USRE15094E - By general - Google Patents

Description

G. H. HILL, DEC'D. GENERAL ELECTRIC co'mPANY, ASSIGNEE.

REGENERATIVE BRAKING APPLICATION FILED DEC.15| 1919.

Reissued Apr. 26, 1921 9 x. nrm M05 3; em n wvD r m m w L Em A n mwvm 8 50 n58 f w .UNITED STATES PATENT OFFICE.

GEORGE H. HILL, DECEASED, LATE F SCHENECTAJDY, NEW YORK, BY GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK, ASSIGNEE.

REGENERA'IIVE BRAKING.

Specification of Reissued Letters Patent. Reissued Apr. 26, 1921 Original No. 1,281,959, dated October 15, 1918, Serial No. 120,667, filed September 18, 1916. Ap'plication for reissue filed December 15, 1919.

I To all lwm it may concern.

Be it known that GEORGE H. HILL, "deceased, late of Schenectady,.in the county of-Schenectady, State of New York, during his lifetime invented certain new and useful Improvements in Regenerative Braking, and that the GENERAL ELECTRIC COMPANY, a corporation Organized and existing under the laws of the State of'New York, assignee of GEORGE H. HILL, now deceased, hereby declares to the best of its knowledge and belief that the following specification, taken in connection withthe accompanying drawing,

forming a part of the same, is aclear, true,

- by causing it to act as a generator to return energy to the line. While the invention is of general application in the field of motor control, it is particularly applicable to electric traction systems. In the operation of trains on heavygrades, one of the great problems is the braking of the train. In some instances with the uusual air brakes on long grades, brake shoes will be over heated or destroyed in a single'trip. The wear on the rails is also a matter of serious consideration. Furthermore, trouble is oftentimes caused by overheating the wheels. It has heretofore been proposed. to brake electrically operated trains at least in part by causing the motors to act as generators and return energy to the line, aoform of braking commonly known as regenerative braking. Certain difliculties, however, have been encountered in the use of such systems by reason of the almost universal I use in traction work of series motors which are not satisfactory" for regenerative braking, if operated as straight series generators, because of their unstable characteristics under conditions of variable speed or variable line Serial No. 345,031.

age. Because of this fluctuating line voltageit has been difficult to keep the regenerative current within safe limits during the braking operation and, at the same time, to permit a desirable speed for the locomotive or train and to have the braking effort entirely under the control'of the operator. One of the objects of the invention is to provide Various arrangements have been an improved control which automatically takes care of the fluctuating line voltage whereby the operatormay obtain thedesired train speed during the regenerative braking period and the desired degree of braking at all. times without danger to the motors or other apparatus due to excessive current.

In carrying the invention into effect, the control of the regenerative braking effect :is secured by furnishing'excitation which may be variable for a portion of the motors and then using this portion to vary the excitation of the other motors by connecting it in. a closed loop with the fields of the other motors, the motors all being operatively connected to the supply circuit. In one form of the invention, variable excitation is furnished for this portion of the motors and this excitation may be obtained in any suitable manner, but it is-preferable to obtain 1 it by means of a small generator which is vdriven by a motor energized from the source of supply for the locomotive or train. The regenerative braking efi'ect is accurately controlled by varying the excitation of. this small generator in' any suitable manner or by varying a resistance in the closed loop in which the armature of the separately excited portion of the motors and the fields of the other motors are included or by varying both the excitation of this small generator mot or generator set. Atthe. same time the armature of this motoris connected in'a closed loop withthe fields 1 2', and Sftof' the-other motors. By means of a variable resistance 12, included inthisfclosed loop, tl ie niotor- -n1ay he operated at voltages approximatingitsnormal rated voltage and hence be caused to develop a braking effect 1 approximating that developed by the other motors. ;-,,The' resistance 12, which is; '75 cui t connections for the'motors on thefirst traversed] by the regenerated current I I point motoring; Fig.3 shows a diagram of traversing the motors 1 2, audit, also fund,

. v, circuit connections for thezniotoirs on the tions tolimit thefluctuations in the regenerc last pointmotoring;Fig 4; showsa diagram ated, current, upon Lsudden" variations: in Q of circuit connections lorwthe motorson the thesupply circuitfvolftage both byyarying first'point'otregeneiative. hraking;]F-igsy5 the portionflofthe voltage developed by the andlfi show' diagrams ofcircuit connections motors 1', 2; and'S consumed therein andcby for modified systenis of regeneratiw brakvarying the portion of thevoltage of the:

v and the resistance ,inxthe closed loop; Inv certain forms of the invention, the "portion fof the motors Which'supplies the excitation forjthefields of the others carries only the excitation current and is notlrequired to also carry theregenerated current delivered to the. supply'circuit. I. c Referring to the drawings, Figure'l shows a! system of motor control embodying the v invention ;wFig. 2 shows a diagram of C11? ingilemloodyingthe invention. I e v motor 4; consumed therein, thereby varying j eferrl ng" to Fig. 15 the contr'ollerC havthe current 11]; the field w1nd1ngs*l",2, and

3f land hence the voltage developed by the ing a plurality of circuit imaking contacts v I isadapted to'connect the motors and conme ers 1, '2} and 8. 1, By y ng the-resisttrol apparatus infthe "various relations as ancsie, the ibrakingefl'ect of the moto shown inFigsQQ, 3 mm, The motors hav- 2, and andalso of the motor twmay be ing'theiarmatures1;2, 3', Land series fields varied. i A variable resistance '13 in 'the 1", 2', 3; and 4f respectively are adaptedlto shunt field of thegenerator;-6 is provided be included in se in all the steps of the for varying the voltage of this/generator f I e'resistance 5 is'adapt- 'dthusthe excitation of the-field winding ed to lie-included 1 themotor cirfcuits duty- Although means com irising the con- 7 ring starting land to be controlled by meansfer C are shown in Fig. 1 for varying 1 of thecontrollerCL' The series field] 4 of W the resistances Band-13 siniultaneously'and the rn otor having the armature 4 is supplied in the samesense, the invention is in no Way 1 with a. separate excitation during" the relimited to-varying'these re stances inithis' g ativ braki stepsinfthe, surgeonparticular manner. vThe cii-cuitconnections .trol; m ns f' tors a otor corresponding to the position'd ofthecone generator; set' havingaf motor Tj'energized tr'oller, C" are shown in Fig. a; It will be from the 'jsourceofsupplyj; A s'ma'll genernoticed that: thefconnections between the at'o'r 8 dr' en'bythe motor? of'th motor motors-and the sourcev of supply have been enemwn ff f pted" supply the exnaintainedandthatgone ofthemotors, the citation for-'thel'field'Q the H6 in or liavingthearmature 4g and series field 7 auditsownI shunn'fidd I et, is given a separate excitation byineans fThe'operaition f th' rangem is as of the generator 6 and the armature of this ""f 11=- 'F i p 1 motor isvconnectcd in a closed loop Withthe p I 3 When it is'desired'to start the locomotive 3eTieS fieldswf 1 Ollie together i p t in' th tr ll ti wm d 't the, with axresistance 12.- In order tofin'crease, firstfip'oint a thus"- connect1ng allythe-"inotors the reg ivfl r king cfiiect th in s'eries witl1'al11oftheqstarting resistance 11 1 is movedmto-the position i5 includedfin the;circuit, the e'onnection or "the motors "being asshown inFigLQ; The circuit at this aoint is from the-trolley pole @11 which is connected to {the source of sup- .ply,' through -the'z'controlling resistance 5,

mflt r 5 7 9 a I H l i series'fi'elds1;"2,.v3 ,,v p j r 1 d9 of theygene turningthe contiol 1 ator'fii -short" circuitedythus increasing v section @of y the accelerating resistance 'thexvoltageof this generatorandincrc sing" shortcircuit'ed t creasing thes j thelexcitationof series'fi e1t"and"" his.

and rning: theg'co way raisingthevvoltage he armat re j i and increasingthe excitationof-the seri v v v fields 1",- 2T5ya'nd Increasin Ptheexcitavrectlyvin seriesac ss'the'li'ne.v tionoft'he fields ,QQand'S auSes highen 1 1 desired tohrakeithe locomotiveortrain voltage to zbe develo edifin the armatures 1, controller"ismove to the positiondpwhenj 2, andB ovidingthepspeedv thereofhdoes iv'enia separatewexcita 'notfdecrf se,iand=,iif the sameoria greater e generator 6 of-ithe' I d flow therein, {greatershown in Figs. 1 and 4 with the exception that the resistance 12 in the closed loop including the armature 4 and the fields 1', 2,

3 has been omitted. The regulation of the regenerative effect in this system is obtained entirely by varying the excitation of the small generator 6, and the resistance of the .closed loop is not varied. An arrangement 2', and 35',

such as shown in this figure is entirely satisfactory for some situations where the regenerative braking must be controlled, but does not afford such an accurate or safe regu lation as that shown in the other figures. In the modifications illustrated in Figs. 1 to 5 inclusive, the armature 4 is not traversed by the curnent traversing the armatures 1, 2, and 3 and hence the'lattermay be operated at full current capacity without an overload being imposed upon the armature 4.

Another modified form of the invention is shown in Fig. 6 in which the series connection' is maintained between the armatures 1, 2, 3 and their respective series fields 1, 2' andv 3 but the armature 4 is disconnected, from this series connection and its series field 4 is also disconnected from the other motors. The series field 4' is separately excited'by means ,of the generator 6 of the motor generatorset running from the line,

and the shunt field 9 of-this generator is controlled in the same manner as the system shown in Figs. 4. and 5.. The control of the excitation of the series fields 1, 2, and 3' may 'be effected by varying either the resistance 12, or the resistance 13, or both the resistance 12. and the resistance 13.

rincipal difierencebetween the system of ig. 6 and that of Figs. 1 to 4 is that, in the system of: Fig. 6, the armature 4 is located so that it is traversed both by the current traversing the armatures 1, 2, and3 and b the current-traversing the fields 1', 2-, and 3', while in the system of Figs. 1 to 4, the armature 4 is located sozthat it is traversed only by the current'trave'rsing the fields 1',

.The arrangement gives, for some conditions, 2. more desirablespeed control during braking than could be obtained'with ordinary'systems using four motorsqin series or an arrangement in which two motor-sin series are connected. in parallel. with two others in series; In arrangements using four motors in series which have heretofore been proposed it has been found to be impossible The r to get a higherspeed than a certain value, for instance 20 miles per hour, without weakening the motor fields to'such an extent as to render the motors unstable as generators. If the motors were connected two in series in parallel with two others in series it. has been difficult to secure a low speed during regenerative braking because of the fact that with such a connection fora speed of, for instance, less than 30 miles per hour, the field current would have to be larger than the windings could stand without overheating. By the arrangement a speed which is midway between the highest safe speed of the four motor series connection and the lowest obtainable speed with the s'eriesparallel arrangement may be secured. The arrangement therefore inherently obviates the practical' difficultis with those other arrange ments which have been heretofore proposed. It will be further noticed that in the arrangement the separately excited motor which is used to furnish the excitation for the fields of the other motors also furnishes its quota of braking effect to retard the speed of the locomotive or train, and with the resistance 12 included inthe closed loop, the

armature 4 may be working at somewhere to represent the bestv embodiment thereof; but it is desired to have it understood, that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

'What is claimed as new and desired to secure by Letters Patent of the United States, is

1, In a system of control, the combination witha supply circuit, of a plurality of dynamo electric machines operatively connected tosaid supply circult, one of said machines being also connected to excite another and having'alower average voltage than said other machine. r

2. In, a system of. control, the combina tion with a supply circuit, of a plurality of similar dynamo electric machines regeneratively connected to said supply circuit, one of said machines being also connected to excite another, and means for producing different voltage ranges upon the respective machines.

3. In a system of regenerative' control,

rape;

14. The method of regenerative braking in a system comprising a plurality of similar series wound dynamo electric machines adapted to either drive or .to brake a common load, which-consists in connecting a portion of the armatures of the machines to a supply circuit through a resistor with the remainder of the armatures of the machines connected in a local circuit to the resistor, operating as an exciter for the said portion of the machines, and then controlling the braking effect by varying the excitation of the exciter portion of the machines. i

15. The method of regenerative braking in a system comprising a plurality of similar series wound dynamo electric machines adapted to either drive or to brake a common load, which consists in connecting a portion of the armatures of the machines to a supply circuit through a resistor with the remainder of the armatures of the machines connected in a local circuit to the resistor, operating as an exciter for the said portionof the machines, and then controlling the braking effect by varyingthe resistor and varying the excitation of the exciter ortion of the machines. :16. he method of regenerative braking in a system comprising a plurality of series motors adapted to drive a common load,

' which consists in maintaining the connection between the series fields and armatures of a. portion of said motors and, the source of supply, varying the excitation of'another ortion of said motors, and connecting said ast named portion in a local circuit with the field windings of the first named portion to thereby control their excitation.

'17. The method of regenerative braking in a system comprising a plurality of series motors adapted to drive a common load, which consists in maintaining the connection between the series fields and armatures of a portion of said motors and a source of supply, Varying the excitation of another portion of said motors to cause this portion to act as 1 a generator, connecting said last named portion in a local circuit with the field windings of the first named portion of the motors, together with a resistance, and in then controlling the braking efi'ect by varying said resistance.

18. The method of regenerative braking in a system comprising a'plurality' of series motors adapted to drive a common load, which consists in maintaining the connection between the seriesfields and armatures of a portion of said motors and a source of supply, varying the excitation of another portion of said motors to cause this portion to act as a generator and connecting said last named portion in a local circuit w th the field windings of the first named portion of the motors, together with a resistance, and

to act as a generator, connecting said last named portion in a local circuit with the field windings of the first named portion of the motors, together with a resistance, and in then controlling the braking effect by varying said resistance and varying the excitation of the motors operating as generators. r

20. The methodof regenerative braking in a system comprising a plurality of series motors adapted to drive a common load,

which consists in maintaining the connection, between the armatures, of .said motors and the source of supply, separately exciting a portion of said motors, and connecting said portion in alocal circuit with the field windings of the other motors to thereby control their excitation. 1 H

21. The method of regenerative braking in a system comprising a plurality of series motors adapted to drive a common load, which consists in maintaining the connec tion between the armatures of said motors, and a source of supply, separately exciting the field windings ofa portion of said motors to cause said portion to act asa. generator, connecting said portion in a local circuit with the field windings of another portion of said motors, together with a resistance, and in then controllingthe braking effect by varying said resistance.

22. The method of regenerative braking in a system comprising a plurality of series motors adapted to drivea common load, which consists in maintaining the connection between the armatures of said motors.

and a source of supply, separately exciting the field winding of one of said motors, connecting said separately excited motor in Ia local circuit with the field winding ofanother of said motors, together with a resistance, and then controlling the braking effect by varying said resistance.

, 23. The methodof regenerative braking in a system comprising a plurality of series motors adapted to drive a common load, which consists in maintaining the connection between said motors and a source of supply, separately exciting the field windings of a portion of said motors to cause said portlon to act as a generator and connecting said portion in a local circuit with the field windings of the other motors, together with aresistance, and then controlling the braking oit ed' portion of the motors;

f regonel ativewbr' I, ng 2p pllii'alitygiof series load,

heirarmatures tot'he-source' 'of Supp1y',"and. v gvaryind the oxoitzption of said portion of for controlling the. regenerative x ng h field "WW1 motors andoonnootlng enerators and: then b v-arylng ty' of s'eri'es ptod 'tofdrivo a; common load, nr maintaining "the connecsource of serlos with 29; A jaratnsflfor regenerative braklng, gla plnl ahty of ,SEIIQS motors con common 1ozu,d,-meansf for sepw said motors, meansfor connecting the ajlgm' cures of allof said oi' snndl the rem e'ries' with onelr a other and, source, of supply, and: a stantial X I "1' fed an d 'd windings; and th .armatui" of that which is. separately excited,

" z oombination', a, plurality o common-load, means for: 00 motors to a sour oe of Suppl d or for' connofiing one of eparatoly excited generator uit vithqtho field windings saidumotors for I braking; "and" I mnintalmngnt" all .gimes 1 tho conneotion f said: motors" and he eylmothod of eg no atW g k I o Inon 10; F

1r lit; with theE field windmg'mi s together vith;the 'i esistc I a t' asv genera;

the; braking, I

\ g y 11061 and' varymg excited" motors "for ,-con' ice", of supply to 11s fox controlling the said moi zo' said inotors the 1 fio'ldwlndin the "oonneo 1' o 1 said motors in locaLol rcni 1r]. wlndmgs of the: other motors malntzun g he sourceof supply, and for soparatoy 'ng said fi'rs tvn medmoton' Y ppai'atus. regenerative braking, ing: a y 01 series; motor connected to" a [Common load, "means f separately exciting the 5 field winding of- "on of said motors, nieansl foroonneoting .th air 1d windings of alliu of js'a'd vith-g one another and to the' connection Of all the 'W1I1dl11gS m is'en'es, wlth then' armatures,

Images