Passive Output Feedback Research Articles

Angular speed control of an induction motor via a solar powered boost converter-voltage source inverter combination

This paper proposes a maximum power point tracking (MPPT) algorithm for the development of a three-phase induction motor angular speed drive. A Dc-to-Dc boost power converter, powered by photovoltaic (PV) panels, feeds the three-phase power inverter. The MPPT algorithm is based on the Exact Static Error Dynamics Passive Output Feedback Controller (ESEDPOF) technique together with an Algebraic Estimator of the impedance. The estimated value is the equivalent impedance that exists between the boost converter and the three-phase inverter, and then this value is used in real-time to generate the desired reference variables of the MPPT algorithm. The angular speed-tracking controller for the induction motor is based on the well-known Field-Oriented Control (FOC) technique. An Experimental set-up was developed using an array of two PV panels. Then, a realistic scenario is carried out, and real-time results at low-speed, with and without load, are presented in order to show the effectiveness and robustness of the proposed MPPT scheme. Under this scenario, the boost converter achieves an electric power efficiency of 80%, when a nominal load torque is applied to the induction motor shaft.

A Trajectory Tracking Control for a Boost Converter‑Inverter‑DC Motor Combination

In this work the trajectory tracking control is solved for the “DC/DC Boost converter‑inverter‑DC motor”. In the control design, the exact tracking error dynamics passive output feedback (ETEDPOF) methodology is used. So, a control that does not require electromechanical sensors for its implementation is yield. The generation of the reference trajectories, required by the control based on the ETEDPOF, is achieved via differential flatness. Finally, the experimental validation of the control is performed in a built system, along with the use of Matlab-Simulink and a DS1104 board. The obtained experimental results show the good performance of the designed control.

Nonlinear Observer-Based Robust Passive Control of Doubly-Fed Induction Generators for Power System Stability Enhancement via Energy Reshaping

The large-scale penetration of wind power might lead to degradation of the power system stability due to its inherent feature of randomness. Hence, proper control designs which can effectively handle various uncertainties become very crucial. This paper designs a novel robust passive control (RPC) scheme of a doubly-fed induction generator (DFIG) for power system stability enhancement. The combinatorial effect of generator nonlinearities and parameter uncertainties, unmodelled dynamics, wind speed randomness, is aggregated into a perturbation, which is rapidly estimated by a nonlinear extended state observer (ESO) in real-time. Then, the perturbation estimate is fully compensated by a robust passive controller to realize a globally consistent control performance, in which the energy of the closed-loop system is carefully reshaped through output feedback passification, such that a considerable system damping can be injected to improve the transient responses of DFIG in various operation conditions of power systems. Six case studies are carried out while simulation results verify that RPC can rapidly stabilize the disturbed DFIG system much faster with less overshoot, as well as supress power oscillations more effectively compared to that of linear proportional-integral-derivative (PID) control and nonlinear feedback linearization control (FLC).

Output feedback passification of saturated switched systems

ABSTRACTThis paper addresses the passivity and feedback passification of the saturated switched systems. A switching law and output feedback controllers are designed such that the corresponding closed-loop systems are with the passivity and disturbance tolerance capacity. The switching law satisfies a maximal dwell time (DT) condition, which avoids too high switching frequency. More importantly, under the switching law, the storage function is allowed to be increased during the DT and then decreased due to the drop of itself at the mixed time/state-dependent switching instants. This releases the performance requirement of existing results where the storage function must be non-increasing all the time. Finally, the existence of the upper bound of DT and output feedback controllers is guaranteed by solving some linear matrix inequalities. Two examples are given to show the effectiveness of the proposed method.

A Sensorless Passivity-Based Control for the DC/DC Buck Converter‑Inverter‑DC Motor System

In order to solve the trajectory tracking task associated with the bidirectional DC/DC Buck power converter‑inverter‑DC motor system, a sensorless passivity-based control is presented for the first time. In particular, the exact tracking error dynamics passive output feedback (ETEDPOF) methodology is used. To this end, the required nominal trajectories for the synthesis of the ETEDPOF-based control are defined by means of the system differential flatness property. With the intention of verifying the designed control performance, experimental tests are accomplished through Matlab-Simulink, ControlDesk, and a DS1104 board. The obtained experimental results show a good performance of the ETEDPOF-based control.

Output Feedback Passification of Saturated Switched Systems Under the Improved State-Dependent Switching

This paper focuses on the passivity analysis and feedback passification of discrete-time switched systems with actuator saturation. The proposed framework consists of a switching law and a bank of time-varying output feedback controllers. The switching law is depending on partial state measurements and switching-delay slack matrix, which avoid the possible too frequent switching caused by the classical state-dependent switching law. The resulting time-varying saturated controllers associated with the switching law are constructed to guarantee the passivity of the closed-loop systems. In addition, the performance index measuring the level of unknown input tolerance capacity of the systems can be also estimated. Sufficient conditions for the existence of the switching law and controllers are provided via Lyapunov---Metzler inequalities. Finally, the effectiveness of the theoretical results is illustrated through an example derived from the stirred tank reactor.

Synchronization of Goodwin's Oscillators under Boundedness and Nonnegativeness Constraints for Solutions

In the recent paper by Hamadeh et al. (2012) an elegant analytic criterion for incremental output feedback passivity (iOFP) of cyclic feedback systems (CFS) has been reported, assuming that the constituent subsystems are incrementally output strictly passive (iOSP). This criterion was used to prove that a network of identical CFS can be synchronized under sufficiently strong linear diffusive coupling. A very important class of CFS consists of biological oscillators, named after Brian Goodwin and describing self-regulated chains of enzymatic reactions, where the product of each reaction catalyzes the next reaction, while the last product inhibits the first reaction in the chain. Goodwin's oscillators are used, in particular, to model the dynamics of genetic circadian pacemakers, hormonal cycles and some metabolic pathways. In this paper we point out that for Goodwin's oscillators, where the individual reactions have nonlinear (e.g. Mikhaelis-Menten) kinetics, the synchronization criterion, obtained by Hamadeh et al., cannot be directly applied. This criterion relies on the implicit assumption of the solution boundedness, dictated also by the chemical feasibility (the state variables stand for the concentrations of chemicals). Furthermore, to test the synchronization condition one needs to know an explicit bound for a solution, which generally cannot be guaranteed under linear coupling. At the same time, we show that these restrictions can be avoided for a nonlinear synchronization protocol, where the control inputs are "saturated" by a special nonlinear function (belonging to a wide class), which guarantees nonnegativity of the solutions and allows to get explicit ultimate bounds for them. We prove that oscillators synchronize under such a protocol, provided that the couplings are sufficiently strong.

Quantized Passive Dynamic Output Feedback Control with Actuator Failure

This paper investigates the problem of passive dynamic output feedback control for fuzzy discrete nonlinear systems with quantization and actuator failures, where the measurement output of the system is quantized by a logarithmic quantizer before being transferred to the fuzzy controller. By employing the fuzzy-basis-dependent Lyapunov function, sufficient condition is established to guarantee the closed-loop system to be mean-square stable and the prescribed passive performance. Based on the sufficient condition, the fuzzy dynamic output feedback controller is proposed for maintaining acceptable performance levels in the case of actuator failures and quantization effects. Finally, a numerical example is given to show the usefulness of the proposed method.

Passivity and output feedback passification of switched continuous-time systems with a dwell time constraint

This paper is concerned with the passivity analysis and output feedback passification for a class of switched continuous-time systems. A switching law and control units are designed to guarantee the passivity of closed-loop switched systems. Different from the exist results in state-dependent switching framework, we construct a novel switching law such that the switched system obeys a minimal dwell time between any two consecutive switchings. This avoids the possible arbitrarily fast switching caused by state-dependent switching law. Moreover, the switching law uses only the lower bound of the dwell time and partial measurable states of the closed-loop system, which is applicable in output feedback framework. Using multiple discretized storage functions, the controllers working on different time intervals are obtained, which ensure the closed-loop system is passive under the switching law. Finally, two examples are provided to illustrate the effectiveness of the developed results.

Sensorless load torque estimation and passivity based control of buck converter fed DC motor.

Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.

Output Feedback Passification of Switched Continuous-Time Linear Systems Subject to Saturating Actuators

This paper is concerned with the output feedback passification of switched continuous-time linear systems with actuation saturation. A switching law and saturated output feedback controllers with t...

Neural Network-based Adaptive Passive Output Feedback Control for MIMO Uncertain System

A neural network--based adaptive passive output feedback control problem is studied for a class of multi-input multi-output nonlinear systems with unknown nonlinearities and unknown parameters. Neural networks are used to identify unknown nonlinearities, and the update laws of weight parameters and constant parameters are proposed. The design methods of the adaptive passive controllers for this class of systems are discussed in the paper. The corresponding adaptive passive controllers and parametric adaptive laws are designed and presented respectively. It is proved that the closed-loop system composed of the original system and the designed controller is stable by the Lyapunov method, and the controller designed can render the closed system adaptive passive. Finally, a simulation example is given to prove the effectiveness and feasibility of the proposed method. DOI: http://dx.doi.org/10.11591/telkomnika.v10i6.1600 Full Text: PDF

Passivity-Based Controller and Online Algebraic Estimation of the Load Parameter of the DC-to-DC power converter Cuk Type

This paper presents an exact static error dynamics passive output feedback controller to regulate the output voltage of the DC-to-DC power converter Cuk type; this controller is obtained from the error dynamics of the nonlinear average model of the converter. In order to compensate the effects of sudden changes in the load resistance, the desired reference variables for the regulation task are calculated using the estimated load value obtained via an algebraic estimator. The results are validated in an experimental laboratory setup.

Load Torque Estimation and Passivity-Based Control of a Boost-Converter/DC-Motor Combination

An algebraic approach is presented for the fast feed-forward adaptation of the angular velocity trajectory tracking task in a Boost-converter driven dc-motor system. For the adaptation, the load torque perturbations are assumed piecewise constant and are, nonasymptotically, online estimated using the available noisy measurements of the state variables. The controller is a linear controller based on the exact tracking error dynamics passive output feedback (ETEDPOF) controller design methodology including suitable adaptive feed-forward precompensation depending explicitly on the precisely estimated torque. The performance of the adaptation, which is achieved by means of the algebraic online-estimation of the current unknown load torque, is successfully validated in an experimental laboratory setup.

Passive output feedback control for non-linear systems with time delays

This paper focuses on the passive output feedback control problem for a class of non-linear systems with time delays. By using multilayer neural networks as an off-line-aided design tool, a dynamic output feedback controller with certain dissipation is developed using the passive control theory in terms of linear matrix inequalities (LMIs), which guarantees the closed-loop system asymptotically stable and strictly passive. It is shown that the solvability of the passive controller design problem is implied by the feasibility of LMIs. A numerical example is given to demonstrate the validity of the proposed approach.

On Some Nonlinear Current Controllers for Three-Phase Boost Rectifiers

Several flatness-based current controllers for three-phase three-wire boost rectifiers are compared. For this purpose, the flatness of a rectifier model is shown, and a trajectory planning algorithm that nominally achieves voltage regulation in finite time is given. The main focus lies on the inner loop current controllers. On one hand, linearization-based controllers using exact feedback linearization, exact feedforward linearization, and input-output linearization are discussed. On the other hand, two passivity-based approaches are compared. The first one is the energy shaping and damping injection method, and the other one uses exact tracking error dynamics passive output feedback. Furthermore, a reduced-order load observer is given, and a method that allows the prevention of invalid switching patterns is presented. The presented control algorithms are tested by simulations on a switched model.

Robust Output Feedback Passification of Linear Systems with Unmodeled Dynamics

For the first time it is proposed and proved that some multi-input multi-output linear systems with unmodeled dynamics can be robustly rendered strictly positive real via static output feedback. In this work, various kinds of unstructured uncertainties are considered, sufficient conditions ensuring robust feedback passification are exploited, and feasible feedback gains are calculated. This new result generalizes existing ones which only deal with exactly modeled systems. It may also play an important role in output feedback variable structure control synthesis.

Dynamic Operability Analysis for Stable and Unstable Linear Processes

Dynamic operability analysis determines the achievable control performance for a given process. Based on open-loop models, such analysis is useful in revealing controllability problems in the early process design stages. This paper presents a new approach to dynamic operability analysis based on the concept of passive systems. It is well-known that passive systems are very easy to control. The lack of passivity of a nonpassive process can be quantified by using an input feedforward passivity (IFP) or an output feedback passivity (OFP) index, which measures how much feedforward/feedback is required to render the process passive. A nonminimum phase stable process usually has a shortage of IFP and thus needs a controller with an excessive OFP to ensure closed-loop stability. Excessive OFP of the controller represents the upper limit of the controller gain. Therefore, the shortage of IFP of a stable process can be used to determine its achievable performance. This analysis is then extended to unstable processes using coprime factorization. Numerical methods for dynamic operability analysis for both stable and unstable processes are developed in this paper.

AN ALGEBRAIC PARAMETER ESTIMATION APPROACH FOR THE ADAPTIVE OBSERVER-CONTROLLER BASED REGULATION OF THE “BOOST” CONVERTER

In this article, a new approach is proposed for the problem of output voltage reference trajectory tracking in a “boost” converter with unknown, piecewise constant, load resistance values, under the restriction of noisy output voltage measurements alone. We use a nonlinear algebraic parameter estimation approach for the fast computation of the actual value of the stepwise changing load. With this information, a reduced order nonlinear observer for the inductor current is updated as well as a static passive output feedback control law derived on the basis of the exact tracking error dynamics and Lyapunov stability considerations. The average nonlinear adaptive observer-controller scheme is implemented on the switch regulated converter using the averaging features of a SM – Δ modulator.

Passivity-based Feedback Design for Polynomial Control Systems (Passivitätsbasierter Reglerentwurf für polynomiale Systeme)

Abstract This paper proposes a simple computer-aided feedback design strategy for polynomial control systems. The design strategy is based on passivity and semidefinite programming, two well-established concepts from control theory and optimization. The combination of these two concepts leads to a physically motivated feedback design strategy which can be efficiently and reliably solved on a computer. In particular, this paper addresses the problem of designing globally stabilizing feedbacks via state feedback passivation and via dynamic output feedback passivation using semidefinite programming and the sum of squares decomposition.