Search results

A feasibility study for a large power transformer reveals several key design issues, each of which is expressible in terms of simple, fundamental field effects. Six generic effects are briefly reviewed and their importance explained. In all cases but one their influence can be estimated, to an accuracy adequate for feasibility purposes, without computation or detailed analysis. They are: mechanical stress due to magnetic fields; electrical breakdown caused by winding capacitance distribution; dielectric breakdown caused by the mixing of different materials, including liquid nitrogen; reduction of critical current density due to internal magnetic fields; the need, or otherwise, for conductor transposition; modelling of field penetration and ac losses in HTc superconductors.

The purpose of this paper is to find effective methods of loop analysis of multi‐branch and multi‐node non‐linear circuits using a singular formulation.

The classical loop analysis and the loop analysis using a singular formulation have been compared. The non‐linear systems of equations have been considered and iterative procedures of solving non‐linear equations have been applied. Special attention has been paid to the Newton‐Raphson method combined with successive over relaxation and incomplete Cholesky conjugate gradient methods. The convergence of the methods has been discussed.

It has been shown that in the case of the loop analysis of non‐linear circuits it is not necessary to form fundamental loops. The system of loop equations with a singular coefficient matrix can be successfully solved iteratively. Using a singular formulation one of the infinitely many solutions can be found quicker than the only one resulting from a classical method with a non‐singular coefficient matrix. Therefore, in the case of the analysis of multi‐branch and multi‐node non‐linear circuits using iterative methods, it is beneficial to introduce superfluous loops. This results in more economical computation and faster convergence.

The presented methods of solving multi‐branch and multi‐node non‐linear circuits using a singular formulation are universal and may be successfully applied both in circuit analysis and the FE analysis using edge elements for non‐linear problems with a large number of unknowns.

To present modelling and control technique of an electromagnetic actuator.

A 3D modelling technique of voltage‐forced electromechanical actuator takes into account: motion, magnetic non‐linearity and eddy current phenomena. Control problem of closed loop system is described by coupled electro‐magneto‐mechanical equations and non‐linear PID controller equations.

Presented methodology offers a powerful tool for analysis of control systems with distributed parameters models and may contribute to the improvement of the electromechanical performance of electrodynamic devices.

As original contribution a position feedback control using conventional PID controller is applied for iterative determining inverse dynamic problem, that is finding input voltage for a given position of an actuator.