Analysis of the Two-Coil Model of the Ferroresonant Transformer with a Rectified Output in the Low-Line Heavy-Load Minimum-Frequency Condition

Most of the previous analyses of the ferroresonant transformer have been for the unrectified-output ac-load circuit, and do not include some or all of the important stray loss mechanisms. This paper focuses on the rectified-output dc-load case and includes the stray losses. The low-line heavy-load minimum-frequency condition is the worst-case condition for supplying power to the load. The ferroresonant transformer is modeled by its two-coil equivalent circuit. Analysis is simplified by assumptions about the operation of the circuit in this worst-case condition. A time integration of the nonlinear differential equations that characterize the two-coil model determines the steady-state dc and rms circuit voltages and currents as a function of the circuit component values. The general operating characteristics of the transformer are determined by observing the variation of the circuit voltages and currents as the circuit component values are varied. Using that technique, it is possible to specify which component values yield a design in which the transformer winding currents are at a minimum and the input power factor and conversion efficiency are at a maximum.