scholarly journals Fractional Describing Function Analysis of PWPF Modulator

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Xinsheng Wang ◽  
Danwei Wang ◽  
Senqiang Zhu ◽  
Eng Kee Poh
Keyword(s):  
Phase Shift ◽  
Fractional Order ◽  
Pulse Width ◽  
Function Method ◽  
Function Analysis ◽  
Pulse Frequency ◽  
Describing Function ◽  
Nonlinear Properties ◽  
Describing Function Method ◽  
Effective Analysis

Pulse-width pulse-frequency (PWPF) modulators are widely used in spacecraft thruster control. Their dynamic characteristic is still lack of effective analysis tools. This paper presents a fractional describing function method to describe the frequency characteristics of PWPF. A frequency-dependent gain and phase shift are clearly described by fractional-order expression, and the fractional-order behaviors depict the nonlinear properties of PWPF modulators. This fractional describing function method can also be applied to other kinds of modulators.

Analysis of a fractional order Van der Pol-like oscillator via describing function method

2010 ◽  
Vol 61 (1-2) ◽  
pp. 265-274 ◽  
Author(s):  
Mina Attari ◽  
Mohammad Haeri ◽  
Mohammad Saleh Tavazoei
Keyword(s):  
Fractional Order ◽  
Function Method ◽  
Describing Function ◽  
Van Der Pol ◽  
Describing Function Method

CHAOTIC BEHAVIOR IN A FRACTIONAL-ORDER SYSTEM CONTAINING A CONTINUOUS ORDER-DISTRIBUTION

2012 ◽  
Vol 22 (10) ◽  
pp. 1250253 ◽  
Author(s):  
TOM T. HARTLEY ◽  
CARL F. LORENZO
Keyword(s):  
Nonlinear System ◽  
Fractional Order ◽  
Function Method ◽  
Chaotic Behavior ◽  
Order System ◽  
Fractional Dynamics ◽  
Approximation Methods ◽  
Describing Function ◽  
Describing Function Method ◽  
Bifurcation Behavior

This paper discusses the fractional dynamics, and the bifurcation behavior, of a specific nonlinear system that contains a continuous order-distribution. The dynamics of the system are predicted using the describing-function method. General approximation methods are then derived for the continuous order-distribution component. The system is simulated using these approximations, and the results compared with the describing-function predictions. This is believed to be the first observation of chaos in a system with continuous order-distribution.

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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