Equivalent Models of Nonlinear Circuit Elements in Nonsinusoidal Regime

The circuits containing voltage or charge controlled nonlinear capacitors (qc), or current or flux controlled nonlinear inductors (cc), or current or voltage controlled nonlinear resistors can be simulated using the dedicated software SPICE by developing equivalent models for these circuit elements. Using macro-models, with equivalent schemes which model the voltage or current sources controlled by the time derivatives of the voltage and current respectively, this paper described all types of nonlinear circuit elements, in SPICE, with the corresponding sub-circuits. These sub-circuits allow the simulation of these circuits in time domain, using either SPICE or Symbolic State Equation Generation (SYSEG) programs. Then, by using the FFT function form MATLAB's toolbox, the circuits were analyzed in frequency domain, to underline the currents, the voltages and the harmonic spectrum which present interest.