Noves aportacions al desenvolupament de motors elèctrics sense coixinets.

Resumo

Our idea is to rotate pipes produced of conductor materials (copper or aluminium) having different lengths and diameters. The pipe to be rotated is secondary in an induction electrical device and acts as rotor, or mobile part. The inductor of the device, acting as stator or fixed part, is powered by means of an ideal current source. Therefore we deal with an electical system powered by a current source, in contrast to usual electrical systems powered by means of a voltage source. In an electrical system powered by a current source, the terminal power is obtained by varying the voltage applied to the device, the current being fixed. One should avoid open circuits similar to avoiding short circuits in a system powered by a voltage source. This work fits into a wider framework which, using new materials (ferrite, superconductors, electronics), puts into question the whole essense of electrical devices. The results obtained are as expected by other authors who follow parallel and complementary ways. The possibility of using these new devices in textil applications is considered. Constructively, we work with an only conductor per slot. This enables one to replace segments of rigid conductor by superconductors in our devices. The inductor conductors are water-cooled in order to increase the current density. When superconductors are used, cooling by liquid nitrogen will be required. The working method is experimental; however, other tools are not discarded (theoretical adjustments, simulations using the finite elements). We begin with designing a first prototype to meet the only two restrictions: maximum simplicity and powering by a current source. This is the so-called canedevice, or Prat-1. The results obtained enable us to design two new prototypes. Two variants of each of these prototypes are made. The first is a stator sector device. The inductor of this device is the one and only stator arc (Prat- 2.1). A complete model is a device containing eighty conductors (Prat-2.0). Pneumatic prototypes of the both devices are made and tested. The electromagnetic part of Prat-2.1 is also studied. The next step is to construct a device which starts by reluctance variation, if powered in monophase, and by rotary camp, if powered in biphase. This is the reluctance started device (Prat-3).Another version of this device is constructed using fused tin (which, by means of appropriate tools, fills in the routes designed for the electic circuit). This is the so-called tin-filled device (Prat-4). In industrial applications, tin is suggested to be replaced by aluminium. Both devices have eight water-cooled copper conductors. All above results enable us to construct a three-phase device having an external rotor and two inductors (Prat-5). These prototypes rotate without mechanical bearings. In case of Prat-2.0/ Prat-2.1, a pneumatic bearing is used. In the cane device, a rotor axial displacement towards outside is observed when the current is increased. The remaining three prototypes rotate without bearings proving to have frictions of minor importance. We do not deal with the topic of levitation related to these phenomena, since our basic focus in this work has been rather on constructive aspects. Let us indicate as the most significant facts that we have worked with the only conductor per slot, that symmetries are of an utmost importance for designing these devices, that an intensity transformator is required for the device, and that we are sure that there should be a tendency towards more and more plain slots. The cane device having no slots (a pure current layer) is the one that rotates better and, moreover, levitates.