Патент USA US2134880код для вставки
Nov. 1, 193-8. T. E. MCDOWELL ET AL SELF EXCITING ALTERNA‘TING CURRENT MACHINE 2,134,380 ' Filed Aug. 16, 1955 d . M Patented Nov. 1, 1938 2,134,880 UNITED STATES 7 PATENT OFFICE 2,134,880 ‘SELF-EXCITING ALTERNATING CURRENT MACHINE Thomas E. McDowell, Oak Park. and “MG. Howard, Chicago, Ill., assignors to The Pyle National Company, Oliicago, 111., a corporation of New Jersey Application August 16, 1935, Serial No. 36,454 3 Claims. (Cl. 171-223) The present invention relates in general to al oxide type of recti?er, it has been found that ternating current machines, such as generators, aper recti?er of the copper sulphide type, such as a and is more particularly concerned with the pro vision of improved means for excitation of the 5 ?eld coils of the machine. » The present invention is particularly ‘adapted for use in connection with train lighting systems, and is of special utility for the furnishing of power for the head light of the locomotive. On the other hand, it will be'appreciated by ‘those skilled in the art that it may, with equal facility, be utilized for other purposes where the genera tion of electricity is required, and moreover, al though the invention is disclosed as being em Ll bodied in a single phase generator, it is contem- . plated that the principlesv of the invention may likewise be ‘embodied in apparatus adapted for multi-phase operation. Generators for use in connection with train 20 lighting systems, particularly for furnishing power ‘to the locomotive headlight, are con structed to'operate at a relatively high frequency, for example, 400 cycles, and generate at normal operation a line voltage of around 32 volts. Gen erators so constructed are comparatively small and do not take up a great deal of space. 30 This feature is of particular importance in train light ing systems. Moreover, for many reasons, it has been found desirable to use alternating‘current in this connection rather than direct current which necessitated the replacement of brushes, cupric sulphide recti?er or one having similar characteristics, has many desirable features. This type of recti?er is of smaller size, lower cost, ' is capable of operation through a wider range of ambient temperatures, and has the inherent ~‘ advantage of being self healing when the copper sulphide ?lm is punctured. In attempting to use the copper sulphide type of recti?er, it was found that the recti?er would operate at good e?iciency at comparatively low frequencies such as 60 cycles, but that when it was operated at the normal operating frequency of the generators, such as used in connection 15 with train lighting systems, namely 400 cycles, the e?lciency of the recti?er would be decreased when , an inductive load such as the ?eld of the gener ator was applied to the recti?er output circuit. The present invention therefore resides in the 20 .general application of this compact lower cost recti?er to alternating current generators and especially to the type utilized in connection with railway lighting equipment, whereby self excita tion and desirable operating advantages are se 25' cured. , In accordance with the principal features of the invention, it is proposed to provide an alternat ing currentgenerator of any one of the three well known .types, namely, the inductor type, the 30' type having a rotating armature, or the rotating etc., whereas in the case of alternating current,_ ?eld type. In whichever type is used, the direct it is possible to use the inductor type generators, current ?eld coils may comprise a main ?eld and thus doing away with any brushes whatever. It an auxiliary ?eld for compound operation, and has heretofore been proposed, in order to make recti?ers of the copper sulphide type or other 35 the alternating current generator as simple as type having similar characteristics as are utilized possible and eliminate the use of auxiliary equip for individually exciting the main and auxiliary ment such as direct current exciters for the ?eld ?elds from the alternating current delivery cir winding, to utilize a recti?er suchas the copper cult of the generator. One of these ?elds, as for 40 oxide type to excite the direct current ?eld wind example, the main ?eld, may be excited from ings of the generators, which in the case of the such a recti?er connected directly across the de 40’ inductor type is. arranged to build up from re livery circuit. It is preferred to excite the auxil sidual. . Although the copper oxide recti?er has been ) found to be very well suited for this purpose on account of its instantaneous operation assoon as the generator is started, it, however, possesses the inherent disadvantage of being relatively large and requiring a substantial amount of space 50 for its mounting. Moreover, the satisfactory op eration of this recti?er is limited to a relatively narrow temperature range, and there have been - installations where the recti?ershas ceased to function at low temperatures. In seeking to 65 overcome the inherent disadvantages of the cop-. iary ?eld from a similar recti?er which has its input circuit connected to the secondary of a. transformer having its primary connected in se 45 ries in the delivery circuit of the generator, so that the auxiliary ?eld will be excited in accord ance with the .?ow of current or load on the de livery circuit of ‘the generator. In order that the load on each recti?er may 60 be of substantially unity power factor, it is pro posed to insert condensers across the respective ?eld windings. Moreover, the operation of the recti?ers is also improved if condensers are in serted across the input circuit of the rsctiflers. 55 2 2,184,880 An additional feature resides in the provision of means for automatically applying full line voltage to the recti?er which is utilized for ex citing the main ?eld winding, when the generator is being started up and is operating on residual, and thereafter, function in such a manner as to apply less than full line voltage to the recti?er as the generator comes up to normal speed and full voltage at normal frequency. This is dis 10 closed as being accomplished by the use of a choke coil which is inserted in the supply circuit to the recti?er. This choke coil, as is well known in the art, will have an increasing potential drop across its terminals as the frequency of the volt 16 age applied thereto and the recti?ed current is increased. Other objects and features of the invention will more fully appear from the following de through conductors 25 and 28 to the auxiliary ?eld windings I2-l2. - Asv in the case of recti?er II, the recti?er 24 is likewise improved in e?lciency by inserting a condenser 21 across the input circuit of the recti ?er, and a condenser 28 across thev output circuit of the recti?er. ~ In the drawing and description, recti?ers have been disclosed and described as being of the full wave type. It is contemplated, however, that the invention is not to be limited to the use of full wave recti?cation, but that half-wave recti?ca accompanying drawing, which illustrates a pre tion might be used with equal facility, if desired. From the foregoing description, it will be ap parent that the present invention provides im 15 proved means for exciting the ?elds of alter nating current machines, which makes use of low cost, small size rectifying elements of the copper sulphide type; which is so arranged that the recti?ers operate at substantially unity power 20 ferred embodiment thereof and in which: factor with the result that high efficiency is at tailed description, taken in connection with the The drawing diagrammatically illustrates an tained; and wherein the impressed voltage of embodiment of the invention in connection with the main field recti?er is automatically controlled so that line voltage is applied at the time of start a compound alternating current generator of the self exciting type. ‘As shown on the drawing: In the disclosed embodiment of the invention, the generator armature winding is shown as be ing connected to an alternating current delivery circuit II! which may be connected to any de sired load, such as a headlight of a locomo tive etc. In the present disclosure, the generator is pro vided with main direct current ?eld coils ll--II and auxiliary compound windings embodying ?eld coils l2-l2. Although a compound gen erator has been chosen to illustrate the present invention, it will be readily apparent that the invention may be utilized for generators operat ing with shunt characteristics. The main'?eld winding H is excited from a bridge recti?er of the cold type having copper sulphide elements, the output circuit of this rec ti?er being connected to the ?eld windings by 45 means of conductors I4 and I5. One side of the input circuit of this recti?er is connected by con ductor 15 to one side of the delivery circuit, and the other side of the input circuit of this recti ?er is connected through a choke coil IT to the other side of the delivery circuit. While a choke coil has been disclosed in this instance; it has been found that a resistance may be utilizedin stead, and that a resistance under these circum stances gives quite acceptable operation. The operation of this recti?er is also found to be improved by inserting a capacitance such as a condenser it across the delivery circuit at the terminals of the generator windings and a con— ing the generator and less than normal operating 25 voltage is applied when the generator has come up to normal operation with normal speed, volt age and frequency. _ Now, it is of course to be understood that al though we have described in detail a single em bodiment of ‘our invention, the invention is not to be thus limited, but only insofar as de?ned by the scope and spirit of the appended claims. We claim as our invention: 1. In combination, an alternator having an armature and a ?eld winding, and recti?er means to supply said ?eld winding with an exciting cur rent, said recti?er means comprising a plurality of rectifying elements arranged in a bridge‘ type circuit formation with one pair of apices con 40 nected to said armature in series with a reactor I and with the other pair of apices connected to said ?eld winding, a ?rst capacitor means con; nected bridging said one pair of apices and a second capacitor means connected bridging said other pair of apices, said reactor being arranged _ to selectively affect control of current through said recti?er as the voltage of the alternator varies with speed and ?eld current. 2. In combination, an alternator having an ar mature and a ?eld winding, and recti?er means to supply said ?eld winding with exciting cur rent, said recti?er means comprising a plurality of rectifying elements arranged in a bridge type circuit formation with one pair of apices con 65 nected to said armature and with the other pair of apices connected to said ?eld winding, a ?rst capacitor means connected bridging said one pair denser is across the input terminals of the bridge of apices and a second capacitor means con recti?er, as well as a condenser 20 across the ?eld nected bridging said other pair of apices, and means interposed in series with said one pair windings. These condensers counteract the in ductive reactances of the respective windings and of apices to automatically control current there through' as the voltage of the alternator varies result in operation of the recti?er at substan under the combined in?uences of speed and ?eld , tially unity power factor and consequently great er e?lciency. Moreover,__ these condensers also excitation. 3. In combination, an alternator having an ar tend to smooth out the ‘ripple in the recti?ed mature and a ?rst ?eld winding and a second exciting current.v For the auxiliary winding 12 which is utilized ?eld winding, means to supply said ?rst ?eld for compounding the ?eld excitation in response winding with exciting current, said means com prising recti?er elements arranged in a bridge 70 70 to load changes on the delivery circuit, a trans former 2| is connected with its primary in series ~ type circuit formation with one pair of apices connected to said armature and with the other in the delivery circuit and its secondary con nected through conductors 22 and 23 to the pair of apices connected to said ?rst ?eld wind supply terminals of the bridge recti?er 24. The ing, a ?rst capacitor means connected bridging output terminals of this recti?er are connected said one pair of apices and a second capacitor 1‘ 3 means connected bridging said other pair 0! apices, means interposed in series between said armature and said one pair of apices to selec tively a?ect current flow through said recti?er as the voltage of the alternator varies under the combined in?uences of speed and ?eld excitation, means to supply said second ?eld winding with exciting current, said means comprising a series transformer having its primary in series with a 10 load output wire and having its secondary con nected to a ?rst pair of apices of a bridge cirg cult formation of a plurality of recti?er ele ments, the second pair of apices of said bridge circuit being connected to said second ?eld wind ing, a third capacitor means connected bridging 5 said ?rst pair of apices and a fourth capacitor means connected bridging said second pair 0! apices. THOMAS E. MCDOWELL. JOHN G. HOWARD. 10"