TY - GEN A1 - Estrada, Manuel A. A1 - Rueda-Escobedo, Juan G. A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - Systematic and robust tuning of proportional-resonant controllers for current and voltage tracking T2 - 2025 IEEE Conference on Control Technology and Applications (CCTA), August 25-27, 2025, San Diego, CA, USA N2 - In the control and operation of power inverters, proportional-resonant (PR) controllers are used to track references and reject disturbances that can be described by a sum of sinusoidal signals of known frequency. The relevance of these controllers is increasing due to the increase in distortion and volatility of three-phase signals in the grid. However, as reported in the literature, the tuning of PR controllers is far from trivial due to their large number of parameters and the presence of pure imaginary poles in the associated transfer function. To address these issues, a time-domain framework based on linear matrix inequalities (LMIs) is presented for the tuning of PR controllers with applications to voltage and current tracking. The advantage of this approach is the straightforward combination with other techniques such as H∞ control. The effectiveness of the approach is illustrated through numerical simulations, where the injection of a constant active power is achieved in the presence of distorted voltages. Y1 - 2025 SN - 979-8-3315-3908-5 U6 - https://doi.org/10.1109/CCTA53793.2025.11151423 SN - 0018-9286 SN - 2768-0770 SP - 768 EP - 773 PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Texis-Loaiza, Oscar A1 - Moreno, Jaime A. A1 - Estrada, Manuel A. A1 - Fridman, Leonid A1 - Levant, Arie T1 - Output feedback control of nonlinear systems via Lipschitz continuous sliding modes T2 - IEEE control systems letters N2 - This letter proposes a Lipschitz continuous output feedback sliding mode control law applicable to systems of arbitrary relative degree. The proposed controller compensates for non-vanishing perturbations with bounded time derivatives while ensuring finite-time stability of the origin. The finite-time stability of the closed-loop system is established using Lyapunov methods, leveraging the weighted homogeneity properties of both the controller and the observer. Furthermore, the observer and controller can be designed independently, thereby establishing a form of separation principle. The feasibility of the proposed method is demonstrated through simulation. KW - Nonlinear output feedback KW - Sliding mode control KW - Higher-order sliding-mode control KW - Finite-time convergence KW - Lyapunov methods Y1 - 2025 U6 - https://doi.org/10.1109/LCSYS.2025.3570982 SN - 2475-1456 VL - 9 SP - 378 EP - 383 PB - IEEE CY - New York, NY ER - TY - GEN A1 - Texis-Loaiza, Oscar A1 - Estrada, Manuel A. A1 - Fridman, Leonid A1 - Moreno, Jaime A. A1 - Levant, Arie T1 - Output feedback control of second-order systems via Lipschitz continuous sliding modes T2 - 2024 17th International Workshop on Variable Structure Systems (VSS) N2 - This paper presents an output feedback approach for second-order systems with non-vanishing perturbations. The proposed approach allows us to compensate for non-vanishing Lipschitz perturbations theoretically exactly while generating a Lipschitz continuous control signal, reducing the energy consumption by the control. To achieve such a Lipschitz continuous sliding mode control, we propose a homogeneous third-order sliding mode control law and a second-order sliding mode observer; then, we prove the finite-time stable equilibrium in a closed loop with the system. The feasibility of the result is shown through a simulation example. KW - High-order sliding-mode control KW - Disturbance rejection KW - Robust control KW - Lyapunov methods KW - Finite-time convergence Y1 - 2024 SN - 979-8-3503-5368-6 U6 - https://doi.org/10.1109/VSS61690.2024.10753385 SN - 1524-9050 SP - 220 EP - 225 PB - IEEE CY - New York, NY ER - TY - GEN A1 - Gustavo-Escobedo, Juan A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - Finite-Time Estimation of Time-Varying Frequency Signals in Low-Inertia Power Systems T2 - 8th European Control Conference (ECC) N2 - The ongoing and unprecedented transformation of power systems leads to a reduction in the number of conventional power plants, which are the classical actuators of the grid. In addition, this development results in a decreasing system inertia, which is expected to yield faster frequency dynamics. Therefore power-electronics-interfaced units have to take over system control tasks and, in particular, frequency control. For this purpose, accurate and fast estimation algorithms for time-varying frequency signals are needed. Motivated by this fact, we propose a time-varying parameter estimator and a tuning criterion, which for sufficiently small initial estimation errors allows to reconstruct the time-varying frequency signal of a symmetric three-phase waveform in finite time. The proposed estimator is derived by using a time-varying version of the super twisting algorithm and its performance is illustrated via numerical examples. KW - Power Systems, Frequency Signals, Finite-Time Estimation Y1 - 2019 U6 - https://doi.org/10.23919/ECC.2019.8795926 SP - 2108 EP - 2114 ER - TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Ushirobira, Rosane A1 - Efimov, Denis A1 - Moreno, Jaime A. T1 - Gramian-based uniform convergent observer for stable LTV systems with delayed measurements T2 - International Journal of Control Volume N2 - In this work, an observer for a linear time-varying system with delayed measurements is developed. The delay is assumed to be unknown, bounded, and it can be time-varying with no restriction on its rate of change. The observer uses auxiliary signals related to the constructibility Gramian of the system and it contains nonlinearities that provide a uniform fixed-time convergence to a bounded region in the estimation error coordinates. This means that the convergence time can be bounded by a positive constant which is independent from the initial conditions and the initial time. This property is new for the addressed class of systems. The ultimate bound of the estimation error depends on the maximum difference between the nominal output and the delayed one, and not directly on the delay size or its time derivative. These properties are illustrated in a numerical simulation. Y1 - 2020 U6 - https://doi.org/10.1080/00207179.2019.1569256 SN - 0020-7179 SN - 1366-5820 VL - 93 IS - 2 SP - 226 EP - 237 ER - TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Moreno, Jaime A. T1 - Strong Lyapunov Functions for Two Classical Problems in Adaptive Control T2 - Automatica N2 - Strong Lyapunov functions for two classical problems in adaptive control and parameter identification are presented. These Lyapunov functions incorporate in their structure the classical persistency of excitation conditions, allowing to show global uniform asymptotic stability of the associated adaptive systems under sufficient and necessary conditions. Y1 - 2021 U6 - https://doi.org/10.1016/j.automatica.2020.109250 VL - 124 ER - TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Sbarciog, Mihaela A1 - Moreno, Jaime A. A1 - Van Impe, Jan A1 - Wouwer, Alain Vande T1 - Robust State and Input Estimation with Enhanced Convergence Rate for Monitoring Anaerobic Digestion T2 - Journal of Process Control N2 - In this study, an observer for estimating the state and unknown inputs is proposed for monitoring anaerobic digestion processes. This estimator is based on a dynamic model considering acidogenesis and methanogenesis, and consists of three sub-observers: (a) a gramian-based fixed-time convergent observer for the inlet chemical oxygen demand (COD) and the acidogenic bacteria population, (b) an asymptotic observer for the methanogenic bacteria population, and (c) a super-twisting observer for systems with time-varying parameters to estimate the inlet volatile fatty acid (VFA) concentration. These sub-observers can be designed independently, which greatly simplifies the tuning process. Proofs of convergence are developed and simulation tests show the performance of the estimation scheme as compared to classical extended Kalman filtering. Y1 - 2022 UR - https://www.sciencedirect.com/science/article/pii/S0959152422001421 U6 - https://doi.org/10.1016/j.jprocont.2022.07.014 SN - 0959-1524 VL - 117 IS - 4 SP - 169 EP - 180 ER - TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - L2-Gain Tuning for the Gradient Descent Algorithm in the Presence of Disturbances T2 - 2022 European Control Conference (ECC) N2 - Due to its simplicity and inexpensive computation, the gradient descent algorithm is one of the most used tools in adaptive control and system identification. Although it has been studied for decades, little has been achieved in terms of tuning methods in the presence of disturbances. One of the main difficulties in its analysis is the time-varying nature of the algorithm. In this work, we contribute in such direction by providing LMI tools for tuning the gradient descent algorithm gain such that a guaranteed upper bound on the L2 -gain with respect to parameter variations and measurement noise is achieved. Two academic examples are provided to illustrate the efficient application of the method. KW - Upper bound KW - Gain measurement KW - Minimization KW - robustness KW - system identification KW - noise measurement Y1 - 2022 UR - https://ieeexplore.ieee.org/document/9838051 SN - 978-3-9071-4407-7 U6 - https://doi.org/10.23919/ECC55457.2022.9838051 SP - 1610 EP - 1616 PB - IEEE CY - Piscataway ER - TY - GEN A1 - Rueda-Escobedo, Juan G. A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - Design and Tuning of the Super-Twisting-Based Synchronous Reference Frame Phase-Locked-Loop T2 - 2022 IEEE 61st Conference on Decision and Control (CDC) ; December 6-9, 2022, Cancun, Mexico N2 - The worldwide transition to climate-friendly energy systems entails the substitution of conventional energy generation based on synchronous generators by renewable energy sources based on power electronics. As a consequence, the overall inertia of the grid decreases, resulting in high volatility of the frequency and posing new challenges for the estimation of the latter quantity. To address this problematic, in the present paper a phase-locked-loop (PLL) based on the super-twisting algorithm is considered for the estimation of the phase angle and time-varying frequency of a symmetric three-phase signal. A rigorous proof of the algorithm’s exact convergence in the presence of a fast-varying frequency together with tuning rules for its gains are derived by means of Lyapunov theory. Additionally, an estimate of the region of attraction is provided. The effectiveness of the proposed tuning method is illustrated in numerical simulations, while comparing its performance against a standard synchronous reference frame PLL. Y1 - 2022 UR - https://css.paperplaza.net/conferences/conferences/CDC22/program/CDC22_ContentListWeb_3.html ER - TY - GEN A1 - Lorenz-Meyer, Nicolai A1 - Rueda-Escobedo, Juan G. A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - A robust consensus + innovations-based distributed parameter estimator T2 - IEEE transactions on automatic control N2 - While distributed parameter estimation has been extensively studied in the literature, little has been achieved in terms of robust analysis and tuning methods in the presence of disturbances. However, disturbances such as measurement noise and model mismatches occur in any real-world setting. Therefore, providing tuning methods with specific robustness guarantees would greatly benefit the practical application. To address these issues, we recast the error dynamics of a continuous-time version of the widely used consensus + innovations-based distributed parameter estimator to reflect the error dynamics induced by the classical gradient descent algorithm. This paves the way for the construction of a strong Lyapunov function. Based on this result, we derive linear matrix inequality-based tools for tuning the algorithm gains such that a guaranteed upper bound on the L2-gain with respect to parameter variations, measurement noise, and disturbances in the communication channels is achieved. An application example illustrates the efficiency of the method. KW - Distributed parameter estimation KW - Sensor networks KW - System identification KW - Time-varying systems Y1 - 2025 U6 - https://doi.org/10.1109/TAC.2025.3597563 SN - 0018-9286 SN - 1558-2523 SP - 1 EP - 15 PB - IEEE CY - New York, NY ER - TY - GEN A1 - Texis-Loaiza, Oscar A1 - Mercado-Uribe, Angel A1 - Moreno, Jaime A. A1 - Schiffer, Johannes T1 - A finite-time convergent primal-dual gradient dynamics based on the multivariable super-twisting algorithm T2 - 2025 European Control Conference (ECC) N2 - We propose a novel primal-dual gradient dynamics (PDGD) algorithm to dynamically solve an optimization problem with linear equality constraints in finite time. To ensure finite-time convergence, we endow the PDGD with suitable homogeneity properties. More precisely, departing from the standard PDGD and based on the associated Lagrangian of the optimization problem, the algorithm is derived by suitably combining a change of coordinates of the standard PDGD with the multivariable super-twisting algorithm. In our new coordinates, the proposed PDGD’s global convergence to the optimal solution of the optimization problem is then proven via a smooth, strong Lyapunov function. Additionally, we provide a numerical example to compare the performance of our algorithm with existing approaches from the literature. Y1 - 2025 SN - 978-3-907144-12-1 U6 - https://doi.org/10.23919/ECC65951.2025.11186834 SP - 1892 EP - 1898 PB - IEEE CY - New York, NY ER - TY - GEN A1 - Texis-Loaiza, Oscar A1 - Moreno, Jaime A. A1 - Mercado-Uribe, Angel A1 - Schiffer, Johannes T1 - A third-order bl-homogeneous sliding mode observer for uncertain triangular nonlinear systems T2 - 2025 European Control Conference (ECC) N2 - In this paper, we propose a global third-order homogeneous in the bi-limit sliding mode observer (BL-H SMO) that can estimate the states of an uncertain nonlinear system with unknown inputs in finite time. The system must be strongly observable w.r.t. unknown inputs (UIs) and uniformly observable w.r.t. known inputs. To handle the UIs and non-Lipschitz nonlinearities, the proposed observer combines sliding-mode and high-gain observers, extending the generalized super-twisting observer. The convergence of the BL-H SMO to the system states is proven through a Lyapunov function. Finally, to showcase the effectiveness of the proposed method, the paper includes an academic example and a practical example, namely a three-phase converter with LCL-filter. Y1 - 2025 SN - 978-3-907144-12-1 U6 - https://doi.org/10.23919/ECC65951.2025.11186860 SP - 1955 EP - 1960 PB - IEEE CY - New York, NY ER -