A unified approach for stability analysis of a class of time-varying nonlinear systems

It is shown that an integral with negative feedback from its output terminal through a strictly passive system is still strictly passive. By using successive negative feedback around integrals, the conditions of strict passivity and a unified approach for constructing strictly passive systems are obtained for time-varying nonlinear systems of different orders. A new concept of "dissipation factor" is defined in this paper. The stability of a class of time-varying nonlinear systems is examined by using this passivity analysis.