Harmonic balance

Harmonic balance is a method used to calculate the steady-state response of nonlinear differential equations , and is mostly applied to nonlinear electrical circuits . It is a frequency domain method for calculating the steady state, as opposed to the various time-domain steady state methods. The name "harmonic balance" is descriptive of the method, which starts with Kirchhoff's Current Law written in the frequency domain and a chosen number of harmonics. A sinusoidal signal applied to a nonlinear component in a system will generate harmonics of the fundamental frequency. Effectively the method assumes the solution can be represented by a linear combination of sinusoids, then balances current and voltage sinusoids to satisfy Kirchhoff's law. The method is commonly used to simulate circuits which include nonlinear elements, and is most applicable to systems with feedback in which limit cycles occur.