WO2013067605A2

WO2013067605A2 - New system excitation of classical synchronous generators

Info

Publication number: WO2013067605A2
Application number: PCT/BA2012/000004
Authority: WO
Inventors: Nijaz BANJANOVIĆ; Mirza BANJANOVIĆ
Original assignee: Banjanovic Nijaz; Banjanovic Mirza
Priority date: 2011-11-09
Filing date: 2012-01-31
Publication date: 2013-05-16
Also published as: WO2013067605A3

Abstract

New system excitation of classical synchronous generators includes a rotor and a stator. Rotor (secondary) consists of a shaft (18) with bearings 19 and (20), cylindrical iron core (10,11 and 12) and winding (13). Stator (primary) consists of one or two iron cores ( 17) and (27) with windings ( 16 and 26), distributed around the rotor. Rotor is connected to generator shaft or lies on it (together with its winding). This device looks like a transformer in which the middle column with secondary winding is cut out and stuck on a shaft, together with which it rotates between columns with primary windings. Primary windings are powered from a thyristor excitation regulator. In the rotating secondary winding an AC current is induced, because the magnetic field doesn't change its characteristics when rotating. Endings of the secondary winding (13) are connected to a rectifying part of the classic generator, which powers its excitation coils.

Description

NEW SYSTEM EXCITATION OF CLASSICAL SYNCHRONOUS GENERATORS

1) TECHNICAL FIELD

This invention relates to a new system excitation of classical synchronous generators, according to

International Patent Classification (IPC) classified as: H 02 N - generators and motors, and H 01 F - transformers.

2) TECHNICAL PROBLEM

For years, one of the biggest problems with synchronous machines was powering the electromagnets, i.e. rotor excitation, which was solved with slip rings and brushes, which themselves were a weak spot and a cause of defects 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 axis 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) PRESENTING THE ESSENCE 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.

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.

The new system excitation of classical synchronous machines according to this invention includes a device to transfer electrical energy from the immovable housing of the synchronous machine to a movable shaft, without limitations in power, consisting of a rotor and a stator. That is a transformer in which the middle iron column with the secondary coil is cut out and stuck on a shaft, and the primary columns with their coils are immovable and attached to the housing. The rotor consists of a shaft with bearings, iron core and wire windings around the core. The stator consists of one or two iron cores shaped like a telephone handset with wire windings, distributed on both sides of the rotor (like in classical transformers). The rotor of this device is tightly bound to the generator shaft or the core with the windings is located on the same shaft of the synchronous generator. The ends of the windings are lead over the rotor shaft to the rectifying part of the classical generator, which powers the excitation coils. An AC current for the primary (stator) coils is brought from a simple thynstor excitation regulator, which, in dependence of the output voltage of the generator, increases or decreases AC voltage in the primary coils of the new system excitation of classical synchronous generator. The winding count calculation is the same as for air gap transformers. With this invention, the power is unlimited, and can be as high as needed for normal generator operation, and depends only on the dimensions of the iron cores, copper wire winding count and wire gauge, and what's the most important, even for higher power machines, production costs are low. 5) SHORT DRAWINGS DESCRIPTION

Fig. 1 is a functional block scheme of the new system excitation of synchronous generators.

Fig. 2 is a functional block scheme of the new system excitation of synchronous generators with a scheme of the rotor.

Fig. 3 is a side elevation of all cores of the new generator excitation system with the position of dynamo sheets. Fig. 4 is a side view of the device with marked components.

Fig. 5 is a front view of the device with marked components.

Fig. 6 is a side elevation and explanation for manufacturing of stator cores with positioning of the dynamo sheets.

Fig. 7 is a side elevation of the poles of the rotor core with positioning of the dynamo sheets.

Fig. 8 is a side elevation of the rotor without the windings, with the position of incorporated dynamo sheets.

Fig. 9 is a spatial layout of one stator core with positioning of dynamo sheets.

Fig. 10 is a spatial layout of rotor cores without windings with the positioning of dynamo sheets.

Fig. 1 1 is a side view of the left and right bearing carrier and the stator core with windings.

Fig. 12 is a side view of the shaft with bearings.

Fig. 13 is a side view of the rotor coil core with the positioning of dynamo sheets

Fig. 14 is a spatial layout of the stator spool.

Fig. 15 is a spatial layout of the rotor spool.

Fig. 16 is a spatial layout of one part of the device housing.

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

INVENTION

Relating to the figure 1, one can see that the new system excitation of synchronous machines according to this invention includes iron cores of one or two primary coils (pos. 16 and 26) and an iron core of a secondary coil (pos. 13). The whole system reminds of a transformer, whose middle column (pos. 10,11, and 12) with secondary coil (pos. 13) is cut out and stuck on a shaft, and iron cores (pos. 15 and 27) with primary coils (pos.

16 and 26) are immovable and attached to the housing. When AC current is brought to the primary transformer coils, changing magnetic fluxes of the coils (pos. 16 and 26) are created and they add up in the iron core (pos.

10) which results in voltage induction in the coil (pos. 13), which depends on the number the ratio windings of primary and secondary coils, as well as losses through magnetic resistances of the cores and air gaps. If the secondary part (rotor) is rotated the voltage wont change, although the rotor rotates around its longitudinal shaft.

This way the stator current is transfered from the stator to the rotating rotor, without usage of sparking or heating contacts, and the power that can be transferred is limitless, like in classic transformers. The power losses can be calculated the same way as for classical air gap transformers.

Figure 2 shows a spatial view of the device, depicting its similarity to a transformer. The induced secondary coil voltage is brought over the shaft to the rectifying part to power the excitation coils of classical synchronous generators.

Figure 3 shows a cross-section view of all cores and windings of the device, with positioning of the dynamo sheets done the optimal way to minimize the magnetic resistance.

Figure 4 depicts a side view of the device with its components marked. The rotor consists of the shaft (pos. 8), with bearings (pos. 19 and 20), iron core which is made of two broad iron discs (pos. 11 and 12) and a cylindrical core (pos. 10), secondary windings (pos. 13) which are wound onto the core. The stator part consists of one or two iron cores (pos. 17 and 27) shaped like a telephone handset, with windings (pos. 16 and 26).

These cores are positioned on both sides of the rotor (like the columns in a classical transformer). Ball bearings which bear the shaft and both stator cores are attached to the left (pos. 22) and right carrier (pos. 23), which are made of a non-magnetic material and firmly attached to the device housing (pos. 24), which is also made of a non-magnetic material.

Figure 5 shows a position of all cores and their respective fitting, seen from the front side

Figure 6 shows the look of the stator cores which are made from a long strip of silicon steel, which is wound onto a cuboid spool (and lacquered while wound). After finishing, the whole construct is cut longitudinally and two identical primaries (stator cores) are acquired (Pos. 15 and 27). In cross-section they remind of a telephone handset. Places where they were cut have yet to be finished on a lathe in order to create concave arched surfaces that fit to the convex poles of the rotor as seen in fig. 5, and a spatial view of one such stator core is shown in fig. 9.

Figure 7 depicts two rotor cores (pos. 11 and 12) formed like broad discs made of stacked round stamped dynamo sheets connected together. Beside the cutting for the shaft in the middle of the disc, there is also a conical opening into which the cylindrical rotor core with conical endings (pos. 10) is fitted, as seen in fig. 13. The core (pos. 10) is made from a long strip of silicon steel which is wound onto the shaft, and after its fastening the ends have to be made conical. All core in this invention are made so that the magnetic resistance of the iron cores is minimized, since tehre is already unavoidable resistance at the air gaps.

Figure 8 shows a side elevation of the secondary (rotor), depicting the position of all cores on the shaft and Figure 10 shows the spatial layout of the rotor without the windings.

Figure 12 shows the shaft with ball bearings, which should be made of non-magnetic material to minimize losses due to magnetizing the shaft iron.

Figure 11 shows a cross section of the carrier of the stator core and shaft with bearings (pos. 22 and 23), which are also made of non-magnetic material and firmly attached to the device housing (pos. 24), which consists of two parts, also made of non-magnetic material and their spatial layout can be seen on fig. 16.

Figure 14 depicts a spatial layout of a spool for stator windings and

Figure 15 shows a spatial layout of a spool for rotor windings.

According to this invention, the rotor shaft needs to be on the same line and firmly attached to the shaft of the classical synchronous generator, or the complete rotor with the windings of the secondary (rotor) needs to be adapted to the shaft of the synchronous generator. The endings of the rotor winding (secondary) are lead over the shaft into the rectifying part of classical synchronous generator, which powers the excitation windings. The AC current for the stator windings (primary) is brought from a simple thyristor excitation regulator, which, in dependence of the output voltage of the generator, increases or decreases AC voltage in the primary coils of the new system excitation of classical synchronous generator. The winding count calculation is the same as for air gap transformers. With this invention, the power is unlimited, and can be as high as needed for normal generator operation, and depends only on the dimensions of the iron cores, copper wire winding count and wire gauge, and what's the most important, even for higher power machines, production costs are low.

7) WAYS OF APPLYING THE INVENTION

In that way this invention enables construction of a practical, durable, cheap, reliable and useful new system of excitation in classical synchronous generators and systems of contactless energy transfer for high powers for all rotation based devices and electrical machines with the same problem, which can be easily adapted and economically produced, and which includes significant simplifications and improvements compared to previous classical system of excitations in synchronous machines.

To experts it will be obvious that numerous details in this new system can be changed and adapted, without leaving the scope and essence of this invention.

Applicant:

Nijaz Banjanovic

Claims

1. In synchronous generators the powering of excitation windings was until now realized by using slip rings on a shaft and brushes that slide over them, and that is a weak spot, and cause of defects in synchronous machines. The problem with slip rings was solved with an additional AC current generator on the same shaft with the main generator. The excitation of the additional generator is on the stator, to which an automatically regulated DC voltage is brought, and on the rotor an AC current is induced which is converted to DC current in a rectifying part, and this current is brought to the excitation coils of the main synchronous generator, characterized by, that the new system excitation of classical synchronous generators is an addition on the shaft, which very simply transfers the electric energy from the generator housing to a movable (rotating) shaft without contact, even in a liquid medium, and consists of one or two static windings - the primary - and one dynamic winding - the secondary, which is located on a cylindrical core that rotates together with the shaft, and a device according to this invention reminds of a transformer in which the core with the secondary winding rotates between two cores with primary windings mounted on a carrier of the stator cores and shaft.

2. The new system excitation of classical synchronous generators according to the claim #1, characterized by, have a rotor winding, coiled on a round spool made of isulating material, pulled over the iron core, is simple to coil and has a form of an ordinary solenoid, is immovable and rotates together with the shaft.

3. The new system excitation of classical synchronous generators according to the claims 1 and 2, characterized by, has a rotor core which is tightly pulled over an shaft and firmly attached to it, so that it cannot rotate in relation to the axis,a nd consists of three parts: cylindrical electromagnet core (made from a long strip of silicon steel in order to reduce magnetic resistance, coiled in a cylindrical form, with endings shaped in conical form on a lathe) and two thicker discs of the same thickness (made of multiple round stamped dynamo sheet with an opening for the shaft in the middle and a conical recess for attachment with the cylindrical core).

4. New system excitation of classical synchronous generators according to claim #1, characterized by, has one or more stator coils which are simple to wind, are wound onto insulator spools, mounted on a telephone handset-shaped stator core

5. New system excitation of classical synchronous generators according to claim #1 and #4, characterized by, has one or more stator cores, shaped like a telephone handset, made by winding a long strip of silicon steel onto a couboid form of proper dimensions, while lacquering ensures electrical insulation, and when done the whole form is cut in two symmetrical halves, and at the cutlines the borders are processed into concave areas to fit the convex form of the rotor poles and to minimize the distance to them, in order to reduce air gap magnetic resistance.

6. New system excitation of classical synchronous generators according to claim #1 and #3, characterized by, has a shaft, on which the rotor parts are attached tightly and firmly, so that the shaft suffers smaller centrifugal forces, because the iron core of the rotor is easily balanced, so that the shaft can be made of aluminum, or some other non-magnetic material, in order to minimize losses due to shaft magnetizing, and at the ends of the shaft there are ball bearings which have their respective beds on the carrier of the stator core and shaft.

7. New system excitation of classical synchronous generators according to claim #1 and #6, characterized by, has two carriers for stator cores and shaft with bearings, which are made of a non- magnetic material, and have to bear all forces of attraction and repulsion between the rotor core and stator cores, and with the device housing they make a compact unit.

8. New system excitation of classical synchronous generators according to claim #1 and #7, characterized by, has a two-part housing made of a non-magnetic material onto which two carriers for stator cores and the shaft are attached, as well as terminals and other parts.

9. New system excitation of classical synchronous generators according to claim #1, characterized by that, is constructed similar to a transformer in which the middle core with the secondary coil is cut out and is rotated between other two immovable primary cores, its calculations are made in the same way as for an air gap transformer and according to this invention works normally even when its core with the secondary (or primary) winding rotates with unlimited speed, because the magnetic field doesn't change its characteristics when it rotates.

10. New system excitation of classical synchronous generators according to claim #1, characterized by that, can work in humid or explosive areas, or immersed in a liquid medium, because it has no open unisolated contacts which would cause sparking, and its power is not limited, like in case of transformers, and it can be adapted and used to simplify all kinds of electric machines and devices which need contactless transfer of electrical energy to rotating machine parts from immovable devices for automatic or manual regulation and controlling.

Applicant:

Nijaz Banjanovic