This work presents a control strategy combining a direct model reference adaptive control (MRAC) with a robust state feedback for current control of grid-connected converters with LCL filters operating under grid impe...
详细信息
This work presents a control strategy combining a direct model reference adaptive control (MRAC) with a robust state feedback for current control of grid-connected converters with LCL filters operating under grid impedance variations. The MRAC is based on a gradient law, providing properly current reference tracking and voltage disturbance rejection. The inclusion of a state feedback inner loop provides robust active damping of the filter resonance for an entire range of grid impedances. A systematic control design procedure is proposed, and the combination of both control actions in a multi-loop approach does not add significant computational complexity. The proposal allows to increase the MRAC gains adaptation dynamics, providing suitable responses under grid current reference variations and under typical grid voltage disturbances, including grid faults. Performance indexes as the grid-currents total harmonic distortion and the mean squared error are also improved. In addition, robust stability analysis based on Lyapunov functions are carried out for the inner control loop and for the outer control loop, considering the grid impedance uncertain and with unmodeled dynamics. The strategy is implemented in a commercial digital signal processor, and the compliance of the grid currents with the IEEE 1547 Std. is verified with controller hardware-in-the-loop and experimental results in a 5.4 kW prototype.
This article develops a disturbance rejection control strategy using partial-state feedback model reference adaptive control for discrete-time uncertain systems with unknown input disturbances. adaptivecontrol scheme...
详细信息
This article develops a disturbance rejection control strategy using partial-state feedback model reference adaptive control for discrete-time uncertain systems with unknown input disturbances. adaptivecontrol schemes are proposed for constant disturbances, sinusoidal disturbances, and generic bounded disturbances. The partial-state feedback control is designed based on measurable signals and the parameterization method to counteract the effect of disturbances. The plant-model output matching condition is established. The developed control law is more flexible for applications and has a more concise structure than output feedback control. Additionally, closed-loop stability and asymptotic output tracking are derived. The effectiveness and the feasibility of partial-state feedback disturbance rejection control are verified by simulation results.
In this paper, a nonlinear modelreferenceadaptive impedance controller is proposed and tested. The controller provides asymptotic tracking of a reference impedance model for the robot end-effector in Cartesian coord...
详细信息
In this paper, a nonlinear modelreferenceadaptive impedance controller is proposed and tested. The controller provides asymptotic tracking of a reference impedance model for the robot end-effector in Cartesian coordinates applicable to rehabilitation robotics or any other human-robot interactions such as haptic systems. The controller uses the parameters of a desired stable referencemodel which is the target impedance for the robot's end-effector. It also considers uncertainties in the model parameters of the robot. The asymptotic tracking is proven using Lyapunov stability theorem. Moreover, the adaptation law is proposed in joint space for reducing the complexity of its calculations;however, the controller and the stability proof are all presented in Cartesian coordinates. Using simulations and experiments on a two DOFs robot, the effectiveness of the proposed controller is investigated.
Due to the parametric and structural uncertainty of the DC drive system,an adaptivecontrol method is necessaryTherefore,an original model reference adaptive control(MRAC) for DC drives is proposed in this paperMRAC e...
详细信息
Due to the parametric and structural uncertainty of the DC drive system,an adaptivecontrol method is necessaryTherefore,an original model reference adaptive control(MRAC) for DC drives is proposed in this paperMRAC ensures on-line adjustment of the control parameters with DC machine parameter variationThe proposed adaptivecontrol structure provides regulating advantages:asymptotic cancellation of the tracking error,fast and smooth evolution towards the origin of the phase plan due to a sliding mode switching k-sigmoid functionThe referencemodel can be a real strictly positive function(the tracking error is also the identification error) as its order is relatively higher than one degreeFor this reason,the synthesis of the adaptivecontrol will use a different type of error called augmented or enhanced errorThe DC machine with separate excitation is fed at a constant fluxThis adaptivecontrol law assures robustness to external perturbations and to unmodelled dynamics
Four nonlinear modelreferenceadaptive Impedance controllers are introduced, tested, and compared for the control of the robot impedance with uncertainties in model parameters. The intended application area is human-...
详细信息
Four nonlinear modelreferenceadaptive Impedance controllers are introduced, tested, and compared for the control of the robot impedance with uncertainties in model parameters. The intended application area is human-robot interactions (HRI), particularly rehabilitation robots and haptic interfaces. All of the controllers make the closed-loop dynamics of the robot similar to the reference impedance model besides providing asymptotic tracking of the impedance model for the robot end-effector in Cartesian coordinates. The tracking and global stability are proved using Lyapunov stability theorem. Based on the simulations and experiments on a two-DOFs robot, the effectiveness of the proposed controllers is investigated. (C) 2014 Elsevier Ltd. All rights reserved.
This article investigates the problem of model reference adaptive control for a class of fractional order linear and nonlinear systems. Based on the fractional order tracking differentiator, the referencemodel adapti...
详细信息
ISBN:
(纸本)9781467360890
This article investigates the problem of model reference adaptive control for a class of fractional order linear and nonlinear systems. Based on the fractional order tracking differentiator, the referencemodeladaptivecontrol scheme is extended to the fractional order systems with the commensurate order 1 < α < 2. The stability of closed-loop control system is analyzed using frequency distributed model and Lyapunov stability theorem. Moreover, numerical simulations are performed to demonstrate the effectiveness of the proposed method.
The fast advancement of photovoltaic (PV) power generation technologies led to the integration of solar-based generation systems into several modes of transportation, including aircraft, automobiles, and trains. In th...
详细信息
The fast advancement of photovoltaic (PV) power generation technologies led to the integration of solar-based generation systems into several modes of transportation, including aircraft, automobiles, and trains. In these PV systems, solar irradiation levels fluctuate significantly and invalidate specific maximum power point (MPP) tracking (MPPT) control strategies, lowering the energy conversion efficiency. It is evident that the new robust model reference adaptive control (MRAC) proposed in this paper alleviates these problems by reducing tracking direction loss and oscillations near MPP. To evaluate the proposed controller's performance, MATLAB/Simulink is utilized and compared with well-known techniques (P&O, VSPO, INC, ANFIS, and swarm-based MPPT) under three different modes, i.e. stand-alone, grid-connected, and real-time mode. The proposed scheme has tracking efficacy lies between 99.02% and 99.96% and achieved MPP in just 4 msec under highly fluctuating radiation and temperature conditions. It takes only 0.08 sec to capture the global MPP, which is on average two times faster than swarm-based global MPPT methods. Furthermore, the effectiveness is tested in a 50 kW three-phase grid-connected mode with and without cloud effects in realistic weather situations. Finally, real-time validation on the OPAL-RT simulator demonstrates the proposed technique's practicality in real-world applications.
modelling and controlling of Continuous Stirred Tank Reactor (CSTR) is one of the significant problems in the process industry. Chemical reactions inside the CSTR depend on the reference value of the temperature. Desi...
详细信息
modelling and controlling of Continuous Stirred Tank Reactor (CSTR) is one of the significant problems in the process industry. Chemical reactions inside the CSTR depend on the reference value of the temperature. Design and implementation of suitable control device for such system is a challenge for researchers. This paper proposes the model reference adaptive control (MRAC) based control strategy as a solution to control problem of CSTR. An enhancement of Signal Synthesis MRAC scheme has been proposed in this study to improve the steady-state and transient-state performance of CSTR. Genetic Algorithm (GA) based controller parameter tuning method is employed to obtain the optimal performance of the controller. This paper presents the design and implementation of conventional Proportional-Integral-Derivative (PID) tuned with Ziegler-Nichols (ZN) tuning method, PID tuned with GA, MRAC, and GA-MRAC for CSTR. Detailed comparison based on simulation studies is also presented to show the improved transient and steady state response with GA-based improved MRAC scheme.
Improved power sharing can be achieved with the information of the impedances of a network. A modelreferenceadaptive system (MRAS) based scheme to estimate the effective line impedance as seen by the distributed gen...
详细信息
暂无评论