Unstable Phenomena in a Two-Phase Nonlinear Circuit

A ferroresonant-based two-phase circuit functions as a parametric oscillator, and is widely used in various kinds of power devices. When the load conductance of the circuit is very small, the parametric oscillations occurring in the circuit become unstable. It has been reported that the occurrence of unstable oscillations is due to the resistance of the power supply side of the circuit. When the magnetization curve of the circuit reactor has a sharp saturation characteristic, unstable oscillations differing from the above-mentioned mode occur in the first circuit (load side) of the two-phase circuit. This paper clarifies the relationship between the unstable state of the circuit and the nonlinearity of the magnetization curves of the cores used in the circuit, and confirms experimentally the validity of the analysis.