الفهرس 
EXPERIMENTAL INVESTlGATIONSOnly 14 pages are availabe for public view
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Abstract
The research presented deals with a reliable and
effieient solid-.tato inv~rter system loaded by an indu-
vii
ction motor. Experimental investigation as well as theoretieal
analysis of the systGm have been carried out •
.A d.c. link conver-t er has been d~signed and exe-
cuted in the laboratory. The firing circuit has been
specially constructed, it delivers hard drive pulses
having a frequency which can be smoothly varied from
about 15 to 2)0 HZ. Th~ fr·~qUf’ncyvariation is achieved
by using an astable mult ivibrator. Frequency variation
can be simply done by means afapotenti.0meter. This astable
mu Lc i.v Lbrator is thermally stable and is not affected
by load transients. Thyristor protection against
high dV/dt as well as high di/dt and over-current have
been taken into consid6ration.
Oscillograms of t he d If’f’erx.n t variables in the
system UDd~r investigation have b~en rpcorded. Extensive
tests were perLormed for diffsr.0nt circuit conditions
under steady end transient states. Bff~ct of the variation
of circuit parameters upon the system behavf.oun is
also studied Mathe.natical ans Lys,s of the basic circuit as well
as of the modified cLrcu i t has been introduced. The
mathematical expressions obtained yields a simplified
digital computer model~ The analysis is concerned with
single phase as well as with three-phase inverter cir~
caits.
Digital computer simulation of the system has been
executed. Three programs are presented for the three
different cases which hai,;~bGCD tackled. These are, the
basic circuit with passiva loads, the singl~-phase inve~.
rter 10aded by a single phase Lnducti.on motor, and the
three-phase inverter-motor set.· The numerical solution
has been carried out on the leL 1900 series computer of
~o·Univ8rsity. The program caD execute six different
operations. These are, the st art Lng condi t Lon.,the
steady state performance, the spssd torque ch8r&cteris- ..
tics, the step variation in toXqu8, the step variation
in frequency, and the sudden opening in the load termi nals. In the solution of the syst;;:;m,.a g~od method has
been adopted ~mich avoids the divergence in the solution
of differential equations. How8vt-r, maximum saving for
the computer running and storage times have been consi-
dered.