ACES  Control Avançat de Sistemes d'Energia
http://hdl.handle.net/2117/114
20170122T18:35:44Z

Resonance damping of LCL filters via input admittance frequency shaping
http://hdl.handle.net/2117/99571
Resonance damping of LCL filters via input admittance frequency shaping
Perez Morales, Jorge; Cóbreces Álvarez, Santiago; Pizarro, Daniel; Rodriguez Sanchez, Francisco Javier; Griñó Cubero, Robert
This paper presents a novel active damping technique of currentcontrolled gridconnected power converters through LCL filters. Based on H8 synthesis algorithms, a grid current controller is obtained so that the gridconnected power convertedbased application admittance resembles a given frequency reference. By defining a low resistive admittance as the reference, considered application resonance is effectively damped, reducing grid current oscillations under grid voltage variations and avoiding their associated stability problems. Presented grid current controller senses only the PCC grid voltage and current, and is experimentally tested in both time and frequency domains. Additionally, the effectiveness of presented damping method is proved under different grid impedance scenarios.
© 2016 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
20170118T10:41:03Z
Perez Morales, Jorge
Cóbreces Álvarez, Santiago
Pizarro, Daniel
Rodriguez Sanchez, Francisco Javier
Griñó Cubero, Robert
This paper presents a novel active damping technique of currentcontrolled gridconnected power converters through LCL filters. Based on H8 synthesis algorithms, a grid current controller is obtained so that the gridconnected power convertedbased application admittance resembles a given frequency reference. By defining a low resistive admittance as the reference, considered application resonance is effectively damped, reducing grid current oscillations under grid voltage variations and avoiding their associated stability problems. Presented grid current controller senses only the PCC grid voltage and current, and is experimentally tested in both time and frequency domains. Additionally, the effectiveness of presented damping method is proved under different grid impedance scenarios.

On existence and stability of equilibria of dc LTI circuits with constant power loads
http://hdl.handle.net/2117/99569
On existence and stability of equilibria of dc LTI circuits with constant power loads
Barabanov, Nikita; Ortega, Romeo; Griñó Cubero, Robert; Polyak, Boris
This paper studies the problem of existence and stability of equilibria of dc linear time–invariant circuits with constant power loads. First, we correct an unfortunate mistake in our previous work [10] pertaining to the sufficiency of the condition for existence of equilibria in multiport systems given there. Second, we give two necessary conditions for existence
of equilibria. The first one is a simple linear matrix inequality hence it can be easily verified with existing software. Third, we prove that the latter condition is also sufficient if a set defined by the problem data is convex, which is the case for single and two–port systems. Finally, sufficient conditions for stability and instability for a given equilibrium point are given. The results are illustrated with two benchmark examples
© 2016 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
20170118T10:27:44Z
Barabanov, Nikita
Ortega, Romeo
Griñó Cubero, Robert
Polyak, Boris
This paper studies the problem of existence and stability of equilibria of dc linear time–invariant circuits with constant power loads. First, we correct an unfortunate mistake in our previous work [10] pertaining to the sufficiency of the condition for existence of equilibria in multiport systems given there. Second, we give two necessary conditions for existence
of equilibria. The first one is a simple linear matrix inequality hence it can be easily verified with existing software. Third, we prove that the latter condition is also sufficient if a set defined by the problem data is convex, which is the case for single and two–port systems. Finally, sufficient conditions for stability and instability for a given equilibrium point are given. The results are illustrated with two benchmark examples

Switching frequency regulation in sliding mode control by a hysteresis band controller
http://hdl.handle.net/2117/99560
Switching frequency regulation in sliding mode control by a hysteresis band controller
Repecho del Corral, Víctor; Biel Solé, Domingo; Olm Miras, Josep Maria; Fossas Colet, Enric
Fixing the switching frequency is a key issue in sliding mode control implementations. This paper presents a hysteresis band controller capable of setting a constant value for the steadystate switching frequency of a sliding mode controller in regulation and tracking tasks. The proposed architecture relies on a piecewise linear modeling of the switching function behavior within the hysteresis band, and consists of a discretetime integraltype controller that modifies the amplitude of the hysteresis band of the comparator in accordance with the error between the desired and the actually measured switching period. For tracking purposes, an additional feedforward action is introduced to compensate the time variation of the switching function derivatives at either sides of the switching hyperplane in the steady state. Stability proofs are provided, and a design criterion for the control parameters to guarantee closedloop stability is subsequently derived. Numerical simulations and experimental results validate the proposal.
© 2016 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
20170118T07:35:30Z
Repecho del Corral, Víctor
Biel Solé, Domingo
Olm Miras, Josep Maria
Fossas Colet, Enric
Fixing the switching frequency is a key issue in sliding mode control implementations. This paper presents a hysteresis band controller capable of setting a constant value for the steadystate switching frequency of a sliding mode controller in regulation and tracking tasks. The proposed architecture relies on a piecewise linear modeling of the switching function behavior within the hysteresis band, and consists of a discretetime integraltype controller that modifies the amplitude of the hysteresis band of the comparator in accordance with the error between the desired and the actually measured switching period. For tracking purposes, an additional feedforward action is introduced to compensate the time variation of the switching function derivatives at either sides of the switching hyperplane in the steady state. Stability proofs are provided, and a design criterion for the control parameters to guarantee closedloop stability is subsequently derived. Numerical simulations and experimental results validate the proposal.

Hysteretic control of gridside current for a singlephase LCL gridconnected voltage source converter
http://hdl.handle.net/2117/99434
Hysteretic control of gridside current for a singlephase LCL gridconnected voltage source converter
Cóbreces Álvarez, Santiago; Griñó Cubero, Robert
This paper proposes a new approach to control the gridside current of LCLgrid connected voltage source converters using hysteretic relay feedback controllers. The closed loop system is stabilized by designing a local feedback around the relay element. The compensator allows the use of relay feedback controllers by making the controlled plant almost strictly positive real. The article proposes the use of the locus of the perturbed relay system as analysis and design tool and studies orbital stability for several plant and controller conditions. The approach is validated by means of simulation testing.
© 2016. This manuscript version is made available under the CCBYNCND 4.0 license http://creativecommons.org/licenses/byncnd/4.0/
20170117T11:28:04Z
Cóbreces Álvarez, Santiago
Griñó Cubero, Robert
This paper proposes a new approach to control the gridside current of LCLgrid connected voltage source converters using hysteretic relay feedback controllers. The closed loop system is stabilized by designing a local feedback around the relay element. The compensator allows the use of relay feedback controllers by making the controlled plant almost strictly positive real. The article proposes the use of the locus of the perturbed relay system as analysis and design tool and studies orbital stability for several plant and controller conditions. The approach is validated by means of simulation testing.

Modelbased analysis for the thermal management of opencathode proton exchange membrane fuel cell systems concerning efficiency and stability
http://hdl.handle.net/2117/97751
Modelbased analysis for the thermal management of opencathode proton exchange membrane fuel cell systems concerning efficiency and stability
Costa Castelló, Ramon; Strahl, Stephan
In this work we present a dynamic, controloriented, concentrated parameter model of an opencathode proton exchange membrane fuel cell system for the study of stability and efficiency improvement with respect to thermal management. The system model consists of two dynamic states which are the fuel cell temperature and the liquid water saturation in the cathode catalyst layer. The control action of the system is the inlet air velocity of the cathode air flow manifold, set by the cooling fan, and the system output is the stack voltage. From the model we derive the equilibrium points and eigenvalues within a set of operating conditions and subsequently discuss stability and the possibility of efficiency improvement. The model confirms the existence of a temperaturedependent maximum power in the moderate temperature region. The stability analysis shows that the maximum power line decomposes the phase plane in two parts, namely stable and unstable equilibrium points. The model is capable of predicting the temperature of a stable steadystate voltage maximum and the simulation results serve for the design of optimal thermal management strategies.
20161205T10:00:52Z
Costa Castelló, Ramon
Strahl, Stephan
In this work we present a dynamic, controloriented, concentrated parameter model of an opencathode proton exchange membrane fuel cell system for the study of stability and efficiency improvement with respect to thermal management. The system model consists of two dynamic states which are the fuel cell temperature and the liquid water saturation in the cathode catalyst layer. The control action of the system is the inlet air velocity of the cathode air flow manifold, set by the cooling fan, and the system output is the stack voltage. From the model we derive the equilibrium points and eigenvalues within a set of operating conditions and subsequently discuss stability and the possibility of efficiency improvement. The model confirms the existence of a temperaturedependent maximum power in the moderate temperature region. The stability analysis shows that the maximum power line decomposes the phase plane in two parts, namely stable and unstable equilibrium points. The model is capable of predicting the temperature of a stable steadystate voltage maximum and the simulation results serve for the design of optimal thermal management strategies.

On teaching modelbased fault diagnosis in engineering curricula
http://hdl.handle.net/2117/97749
On teaching modelbased fault diagnosis in engineering curricula
Costa Castelló, Ramon; Puig Cayuela, Vicenç; Blesa Izquierdo, Joaquim
This article presents an example of how a faultdiagnosis course has been included in an engineering curricula in a motivating way, in particular, in the automatic control and robotic master's degree program at UPC. This article also shows how a PBL methodology has been used in the lab sessions to introduce students to modelbased fault diagnosis. With this methodology, a realworld problem is used to increase students' interest and at the same time help them to acquire and apply new knowledge in a problemsolving context. Observerand parityequationsbased methods for fault detection and structured residuals for fault isolation are introduced to the students from a practical point of view by lab exercises. The course also motivates the interest in fault diagnosis as a first step toward the design of a faulttolerant control system. Assessment results and student surveys carried out before and after the application of the PBL methodology confirm the increase of interest and fulfillment of the SLOs.
© 2016 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
20161205T09:43:23Z
Costa Castelló, Ramon
Puig Cayuela, Vicenç
Blesa Izquierdo, Joaquim
This article presents an example of how a faultdiagnosis course has been included in an engineering curricula in a motivating way, in particular, in the automatic control and robotic master's degree program at UPC. This article also shows how a PBL methodology has been used in the lab sessions to introduce students to modelbased fault diagnosis. With this methodology, a realworld problem is used to increase students' interest and at the same time help them to acquire and apply new knowledge in a problemsolving context. Observerand parityequationsbased methods for fault detection and structured residuals for fault isolation are introduced to the students from a practical point of view by lab exercises. The course also motivates the interest in fault diagnosis as a first step toward the design of a faulttolerant control system. Assessment results and student surveys carried out before and after the application of the PBL methodology confirm the increase of interest and fulfillment of the SLOs.

An interactivitybased methodology to support control education. How to teach and learn using simple interactive tools.
http://hdl.handle.net/2117/97748
An interactivitybased methodology to support control education. How to teach and learn using simple interactive tools.
Guzmán Sánchez, José Luis; Costa Castelló, Ramon; Dormido Bencomo, Sebastián; Berenguel, Miguel
Modern engineering projects are multidisciplinary and involve the integration of diverse elements. Within this context, automatic control plays a crucial role. Automatic control is an area of knowledge with significant mathematical content, including differential equations, linear algebra, differential geometry, and/or complex variable among others. Consequently, in many cases, automatic control is difficult for most students to grasp, especially in those cases where students have only an introductory control course in their engineering curriculum. Thus, teachers look for ways to introduce and make automatic control attractive for the students. From the very beginning, graphical representation has been used as support in automatic control teaching. Looking back to the pioneering books in automatic control, it can be seen that there are plenty of schematics and figures. Graphical abstraction was also used to contribute to theoretical understanding. Most of the relevant automatic control concepts, such as systems interconnection, frequency response, stability analysis, time response, and/or root locus, have been displayed graphically. This type of representation has been considered for years as an excellent way to introduce automatic control concepts.
© 2016 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
20161205T09:30:10Z
Guzmán Sánchez, José Luis
Costa Castelló, Ramon
Dormido Bencomo, Sebastián
Berenguel, Miguel
Modern engineering projects are multidisciplinary and involve the integration of diverse elements. Within this context, automatic control plays a crucial role. Automatic control is an area of knowledge with significant mathematical content, including differential equations, linear algebra, differential geometry, and/or complex variable among others. Consequently, in many cases, automatic control is difficult for most students to grasp, especially in those cases where students have only an introductory control course in their engineering curriculum. Thus, teachers look for ways to introduce and make automatic control attractive for the students. From the very beginning, graphical representation has been used as support in automatic control teaching. Looking back to the pioneering books in automatic control, it can be seen that there are plenty of schematics and figures. Graphical abstraction was also used to contribute to theoretical understanding. Most of the relevant automatic control concepts, such as systems interconnection, frequency response, stability analysis, time response, and/or root locus, have been displayed graphically. This type of representation has been considered for years as an excellent way to introduce automatic control concepts.

Economic MPC for the Energy Management of Hybrid Vehicles including Fuel Cells and Supercapacitors.
http://hdl.handle.net/2117/97747
Economic MPC for the Energy Management of Hybrid Vehicles including Fuel Cells and Supercapacitors.
Puig Cayuela, Vicenç; Costa Castelló, Ramon; Sampietro, Jose Luis
This paper addresses the energy management of hybrid vehicles using an economicallyoriented model predictive control (EMPC) approach. A control modelling methodology is proposed based on considering the power flows that can be applied to the management of any hybrid vehicle configuration. Then, the proposed EMPC approach is formulated and the control objectives are formulated in terms of a multiobjective cost function. The proposed EMPC is illustrated in a hybrid vehicle that has a PEM fuel cell, a supercapacitor, a battery and a regenerative brake.
20161205T09:21:03Z
Puig Cayuela, Vicenç
Costa Castelló, Ramon
Sampietro, Jose Luis
This paper addresses the energy management of hybrid vehicles using an economicallyoriented model predictive control (EMPC) approach. A control modelling methodology is proposed based on considering the power flows that can be applied to the management of any hybrid vehicle configuration. Then, the proposed EMPC approach is formulated and the control objectives are formulated in terms of a multiobjective cost function. The proposed EMPC is illustrated in a hybrid vehicle that has a PEM fuel cell, a supercapacitor, a battery and a regenerative brake.

Influence of the controller design on the accuracy of a forward dynamic simulation of human gait
http://hdl.handle.net/2117/97085
Influence of the controller design on the accuracy of a forward dynamic simulation of human gait
Pàmies Vila, Rosa; Pätkau, Olga; Dòria Cerezo, Arnau; Font Llagunes, Josep Maria
The analysis of a captured motion can be addressed by means of forward or inverse dynamics approaches. For this purpose, a 12 segment 2D model with 14 degrees of freedom is developed and both methods are implemented using multibody dynamics techniques. The inverse dynamic analysis uses the experimentally captured motion to calculate the joint torques produced by the musculoskeletal system during the movement. This information is then used as input data for a forward dynamic analysis without any control design. This approach is able to reach the desired pattern within half cycle. In order to achieve the simulation of the complete gait cycle two different control strategies are implemented to stabilize all degrees of freedom: a proportional derivative (PD) control and a computed torque control (CTC). The selection of the control parameters is presented in this work: a kinematic perturbation is used for tuning PD gains, and pole placement techniques are used in order to determine the CTC parameters. A performance evaluation of the two controllers is done in order to quantify the accuracy of the simulated motion and the control torques needed when using one or the other control approach to track a known human walking pattern.
20161123T10:08:37Z
Pàmies Vila, Rosa
Pätkau, Olga
Dòria Cerezo, Arnau
Font Llagunes, Josep Maria
The analysis of a captured motion can be addressed by means of forward or inverse dynamics approaches. For this purpose, a 12 segment 2D model with 14 degrees of freedom is developed and both methods are implemented using multibody dynamics techniques. The inverse dynamic analysis uses the experimentally captured motion to calculate the joint torques produced by the musculoskeletal system during the movement. This information is then used as input data for a forward dynamic analysis without any control design. This approach is able to reach the desired pattern within half cycle. In order to achieve the simulation of the complete gait cycle two different control strategies are implemented to stabilize all degrees of freedom: a proportional derivative (PD) control and a computed torque control (CTC). The selection of the control parameters is presented in this work: a kinematic perturbation is used for tuning PD gains, and pole placement techniques are used in order to determine the CTC parameters. A performance evaluation of the two controllers is done in order to quantify the accuracy of the simulated motion and the control torques needed when using one or the other control approach to track a known human walking pattern.

Hands on laboratory for classical nonlinear control systems : the deadzone case.
http://hdl.handle.net/2117/91056
Hands on laboratory for classical nonlinear control systems : the deadzone case.
Lampon Diestre, Cristina; Costa Castelló, Ramon; Dormido Bencomo, Sebastián
Although many control systems are influenced by static nonlinearities, most current handson laboratories will not show this type of behavior. An analog board module, along with the classic setup plants, would provide a series of nonlinearities, whose effect could be studied and comprehended by students. This paper describes the mentioned analog board module, focusing on the deadzone nonlinearity.
20161025T10:20:13Z
Lampon Diestre, Cristina
Costa Castelló, Ramon
Dormido Bencomo, Sebastián
Although many control systems are influenced by static nonlinearities, most current handson laboratories will not show this type of behavior. An analog board module, along with the classic setup plants, would provide a series of nonlinearities, whose effect could be studied and comprehended by students. This paper describes the mentioned analog board module, focusing on the deadzone nonlinearity.