Anti-Windup Control of Second-Order Plants With Saturation Nonlinearity

1993 ◽  
Vol 115 (4) ◽  
pp. 715-720 ◽  
Author(s):  
Ming C. Leu ◽  
Sangsik Yang ◽  
Andrew U. Meyer
Keyword(s):  
Control System ◽  
Control Systems ◽  
Real World ◽  
System Performance ◽  
Function Method ◽  
Second Order ◽  
Describing Function ◽  
Saturation Nonlinearity ◽  
Integral Action ◽  
Describing Function Method

All real-world control systems have saturation nonlinearity in final control elements (including actuators). When controllers involve integral action, reset windup can cause instability as well as make system performance unsatisfactory. Based on the describing function method and the generalized Popov criterion, this paper presents analysis of the global stability of a control system having a saturating second-order plant, both with and without using a deadbeat limiting scheme to constrain its controller output. The improvement of system performance by incorporating the anti-windup feature in the controller is illustrated by computer simulations.

Harmonic Loss Calculation of Three-Phase Transformer Based on J-A Model

2013 ◽  
Vol 325-326 ◽  
pp. 519-524
Author(s):  
Lian Liu ◽  
Qiong Lin Li ◽  
Hui Jin Liu ◽  
Xue Cui ◽  
Lei Zou
Keyword(s):  
Maxwell Equations ◽  
Function Method ◽  
Domain Model ◽  
Iron Core ◽  
Describing Function ◽  
Good Convergence ◽  
Proposed Model ◽  
Three Phase ◽  
Describing Function Method ◽  
Transformer Model

Beginning with characterizing the nonlinearities of transformer, this paper uses the J-A model to represent the hysteresis of iron core, and fits the model in calculating exciting current. Compared with the other methods, such as polynomial and describing function method, J-A model is more capable in representing nonlinearity, so the calculated current would be more accurate. Then, after analyzing Maxwell equations that meet certain boundary conditions, the paper considers comprehensively the effects of skin and proximity, and then obtains the computing way of ac resistance under harmonics. At last, based on the mentioned results, paper proposes a set of three-phase transformer model which could calculate harmonic losses. The proposed model is a kind of combined time-and frequency-domain model that possesses good convergence. The introduced example has verified the correctness and effectiveness of the model which absolutely suits the engineering applications.

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