Experimental Investigation of Symmetry-Breaking in Ferroresonant Circuit

This study focuses on the impact of circuit parameters on the breaking of steady-state symmetry in a ferroresonant circuit. Symmetry-breaking occurs owing to pitchfork bifurcation and results in the ambiguousness of steady-state solution through two possible waveform types. The two types are distinguished in this study by positive and negative peak values of capacitor voltage. Circuit parameters analyzed in detail are source voltage RMS value U₁ and initial values of capacitor voltage and coil remanent flux. There is symmetry of occurrence in the two types of waveform, which is expected because of the odd symmetry of characteristics of all passive circuit elements. It is shown that the property of symmetry could be experimentally demonstrated and through simulation using a mathematical model of the experimental ferroresonant circuit. In addition, measurements have been carried out with two further coils to investigate the impact of the nominal voltage and type of core material on the initiation of the two types of waveforms.