Papers by Mohammed Benmiloud
IEEE Transactions on Automatic Control, 2018
Most of the proposed controllers for switched affine systems are able to drive the system traject... more Most of the proposed controllers for switched affine systems are able to drive the system trajectory to a sufficiently small neighborhood of a desired state. However, the trajectory behavior in this neighborhood is not generally considered despite the fact that the system performance may be judged by its steady operation as the case of power converters. This note investigates the local stabilization of a desired limit cycle in switched affine systems using hybrid Poincaré map approach. To this end, interesting algebraic properties of the Jacobian of the hybrid Poincaré map are firstly discussed and used for the controller design to achieve asymptotic stability conditions of the limit cycle. A DC-DC four-level power converter is considered as an illustrative example to highlight the developed results.
2017 6th International Conference on Systems and Control (ICSC), 2017
In this paper, a characterization of the optimal limit cycles in the two-phase interleaved boost ... more In this paper, a characterization of the optimal limit cycles in the two-phase interleaved boost converter (2IBC) is presented. The 2IBC inherits the role of the conventional boost converter with other special benefits such as reducing the current and voltage stress, and sharing the input current between two identical phases. Unlike the conventional boost converter, for some given operating point and fixed switching frequency, there exist for the 2IBC an infinity of possible limit cycles of which only one is optimal with respect to the input current ripple. This limit cycle is characterized in all possible conduction modes, as a first step for its stabilization. The optimal limit cycle is characterized by a special execution of the hybrid automaton of the 2IBC.
IFAC-PapersOnLine, 2020
Grid-forming inverters play an important role in supporting power systems with low rotational ine... more Grid-forming inverters play an important role in supporting power systems with low rotational inertia. Their frequency and voltage control policies must guarantee a synchronised operation, accurate power sharing amongst inverters, and a good transient response. Simultaneously achieving the latter two requirements is in general a non-trivial problem and existing schemes in the literature often focus on one of these two aspects. In this paper, we propose a simple frequency controller that uses the inverter output current as feedback to adapt its frequency, and also propose controllers for the regulation of the DC and AC voltages. We show that the proposed control architectures achieve both power sharing without a communication link, and desirable passivity properties that can enhance the dynamic performance. Closed loop stability of the grid-forming inverter with a dynamic load is also proven and simulations on advanced models are carried out to validate the results.
ISA Transactions, 2020
This paper proposes a scheme based on the use of unsupervised machine learning approach and a dri... more This paper proposes a scheme based on the use of unsupervised machine learning approach and a drift detection mechanism in order to perform an early fault diagnosis of simple and multiple stuck-opened/stuck-closed switches in multicellular converters. Only the data samples representing the normal operation conditions are used in order to be adapted to the case where no data is available about faulty behaviors. A health indicator measuring the dissimilarity between normal and current operation conditions is built in order to detect a drift (degradations) in early stage. When a degradation (fault) is detected, the isolation is achieved by taking into account the discrete dynamics of switches. The features related to the latter are extracted in order to build a feature space allowing to separate the faulty behavior (zone or class) of the different switches. The proposed scheme is evaluated using real data samples representing different normal/simple/multiple switch fault scenarios issued from a test rig.
International Journal of Hydrogen Energy, 2017
This paper proposes a novel hybrid fuzzy-PID controller for air supply on Proton Exchange Membran... more This paper proposes a novel hybrid fuzzy-PID controller for air supply on Proton Exchange Membrane fuel cell (PEMFC) systems. The control objective is to adjust the oxygen excess ratio at a given setpoint in order to prevent oxygen starvation and damage of the fuel-cell stack. The proposed control scheme consists of three parts: a fuzzy-logic controller (FLC), a fuzzy-based self-tuned PID (FSTPID) controller and a fuzzy selector. Depending on the value of the error between the current value of oxygen excess ratio and its setpoint value, the fuzzy selector decides which controller should play the greatest effect on the control system. The performance of the proposed control strategy is analysed through simulations for different load variations and for parameter uncertainties. The results show that the novel hybrid fuzzy-PID controller performs significantly better than the classical PID controller and the FLC in terms of several key performance indices such as the Integral Squared Error (ISE), the Integral Absolute Error (IAE) and the Integral Time-weighted Absolute Error (ITAE), as well as the overshoot, settling and rise time for the closed-loop control system.
International Journal of Control, 2017
ABSTRACT This paper addresses the control problem of an important class of hybrid dynamical syste... more ABSTRACT This paper addresses the control problem of an important class of hybrid dynamical systems where the desired state does not belong to the set of subsystem equilibria. Beyond the practical stabilisation where the system trajectory has to be driven to a neighbourhood of a desired state, a control law is designed to solve the limit cycle stabilisation problem for planar hybrid systems. Using the hybrid Poincaré map, two hybrid controllers are developed, which guarantee a local asymptotic/finite-time stability of the desired limit cycle. Illustrative examples are provided to highlight the effectiveness of the derived results.
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016
This paper deals with a hybrid control scheme for two-phase interleaved boost converter devoted t... more This paper deals with a hybrid control scheme for two-phase interleaved boost converter devoted to renewable energy and automotive applications. The control requirements, resumed in low input current ripples, are formulated as an optimal limit cycle stabilization problem, and are solved using hybrid systems formalism. The closed-loop consists in associating each discrete mode to a clearly defined region of the state space, in such a way that the optimal limit cycle is stabilized asymptotically. Mathematical proofs are provided alongside simulations to illustrate the effectiveness and the robustness of the proposed controller, especially with the use of a fuel cell as an input source.
ISA Transactions, 2017
This paper is devoted to the development of a hybrid controller for a two-interleaved boost conve... more This paper is devoted to the development of a hybrid controller for a two-interleaved boost converter dedicated to renewable energy and automotive applications. The control requirements, resumed in fast transient and low input current ripple, are formulated as a problem of fast stabilization of a predefined optimal limit cycle, and solved using hybrid automaton formalism. In addition, a real time estimation of the load is developed using an algebraic approach for online adjustment of the hybrid controller. Mathematical proofs are provided with simulations to illustrate the effectiveness and the robustness of the proposed controller despite different disturbances. Furthermore, a fuel cell system supplying a resistive load through a two-interleaved boost converter is also highlighted.
2015 4th International Conference on Electrical Engineering (ICEE), 2015
This paper presents a fuzzy self-tuning PID controller for air supply on a Proton Exchange Membra... more This paper presents a fuzzy self-tuning PID controller for air supply on a Proton Exchange Membrane (PEM) fuel cell system. The control objective is to adjust the oxygen excess ratio at the suitable value in order to prevent oxygen starvation and damage. The proposed control scheme is separated into two parts: fuzzy tuner and classical PID controller. The parameters of PID controller are adapted by means of fuzzy tuner. Feedforward and classical PID are compared to validate the performance of the fuzzy self-tuning PID control strategy. The simulation results demonstrate that the proposed technique improves the dynamic performance of oxygen excess ratio than classical PID.
Control Engineering Practice, 2016
This paper investigates a new state feedback controller design for DC/DC three-cell converter. Th... more This paper investigates a new state feedback controller design for DC/DC three-cell converter. The high dynamic performances of the converter have been translated into a desired limit cycle stabilization problem. The state feedback is established using hybrid automaton formalism, which allows us to design independently a transitory state and steady state control schemes. Finite-time convergence of the trajectory to the steady state and the local asymptotic stability of the desired limit cycle under the proposed controller are proved analytically. Simulation and experimental results confirm the theoretical results and show the effectiveness and robustness of the hybrid controller in spite of load variations.
2015 3rd International Conference on Control, Engineering & Information Technology (CEIT), 2015
This paper proposes a sliding mode controller for air supply subsystem on a PEM Fuel Cell system ... more This paper proposes a sliding mode controller for air supply subsystem on a PEM Fuel Cell system in order to regulate and replenish the oxygen depleted from the Fuel Cell cathode during stack current demands. According to the stack current, a reference value of air flow was obtained with the steady-state analysis of oxygen excess ratio (OER). To ensure the system working in the reference value of OER, a control scheme includes a sliding mode controller was proposed to adjust the air flow rate provided by the air compressor. Simulation results show that the control methods has good responses against disturbances and uncertainties.
2015 3rd International Conference on Control, Engineering & Information Technology (CEIT), 2015
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Nonlinear Dynamics, 2015
ABSTRACT
This paper proposes a nonlinear dynamic model of proton exchange membrane fuel cell system (PEMFC... more This paper proposes a nonlinear dynamic model of proton exchange membrane fuel cell system (PEMFCs) based on electrochemical, thermodynamic and fluid flow principles. This model represents cathode and anode flow, membrane hydration, stack voltage and the auxiliary components including compressor and manifold filling. Simulations are carried out to analyze the effect of stack current, stack temperature and membrane water content variations on output responses of the PEMFCS.
The field of power electronics poses challenging control problems that can't be treated in a comp... more The field of power electronics poses challenging control problems that can't be treated in a complete manner using traditional modeling. In this paper, the buck converter operating in Continuous Conduction Mode (CCM) is represented analytically by hybrid automaton model and graphically representation is also given. The hybrid trajectory and the model behavior are presented. The control problem of buck switching converters is transformed to a guard selection problem. The guard selection calculation formulas of buck converter are derived from the basic circuit laws. The stability of the switching is established analytically by the use of multiple Lyapunov functions to ensure the convergence and Poincare map to assess the local stability of the limit cycle. Numerical results clearly bring out the advantages and effectiveness of the proposed control law under varying line voltage and load conditions. Simulation studies are carried out in Matlab/Simulink/Stateflow.
3rd International Conference on Systems and Control, 2013
ABSTRACT This paper deals with the analysis and control of multicellular converter from the point... more ABSTRACT This paper deals with the analysis and control of multicellular converter from the point view of hybrid theory. Therefore, a hybrid model, called hybrid automaton, should be established. The hybrid automaton for the multicellular converter is derived based on some properties obtained by the analysis of the open loop trajectories. Based on the obtained hybrid automaton, we derive a switching control law that guaranties the quadratic stability of the switched equilibrium. The continuous Lyapunov function used for the quadratic stabilization is the stored energy in the inductor and the capacitor. The switching surfaces are defined based on the highest rate of decrease of the continuous Lyapunov function. Simulation results bring out the advantages and the effectiveness of the proposed control scheme under fast variations of the input voltage and load resistance.
2013 International Conference on Control, Decision and Information Technologies (CoDIT), 2013
ABSTRACT In the last decades, multicellular converters bring challenging problems toward the maxi... more ABSTRACT In the last decades, multicellular converters bring challenging problems toward the maximum benefit from its large potential. However, this can not be considered efficiently using traditional modeling. This paper proposes new method for hybrid modeling and switching design of multicellular converter taking into account its cyclic behavior. The generalized hybrid automaton is constructed based on some properties obtained by the open loop control analysis. Systematic way for the switching control is proposed to assess the stability and ensure symmetric limit cycle in different phases of variation.
2014 13th International Workshop on Variable Structure Systems (VSS), 2014
ABSTRACT This paper deals with the switching design for two cells converter. With a systematic ma... more ABSTRACT This paper deals with the switching design for two cells converter. With a systematic manner and a geometric analysis, we developed a novel switching surfaces using the sliding mode control theory. The limit cycle of the converter is taken in consideration in the control design phase. The proposed control scheme combines the performances of PWM control techniques (optimal steady state) and the advantages of the direct control strategies (control of the transitory state). This is validated through simulation under fast variations of the input voltage.
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Papers by Mohammed Benmiloud