RU212791U1 - DESIGN OF A SINGLE-PHASE UNIPOLAR GENERATOR - Google Patents

Abstract

The utility model relates to electrical machines and can be used in electrical generators, including wind turbines and generators of autonomous objects. Various types of synchronous generators are known from the prior art, which have common features - this is the presence of excitation poles, as well as the separation of the source of the excitation field (permanent magnet or winding) to the stator and rotor, while in classical electric machines the excitation winding is made in the form of coils located on the teeth of the rotor. The current to the excitation winding in this case is supplied through the brushes to the rings on the rotor and then to the excitation winding. The disadvantage is the need for periodic maintenance, replacement of brushes, reversal of the polarity of the rings, as well as their grinding and beating control. Variants of generators with excitation from permanent magnets do not have brushes, but do not allow you to adjust the excitation flux and the level of its output voltage, which limits the scope. This disadvantage is especially significant when the load is powered directly from the generator, which is sensitive to the voltage level. Variants of a generator with longitudinal excitation are also known, in which the excitation flow is closed longitudinally to the axis of rotation of the rotor. However, their non-magnetic (possibly plastic) casing design is better suited for small to medium power generators. Also known are synchronous generators without brushes and with the ability to control the level of excitation through the use of three machines on one shaft. This is a composite machine consisting of three generators, one of which is based on an inverted electric machine. However, such generators are more difficult to manufacture and maintain. In the proposed solution, there are no brushes and mechanical contact with the overall simplicity of the design. All windings are located on the stator, in the form of coils located on the stator yoke. The design of the generator is simple and easy to implement.

Description

Field of technology to which the utility model belongs

The utility model relates to electrical machines and can be used in electrical generators, including wind turbines and generators of autonomous objects.

State of the art

The prior art unipolar current generator [RF patent for invention No. 2518461], containing a rotating rotor and a fixed stator. As a rotor rotating in a perpendicular magnetic field, a type-setting disk made of metal plates (disk sectors) separated by dielectric spacers with sliding contacts on the disk rotation axis is used. As a fixed stator, the poles of a rotating constant or alternating magnetic field are used, and the number of sectors of the rotor is equal to the number of stator poles or more, and the stator poles of the rotating magnetic field can be created by rotating magnets, or electromagnets, or fixed windings with a magnetic circuit inside, in which a rotating constant or variable field. The number of rotating poles can be 2 or more, subject to the condition that the EMF directions created in the rotor by diametrically located poles are co-directed, and adjacent poles (along the perimeter) create alternating directions of EMF diametrical polarity on the rotor.

The disadvantages of this solution include the presence of a sliding contact apparatus (current collectors), which reduces reliability.

A brushless generator is also known [RF patent for utility model No. 195231], containing a fixed stator with an output winding consisting of coils, a rotor equipped with a cylindrical permanent magnet, sets of poles made of ferromagnetic material installed from its ends and having a through hole in its center each , with dielectric spacers from the inside to isolate the plates of the set of poles from the shaft rotor, the rotor is made composite with a shaft of non-magnetic material in the center, and the stator is made of non-magnetic material and is equipped with slots for magnetic cores, each magnetic core is installed in its corresponding slot longitudinally to the direction of the rotor rotation axis and has two protruding teeth in the stator cavity, corresponding to sets of poles. The number of poles in the set is one more than half of the number of stator magnetic cores, with the number of stator magnetic cores being a multiple of two.

This decision is made by the main prototype, the closest in its technical essence.

The disadvantages of this solution include the presence of a toothed zone of the stator magnetic circuits, which complicates their design, and also makes it impossible to smooth the magnetic flux by manufacturing teeth with extensions.

Disclosure of utility model. Various designs of electrical machines are known from the prior art [1, 2]. Many of them use permanent magnets to produce a magnetic excitation flux, which leads to the appearance of a variable EMF in the generator windings when they are mechanically rotated. Solutions are also possible using excitation windings to obtain magnetic flux - most of them require mechanical contact for their operation, for example, rings on a rotor with brushes. Thus, the use of permanent magnets to obtain a magnetic flux simplifies the design, and makes it possible to eliminate contacts for transmitting current to the field winding - however, it does not allow changing the magnetic field flux. In classical synchronous generators, the excitation winding and the output winding are always located separately on the stator and rotor.

Since the presence of mechanical contact - brushes and rings, can significantly complicate operation (the need for replacement, the likelihood of a sudden failure with the destruction of brushes), the process of finding a solution with the most simple, convenient and efficient design is underway.

At the moment there are only two versions of such a generator without brushes, known from the prior art. The first is the use of a composite electric machine, consisting of two or three generators on a common shaft, one of which is reversed (the stator-rotor windings are reversed). Such generators are used in aviation and often in shipbuilding, where they are installed in emergency power sources. The second is the design of a generator with a longitudinal magnetic flux, proposed earlier by the author of this application. Both of these options have both advantages and disadvantages.

In the proposed solution, there are no brushes and rings on the rotor, with a simple design and the use of a classic generator, without the use of a longitudinal magnetic flux. This is achieved by transferring the excitation poles from the rotor to the stator, and placing them separately from the teeth with the coils of the output winding, i.e. unlike the classical generator, separate coils on the teeth are used.

In FIG. 1 shows the appearance of the 3D model of the original solution, which shows the presence of two (larger) pole coils located opposite each other (diametrically), and two teeth with output winding coils located on them. The figure shows that the rotor is made without coils and has four teeth.

In FIG. 2 shows the device of the proposed solution, where its components are indicated - a ferromagnetic rotor (1), and excitation winding coils (2), output winding coils (3), located on the stator frame, which, according to the theory of electrical machines in [1], forms a common magnetic chain with poles and rotor. The winding coils are doubled to form a symmetrical electrical and magnetic circuit.

Also in FIG. 3 shows the winding diagram of the proposed solution, which is generally the same for the excitation winding and the output winding. It can be seen from the diagram that the coils are divided into pairs, the polarity of switching on in pairs is opposite. Pairs are switched on sequentially and according to each other. This inclusion is explained by the fact that with the same direction of winding of all coils on the magnetic core (frame), which can be mentally represented as the division of a single coil into sections and their distribution around the circumference of the stator frame, the polarity of the magnetic flux in them before and after the poles / teeth will be opposite. Thus, in order to obtain equality of their work, their counter inclusion is required. In pairs of coils between themselves, their inclusion will be consistent, which is explained by the same polarity of the direction of the magnetic flux of the unipolar generator, as shown by the arrows in the poles in Fig. 2.

In FIG. 4 shows the distribution of magnetic field lines during the operation of the proposed solution, where you can see the direction of their distribution from the rotor teeth to the stator teeth, you can also see the path of the magnetic field from the stator poles to its teeth. The proposed solution is also characterized by the equality of the magnetic circuit of the excitation poles and teeth, around which the output winding coils are located. That is, the excitation magnetic flux passes through the same section of the teeth as the poles. This is due to the symmetrical configuration with an equal number of poles and stator teeth, as well as four rotor teeth.

In FIG. 5 shows the output voltage graph obtained on a 3D model in the ANSIS software environment. The voltage has a high degree of sinusoidality, which can be improved by optimizing the geometry and shape of the rotor teeth in a particular technical solution. It can also be noted that the simulation results for the initial configuration in FIG. 1 coincided with the simulation results of the proposed solution, as in FIG. 2, when the number of turns in the excitation windings and the output winding are equal. That is, such solutions are electromagnetically equivalent.

The principle of operation of the proposed solution is based on switching the magnetic field created by the excitation poles on the stator to the teeth with the coils of the output winding. However, the main focus and difference of the proposed solution lies precisely in the design itself, which allows to reduce the height of the poles and teeth by refusing to place winding coils on them, and a significant stator circumference makes it possible to distribute the turns of the mentioned windings along the length, reducing their thickness.

All the features indicated in the distinctive part of the formula are essential for the implementation of the proposed solution, and are not previously known from the prior art in their entirety.

The presented solution is simple and therefore industrially applicable, providing ease of manufacture of components and the assembly process of the generator. Coils are used, which are located on the generator frame, which allows to reduce the height of the poles.

The proposed technical solution is new and has the following fundamental differences from the main prototype:

- the excitation winding and the output winding consist of two pairs of coils each;

- coils in pairs are switched on in series and in opposite directions, and pairs of coils are switched on in series and according to each other, provided that all coils are wound in the same direction;

- the coils are placed on the stator frame, and the coils in pairs are placed on different sides of the corresponding pole or stator tooth;

- the stator contains two poles and two teeth having an equal cross-sectional area, the stator teeth are located opposite each other between the excitation poles, the rotor has four teeth.

Thus, the entire set of essential features of the utility model is previously unknown and leads to a new technical result - brushless voltage generation.

Brief description of the drawings. In FIG. 1 shows the appearance of the original generator. In FIG. 2 shows the device of the proposed solution. Here 1 is the rotor, 2 is the field winding coil, 3 is the output winding coil. In FIG. 3 shows a schematic diagram of the windings of the proposed solution. In FIG. 4 shows the magnetic field lines in cross section of the proposed solution. In FIG. 5 shows the output voltage graph of the proposed solution.

List of used literature.

1. Kopylov I.P. Design of electrical machines. M.: Yurayt Publishing House, 2014.

2. Shtelting G., Beisse A. Electric machines. M.: Publishing house "Energoatomizdat", 2015.

Claims (1)

Unipolar generator containing a fixed stator with excitation poles on it and a rotor made of a ferromagnetic material, said excitation poles have the same magnetic field polarity, characterized in that the excitation winding and the output winding consist of two pairs of coils each, and the coils in the pairs are connected in series and counter, and pairs of coils are connected in series and in accordance with each other, the coils themselves are placed on the stator frame, and the field winding coils of each pair are placed on different sides of the corresponding excitation pole, and the output winding coils of each pair are placed on different sides of the corresponding tooth, the stator contains two poles and two teeth having an equal cross-sectional area, the stator teeth are located opposite each other between the excitation poles, the rotor has four teeth.

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