Conditions For Optimal Efficiency Research Articles

Optimal efficiency condition and current reversals in forced underdamped ratchets

The condition of optimal efficiency in the energy transformation of a massive Brownian particle, moving in an asymmetric potential and subject to an external driving force, is studied by direct simulation of the stochastic differential equations. We analyze the behavior of the stationary averaged current and, at the same time, the energetic efficiency is evaluated. We found that the current exhibits several reversals when plotted as a function of the mass, and that it can be optimized at a particular value of the temperature. The condition to achieve an optimal efficiency is found, relating the mass, temperature and friction to the properties of the ratchet potential.

Models for induction machines with magnetic saturation of the main flux path

A novel nonlinear pi -model for an induction machine operating in magnetic saturation has been developed. It is based on a magnetic circuit model of a rotor-stator tooth pair, with nonlinear elements representing the saturation in the rotor and in the stator. The model of a tooth pair is extended to a model of the machine by assuming an infinite number of infinitesimal teeth. The model is compatible with the Blondel-Park transformation. Experimental measurements on a wound rotor machine confirm the model. Operating conditions for optimal efficiency at high torque levels requiring operation in saturation are computed with the model. >