US2585050A

US2585050A - Variable transformer

Info

Publication number: US2585050A
Application number: US69761A
Authority: US
Inventors: Edna M Simon; Clarence J Simon; Herbert A Simon
Original assignee: BEATRICE GEORGE MARTI
Current assignee: BEATRICE GEORGE MARTI
Priority date: 1949-01-07
Filing date: 1949-01-07
Publication date: 1952-02-12
Anticipated expiration: 1969-02-12

Description

Feb. 12, 1952 A, SlMON 2,585,050

VARIABLE TRANsFoRMER Filed Jan, Y, 1949 -2 sHEETs--SHEET 1 uuml "MM (torneg Feb. 12, 1952 A. SIMON 2,585,050

' VARIABLE TRANSFORMER Filed Jan. 7, 1949 Y 2 SHEES--SHEET 2 Gtfomeg Patented Feb. l2, 1952 VARIABLE TRANSFORMER Arthur Simon, deceased, late of Milwaukee, Wis.,

by Edna M. Simon, Clarence J. Simon, and Herbert A. Simon, executors, Milwaukee, Wis., assignors to Beatrice George Marti, Wauwatosa,

Application January 7, 1949, Serial No. 69,761

Claims. (Cl. 171-119) This invention relates to improvements in variable transformers and particularly to transformers in which the ratio of transformation may be changed by varying the inductance between the primary and secondary windings while maintaining the reluctance of the magnetic circuit substantially constant.

It is one object of the present invention to provide a variable transformer in which the output voltage may be easily varied responsive to changes in load or to any other changes in the circuit supplied by the transformer.

Another object of the invention is to provide a variable transformer of which the output may be continuously varied rather than varied in steps only.

Another object is to provide a variable transformer applicable to high voltage circuits but without contacts carrying high currents.

Another object of the invention is to provide a variable transformer in which the value of the secondary or induced voltage may be changed without phase displacement between the primary and secondary voltages.

Another object of the invention is to provide a variable transformer with a minimum of reluctance in its magnetic circuit and in which the reluctance is maintained substantially constant at all times.

Another object of the invention is to provide a variable transformer with relatively low magnetizing current and magnetic circuit losses.

Another object of the invention is to provide a variable transformer in which the windings are all substantially in planes and in which the adjacent surfaces of the cores are also substantially planes for ease in construction.

Another object of the invention is to provide a variable transformer with one portion rotatable relative to another portion and in which it is no longer necessary for the rotatable portion to be kept coaxial or concentric with the stationary portion and in which the magnetic forces act parallel to the axis of the rotatable portion, which simplifies thc maintaining and operation of such portion.

Another object of the invention is to provide a continuously variable transformer which is easily adjusted, of high eiliciency, of a minimum size for a given capacity, which is simple and inexpensive in construction, in which there are no circuit making and breaking contacts and whichI will be vibrationless and noiseless.

Another object of the invention is to provide a variable transformer readily adaptable to either single phase or polyphase systems.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing in which:

Fig. l is a vertical sectional view showing the invention embodied in a single phase transformer;

Fig. 2 is a view looking at one end of the rotatable core and coil sub-assembly, rotated 90 from the position in Fig. 1

Fig. 3 is a view looking at one end of the stationary core and coll sub-assembly, rotated 90 from the position in Fig. l

Fig. 4 is an exploded perspective view of the stationary core and coil sub-assembly.

Fig. 5 is an electrical line diagram showing the use of the present variable transformer as a feeder voltage regulator;

Fig. 6 is a view of one end of the stationary core and coil sub-assembly of a polyphase transformer.

Fig. 7 is a view of one end of the rotatable core 1nd coil sub-assembly of a polyphase transormer.

Fig. 8 is a series of diagrams showing the magnetic and voltage relationships between the coils at different relative positioning of the rotatable I plane surface with grooves diametrically of the core and at right angles to each other. The windings are mounted in the core grooves and divide the end of the core into pole surfaces which are defined by the exciting windings and the compensating windings mounted below the excited windings.

A support which is preferably non-magnetic, is formed on or mounted in the stationary yoke and extends through the aperture in the stationary core to act as an axle for a. rotatable portion. Such rotatable sub-assembly comprises a yoke also preferably of non-magnetic material and on which is mounted a cylindrical spirally wound core having one end formed as substantially a plane surface and having a diametric groove formed therein from such surface to receive secondary or excited windings. 'I'he yoke of the rotatable portion has a bearing for mounting such portion on the axle to bring the finished ends of the cores into contact. Suitable means are provided for oscillatory movement of the rotatable portion relative to the stationary portion in response to changes in load on, or to other conditions in the circuit connected with the secondary windings.

Referring to the drawings, reference numeral Il designates the yoke of the stationary portion which is preferably of non-magnetic material and is generally of spoked wheel-like form. The yoke has a flange I I and a central boss or hub I2 with an aperture therein, the flange and boss defining an annular space in which is mounted a core Il of magnetically permeable, strip material wound spirally to form a hollow cylinder fitting into such space. Suitable means are provided for retaining the core in its wound condition and for retaining the core in place on the yoke. One end of surface I1 of core Il, is preferably finished as a substantially plane surface at right angles to the axis of the core. Grooves It and are formed in the core from the nished end thereof, and are on diameters of the core and at right angles with each other.

Windings

23 and 24 are placed in the groove i9 and about the core periphery for severally enclosing portions ofthe core end i8 to form

magnetic pole portions

25 and 26 when the windings are energized. Other windings 21, 23 are placed in the groove 20 below `

windings

23, 24, and about the core periphery to compensate for stray flux as will be explained hereinafter.

A post 3l of non-magnetic material, is ilxed in the aperture in yoke boss l2 as by use of a pin 32, to extend substantially centrally through the aperture in the core Il. The post serves as an axle on which is mounted a bearing 33 in a yoke 31. The yoke 31 is also preferably of nonmagnetic material and is even more nearly of wheel-like form than yoke Il. Yoke 31 has a peripheral flange` 3l and an apertured cylindrical boss or hub 39 for receiving the bearing 33. A

core 43 of spirally wound magnetic strip is formed as a hollow cylinder and is retained in the annular space between the yoke flange 33 and the boss 3l, the core 43 being similar in internal and external diameter to the core I1 and having its end surface 44 formed either as substantially a plane or with a peripheral flange 45. A ,groove 4l is formed in the core 43 from the end surface 44 and on a diameter of the core to receive windings 4I and 49. Such windings form the secondary coils or excited windings of the transformer, in which a voltage is induced and such windings deiine magnetic poles 5I, li similar to the

poles

25, 24.

It will thus be seen that both cores are easily and quickly made with no waste whatever of material. It is made easier to finish one end of the cores to any desired degree of planeness than to finish core surfaces of any other configuration. The coils are formed in planes so that the coils also are easily and cheaply made and are readily placed in proper relation in the cores and in proper relation to one another.

Cores I3 and 43 may be in contact over their entire core ends i1 and 44 thus reducing the air gap between the cores to one to two-thousandths of an inch depending on the degree of planeness of the core ends. But the rotatable sub-assembly of the transformer rests on and is to be movable relative to the stationary sub-assembly, through a portion of a revolution about the axle 3i.

a,sss,oso Y i Hence. it may be desirable to provide one of the coreswithabearingiiangeasatu toreduee the area of actual contact between the core ends. which reduced area may then be lubricated. The amount of relative movement between the two sub-assemblies depends on the number of magnetic poles employed, the movement required for the full range of transformer adjustment. for a two-pole device being of rotation and the movement for a four-pole machine being two times 45 of rotation, etc.. there being only the limit of practical usable diameter on the number of poles used.

Suitable means such as a gear segment Il mounted on the periphery of yoke 31, may be engaged with gearing driven by any known type of reversible electric motor controlled by means such as any known contact making and breaking meter, responsive to increase or decrease in volt age in the circuit supplied by the secondary windings 4l, 4I. The amount and rate of movement of the rotatable transformer portion being relatively small, it is desirable that speed reducing means be used in the drive, which makes it possible to use a relatively small driving motor.

In the present structure, the yoke Il is extended to form a base, or has connected therewith a base I4 for a motor Il driving a worm l1 meshing with a worm wheel Il on a shaft I3 supported in a boss 44 on the base. The worm wheel It is connected with a gear 4| meshing with the gear segment Il on the yoke 31 of the rotatable subassembly. The gearing is also preferably of non-magnetic material to co-act with the post 3| in avoiding a closed magnetic circuit between the yokes Il and 31, if such yokes are not themselves formed of non-magnetic material. It is, of course, understood that all of the ilux is to pass through the cores and not through the yokes or any other portions of the device. It will be understood that the present operating means is i merely one of a number of such means which may be used because all magnetic forces in the present device are axial of the cores, only a small movement is required, a relatively small weight is to be moved, the movement is at low speed, and because of many other favorable factors in the present device.

When the present device is used for feeder voltage regulation, it is connected as shown in Fig. 5 in which a source il of alternating current is connected to the ends of the

primary windings

23, 24 which are joined with each other. One side of the alternating current supply circuit is connected with a load 4I and the other side of the supply circuit is connected through the Joined

secondary windings

43, 44 with the other side of the load 44. The compensating windings 21, 2l are short-circuited as shown.

When the

primary windings

23, 24 are energized, the core i6 is magnetized as a horseshoe magnet" with poles 25 and 2l forming oppodte magnetic poles. Of course, being energized by alternating current, reversal of the current reverses the polarity during each current cycle. When the

primary core poles

25 and 24 are opposite the secondary core poles 5I and Il, flux passes between the pairs of opposite polarity poles and induces a voltage in the

secondary windings

48, 49. The air gap between the poles of the several cores is constant and may be made a very small fraction of an inch dependent only on the degree of planeness of adjacent core ends. Thus the reluctance of the magnetic circuit is minimized, and is constant, which contributes to the high ei'ilciency of the present structure.

The electrical operation of the device can be most readily understood by referring to the diagrams forming Fig. 8, to which are applied the reference numerals heretofore used. The cores are shown as rectangular and as reciprocably movable relative to each other and only one excited or secondary winding and one compensating winding are shown, for ease in illustration. The flux F directly linking a primary and a secondary coil and the flux f not directly linking such coils, are shown in dotted lines and the voltage induced in

secondary windings

48, 49 is shown by dot-dash arrows.

When the cores I6 and 43 are positioned as shown at A (in Fig. 8) with the

primary windings

23, 24 energized, the flux F produced by

windings

23, 24 is intcrlinked with

secondary windings

48, 49 to induce a maximum voltage in such windings in the direction of the arrow V in such diagram. Because of the fact that the cores are actually cylindrical, the flux f is not stray iiux but is also interlinked with the

windings

48, 49 as will be understood if the diagram is conceived with cylindrical cores and in three dimensions. Hence, the induced or secondary voltage is a maximum in one direction and either boosts or bucks the voltage of the supply line dependent on the connections of the present device as is well known, it be" ing assumed that the induced voltage is in phase with the supply voltage in the present position of the parts, and therefore boosts the supply voltage.

When the parts are in position B with

windings

23, 24 energized, the ux F, f induces a voltage in

windings

48, 49 opposite to that produced in position A and of the maximum value in the opposite direction. Hence, the secondary voltage V in position B is 180 out of phase with the supply voltage and bucks such voltage. Any desired value of secondary voltage between the two maximums obtainable in positions A and B, can, of course, be obtained, and such voltage value is iniinitely variable dependent only on the relative position of the parts. In positions A and B, the ampere turns of the primary and secondary windings practically ccmpensate one another.

In position C, it will be seen that the ilux about primary windings 23, 24-links equally and in opposite directions with the secondary windings 48,

49 thus endeavoring to induce equal and opposite voltages in such secondary windings. But the net eiect is zero voltage in the secondary windings even though the flux fully interlinks the primary and secondary windings. Hence, it will be seen that any secondary voltage from maximum in one direction to maximum in the other direction can be obtained by continuous variation from one maximum value through zero to the other maximum value.

But in position C, the ampere turns of

primary coils

23, 24 are not opposed by the same number of ampere turns of

secondary coils

48, 49 so that a considerable indirectly linked flux would result, which is undesirable. Such flux is avoided by the use of compensating windings 21, 28 as shown in position D. The action of such compensating windings is well known and need not be particularly described herein. However, the compensating windings have the effect in the present device of eliminating forces acting at an angle to the axis through the coils.

When a polyphase device is desired, the primary core I6 may be made as shown in Fig. 6 for three phase use, in that it is grooved to receive a number of pairs of windings 10 and 1|, 12 and 13, and 14 and 15 for the several ones of the three phases and to receive compensating windings 16, 11 and 18. The secondary or rotating sub-assembly oi the device includes core 43 and

windings

82, 83 and 84 for the three phases desired. In the polyphase structure above described, the same value of voltage is always induced in the secondary windings but the phase position of the voltages is varied thus controlling the voltage supply to the load. A polyphase unit may be connected in delta or star as is well known, to obtain the desired phase relation. It will be understood that the number of poles utilized may be varied as desired merely by changing the diameter of the cores so that the device is readily adaptable to any required load. Increase in the number of poles produces maximum utilization of the cores and a higher eiliciency of the device.

It will be understood that a three-phase device may also be obtained by providing threesstructures such as are described in detail herein. Such multiplied single-phase device requires only that the several units be spaced sufficient distances to avoid the production of stray flux fields interfering with the operation of the several units. Any desired phase relation between the several units may be obtained by delta or star connection thereof as desired.

It will be understood that a plurality of wind ings per pole may be used thus increasing the capacity of the device and that such plurality of windings may be in side by side relation or may be fiati-cned and twisted so as to be placed one above another. The material of the cores may thus be utilized to any degree desired merely by increasing the number of windings used per phase. Even in Figs, 6 and "I, the utilization is only 50% and increase to 75% is obtainable merely by use of four primary windings per phase (spaced 120), and corresponding secondary windings. The windings will be connected in series or parallel or series-parallel as desired.

Also it is possible to increase the capacity of a unit by using three cores with the intermediate core rotatable relative to the two end cores and with exciting or primary windings in both the end cores and coacting with excited windings in the two ends of the intermediate core. Such increase in capacity does not increase the size of the driving means required as is usual with other constructions.

It will be seen that the present construction provides a variable transformer in which the cores are easily made, requiring the nishing of only one end of each for reducing the air gap in the magnetic circuit to a minimum and thus minimizing the reluctance of the device. The Windings are planar and are placed in planes which simplifies the construction thereof and the assembly of the device. All forces are axial of the device and press the cores together so that the yoke structure is simple and the drive for securing rotation may be small and simple. The cores are always in contact so that the device is absolutely noiseless. Either one of the core-coil sub-assemblies may be made movable as desired.

The magnetizing current required and the magnetic losses are low so that a high eiiciency structure is obtained. The output voltage varies only in amount and there is no undesired phase displacement in the device which would produce a poor power factor, and the voltage is continuously variable by any desired amounts. There are no contacts carrying high currents and the device can be made as sensitive as desired to load circuit variations. ly simple and highly effective electrically at relatively low cost and with the minimum of operating and maintenance difficulties.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

1. In a variable output voltage transformer, a pair of cores each having a face adapted for movement in contact with a face of another core to provide a constant and minimized airgap between the contacting core faces, the cores being grooved from the contact faces, a plurality of primary and secondary windings severally mounted in the grooves of the core, a plurality of shortcircuited windings in the grooves of one core for compensating the stray flux of the secondary windings upon movement of the primary and secondary windings relative each other into positions of indirect ilux linkage therebetween, and means for` moving one core and the windings therein relative to the other core responsive to voltage variations in the secondary windings and while the core faces are in contact.

2. In a variable output voltage transformer, a pair of cores severally having a single face adapted for movement in contact with each other to provide a constant and minimized airgap between the core faces, the cores being grooved from the contact faces, the one core being supported wholly on the other core in superposed relation and movable thereon, a plurality of primary and secondary windings mounted in the core grooves, a plurality of short-circuited windings in the grooves of one core for compensating the stray flux of the secondary windings upon movement of the primary and secondary windings relative each other, an electric motor responsive to voltage variations in the secondary windings, and speed reducing means connecting the motor with the upper core for moving said core and the windings therein relative to the lower core and while the core faces are in Contact.

3. In a variable output voltage transformer, a pair of cylindrical cores in base-to-base contact, one base being pressed on the other core base, the contacting bases being grooved and substantially planar for movement in contact with a base of the other core to provide a constant and minimized airgap between the contacting core bases, a plurality of primary and secondary wind- Hence, the device is mechanicalings each mounted in the grooves of one of the 4. In a variable output voltage transformer. a pair of cylindrical cores, one core being superposed on and supported wholly on the other core in basetn-base contact, the contacting core bases being grooved and substantially planar for movement in contact with the base of the other core to provide a constant and minimized airgap between the contacting core bases, a plurality of primary and secondary windings, the windings being severally mounted in the grooves of one of the cores, a plurality of short-circuited windings in the groove of one core for compensating the stray ux of secondary windings, means for maintaining the cores in vertical axial alignment, and means for moving one core and the windings therein relative to the other core responsive to voltage variations in the secondary windings and while the core bases are in contact.

5. In a variable output voltage transformer, a pair of hollow cylindrical cores adapted for mounting in vertical alignment, with one base of the pair of cores in contact, and with one core superposed on the other core, the contacting bases being substantially planar and having grooves therein, the one core wholly supporting the other core for providing a constant airgap between the adjacent core bases, a plurality of primary and secondary windings in the core grooves, a plurality of short-circuited windings in the grooves of one of the cores for compensating the stray flux of the secondary windings upon movement of the primary and secondary windings relative each other, a plurality of yokes severally flanged to define an annular space, the yokes severally having central apertures therethrough, a post in the apertures for retaining the yokes in substantially parallel relation, an electric motor responsive to voltage variations in the secondary windings, and speed reducing means connecting the motor with the upper core for moving said core and the windings therein relative to the other core.

EDNA M. SDON. CLARENCE J. SIMON. HERBERT A. SMON.

Eecutors of the Last Will and Testament ol Arthur Simon, Deceased.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 742,548 Wright Oct. 27, 1903 1,445,242 Shakelton Feb. 13, 1923 1,471,863 Riegger Oct. 23, 1923 1,613,222 Curtis et al. Jan. 4, 1927 1,790,746 Fischer Feb. 3, 193i 1,984,939 Nachumsohn Dec. 18, 1934 1,995,637 Day Mar. 26, 1935 FOREIGN PATENTS Number Country Date 246,929 Great Britain Feb. 8, 1926