Electric power controlling or regulating system

[57] ABSTRACT

An electric power controlling or regulating system comprises a transformer main magnet core portion which forms a first loop opening, a magnetic control core portion forming a second loop opening and magnetically contacting and merging with said main core. The second opening is outside of and separate from the main core opening. Main primary and secondary windings are disposed on the main core portion and pass through the first opening. Control windings are disposed on the control core portion and pass through the second opening while staying free of the first opening. The magnetic flux interlinking the primary and secondary windings on the main core portion is controllable by varying the excitation of the control windings. The second core portion extends either in a plane normal to that of the first loop opening or it extends about the main core portion in the same plane as the latter and has larger dimensions so that the two loop openings are substantially in the same plane.

Claims, 17 Drawing Figures

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ELECTRIC POWER CONTROLLING OR REGULATING SYSTEM

My invention relates to translating systems for transforming, controlling or regulating electric power.

It is known to provide a controllable transformer with a magnetizable core structure composed of two Eshaped components, each formed of a stack of laminations, whose legs face each other and conjointly form a core structure with two loop openings which are transversed by the primary and secondary windings located on the respective center legs of the two E-shaped compnents. Another core member components, the form of a straight bar or plate is interposed between the leg ends of the E-shaped main components and carries respective control windings which pass through the same loop openings as the primary and secondary windings. By energizing the control windings with controllable direct current, the magnetic reluctance in the main core can be changed, thereby varying the degree of the magnetic coupling between the primary and secondary windings. As a result, the system is applicable as a regulating transformer which for a given load in the circuit of the secondary winding furnishes, within limits, a constant voltage or constant current regardless of fluctuations in primary current or voltage.

Tests have been made with such a transformer system for determining whether it would be capable of maintaining the desired regulatory effect, regardless of variations in line voltage up to 15 percent above or below the rated value and load variations from 100 percent down to 25 percent of the rated value. It was found that the system leaves much to be desired under such conditions and that its efficiency under the tested conditions was approximately 48 percent. It was also found that the control coils traversed by direct current have the tendency to overheat.

It is therefore an object of my invention to minimize or eliminate such shortcomings, namely to provide for better regulatability, or higher efficiency, or reduced tendency of heating, or concurrently two or all of these improvements.

It is also an object of the invention to broaden the range of control attainable with transformer systems of the general type described above; and it is a further object to provide in such a system for a closer magnetic coupling between primary and secondary windings.

Another, more specific object of my invention, is to provide a regulating transformer system whose efficiency is increased by bringing the primary winding and secondary winding more closely together than is possible in a transformer system as described above.

Still another object of the invention is to reduce the tendency to heat by spacing the control coils farther apart from the primary and secondary winding, as well as from the core legs on which the primary and secondary windings are mounted.

An object, furthermore, is to secure the desired control or regulation with a minimum of distortion to the wave shape of the alternating current supplied.

It is also an object to achieve the desired performance regardless of changes in frequency of the supply voltage or independently of the particular frequency applied by avoiding any reliance upon magnetic or other resonance phenomena.

To achieve these objects, as well as more specific objects and advantages which will appear from the following description, I provide an electric power transform ing, regulating or the like translating system with a transformer main magnetizable core portion which is closed upon itself, i.e. does not have an air gap, and which forms a first loop opening. I further provide a magnetizable control core portion which forms a second closed loop opening and is magnetically merged with the main core, the second loop opening being outside of and separate from the opening of the main core portion. The primary and secondary windings are disposed on the main core portion and pass through its loop opening. The control coils are disposed on the control core portion and pass through the second opening while staying free of the main core opening. In such a system the magnetic flux interlinking the primary and secondary windings is controllable by varying the excitation of the control coils, thus achieving an improved performance while avoiding the above-mentioned short-comings of the system heretofore proposed.

According to another feature of my invention, the main core portion is composed of two components, of which each is preferably U-shaped and has its two legs facing the respective two legs of the other U-shaped component so that both together form the first loop opening. Furthermore, the second core portion extends in a plane perpendicular to that of the first loop opening and is interposed between the two main core components with the second loop extending away from the main core in the just mentioned plane.

According to another, alternative feature of my invention, the second core portion extends about the main core portion in the same plane as the latter and has larger loop dimensions so that the two loop openings are located substantially in the same plane.

These and other features of my invention, said features being set forth with particularity in the claims annexed hereto, will be described in the following with reference to embodiments of the invention illustrated by way of example on the accompanying drawings in which:

FIG. 1 is a top view and FIG. 2 a schematically perspective side view of a controllable transformer system according to the invention;

FIG. 3 is a front view and FIG. 4 a side view of another transformer system exemplifying the invention.

FIGS. 5, 6, 7 and 8 are respectively different circuit diagrams applicable with transformer systems according to the invention.

FIG. 9 is a top view of still another embodiment.

FIGS. 10 and 11 are respectively a side view and a top view of a modified system embodying the invention.

FIGS. 12 and 13 are top and side views respectively of a further modification.

FIG. 14 illustrates still another modification and FIG. 15 is a circuit diagram applicable with the embodiment of FIG. 14.

FIGS. 16 and 17 illustrate schematic front views of two different types of the system according to the invention.

Referring to FIGS. 1 and 2, there is shown a transformer system whose main core is composed of two Ushaped components 1 and 2 of which each is formed of a stack of laminations. The legs of components 1 and 2 face each other, but are separated by respective laminated control cores 3 and 4, the thickness of each control core being indicated by K in FIG. 2. The main core forms a relatively large first loop opening 5, and each

3,757,201 of the two control cores 3,4 forms a second loop opening 6, 7. The control core portions 3 and 4 and the respective openings 6 and 7 define a plane perpendicular to the loop opening 5 formed by the main core 1, 2. The primary winding P of the transformer system is lo- 5 cated on the legs of the main core component 1, the primary terminals being denoted by A and B. It will be understood that preferably the primary winding P is located on both legs of the main core component 1 although, for convenience of illustration, the primary P 10 is shown on only one of the legs.

The secondary winding S of the transformer is correspondingly located on the legs of the second U-shaped component 2 of the main core, its terminals being denoted by C and D. The primary and secondary windings 15 are thus separated from each other virtually only by the thickness K of the control cores 3, 4. These control cores carry control windings Cl and C2 which extend through the respective loop openings 6 and 7 of the control cores but do not pass through the opening 5 of 20 the main core.

The primary winding P, receiving electric power at terminals A and B from the power line, is coupled magnetically through the laminated core 1, 2 with the secondary winding S, but this coupling is intercepted by 25 the shunting or by-passing effect of the laminated core iron of the control cores 3 and 4 whose magnetic flux path H is at right angles to the flux path J in the main core.

By virtue of the fact that the control coils Cl and C2 ³θ do not obstruct the space available in the opening 5 of the main core, the primary P and secondary S can be placed together much more closely than otherwise possible, thus permitting a maximum of magnetic intercoupling, limited only by the thickness K of the control ³⁵cores 3,4.

In order to bring the primary and secondary as close together as possible, the width N (FIG. 2) of the main core is preferably made approximately 1½ times the core thickness O so that the dimension K of the control cores 3,4 can be kept as thin as possible while still retaining the required cross-sectional area of the control cores. The flux density through the right angle cores 3 and 4 changes the reluctance of the flux path J which passes through the thickness K of the cores 3, 4. As a result, the flux generated by the primary winding P is affected, resulting in an increased excitation current through the primary circuit A-B energized for example by a 60 cycle line voltage. It is, therefore, advisable to keep the thickness K of the control cores 3, 4 as small as feasible and the flux density through the control cores as low as possible.

If, as explained, the dimension N is made approximately equal to 1178 times the dimension O, the thickness K can be kept much smaller than otherwise needed for retaining the area of the shunt cores sufficient for by-passing the flux generated by the primary P and thus reducing the voltage of the secondary S down to the desired level.

The control coils Cl and C2 in the embodiment illustrated in FIGS. 1 and 2 are shown series connected between the terminals E and t⁷. The amount of power transmitted from the primary P to the secondary S is controlled or regulated by varying the magnitude of the flux in the control cores 3, 4 generated by the current flowing through the control coils Cl, C2 between terminals E and F.

One way of supplying the control energy is to apply a controllable direct current through the terminals E and F. In this case, since an alternating current is generated in the coils Cl and C2, they must be so phased that the induced alternating voltages will buck each other so that the alternating voltage between terminals E and F is zero and does not interfere with the control or regulation effected by the direct current supplied through the terminals E and F.

In the embodiment shown in FIGS. 3 and 4, the main core is composed of two three-legged components 11 and 21. The legs 12,13,14 of component 11 have their end faces in proximity to those of the respective legs 22, 23, and 24 of component 21, Two control cores 3 and 4 are interposed between the two components 11 and 21 in the manner explained with reference to FIGS. 1 and 2, except that the two control cores 3 and 4 are immediately adjacent to each other or, if desired, may be formed of a single stack of laminations so that the control cores separate by their thickness K the two center legs 13 and 14 as well as the outer legs 12, 22 and 14, 24. The primary winding P whose terminals are denoted by A and B is located on the center leg 23 of the main core component 21, whereas the secondary winding S surrounds the center leg 13 of main core component 11. The primary and secondary windings P, S extend, and may substantially fill out, the two loop openings formed by the main core assembly. The control windings are located on the control cores 3 and 4 and stay clear of the main-core openings so that the space available within the latter can be occupied more fully by the primary and secondary winding.

The embodiment of FIGS. 3 and 4 is provided with a total of four control windings Cl, C2, C3 and C4 which are disposed on the control cores 3 and 4 and are to be located outside of the main-core openings.

The four control coils Cl, C2, C3 and C4 are all connected in series between the terminals E and F to be traversed by controllable or variable direct current, the ⁴⁰ poling of the control cores being such'that the alternating voltages induced therein will buck and cancel each other. This circuit connection is separately shown in FIG. 5.

₄₅ However, the control coils Cl, C2, C3 and C4 may be so poled for voltage boosting so as to obtain a maximum alternating voltage at the terminals E and F. By providing according to FIG. 6 a control rheostat 27 in the control coil circuit, the induced alternative current ₅θ can be varied by hand or automatically, thereby varying the amount of power transferred from the primary P to the secondary S without requiring the application of a controlling direct current.

As shown in FIG. 7, the rheostat may be substituted ₅₅ or supplemented by a diode 28 or a silicon controlled rectifier (thyristor). The control resistor 29 may also be driven by a phase angle amplifier. Such an amplifier is shown at 31 in FIG. 8. The amplifier controls a thyristor 32 in the circuit of the control windings C1-C4 ₆₀ and is inversely activated by a signal from a current transformer 33, or a voltage transformer if the parameter to be regulated js a voltage. Analogously, the amplifier 31 may be activated by a signa! from a temperature or humidity regulator instead of from a current or volt65 age transformer. In the embodiment of FIG. 8, a potentiometer 34 is shown interposed between the current transformer 33 and the input of the amplifier 31. The load being denoted by 34. In other respects, the circuit

3,757,201 diagram of FIG. 8 corresponds to the modified embodiment illustrated in FIG. 9 and described below.

The system shown in FIG. 9 corresponds substantially to that according to FIGS. 3,4, and 5, except that the primary winding has a main portion Pl mounted on the central leg of the main core in the manner described with reference to FIGS. 3 and 4, while a few additional primary turns P2 are located on the opposite side of the control cores conjointly with the secondary winding S.

A transformer system according to FIGS. 4 to 5 as described above was teated and was found to exhibit an improved power factor at an efficiency up to about 62 percent while affording the satisfactory control and regulation over the entire desired range, such as between 204 and 276 Volt primary voltage. It was further found that the energy required for saturating the magnetic shunts constituted by the control cores and the heat generated in the control cores can be appreciably reduced by connecting the four control coils in the manner described with reference to FIGS. 6 to 8. The provision of the diode or thyristor in the control-coil circuit utilizes only one half of the sine wave for obtaining saturation of the magnetic shunt in the control cores, thereby reducing the amount of energy required to accomplish the desired results.

With a circuitry of the type shown in FIG. 8 and described above, the system is automatically selfregulating. I have it found preferable to place a minor amount of the primary winding turns next to the secondary winding as is schematically indicated in FIG. 8 and shown in FIG. 9. This split arrangement of the primary on opposite sides of the control cores increases the degree of coupling between the primary and secondary windings and thereby improves the regulating range and efficiency. In an embodiment of this type tested, 15 percent of the primary turns were located beside the secondary winding S as indicated in FIGS. 8 and 9. A relative efficiency of about 81 percent was measured.

The embodiment of FIGS. 10 and 11 is essentially a modification of the one described above with reference to FIGS. 4, 5 and 8, except that only two control coils Cl, C2 are provided and located on the mutually adjacent portions of the two generally O-shaped control cores 3, 4 that separate the respective center legs of the main core from each other. The primary winding is composed of a main portion Pl on one side of the control cores and a second portion, comprising only 10 to 20 percent of the primary turns, which is located next to the secondary S on the opposite side of the control cores 3, 4. The two control windings Cl and C2 are connected in series opposition with respect to the alternating voltages generated therein, or they may be connected in mutually boosting relation in the manner and for the purpose described above.

In the embodiment of FIGS. 12 and 13 the main core is composed of two U-shaped components as in the embodiments of FIGS. 1 and 2. The two legs of each maincore component are separated from the legs of the other components by a single O-shaped control core 31. The primary P and the secondary S surround one and the same leg of the main core in the manner apparent from FIG. 12. The primary is subdivided as explained with reference to FIGS. 8 to 11.

An embodiment of the type shown in FIGS. 12 and 13 requires only two control coils, only one main core and only one controlling shunt core, the circuit and mode of operator being the same as described with reference to FIG. 8. This design is most economical to manufacture, although the efficiency is somewhat lower than with the system according to FIGS. 3 and 4.

The system shown in FIG. 14 is distinct from those described above in requiring but a single control coil Cl even though the system has two O-type main-core components 41, 42, and two by-pass or control cores 43 and 44, each being likewise of generally O-shaped configuration.

As only one control coil is used, it is necessary to apply a thyristor circuit or its equivalent, such as the circuitry illustrated in FIG. 15.

The circuit of FIG. 15 corresponds essentially to that of FIG. 8 described above, except that the amplifier which controls the thyristor 32 is actuated by a signal from a voltage-drop resistor 34 connected across the secondary winding S. The system according to FIG. 15, therefore, regulates itself for a constant voltage which is adjustable by means of a potentiometer 35.

In all of the embodiments so far described, the plane of the main core and its opening extends at a right angle to the plane and opening of the control cores. The embodiments according to FIGS. 16 and 17 are basically different in that the main core and the plane of its loop opening is parallel to, or identical with, the corresponding plane of the control core. This affords further reducing the manufacturing cost while retaining the good controlling or regulating performance of the system, lower the

In the system embodiment shown in FIG. 16, the main core 51 and the control core 53 are wound from a tape of silicon iron, approximately 0.012 inch thick and at a width to suit the wattage required. The core 51 is first wound and then the winding is continued to form the core 53. The winding of core 51 is effected on a mandrel which is left in the core opening until the core 53 is thereafter wound with an added shaping block placed between the completed winding 51 and the winding 53. It will be seen that the two cores, each being generally O-shaped, merge with each other in the lowe portion of the core assembly. Upon completion of the winding operation the coil assembly is bonded with epoxy to form a solid block and is then cut through along the line G—G. This permits the coils Pl, P2, S, Cl and C2 to be assembled with he core as shown in FIG. 16 whereafter the two portions of the core are bonded together.

Generally, the circuitry of the system according to FIG. 16 may correspond to FIG. 15, except that two control coils Cl, C2 are provided.

The embodiment shown in FIG. 17 has the same laminated core assembly 51, 53 and generally the same configuration as that of FIG. 16, except that the cut through the core assembly is a long vertical line as shown at G-G. The same coils are provided but with a different positioning of the primary and secondary windings, and there is only one control C. The circuitry may correspond to that of FIG. 15.

Upon a study of this disclosure it will be apparent to those skilled in the art that my invention permits of various modifications and specific control or regulating uses other than particularly illustrated and described herein, without departing from the essential features of my invention and within the scope of the claims annexed hereto.

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