ACES  Control Avançat de Sistemes d'Energia
http://hdl.handle.net/2117/114
20171019T05:53:12Z

Canonical realization of (2+1)dimensional BondiMetznerSachs symmetry
http://hdl.handle.net/2117/108683
Canonical realization of (2+1)dimensional BondiMetznerSachs symmetry
Batlle Arnau, Carles; Campello, Víctor; Gomis Torné, Joaquin
We construct canonical realizations of the (2+1)dimensional BondiMetznerSachs (bms3) algebra as symmetry algebras of a free KleinGordon (KG) field in 2+1 dimensions for both massive and massless cases. We consider two types of realizations, one on shell, written in terms of the Fourier modes of the scalar field, and the other off shell, with nonlocal transformations written in terms of the KG field and its momenta. These realizations contain both supertranslations and superrotations, for which we construct the corresponding Noether charges.
20171013T11:10:35Z
Batlle Arnau, Carles
Campello, Víctor
Gomis Torné, Joaquin
We construct canonical realizations of the (2+1)dimensional BondiMetznerSachs (bms3) algebra as symmetry algebras of a free KleinGordon (KG) field in 2+1 dimensions for both massive and massless cases. We consider two types of realizations, one on shell, written in terms of the Fourier modes of the scalar field, and the other off shell, with nonlocal transformations written in terms of the KG field and its momenta. These realizations contain both supertranslations and superrotations, for which we construct the corresponding Noether charges.

Nonrelativistic BondiMetznerSachs algebra
http://hdl.handle.net/2117/108665
Nonrelativistic BondiMetznerSachs algebra
Batlle Arnau, Carles; Delmastro, Diego; Gomis Torné, Joaquin
We construct two possible candidates for nonrelativistic bms(4) algebra in four spacetime dimensions by contracting the original relativistic bms(4) algebra. bms(4) algebra is infinitedimensional and it contains the generators of the Poincare algebra, together with the socalled supertranslations. Similarly, the proposed nrbms(4) algebras can be regarded as two infinitedimensional extensions of the Bargmann algebra. We also study a canonical realization of one of these algebras in terms of the Fourier modes of a free Schrodinger field, mimicking the canonical realization of relativistic bms(4) algebra using a free KleinGordon field.
20171011T16:33:50Z
Batlle Arnau, Carles
Delmastro, Diego
Gomis Torné, Joaquin
We construct two possible candidates for nonrelativistic bms(4) algebra in four spacetime dimensions by contracting the original relativistic bms(4) algebra. bms(4) algebra is infinitedimensional and it contains the generators of the Poincare algebra, together with the socalled supertranslations. Similarly, the proposed nrbms(4) algebras can be regarded as two infinitedimensional extensions of the Bargmann algebra. We also study a canonical realization of one of these algebras in terms of the Fourier modes of a free Schrodinger field, mimicking the canonical realization of relativistic bms(4) algebra using a free KleinGordon field.

PMAssisted Synchronous Reluctance Machine flux weakening control for EV and HEV applications
http://hdl.handle.net/2117/108644
PMAssisted Synchronous Reluctance Machine flux weakening control for EV and HEV applications
Trancho, Elena; Ibarra Basabe, Edorta; Arias Pujol, Antoni; Kortabarria, Iñigo; Jurgens, Jonathan; Marengo, Luca; Fricasse, Antonio; Gragger, Johannes
IEEE In this manuscript, a novel robust torque control strategy for Permanent Magnet Assisted Synchronous Reluctance Machine drives applied to electric vehicles and hybrid electric vehicles is presented. Conventional control techniques can highly depend on machine electrical parameters, leading to poor regulation under electrical parameters deviations or, in more serious cases, instabilities. Additionally, machine control can be lost if field weakening is not properly controlled and, as a consequence, uncontrolled regeneration is produced. Thus, advanced control techniques are desirable to guarantee electric vehicle drive controllability in the whole speed/torque operation range and during the whole propulsion system lifetime. In order to achieve these goals, a combination of a robust second order current based Sliding Mode Control and a Look up Table/Voltage Constraint Tracking based hybrid Field Weakening control is proposed, improving the overall control algorithm robustness under parameter deviations. The proposed strategy has been validated experimentally in a full scale automotive test bench (51 kW prototype) for being further implemented in real hybrid and electric vehicles.
20171011T11:22:46Z
Trancho, Elena
Ibarra Basabe, Edorta
Arias Pujol, Antoni
Kortabarria, Iñigo
Jurgens, Jonathan
Marengo, Luca
Fricasse, Antonio
Gragger, Johannes
IEEE In this manuscript, a novel robust torque control strategy for Permanent Magnet Assisted Synchronous Reluctance Machine drives applied to electric vehicles and hybrid electric vehicles is presented. Conventional control techniques can highly depend on machine electrical parameters, leading to poor regulation under electrical parameters deviations or, in more serious cases, instabilities. Additionally, machine control can be lost if field weakening is not properly controlled and, as a consequence, uncontrolled regeneration is produced. Thus, advanced control techniques are desirable to guarantee electric vehicle drive controllability in the whole speed/torque operation range and during the whole propulsion system lifetime. In order to achieve these goals, a combination of a robust second order current based Sliding Mode Control and a Look up Table/Voltage Constraint Tracking based hybrid Field Weakening control is proposed, improving the overall control algorithm robustness under parameter deviations. The proposed strategy has been validated experimentally in a full scale automotive test bench (51 kW prototype) for being further implemented in real hybrid and electric vehicles.

Distributed parameter modelbased control of water activity and concentration of reactants in a polymer electrolyte membrane fuel cell
http://hdl.handle.net/2117/108307
Distributed parameter modelbased control of water activity and concentration of reactants in a polymer electrolyte membrane fuel cell
Sarmiento Carnevali, Maria Laura; Serra, Maria; Batlle Arnau, Carles
Water management is still a key challenge for optimal performance and durability of polymer electrolyte membrane (PEM) fuel cells. Water levels along the channel in a PEM fuel cell present important spatial variations that should be taken into account to avoid both local flooding and local drying. In this work, a decentralised model predictive control scheme is designed to maintain the water activity on both anode and cathode sides of the PEM at appropriate levels. The proposed strategy tackles the accumulation of liquid water on the surface of the catalyst layers, and the possibility of local drying, by controlling observed water activity spatial profiles. Classic PEM fuel cell issues like reactant starvation are also considered. High control performance is achieved. The strategy is applied to a validated distributed parameter PEM fuel cell model. Results show increased cell power density in comparison to nonspatial control strategies.
20171004T07:14:03Z
Sarmiento Carnevali, Maria Laura
Serra, Maria
Batlle Arnau, Carles
Water management is still a key challenge for optimal performance and durability of polymer electrolyte membrane (PEM) fuel cells. Water levels along the channel in a PEM fuel cell present important spatial variations that should be taken into account to avoid both local flooding and local drying. In this work, a decentralised model predictive control scheme is designed to maintain the water activity on both anode and cathode sides of the PEM at appropriate levels. The proposed strategy tackles the accumulation of liquid water on the surface of the catalyst layers, and the possibility of local drying, by controlling observed water activity spatial profiles. Classic PEM fuel cell issues like reactant starvation are also considered. High control performance is achieved. The strategy is applied to a validated distributed parameter PEM fuel cell model. Results show increased cell power density in comparison to nonspatial control strategies.

Energy management strategy for fuel cellsupercapacitor hybrid vehicles based on prediction of energy demand
http://hdl.handle.net/2117/107433
Energy management strategy for fuel cellsupercapacitor hybrid vehicles based on prediction of energy demand
Carignano, Mauro; Costa Castelló, Ramon; Roda Serrat, Vicente; Nigro, Norberto; Junco, Sergio; Feroldi, Diego Hernan
Offering high efficiency and producing zero emissions Fuel Cells (FCs) represent an excellent alternative to internal combustion engines for powering vehicles to alleviate the growing pollution in urban environments. Due to inherent limitations of FCs which lead to slow transient response, FCbased vehicles incorporate an energy storage system to cover the fast power variations. This paper considers a FC/supercapacitor platform that configures a hard constrained powertrain providing an adverse scenario for the energy management strategy (EMS) in terms of fuel economy and drivability. Focusing on palliating this problem, this paper presents a novel EMS based on the estimation of shortterm future energy demand and aiming at maintaining the state of energy of the supercapacitor between two limits, which are computed online. Such limits are designed to prevent active constraint situations of both FC and supercapacitor, avoiding the use of friction brakes and situations of nonpower compliance in a short future horizon. Simulation and experimentation in a case study corresponding to a hybrid electric bus show improvements on hydrogen consumption and power compliance compared to the widely reported Equivalent Consumption Minimization Strategy. Also, the comparison with the optimal strategy via Dynamic Programming shows a room for improvement to the realtime strategies.
20170906T08:59:56Z
Carignano, Mauro
Costa Castelló, Ramon
Roda Serrat, Vicente
Nigro, Norberto
Junco, Sergio
Feroldi, Diego Hernan
Offering high efficiency and producing zero emissions Fuel Cells (FCs) represent an excellent alternative to internal combustion engines for powering vehicles to alleviate the growing pollution in urban environments. Due to inherent limitations of FCs which lead to slow transient response, FCbased vehicles incorporate an energy storage system to cover the fast power variations. This paper considers a FC/supercapacitor platform that configures a hard constrained powertrain providing an adverse scenario for the energy management strategy (EMS) in terms of fuel economy and drivability. Focusing on palliating this problem, this paper presents a novel EMS based on the estimation of shortterm future energy demand and aiming at maintaining the state of energy of the supercapacitor between two limits, which are computed online. Such limits are designed to prevent active constraint situations of both FC and supercapacitor, avoiding the use of friction brakes and situations of nonpower compliance in a short future horizon. Simulation and experimentation in a case study corresponding to a hybrid electric bus show improvements on hydrogen consumption and power compliance compared to the widely reported Equivalent Consumption Minimization Strategy. Also, the comparison with the optimal strategy via Dynamic Programming shows a room for improvement to the realtime strategies.

Observation of the electrochemically active surface area in a proton exchange membrane fuel cell
http://hdl.handle.net/2117/105337
Observation of the electrochemically active surface area in a proton exchange membrane fuel cell
Luna Pacho, Julio Alberto; Usai, Elio; Husar, Attila Peter; Serra, Maria
In this paper a methodology for the estimation of the Electrochemically active Surface Area (ECSA) of a Proton Exchange Membrane Fuel Cell (PEMFC) is developed. Specifically, the ECSA in the Cathode Catalyst Layer (CCL) is estimated, which makes it possible to quantify the amount of active platinum (Pt) in the CCL. In order to estimate the ECSA, the internal conditions of the PEMFC have to be known. A modelbased observer for the distributed parameter dynamics is designed. From the observation of the distributed states, the ECSA can be estimated as well. With the aim of representing the most relevant phenomena that affects the PEMFC voltage, the simulation model includes a twophase water model and the effects of liquid water on the CCL. The results of the methodology are discussed in a simulation environment using the New European Driving Cycle (NEDC) as a case study.
© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
20170612T08:55:15Z
Luna Pacho, Julio Alberto
Usai, Elio
Husar, Attila Peter
Serra, Maria
In this paper a methodology for the estimation of the Electrochemically active Surface Area (ECSA) of a Proton Exchange Membrane Fuel Cell (PEMFC) is developed. Specifically, the ECSA in the Cathode Catalyst Layer (CCL) is estimated, which makes it possible to quantify the amount of active platinum (Pt) in the CCL. In order to estimate the ECSA, the internal conditions of the PEMFC have to be known. A modelbased observer for the distributed parameter dynamics is designed. From the observation of the distributed states, the ECSA can be estimated as well. With the aim of representing the most relevant phenomena that affects the PEMFC voltage, the simulation model includes a twophase water model and the effects of liquid water on the CCL. The results of the methodology are discussed in a simulation environment using the New European Driving Cycle (NEDC) as a case study.

Tachyons in the Galilean limit
http://hdl.handle.net/2117/105012
Tachyons in the Galilean limit
Batlle Arnau, Carles; Gomis Torné, Joaquin; Mezincescu, Luca; Townsend, Paul K.
The Souriau massless Galilean particle of “colour” k and spin s is shown to be the Galilean limit of the Souriau tachyon of mass m = ik and spin s. We compare and contrast this result with the Galilean limit of the NambuGoto string and GreenSchwarz superstring.
20170530T10:09:05Z
Batlle Arnau, Carles
Gomis Torné, Joaquin
Mezincescu, Luca
Townsend, Paul K.
The Souriau massless Galilean particle of “colour” k and spin s is shown to be the Galilean limit of the Souriau tachyon of mass m = ik and spin s. We compare and contrast this result with the Galilean limit of the NambuGoto string and GreenSchwarz superstring.

Nonlinear predictive control for durability enhancement and efficiency improvement in a fuel cell power system
http://hdl.handle.net/2117/104411
Nonlinear predictive control for durability enhancement and efficiency improvement in a fuel cell power system
Luna Pacho, Julio Alberto; Jemei, Samir; YousfiSteiner, Nadia; Husar, Attila Peter; Serra, Maria; Hissel, Daniel
In this work, a nonlinear model predictive control (NMPC) strategy is proposed to improve the efficiency and enhance the durability of a proton exchange membrane fuel cell (PEMFC) power system. The PEMFC controller is based on a distributed parameters model that describes the nonlinear dynamics of the system, considering spatial variations along the gas channels. Parasitic power from different system auxiliaries is considered, including the main parasitic losses which are those of the compressor. A nonlinear observer is implemented, based on the discretised model of the PEMFC, to estimate the internal states. This information is included in the cost function of the controller to enhance the durability of the system by means of avoiding local starvation and inappropriate water vapour concentrations. Simulation results are presented to show the performance of the proposed controller over a given case study in an automotive application (New European Driving Cycle). With the aim of representing the most relevant phenomena that affects the PEMFC voltage, the simulation model includes a twophase water model and the effects of liquid water on the catalyst active area. The control model is a simplified version that does not consider twophase water dynamics.
© <year>. This manuscript version is made available under the CCBYNCND 4.0 license http://creativecommons.org/licenses/byncnd/4.0/
20170515T10:12:22Z
Luna Pacho, Julio Alberto
Jemei, Samir
YousfiSteiner, Nadia
Husar, Attila Peter
Serra, Maria
Hissel, Daniel
In this work, a nonlinear model predictive control (NMPC) strategy is proposed to improve the efficiency and enhance the durability of a proton exchange membrane fuel cell (PEMFC) power system. The PEMFC controller is based on a distributed parameters model that describes the nonlinear dynamics of the system, considering spatial variations along the gas channels. Parasitic power from different system auxiliaries is considered, including the main parasitic losses which are those of the compressor. A nonlinear observer is implemented, based on the discretised model of the PEMFC, to estimate the internal states. This information is included in the cost function of the controller to enhance the durability of the system by means of avoiding local starvation and inappropriate water vapour concentrations. Simulation results are presented to show the performance of the proposed controller over a given case study in an automotive application (New European Driving Cycle). With the aim of representing the most relevant phenomena that affects the PEMFC voltage, the simulation model includes a twophase water model and the effects of liquid water on the catalyst active area. The control model is a simplified version that does not consider twophase water dynamics.

Extended Galilean symmetries of nonrelativistic strings
http://hdl.handle.net/2117/104368
Extended Galilean symmetries of nonrelativistic strings
Batlle Arnau, Carles; Gomis Torné, Joaquin; Not, Daniel
We consider two nonrelativistic strings and their Galilean symmetries. These strings are obtained as the two possible nonrelativistic (NR) limits of a relativistic string. One of them is nonvibrating and represents a continuum of nonrelativistic massless particles, and the other one is a nonrelativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of nonrelativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional spacetime symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of noncentral extensions.
20170512T12:18:09Z
Batlle Arnau, Carles
Gomis Torné, Joaquin
Not, Daniel
We consider two nonrelativistic strings and their Galilean symmetries. These strings are obtained as the two possible nonrelativistic (NR) limits of a relativistic string. One of them is nonvibrating and represents a continuum of nonrelativistic massless particles, and the other one is a nonrelativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of nonrelativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional spacetime symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of noncentral extensions.

Nonlinear model predictive control methodology for efficiency and durability improvement in a fuel cell power system
http://hdl.handle.net/2117/104199
Nonlinear model predictive control methodology for efficiency and durability improvement in a fuel cell power system
Luna Pacho, Julio Alberto; Jemei, Samir; YousfiSteiner, Nadia; Husar, Attila Peter; Serra, Maria
The main contribution of this work is the improvement of the efficiency of a PEMFC power system while guaranteeing conditions that also improve its durability. Adopting the NMPC scheme with the distributed parameter model and the nonlinear observer, the efficiency of the PEMFCbased system can be maximized guaranteeing at the same time the appropriate internal gas concentration profiles to avoid global and local hydrogen and oxygen starvation and proper membrane humidification.
20170508T12:53:55Z
Luna Pacho, Julio Alberto
Jemei, Samir
YousfiSteiner, Nadia
Husar, Attila Peter
Serra, Maria
The main contribution of this work is the improvement of the efficiency of a PEMFC power system while guaranteeing conditions that also improve its durability. Adopting the NMPC scheme with the distributed parameter model and the nonlinear observer, the efficiency of the PEMFCbased system can be maximized guaranteeing at the same time the appropriate internal gas concentration profiles to avoid global and local hydrogen and oxygen starvation and proper membrane humidification.