Equivalent circuit

An equivalent circuit refers to a theoretical circuit that retains all of the electrical characteristics of a given device or motor. Often, an equivalent circuit is sought to simplify calculations. More broadly, it is the simplest form of a more complex circuit or a magnetic circuit in a motor, in order to aid analysis. Figure (a) is a useful steady-state equivalent circuit of a brush-type DC motor but can be applied to a brushless type when the winding inductance is negligible. Figure (b) is an expansion used for the analysis of dynamic responses.