In the paper linear time-invariant difference equations are applied to model dynamic systems. The forward difference with higher fractional-order is used. Admitting fractional-orders of systems, we gather a better modelling of the inductive and capacitive couplings in the electrical circuit. The investigations are illustrated by numerical examples with real simple electrical circuit and electrical circuit with DC micromotor and supercapacitors modelling.
The fractional calculus is the area of mathematics that handles derivatives and integrals of any arbitrary order (fractional or integer, real or complex order) [1,2,3,4]. Nowadays it is applied in almost all areas of science and engineering. Here one can mention its numerous and successful applications in dynamical systems modeling and control with increasing number of studies related to the theory and application of fractional-order controllers, specially ones. In such controllers μ k <;0 and v k >; 0 denote the integration and differentiation order, respectively. Now research activities are focused on developing new analysis and closed-loop system synthesis methods for fractional-order controllers being an extension of classical control theory. In the fractional-order controller tuning there are two additional parameters μ k <; 0 and v k >; 0. This impedes the controller tuning procedure but leads to new (unattainable in classical PID control [5]) closed-loop system transient responses. The closed-loop system with fractional controller must satisfy typical requirements among which one can mention the system robustness due to the plant model uncertainties.
There were investigated some particular properties of variable-, fractional-order backward differences (VFOBD). The most of proved properties are connected with coefficients of VFOBD. There are presented examples of the numerical results of VFOBD.
Abstract In this paper the authors present highly accurate and remarkably efficient computational methods for fractional order derivatives and integrals applying Riemann-Liouville and Caputo formulae: the Gauss-Jacobi Quadrature with adopted weight function, the Double Exponential Formula, applying two arbitrary precision and exact rounding mathematical libraries (GNU GMP and GNU MPFR). Example fractional order derivatives and integrals of some elementary functions are calculated. Resulting accuracy is compared with accuracy achieved by applying widely known methods of numerical integration. Finally, presented methods are applied to solve Abel’s Integral equation (in Appendix).