This paper describes a mathematical model for ferroresonant circuits that addresses some of the deficiencies of earlier analyses of ferroresonant regulators. Derived using piecewise-linear, normalized differential equations, the model accommodates nonlinear behavior and predicts circuit performance in terms of parameters such as line voltage, frequency, and load. A phase-plane analysis is used to simplify the determination of linear regions of operation between nonlinear events. Numerical solutions of the resulting equations are used to generate time-domain and parametric performance curves. The results compare well with experiments and suggest potential applications in the design of high-frequency voltage regulators.