Title :
Multiconductor transmission line analysis of steep-front surges in machine windings
Author :
Lupo´, G. ; Petrarca, C. ; Vitelli, M. ; Tucci, V.
Author_Institution :
Dept. of Electr. Eng., Naples Univ., Italy
fDate :
6/1/2002 12:00:00 AM
Abstract :
The numerical evaluation of the electrical stress in the line-end coil of the stator winding of a medium voltage motor fed by a pulsed width modulated (PWM) inverter seems to be indispensable for a rational design of the machine. In order to fulfil such a task, the system, composed of a feeder cable and a stator winding, is modelled and simulated by using multi-conductor transmission line theory. The model can take into account the main phenomena occurring along the lines, i.e. the propagation and the reflection, together with the time dispersion introduced by the losses, eventually dependent on the frequency. The multi-conductor transmission line is solved in the time domain by adopting a technique based on the perturbation theory of the spectrum of symmetric matrices, which sensibly decreases the computational effort with respect to the analysis in the frequency domain. Furthermore, an accurate calculation of the characteristic matrices, which contain the cross-sectional information of the line, is performed by means of a FEM package, so taking into account the effective field distribution in the region of interest. The influence of the accurate evaluation of the capacitance and inductance matrices is considered by comparing the numerical results of the proposed model with those obtained by a simple equivalent circuit, frequently adopted in the literature. In order to validate the proposed model, the simulated results are compared with experimental data
Keywords :
electric machine analysis computing; equivalent circuits; finite element analysis; induction motors; multiconductor transmission lines; stators; surges; time-domain analysis; transmission line matrix methods; FEM package; capacitance matrices; electrical stress; equivalent circuit; feeder cable; inductance matrices; line-end coil; machine windings; medium voltage motor; multiconductor transmission line analysis; perturbation theory; pulsed width modulated inverter; spectrum of symmetric matrices; stator winding; steep-front surges; time domain; traction motor; Coils; Medium voltage; Multiconductor transmission lines; Pulse width modulation inverters; Stator windings; Stress; Surges; Symmetric matrices; Transmission line matrix methods; Transmission line theory;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
DOI :
10.1109/TDEI.2002.1007711