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  • 1.
    Criscuolo, Ivan
    et al.
    Department of Mechanical Engineering, University of Salerno, Fisciano, Italy.
    Leufvén, Oskar
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Thomasson, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Model-Based Boost Pressure Control with System Voltage Disturbance Rejection2011In: 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 (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.

  • 2.
    Erlingsson, Gissur Ó.
    et al.
    Linköping University, Department for Studies of Social Change and Culture, Centre for Municipality Studies – CKS. Linköping University, Faculty of Arts and Sciences.
    Fogelgren, Mattias
    Linköping University, Department for Studies of Social Change and Culture, Centre for Municipality Studies – CKS. Linköping University, Faculty of Arts and Sciences.
    Olsson, Fredrik
    Institutionen för folkhälsa och vårdvetenskap, Uppsala universitet.
    Thomasson, Anna
    Företagsekonomiska institutionen, Lunds universitet, Ekonomihögskolan.
    Öhrvall, Richard
    Linköping University, Department of Management and Engineering, Political Science. Linköping University, Faculty of Arts and Sciences.
    Hur styrs och granskas kommunala bolag?: Erfarenheter och lärdomar från Norrköpings kommun2014Report (Other academic)
    Abstract [sv]

    Det är vanligt, och blir allt vanligare, att kommuner organiserar sin verksamhet i kommunala bolag. I dagsläget finns omkring 1 700 kommunala bolag (i primärkommunerna). Bolagen spelar en viktig samhällsekonomisk roll. Enligt vissa beräkningar omsätter de ungefär 200 miljarder kronor, sysselsätter omkring 48 000 personer och har ett sammanlagt värde på cirka 1 875 miljarder. Parallellt med att de har vuxit i antal har flera kritiska debatter blossat upp om dem under 2000-talet. Beaktat det samhällsekonomiska perspektivet, samt att bolagens existens motiveras av att de ska ha ett kommunalt ändamål, är rapportens utgångspunkt att det är angeläget att studera frågor som rör styrning och granskning av kommunala bolag.

    Rapportens övergripande syfte är därför att inventera de verktyg för ägarstyrning som en kommun kan nyttja för att säkra att de kommunala bolagen verkligen gör det de är avsedda att göra. Det är en pilotstudie, oss veterligen den första i sitt slag. Eftersom vi saknar jämförbara data från andra kommuner att ställa våra resultat mot har vi heller ingen möjlighet att säga huruvida det vi finner ska betraktas som ”bra” eller ”mindre bra”. Det är heller inte vår avsikt. Ambitionen är istället att bidra till ökad reflektion kring hur kommuner kan bli bättre som bolagsägare. Med stöd i våra resultat redovisas slutsatserna i form av sex diskussionspunkter. De har en generell prägel och torde ha relevans för alla kommuner som äger bolag.

    • Fullmäktigeledamöter efterlyser ett levande samtal om bolagen. Vår undersökning visar att överraskande många fullmäktigeledamöter anser att bolagen inte diskuteras i tillräckligt stor utsträckning i kommunfullmäktige. Hit hör också att ungefär hälften av fullmäktigeledamöterna (som saknar styrelseuppdrag) som besvarade vår enkät uttrycker missnöje med hur lekmannarevisorernas granskning av bolagen återrapporteras till fullmäktige. Från fullmäktigeledamöternas sida finns sålunda en önskan om att bolagen diskuteras i större utsträckning i kommunfullmäktige liksom att lekmannarevisorernas rapporter lyfts fram på ett bättre sätt i fullmäktige.
    • Det finns en viss opinion för att reformera dagens bolagsstruktur. Flera av dem som besvarade vår enkät anser det vara olämpligt att driva verksamheter inom ”kultur, fritid, turism och event” samt ”kommunikationer, transport och magasinering”. Kritisk diskussion om existensberättigandet för vissa bolag förekom också i våra intervjuer. Hit hör också att en minoritet av dem som besvarade enkäten anser att dagens bolagsstruktur är tydlig och genomskådlig. Siffran betraktar vi som låg mot bakgrund av att kommunfullmäktige bär det yttersta ansvaret för kommunernas bolagsstyrning. Dessa sakförhållanden aktualiserar frågan om kommunen borde initiera en samlad diskussion om hur optimal dagens bolagsstruktur egentligen är.
    • Det finns frågetecken om arkivering, dokumentation och öppenhet. Den upplevda bristen på transparens i bolagsstrukturen tangerar frågor om insyn och ansvarsutkrävande. En förutsättning för kritisk medborgerlig, forskningsmässig eller journalistisk granskning av offentligt utförda verksamheter (och därmed för ansvarsutkrävande) är att det är någorlunda enkelt att granska bolagen. Här finns utvecklingsområden. I vår enkät svarade cirka hälften av fullmäktigeledamöterna (utan styrelseuppdrag) att de helt enkelt inte vet om det är lätt eller svårt att få ut information om de kommunala bolagen. Dessutom angav en majoritet av de svarande att de tror att insyn och granskning blir svårare när verksamhet bedrivs i bolagsform. Också värt att uppmärksamma är att bara drygt hälften av styrelseledamöterna uppgav att de kände till de etiska riktlinjerna för de kommunala bolag i vars styrelse de sitter. Det är en anmärkningsvärd siffra då styrelserna själva ansvarar för att dessa riktlinjer ska vara på plats. Vad avser upprättande av och kännedom om exempelvis etiska riktlinjer förefaller en del arbete återstå i ett par av bolagen.
    • Enligt politiker och styrelseledamöter fungerar lekmannarevisionen bra, men man efterlyser en bättre diskussion av revisorernas granskningar i fullmäktige. Vår enkätstudie, liksom våra intervjuer med lekmannarevisorer, ger vid handen att lekmannarevisionen i Norrköpingfungerar tillfredsställande. Åtta av tio ansåg den fungera mycket eller ganska väl, och lekmannarevisorerna säger sig uppleva en stigande respekt för det arbete de utför. Ett utvecklingsområde som vi noterar imaterialet är att såväl fullmäktigeledamöterna som de intervjuade  lekmannarevisorerna tycker att bolagen och revisorernas granskningar diskuteras i för liten utsträckning i fullmäktige. Med tanke på att båda aktörerna delar denna problembeskrivning torde detta vara förhållandevis lätt att åtgärda.
    • Arbetet med att utse styrelser kan stärkas och bli mer transparent; utbildning och kompetensutveckling för styrelserna kan vässas. I enkätstudien spårar vi ett visst missnöje med processen genom vilken styrelseledamöter i Norrköpings kommunala bolag tillsätts. Bland fullmäktigeledamöter som saknar styrelseuppdrag menar bara drygt hälften att processen är genomskinlig och en tredjedel anser att befintliga processer inte säkrar att lämpliga styrelseledamöter ta  fram. En anmärkningsvärt låg andel, 15 procent, menar att det rådande sättet på vilket styrelseledamöter tas fram till stor del säkerställer att lämpliga kandidater utses till bolagsstyrelser. I materialet reses också frågetecken kring vilka utbildningsinsatser som erbjuds för styrelseledamöter. Avseende utbildningar för styrelseledamöter förefaller det finnas utrymme för förbättringar genom bättre struktur och systematik avseende frågor som när utbildningarna ska ges, vem som ska ansvara för att de ges och vad utbildningarna ska innehålla.
    • ”Personunion”: ett principiellt dilemma. I likhet med de flesta av landets kommuner finns i Norrköping en koncentration av uppdrag till ett mindre antal av kommunens ledande politiker. Vissa ser klara fördelar med ett sådant system. Styrningen blir mer praktisk och effektiv: de som sitter på flera stolar är redan insatta i kommunens organisation och i de aktuella frågorna, vilket gör att det blir lättare att hålla samman den interna styrningen då kommunikationen mellan tunga beslutsfattare underlättas. Samtidigt reser ordningen frågor, främst för att den ger upphov till en ”dubbla stolar”-problematik som kan bidra till försvårad insyn och kontroll, och därmed också besvärligare ansvarsutkrävande. Till ”dubbla stolar”-problematiken hör också följande. I fallet Norrköping sitter en av fyra styrelseledamöter även i kommunfullmäktige; och dessutom sitter flera kommunstyrelseledamöter i moderbolagets (Rådhus AB) styrelse. På papperet är det inte givet att rollerna är förenliga. Kommunfullmäktige har det yttersta ansvaret över kommunens bolagsstyrning och vidare har kommunstyrelsen sedan 2013 förstärkt uppsiktsplikt över bolagen. Det innebär att fullmäktige- och kommunstyrelseledamöter har en ägarrelation till bolagen. Så, för de fullmäktige- och kommunstyrelseledamöter som sitter i kommunala bolagsstyrelser innebär läget en potentiell lojalitetskonflikt: förutom att ha ägaransvar och uppsiktplikt, förväntas de agera utifrån bolagets perspektiv och se till bolagens bästa. Sedan en rapport från kommunrevisionen publicerades år 2012 finns det emellertid en diskussion om dessa frågor som signalerar medvetenhet om personunionens inneboende dilemman. Ett arbete pågår med att formalisera styrningen och uppföljningen av de kommunala bolagen i Norrköpings kommun.
  • 3.
    Thomasson, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Modeling and control of actuators and co-surge in turbocharged engines2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The torque response of the engine is important for the driving experience of a vehicle. In spark ignited engines, torque is proportional to the air flow into the cylinders. Controlling torque therefore implies controlling air flow. In modern turbocharged engines, the driver commands are interpreted by an electronic control unit that controls the engine through electromechanical and pneumatic actuators. Air flow to the intake manifold is controlled by an electronic throttle, and a wastegate controls the energy to the turbine, affecting boost pressure and air flow. These actuators and their dynamics affect the torque response and a lot of time is put into calibration of controllers for these actuators. By modeling and understanding the actuator behavior this dynamics can be compensated for, leaving a reduced control problem, which can shorten the calibration time.

    Electronic throttle servo control is the first problem studied. By constructing a control oriented model for the throttle servo and inverting that model, the resulting controller becomes two static compensators for friction and limp-home nonlinearities, together with a PD-controller. A gain-scheduled I-part is added for robustness to handle model errors. The sensitivity to model errors is studied and a method for tuning the controller is presented. The performance has been evaluated in simulation, in test vehicle, and in a throttle control benchmark.

    A model for a pneumatic wastegate actuator and solenoid control valve, used for boost pressure control, is presented. The actuator dynamics is shown to be important for the transient boost pressure response. The model is incorporated in a mean value engine model and shown to give accurate description of the transient response. A tuning method for the  feedback (PID) part of a boost controller is proposed, based on step responses in wastegate control signal. Together with static feedforward the controller is shown to achieve the desired boost pressure response. Submodels for an advanced boost control system consisting of several vacuum actuators, solenoid valves, a vacuum tank and a vacuum pump are developed. The submodels and integrated system are evaluated on a two stage series sequential turbo system, and control with system voltage disturbance rejection is demonstrated on an engine in a test cell.

    Turbocharged V-type engines often have two parallel turbochargers, each powered by one bank of cylinders. When the two air paths are connected before the throttle an unwanted oscillation can occur. When the compressors operate close to the surge line and a disturbance alters the mass flow balance, the compressors can begin to alternately go into surge, this is called co-surge. Measurements on co-surge in parallel turbocharged engines are presented and analyzed. A mean value engine model, augmented with a Moore-Greitzer compressor model to handle surge, is shown to capture the cosurge behavior. A sensitivity analysis shows which model parameters have the largest influence of the phenomena. The compressor operation in the map during co-surge is studied, and the alternating compressor speeds are shown to have a major impact on the continuing oscillation. Based on the analysis, detection methods and a controller are proposed, these detect co-surge and control the turbo speeds to match during co-surge. The controller is evaluated both in simulation and on a test vehicle in a vehicle dynamometer, showing that co-surge can be detected and the oscillations quelled.

    List of papers
    1. Model-Based Throttle Control using Static Compensators and Pole Placement
    Open this publication in new window or tab >>Model-Based Throttle Control using Static Compensators and Pole Placement
    2011 (English)In: Oil & gas science and technology, ISSN 1294-4475, E-ISSN 1953-8189, Vol. 66, no 4, p. 717-727Article in journal (Refereed) Published
    Abstract [en]

    Model-Based Throttle Control using Static Compensators and Pole Placement - In modern spark ignited engines, the throttle is controlled by the Electronic Control Unit (ECU), which gives the ECU direct control of the air flow and thereby the engine torque. This puts high demands on the speed and accuracy of the controller that positions the throttle plate. The throttle control problem is complicated by two strong nonlinear effects, friction and limp-home torque. This paper proposes the use of two, simultaneously active, static compensators to counter these effects and approximately linearize the system. A PID controller is designed for the linearized system, where pole placement is applied to design the PD controller and a gain scheduled I-part is added for robustness against model errors. A systematic procedure for generating compensator and controller parameters from open loop experiments is also developed. The controller performance is evaluated both in simulation, on a throttle control benchmark problem, and experimentally. A robustness investigation pointed out that the limp-home position is an important parameter for the controller performance, this is emphasized by the deviations found in experiments. The proposed method for parameter identification achieves the desired accuracy.

    Place, publisher, year, edition, pages
    Institut Francais du Petrole, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73743 (URN)10.2516/ogst/2011137 (DOI)000297969200015 ()
    Available from: 2012-01-12 Created: 2012-01-12 Last updated: 2018-01-30
    2. Wastegate Actuator Modeling and Model-Based Boost Pressure Control
    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
    3. Modeling and validation of a boost pressure actuation system, for a series sequentially turbocharged SI engine
    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
    4. Modeling and Control of Co-Surge in Bi-Turbo Engines
    Open this publication in new window or tab >>Modeling and Control of Co-Surge in Bi-Turbo Engines
    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. 13010-13015Conference paper, Published paper (Refereed)
    Abstract [en]

    Using a bi-turbocharged configuration makes for better utilization of the exhaust energy and a faster torque response in V-type engines. A special surge phenomenon that should be avoided in bi-turbocharged engines is co-surge, which is when the two interconnected compressors alternately go into flow reversals. If co-surge should occur, the control system must be able to quell the oscillations with as little disturbance in torque as possible. This paper presents a model of a bi-turbocharged engine based on a Mean Value Engine Model that includes a More-Greizer compressor model for surge. The model is validated against measured data showing that it captures the frequency and amplitude of the co-surge oscillation. The effect of momentum conservation in the pipes is investigated by adding this feature to the control volumes before and after the compressor. This gives a slightly better mass flow shape with the drawback of increased simulation time, due to more states and a higher frequency content in the model. A sensitivity analysis is performed to investigate which model parameters have most influence on the co-surge behavior. It is shown that the largest influence comes from the turbocharger inertia, the volumes after the compressor and the ``zero mass flow pressure ratio'' during flow reversal in the compressor. The model is used to investigate principles for control strategies to detect and quell co-surge. The detection algorithm is evaluated on measured data.

    Place, publisher, year, edition, pages
    International Federation of Automatic Control (IFAC), 2011
    Keywords
    Modeling, supervision, control and diagnosis of automotive systems, Automotive system identification and modelling
    National Category
    Vehicle Engineering
    Identifiers
    urn:nbn:se:liu:diva-90922 (URN)10.3182/20110828-6-IT-1002.02338 (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: 2013-04-09 Last updated: 2018-01-30Bibliographically approved
    5. Co-Surge in Bi-Turbo Engines: Measurements, Analysis and Control
    Open this publication in new window or tab >>Co-Surge in Bi-Turbo Engines: Measurements, Analysis and Control
    2014 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 32, p. 113-122Article in journal (Refereed) Published
    Abstract [en]

    In parallel turbocharged V-engines, with two separate air paths connected before the throttle, an oscillation in the flow can occur.If the compressor operates close to the surge line, typically during low speed and high load, and a disturbance alters the massflow balance, the compressors can begin to alternately go into surge. This phenomenon is called co-surge and is unwanted due tohigh noise and risk for turbocharger destruction. Co-surge is measured on a test vehicle in a chassis dynamometer and the systemanalyzed and modeled using a mean value engine model. The investigation shows that the alternating compressor speeds have animportant role in the prolonged oscillation. A reconstruction of the negative flow from measurements is made and compared tosimulation results, showing similar amplitudes, and supports the model validation. A new co-surge detection algorithm is presented,suitable for a pair of sensors measuring either mass flow, boost pressure or turbo speed in the two air paths. Furthermore, a newcontroller is proposed that uses a model based feedforward for the throttle, together with wastegate actuation to force the compressorspeeds together and improve balance at the recovery point. This has shown to be sufficient with moderate to high pressure ratiosover the throttle, only for zero or very low pressure drop the use of bypass valves are necessary. The advantage of not opening thebypass valves is a smaller drop in boost pressure which also reduces the torque disturbance. The performance of the controller is evaluated both in simulation and in the test vehicle.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Compressor surge, surge detection, surge control, engine modeling, engine control
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-105686 (URN)10.1016/j.conengprac.2014.08.001 (DOI)000344435200009 ()
    Available from: 2014-04-02 Created: 2014-04-02 Last updated: 2018-01-30Bibliographically approved
  • 4.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Co-Surge Detection and Control for Bi-Turbo Engines with Experimental Evaluation2013Conference paper (Refereed)
    Abstract [en]

    A V-type engine with a bi-turbocharger configuration utilizes the exhaust energy well which gives a fast torque response. An unwanted instability, called co-surge, can occur in such engines where the two interconnected compressors alternately go into flow reversals. If co-surge occurs, the control system must quell the oscillations with as little disturbance in engine torque as possible. A model of a bi-turbocharged engine is presented, combining a mean value engine model and a Moore-Greizer compressor model for surge. The model is validated against measurements on a vehicle dynamometer, showing that it captures the frequency and amplitude of the co-surge oscillation. The model is used to develop detection and control strategies for co-surge that rapidly returns the turbo to a stable operating point. Both simulations and experimental evaluation on the vehicle show that the developed strategies are successful in rapidly detecting and quelling co-surge. The selection of actuators is also studied. With no or small pressure drops over the throttle, it is necessary to use the bypass valves. However, for operating conditions with moderate and high pressure drops over the throttle, it is shown that it is sufficient to only open the throttle. This has the advantage, compared to opening the bypass valves, that it reduces the drop in boost pressure and thus reduces the drop in engine torque.

  • 5.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Co-Surge in Bi-Turbo Engines: Measurements, Analysis and Control2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 32, p. 113-122Article in journal (Refereed)
    Abstract [en]

    In parallel turbocharged V-engines, with two separate air paths connected before the throttle, an oscillation in the flow can occur.If the compressor operates close to the surge line, typically during low speed and high load, and a disturbance alters the massflow balance, the compressors can begin to alternately go into surge. This phenomenon is called co-surge and is unwanted due tohigh noise and risk for turbocharger destruction. Co-surge is measured on a test vehicle in a chassis dynamometer and the systemanalyzed and modeled using a mean value engine model. The investigation shows that the alternating compressor speeds have animportant role in the prolonged oscillation. A reconstruction of the negative flow from measurements is made and compared tosimulation results, showing similar amplitudes, and supports the model validation. A new co-surge detection algorithm is presented,suitable for a pair of sensors measuring either mass flow, boost pressure or turbo speed in the two air paths. Furthermore, a newcontroller is proposed that uses a model based feedforward for the throttle, together with wastegate actuation to force the compressorspeeds together and improve balance at the recovery point. This has shown to be sufficient with moderate to high pressure ratiosover the throttle, only for zero or very low pressure drop the use of bypass valves are necessary. The advantage of not opening thebypass valves is a smaller drop in boost pressure which also reduces the torque disturbance. The performance of the controller is evaluated both in simulation and in the test vehicle.

  • 6.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Effects of Pulsating Flow on Mass Flow Balance and Surge Margin in Parallel Turbocharged Engines2015In: Proceedings of the 56th Conference on Simulation and Modelling (SIMS 56), October, 7-9, 2015, Linköping University, Sweden, Linköping: Linköping University Electronic Press, 2015, Vol. 119, p. 15-20Conference paper (Refereed)
    Abstract [en]

    The paper extends a mean value model of a parallel turbocharged internal combustion engine with a crank angle resolved cylinder model. The result is a 0D engine model that includes the pulsating flow from the intake and exhaust valves. The model captures variations in turbo speed and pressure, and therefore variations in the compressor operating point, during an engine cycle. The model is used to study the effect of the pulsating flow on mass flow balance and surge margin in parallel turbocharged engines, where two compressors are connected to a common intake manifold. This configuration is harder to control compared to single turbocharged systems, since the compressors interact and can work against each other, resulting in co-surge. Even with equal average compressor speed and flow, the engine pulsations introduce an oscillation in the turbo speeds and mass flow over the engine cycle. This simulation study use the developed model to investigates how the engine pulsations effect the in cycle variation in compressor operating point and the sensitivity to co-surge. It also shows how a short circuit pipe between the two exhaust manifolds could increase surge margin at the expense of less available turbine energy.

  • 7.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Model-Based Throttle Control using Static Compensators and Pole Placement2011In: Oil & gas science and technology, ISSN 1294-4475, E-ISSN 1953-8189, Vol. 66, no 4, p. 717-727Article in journal (Refereed)
    Abstract [en]

    Model-Based Throttle Control using Static Compensators and Pole Placement - In modern spark ignited engines, the throttle is controlled by the Electronic Control Unit (ECU), which gives the ECU direct control of the air flow and thereby the engine torque. This puts high demands on the speed and accuracy of the controller that positions the throttle plate. The throttle control problem is complicated by two strong nonlinear effects, friction and limp-home torque. This paper proposes the use of two, simultaneously active, static compensators to counter these effects and approximately linearize the system. A PID controller is designed for the linearized system, where pole placement is applied to design the PD controller and a gain scheduled I-part is added for robustness against model errors. A systematic procedure for generating compensator and controller parameters from open loop experiments is also developed. The controller performance is evaluated both in simulation, on a throttle control benchmark problem, and experimentally. A robustness investigation pointed out that the limp-home position is an important parameter for the controller performance, this is emphasized by the deviations found in experiments. The proposed method for parameter identification achieves the desired accuracy.

  • 8.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Model-Based Throttle Control using StaticCompensators and IMC based PID-Design2009In: 2009 IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling. Paris, France., 2009Conference paper (Refereed)
    Abstract [en]

    In modern spark ignited engines the throttle is controlled by the electronic control unit (ECU) which gives the ECU direct control of the air flow and thereby the engine torque. This puts high demands on the speed and accuracy of the controller that positions the throttle plate. The throttle control problem is complicated by two strong nonlinear effects, friction and limp-home torque. This paper proposes the use of two, simultaneously active, static compensators to counter these effects and approximately linearize the system. A PID controller is designed for the linearized system, where IMC design is applied to design the PD controller and a gain scheduled I-part is added for robustness against model errors. A systematic procedure for generating compensator and controller parameters from open loop experiments is also developed. The controller performance is evaluated both in simulation, on a TC-benchmark problem, and experimentally. A robustness investigation pointed out that the limp-home position is an important parameter for the controller performance, this is emphasized by the deviations found in experiments. The proposed method for parameter identification achieves the desired accuracy.

  • 9.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Modeling and Control of Co-Surge in Bi-Turbo Engines2011In: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, p. 13010-13015Conference paper (Refereed)
    Abstract [en]

    Using a bi-turbocharged configuration makes for better utilization of the exhaust energy and a faster torque response in V-type engines. A special surge phenomenon that should be avoided in bi-turbocharged engines is co-surge, which is when the two interconnected compressors alternately go into flow reversals. If co-surge should occur, the control system must be able to quell the oscillations with as little disturbance in torque as possible. This paper presents a model of a bi-turbocharged engine based on a Mean Value Engine Model that includes a More-Greizer compressor model for surge. The model is validated against measured data showing that it captures the frequency and amplitude of the co-surge oscillation. The effect of momentum conservation in the pipes is investigated by adding this feature to the control volumes before and after the compressor. This gives a slightly better mass flow shape with the drawback of increased simulation time, due to more states and a higher frequency content in the model. A sensitivity analysis is performed to investigate which model parameters have most influence on the co-surge behavior. It is shown that the largest influence comes from the turbocharger inertia, the volumes after the compressor and the ``zero mass flow pressure ratio'' during flow reversal in the compressor. The model is used to investigate principles for control strategies to detect and quell co-surge. The detection algorithm is evaluated on measured data.

  • 10.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Leufvén, Oskar
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Andersson, Per
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Wastegate Actuator Modeling and Model-Based Boost Pressure Control2009In: 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 (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.

  • 11.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Lindell, Tobias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Peyton Jones, James C.
    Villanova University, PA, USA.
    Spelina, Jill
    Villanova University, PA, USA.
    Frey, Jesse
    Villanova University, PA, USA.
    Tuning and experimental evaluation of a likelihood-based engine knock controller2013In: Proceedings of the 52nd IEEE Conference on Decision & Control, IEEE conference proceedings, 2013, p. 6849-6854Conference paper (Refereed)
    Abstract [en]

    A new likelihood-based stochastic knock controller, that achieves a significantly improved regulatory response relative to conventional strategies, while also maintaining a rapid transient response is presented. Up until now it has only been evaluated using simulations and the main contribution here is the implementation and validation of the knock controller on a five cylinder engine with variable compression ratio. Furthermore, an extension of the fast response strategy and a re-tuning of the controller is shown to improve performance. The controller is validated with respect to its robustness to changes in engine operating condition as well as compression ratio. The likelihood-based controller is demonstrated in engine tests and compared to a conventional controller and it is shown that it is able to operate closer to the knock limit with less variations in control action without increasing the risk of engine damage.

  • 12.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Leufvén, Oskar
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Criscuolo, Ivan
    University of Salerno, Italy .
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Modeling and validation of a boost pressure actuation system, for a series sequentially turbocharged SI engine2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 12, p. 1860-1870Article in journal (Refereed)
    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.

  • 13.
    Thomasson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Shi, Haoyun
    Sophia University, Japan.
    Lindell, Tobias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Shen, Tielong
    Sophia University, Japan.
    Peyton Jones, James C.
    Villanova University, PA 19085 USA.
    Experimental Validation of a Likelihood-Based Stochastic Knock Controller2016In: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 24, no 4, p. 1407-1418Article in journal (Refereed)
    Abstract [en]

    New likelihood-based stochastic knock controllers have the potential to deliver a significantly improved regulatory response relative to conventional strategies, while also maintaining a rapid transient response, but evaluation studies to date have been performed only in simulation. In this paper, an experimental validation of the new strategy is presented. To demonstrate the robustness of the method, the algorithm is implemented on two different engine platforms, using two different knock intensity metrics, and evaluated under different operating conditions. One of these platforms is a five-cylinder variable compression ratio engine, enabling the controller to be tested under different compression ratios, as well as different speed and load conditions. The regulatory and transient performance of the likelihood-based controller is assessed in a back-to-back comparison with a conventional knock controller and it is shown that the new controller is able to operate closer to the knock limit with less variation in control action without increasing the risk of engine damage.

1 - 13 of 13
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