Impedance of nonlinear current or voltage dependent devices
ABSTRACT: Many real devices such as batteries are nonlinear and their impedance values depend on either current or voltage. However, impedance analysis is based on the assumption of a linear system. If certain conditions such as sufficiently small excitation amplitude to ensure quasi-linearity and measurements at several operating points are fulfilled, also the impedance of a nonlinear system can be interpreted. Equations to calculate the large signal impedance from small signal impedance measurements of current, voltage and mixed dependent devices are derived and analyzed.