scholarly journals Optimal Robust LQI Controller Design for Z-Source Inverters

2020 ◽  
Vol 10 (20) ◽  
pp. 7260
Author(s):  
Amirhossein Ahmadi ◽  
Behnam Mohammadi-Ivatloo ◽  
Amjad Anvari-Moghaddam ◽  
Mousa Marzband
Keyword(s):  
Disturbance Rejection ◽  
Controller Design ◽  
Design Procedure ◽  
Bat Algorithm ◽  
Linear Quadratic ◽  
System A ◽  
Stability Robustness ◽  
Power Inverters ◽  
Quadratic Integral ◽  
The Stability

This paper investigates the linear quadratic integral (LQI)-based control of Z-source inverters in the presence of uncertainties such as parameter perturbation, unmodeled dynamics, and load disturbances. These uncertainties, which are naturally available in any power system, have a profound impact on the performance of power inverters and may lead to a performance degradation or even an instability of the system. A novel robust LQI-based design procedure is presented to preserve the performance of the inverter against uncertainties while a proper level of disturbance rejection is satisfied. The stability robustness of the system is also studied on the basis of the maximum sensitivity specification. Moreover, the bat algorithm is adopted to optimize the weighting matrices. Simulation results confirm the effectiveness of the proposed controller in terms of performance and robustness.

Discrete-Time Repetitive Control System Design Using the Regeneration Spectrum

1993 ◽  
Vol 115 (2A) ◽  
pp. 228-237 ◽  
Author(s):  
F.-R. Shaw ◽  
K. Srinivasan
Keyword(s):  
Control Systems ◽  
Discrete Time ◽  
System Performance ◽  
Controller Design ◽  
Repetitive Control ◽  
Design Procedure ◽  
Controlled System ◽  
Stability Robustness ◽  
Analysis And Synthesis ◽  
The Stability

The stability, transient response, and stability robustness of discrete-time repetitive control systems characterized by large values of the time delay inherent in such systems are examined here using a function of frequency termed the regeneration spectrum. The ability to infer different aspects of controlled system performance from the regeneration spectrum, and its ease of computation, makes it a valuable tool for controller analysis and synthesis. A design procedure for discrete-time repetitive control systems, based on the regeneration spectrum, is outlined and a controller form suggested to effectively handle the trade-off between the different aspects of controlled system behavior. The controller design procedure is applied to an electrohydraulic material testing application characterized by strong nonlinearities, and shown experimentally to be effective in improving the controlled system performance.

Stability and robustness for discrete-time systems with control signal saturation

2000 ◽  
Vol 214 (1) ◽  
pp. 65-76 ◽  
Author(s):  
A R Plummer ◽  
C S Ling
Keyword(s):  
Discrete Time ◽  
Controller Design ◽  
Control Signal ◽  
Design Stage ◽  
System Control ◽  
Stability Robustness ◽  
Discrete Time Systems ◽  
The Stability ◽  
Time Systems ◽  
Signal Saturation

All practical control systems exhibit control signal saturation. The effect that this saturation has on the control system performance, especially stability and robustness, can be significant and must be understood at the controller design stage. This paper presents conditions for global asymptotic stability and measures of stability robustness for such systems. These are demonstrated through simulation examples, and it is shown how an understanding of the stability conditions can inform the controller design process. The off-axis circle criterion is used as the basis for a sufficient condition for stability, and it is argued that this is not overly restrictive in practice. The derivations are carried out in discrete time, and servo-system control is envisaged as an important application area for the techniques; however, the results are applicable more widely.

Stability Robustness of LQ and LQG Active Suspensions

1994 ◽  
Vol 116 (1) ◽  
pp. 123-131 ◽  
Author(s):  
A. G. Ulsoy ◽  
D. Hrovat ◽  
T. Tseng
Keyword(s):  
Controller Design ◽  
Active Suspension ◽  
Point Of View ◽  
Linear Quadratic ◽  
Linear Quadratic Gaussian ◽  
Active Suspensions ◽  
Quarter Car Model ◽  
Stability Robustness ◽  
Trade Offs ◽  
Two Degree Of Freedom

A two-degree-of-freedom quarter-car model is used as the basis for linear quadratic (LQ) and linear quadratic Gaussian (LQG) controller design for an active suspension. The LQ controller results in the best rms performance trade-offs (as defined by the performance index) between ride, handling and packaging requirements. In practice, however, all suspension states are not directly measured, and a Kalman filter can be introduced for state estimation to yield an LQG controller. This paper (i) quantifies the rms performance losses for LQG control as compared to LQ control, and (ii) compares the LQ and LQG active suspension designs from the point of view of stability robustness. The robustness of the LQ active suspensions is not necessarily good, and depends strongly on the design of a backup passive suspension in parallel with the active one. The robustness properties of the LQG active suspension controller are also investigated for several distinct measurement sets.

LQG-Based Robustifying Flight Control System

2003 ◽  
Author(s):  
D. Griffin ◽  
A. G. Kelkar
Keyword(s):  
Control System ◽  
Flight Control ◽  
Controller Design ◽  
Second Step ◽  
Flight Control System ◽  
Robust Controller ◽  
Fighter Aircraft ◽  
Stability Robustness ◽  
Uncertainty Model ◽  
The Stability

This paper presents a robust controller design for an automatic flight control system (AFCS) for a fighter aircraft model with eight inputs and seven outputs. The controller is designed based on McFarlane-Glover robustifying technique using a simple baseline LQG design. Controllers designed purely based on traditional LQG techniques are known to have no guaranteed robustness margins. The McFarlane-Glover technique can be used to enhance the stability robustness of the baseline LQG design using a two-step design process. In the first step, an LQG controller is designed which is optimized only for performance without any consideration to robustness. In the second step, the performance optimized LQG design is rendered robust using McFarlane-Glover procedure. The robustifying procedure uses a coprime factor uncertainty model and H∞ optimization. An important advantage of this procedure is that no problem dependent uncertainty modelling or weight selection is required in the second step of the process. The robustifying procedure also yields the quantitative estimate of the robustness.

A Linear Quadratic Integral Design Approach for the Automatic Control System of a Launch Vehicle

2015 ◽  
Vol 772 ◽  
pp. 410-417 ◽  
Author(s):  
Adrian Mihail Stoica ◽  
Cristian Emil Constantinescu ◽  
Silvia Nechita
Keyword(s):  
Control System ◽  
Flight Control ◽  
Launch Vehicle ◽  
Design Approach ◽  
Flight Control System ◽  
Linear Quadratic ◽  
Atmospheric Disturbances ◽  
Modeling Uncertainties ◽  
Quadratic Integral ◽  
The Stability

This paper presents a design approach for the automatic flight control system of a launch vehicle using a linear quadratic integral technique together with a fixed gain Kalman filter. Its purpose is to analyse the stability and tracking robustness performances of the control system designed via this approach when atmospheric disturbances, modeling uncertainties and structural flexible modes of the launcher are taken into account.

scholarly journals LQR/Sliding Mode Controller Design Using Particle Swarm Optimization for Crane System

2020 ◽  
Vol 23 (1) ◽  
pp. 45-50
Author(s):  
Hazem Ali ◽  
Azhar Jabbar Abdulridha ◽  
Rawaa Khaleel ◽  
Kareem Kareem A. Hussein
Keyword(s):  
Particle Swarm Optimization ◽  
Controller Design ◽  
Sliding Mode ◽  
External Disturbance ◽  
Particle Swarm ◽  
Design Procedure ◽  
Linear Quadratic Regulator ◽  
Linear Quadratic ◽  
Swarm Optimization ◽  
Highly Nonlinear

In this work, the design procedure of a hybrid robust controller for crane system is presented. The proposed hybrid controller combines the linear quadratic regulator (LQR) properties with the sliding mode control (SMC) to obtain an optimal and robust LQR/SMC controller. The crane system which is represented by pendulum and cart is used to verify the effectiveness of the proposed controller. The crane system is considered one of the highly nonlinear and uncertain systems in addition to the under-actuating properties. The parameters of the proposed LQR/SMC are selected using Particle Swarm Optimization (PSO) method. The results show that the proposed LQR/SMC controller can achieve a better performance if only SMC controller is used. The robustness of the proposed controller is examined by considering a  variation in system parameters with applying an external disturbance input. Finally, the superiority of the proposed LQR/SMC controller over the SMC controller is shown in this work.

Step Output Tracking Controller Design for Networked Control Systems

2013 ◽  
Vol 17 (6) ◽  
pp. 813-817
Author(s):  
Zhong-Hua Pang ◽  
◽  
Guo-Ping Liu ◽  
Donghua Zhou ◽  
◽  
...  
Keyword(s):  
Controller Design ◽  
Networked Control Systems ◽  
Design Procedure ◽  
Packet Dropout ◽  
Output Tracking ◽  
Trip Time ◽  
Control Scheme ◽  
Tracking Controller ◽  
Networked Predictive Control ◽  
The Stability

This paper is concerned with the step output tracking controller design problem for networked discretetime linear systems. The communication constraints such as network-induced delay, packet disorder, and packet dropout are considered, which are treated as the round-trip time (RTT) delay with an upper bound. An event-driven networked predictive control scheme is proposed to actively compensate for the RTT delay, which avoids the requirement of synchronization between the controller side and the plant side. The stability of the closed-loop system and the design procedure of the observer-based controller are discussed. A numerical example is employed to illustrate the effectiveness of the proposed methods.

Stability Analysis and Controller Design for Fuzzy Parameter Varying Systems Based on Fuzzy Lyapunov Function

2018 ◽  
Author(s):  
Xiaojun Ban ◽  
Hongyang Zhang ◽  
Fen Wu
Keyword(s):  
Lyapunov Function ◽  
Controller Design ◽  
Design Procedure ◽  
Handling Time ◽  
Feedback Gain ◽  
Time Varying ◽  
System A ◽  
Fuzzy Lyapunov Function ◽  
Parameter Varying ◽  
Fuzzy Parameter

The fuzzy parameter varying (FPV) system is a mathematical model proposed to handle nonlinear time-varying dynamical systems encountered in engineering, which has some essential advantages in handling time-varying models. In this article, a new relaxation approach is proposed for the analysis and controller design of the FPV system. Different from the current results on the FPV system, the proposed approach employs the fuzzy Lyapunov function and full block S-procedure to reduce the conservatism in analysis. Furthermore, the relaxation technique proposed in this article can be also used in solving controller synthesis problem effectively. As a result, a design procedure of non-PDC output feedback gain-scheduling controller is provided to ensure asymptotic stability of the closed-loop FPV system. A numerical example is provided to illustrate the proposed method.

Bounded-Input-Bounded-Output Stability of Nonlinear Feedback Systems in a Volterra Representation

2000 ◽  
Author(s):  
John W. Glass ◽  
Matthew A. Franchek
Keyword(s):  
Stability Condition ◽  
Closed Loop ◽  
Controller Design ◽  
External Disturbance ◽  
Design Procedure ◽  
Nonlinear Feedback ◽  
Feedback Systems ◽  
Volterra Kernels ◽  
The Stability ◽  
Nonlinear Feedback Systems

Abstract Presented in this paper is a stability condition for a class of nonlinear feedback systems where the plant dynamics can be represented by a finite series of Volterra kernels. The class of Volterra kernels are limited to p-linear stable operators and may contain pure delays. The stability condition requires that the linear kernel is nonzero and that the closed loop characteristic equation associated with the linearized system is stable. Next, a sufficient condition is developed to upper bound the infinity-norm of an external disturbance signal thereby guaranteeing that the internal and output signals of the closed loop nonlinear system are contained in L∞. These results are then demonstrated on a design example. A frequency domain controller design procedure is also developed using these results where the trade-off between performance and stability are considered for this class of nonlinear feedback systems.

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