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This brief proposes a new multiple input multiple output (MIMO) control for off-board electric vehicle (EV) dc fast chargers. The proposed feedback matrix design avoids multiple tuning of controllers in multiple and interconnected loops while improving the performance of interleaved dc buck converters over classical PI/PID controls. The innovative features of the presented strategy are the reference current monotonic tracking from any initial state of charge with an arbitrarily fast settling time and the fast compensation of both load variations and imbalances among the legs. Numerical results validate the performance improvements of the proposed discrete-time MIMO algorithm for interleaved buck converters over classical PI/PID controls. Full-scale hardware-in-the-loop (HIL) and scaled-down prototype experimental results prove the feasibility and effectiveness of the proposal.

In this article, we study the problem of estimation in the presence of disturbances within the context of the behavioral approach developed by J.C. Willems. For this purpose, we use the behavioral theory of observers introduced by Valcher, Willems, Trentelman, and Trumpf, combined with the notions of behavioral invariance, conditioned invariance, and behavioral detectability subspaces. With these tools, we provide necessary and sufficient conditions for the solvability of the aforementioned problem together with the construction of an estimator. [ABSTRACT FROM AUTHOR]

In this paper, we propose an optimization-based tuning methodology for real and complex Fractional-Order Proportional-Integral (FOPI) controllers. The proposed approach hinges on a modified version of the Integral Absolute Error (IAE) sensitivity-constrained optimization problem, which is suitably adapted to the design of fractional controllers. As such, it allows the exploitation of the potentiality of the (possibly complex) fractional integrator. We also propose a method, based on the well-known CRONE approximation, which delivers a band-limited real-rational approximation of the real part of the complex-order integrator. Finally, based on a First-Order-Plus-Dead-Time (FOPDT) model of the process, we use our design and approximation techniques to find an optimal tuning for real, complex fractional-order, and integer PI controllers and we provide a quantitative performance assessment.

In this technical note we lay the foundations of a not necessarily rational negative imaginary systems theory and its relations with positive real systems theory. In analogy with the theory of positive real functions, in our general framework negative imaginary systems are defined in terms of a domain of analyticity of the transfer function and of a sign condition that must be satisfied in such domain. In this way, we do not require to restrict the attention to systems with a rational transfer function. In this work, we also define various grades of negative imaginary systems and aim to provide a unitary view of the different notions that have appeared so far in the literature within the framework of positive real and in the more recent theory of negative imaginary systems, and to show how these notions are characterized and linked to each other. [ABSTRACT FROM AUTHOR]

In this technical note we present a method for designing a linear time invariant (LTI) state-feedback controller to monotonically track a step reference at any desired rate of convergence for any initial condition. This method is developed for multi-input multi-output (MIMO) systems, and can be applied to strictly/nonstrictly proper systems, and also minimum/nonminimum-phase systems. This framework shows that for MIMO systems the objectives of achieving a rapid settling time, while at the same time avoiding overshoot/undershoot, are not always competing objectives. [ABSTRACT FROM AUTHOR]

This paper is concerned with the computation of basis matrices for the subspaces that lie at the core of the so-called geometric approach to control theory, namely the supremal output-nulling, reachability and stabilisability subspaces. Importantly, we also consider the problem of computing the feedback matrices that render these subspaces invariant with respect to the closed loop, while simultaneously assigning the assignable eigenstructure of the closed loop. Differently from the classical techniques presented in the literature so far on this topic, which are based on the standard pole assignment algorithms and are therefore applicable only in the non-defective case, the method presented in this paper can be applied in the case of closed-loop eigenvalues with arbitrary multiplicity.

This technical note introduces a new approach to the solution of a very general class of finite-horizon optimal control problems for discrete-time systems. This approach provides a parametric expression for the optimal control sequences, as well as the corresponding optimal state trajectories, by exploiting a new decomposition of the so-called extended symplectic pencil. This decomposition provides an original strategy for a more direct solution of the problem with no need of the system-theoretic hypotheses (including regularity of the symplectic pencil) that have always been assumed in the literature so far. [ABSTRACT FROM AUTHOR]

We consider the use of linear multivariable state feedback control to achieve a nonundershooting step response. The recently introduced nonovershooting linear state feedback controller design method of Schmid and Ntogramatzidis (2010) is here modified to yield a step response that is nonundershooting. The design method is applicable to square and non-square systems, minimum and nonminimum phase systems, and also strictly proper and bi-proper systems.

In this paper, the concept of self-bounded controlled invariance is extended to nonstrictly proper systems. Moreover, its use in connection with the disturbance decoupling problem with internal stability is investigated in the case where the feedthrough matrices from the control input and from the disturbance to the output to be decoupled are possibly nonzero. [ABSTRACT FROM AUTHOR]

The problem of partial realization is to construct a latent variable model which matches a specified input-output behavior over a bounded frame of interest. In this paper, an algorithm is proposed for constructing a partial realization from the Toeplitz kernel of a possibly noncausal 2-D linear system. By construction, the resulting latent variable model and corresponding boundary conditions comprise four components, each with recursively computable structure. [ABSTRACT FROM AUTHOR]

Several feedforward decoupling and estimation problems are treated here in a unified setting, and their exact geometric solution is extended to the general case where the direct feedthrough matrices of all the systems involved are possibly non-zero. To this end, the concepts of selfboundedness and self-hiddenness are generalised and investigated within the general context of non-strictly proper systems. Then, for each problem considered, solvability conditions are provided as well as the explicit structure of the solving compensator or observer.

Under the mild assumption of sign-controllability, a closed-form expression parameterizing all the solutions of the Hamiltonian differential equation over a finite time interval is presented in terms of a strongly unmixed solution of an algebraic Riccati equation (ARE) and of the solution of an algebraic Lyapunov equation. This result is employed for the solution of a generalized version of the finite-horizon linear quadratic (LQ) problem, encompassing the case of fixed end-point. Furthermore, it is shown how this method can be applied to the H2preview decoupling problem.

Geometric control theory, developed by Basile and Marro, and independently, by Wonham and Morse in the 1970s revolves around characterizing the properties of finite dimensional, linear and time-invariant systems using geometry. Some examples of these properties are invariance, controllability and observability. The task addressed in this paper is to develop the geometric tools for fractional systems using the diffusive representation (also known as the distributed frequency) model. The mathematics involved in this approach is different from the classical case as fractional systems are inherently infinite dimensional. Unlike the integer order derivative, the fractional derivative is a non-local operator, and so the evolution of the so-called pseudo-state depends on not just its current value but also its past history. Thus, the notion of an initial condition for a fractional system can come in different forms. This leads to different kinds of fractional derivative operators. With some of these operators, the semigroup property is lost. With the distributed frequency model, the initial condition comes in the form of an initialization function. This takes care of the infinite dimensional nature of fractional systems. Furthermore, the distributed frequency model retains the semigroup property. This is useful in developing invariance and controlled invariance for fractional systems. Moreover, these properties of fractional systems are verified numerically using a higher order finite-dimensional approximation, which retains all the geometric properties of the distributed frequency model. • Disturbance decoupling for fractional systems. • Geometric control for fractional systems. • Disturbance decoupling via static state feedback. • Disturbance decoupling via dynamic output feedback. • Controlled and conditioned invariance for fractional systems. [ABSTRACT FROM AUTHOR]

In this note it is shown that the main result of refid="ref1"/, concerning a characterization of a pair of structural invariant subspaces associated with the extended symplectic system, is a particular case of a result presented in refid="ref2"/ and refid="ref3"/ within a more general and rigorous context. We also analyse the proof of the main result of refid="ref1"/ , and the way such result is used to accomodate the boundary conditions in the solution of a finite-horizon linear quadratic optimal control problem. [ABSTRACT FROM PUBLISHER]