Articles
IET Power Electronics (17554543)18(1)
This paper presents a novel high-performance and dependable step-up multi-level inverter topology designed specifically for photovoltaic applications. A gain factor of nine is attained, coupled with automatic self-voltage balancing of capacitors and the intrinsic capability to generate both positive and negative voltage levels. All power switches withstand voltages lower than the peak of the output voltage. The quantity of power switches, DC input sources, and the blocking voltage on the switches are reduced. Also, the proposed inverter demonstrates a minimal cost function in comparison to similar topologies. The performance of the 19-level step-up inverter has been confirmed through simulation as well as laboratory results obtained from a constructed prototype. © 2025 The Author(s). IET Power Electronics published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.
Chemical Engineering Communications (00986445)212(8)pp. 1233-1242
In this article, a robust control algorithm is proposed for a nonlinear and time-varying continuous stirred tank reactor (CSTR) with sediment formation in the cooling jacket. The existing control schemes may fail, as deposition measurement or estimation is a challenge in such a process. As a main contribution, the deposition phenomenon is modeled here as the system uncertainty. Then, an identification-based robust integral controller is constructed for the underlying CSTR. Applying the loop-shaping procedure here is also a novelty to satisfy the performance objectives in the frequency domain. In a comprehensive scenario, which includes the set-point tracking in the presence of system uncertainties and external disturbance, the performance of the proposed robust control system is evaluated and discussed from a comparison viewpoint. The numerical study shows that fouling control and robust performance are ensured by the developed H∞-based technique. © 2025 Taylor & Francis Group, LLC.
International Journal of Systems Science (00207721)56(8)pp. 1726-1741
Piezoelectric deformable mirrors are complex systems with a reflective face-sheet and underlying actuators. The inherent hysteresis phenomenon in piezoelectric materials introduces nonlinearity and delay, rendering conventional control methods inappropriate for deformable mirror actuation. This study presents a disturbance observer-based controller with the generalised Bouc–Wen hysteresis parameter identification algorithm. Analytical proofs establish fixed-time stability for the observer and controller. A key feature of the proposed disturbance observer is the convergence of the estimated hysteresis to the actual value after a prescribed settling time, which facilitates precise hysteresis parameter identification. This is based on a data clustering technique, unlike most previous works. The proposed controller has the capability of hysteresis compensation and reference tracking in the piezoelectric deformable mirror actuators. Numerical simulation results are present to evaluate the tracking performance of the controller in the presence of random wavefront, the convergence of disturbance to the actual value in the fixed time, and identification of hysteresis parameters. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
International Journal of Systems Science (00207721)56(8)pp. 1784-1800
This paper investigates incrementally input-to-state stability ((Formula presented.) ISS) for the interconnection of infinitely many finite-dimensional discrete-time switched subsystems (DtSS), using finite-step Lyapunov functions (FSLF). Unlike many previous investigations, each subsystem in the network may be not necessarily δISS, considering the potential effects of subsystems on each other. The proposed analysis method shows that the size of the truncation of an infinite network does not need to be known. As an application, assuming the subsystems only need to have M-step approximate bisimilarity relations, it is possible to construct approximately bisimilar abstractions, under small-gain type conditions. The effectiveness of the proposed technique is illustrated through an islanded microgrid, consisting of infinitely many subsystems. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
ISA Transactions (00190578)164pp. 1-13
Data-driven control methods in the frequency domain commonly require the determination of controller structure. Relaxing such restriction in the proposed algorithm, the controller design is transformed into an optimization problem, based on the υ-gap Metric criterion. By defining a desired stability margin and the desired frequency response of the controller, a criterion is determined to characterize a family of controllers. Therefore, a model free procedure is proposed to determine a family of controllers, by taking the plant frequency response and the desired stability margin. On the other hand, by adopting a new index, presented in this paper, the designer can determine the optimal controller, based on the implementation conditions. Another advantage of the proposed method is its applicability to uncertain Multi-Input Multi-Output (MIMO) systems. The loop performance in the presented algorithm can be also enhanced by appropriate selection of weighting matrices in a loop shaping procedure. Two examples are also presented to demonstrate the effectiveness of the method for multi-variable non-square uncertain systems, including a practical example of a purely delayed system. © 2025 ISA