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.
Investigation on the Current Pulse Formation of Compulsators
A compensated pulsed alternator is a special synchronous generator which is based on the law of electromagnetic induction and the law of flux compression. It is intentionally designed to maximize short circuit current output by minimizing internal impedance through the action of flux compression and air-core topology. It is an attractive compact high pulsed power supply which is composed of energy storage, energy conversion and pulse formation. In order to investigate the principle of compulsators and the pulse formatting current, the expression of pulsed current in three different compensation models is derived in detail, which is based on the simplified schematic and some assumptions. The main purpose of this paper is to analyze the factors which determined the pulsed power current waveforms. The selective passive compensated model is taken as an example for the analysis. The software MATLAB is used to calculate and draw the pulsed current waveform. Some typical pulsed current waveforms are obtained and then compared. The pulsed current waveform which is determined by many facts, such as the trigger angle, the relative position of winds, the coupling depth, the compensation model and so on, is analyzes. The waveform with and without compensation is also compared. Through the analysis of the pulse formatting current of compensated pulsed alternator, the relationship which is between the current pulse and the factors listed above is obtained. In the end, some conclusion is obtained by theory analysis,which is valuable for design of compensated pulsed alternators.
An Algorithm to Couple an External RL Circuit With the Finite-Element Code EMAP3D
Electromagnetic launch systems consist of pulsed power, rectification, and launch components. The finite-element (FE) code EMAP3D is used to compute the fields diffusing into sliding electrical contact launch components using quasi-static field equations. FE analysis of the entire launch system, though not impossible, would be a time-consuming process not worth the effort. Circuit theory based on lumped parameters is better suited for the analysis of some of the electrical components such as the generator, rectifier, power conditioning, and delivery components. Circuit theory becomes almost inevitable when one seeks to maximize the power delivered to launch components through impedance tuning techniques. Hence, one is inclined to look at ways of analyzing entire launch systems applying circuit theory to some components and FE analysis to others where detailed fields are required. An algorithm to couple an external circuit with an applied potential difference and prescribed resistances and inductances with a simple railgun is presented in this paper. The railgun is analyzed using EMAP3D. The external circuit is treated using circuit theory. Continuity of current and potentials is maintained through iterative calculations matching the currents and potentials between the circuit and the railgun. The advantages of this algorithm are that it treats the components using circuit theory and field theory separately and shows rapid convergence