Electromagnetic actuators - Comparative performance

The classification criteria defined in "Electromagnetic actuators. Topological classifications". allow different actuators to be distinguished from a structural point of view. These criteria cover five areas:

• excitation source (synchronous motor, asynchronous motor, etc.) ;

• power winding (rotating field, global winding) ;

• other criteria related to magnetic sources (homopolar field, remote source);

• power supply (fixed-frequency power supply, mechanical switch, etc.) ;

• mechanical architecture (cylindrical or rotating structure, etc.).

The sheer diversity of architectures does not simplify the work of designers. When choosing a topology, many factors come into play. Some are directly imposed by the specifications:

• the nature of the movement (linear, rotary...) ;

• the number of actuator phases ;

• supply frequency (variable or fixed frequency) and control type (open or closed loop supply).

However, there are still many areas to be defined. These include the excitation source and the power winding. For these, the elements of comparison are :

• electromagnetic torque ;

• bulk or mass;

• actuator cost ;

• maximum rotation speed ;

• performance, etc.

Among these elements of comparison, electromagnetic torque (or force for linear actuators) and overall dimensions (or mass) play a key role in dimensioning. So we're going to draw up a simplified comparison between the different actuator families, based on these elements. In order to compare the torque performance of different electromagnetic actuators, we will establish similarity laws . These laws enable us to estimate the evolution of an actuator's performance as a function of a characteristic variable ${\mathcal{l}}^{\ast }$ . However, we would like to warn the reader that these analyses are more qualitative than quantitative in nature, and are therefore insufficiently precise....