Power and energy in linearized physical systems

Although no truly linear physical systems exist, linearized system models are very often used in practice to study the dynamics of real systems and components. Here, the relations between the power and energy in a non-linear physical system and the analogous quantities associated with variables representing small deviations from steady-state values are studied. Sometimes a linearized system is energetically similar to the non-linear system from which it was derived, and in other cases, new types of energy elements appear which were not present in the original system. In order to show the structure of the systems, the results are presented in both equation form and in the form of bond graphs which are unique in exhibiting the power and energy structure of system models.