Research on a permanent magnet passively compensated pulsed alternator with ultra low mutual inductance research on a permanent magnet passively compensated pulsed alternator with ultra low mutual inductance
In this investigation, a permanent magnet passively compensated pulsed alternator (PMPCPA) with ultra low mutual inductance has been designed to provide an electrical pulse with the large power for the load in the shorter period. The electric excitation is replaced by the permanent magnet excitation, the passively compensated mode is adopted, and two-phase symmetrical windings with an electric angle difference of 90 degrees are respectively placed in the stator slots with both deep and shallow specifications to reduce the mutual inductance between the windings. On the basis of design scheme, the inductance of armature winding of alternator is calculated. Both noumenon and short circuit discharge models for the PMPCPA are established to perform the simulation, and the mutual inductance of PMPCPA is measured. The simulated and experimental results show that the present alternator can meet the design requirements, and the effectiveness of method for reducing the mutual inductance is verified.
Electromagnetic Analysis of a Permanent Magnet Compulsator (PMCPA)
The eddy current distribution in the shield of a new type CPA is discussed. In this new type CPA, permanent magnet is used to produce excitation field. Because of the permanent magnet, the working mode of this type CPA is different from the conventional CPA that using electric excitation. Therefore the discharge process and the action of the shield should be analyzed to design the parameters of the CPA. By making some assumptions, the problem of the electromagnetic field distribution can be simplified and an analytical solution of the two-dimensional diffusion equations can be obtained. The transient eddy current distribution in the shield and the forces on the armature during the discharge are discussed. Finite element method (FEM) is used and the results show that the conclusions from the analytical solution are basically correct and can be used for preparing and optimizing design data about later passive compulsators
Mesozoic rifting and basin inversion along the northern African Tethyan margin: an overview
Abstract The northern African Tethyan margin registered three major rifting episodes from the latest Palaeozoic-earliest Mesozoic to the earliest Cenozoic. Break-up of Gondwana was initiated in the late Carboniferous. Along the northern African-Arabian plate margin rifting propagated westward from the northeastern Arabian margin to Morocco during the Permian and Triassic, and was accompanied by Mid-Late Triassic-earliest Liassic extensive alkaline flow basalts. Rifting continued during the Liassic, e.g. in the Moghrebian Atlas troughs. A second stage of rifting occurred in the Late Jurassic and continued into, or was rejuvenated during, the Early Cretaceous. Along the east Mediterranean margin, some large E-W trending rifts formed, often with associated volcanism, e.g. southern Sirt and Abu Gharadig. Most researchers believe the oceanization of the eastern Mediterranean basin occurred at this time. Flexural subsidence affected the Moghrebian Atlas, including the Riffian-Tellian domain, where a thick flysch series was deposited. Two short-lived, but widespread and tectonically important, compressional or wrench-dominated events occurred during the Santonian and the latest Maastrichtian. From Morocco to Oman, most sedimentary basins were folded and inverted at these times. The Santonian event resulted from onset of the collision between the African-Arabian and Eurasian plates. New stress-fields favoured NE-SW extension along the African plate margin, generating or rejuvenating some rifts, e.g. in the Euphrates trough and in the Libya-Tunisia region (northwestern Sirt, Pelagian Sea). Rifting and magmatism continued in these regions into the Paleocene. During the Mesozoic, therefore, the northern margin of the African-Arabian plate registered both rifting resulting in the oceanization of the Tethys and rifting resulting from the initiation of the closure of the Tethys. The intraplate domain exhibited echoes of the tectonic events affecting the margin.