Barbosa, Ramiro S.Machado, J. A. TenreiroVinagre, B. M.Calderón, A. J.2014-06-252014-06-2520071077-54631741-2986http://hdl.handle.net/10400.22/4576In this paper a modified version of the classical Van der Pol oscillator is proposed, introducing fractional-order time derivatives into the state-space model. The resulting fractional-order Van der Pol oscillator is analyzed in the time and frequency domains, using phase portraits, spectral analysis and bifurcation diagrams. The fractional-order dynamics is illustrated through numerical simulations of the proposed schemes using approximations to fractional-order operators. Finally, the analysis is extended to the forced Van der Pol oscillator.engFractional calculusVan der Pol oscillatorNonlinear oscillatorsFractional order operatorsjournal article10.1177/1077546307077463