US1356934A - Multispeed induction-motor - Google Patents

Description

C. MACMILLAN.

I MULTISPEEDI INDUCTION MOTOR.

APPLICATION FILED MAY 31, 1917. 1,356,934. Patented Oct. 26, 1920.

4 SHEETS-SHEET 1.

r a m u l n B q w w %L w a D. .DIL A. w PW .m I. MN "w m F r I II W M M a .a a a vp I 1.0 0 "m a .P L 0 w l U .D p b H a 5 "w 1 a i c P W l Ill-b G lli-Tw l 7 a P 4 a 0 ABC .Q. PQ P Q 4 w 7% M NV 2 o i H m m F 5 Campbell macmillan, b5 MM l-lis Attorney.

C. MACMILLAN.

MULTISPEED INDUCTION MOTOR.

APPLICATION FILED MAY3I,1917.

Patented Oct. 26, 1920.

4 SHEETS-SHEET 2.

m mw ,ll||||||J\ [llillllijj a M 4 C\\ y c u o A b a R C a b].

J M Q a 0 Al. 4 x1 F.

Inventor Campbell Macmillan,

b8 H is Attorney.

4 SHEETSSHEET 3.

Patented Oct. 26, 1920.

fiIQ/It/6}70/6 6d W I, Left-32po/e 5d C. MACMILLAN.

MULTISPEED INDUCTION MOTOR.

APPLICATION FILED MAY31, 1917.

La /H; H is v Attorney.

uuuuu Inventor 7 Campbell macmil Ian,

'35., innnnnnnnnnnnnnnnnnnnl'lnn C. MACMILLAN.

MULTISPEED INDUCTION MOTOR.

APPLICATION FILED MAY 31. 1917.

356,934. Patented Oct. 26,1920.

4 SHEETSSHEET 4- n-poles 6 a -poles Q4) 2 Inventor": Campbell Macmillan,

WWW

H is Attrney.

UNITED STATES PATENT OFFICE.

CAMPBELL MACMILLAN, 0F SCHENECTADY, NEW YORK, ASS IGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MULTISPEED INDUCTION-MOTOR.

Specification of Letters Patent.

Patented Oct. 26,1920.

Application filed May 31. 1917. Serial No. 171,915.

duction motors and has for its object the provision of an improved multi-speed inductlon motor. My invention more particularly relates to multi-speed induction mo-- tors of the type described in my copending application for Letters Patent of the United States, Serial No. 171,916, filed May 31, 1917. In this connection, the object of my invention is to provide an induction motor having a primary winding with simplified connections for producing substantially sinusoidal or balanced primary magnetic fields of different pole numbers when connected to polyphase systems of energy distribution of different numbers of phases. Other objects of the invention will be brought out in the course of the 'following description.

I have described in my aforementioned application a multi-polar induction motor having a primary winding arranged to produce primary magnetic fields of different pole numbers when suitably connected to polyphase systemsof energy distribution of different numbers of phases. I particularly described a primary winding arranged to produce primary magnetic fields of either 72 or 2% poles when suitably connected to a polyphase system of three-phase electromotive forces and a'primary magnetic field 3n 0f 3 polyphase system of quarter-phase electromotive forces. The particular aim of my present invention is to provide a more simple arrangement for effecting the necessary circuit connections in such a combination poles when suitably connected to a comprising a source of polyphase energy phase when the primary winding is arranged for one pole number to a common neutral, and, considering the opposite ends of all coil-sections, to connectthose coil-sections which are in the same phase when the primary winding is arranged for the second pole number to a common neutral. The common connections at one end of the coils sections then serve as terminals for one pole number of the primary winding and the common connections at the other end form a complete set of neutralor Y-points, while for the other pole number the latter common connections serve as terminals and the first mentioned common connections form a com-' plete set of neutral points.

The novel features of the invention which I belleve to be patentable are definitely set .forth in the appended claims. Theprinciple of the invention, together with the construction and mode of operation of induction motors and systems embodying the same, will be best understood from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a diagrammatic assembly of a system of electric ship propulsion embodymg the present invention; Fig. 2 is an explanatory legend-diagram; Fig. 3 is a diagram of the electrical connections of the system of Fig. 1; Figs. 4.- and 5 are explanatory vector diagrams Figs. 6 and 7 are explanatory diagrams of the different connections of the motor shown in Figs. 1, 2 and 3; Fig. 8 is a diagrammatic view of a modified form of the invention; Fig. 9 is a diagrammatic view of a further modification of the invention; Figs. 10, 11 and 12 are ex planatory diagrams of the difi'erent connections of the primary winding of the motor represented in Fig. 9; Fig. 13 is a diagrammatic view of another modification of the invention; and Fig. '14 is an explanatory dia ram.

he present invention is of particular ad- Vantage in electric systems of ship propulsion, and in Fig.1 I have illustrated such a system comprising an elastic-fluid turbine 15 directly coupled to an alternating current generator 16. A multi-speed induction motor 17 has its rotor mounted on the shaft 18 of one of the ships propellers 19. It will of course be understood that the entire equipment will generally consist of a plurality of ropellers and induction motors, and usuali; will include two or more turbine-driven' generators 15-16. The propellet-tithing motel" 1? is o'tesigmedi toe poie= changing in order toprovisie two efiicient speed ranges of navigation. eeeordenee with my meseht invention, the Winding CU: the motes 1? is prone? with very simple connections for pemiuemg pr msry magnetic fiehts o ciifierent poie numbers when supphed 0; th with poiyohese oi 1 tion of em;

The primery winding of the so-eeiieai three-phase meter usueiiy Wound six-phase with is obteh oil by otwo phase-belts 1B which U current flow seietiwiy pieced 180 ing to each at the t "a; 1 of sup iy, The belts are dis sti'ieei degeees and called a 66 six-12h Such e. Winding is sented by row U:

t, e of 2, Where it 6 g0. The ietters pho-se-beits or eat phase A and tiveiy opposite in (2 degrees out of ph the eorrespontiing f ,SS-o phese B, emit e e the eeriespoedihg phase-belts connected to phase C, Ah of the phase-h the same phase may electrically connected together any suitable mealtimes for example, iii series, in pereiiei or: partly in series and pertiy pg eliei, es W312i he omteestooii by those s2.

the es 7 The seeomi i resents the errengemeet of the sits connected to primary Whese" ee has the same numhei: of e- 3 belts of then-pole W In the showings, g ere, therefore, the phese heits e: n-poie v n Winding n m 1.1 v. me if trfieei degrees out of phase with seeeeee The i'eletive pitch of the primary coiis v J. .L 4 s q 4?. go ee-oeh, must undergo in pessig x one arrangement to o1. 'lhe w 4.1. :2 Q i posse-belts which undergo eel mange in passing i nt to the other may be ei CO1 in e single gimp, emi it W- s from eii'inspeetioe Fig. 2

Wiii be twelve of such T3853 designated by the legends be hues to mheete the p I H1 their connections W ie numbers of primary .1 iengeci. Thus, a is eoniieet ese for the n-poie arrangement 5 the positive terminal of Eehese 1 for the q -poie arrangement; group 5g is connected phase B so as to carry ce ent 6Q eieethe oureent in phase-halt a for the n-poie arrangement enci to the positive terminoi of phase Q1 '50? the phase C so as to deny current 120 eieetrieei oiegrees out of phase with the current iii phase-belt a for the 'vpole arrangement ens to the negative terminei oi phase P foe 3e J 1 e =peie emengemeeo, ELLE; so on tn teeminei A, the coii-seetioes 5 end here connected to the common tei'miiiei B and the coil-sections e and e we co men terminal eo1i-seet1e ewengementg group 5 is GGBHGOEQCi '4 when quarter-phase currents are supplied to the terminals P, R1] and Q, the primary winding will be arranged as a -pole, quarter-phase, three-circuit diametrical winding. These circuit arrangements Wlll be more clearly seen after a discussion of Fig. 3.

Lhe electrical connections of the system of Fig. 1 are shown in Fig. 3. p The primary winding of the motor is divided into twelve circuits or groups, just as explained in con- 'nection with Fig. 2. These groups are designated by the ame legends as in Fig.2. The common terminals or neutrals are likewise designated by the same reference letters as in Fig. 2. The armature winding of the generator 16 has four coil-sections 40, 41, 42 and 43, which are 60 electrical degrees apart,

and four coil sections 4.4, 15, 46 and 47,

nated by the same reference characters as the corresponding coilsections of Fig. 3. The connections oi the twelve groups of the primary winding of the motor for this position of the switch 21 are shown in Fig. 6. When the switch 21 is thrown to its upper position, the armature circuits of the generator are connected as a two-circuit inde pendent. quartenphase winding to the quarter-phase terminals P, F, Q and The vector diagram of the generator winding for this connection is represented in Fig. 5, and the connections of the primary winding of the motor shown in Fig. 7

It will be observed that the switching mechanism for polie-changing becomes very simple by the use or" my present invention. Only seven terminals are brought out from the multi-polar induction motor. The quarter-phase terminals are provided with a reversing switch 22, since in ship propulsion reversal will oniy be carried out with the low speed polar arrangement, that is with 3% -poles.

In Fig. 8 of the drawings, I have shown a multi-polar motor adapted to be supplied with polyphase systems of energy distribution of three and six phases. Following the procedure outlined in Fig. 2, it will 'be evident that in the most general case of n and m primary magnetic poles, the primary windingmust be divided into eighteen circuits or groups. The phase-belts for the three-phase arrangement I will designate a .Z), c and for the six-phase arrangement a, I), c, 6 b, E, and the eighteen groups are designated by characteristic legends following the system used in-Figk2. All of the phase-belts a for the -n-pole three-phase arrangement are connected at one end to a common terminal A, and similarly with respect to phase-belts Z) and 0. The other ends of the phase-belts are connected to six terminals so that the same phase-belts for the m-pole six-phase arrangement are connected to the same terminals. The motor, accordingly, has only nine terminals. The armature winding 26 of the supply generator is delta connected for three-phase and diametrical for six-phase. A single switch 27 with six double-throw blades effects the necessary changes in the enerator and motor circuits for changing rom n to m poles, or vice'versa. When this switch is in its lower position, the generator is three-phase delta-connected to the motor terminals A, B and C and the primary winding of the motor produces a primary magnetic field of n-poles. lVhen the switch 27 is in its upper position, the generator is connected to deliver six-phase electromotive forces to the motor terminals a, I), c, d, b, and E, and the primary winding produces m poles.

The multi-polar motor or my present invention may have a secondary winding of any suitable t pe. The simplest type of secondary win ing would be a low resistance squirrel cage winding, but for installations where speed control or increased torque is desiredthe secondary winding may be phase-wound and arranged for connection to an external resistance. Where increased torque for particular conditions of operation are required, as for reversing in ship pro pulsion, a double squirrel cage secondary winding may be of advantage, as explained in Letters Patent of Ernst F. W. Alexanderson, No. 1,215,095, patented Feb. 6, 1917. Increased torque of the motor may also be obtained in the manner described in my copending application for Letters Patent oi the United States, Serial No. 171,917, filed May 31, 1917. Such a modification of the present invention is illustrated in Fig. 9.

The row of short heavy vertical lines in Fig. 9 represents the centers of coil-sections or phase-belts of the primary winding of a multi-speed induction motor, as described in connection with Fig. 2. In the motor of Fig. 9, n is equal to 16 and is equal to 24.

In addition, the coil-sections of this winding are arranged to be connected as a 32- pole threephase primary winding. The arrangement of the coil-sections for this 32- pole connection is represented by the last row of legends a, b, a, a, etc.

The polyphase systems or energy distrihution otdiherent nnmhers at phases are produced by a generator whose armature winding 22 is a three-phase star-connected winding. One phase winding of the generator is divided into two sections 60 electrical degrees apart. The circuits and connected'in diametrical independent circuits for quarter-phase. The generator switch 23 is a five-unit doulole-throw switch and in changing the generator circuits fnom three-phase to quartenphasealtersthe voltage per phase of the generator in the-ratio of l to 0.71. In other words, the terminal voltage of the generator when tarnishing quarter-phase electromotive forces is 71% tit? of its terminal voltage,2 when inrnishing three-phase electroniotive tor-cos.

In accordance withthe principle of my i present invention, all: ot the phase-helts o with respect to the 32-pole arrangement are connected at one end to a common terminal A, and the phaseheltsh and c are similarly connected to common terminals B and C, r spectively. Considering now "the Qt-pole quarter-phase arrangement, all of the basebelts are connected at their other on s to a common terminal 1?, andall oi" thephasehelts 37 are similarly. connected to a common terminal P. The common terminal Q is made up of three terminals a, ii, a, and the common terminal is similarly made up of three other terminals d, h, c. A loan unit double-throw switch 24: is provided for connectin the'three terminalso, h, c of terminal Q 6;, l5, c of terminal Q together when the switch is in its lower position. When the switch is in its upper position, it connects the two terminals 6 and a together, and similarly the two terminals 5 and h and E and c.

A. second motor switch 26 isprovided. In its right-hand position this switch connects the three-phase suoioly system to the motor terminals A, 1%, and in its lefthand position it connects the three-phase supply system to the notor terminals 5/ h 5'.

he manipulation of the switches 23, 24. and 26 to eilect the din erent operating conditio'ns of the system is as follows: For capole quartenphase operation or the motor the switch 23 1S thrown to its le'lthand the motor circuits for 32 active. ciated with the eleven terminals of the motor together and the three terminals incense ation of the motor, the generator switch 23 is thrown to its right-hand position, and the motor switches 24 and 26 are thrown to their lower and right-hand positions, respectively. 'lhe groups of the motor winding are then arranged as indicated in Fig. 11. For the 32-pole three-phase operation oi the motor, the generator switch 23 is in its righthand position, and the motor switches 24 and 26 are in their upper and left-hand positions, respectively, he arrangement of poles is shown in Fig. 12. It will he ohserved that these three polar arrangements are obtained with only eleven motor terminals. The twelve groups of the motor winding are designated in liigs. l0, l1 and 12, by characteristic legends op, =1:

cg, etc., to designate the changes iii-the connections of the groups for the three dih'erent olar arrangements. These characteristic egends are derived icom the legends of Fig. 9, as will he clearly understood in View of preceding explanations i In accordance with the invention of my alorementionedap lic'ation Serial l lo. 171,917, the primary winding of the motor represented in Fig. 9 is divided into two components such that when one component is disconnected fromthe source 01 supply alternate sections emhracing 4:, 6 or 8 poles, according as the primary 'windin is connected for 16, 2d or 32 poles, are i is or in- To this end switches 25 are assoso as to disconnect these alternate sections of the primary winding from the source of supply. A compound or double secondary winding is provided, one section oi which is of low resistance and the other section of high resistance. in Fig. 9 of the drawings, 1 have shown a high resistance squirrel 'cage'winding 20 and a low resistance secondary winding 31 arranged so that when alternate sections of the primary winding Lido tors corresponding to idle sections of the primary wmding are included by transferiner action as a part of the secondary ing of the motor.

The coils of the winding 31 are connected to two sets of collector rings and 3 1 so that with respect'to 2d orimary magnetic poles this secondaq'" w has twelve circuits connected in 2 collector rings 33 and similarly twelve circuits connected in parallel between the rings 34. For the sake of clearness, onl the connections to the collector rings 33 ave been fully indicated in the drawings. Every coil or group of coils beneath phase-belts p are 17 are connected in series to the similarly positioned coil or group of coils six polesremoved with respect to the 24-pole arrangement, and the terminals of these series connected coils or groups of coils are connected to the collector rin s 33. The coils benzath phase-belts g an Q are similarly connected to the collector rings 34. For the motor of 24 poles, there will, therefore, be twelve of these series-connected coils or groups of coils connected to each set of collector rings 33 and 34;. The transformer action between the low resistance winding 31 and the high resistance squirrel cage winding 20 is obtained by open-circuiting alternate sections of the primary winding embracing six adjacent poles.

It will be observed that the low resistance secondary winding 31 is eilectively opencircuited for a primary magnetic field of 24 poles. This winding might, therefore, remain entirely inactive for this polar arrangement and all of the secondary currentwould then be forced to flow in the high resistance winding 20. Generally, however, it will be more desirable to provide external resistances 35 arranged to be connected between collector rings 33 and 34, respectively, and thus to complete thev circuits of the winding 31. The resistances 35 may be adjustable and when entirely out out so as to short-circuit the rings 33 and 34;, respectively, the winding becomes electrically equivalent to an externally short-circuited' low resistance winding.

Although the winding 31 is efi'ectively open-circuited for 2 i-po es, it is internally short-circuited for either 16 or 32 poles. For the 16-pole arrangement, the coils beneath phase-belts a, b and 0 are connected to the collector rings 33 to form in efi'ect a short-circuited star-connected winding and the coils beneath phase-belts a, t and 2: are similarly connected to the collector rings 34:. For the 32-pole arrangement, the winding is similarly a short-circuited, star-connected winding. The only difference between the short-circuits for the 16- and 32- ole arrangements is that for 32 poles t e p and g circuits connected to the collector rings 33 and 34, respectively, carry currents in the same direction, while for 16 poles the currents in these p and q circuits are 180 electrical degrees apart.

In Fig. 13 of the drawings, I have represented a modified arrangement of connections for such a system as illustrated in Fig. 9. The two 120 degree (or 60) circuits of the generator winding 27 are independent and have two terminals each brought'out to a six-unit generator switch 28. The two 30 degree (or 150) circuits of the enerator winding are also independent an their four terminals are brought out to the switch 28. A five-unit double-throw switch 29 is also provided. The phase-belts p, 17, q and q of the pole arrangement of the motor of the system is as follows: For g-poles with a quarter-phase source oi. energy, the

switch 29 is in its off position and the switch 28 is in its left-hand position. The arrangement of the twelve groups of the primary winding is then substantially the same as in Fig. 10, the only difference being that the neutral point connections shown in Fig. 10 are not made in the motor of Fig. 13. For n-poles, the switch 28 is thrown to its right-hand position, and the switch 29 is thrown to its left-hand position. The twelve groups of the primary winding are arranged for this connection substantially the same as represented in Fig. 11. For 2'n-poles, the switches 28 and 29 are both in their right-hand positions, and one terminal (A) of each phase winding of the generator is connected to the alternate corresponding phase-belts (a) of the motor, while 'theother terminal (A) of the same generator phase winding is connected to the other corresponding phase-belts (a) of the motor. A diagram of the electrical connections of the generator and motor circuits for 2n-poles is shown in Fig. 14 of the drawings. The same rotor as illustrated in Fig. 9 may be used with the motor of Fig. 13.

I have herein shown and particularly de-' scribed certain embodiments of my invention for the purpose of explaining its principle and showing its application, but numerous modifications of the details of construction and arrangement of these embodiments and other applications will present themselves to those skilled in the art. I, therefore, wish to cover by the following claims .all modificationslwithin the spirit of the invention.

What ll claim as new and desire to secure by Letters Patent'of the United States, is

1. A multi-speed induction motor having a primary'winding arranged so as to produce balanced primary magnetic fields of. n

and pole numbers when supplied from three-phase and quarter-phase systems oil energy distribution respectively, said primary winding comprising a-plurahty of circuits each of which contains conductors which carry current relatively in the same ill) direction when the primary winding is connected for either one of said diflerent pole numbers, said circuits being permanently connected for the n and pole numbers so that all the ends thereof, which are tobe connected to the same phase of the threephase system-tor a pole numbers, are connected together while the opposite ends thereof, which are to be connected to the same'phase oi a quarter-phase system for pole numbers, are connected together.

2, A multi-speed induction motor having a primary winding arranged so as to produce balanced primary magnetic fields cit a 3% and pole numbers when supplied from three-phase and quarter-phase systems of energy distribution respectively, said primary winding comprising a plurality of circuits each of which contains conductors which carry current relatively in the same way when the primary winding is connected for either one of said difierent pole numhers, said circuits being connected together so that all circuits which are to be connected to the same phase of a three-phase system for a pole numbers are permanently connected together at one end while the opposite ends-oi said circuits are connected so that all circuits which are to be connected to the same phase of a qu rter-phase system for ca pole numbers permanently connected together,

3, A multrspeed induction motor having a primary winding arranged so as to produce balanced primary magnetic fields of a 3n and E pole numbers when supplied i'rom :v three-phase and quarter-phase systems of energy distribution, said rimary winding comprising a plurality of circuits each of contains conductors which carry current relatively in the same direction when the primary winding is connected for either one of said different pole numbers, said circuits beinrpermanently arranged "for the a and. pole numbers so that there are three four terminals respectively for the fit intense and pole numbers oi the primary winding which respectively term neutral points lor the mary windings. Y

4:. A multi-speed induction motor having a primary winding arranged so as to proand a pole numbers of the priduce balanced primary magnetic fields of n and pole numbers when supplied from three-phase and quarter-phase systems of energy distribution respectively, said primary winding compris ng a plurality of circuits each of which contains conductors which carry current relatively in the same way when the primary winding is connected for either one of said difi'erent pole numbers, said circuits being permanently connected together so that there are three and tour terminals respectively for the a and 3;

pole numbers or the primary winding which 53 2 and a pole numbers of the primary windmg,

v5, A multi-speed induction motor having a primary winding of the multiple layer drum type adapted to be connected as an a respectively form neutral points for the pole six-phase and as e5 2 pole quarterphase winding when supplied' from threephase and quarter-phase systems of energy distribution, said primary winding having terminals, the number of which does not ex- 7 ceed the sum oi the numbers oi phases of till 377, I t -pole siX-pnase winding and as a e pole 2 quarter-phase winding and as a Qa-pole three-phase winding, said primary winding having less twelve terminals, and

means for controlling the connections of the generator winding and the connections between said terminals and the generator arranged to connect the terminals of said pri- 1 mary winding to, said source so as to produce any one oi said polar arrangements or said primary winding.

. 7. A multi-speed induction motor having primary oi the multiple layer I drum type comprising twelve circuits, each of said circuits containing those conductors which carry current relatively in the same way when the primary winding is arranged 3% as an n-pole six-phase winding or as a 2 ing is arranged to produce 1L or 2% primary magnetic poles when connected to a threephase source of alternatlng current energy and so as to produce primary magnetic poles when connected to a quarter-phase source of alternating current energy.

8. A multi-speed induction motor having a primary winding of the multiple layer drum type comprising twelve circuits, each of said circuits containing those conductors which carry current relatively in the same way when the primary winding is connected for any one of three difierent pole numbers, said circuits being permanently connected together so that the primary winding of the motor has less than twelve terminals, and means for connecting said terminals so that said primary winding is arranged to produce primary magnetic fields of three different pole numbers when suitably supplied with alternating current energy.

In witness whereof, I have hereunto set my hand this 29th day of May, 1917.

CAMPBELL MACMILLAN.

Images