Rotating machines: electromechanical energy conversion

Ever since the advent of the first operational electromechanical energy conversion devices, the field of application for electrical machines has been constantly expanding, and this trend underwent a veritable explosion in the last quarter of the twentieth century. Indeed, in addition to the development of traditional electrical applications based on motors or generators (rail traction, power generation, rolling mills...), it is more generally within modern electrical systems that electromechanical actuators and sensors now find their most innovative outlets [automotive equipment: for example, a 1968 Citroën DS 21 "Pallas" has fewer than 10 electromechanical actuators (mostly commutator motors), while an XM V6 "Exclusive" from the 1990s has more than 50 (not including relays), 30 of which are assigned to engine control functions; avionics; office automation; home automation...]. So, while for a long time the use of the possibilities offered by electricity consisted in "adapting" generic solutions (the "universal" motor is a particularly clear illustration of this philosophy), the diversification of needs and the performance required, in the face of the technological challenges of the moment (aeronautics and space, high-speed trains, microsurgery...), are breathing new life into the field of electro-mechanical machines and actuators: the function now specifically induces the component. This pattern takes on a particularly acute meaning in the age of "microsystems", whose success is based on the submillimeter-scale integration of actuators and sensors designed and operated collectively.

This article provides an overview of the different technological solutions available today. While an exhaustive presentation of the structures currently in use remains relatively illusory, the aim of the presentation is to highlight the basic concepts on which the design of modern machines and actuators is based. In this first booklet, after setting out the general energy formalism that characterizes electromechanical energy transformation from a phenomenological point of view, the various physical phenomena likely to contribute to this transformation are logically introduced.

The article "Rotating electrical machines. Electromechanical energy conversion" is the subject of two booklets:

D 3 410 Rotating machines: electromechanical energy conversion.

D 3 411 Rotating machines: principles and construction.

The subjects are not independent of each other.

Readers will need to refer to the other booklet often enough.