Год выпуска: 2012 Автор: Hsin-I Hsu Издательство: LAP Lambert Academic Publishing Страниц: 128 ISBN: 9783847348023
Описание
A comprehensive and rigorous description of instantaneous balance of electromagnetic power defined as the derivative of energy with respect to time is offered by the Poynting’s theorem. Such theorem is expressed as the sum of a series of volume integrals representing the volume densities of densities of different components of electromagnetic power and the power flow through the general surface surrounding the entire domain in which the Poynting’s vector expresses the instantaneous power leaving the domain (the positive normal is the outward normal to the enclosing surface). For the moving points (rotors) involved in electromechanical energy conversion, the surface of integration is driven together with them and ? and ? remain substantially constant. Then the balance of energy (and power) can be written at each infinitesimal time interval for the electromagnetic energy in which case the elementary mechanical work is produced by mechanical forces of electromagnetic origin. The thermal...
