TECHNICAL FIELD

This invention relates to a method of increasing the efficiency of an electrical generator which generates real power by a change of the reluctance in the magnetic flux path through the generator. In particular, this invention relates to a method of increasing the efficiency of such generators by providing specific components, features and characteristics of the generator in a combination so as to reduce the relative effect of the load on the generator.

BACKGROUND OF THE INVENTION

in the past, electrical generators of the type described herein have been subject to inefficiencies. One of the difficulties was that as the real output power was increased, there was a concomitant increase in the real input power. As the load on the generator increased, there was the concomitant increase in real input power, but the output current was low.

Also, in generators of this type, the inventor has discovered that during operation there is an alternating current superimposed on the excitation current in the excitation coil of the prior art generators. This

alternating current has the effect of reducing current passing through the load, which has the tendency of reducing the efficiency of the generator.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to at least partially overcome the disadvantages of the prior art. Also, it is an object of this invention to provide an alternative type of electrical generator in which the relative effect of the load is reduced. And, it is a further object of this invention to reduce the effect of the alternating current that is superimposed on the excitation current of such generators.

Accordingly, in one of its broad aspects, this invention resides in providing a method of increasing the efficiency of an electrical generator for use in association with a generator which generates real output power by a change of the reluctance of the magnetic flux path; the method comprising: providing the following components, features and characteristics of the generator: (a) number of turns [Nl] of excitation coils of an excitation circuit around the magnetic flux path;

(b) number of turns [N2] of load coils around the magnetic flux path;

(c) number of poles [p] of the reluctance-changing part; (d) revolutions per minute [n] of the reluctance-changing

part ;

(e) average reluctance [Ra] of the magnetic flux path; and

(f) amplitude of change [Re] of the reluctance of the magnet flux path: in a combination so as to reduce the relative effect of a load [RL ohms] in the load coil in the following relationship:

(N1/N2) x lex Re ι_ + ______

Ra N2 ² w

where w = 27lnp = 2 ^" 7ff, where f = _n£

60 60

Further aspects of the invention reside in providing methods and means for reducing the effect of the alternating current which is superimposed on the excitation coil.

Further aspects of the invention reside in providing an electrical generator without a rotor or other moving part of the magnetic flux path of the generator by which the reluctance is changed.

Further aspects of the invention will become apparent upon reading the following detailed description and the drawings which illustrate the invention and preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 is a schematic, perspective view of a preferred embodiment of the invention; Figure 2 is a preferred embodiment of a reducing circuit of the invention;

Figure 3 is a schematic drawing of a preferred embodiment of the logic and thyristor circuits of a reducing circuit of the invention; Figure 4 is a schematic, perspective view of two generators of the invention having common stator and rotor;

Figure 5 is a schematic, perspective view of two generators of the invention constructed substantially identically;

Figure 6 is a schematic, perspective view of a further embodiment of the invention;

Figure 7 is a schematic, perspective view of a further embodiment of the invention; Figure 8 is a schematic, perspective view of a further embodiment of the invention.

Figure 9 is a schematic, perspective view of a further embodiment of the invention;

Figure 10 is a schematic, perspective view of a further embodiment of the invention;

Figure 11 is a schematic, perspective view of a further embodiment of the invention;

Figure 12A is a cross-sectional view of a further embodiment of the invention; and

Figure 12B is a cross-sectional view of a further embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

OF THE INVENTION

Shown in Figure 1 is a simplified generator 10 of the type that generates real output power Por by change of the reluctance R in a magnetic flux path 12. The generator 10 as shown has a stator 14 and a rotor 16 which form the magnetic flux path 12. Rotor 16 is rotated by shaft 18. Shaft 18 is driven by input power Pi. Shaft 18 and, therefore, rotor 16 rotate at a rate of "n" revolutions per minute. When rotor 16 is in position 16A as shown in

Figure 1, the reluctance R of the magnetic flux path 12 is maximum. When the rotor 16 is in position 16B as shown by dashed lines in Figure 1, the reluctance R is a minimum.

The average reluctance "Ra" of the magnetic flux path 12 can be determined with respect to time. Also, the amplitude of

change "Re" of the reluctance R of the magnetic flux path 12 can be determined with respect to time. In this embodiment, the reluctance-changing part is the rotor 16.

As shown in Figure 1, the number of poles "p" of rotor 16 is two poles, pi and p2. However, it is possible for the rotor 16 to have a greater number of poles as is practical. In practical generators, the number of poles p would usually be in the range of about 2 to 36.

Excitation circuit 20 has an excitation source 22 which is a d.c. or a.c. source. The excitation source 22 supplies excitation current lex through excitation coils 24, which are coiled around the magnetic flux path 12. The number of excitation coils 24 is "Nl". As shown for simplicity in Figure 1, Nl is three. However, in practical generators, Nl would usually be in the range of about 3 to several thousands, say to about 50,000.

Also shown in Figure 1 a load circuit 26. Load circuit 26 has a load "RL" which is connected to load coils 28 which are coiled around the magnetic flux path 12. The number of load coils 28 is "N2". As shown for simplicity in Figure 1, N2 is five. However, in practical generators, N2 would usually be in the range of about 3 to several thousands, say to about 45,000.

It has been discovered, recognized and determined by the present inventor that the base harmonic of the effective current Ieff passing through the load circuit 26, and thus the load RL, is proportional to the following relationship (where the symbols have the meanings as given above) :

(N1/N2) x lex Re

1 + JRL Ra N2 ² w

where w = 21L np

60

Equation 1

By recognizing that the real output power Por of the generator 10 is defined by the following relationship:

Por = (Ieff)^ x RL

Equation 2

the present inventor has recognized that the effect of the load RL on the real input power requirement can be reduced by reducing the relative effect of the load RL in Equation 1 above.

The relative effect of the load RL in Equation 1 can be reduced by providing the generator 10 with a combination of components, features and characteristics C so as to increase the value of Equation 1 for a given load RL, or even an increased load RL, without decreasing the load RL itself. Particularly, this task is accomplished by providing the following components, features and characteristics (referred to collectively as components C) of the generator 10 in a combination so as to reduce the relative effect of the load RL in the relationship as

defined by Equation 1.

In a preferred embodiment of the invention, the components C are provided such that the value of:

RL N2 ² w Equation 3

approaches zero by increasing the product N2 ^A w by increasing the number of turns N2 of the load coils 28 and/or w, or both, and the ratio of N1/N2 does decrease substantially.

In a further preferred embodiment of the invention, the ratio N1/N2 increases substantially when the number of turns N2 of the load coils 28 is increased by further increasing the number of turns Nl of the excitation coils 24.

The present inventor has also discovered, recognized and determined that during operation of the generators of the type as described herein, there is an alternating current Is which is superimposed on the excitation current lex in the excitation coils 24 of excitation circuit 20. This superimposed current Is has an effect of reducing the effective current leff passing through the load coils 28 and the load RL. Thus, having discovered, recognized and determined the existence of this deleterious superimposed current Is, it is recognized that the effect of the superimposed current Is should be reduced. in a preferred embodiment of the invention, the effect of the superimposed current Is is reduced by inserting in the excitation circuit 20 a reducing circuit 30

as shown generally in Figure 1. Preferably, as shown in Figure 2, the reducing circuit 30 comprises a comparator means 32 for comparing the varying amplitude lex-amp of the excitation current lex to an amplitude Idc-amp of a d.c. current Idc. The reducing circuit 30 also comprises a reduction means 34 for reducing the difference D between the varying amplitude lex-amp of the excitation current lex and the amplitude Idc-amp of the d.c. current Idc.

Preferably, the comparator means 32 and the reducing means 34 are comprised of logic and thyristor circuits which could be designed, constructed and implemented by those skilled in the art of electronic circuitry. An example of such circuits is shown in

Figure 3.

In another preferred embodiment for reducing the effect of the superimposed current Is, the effect of the superimposed current Is is reduced by providing a common d.c. supply 50 to excite the first generator 10 and to excite a second generator 100. The second generator 100 may be constructed together with the first generator 10, and having a common rotor 16, as shown in Figure 4, or a common stator (not shown). Alternatively, the second generator 100' may be constructed separately from the first generator 10 and substantially identical to the first generator 10, as shown in Figure 5.

Although the invention has been described thus far with respect to a specific form of generator which generates electrical power by periodically changing the reluctance of the magnetic flux path of the generator, the invention is

applicable to other specific forms of such generators. One such generator is shown in Figure 6 as generator 40. In this embodiment, the generator 40 is substantially the same as generator 10 as described above, except that instead of the rotor as the reluctance-changing part, generator 40 has a moving part 42 through which the magnetic flux path 12 passes as the reluctance-changing part.

The magnetic reluctance R can be changed periodically by moving the part 42 of the magnetic flux path 12 in a generally in and out direction as indicated generally as A, or in a generally to and fro direction as indicated generally as B.

In this embodiment, the "number of poles "p" of the reluctance-changing part" should be considered to be 2, and the "revolutions per minute "n" of the reluctance- changing part" should be considered to be one half the number of times per minute that the reluctance R periodically changes as a result of the movement of the part 42. In another form of generator 50, as shown in

Figure 7, there is a plurality of parts 52 which are mounted on a rotating body 54 (partially shown) such that the parts 52 are rotated past the ends 56A and 56B of the stationary part 58 of the magnetic flux path 12 of the generator 50 so as to periodically change the reluctance R of the magnetic flux path 12. In this embodiment, the reluctance-changing part is the part 52 and, therefore, the "number of poles "p" on the reluctance-changing part" should be considered to be the number of parts 52 mounted on the rotating body 54, and

- li ¬ the "revolutions per minute "n" of the reluctance-changing part" should be considered to be the revolutions per minute of the rotating body 54.

In yet another embodiment of the invention, the reluctance of the magnetic flux path is changed without the necessity of rotating a rotor or spatially moving a part of the magnetic flux path. The change in reluctance is obtained by magnetically saturating or nearly saturating a portion of the magnetic flux path of the generator. in this form of generator, as shown in Figure 8, generator 60 has a first or primary magnetic flux path 12, a stator portion 14, excitation circuit 20 with excitation source 22 and load circuit 26 all as described above with respect to generator 10. However, instead of having rotor 16 or moving parts 42 or 52, generator 60 has a common region 62 and a secondary magnetic flux path 64 which passes through the common region 62. The first or primary magnetic flux path 12 also passes through the common region 62. The secondary magnetic flux path 64 may also be referred to as the efficiency-improving magnetic flux path 64.

The excitation circuit 20 includes the excitation current lex which may also be referred to as the primary current Ip. The primary current induces the primary magnetic flux Fp which follows the primary magnetic flux path 12.

The efficiency-improving magnetic flux path 64 is positioned and configured with respect to the first magnetic flux path 12 such that there is a first region 12' of the first magnetic flux path 12 that extends between the first

portion 12A of the first magnetic path 12 and the second portion 12B of the first magnetic path 12 not in the common region 62 but in the stator portion 14. There is also a second region 12' ' of the first magnetic flux path 12 that extends between the first portion 12A of the first magnetic flux path 12 and the second portion 12B of the first magnetic flux path 12 that is in the common region 62.

The second region 12' * is the common region 62. This region is common to both the first magnetic flux path 12 and the efficiency-improving magnetic flux path 64.

The efficiency-improving magnetic flux path 64 has a magnetic reluctance MR2, and a first end portion 64A and a second end portion 64B. The first end portion 64A is magnetically connected, preferably through an optional gap 66A, to a first portion 12A of the first magnetic path 12 and the second end portion 64B is magnetically connected, preferably through an optional gap 66B, to a second portion 12B of the first magnetic path 12. In this embodiment, the portions 12A and 12B are located on the the common region 62.

The first region 12' has a magnetic reluctance MR' and the second region 12* ^• has a magnetic reluctance MR' ' . The magnetic reluctance MR ¹ ' of the common region 62 is greater when saturated, and preferably much greater, than the magnetic reluctance MR ¹ of the first region 12'. This can be readily accomplished by having the common region 62 periodically saturated by means 70.

The means 70 includes an electric conductor loop

72 with at least one loop 72A around the efficiency- improving magnetic flux path 64. When tertiary electric current It, which is preferably reactive current or substantially reactive current with a frequency "f", is caused to flow in the conductor loop 72, for example by reason of a suitable power source 74, a tertiary varying magnetic flux Ft with a frequency of "f" can be induced which will periodically saturate the common region 62. Preferably, the frequency "f" will be within the range of about 5 Hertz to about 1000 MegaHertz. However, the particular frequency selected will depend on the particular application.

The appropriate selection of tertiary current It will result in the magnitude and direction of tertiary flux Ft being substantially in the same direction as the primary flux Fp in the common region 62.

Also included within the invention is means for substantially preventing the primary magnetic flux Fp from flowing in the efficiency-improving magnetic flux path 64 that is not in the common region 62. In one embodiment of the invention, this means comprises the magnetic reluctance MR2 of the efficiency-improving magnetic flux path 64 outside the common region 62 being substantially greater than the magnetic reluctance MR ¹¹ of the common region 62. In another embodiment of the invention, the means for substantially preventing the primary magnetic flux Fp from flowing in the efficiency-improving magnetic flux path 64 outside the common region 62 comprises the magnitude of the tertiary magnetic flux Ft being substantially greater

than the magnitude of the primary magnetic flux Fp.

In another embodiment of the invention, both end portions 64A, 64B of the efficiency-improving magnetic flux path 64 are directly connected magnetically to the first magnetic flux path 12 by physically connecting the relevant end portions 64A, 64B to the relevant first and second portions 12A, 12B of the first magnetic flux path. This embodiment is shown in Figure 9.

In another embodiment of the invention, only one end portion 64A, 64B of the efficiency-improving magnetic flux path 64 is spatially separated from the first magnetic flux path 12 by a gap 66A or 66B.

The gap 66A or 66B may be an air gap or a gap made from a material having a magnetic reluctance greater than the magnetic reluctance MR2 of the efficiency-improving magnetic flux path 64 outside the common region 62 or the magnetic reluctance MR' ' of the common region 62.

Preferably, the common region 62 is spatially separated from the efficiency-improving magnetic flux path 64 outside the common region 62 and from the first portion 12' of the first magnetic flux path 12 as shown in Figure 8. Preferably, the common region 62 is spatially separated from the first portion 12* of the first magnetic flux path 12 by gaps 68A and 68B which may be air gaps or gaps of other suitable material.

Also, it is possible to have the common region 62 physically connected to the first region 12' either at one of the regions 12A or 12B, or at both of the 12A and 12B locations, as shown in Figure 10.

In these embodiments where the change in

reluctance is developed by magnetic saturation, the reluctance-changing part is that part of the generator that causes the change in the reluctance and, therefore, product "np" which has previously been defined as the "number of poles "p ⁿ on the reluctance-changing part" multiplied by the "revolutions per minute "n" of the reluctance-changing part" should be considered to be the frequency "f" as described above multiplied by 60, or np = f x 60 Therefore, "n" should be considered to be f divided by p and multiplied by 60, and "p" should be considered to be f divided by n and multiplied by 60, such that

n = f x 60

and f x 60 n in other embodiments of the invention, the excitation circuit is replaced by a permanent magnet. The permanent magnet will produce the primary magnetic flux. Therefore, the product Nl x lex in Equation 1 is replaced by the appropriate equivalent for the particular arrangement of permanent magnets. It will be understood by those skilled in the appropriate arts as to what the appropriate equivalent ought to be.

In a further embodiment of the invention, as shown in Figure 11, there is a secondary magnetic flux or efficiency-improving magnetic flux Ftp similar to the flux Ft shown in Figures 8, 9 and 10. However, secondary flux Ftp is substantially perpendicular to primary flux Fp at the

portion 62 of the secondary magnetic flux path 64p that is common with the first magnetic flux path 12. Also, secondary flux Ftp need not be at 90° to the primary flux Fp in order to operate. It is possible that the secondary flux Ftp be at some other angle to the primary flux Fp in the region 62 where the secondary magnetic flux path 64p and the first magnetic flux path 12 are common.

In order to further improve the efficiency of the invention, the size of the common region 62 (as shown in Figure 11) can be increased in order to increase the amount of saturation. The size of the common region 62 can be increased by changing the geometry of the device to that shown generally in Figures 12A and 12B. Figures 12A and 12B show a hollow, generally-toroidally-shaped body 80. Figure 12A is a cross-sectional view of the body 80 along the line 12A-12A. Figure 12B is a cross-sectional view of the body 80 along the line 12B-12B.

Although the body 80 is shown to be generally circular in both of its cross-sections, the body 80 could have any other form of polygonal cross-sections, including trapazoidal (preferably rectangular or square), pentagonal, hexagonal, octagonal and decagonal. Also, the cross- sectional shapes as viewed along line 12A-12A need not be the same as the cross-sectional shape when viewed along line 12B-12B.

Excitation circuit 20 with excitation source 22 enters into body 80 through opening 82 and loops through the interior 84 of the body 80. Although only one loop of excitation circuit 20 is shown inside the body 80, there

would usually be many loops. Excitation circuit includes excitation current lex which may also be referred to as the primary current Ip. When the primary current Ip flows in the excitation circuit 20, a primary magnetic flux Fp flows in the body 80 as shown.

A load circuit 26 is connected to load RL. The load circuit loops through the interior 84 of the body 80. Although only one loop of the load circuit 26 is shown, there are usually many loops.

A saturating excitation circuit 70 has a source 74. Saturating circuit 70 is wound substantially perpendicularly to the excitation current Ip. Preferably, the saturating coils 70 are wound around the exterior of the body 80 as shown. Current It is caused to flow in the saturating circuit 70 which, in turn, causes a saturating flux Ftp in the body 80. Saturating flux Ftp is substantially perpendicular to primary flux Fp.

Thus, as described above with respect to Figures 8 to 11, the saturation circuit 70 causes periodic magnetic saturation in the body 80. However, in the present embodiment, the common portion 62 is the entire body 80.

It will be understood that, although various features of the invention have been described with respect to one or another of the embodiments of the invention, the various features and embodiments of the invention may be combined or used in conjunction with other features and embodiments of the invention as described and illustrated herein.

Although this disclosure has described and

illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to these particular embodiments. Rather, the invention includes all embodiments which are functional, electrical, magnetic or mechanical equivalents of the specific embodiments and features that have been described and illustrated herein.