LAI research activities

Small electromechanical and piezoelectric moving devices and their drives

Severe constraints imposed by device specifications (small volume, high efficiency, simplicity) require a device design optimization which combines a reliable optimization algorithm with a device mathematical model. As the optimization algorithm launches the mathematical model many times (order of thousands), a compromise between the speed and accuracy of the model should be achieved.

The moving device design in the LAI comprises the design of the corresponding electronic circuit and driving logic. In order to eliminate the rotor/mover position sensors, the LAI has developed algorithms which use the device electric quantities to estimate the position. Even more important, this fact is taken into account during the device design (“design for self-sensing”).

Contactless energy transfer

The principle of contactless energy transfer is simple: to supply a moving device containing a set of secondary coils using a set of primary ones (“air transformer”). The design of those systems is, however, always confronted with a relatively weak magnetic coupling (small mutual inductance) between the coils due to their variable mutual position and large air gaps.

In order to maximize the energy transfer and efficiency, special topologies of the primary and secondary electric circuits are used. The result of optimization procedure is the geometry of the coils and the electrical frequency. The supply logic is optimized to keep the required transferred energy and a maximal efficiency for any moving device position.