1) TECHNICAL FIELD

This invention is related to synchronous generators without slip rings and brushes, with very simple coils on rotor and stator, which is - according to Intemational Patent Classification (IPC) classified as H 02 N - generators and motors.

2) TECHNICAL PROBLEM

For years, one of the biggest problems with synchronous machines was powering of electromagnets, i.e. rotor excitation, which was solved by slip rings and brushes, which themselves were a weak spot and cause of defects in synchronous machines because of sparking at the contacts, especially on places with high air humidity.

3) BACKGROUND ART

There were many ways to solve the problem of powering the excitation coils of an electromagnet. On the rotor there are iron cores with electromagnet coils, which rotate together with the shaft, thereby creating a rotating magnetic field. In the case of synchronous machines powering the excitation coils is done by means of slip rings on the shaft and brushes which slide over them, being attached to the case of the stator. That is a weak spot and cause of defects in synchronous machines because of sparking at the contacts between the slip rings and brushes, especially on places with high air humidity and when using stronger excitation currents. The problem with the slip rings in synchronous machines is solved by an additional generator of alternating current, mounted on the same shaft as the main generator. The excitation of the additional generator is on the stator, to which an automatically regulated DC current is brought, and on the rotor alternating current is induced. Since the rotor of the additional generator is on the same shaft as the rotor of the main generator, only the acquired voltage is converted to DC current by rectifying part, and brought to the excitation windings of the main generator by conductors. In that way no slip rings and brushes are needed, and the excitation voltage of the main generator is regulated through the excitation voltage of the additional generator.

4) DISCLOSURE OF THE INVENTION

The primary goal of this invention is solving the problem with powering excitation windings of synchronous machines by removing slip rings and brushes, without making the new method more complicated in maintenance.

The secondary goal of this invention is to improve synchronous machines by adding parts not prone to defects. An additional goal of this invention is improving synchronous machines within the machines themselves, without additional elements on the shaft.

Some further goals and advantages of this invention will be shown in the following description, and others will become obvious once this invention starts being applied.

According to this invention, synchronous machines include synchronous generators and motors, which consist of a rotor and a stator. A rotor consists of a shaft with bearings, iron core and windings, which are built around the core, but have no direct contact to it, and which are attached to the case of the machine. A stator consists of six coils mounted on "U"- shaped iron cores, distributed in a circular manner around the stator at an angle to each other. The shaft rotates the iron core, and the windings of both rotor and stator are immovable and attached to the case of machine. The excitation DC voltage can be brought to either rotor windings or stator windings. Since in this invention all coils are immovable and attached to the machine case, only the rotor shaft with the iron core rotates, so that balancing the rotor is much easier. The power of these machines is unlimited and can be chosen as needed, being defined only through the size of iron core, winding count in the coils and the height of the excitation voltage.

5) SHORT DRAWINGS DESCRIPTION

Fig. 1 is a scheme of an electromagnet working while rotating the core inside an immovable spool.

Fig.2 is a side view of a model of a manually operated synchronous generator.

Fig. 3 is a schematic view of core arrangement and powering of windings at the stator and rotor.

Fig. 4 is a schematic view of a monophase generator with excitation on stator windings.

Fig. 5 is a schematic view of a monophase generator with excitation on stator windings rotated by 180°. Fig. 6 is a cross-section of rotor core parts.

Fig. 7 is a cross-section of a three-phase generator with the position of the rotor and stator poles.

Fig. 8 is a cross-section of a three-phase generator with the position of the rotor and stator poles.

6) DETAILED DESCRIPTION OF AT LEAST ONE OF THE WAYS TO REALIZE THE

INVENTION

Following description shows details of this supposed way to realize the invention, whose one possible application possibility is illustrated by accompanying drawings.

Fig. 1 shows a method to generate AC current in the wire windings (pos. 16), which are wound around a transformer sheet core (pos. 15), which is immovable and attached close to the trajectory of pairs of magnetic poles of a rotating electromagnet (pos. 10), which itself hat an immovable spool (pos. 14) with windings (pos. 13), powered by DC current. When during the rotation magnetic poles N and S of the rotating core (pos. 10), begin to align to the endings of the core (pos. 15), it starts being magnetized, and a magnetic flux through it is established. This flux is strong at the beginning, gets weaker as the core gets magnetically saturated, and disappears entirely at the moment of complete side-by-side alignment of the poles. When these poles begin moving away from each other, the iron core gets demagnetized and a magnetic flux of opposite direction is established. This flux is also strong at the beginning and disappears with complete demagnetizing of the iron core. The change of intensity of magnetic flux through the core (pos. 15), caused by action of magnetic field of protruding poles of the rotating iron core (pos. 10) induces AC voltage at the ends of the copper wire winding (pos. 16), wound around the core (pos. 15). The induced AC voltage has a sinusoid shape (one sinusoid) is generated by simultaneous passage of only one pair of protruding magnetic poles by the poles of the stator core and its windings. From the moment when one pair of protruding poles starts aligning with the stator winding core to the moment of their complete alignment, a positive half-period of the current is created. If we stop the rotor at the moment of complete alignment of the cores, no fiirther voltage will be created. When the poles start moving away from each other, the iron core (pos. 15) gets demagnetized and which creates the negative half- period. This proves that in order to induce AC current, after magnetizing the stator iron core by rotor magnetic poles of one polarity it is not necessary to magnetize the stator core with magnetic poles of opposite polarity. Magnetizing the stator core creates one half-period of the AC current, and it's demagnetizing the other, opposite one. When the next couple of protruding magnetic poles of the rotating iron core (pos. 10) passes by the core (pos. 15), the whole cycle is repeated. Fig. 1 reminds of Faraday's demonstration device for creating electric current by magnetic field. Faraday noticed that whenever the switch controlling the powering of the first coil by DC current is turned on, the galvanometer attached to the other coil of the ring-shaped iron core detects an electric current in one direction, and when this switch is turned off, the galvanometer detects a current in the opposite direction. He also noticed that if the mentioned switch remains for a longer time either turned on or off, the galvanometer doesn't show any electric current in the second coil. The same effect is observed in Fig. 1, with the difference that there is no switch to turn the iron core magnetizing current on and off, but due to their rotation, the magnetic poles of the electromagnet get closer to and fiirther from the core with the second coil and so they achieve the same effect. All this indicates similarity between transformers and synchronous generators with static windings without slip rings and brushes. The induced AC voltage in the windings (pos. 16) depends on the rotational speed of the core (pos. 10), strength of the attached DC current in the coil (pos. 13), cross- section area of the core and on the winding count on stator and on rotor, i.e.

Uind = -N A(B S) /At.

The frequency of the induced AC current depends on the number of couples of protruding magnetic poles of the rotating iron core (pos. 10), as well as on the rotational speed of the axis, i.e.

f= n p/60

The magnetic flux flows along the machine parallel to the shaft, and the rotor excitation windings and stator windings are perpendicular to the shaft, and they are wound across the longitudinal core, and that is just the opposite to the contemporary classical electrical machines. A synchronous generator, according to this invention, can be viewed as a transformer with its middle column, which bears the primary coil, cut out and attached to a shaft, so it can be longitudinally rotated between the other (one, two or more) columns with secondary coils. If a DC current (excitation) is brought to this middle column with its primary coil and the shaft bearing it is rotated in all secondary coils mounted on surrounding columns an AC current is induced, with phase shift depending on their position in space related to the core of the rotating column. If a part of the middle column bearing the excitation coils is made in cylindrical form and the wire windings are wound on a tube- shaped spool with inner diameter slightly larger than the core, so that the core can be rotated without direct contact to the spool, by attaching this spool to the case of the machine (which also bears the remaining immovable columns of the transformer, we get a monophase synchronous generator with two couples of protruding poles, without slip rings and brushes, with static coils on both stator and rotor.

Fig.2 shows a side view of a monophase synchronous generator with immovable windings and movable rotor core with 4 pairs of protruding poles. The rotor core is made of iron cylinder with conical endings (pos. 10) over which a tube shaped spool with excitation windings (pos. 13) is pulled over, and iron cores with protruding poles (pos. 11 and 12)which in their middle parts have a conical recess, used attach the cores to the axial part (pos. 10)(Fig. 6). All part of the rotor core are pulled tightly over the shaft (pos. 18), so that the pairs of protruding magnetic poles N and S in line parallel to the axis. The generator housing (pos.24) is made of a nonmagnetic material and bears the rotor excitation windings carrier (pos.21, made of an electrical insulator) and the ball bearing carriers (pos.22 and 23, made of an non-magnetic material), in which ball bearings (pos. 18 and 19) are positioned. These ball bearings hold the shaft (pos. 18). At one end of the shaft there is a hand crank (pos.25), which is used to manually rotate the rotor of the generator. Also attached to the generator housing is a core made of transformer sheets (pos. 15) bearing a spool (pos. 17) with copper wire windings (pos. 16). If a DC voltage is applied to the immovable excitation coil (pos. 13) and by rotating the hand crank (pos.25) the shaft (pos. 18) with rotor cores (pos. 10, 11 , 12) and protruding magnetic poles (which are now magnetized) is rotated, an AC current is induced in the stator coils. Protruding magnetic poles N are radially distributed on one side of the excitation electromagnet, and the protruding magnetic poles S are radially distributed on its other side, so that measured in circumference they take only half of the space they need in classical generators, where over the circumference of the rotor N and S poles are distributed alternately. Because of this factor, the generated current frequency is twice as high as in a classical generator with the same number of protruding poles radially distributed on the rotor.

Fig.3 shows a two-phase generator with 4 pairs of protruding magnetic poles with an immovable coil (pos. 13), to which a DC excitation voltage is brought, and two stator cores (pos. 15 and 27) with coils (pos. 16 and 26). While the poles of the iron core (pos. 15) are located in the space between the protruding magnetic poles of the rotor, the poles of the other core (pos.27) are perfectly aligned with one pair of the rotor magnetic poles. This is the zero position without any voltage in the coils (pos. 16 and 26), because one core (pos. 15) is fully demagnetized and the other one (pos.27) is fully magnetized. If the rotor is turned in the direction indicated by the arrow, the first core (pos. 15) will get magnetized and there will be a magnetic flux through it in one direction, while the other core (pos.27) will be demagnetized, and there will be magnetic flux through it in the direction opposite to the one in the first core (pos. 15). If the windings on both cores are made in the same direction, in both of them an AC current will be induced with a phase shift of 180°, which would make this machine a two-phase generator. In figure 3 the windings are made in opposite directions, so that the induced voltages are synchronized in phase in spite of the opposite direction of magnetic flux through their cores. Since these coils are connected in series, the voltages are additive, so that between the begining of the first coil (pos. 16) and the end of the second coil (pos.26), we get their total altemating voltage. The two cores can be placed at any angle around the rotor. Because of the needed phase shift, only their position related to the protruding rotor poles matters. The angular widths of protruding rotor poles and the angular distance between them, as well as the angular width of the poles of the stator core have to be identical because the shape of the resulting sinusoid depends on this width. If the stator core is wider or narrower than the protruding rotor poles there will be a period of time without voltage between the positive and negative half-periods of the induced voltage. Besides, the stator core coils can be connected serially or parallel, depending on whether we wish to achieve stronger current or higher voltage.

In the case of three-phase generators the poles of stator cores are shifted for a third of the angular pole width each, in order to get a phase shift of 120° between them. Again, the stator poles, the protruding rotor magnetic poles and the space between them must have the same angular width. Maximum number of the stator phase poles depends on the number of the protruding rotor poles, and can be 50% higher than the number of protruding rotor poles. Poles of each phase must be at the same angle related to a protruding rotor pole, and the angular distance between the stator phase poles must be a third of the pole angular width (Fig. 7). The angular width of protruding rotor poles is same as the angular width of spaces between them. If we form groups of three phases with three coils each, three stator cores must have protruding poles with identical free space between them, so that every pole has the same position related to a protruding rotor pole (Fig. 8). These three large cores need to be shifted one third of the pole width from each other. At the bottom of the stator a free zone can be left in order to mount the immovable rotor coil carrier, which however, reduces the number of mountable stator poles.

Fig.4 shows a monophase generator, similar to the one in fig.3, but this time the DC excitation voltage is brought the stator coils (pos. 16 and 26), and in the immovable rotor coil (pos. 13) an AC current is induced. The way of induction of the current is the same as with classical generators: the impacts of the north and south magnetic poles to the iron core with windings change alternately, and this time it is the immovable coil of the rotor. In fig.4 the magnetized core (pos. 15)(electromagnet 15) is positioned between protruding poles of the rotor, so that there is no interaction between them, and the other core (pos.27)(electromagnet 27) is aligned with one pair of protruding rotor poles, so that the rotor core is fully magnetized, and that is the zero position, where no voltage is created in the coil (pos. 13). When the rotor is rotated in the direction indicated by the arrow, its protruding poles move away from the electromagnet (pos.27) and the rotor core gets demagnetized. At the same time one other pair of rotor poles begins aligning itself with the electromagnet (pos. 15), which has opposite polarity compared to electromagnet (pos.27), and which begins magnetizing the rotor core with opposite poles. That facilitates demagnetizing the rotor core and then magnetizes it with the opposite pole, whereby a magnetic flux in one direction is established and a voltage is induced (one half-period). Fig. 5 shows the zero position, where the poles of electromagnet (pos.15) are aligned with one pair of protruding rotor poles, so that the rotor core is magnetized, and the electromagnet poles (pos.27) are positioned in the space between the protruding rotor poles and have no influence to them. If the rotor continues rotating in the direction indicated by the arrow, the protruding rotor poles move away from the electromagnet (pos. 15) and the rotor core gets demagnetized. At the same time one other pair of protruding rotor poles starts getting aligned with the poles of electromagnet (pos.27), which are of opposite polarity compared to the current magnetic polarity of the rotor core, and begin magnetizing the rotor core with this opposite polarity. This facilitates demagnetizing the rotor core and then magnetizes it with opposite polarity, whereby a magnetic flux is established in direction opposite to the previous one, and a voltage of opposite polarity is induced (second half-period). The protruding rotor poles alternately pass by the N and S magnetic poles of the stator electromagnet, whereby the direction of magnetic flux is alternately changed, which results in induction of alternate current in the immovable rotor coil. If we separate the coils (pos. 16 and 26) and bring a DC current only to the coil (pos.16), then the core (pos.15) becomes an electromagnet which induces an AC current in the immovable rotor coil by magnetizing and demagnetizing the rotor core during the passage of its protruding poles by electromagnet (pos. 15). If we bring DC current only to the coil (pos.26), and the coil (pos. 16) is disconnected, then the core (pos.27) becomes an electromagnet which in the immovable rotor coil induces an AC voltage with a phase shift of 180° compared to the previous case, because the protruding rotor poles move past the electromagnet (pos.27) which is of opposite polarity. That means that the alternate current is induced either by one or the other electromagnet of the stator, which can be seen only if the coils are observed separately. When both electromagnets of the stator excitation are powered, the induced voltage is doubled because the sparately induces voltages add up, and at the ends of the immovable rotor coil a resulting voltage can be measured. This is a consequence of intensified

demagnetizing and remagnetizing the rotor core by opposite stator poles.

In any case, it has to be taken into account that because of the eddy currents the rotor cores have to be made out of transformer laminations which are insulated separately. The core (pos. 10) then has to be made from a long strip of silicn steel (for torus transformers) wound on the shaft, and the cores (pos.11 and 12) have to be made of punched tin disks pressed together to achieve the needed thickness, and then finely cut in a lathe to achieve the proper size and shape as demonstrated in fig. 6.

If the excitation coil is - like in this example - mounted on the stator, and the inductive coil on the rotor, it is possible to create a generator with combined excitation. Beside the excitation coils, two horseshoe-shaped permanent magnets with oppositely positioned poles are mounted to the stator (the same way the electromagnet coils are wound in opposite direction so tha the protruding rotor poles alternately move past N and S poles). These permanent magnets are arranged in space so that they overlap with the protruding rotor poles at the same time as the electromagnets of the same polarity so that they reinforce the magnetic flux by adding their own to the one of the electromagnet. In this case the permanent stator magnets always induce a voltage in the static rotor coil of the generator, and the excitation coils on the stator are used to enhance the magnetic flux when the generated voltage starts decreasing due to higher power loads. In that case an electronic excitation regulator rises the voltage on exitation coils, thereby creating an additional magnetic field of the same orientation as that of the permanent magnets, so that these two fields add up in the rotor core, creating a stronger magnetic flux needed to generate the nominal voltage of the generator, which, in this way always remains stable, independently from the power load. Generators with combined excitation save the electrical energy needed to power the generator and reduce the heating of excitation coils, while the automatic generator voltage regulation always functions.

Generators with combined excitation can also be constructed with polarized magnets, when the stator excitation coils are wound on cores made of permanent magnets, so that - when powered - they enhance the magnetic field of the permanent magnet and by that way influence me values of induced voltage.

If we mount three monophase generators (with excitation coils attached to the stator cores and separate rotor cores and belonging rotor coils) on an shaft made of a non-magnetic material, taking precautions that the lines of protruding magnetic poles of the rotor of each generator are shifted two thirds of the angular width of a magnetic pole in relation to each other, in order to induce voltage in the phase coils with phase shift of 120°, we get a three-phase generator resistant to asymmetrical power loads. In that case every single phase has its own independent excitation coil powering at the stator cores, so that it can automatically increase excitation voltage in order to respond to increased power loads only for the phase where this is needed. In that way it can maintain stable voltage over all three phases independently from each other. Besides, in case of a defect, it is easier to just replace the generator for one phase with a spare one than to replace the whole machine altogether, especially when it concerns higher power generators, and because of simpler construction of these machines, replacing faulty excitation coils or phase coils is done much faster.

It is also possible to create three-phase generators with combined excitation on stators with permanent magnets, which would increase generator efficiency and at the same time reduce heating of the excitation coils.

7) WAYS OF APPLYING THE INVENTION

In that way this invention enables construction of practical, durable and usable synchronous machine, which can be produced economically, and which includes significant improvements compared to contemporary classical machines of this type. To experts it will be obvious that numerous details can be changed and adapted, without leaving the scope and essence of this invention.