scholarly journals An Active Control Design for a Class of Parametrically Excited Systems Based on the Gradient Algorithm

1998 ◽  
Vol 120 (3) ◽  
pp. 727-732
Author(s):  
Min-Shin Chen ◽  
Ren-Jay Fu
Keyword(s):  
Control Design ◽  
Open Loop ◽  
Observer Design ◽  
State Feedback Control ◽  
Gradient Algorithm ◽  
System Stability ◽  
System Matrix ◽  
Variation Of Parameters ◽  
Present Information ◽  
Null System

This paper introduces a new control design for a dynamic system subject to stationary or nonstationary parametric excitations. In this new design, the system dynamics is transformed into one with a null system matrix using the variation of parameters method. A stabilizing state feedback control can then be immediately obtained by following the gradient algorithm that is originally developed for the parameter identification purpose. Such a design has the advantage that the control requires only past and present information of the time-varying parametric excitations while previous control designs usually require prediction of future information of the excitations. The closed-loop system stability is guaranteed if the open-loop state response does not diverge too fast. The control design approach can also be applied to the observer design in case where there is only partial observation of the system state.

fuzzy state-feedback control design for nonlinear systems with -stability constraints: An LMI approach

2008 ◽  
Vol 78 (4) ◽  
pp. 514-531 ◽  
Author(s):  
Wudhichai Assawinchaichote ◽  
Sing Kiong Nguang ◽  
Peng Shi ◽  
El-Kébir Boukas
Keyword(s):  
Feedback Control ◽  
Nonlinear Systems ◽  
State Feedback ◽  
Control Design ◽  
State Feedback Control ◽  
Lmi Approach ◽  
Fuzzy State

scholarly journals Grid-Forming Control Suitable for Large Power Transmission System Applications

2021 ◽  
Author(s):  
Taoufik QORIA ◽  
Xavier Guillaud
Keyword(s):  
Power Transmission ◽  
Stability Margin ◽  
Open Loop ◽  
System Stability ◽  
Test Cases ◽  
Large Power ◽  
Control Loops ◽  
Power Inverters ◽  
Practical Feasibility ◽  
Typical Solution

The inner cascaded structure-based grid-forming control is a typical solution used to impose an AC voltage magnitude across the output filters of the power inverters. Yet, because of the limited inverter’s bandwidth resulting from the low-switching frequencies in transmission systems, the interaction (i.e., coupling) between control loops is highly likely making the understanding of the system behavior complex and its simplification unaffordable and may also lead to instabilities. The novelty of this paper consists in proposing a simple open-loop direct voltage control to reduce the number of the inner control regulators, and thereby guaranteeing a decoupling between the inner and outer control layers as well as increasing the system stability margin. This statement is well supported with a small-signal analysis and progressive order model reduction of the system. The overall concept is validated in a 10-bus grid case while comparing the EMT and Phasor-based simulations. The practical feasibility of the control itself is experimentally proved with different test cases.

Bifurcation Analysis of Ship Steering in Canals

2003 ◽  
Vol 46 (02) ◽  
pp. 92-100
Author(s):  
Fotis A. Papoulias ◽  
Panos E. Kapasakis
Keyword(s):  
Bifurcation Analysis ◽  
Complete System ◽  
Equations Of Motion ◽  
Open Loop ◽  
System Stability ◽  
Control Law ◽  
Time Lags ◽  
Essential Dynamics ◽  
Ship Steering ◽  
Loop Dynamics

The problem of ship steering in canals and confined waters is analyzed with emphasis on stability and bifurcation analysis. The classical maneuvering equations of motion augmented with a model for ship-canal interaction are used to model open-loop dynamics. Coupling of a control law and a guidance scheme with appropriate time lags is employed to model the essential dynamics of a helmsman. The complete system is analyzed using both linear and nonlinear techniques in order to assess its stability under finite disturbances. The results indicate that for certain regions of parameters, limit cycle oscillations may develop that could compromise system stability and safety of operations.

The Motor Active Flexible Suspension and Its Dynamic Effect on the High-Speed Train Bogie

2017 ◽  
Vol 140 (6) ◽  
Author(s):  
Yuan Yao ◽  
Yapeng Yan ◽  
Zhike Hu ◽  
Kang Chen
Keyword(s):  
Control System ◽  
Time Delay ◽  
High Speed ◽  
State Feedback ◽  
State Feedback Control ◽  
System Stability ◽  
High Speed Train ◽  
Suspension Parameters ◽  
Linear And Nonlinear ◽  
Hunting Stability

We put forward the motor active flexible suspension and investigate its dynamic effects on the high-speed train bogie. The linear and nonlinear hunting stability are analyzed using a simplified eight degrees-of-freedom bogie dynamics with partial state feedback control. The active control can improve the function of dynamic vibration absorber of the motor flexible suspension in a wide frequency range, thus increasing the hunting stability of the bogie at high speed. Three different feedback state configurations are compared and the corresponding optimal motor suspension parameters are analyzed with the multi-objective optimal method. In addition, the existence of the time delay in the control system and its impact on the bogie hunting stability are also investigated. The results show that the three control cases can effectively improve the system stability, and the optimal motor suspension parameters in different cases are different. The direct state feedback control can reduce corresponding feed state's vibration amplitude. Suppressing the frame's vibration can significantly improve the running stability of bogie. However, suppressing the motor's displacement and velocity feedback are equivalent to increasing the motor lateral natural vibration frequency and damping, separately. The time delay over 10 ms in control system reduces significantly the system stability. At last, the effect of preset value for getting control gains on the system linear and nonlinear critical speed is studied.

scholarly journals Variable structure observer design for a class of uncertain systems with a time-varying delay

2012 ◽  
Vol 22 (3) ◽  
pp. 575-583 ◽  
Author(s):  
Wen-Jeng Liu
Keyword(s):  
Uncertain Systems ◽  
Sliding Mode ◽  
Variable Structure ◽  
Observer Design ◽  
State Feedback Control ◽  
Invariance Property ◽  
Time Varying ◽  
Time Varying Delay ◽  
Error System ◽  
Varying Delay

Abstract Design of a state observer is an important issue in control systems and signal processing. It is well known that it is difficult to obtain the desired properties of state feedback control if some or all of the system states cannot be directly measured. Moreover, the existence of a lumped perturbation and/or a time delay usually reduces the system performance or even produces an instability in the closed-loop system. Therefore, in this paper, a new Variable Structure Observer (VSO) is proposed for a class of uncertain systems subjected to a time varying delay and a lumped perturbation. Based on the strictly positive real concept, the stability of the equivalent error system is verified. Based on the generalized matrix inverse approach, the global reaching condition of the sliding mode of the error system is guaranteed. Also, the proposed variable structure observer will be shown to possess the invariance property in relation to the lumped perturbation, as the traditional variable structure controller does. Furthermore, two illustrative examples with a series of computer simulation studies are given to demonstrate the effectiveness of the proposed design method.

A Novel Digital Speed Control Design for Brushless DC Motor Drives

2017 ◽  
Author(s):  
Wei Wu ◽  
Xin Wang ◽  
Andy G. Lozowski
Keyword(s):  
Control Design ◽  
Speed Control ◽  
Dc Motor ◽  
System Stability ◽  
Brushless Dc Motor ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Gain Margin ◽  
Dc Motor Drives ◽  
Computer Numerical Simulation

This paper presents a novel robust digital speed control design for brushless DC motors (BLDCs). The speed control can be achieved by regulating the DC link voltage of a six-step inverter. The discrete-time brushless DC motor dynamics is derived through bilinear transform. A robust digital control algorithm is designed to guarantee the closed loop system stability by satisfying the desired phase and gain margin. Computer numerical simulation studies and hardware implementation have demonstrated the effectiveness and robustness of the proposed scheme.

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