USRE14510E - Automatic control of phase-converters - Google Patents

Description

E F. w. ALEXANDERSON. AUTOMATIC CONTROL OF PHASE CONVERTERS.

APPLICATION FILED APR. 2. l9l8.

Fi I.

I Inventor: -Ernst F.wffl;exander-son His aTbtorney.

E. F.'W. ALEXANDERSON. AUTOMATIC CONTROL OF PHASE CONVERTERS.

APPLICATION FILED APR. 2. l9l 8. Reissued Aug. 27, 1918.

2 SHEETSQSHEET 2.

- Inventor: Ernst F W. fiTlexanderscrn.

His flttow-he g.

v UNITED STATES PATENT OFFICE.

ERNST r. w. ALEXANDEBSON, or SCHENECTADI,/NEW YORK, As smiron TO enum mn ELEo'rnIcrooMrANY nu'roma'rrc coiv'raoL or" rnasn-convnarnns.

Original No. 1,233,952, dated July .17, 1917, Serial No.

filed April 2,1918.

To all whom it may concern:

Be it known that I, ERNST F. W. ALEX- ANDERSON, a citizen of the United States, residing at Schenectady,

tady, State of New York, have invented certain new 7 and usefullmprovements in. Automatic Control of Phase-Converters, which the following is a specification.

My invention relates to the automatic reg- 10 ulation of electro-dynamic phase converters in such a manner as to cause them to deliver balanced voltages under-load.

' It is well understood that a machine of the polyphase induction motor type having a squirrelcage or phase wound rotor, if it has one. phase a of the primary connected to a single phase source, will, once it is started, run as a single phase motor, and at no load its s ed will be practically synchronous spee If a polyphase, load the primary windings of the motor, polyphase currents may be taken ofi. Two systems of electrically connecting such a con verter between the single phase source and polyphase load circuit are illustrated in my previous Patents, #901,513 and #1,150,652.

In the former patent is illustrated a parallel arrangement, of converter and load circuit in which one converter phase and one phase of the load, circuit are each directly connected to the single phase source, and the other converter phases are connected res ectively in series with the -'other load p ases. Although, as disclosed in this pat cut, it is possible to select such a relation and ratio of converter windings and of thevoltages impressed anced voltages may be secured at the motor terminals and hence balanced polyphasecur- 40 rents may be securedin the several phases at a predetermined load, nevertheless the load'departs-from said value an unbalanc ing of the voltages applied to the motor terminals and of thepolyphase currents will result. K i

The Patent #901,513 and my application Serial No: 815,280 filed January 29, 1914,

respectively disclose,- in connection with the parallel" arrangement of connections, the

verter; windings an of the voltages impressed thereon, in order that at predetermined loads a balance of the voltages ap- Speciflcation of Reissued Letters IPatent. Reisgi ed Aug, 832,985, filed a rii county of Schenec .converter phase and 15 connected to upon said windingslthat-balcuit and a threeidea of adjusting the connections of the con- 1 n coRroaA'rIoN OF NEW YORK.

27,1918. I is, 1914. Application for reissue Serial No. 226,307. I

plied to the motorv terminals and of the polyphase motor currents may be secured.

In the latter patent is illustrated a series. arrangement of connections in which one one phase of the load" circuit are connected, in series with each. other, to the single phase source andthe other converter phases are connected res ectively in series with the other load ases. r The Patent #1,150,652 and .my application Serial No. 815,280, filed January 29, 1914, each discloses, in connection with the series arrangement 0 connections, means whereby a balance of the volta es applied to the motor terminals and of t e'polyphase currents, is automatically and substantially maintained with varying'loads.

My present invention has for'its object the provision of means in systems-of; hase, conversion of the character.above re erred to whereby the; esired balance between the voltages applied to the loadphases and be-f tween the polyphase load currents is auto maticallyand substantiallymaintained for all leads, and to this end-1 have devised a novel system of control in. which suitable circuit changing devices are arranged to be operated automatically in response to an? electrical condition of the system. Inthe preferred embodiment oifmy invention the circuit changing devices are under the control. of current responsive devices in a plurality of phases of the polyphase system.

M invention will be more readilyunder-- stoo, by reference to the accompanying drawings, in which m invention is illustrated as applied to t e parallel arrangement of connections, and in which: 2

,Figure 1 shows diagrammatically my. in-; vention a plied to a two-phase machine of the polyp ase motor. type acting as phase changer between a single phase supply-cirphase motor. v siimlar view of the uivalent arrangement where he potential 0 thesingle+phase supply 'ci cuit is such as, to require the' addition of atransformer gas a part 0L the hase changer.

Fig.- 2 is a igs. 3, 4 and 5 are diagrammatic views I V is controllers.

,tion or'the' other. As will be' seen, the solej p shown a slightly different method of 0011- 125 trol, whereby In the arrangement shown in Fig. 1],; power is \supplied directly .from the mains 6 to a quarter-phase phase converter C ofthe 01yphase motor type and thence to the t reephase motor M In each case I have illustrated diagrammatically only the primary windings of these machines, which are,the' parts essential to an understanding of" my invention, but it will be each machine is provided with the usual sec- 'ondary winding; and that thismay' be disposed upon either the rotating or stationary. part, as may be'desired. Following the customary convention, the phase windings of displaced b ninety degrees, while those of the three-ph ase motor are displaced by 120 degrees. pon the motor phase 7 ofthe converter I provide suitable taps which are connected to the'-' fixed contacts 8 and 9 of One terminal of the line and one, terminal of the generator phase 11 are also connected to similar fixed contacts 10. These controllers may be of any suitable-construction, and I have shown diagrammati at 12 and 13 movable contacts asthe.

' cally Upon rotation development of a cylinder. these movable contacts will coiiperate with the fixed contacts 8, 9'and tovary the connectionsof the primary windings 7 and- 11 of the hase converter to change the phase relations ofthe voltages supplied and to vary the volts per turn applled to the. motor phase. These changes will operate in the manner-previously escribed'to 've balanced voltages at any load. With alanced voltages applied to a motor such as that W ose primary winding I'have shown at M, the currents and hence the heating in each phase, will be equal. For the operation of the controller, as by rotation of. a cylin: 'der carryingthe .movingcontacts 12 13,1" have -provided a motor 15 supplied with cur,- rent from mains 14. This motor has fieldwindings 16' arranged to cause rotation of the motor in op oslte directions. The field terminalsare 1e to. a switch 17 designed to connect one or theother to one of the mains I 14 according to the.,direction. in which it is desired torotate the motor." This switch is provided with current-responsive devices here shown as'solenoids18, 19, inoperative relation to two phases ofthe motor rirnary j M, so that when an .unbalancin of t e voltages delivered by the. converte produces an unbalancing of the currents in the: motor the o posing pulls on the arms-of the wi 1 be unequal, and move it in one direcnoid 18 is in serieswith that phase of the motorconnected. to the generator phase 11 of the converter while the solenoid 19 in series with one of the phases which is con nected directly to the source of This'location with respect to the motor obtained.

.understood that the load seems most desirable for the quarter-phase phase converterare shown mains 6 are connect verter, these ta fixed contacts 0 supp ied, while 12 will chan e'the volts [-thereto; '1 "grammatically in" Figs. 3, 4 and 5 r the sake of illustration switch supply.

, a" phases is, however, not essential, and is only one way in which the desired result may be With a mo tor load of the type illustrated the unbalanci g with increasing load will usually be in ,/one direction, and the solenoid operated switch with two coils will correctly control the circuit changing devices in the desired manner. Although this series relation of solenoids 18 and 19 to sensitive regulation, since a small change in "voltage mayproduce a considerable changein current, my lnvention is not limited thereto, but

includes any equivalent arrangement of current-r ponsive devices designed to regulate so for baa anced voltages- Where the voltage of the single-phase supply-circuit is such as to require the addition of a transformer, then the arrangement shown in Fig. .2 ma be used'. Here the Ito the primary of the transformer 20, to thesecondary of which are connected the motor M and the I converter C. When a transformer is used as part of the phase converter, it is found more convenient to arrange the taps, as at 21,22,-

upon the secondary of the transformer in stead of upon the motor phase of the cons being connected to the the controllers 12, 13. As '95 before, the motor receives a fixed voltage by being connected. to a top '23 upon the transformer. Due .to'the relative positions of the taps 22 and 23, itwill be seen that I 'movements of the controller 13 will vary 10 the. connections of thephase converter to chan e the phase relations ofthe' voltages movements of the controller e1 turn applied to; V

the motor p rise 7 of t e converter, ,.The"1 '5 control apparatus used is identical with that 1, and exactly similar results are ob taine T f S o fanthe. arrangements have been suchas tomalntain a constant voltage on the 1 motor, but'it maybe desirable toincrease the voltage with increasing load in order to increase the magnetizing current supplied have accordingly fshown jdia-- someof the possible arrangements of combined phase converter. and transformer, and, for

of the'posslbilities of my scheme, so designed these that the motor voltage is increasedwith increasing load 1120 while balanced voltages are. also obtained.

"The elements of the apparatus as dia" grammaticall shown in Fig. 3 are the same as those us Fig. 2, but If have here the impressed voltage on both the motor and the phase changer is increased simultaneously with the increasing load by moving the terminal 31 to theleft along the secondary of the transformer 30.

One terthe voltage supplied b verter and obtam" the the same time, by moving the terminal 32 ing that the position of the tion of a two-phase will be obvious that this is not leading from the motor phase"? of the phase converter, I further increase the volts per turn impressed on this winding, and thereby increase the flux supplied to the enerator phase as previously explained. t will be obvious from an inspection of the drawconnections 31 and 32 illustrated is such as anced conditions at no load, and that with an increasing load and consequent unbalancing my automatic device would vary-these connections to give the desired distortion in Order to obtain balanced currents in a poly phase load, and also increase the motor voltage. g

In Fig. 4 I have illustrated the combinaphaseconverter with a two speed quarter phase motor provided with a. neutralpoint. It may be'desirable in such an arrangementto use a quarterphase motor provided with two windings having different pole numbers, as, for example, X-poles' and Y-poles, and I have, but t therefore, illustrated such a motor,

essential to the utilization of my invention. a In this scheme, for convenience of control, I have a divided the secondary of the transformer 40 into two sections 41 and 42, and have also divided one phase winding of the phase converter into two sections 43 and'44 in order of one phase 49 of the motor An inspection of the drawing will show that here, too, as in Fig. 3, the illustration is ofthat position necessary for obtaining balanced that I may connect them on opposite sides voltages at no load, the motor phase of and needs no further connected to the motor.

the phase converter being connected in parallel with one phase 48 of the windings 43 .and 44 of the generator phase are connected in series with the: other phase 49. By means of moving the terminal 46, connecting the two sections of the secondary, I am able to simultaneously increase the voltage applied to the motor, and intro: duce an interpolated voltage in the series connected windings 43, 49 and 44. The effect of this interpolated voltage has been clearly described in m Patent #1,150,652, escription' here. -'By of the terminal hase 45 of the con- I am able to increase the volts tper ux movement to the right verter, turn applied and with increasing load.

obtain. an increased In Fig. 5 I have illustrated thecombina- "phase phase converter C the voltage apphase relation of,

to obtain balseen that my in various the motor, while motor M and a three- With this arrangement, movement'to the left of the terminal 51, which is provided as a common terminal of motor and phase changer, re-

tion of a three-phase sults in increasing the voltage applied to both machines to obtain increased magnetizing current in the motor M and increased volts, per

tor phases 53 of;the converter. Movements of the terminal 52,1eading from the motor phases of the phase-converter along the seeturn with increasedfiux in the moondary of the transformer 50, result in increasing the'distortion, necessary to produce balanced currentsin the poly hase motor; because of the fixed position 0 of the motor I have accordingly illustrated a few of. the many combinations of a phase converter of the type described and a poly.

as comprising an induction motor. I Obviously, my form of load, but can equall plied to any load wherein it--1s obtain'balanced voltages with varying values of the load. Further, aswas' set forth in the early part 'of the specification, itwill be device is entirely automatic, and that any unbalancing of the currents hases of the load due to unbalancing o the voltages will serve to set in operation my automatic control andfprothe dewell be' apduce the changes necessary to give sired result.

terminal 54 phase load, and, for the sake of convenience, have in each case shown the-polyphaseload invention is not'limited to such a desirable to The part'cular arrangement of a sole-- 1 noid operated switch controlling a motor driven controller is here described merely for the purposes of illustration, and I con ceive that various modifications of this particular arrangement and of the particular combinations of phase converter and pol phase load may be made, do not desire to be limited to the exact arrangement shown, but seekto cover in the appended claims all such modificationsand arrangements as fall within the scope and spirit of my invention.

.' What I claim as new and desire to se-' cure by Letters Patent of the 1s United States,

means, including a plurality of current responsive devices, forautomatically maintaining the polyphase currents substantially balanced under all conditions of load.

' 2. The combination with a single phase source and a polyphase load circuit, of a phase converter of the polyphase motor type electrically connected t erebetween, and

-means, including a plurality of current re- 1. The combination with a single phase ion and I accordmg y a tive voltages delivered to the deliver energy 7 means, including a plurality of current re-s' devices operativelly 0 ",volts per turn of supply, a balanced sponsive devices in operative relation to the branches of the maticall maintamin the polyphase currents su stantially ba anced under 'all con, ditions of load.

3. In combination a single phase source of supply, a balanced-polyphase load; means, includinga phase converter pf the polyphase motor type, adapted to receive energyrfrom thesingle phase source oi su ply and deliver energy to the polyphase loa and means, in-

V cludlng a plurality of current responsive devices operatively'related to the branches of the'polyphase' load and a controller governed thereby, for automatically varying the effecload to maintain balanced currents therein. L

4. In combination, a single phase source, ase load, means,

of supply, a balanced polyp including a phase converter of the polyphase motor type,'ha ving, a plurality of phase windings, adapted to receive ene the single base source of su ply andzieliver y energy to t e polyphase loa from and means, includmg a plum; ity \of current responsive related toithe branches ofthe erned t ere olylphase ad and a controller applied to one phase winding of thephase-converter. a y

5. In combination, a single phase source polyphase load, means, including a phase converter of the polyphase motor type, adapted to receive energy rom the'singl ephase source of -supply and the polyphase load, and

poly'phasia load, for auto;-

combination with .cuit anda polyphase' load circuit, 0 a phase for automatically varying'the maintaining the polyphase currents I tiallybalanced under allconditi'ons of load. In witness whereof, ,I have hereunto set sponsive devices operatively related to the branches of the polyphase load and a controller governed thereby, for automatically varying the relative values of two of the induced voltages 'in thegpl ase converter. i

6. In, a system oi phase'conversion, the

a single-phase su ply circonverter of the polyphase motor type electrically interposed therebetweemand means comprising an electro-responsive' device operatively for automaticallymaintaining the polyphase currents substantially balanced under all conditions of load,

7. The combination with' a singlephase source" and a polyphase load circuit, of a phase converter of the polyphase motor type electrically interposed therebetween, and

connected to oneof said circuits means comprising an elec'tro-respon'sive device operatively connected to said polyphase load circuit for automatically varying the. effective voltages delive to said loadjcir: .cuit to maintain .bala ed polyphase currents therein.

a 8. The combination with single-phase source anda polfyphase load circuit, of a" phase converter 0 the polyphase motor type electrically connected therebetween, and means comprising a device responsive to-current in 'said' load, circuit for automatically my. hand this first day oi:

' nnnslr F. ALEXANDERSON.

substan-

Images