Stationary modes and their possible bifurcations in nonautonomous electrical circuits with nonlinear resistive elements, the voltage-current characteristic of which cannot be satisfied to known conditions of convergence, are investigated. The main result of this article is description of current modes in a single and three-phase circuit with asymmetric voltage-current characteristics. The most interesting result of investigation of these transient and steady current modes in nonlinear electrical circuits is the possibility of the quasi-periodical process with low-frequency component, values and significance of which can be modulated by modification of amplitude of external high-frequency three-phase voltage.