e967b (OAI)
Conference
American Control Conference : 14/06/2006 - 16/06/2006
Note

Godkänd; 2006; 20061228 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Stocks, M. & Medvedev, A. (2006). Guaranteed convergence rate for linear-quadratic optimal time-varying observers (ed.). In: (Ed.), Proceedings of the 45th IEEE Conference on Decision and Control: San Diego, CA, 13 - 15 December 2006. Paper presented at IEEE Conference on Decision and Control : 13/12/2006 - 15/12/2006 (pp. 181-188). Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>Guaranteed convergence rate for linear-quadratic optimal time-varying observers
2006 (English)In: Proceedings of the 45th IEEE Conference on Decision and Control: San Diego, CA, 13 - 15 December 2006, Piscataway, NJ: IEEE Communications Society, 2006, p. 181-188Conference paper, Published paper (Refereed)
Abstract [en]

A well-known method by Anderson and Moore for optimal quadratic feedback design with guaranteed convergence rate for linear time-invariant systems is generalized to linear complex-valued time-varying systems and convergence rates. The resulting method is applied to observer design and illustrated by solving the problem of flux estimation in induction machines. A pre-assigned time-varying convergence rate is shown to improve the observer's transients in comparison with a constant one. The suggested design technique can be readily utilized for nonlinear state-affine systems

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2006
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-30448 (URN)10.1109/CDC.2006.376951 (DOI)442521f0-e15b-11dc-9e29-000ea68e967b (Local ID)1-4244-0170-4 (ISBN)442521f0-e15b-11dc-9e29-000ea68e967b (Archive number)442521f0-e15b-11dc-9e29-000ea68e967b (OAI)
Conference
IEEE Conference on Decision and Control : 13/12/2006 - 15/12/2006
Note

Godkänd; 2006; 20080222 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Stocks, M., Rodjukov, F. & Medvedev, A. (2006). Idealized two-axis model of induction machines under stator fault (ed.). In: (Ed.), 2006 1st IEEE Conference on Industrial Electronics and Applications: Singapore, 24 - 26 May 2006. Paper presented at IEEE Conference on Industrial Electronics and Applications : 24/05/2006 - 27/05/2006 (pp. 1-7). Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>Idealized two-axis model of induction machines under stator fault
2006 (English)In: 2006 1st IEEE Conference on Industrial Electronics and Applications: Singapore, 24 - 26 May 2006, Piscataway, NJ: IEEE Communications Society, 2006, p. 1-7Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, a low differential order model describing the dynamics of IMs with faulty stator is developed. The modelling is performed under well established idealizing assumptions regarding the magnetic and electrical properties of the motor. Typical motor faults as inter-turn short circuit and increased winding resistance are taken into account. The resulting model can be handled analytically and serve as a ground for fault detection and fault tolerant control of the IM. For each of the considered faults, very good agreement between simulations and experimental data collected from mass-produced industrial IMs is observed.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2006
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-38203 (URN)10.1109/ICIEA.2006.257203 (DOI)c8514b30-96a6-11db-8975-000ea68e967b (Local ID)0-7803-9514-X (ISBN)0-7803-9513-1 (ISBN)c8514b30-96a6-11db-8975-000ea68e967b (Archive number)c8514b30-96a6-11db-8975-000ea68e967b (OAI)
Conference
IEEE Conference on Industrial Electronics and Applications : 24/05/2006 - 27/05/2006
Note

Godkänd; 2006; 20061228 (ysko)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Stocks, M. & Medvedev, A. (2006). On observability and controllability of faulty induction machines (ed.). In: (Ed.), American Control Conference: Mineapolis, Minnesota, USA, June 14-16, 2006. Paper presented at American Control Conference : 14/06/2006 - 16/06/2006 (pp. 4399-4405). Piscataway, NJ: IEEE Communications Society
Open this publication in new window or tab >>On observability and controllability of faulty induction machines
2006 (English)In: American Control Conference: Mineapolis, Minnesota, USA, June 14-16, 2006, Piscataway, NJ: IEEE Communications Society, 2006, p. 4399-4405Conference paper, Published paper (Refereed)
Abstract [en]

In this paper an analysis of observability and controllability of the electrical part of faulty (non-symmetric) induction machines (IMs) is performed. A two-axis model of healthy or faulty IM is studied and the conditions under which it does not degenerate to a descriptor system are obtained. When degeneration does not occur and stator voltages, stator currents and the rotational angle/speed of the rotor are measured, a fault in the IM does not, in general, render the motor neither unobservable nor uncontrollable. However, it turns out that when the rotor resistance is very small, problems with observability and controllability still may arise.

Place, publisher, year, edition, pages
Piscataway, NJ: IEEE Communications Society, 2006
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-28125 (URN)10.1109/ACC.2006.1657411 (DOI)000241666308057 ()1cfaa7b0-96a9-11db-8975-000ea68e967b (Local ID)1-4244-0210-7 (ISBN)1cfaa7b0-96a9-11db-8975-000ea68e967b (Archive number)1cfaa7b0-96a9-11db-8975-000ea68e967b (OAI)
Conference
American Control Conference : 14/06/2006 - 16/06/2006
Note

Godkänd; 2006; 20061228 (ysko)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Stocks, M. & Medvedev, A. (2006). On-line estimation of all electrical parameters in symmetrical and faulty induction machines: stator fault case (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>On-line estimation of all electrical parameters in symmetrical and faulty induction machines: stator fault case
2006 (English)Report (Other academic)
Abstract [en]

Identification of all the electrical parameters of Induction Machines (IMs) is a prerequisite for successful model-based control and/or fault detection. Various approaches have been proposed previously: off-line experiments under alternating stationary conditions, least squares batch and on-line estimation, to name only a few. Both continuous and discrete time have been considered, all of them utilizing models for symmetrical IMs. Existing methods for identification of the electrical parameters of the IM are strictly speaking valid only at stationary conditions, which limitation results in either poor dynamics excitation or gross approximation errors, depending on the working conditions of the motor. Unrealistic assumptions about the rotor's angular acceleration are also often employed. The topic of identification of all electrical parameters of faulty IMs has not been addressed so far. In this paper, a method for on-line observer-based estimation of all electrical parameters of symmetrical IMs as well as IMs with faulty stator is presented aiming primarily at fault tolerant control and fault detection. The approach does not rely on any assumptions regarding the rotor's angular speed and/or acceleration.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2006. p. 50
Series
Technical report / Luleå University of Technology, ISSN 1402-1536 ; 2006:10
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-23440 (URN)7003b930-a4cf-11dc-8fee-000ea68e967b (Local ID)7003b930-a4cf-11dc-8fee-000ea68e967b (Archive number)7003b930-a4cf-11dc-8fee-000ea68e967b (OAI)
Note

Godkänd; 2006; 20071207 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Stocks, M., Rodjukov, F. & Medvedev, A. (2005). Idealized two-axis models of faulty induction machines (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Idealized two-axis models of faulty induction machines
2005 (English)Report (Other academic)
Abstract [en]

In this report a general framework for developing two-axis models for Induction Machines (IMs) with electrical faults is presented. It produces models that are of reasonably low differential order, suitable for mathematical analysis and can serve as a ground for fault detection and fault tolerant control of the IM. The modelling is performed by applying well established idealizing assumptions regarding the magnetic and electrical properties of the motor. In particular, models describing the IM subject to electrical faults in the stator and rotor are derived. Typical motor faults as inter-turn short circuit, increased winding resistance and broken rotor bars are taken into account. The models are validated against data collected from mass-produced industrial IMs. The validation shows very good agreement between simulations and experiment, for each of the considered faults. Finally, a stability proof for the derived models is presented enabling their use in control and monitoring applications.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2005. p. 22
Series
Research report / Luleå University of Technology, ISSN 1402-1528 ; 2005:05
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-24461 (URN)b0dce330-b29c-11db-bf9d-000ea68e967b (Local ID)b0dce330-b29c-11db-bf9d-000ea68e967b (Archive number)b0dce330-b29c-11db-bf9d-000ea68e967b (OAI)
Note

Godkänd; 2005; 20070202 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Birk, W., Arvanitidis, I., Medvedev, A. & Jönsson, P. (2003). Foam level control in a water model of the LD converter process (ed.). Control Engineering Practice, 11(1), 49-56
Open this publication in new window or tab >>Foam level control in a water model of the LD converter process
2003 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 1, p. 49-56Article in journal (Refereed) Published
Abstract [en]

This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.

National Category
Control Engineering Other Civil Engineering
Research subject
Control Engineering; Mining and Rock Engineering
Identifiers
urn:nbn:se:ltu:diva-5721 (URN)10.1016/S0967-0661(02)00178-8 (DOI)000180496300006 ()2-s2.0-0037274949 (Scopus ID)3e5d6460-6454-11db-8cbe-000ea68e967b (Local ID)3e5d6460-6454-11db-8cbe-000ea68e967b (Archive number)3e5d6460-6454-11db-8cbe-000ea68e967b (OAI)
Note

Validerad; 2003; 20061025 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Stocks, M. & Medvedev, A. (2002). Estimation of induction machine parameters at start-up using current envelope (ed.). In: (Ed.), Conference record of the 2002 IEEE Industry Applications Conference: 37th IAS annual meeting ; 13 - 18 October 2002, Pittsburgh, Pennsylvania, USA. Paper presented at IEEE Industry Applications Conference : 13/10/2002 - 18/10/2002 (pp. 1163-1170). Piscataway, NJ :: IEEE Communications Society
Open this publication in new window or tab >>Estimation of induction machine parameters at start-up using current envelope
2002 (English)In: Conference record of the 2002 IEEE Industry Applications Conference: 37th IAS annual meeting ; 13 - 18 October 2002, Pittsburgh, Pennsylvania, USA, Piscataway, NJ :: IEEE Communications Society, 2002, p. 1163-1170Conference paper, Published paper (Refereed)
Abstract [en]

A new method for estimation of electrical parameters in Induction Machines (IM) is presented. Evaluation of the parameters is performed by considering the envelope of the stator currents under motor start-up, thus avoiding the high sampling rates necessary for logging the actual currents. The use of start-up data makes the method attractive in the IM control and monitoring applications where the parameter estimates can be used for adjusting the control law or evaluating the motor condition. It is also demonstrated that the use of a simplified decoupled dynamic model of the IM in the estimation algorithm does not significantly worsen the quality of the obtained parameter estimates. Both simulations and experiments show fast convergence of the suggested algorithm.

Place, publisher, year, edition, pages
Piscataway, NJ :: IEEE Communications Society, 2002
National Category
Control Engineering
Research subject
Control Engineering
Identifiers
urn:nbn:se:ltu:diva-40004 (URN)10.1109/IAS.2002.1042706 (DOI)ef8216a0-0c50-11dd-9b51-000ea68e967b (Local ID)0-7803-7420-7 (ISBN)ef8216a0-0c50-11dd-9b51-000ea68e967b (Archive number)ef8216a0-0c50-11dd-9b51-000ea68e967b (OAI)
Conference
IEEE Industry Applications Conference : 13/10/2002 - 18/10/2002
Note

Godkänd; 2002; 20080417 (cira)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
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