DC/DC çevirici yardımıyla doğru akım motor hız kontrolü

Abstract

ÖZET Bu çalışmada dc/dc çevirici kullanarak doğru akım motor hız kontrolü yapılmıştır. Doğru gerilim şebekeden alınıp dc/dc çeviriciye uygulanmıştır. Bu projede dc/dc çevirme işleminde darbe genişlik modülasyonu ilkesi temel alınmıştır. Kıyıcı, çıkışındaki güç mosfed transistorleri yardımı ile 400 V`da max 13 A' lık akımı motora sağlaya bilir. Dc/dc çevirici, anahtarlamalı olarak: çal ıştırılmaktadır. Bu projede motor 'un iki bölgede çalışması ger çekleştirilmiştir. Motor miline bağlı bir takogeneratör yardımı ile sistemin his geribeslemesi gerçekleştirilmiş tir. v -

SUMMARY DC MOTOR SPEED CONTROL BY USING DC/DC CONVERTER Dc/dc converters, commonly called choppers because o-f their principle of operation, 5rs employed to vary the average value o-f the direct voltage applied to a lead circuit by introducing one or more thyristar between the load circuit and a dc source. The -function of a chopper is illustrated by Fig 1.1a. (b) Fiej 1,1 t-unctian of a ZC Chop pes The manner in which the average load voltage is reduce below that of the source is illustrated in Fig 1.1b. This shows that the chopper applies a train o-f unidirectional voltage pulses to the load circuit, tne agnitude of these pulses being the same as tha~ a- m ne vı -source voltage» Load voltage V may be varied in one of these different ways» i» t0N may be varied, while periodic time T is held constand - pulse witdh modulation» 2. tcU may be kept constant while T is varied - -fre quency modulatoin. 3. Combine pulse-witdh and frequency modulation. In practice, all choppers do not maintain the ide al output voltage variaton show in Fig l.ib, but it is convenient to ignore this possibility while discussing the basic principle of operation of the various types of chopper that may be built. In part 2, therfore, the con verters to be anal i zed and first briefly explained in terms of a highly simplified and idealized model» and they ars then anal i zed in the detail required by the cir cuit designer. Choppers are employed in variable speed dc drives, where it is desirable to eliminate the waste of energy :- the form of heat produce in starting or control register. or where the operating characterictics obtained by sucn methods of control would be unsatisfactory. Thus a chopper may be employed the supply the armature of a se- perately-excited dc motor, or to supply a series -wound dc motor. It follows that choppers a.rs employed in dc transportation drives all of kinds where the ability c- = chopper to impose a current limit on the load circuit is of part i c u I -B.r^ va 1 ue » Figure 1 » 2a illustrates the basic principles of a type A chopper, in which both V0 and Ie can only be posi tive. Dl is a free-wheeling diode» Two.possible condi tions of operation b.y^q illustrated in Figs. 1.2b and c, where it is assumed fehad the control is ov means of fre quency modulation. In Fig. 1.2b the load current ia is discontinuous, so chab during the interval for which i is zero, v0 =Ve w In Fig» 1.2c, the periodic time ~ has been reduce to sucn an extent that i h«-= not ceased to flow Ql is again iurn on» As a sequence, tne output voltage vQ consist of a -rain of rectangu- ar pulses o- magnitude V-, An L -crease of load cir^c/~:. ~: inductance L or a reduction of Vc would also tend to -esult i~ a ccr- t i n u. o u s o u t p u t c u r r e n t. Figure 1.3 illustrates a type 9 cnc-ssr, in wnich ls may be either positive or negative, but v0 can only be positive» A converter of this type may be employed wit` a load circuit that is capable of regenerating ana retur ning energy to source V. Here there are two thyristor that can be turned on and commutated. For operation with positive output current, thyristor Ql and diode Dl arm controlled and function in exactly the same was as do t `a - Vll -^c «on ^ >o -s-nnnp- `HK! f«> <W M. 2 Bas.ncipie üt ; tjp ;- - r n. thyrıstor and d iade af Fig, L2a. nor -pş`a