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Leufvén, Oskar
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Publications (10 of 12) Show all publications
Leufvén, O. & Eriksson, L. (2016). Measurement, analysis and modeling of compressor flow for low pressure ratios. International journal of engine research, 17(2), 153-168
Open this publication in new window or tab >>Measurement, analysis and modeling of compressor flow for low pressure ratios
2016 (English)In: International journal of engine research, ISSN 1468-0874, Vol. 17, no 2, p. 153-168Article in journal (Other academic) Published
Abstract [en]

Increasingly stringent emissions legislation combined with consumer performance demands, have driven the development of downsized engines with complex turbocharger arrangements. To handle the complexity model-based methods have become a standard tool, and these methods need models that are capable of describing all operating modes of the systems. The models should also be easily parametrized and enable extrapolation. Both single and multiple stage turbo systems can operate with a pressure drop over their compressors, both stationary and transient. The focus here is to develop models that can describe centrifugal compressors that operate both in normal region and restriction region from standstill to maximum speed. The modeling results rely on an analysis of 305 automotive compressor maps, whereof five contain measured restriction operation, and two contain measured standstill characteristic. A standstill compressor is shown to choke at a pressure ratio of approximately 0.5, and the corresponding choking corrected mass flow being approximately 50% of the compressor maximum flow capacity. Both choking pressure ratio and flow are then shown to increase with corrected speed, and the choking pressure ratio is shown to occur at pressure ratios larger than unity for higher speeds. Simple empirical models are proposed and shown to be able to describe high flow and pressure ratios down to choking conditions well. A novel compressor flow model is proposed and validated to capture the high flow asymptote well, for speeds from standstill up to maximum.

Place, publisher, year, edition, pages
Sage Publications, 2016
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-92091 (URN)10.1177/1468087414562456 (DOI)000368815100001 ()
Note

Funding agencies: Vinnova Industry Excellence Center: LINK-SIC Linkoping Center for Sensor Informatics and Control

Vid tiden för disputation förelåg publikationen endast som manuskript

Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2018-01-30Bibliographically approved
Leufvén, O. & Eriksson, L. (2013). A surge and choke capable compressor flow model: Validation and extrapolation capability. Control Engineering Practice, 21(12), 1871-1883
Open this publication in new window or tab >>A surge and choke capable compressor flow model: Validation and extrapolation capability
2013 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 12, p. 1871-1883Article in journal (Refereed) Published
Abstract [en]

Increasingly stringent emissions legislation combined with consumer performance demand, have created the need for complex automotive engines. The control of these complex system rely heavily on control oriented models. Models capable of describing all operating modes of the systems are beneficial, and the models should be easily parametrized and enable extrapolation. A large database of automotive compressor maps is characterized, and used to develop, validate and automatically parametrize a compressor flow model capable of describing reversed flow, normal operation and choke. Measurement data from both an engine test stand, and a surge test stand, is used to parametrize and validate the surge capability of the model. The model is shown to describe all modes of operation with good performance, and also to be able to extrapolate to small turbo speeds. The extrapolation capability is important, since compressor maps are shown to lack information for low speeds, even though they frequently operate there in an engine installation.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-92090 (URN)10.1016/j.conengprac.2013.07.005 (DOI)000329017200023 ()
Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2018-01-30Bibliographically approved
Thomasson, A., Leufvén, O., Criscuolo, I. & Eriksson, L. (2013). Modeling and validation of a boost pressure actuation system, for a series sequentially turbocharged SI engine. Control Engineering Practice, 21(12), 1860-1870
Open this publication in new window or tab >>Modeling and validation of a boost pressure actuation system, for a series sequentially turbocharged SI engine
2013 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 12, p. 1860-1870Article in journal (Refereed) Published
Abstract [en]

An actuation system for flexible control of an advanced turbocharging system is studied. It incorporates a vacuum pump and tank that are connected to pulse width modulation controlled vacuum valves. A methodology for modeling the entire boost pressure actuation system is developed. Emphasis is placed on developing component models that are easily identified from measured data, without the need for expensive measurements.The models have physical interpretations that enable handling of varying surrounding conditions.The component models and integrated system are evaluated on a two stage series sequential turbo system with three actuators having different characteristics.Several applications of the developed system model are presented, including a nonlinear compensator for voltage disturbance rejection where the performance of the compensator is demonstrated on an engine in a test cell. The applicability of the complete system model for control and diagnosis of the vacuum system is also discussed.

Place, publisher, year, edition, pages
Elsevier / International Federation of Automatic Control, 2013
Keywords
Engine; Turbocharger; Vacuum system; Solenoid valve; Nonlinear compensator
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-103723 (URN)10.1016/j.conengprac.2013.01.004 (DOI)000329017200022 ()
Available from: 2014-01-24 Created: 2014-01-24 Last updated: 2018-01-30
Leufvén, O. (2013). Modeling for control of centrifugal compressors. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Modeling for control of centrifugal compressors
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Downsizing and turbocharging of engines provide a way to meet increasing demands for efficiency and performance in the automotive industry. An engine design is a result of compromises, e.g. the selection of charging system, and the trend is to reduce these compromises by increasing system complexity. Models have come to play a central role to handle this rise in complexity, and are used for simulation, system optimization and control synthesis. The models should describe the entire operating range, be capable of extrapolation, be easily parameterizable, and wide cover a range of applications.

A novel compressor model is developed which, in addition to the nominal operation, also covers surge, choke and operation at pressure ratios less than one. The model is based on data from more than 300 compressor maps, measurements from engine test stands, and a surge test stand. The general knowledge gained from the in-depth analysis is condensed in the model equations. The model can be automatically parametrized using a compressor map, is based on static functions for low computational cost, and is shown to extrapolate low speed compressor operation well. Furthermore, it is shown to be applicable to compressors of different size, ranging from small car applications to large heavy duty vehicles. Compressor restriction operation is modeled down to a standstill compressor, and shown to agree well with gas stand measurements. Further, the analysis contributes with new knowledge and models for choking pressure ratio and flow.

A method to automatically determine a turbo map, when the turbo is installed on an engine in an engine test stand is developed. The method can be used to validate manufacturer maps or expand the region covered in a map. An analysis of the limits that an engine installation imposes on the reachable points in the compressor map is performed. The addition of a throttle before the compressor is suggested to increase the reachable map region, and an engine and test cell control structure that can be used to automate the measurements is proposed. Two methods that compensate for the deviation between measured and desired speeds, are proposed and investigated. A gas stand map is compared to the map generated in the engine test stand, and a generally good agreement results.

An experimental analysis of the applicability of the commonly used correction factors, used for estimating compressor performance when the inlet conditions deviate from nominal, is performed. Correction factors are vital, to e.g. estimate turbocharger performance for driving at high altitude or to characterize second stage compressor performance, where the variations in inlet conditions are large. Measurements from an engine test stand and a gas stand show a small but clearly measurable trend, with decreasing compressor pressure ratio for decreasing compressor inlet pressure, for points with equal corrected shaft speed and corrected mass flow. A method that enables measurements to be analyzed with modified corrections is developed. As a result, an adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. p. 68
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1516
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-91384 (URN)978-91-7519-626-8 (ISBN)
Public defence
2013-05-24, Visionen, B-huset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2013-04-23 Created: 2013-04-23 Last updated: 2018-01-30Bibliographically approved
Leufvén, O. & Eriksson, L. (2012). Investigation of compressor correction quantities for automotive applications. International Journal of Engine Research, 13(6), 588-606
Open this publication in new window or tab >>Investigation of compressor correction quantities for automotive applications
2012 (English)In: International Journal of Engine Research, ISSN 1468-0874, E-ISSN 2041-3149, Vol. 13, no 6, p. 588-606Article in journal (Other academic) Published
Abstract [en]

Turbo performance is represented using maps, measured for one set of inlet conditions. Corrections are then applied to scale the performance to other inlet conditions. A turbo compressor for automotive applications experiences large variations in inlet conditions, and the use of two stage charging increases these variations. The variations are the motivation for analyzing the correction quantities and their validity. The corrections reveals a novel surge avoidance strategy, where the result is that a reduction in inlet pressure increases the surge margin for eight maps studied. The method to investigate the applicability of the strategy is general.

An experimental analysis of the applicability of the commonly used correction factors, used when estimating compressor performance for varying inlet conditions, is presented. The experimental campaign uses measurements from an engine test cell and from a gas stand, and shows a small, but clearly measurable trend, with decreasing compressor  pressure ratio for decreasing compressor inlet pressure. A method is  developed, enabling measurements to be analyzed with modified corrections.

An adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction. The resulting decrease in high altitude engine performance, due to compressor limitations, are quantified and shows a reduction in altitude of 200 – 600 m, for when engine torque has to be reduced to due limited compressor operation.

Place, publisher, year, edition, pages
SAGE Publications (UK and US) / Professional Engineering Publishing (Institution of Mechanical Engineers), 2012
Keywords
Experimental analysis; map; inlet conditions; speed line; measurements
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-64340 (URN)10.1177/1468087412439018 (DOI)000311831200004 ()
Available from: 2011-01-19 Created: 2011-01-19 Last updated: 2018-01-30Bibliographically approved
Criscuolo, I., Leufvén, O., Thomasson, A. & Eriksson, L. (2011). Model-Based Boost Pressure Control with System Voltage Disturbance Rejection. In: Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro (Ed.), Proceedings of the 18th IFAC World Congress, 2011. Paper presented at 2011 IFAC World Congress, Milano, Milano, Italy, 28 August - 2 September (pp. 5058-5063). International Federation of Automatic Control (IFAC)
Open this publication in new window or tab >>Model-Based Boost Pressure Control with System Voltage Disturbance Rejection
2011 (English)In: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, p. 5058-5063Conference paper, Published paper (Refereed)
Abstract [en]

Actuation systems for automotive boost control incorporate a vacuum tank and PWM controlled vacuum valves to increase the boosting system flexibility. Physical models for the actuator system are constructed using measurement data from a dynamometer with an engine having a two stage turbo system. The actuator model is integrated in a complete Mean Value Engine Model and a boost pressure controller is constructed. The developed model is used as basis for a nonlinear compensator, that is capable of rejecting disturbances from system voltage. An IMC based boost pressure controller is developed for the vacuum actuator and engine by using the engine model and then tested on the test cell. The controller performance is quantified and system voltage disturbance rejection is demonstrated.

Place, publisher, year, edition, pages
International Federation of Automatic Control (IFAC), 2011
Keywords
engine, turbocharger, vacuum system, solenoid valve, internal model control, nonlinear compensator
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-70391 (URN)10.3182/20110828-6-IT-1002.02214 (DOI)978-3-902661-93-7 (ISBN)
Conference
2011 IFAC World Congress, Milano, Milano, Italy, 28 August - 2 September
Available from: 2013-04-09 Created: 2011-09-06 Last updated: 2018-01-30Bibliographically approved
Leufven, O. & Eriksson, L. (2011). Surge and Choke Capable Compressor Model. In: Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro (Ed.), Proceedings of the 18th IFAC World Congress, 2011. Paper presented at 2011 IFAC World Congress, Milano, Milano, Italy, 28 August - 2 September (pp. 10653-10658). International Federation of Automatic Control (IFAC)
Open this publication in new window or tab >>Surge and Choke Capable Compressor Model
2011 (English)In: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, p. 10653-10658Conference paper, Published paper (Refereed)
Abstract [en]

A compressor model is developed. It is capable of representing mass flow and pressure characteristic for three different regions: surge, normal operation as well as for when the compressor acts as a restriction, i.e. having a pressure ratio of less than unity. Different submodels are discussed and methods to parametrize the given model structure are given. Both the parametrization and validation are supported extensively by measured data. Dynamic data sets include measurements from engine and surge test stands. The compressor model is further validated against a database of stationary compressor maps. The proposed model is shown to have good agreement with measured data for all regions, without the need for extensive geometric information or data.

Place, publisher, year, edition, pages
International Federation of Automatic Control (IFAC), 2011
Keywords
automobile powertrains, engine control, parameter estimation, restriction, turbo
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-70390 (URN)10.3182/20110828-6-IT-1002.00694 (DOI)978-3-902661-93-7 (ISBN)
Conference
2011 IFAC World Congress, Milano, Milano, Italy, 28 August - 2 September
Available from: 2013-04-09 Created: 2011-09-06 Last updated: 2018-01-30Bibliographically approved
Leufvén, O. (2010). Compressor Modeling for Control of Automotive Two Stage Turbochargers. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Compressor Modeling for Control of Automotive Two Stage Turbochargers
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

There is a demand for increasing efficiency of automotive engines, and one way to achieve this is through downsizing and turbocharging. In the design compromises are made, for example the maximum power of the engine determines the size of the compressor, but since the compressor mass flow range is limited, this affects the torque for low engine speeds. A two stage system, with two different sized turbochargers, reduces this compromise, but the system complexity increases. To handle the complexity, models have come to play a central role where they aid engineers in the design. Models are used in simulation, for design optimization and also in the control synthesis. In all applications it is vital that the models have good descriptive capabilities for the entire operating range studied.

A novel control oriented compressor model is developed, with good performance in the operating regions relevant for compressors in a two stage system. In addition to the nominal operating regime, also surge, choke and operation at pressure ratios less than unity, are modeled. The model structure can be automatically parametrized using a compressor map, and is based on static functions for low computational cost. A sensitivity analysis, isolating the important characteristics that influence surge transients in an engine is performed, and the gains of a novel surge controller are quantified.

A compressor map is usually measured in a gas stand, that has different surrounding systems, compared to the application where the compressor is used. A method to automatically determine a turbo map, when the turbo is installed on an engine in an engine test stand is developed. The map can then be used to parametrize the developed compressor model, and effectively create a model parametrized for its intended application.

An experimental analysis of the applicability of the commonly used correction factors, used for estimating compressor performance when the inlet conditions deviate from nominal, is presented. Correction factors are vital, to e.g. estimate turbocharger performance for driving at high altitude or to analyze second stage compressor performance, where the variations in inlet conditions are large. The experimental campaign uses measurements from an engine test cell and from a gas stand, and shows a small, but clearly measurable trend, with decreasing compressor pressure ratio for decreasing compressor inlet pressure, for points with equal corrected shaft speed and corrected mass flow. A method is developed, enabling measurements to be analyzed with modified corrections. An adjusted shaft speed correction quantity is proposed, incorporating also the inlet pressure in the shaft speed correction. A high altitude example is used to quantify the influence of the modified correction.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. p. 28
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1463
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-64342 (URN)LIU-TEK-LIC-2010:32 (Local ID)978-91-7393-254-7 (ISBN)LIU-TEK-LIC-2010:32 (Archive number)LIU-TEK-LIC-2010:32 (OAI)
Supervisors
Available from: 2011-01-19 Created: 2011-01-19 Last updated: 2018-01-30Bibliographically approved
Leufvén, O. & Eriksson, L. (2010). Engine Test Bench Turbo Mapping. Paper presented at SAE 2010 World Congress, April 13-15, Detroit, Michigan, USA. SAE International
Open this publication in new window or tab >>Engine Test Bench Turbo Mapping
2010 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A method for determining turbocharger performance on installations in an engine test bench is developed and investigated. The focus is on the mapping of compressor performance but some attention is also given to the turbine mapping. An analysis of the limits that an engine installation imposes on the reachable points in the compressor map is performed, in particular it shows what corrected flows and pressure ratios can be reached and what these limitations depend on. To be able to span over a larger  region of the corrected flow a throttle before the compressor is suggested and this is also verified in the test bench.

Turbocharger mapping is a time consuming process and there is a need for a systematic process that can be executed automatically. An engine and test cell control structure that can be used to automate and monitor the measurements by controlling the system to the desired operating points is also proposed.

In experiments, used for constructing the compressor speed lines, it is virtually impossible to control the turbocharger to the exact corrected speed that is postulated by the speed line. To overcome this two methods that compensate for the deviation between measured speed and the desired speed are proposed and investigated. Detailed data from a gas stand is used to evaluate the measurements compared to those that are generated in the engine test cell installation. The agreements are generally good but there is more noise in the engine data and there are also some small systematic deviations.

Place, publisher, year, edition, pages
SAE International, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-64337 (URN)10.4271/2010-01-1232 (DOI)
Conference
SAE 2010 World Congress, April 13-15, Detroit, Michigan, USA
Available from: 2011-01-19 Created: 2011-01-19 Last updated: 2018-01-30
Thomasson, A., Eriksson, L., Leufvén, O. & Andersson, P. (2009). Wastegate Actuator Modeling and Model-Based Boost Pressure Control. In: Antonio Sciarretta and Paolino Tona (Ed.), Proceedings of the 2009 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling: . Paper presented at 2009 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling, November 30th - December 2nd, Paris, France (pp. 87-94).
Open this publication in new window or tab >>Wastegate Actuator Modeling and Model-Based Boost Pressure Control
2009 (English)In: Proceedings of the 2009 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling / [ed] Antonio Sciarretta and Paolino Tona, 2009, p. 87-94Conference paper, Published paper (Refereed)
Abstract [en]

The torque response of an engine is important for driver acceptance. For turbocharged spark ignited (TCSI) engines this is tightly connected to the boost pressure control, which is usually achieved with a wastegate. A challenging scenario is when the throttle is fully open and the load is essentially controlled by the wastegate. First a model for the pneumatic wastegate actuator and air control solenoid is developed. The wastegate model consists of three submodels; the actuator pressure, the static position, and an additional position dynamics. A complete engine model is constructed by including the actuator model in a Mean Value Engine Model (MVEM) for a TCSI engine. This model describes the transient boost pressure response to steps in wastegate control inputs. The subsystems and complete MVEM are validated on an engine test bench and it explains the overshoot seen in the step responses. The model is used to study the system response and give insight into the dominating phenomena and it points out that the engine speed is important for the response. Further, for each speed it is sufficient to model the system as a second order linear system, that captures an overshoot. A controller consisting of a mapped feedforward loop and a gain scheduled feedback loop is developed together with a tuning method based on the IMC framework for the feedback loop. The controller and tuning method is shown to achieve the desired boost pressure behavior both on the complete MVEM and on real engines. The experimental validation is carried out both in an engine test cell and in a vehicle.

Keywords
Engine modeling, engine control, turbocharging, internal model control, PID
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-50769 (URN)10.3182/20091130-3-FR-4008.00012 (DOI)978-3-902661-58-6 (ISBN)
Conference
2009 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling, November 30th - December 2nd, Paris, France
Projects
LINK-SIC, MOVIII
Available from: 2009-10-14 Created: 2009-10-14 Last updated: 2018-01-30Bibliographically approved
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