Synchronous generators with permanent magnets. Permanent magnet synchronous generators Permanent magnet synchronous generators

The field of activity (technology) to which the described invention belongs

The know-how of the development, namely, this invention of the author relates to the field of electrical engineering, in particular to synchronous generators with excitation from permanent magnets, and can be used in autonomous power sources on cars, boats, as well as in autonomous power supplies for consumers with alternating current as a standard industrial frequency, and increased frequency and in autonomous power plants as a source welding current for electric arc welding in the field.

DETAILED DESCRIPTION OF THE INVENTION

Known synchronous generator with excitation from permanent magnets, containing a stator carrier assembly with support bearings, on which an annular magnetic circuit is mounted with pole protrusions along the periphery, equipped with electric coils placed on them with an armature stator winding, and also mounted on a support shaft for rotation in the mentioned excitation support bearings (see, for example, A.I. Voldek, "Electric Machines", ed. Energia, Leningrad branch, 1974, p. 794).

The disadvantages of the known synchronous generator are significant metal consumption and large dimensions due to significant metal consumption and dimensions of the massive cylindrical shape a rotor made with permanent excitation magnets made of hard magnetic alloys (such as alni, alnico, magnico, etc.).

Also known is a synchronous generator with excitation from permanent magnets, containing a stator bearing assembly with support bearings, on which an annular magnetic circuit is mounted with pole protrusions along the periphery, equipped with electric coils placed on them with an armature stator winding, mounted with the possibility of rotation around the annular magnetic circuit of the stator with a mounted on the inner side wall with an annular magnetic insert with magnetic poles alternating in the circumferential direction, covering the pole ledges with electric coils of the armature winding of the specified annular stator magnetic circuit (see, for example, RF patent No. 2141716, class H 02 K 21/12 according to application No. 4831043/09 dated March 2, 1988).

A disadvantage of the known synchronous generator with excitation from permanent magnets is the narrow operating parameters due to the lack of the ability to control the active power of the synchronous generator, since in the design of this synchronous inductor generator there is no possibility of quickly changing the value of the total magnetic flux created by individual permanent magnets of the specified annular magnetic insert.

The closest analogue (prototype) is a synchronous generator with excitation from permanent magnets, containing a stator bearing assembly with support bearings, on which an annular magnetic circuit is mounted with pole ledges along the periphery, equipped with electric coils placed on them with a multi-phase armature winding of the stator, mounted on a support shaft with the possibility of rotation in the mentioned support bearings around the annular stator magnetic circuit; RF No. 2069441, class H 02 K 21/22 according to application No. 4894702/07 of 06/01/1990).

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The disadvantage of the known synchronous generator with excitation from permanent magnets is also narrow operating parameters, due to both the inability to control the active power of the synchronous inductor generator, and the inability to control the magnitude of the output AC voltage, which makes it difficult to use it as a source of welding current in arc welding (in the design of the well-known synchronous generator, there is no possibility of quickly changing the magnitude of the total magnetic flux of individual permanent magnets, which form an annular magnetic insert between themselves).

The purpose of the present invention is to expand the operational parameters of a synchronous generator by providing the possibility of regulating both its active power and the possibility of regulating the AC voltage, as well as providing the possibility of using it as a source of welding current when conducting electric arc welding in various modes.

This goal is achieved by the fact that a synchronous generator with excitation from permanent magnets, containing a stator bearing assembly with support bearings, on which an annular magnetic circuit is mounted with pole protrusions along the periphery, equipped with electric coils placed on them with a multi-phase armature winding of the stator, mounted on a support shaft with the possibility of rotation in the mentioned support bearings around the stator annular magnetic circuit; the stator is made of a group of identical modules with the specified annular magnetic circuit and an annular rotor, mounted on one support shaft with the possibility of their rotation relative to each other around an axis coaxial with the support shaft, and they are connected by a drive kinematically connected with them to rotate them relative to each other, and the same phases of the armature windings in the modules of the stator bearing unit are interconnected, forming the common phases of the stator armature winding.

An additional difference of the proposed synchronous generator with excitation from permanent magnets is that the same magnetic poles of the annular magnetic inserts of the annular rotors in adjacent modules of the stator carrier assembly are located congruently to each other in the same radial planes, and the phase ends of the armature winding in one module of the stator carrier assembly are connected to the beginnings of the armature winding phases of the same name in another adjacent module of the stator carrier unit, forming in connection with each other the common phases of the stator armature winding.

In addition, each of the modules of the stator bearing assembly includes an annular sleeve with an outer thrust flange and a sleeve with a central hole in the end, and the annular rotor in each of the modules of the stator carrier assembly includes an annular shell with an internal thrust flange, in which the said corresponding annular magnetic insert is installed. , wherein said annular bushings of the modules of the stator bearing assembly are connected by their inner cylindrical side wall with one of the said support bearings, the other of which are connected with the walls of the central holes in the ends of the indicated corresponding cups, the annular shells of the annular rotor are rigidly connected to the support shaft by means of fastening units, and the annular magnetic circuit in the corresponding module of the stator bearing assembly is mounted on the specified annular bushing, rigidly fastened with its outer thrust flange to the side cylindrical wall of the cup and forming, together with the latter, an annular cavity in which the pointer is placed the corresponding annular magnetic circuit with electric coils of the corresponding stator armature winding. An additional difference of the proposed synchronous generator with excitation from permanent magnets is that each of the fastening units connecting the annular shell of the annular rotor with the support shaft includes a hub mounted on the support shaft with a flange rigidly fastened to the internal thrust flange of the corresponding annular shell.

An additional difference of the proposed synchronous generator with excitation from permanent magnets is that the drive for the angular rotation of the modules of the stator carrier assembly relative to each other is mounted by means of a support assembly on the modules of the stator carrier assembly.

In addition, the drive for angular rotation relative to each other of the modules of the stator bearing assembly is made in the form of a screw mechanism with a lead screw and a nut, and the supporting assembly for the angular turning drive of the sections of the stator carrier assembly includes a support lug fixed on one of the mentioned cups, and a support bar on the other cup. , while the lead screw is pivotally connected by a two-degree hinge at one end through an axis parallel to the axis of the mentioned support shaft, with the specified support bar, made with a guide slot located along the arc of the circle, and the nut of the screw mechanism is pivotally connected at one end with the said lug, is made at the other end with a shank passed through a guide slot in the support bar and equipped with a locking element.

The essence of the invention is illustrated by drawings.

Figure 1 shows a General view of the proposed synchronous generator with excitation from permanent magnets in a longitudinal section;

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Figure 2 - Synchronous generator with excitation from permanent magnets, view A;

Figure 3 shows schematically the magnetic excitation circuit of a synchronous generator in the embodiment with three-phase electric circuits of the stator armature windings in the initial initial position (without angular displacement of the corresponding phases of the same name in the modules of the stator carrier unit) for the number of pairs of stator poles p=8;

Figure 4 - the same, with the phases of the three-phase electrical circuits of the anchor windings of the stator, deployed relative to each other in the angular position at an angle equal to 360/2p degrees;

Figure 5 shows the option electrical circuit connections of the anchor windings of the stator of the synchronous generator with the connection of the phases of the generator with a star and the series connection of the same phases in the common phases formed by them;

Figure 6 shows another version of the electrical circuit for connecting the armature windings of the stator of a synchronous generator with the connection of the phases of the generator in a triangle and the series connection of the same phases in the common phases formed by them;

a schematic vector diagram of the change in the magnitude of the phase voltages of a synchronous generator with an angular turn of the corresponding phases of the same name of the stator armature windings (respectively, the modules of the stator carrier unit) by the corresponding angle and when the indicated phases are connected according to the "star" scheme

Figure 7 shows a schematic vector diagram of the change in the magnitude of the phase voltages of a synchronous generator with an angular turn of the corresponding phases of the same name of the stator armature windings (respectively, the modules of the stator carrier unit) at the appropriate angle and when these phases are connected according to the "star" scheme;

the same, when connecting the phases of the stator armature windings according to the "triangle" scheme

Figure 8 - the same, when connecting the phases of the anchor windings of the stator according to the "triangle" scheme;

diagram with a graph of the dependence of the output linear voltage of a synchronous generator on the geometric angle of rotation of the same phases of the stator armature windings with the reduction of the corresponding electric angle of rotation of the voltage vector in the phase for connecting the phases according to the "star" scheme

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Figure 9 shows a diagram with a graph of the dependence of the output linear voltage of a synchronous generator on the geometric angle of rotation of the same phases of the armature windings of the stator with the reduction of the corresponding electrical angle of rotation of the voltage vector in the phase for connecting the phases according to the "star" scheme;

diagram with a graph of the dependence of the output linear voltage of a synchronous generator on the geometric angle of rotation of the same phases of the stator armature windings with the reduction of the corresponding electrical angle of rotation of the voltage vector in the phase for connecting the phases according to the "triangle" scheme

Figure 10 shows a diagram with a graph of the dependence of the output linear voltage of a synchronous generator on the geometric angle of rotation of the same phases of the armature windings of the stator with the reduction of the corresponding electrical angle of rotation of the voltage vector in the phase for connecting the phases according to the "triangle" scheme.

The synchronous generator with excitation from permanent magnets contains a stator bearing assembly with support bearings 1, 2, 3, 4, on which a group of identical annular magnetic cores 5 is mounted (for example, in the form of monolithic disks made of powder composite magnetically soft material) with pole protrusions along the periphery, equipped with electric coils 6 placed on them with multi-phase (for example, three-phase, and generally m-phase) armature windings 7, 8 of the stator, mounted on the support shaft 9 with the possibility of rotation in the mentioned support bearings 1, 2, 3, 4 around the bearing assembly stator, a group of identical annular rotors 10, with annular magnetic inserts 11 mounted on the inner side walls (for example, in the form of monolithic magnetic rings made of powder magnetoanisotropic material) with magnetic poles alternating in the circumferential direction from p-pairs (in this version of the generator, the number of pairs p magnetic poles is 8), covering the pole protrusions with electric coils 6 armature windings 7, 8 of the said annular magnetic circuits 5 of the stator. The stator bearing assembly is made of a group of identical modules, each of which includes an annular bushing 12 with an outer thrust flange 13 and a cup 14 with a central hole "a" in the end 15 and with a side cylindrical wall 16. Each of the annular rotors 10 includes an annular shell 17 with internal thrust flange 18. The annular bushings 12 of the modules of the stator bearing assembly are associated with their inner cylindrical side wall with one of the mentioned support bearings (with support bearings 1, 3), the other of which (2, 4) are associated with the walls of the central holes "a" in the ends 15 of the specified corresponding glasses 14. The annular shells 17 of the annular rotors 10 are rigidly connected to the support shaft 9 by means of fasteners, and each of the annular magnetic cores 5 in the corresponding module of the stator bearing assembly is mounted on the specified annular sleeve 12, rigidly fastened with its outer thrust flange 13 with side cylindrical wall 16 of the cup 14 and forming together with the last a single annular cavity "b" in which the specified corresponding annular magnetic circuit 5 with electric coils 6 of the corresponding armature winding (armature windings 7, 8) of the stator is placed. The modules of the bearing assembly of the stator (annular bushings 12 with sleeves 14 that form these modules) are installed with the possibility of their rotation relative to each other around an axis coaxial with the support shaft 9, and are equipped with a kinematically connected drive for angular rotation of them relative to each other, mounted by means of the support assembly on the modules of the stator bearing assembly. Each of the fasteners connecting the annular shell 17 of the corresponding annular rotor 10 with the support shaft 9 includes a hub 19 mounted on the support shaft 9 with a flange 20 rigidly fastened to the internal thrust flange 18 of the corresponding annular shell 17. The drive for the angular rotation of the stator bearing assembly modules is different relative to each other in the presented private embodiment is made in the form of a screw mechanism with a lead screw 21 and a nut 22, and the support unit of the drive for the angular turn of the sections of the bearing assembly of the stator includes a support lug 23 fixed on one of the mentioned cups 14, and on the other cup 14 a support bar 24 The lead screw 21 is pivotally connected by a two-degree hinge (a hinge with two degrees of freedom) with one end "c" by means of an axis 25 parallel to the axis O-O1 of the mentioned support shaft 9, with the specified support bar 24, made with a guide slot "g" located along the arc of a circle ", and the nut 22 of the screw mechanism is pivotally connected by one the end with the aforementioned support lug 23, is made at the other end with a shank 26 passed through the guide slot "g" in the support bar 24, and is equipped with a locking element 27 (lock nut). At the end of the nut 22, pivotally connected with the support lug 23, there is an additional locking element 28 (additional locking nut). The support shaft 9 is equipped with fans 29 and 30 for cooling the armature windings 7, 8 of the stator, one of which (29) is located at one end of the support shaft 9, and the other (30) is placed between the sections of the stator bearing assembly and mounted on the support shaft 9. bushings 12 of the sections of the stator bearing assembly are made with ventilation holes "d" on the outer thrust flanges 13 for passing the air flow into the corresponding annular cavities "b" formed by the annular bushings 12 and cups 14, and thereby cooling the anchor windings 7 and 8, placed in electric coils 6 on the pole protrusions of the annular magnetic cores 5. At the end of the support shaft 9, on which the fan 29 is located, a pulley 31 is mounted V-belt transmission to drive the annular rotors 10 of the synchronous generator. The fan 29 is fixed directly on the V-belt pulley 31. At the other end of the lead screw 21 of the screw mechanism, a handle 32 is installed for manual control of the screw mechanism of the drive for the angular rotation of the modules of the stator bearing assembly relative to each other. The phases of the same name (A1, B1, C1 and A2, B2, C2) of the armature windings in the ring magnetic circuits 5 modules of the stator carrier unit are interconnected, forming common phases of the generator (connection of the same phases in general view both serial and parallel, as well as compound). The magnetic poles of the same name ("north" and, accordingly, "south") of the annular magnetic inserts 11 of the annular rotors 10 in adjacent modules of the stator bearing assembly are located congruently to each other in the same radial planes. In the presented embodiment, the ends of the phases (A1, B1, C1) of the armature winding (winding 7) in the annular magnetic circuit 5 of one module of the stator carrier unit are connected to the beginnings of the same phases (A2, B2, C2) of the armature winding (winding 8) in an adjacent other module bearing node of the stator, forming in series connection between them the common phases of the stator armature winding.

Synchronous generator with excitation from permanent magnets works as follows.

From the drive (for example, from an internal combustion engine, mainly diesel, not shown in the drawing) through the pulley 31 of the V-belt transmission, the rotational movement is transmitted to the support shaft 9 with annular rotors 10. When the annular rotors 10 (annular shells 17) rotate with annular magnetic inserts 11 (for example, monolithic magnetic rings made of powder magnetoanisotropic material) rotating magnetic fluxes are created that penetrate the air annular gap between the annular magnetic inserts 11 and the annular magnetic cores 5 (for example, monolithic disks made of powder composite magnetically soft material) of the modules of the stator bearing assembly, as well as penetrating the radial pole protrusions (conventionally not shown in the drawing) of the annular magnetic circuits 5. During the rotation of the annular rotors 10, the alternating passage of the "north" and "south" alternating magnetic poles of the annular magnetic inserts 11 is also carried out over the radial pole protrusions of the annular magnetic circuits 5 modules of the stator carrier assembly, causing pulsations of the rotating magnetic flux both in magnitude and direction in the radial pole protrusions of the said annular magnetic circuits 5. In this case, alternating electromotive forces (EMF) are induced in the armature windings 7 and 8 of the stator with a mutual phase shift in each of the m-phase anchor windings 7 and 8 at an angle equal to 360/m electrical degrees, and for the presented three-phase anchor windings 7 and 8 in their phases (A1, B1, C1 and A2, B2, C2) sinusoidal alternating electromotive forces are induced forces (EMF) with a phase shift between themselves by an angle of 120 degrees and with a frequency equal to the product of the number of pairs (p) of magnetic poles in the annular magnetic insert 11 by the rotational speed of the annular rotors 10 (for the number of pairs of magnetic poles p = 8, variable EMF is induced predominantly increased frequency, for example with a frequency of 400 Hz). Alternating current (for example, three-phase or, in general, m-phase) flowing through a common stator armature winding formed by the above connection between the same phases (A1, B1, C1 and A2, B2, C2) of armature windings 7 and 8 in adjacent ring magnetic cores 5, is fed to the output electrical power connectors (not shown in the drawing) for connecting receivers electrical energy alternating current (for example, for connecting electric motors, power tools, electric pumps, heating appliances , as well as for connecting electric welding equipment, etc.). In the presented embodiment of the synchronous generator, the output phase voltage (Uf) in the common stator armature winding (formed by the corresponding above-mentioned connection between the same phases of the armature windings 7 and 8 in the ring magnetic circuits 5) in the initial initial position of the modules of the stator bearing assembly (without angular displacement of each relative to each other of these modules of the stator carrier assembly and, accordingly, without angular displacement relative to each other of the annular magnetic cores 5 with pole protrusions along the periphery) is equal to the modulo sum of the individual phase voltages (Uf1 and Uf2) in the armature windings 7 and 8 of the annular magnetic cores of the modules of the stator carrier assembly (in In the general case, the total output phase voltage Uf of the generator is equal to the geometric sum of the voltage vectors in the individual phases of the same name A1, B1, C1 and A2, B2, C2 of the armature windings 7 and 8, see Fig.7 and 8 with voltage diagrams). If it is necessary to change (reduce) the magnitude of the output phase voltage Uph (and, accordingly, the output linear voltage U l) of the presented synchronous generator to power certain receivers of electricity with reduced voltage (for example, for electric arc welding with alternating current in certain modes), an angular rotation of individual modules of the carrier node is carried out stator relative to each other at a certain angle (given or calibrated). In this case, the locking element 27 of the nut 22 of the screw mechanism of the drive for the angular rotation of the modules of the stator bearing assembly is unlocked and, by means of the handle 32, the lead screw 21 of the screw mechanism is rotated, as a result of which the angular movement of the nut 22 along the arc of a circle in the slot "g" of the support bar 24 and the turn at a given angle of one of the modules of the stator carrier assembly with respect to another module of this stator carrier assembly around the axis O-O1 of the support shaft 9 the other module of the stator bearing assembly with the support bar 24, having a slot "g", is in a fixed position, i.e. fixed on any base, not shown conventionally in the presented drawing). With an angular turn of the modules of the stator bearing assembly (annular bushings 12 with cups 14) relative to each other around the axis O-O1 of the support shaft 9, the annular magnetic cores 5 with pole protrusions along the periphery are also rotated relative to each other at a given angle, as a result of which the turn is also carried out at a given angle relative to each other around the axis O-O1 of the support shaft 9 of the pole protrusions themselves (not shown conventionally in the drawing) with electric coils 6 of multi-phase (in this case, three-phase) armature windings 7 and 8 of the stator in ring magnetic circuits. When the pole protrusions of the annular magnetic circuits 5 are rotated relative to each other at a given angle within 360 / 2p degrees, a proportional rotation of the phase voltage vectors occurs in the armature winding of the movable module of the stator carrier unit (in this case, the phase voltage vectors Uf2 rotate in the armature winding 7 of the carrier unit module stator, which has the possibility of angular turn) at a well-defined angle within 0-180 electrical degrees (see Fig.7 and 8), which leads to a change in the resulting output phase voltage Uf of the synchronous generator depending on the electrical angle of rotation of the phase voltage vectors Uf2 in phases A2, B2, C2 of one armature winding 7 of the stator relative to the vectors of phase voltages Uph1 in phases A1, B1, C1 of the other armature winding 8 of the stator (this dependence has a design character, calculated by solving oblique triangles and is determined by the following expression:

The range of regulation of the output resulting phase voltage Uf of the presented synchronous generator for the case when Uf1=Uf2 will vary from 2Uf1 to 0, and for the case when Uf2

Execution of the stator carrier assembly from a group of identical modules with the indicated annular magnetic circuit 5 and annular rotor 10, mounted on one support shaft 9, as well as the installation of modules of the stator carrier assembly with the possibility of their rotation relative to each other around an axis coaxial with the support shaft 9, supply of modules of the stator bearing assembly kinematically connected with them by the drive of their angular turn relative to each other and the connection between the same phases of the armature windings 7 and 8 in the modules of the stator bearing assembly with the formation of common phases of the stator armature winding make it possible to expand the operational parameters of the synchronous generator by providing the possibility of regulating both its active power, and providing the possibility of regulating the output voltage of alternating current, as well as providing the possibility of using it as a source of welding current when conducting electric arc welding in various modes (by providing the possibility of adjusting the value voltage phase shift in the same phases A1, B1, C1 and A2, B2, C2, and in the general case in the phases Ai, Bi, Ci of the stator armature windings in the proposed synchronous generator). The proposed synchronous generator with excitation from permanent magnets can be used with appropriate switching of the stator armature windings to supply electricity to a wide variety of receivers of alternating multi-phase electric current with different supply voltage parameters. In addition, the additional arrangement of the same magnetic poles ("north" and, accordingly, "south") of the annular magnetic inserts 11 in adjacent annular rotors 10 is congruent to each other in the same radial planes, as well as the connection of the ends of the phases A1, B1, C1 of the armature winding 7 in the annular magnetic circuit 5 of one module of the stator carrier assembly with the beginnings of the same phases A2, B2, C2 of the armature winding 8 in the adjacent module of the stator carrier assembly (series connection of the same phases of the stator armature winding of the same name) make it possible to ensure smooth and efficient regulation of the output voltage of the synchronous generator from the maximum value (2U f1, and in the general case for the number n of sections of the stator bearing assembly nU f1) to 0, which can also be used to supply electricity to special electrical machines and installations.

Claim

1. A synchronous generator with excitation from permanent magnets, containing a stator bearing assembly with support bearings, on which an annular magnetic circuit is mounted with pole protrusions along the periphery, equipped with electric coils placed on them with a multi-phase armature stator winding, mounted on a support shaft with the possibility of rotation in the mentioned support bearings around the annular stator magnetic circuit an annular rotor with an annular magnetic insert mounted on the inner side wall with magnetic poles alternating in the circumferential direction from p-pairs, covering the pole ledges with electric coils of the armature winding of the specified annular stator magnetic circuit, characterized in that the stator bearing assembly is made from a group of identical modules with the indicated annular magnetic circuit and an annular rotor mounted on one support shaft, while the modules of the stator bearing assembly are installed with the possibility of their rotation relative to each other around the axis and, coaxial with the support shaft, and equipped with a kinematically connected drive for their angular rotation relative to each other, and the same phases of the armature windings in the modules of the stator bearing unit are interconnected, forming common phases of the stator armature winding.

2. A synchronous generator with excitation from permanent magnets according to claim 1, characterized in that the same magnetic poles of the annular magnetic inserts of the annular rotors in adjacent modules of the stator carrier assembly are located congruently to each other in the same radial planes, and the ends of the armature winding phases in one carrier module of the stator assembly are connected to the beginnings of the armature winding phases of the same name in another, adjacent module of the stator carrier assembly, forming in connection with each other the common phases of the stator armature winding.

3. Synchronous generator with excitation from permanent magnets according to claim 1, characterized in that each of the modules of the stator carrier assembly includes an annular bushing with an outer thrust flange and a cup with a central hole in the end, and the annular rotor in each of the modules of the stator carrier assembly includes an annular shell with an internal thrust flange, in which the said corresponding annular magnetic insert is installed, while the said annular bushings of the modules of the stator bearing assembly are associated with their inner cylindrical side wall with one of the mentioned support bearings, the other of which are associated with the walls of the central holes in the ends of the specified corresponding glasses, the annular shells of the annular rotor are rigidly connected to the support shaft by means of fasteners, and the annular magnetic circuit in the corresponding module of the stator bearing assembly is mounted on the specified annular sleeve, rigidly fastened with its outer thrust flange to the side cylindrical wall of the stack ana and forming, together with the latter, an annular cavity in which the indicated corresponding annular magnetic circuit with electric coils of the corresponding stator armature winding is placed.

4. A synchronous generator with excitation from permanent magnets according to any one of claims 1-3, characterized in that each of the fasteners connecting the annular shell of the annular rotor with the support shaft includes a hub mounted on the support shaft with a flange rigidly fastened to the internal thrust flange of the corresponding annular shell.

5. A synchronous generator with excitation from permanent magnets according to claim 4, characterized in that the drive for angular rotation of the modules of the stator carrier assembly relative to each other is mounted by means of a support assembly on the modules of the stator carrier assembly.

6. A synchronous generator with excitation from permanent magnets according to claim 5, characterized in that the drive for angular rotation relative to each other of the modules of the stator carrier assembly is made in the form of a screw mechanism with a lead screw and a nut, and the reference assembly for the angular rotation drive of the modules of the stator carrier assembly includes a support lug fixed on one of the mentioned cups, and a support bar on the other cup, while the lead screw is pivotally connected by a two-stage hinge at one end through an axis parallel to the axis of the mentioned support shaft, with the specified support bar made with a guide slot located along the arc of a circle, and the nut of the screw mechanism is pivotally connected at one end with the said lug, is made at the other end with a shank passed through the guide slot in the support bar, and is provided with a locking element.

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Synchronous machines with permanent magnets (magnetoelectric) do not have an excitation winding on the rotor, and the exciting magnetic flux is created by permanent magnets located on the rotor. The stator of these machines is of conventional design, with a two- or three-phase winding.

These machines are most often used as small power engines. Synchronous generators with permanent magnets are used less frequently, mainly as stand-alone generators of increased frequency, low and medium power.

Synchronous magnetoelectric motors. These motors are widely used in two designs: with radial and axial arrangement of permanent magnets.

At radial arrangement permanent magnets, the rotor package with the starting cage, made in the form of a hollow cylinder, is fixed on the outer surface of the pronounced poles of the permanent magnet 3. Interpolar slots are made in the cylinder to prevent the permanent magnet flux from closing in this cylinder (Fig. 23.1,).

At axial location magnets, the design of the rotor is similar to the design of the rotor of an asynchronous squirrel-cage motor. Ring permanent magnets are pressed to the ends of this rotor (Fig. 23.1, ).

Designs with an axial location of the magnet are used in small-diameter motors with a power of up to 100 W; designs with a radial arrangement of magnets are used in larger diameter motors with a power of up to 500 W or more.

The physical processes that occur during the asynchronous start of these motors have a certain peculiarity due to the fact that magnetoelectric motors are started in an excited state. The field of a permanent magnet during the acceleration of the rotor induces an EMF in the stator winding
, the frequency of which increases in proportion to the rotor speed. This EMF induces a current in the stator winding, which interacts with the field of permanent magnets and creates brake moment
, directed against the rotation of the rotor.

Rice. 23.1. Magnetoelectric synchronous motors with radial (a) and

axial (b) arrangement of permanent magnets:

1 - stator, 2 - squirrel-cage rotor, 3 - permanent magnet

Thus, when accelerating a permanent magnet motor, two asynchronous moments act on its rotor (Fig. 23.2):
(from current , entering the stator winding from the network) and brake
(from current induced in the stator winding by a permanent magnet field).

However, the dependence of these moments on the frequency of rotation of the rotor (slip) is different: the maximum torque
corresponds to a significant frequency (small slip), and the maximum braking torque M T - low speed (large slip). The acceleration of the rotor occurs under the action of the resulting torque
, which has a significant "dip" in the zone of low rotational frequencies. From the curves shown in the figure, it can be seen that the influence of the moment
on the starting properties of the engine, in particular at the time of entering synchronism M in, much.

To ensure a reliable start of the motor, it is necessary that the minimum resulting torque in asynchronous mode
and the moment of entering synchronism M in , were greater than the load moment. The shape of the curve of the asynchronous moment of the magnetoelectric

Fig.23.2. Graphs of asynchronous moments

magnetoelectric synchronous motor

of the engine largely depends on the active resistance of the starting cell and on the degree of engine excitation, characterized by the value
, Where E 0 - EMF of the stator phase, induced in the idle mode when the rotor rotates with a synchronous frequency. With the increase "failure" in the torque curve
increases.

Electromagnetic processes in magnetoelectric synchronous motors are in principle similar to processes in synchronous motors with electromagnetic excitation. However, it must be borne in mind that permanent magnets in magnetoelectric machines are subject to demagnetization by the action of the magnetic flux of the armature reaction. The starting winding somewhat weakens this demagnetization, since it has a shielding effect on the permanent magnets.

The positive properties of magnetoelectric synchronous motors are increased stability of operation in synchronous mode and uniformity of rotational speed, as well as the ability to rotate several motors connected to one network in-phase. These motors have relatively high energy performance (efficiency and
,).

The disadvantages of magnetoelectric synchronous motors are the increased cost compared to other types of synchronous motors, due to the high cost and complexity of processing permanent magnets made from alloys with high coercive force (alni, alnico, magnico, etc.). These motors are usually manufactured for low power and are used in instrument making and in automation devices to drive mechanisms that require a constant speed.

Synchronous magnetoelectrictrical generators. The rotor of such a generator is performed at low power in the form of an "asterisk" (Fig. 23.3, A), at medium power - with claw-shaped poles and a cylindrical permanent magnet (Fig. 23.3, b). The claw-pole rotor makes it possible to obtain a generator with pole dissipation, which limits the surge current in the event of a sudden short circuit of the generator. This current poses a great danger to the permanent magnet due to its strong demagnetizing effect.

In addition to the shortcomings noted when considering magnetoelectric synchronous motors, generators with permanent magnets have another drawback due to the lack of an excitation winding, and therefore voltage regulation in magnetoelectric generators is practically impossible. This makes it difficult for the generator voltage to stabilize when the load changes.

Fig.23.3. Rotors of magnetoelectric synchronous generators:

1 - shaft; 2 - permanent magnet; 3 - pole; 4 – non-magnetic sleeve

Generator A device that converts one form of energy into another.
In this case, we consider the conversion of mechanical energy of rotation into electrical energy.

There are two types of such generators. Synchronous and asynchronous.

Synchronous generator. Operating principle

A distinctive feature of a synchronous generator is a rigid connection between the frequency f variable EMF induced in the stator winding and rotor speed n, called the synchronous speed:

n = f/p

Where p- the number of pairs of poles of the stator and rotor windings.
Usually the rotational speed is expressed in rpm, and the EMF frequency in Hertz (1 / sec), then for the number of revolutions per minute the formula will take the form:

n = 60f/p

On fig. 1.1 shows a functional diagram of a synchronous generator. On the stator 1 there is a three-phase winding, which does not fundamentally differ from the similar winding of an asynchronous machine. An electromagnet with an excitation winding 2 is located on the rotor, which is powered by direct current, as a rule, through sliding contacts made by means of two slip rings located on the rotor and two fixed brushes.
In some cases, in the design of the rotor of a synchronous generator, permanent magnets can be used instead of electromagnets, then the need for contacts on the shaft is eliminated, but the possibilities of stabilizing the output voltages are significantly limited.

Drive motor (PD), which is used as a turbine, internal combustion engine or other source of mechanical energy, the generator rotor is driven at a synchronous speed. In this case, the magnetic field of the rotor electromagnet also rotates at a synchronous speed and induces variable EMF in the three-phase stator winding E A , E B and E C , which, being the same in value and shifted in phase relative to each other by 1/3 of the period (120 °), form a symmetrical three-phase EMF system.

With the load connected to the stator winding terminals C1, C2 and C3, currents appear in the phases of the stator winding I A , I b, I C , which create a rotating magnetic field. The frequency of rotation of this field is equal to the frequency of rotation of the generator rotor. Thus, in a synchronous generator, the stator magnetic field and the rotor rotate synchronously. The instantaneous value of the EMF of the stator winding in the considered synchronous generator

e = 2Blwv = 2πBlwDn

Here: B– magnetic induction in the air gap between the stator core and the rotor poles, T;
l- active length of one slot side of the stator winding, i.e. stator core length, m;
w- the number of turns;
v = πDn– linear speed of movement of the rotor poles relative to the stator, m/s;
D- inner diameter of the stator core, m.

The EMF formula shows that at a constant rotor speed n the shape of the graph of the variable EMF of the armature winding (stator) is determined solely by the law of distribution of magnetic induction B in the gap between the stator and the rotor poles. If the graph of magnetic induction in the gap is a sinusoid B = Bmax sinα, then the EMF of the generator will also be sinusoidal. In synchronous machines, it is always sought to obtain an induction distribution in the gap as close to sinusoidal as possible.

So, if the air gap δ constant (Fig. 1.2), then the magnetic induction B in the air gap is distributed according to the trapezoidal law (graph 1). If the edges of the rotor poles are "beveled" so that the gap at the edges of the pole pieces is equal to δ max (as shown in Fig. 1.2), then the graph of the distribution of magnetic induction in the gap will approach a sinusoid (graph 2), and, consequently, the graph of the EMF induced in the generator winding will approach a sinusoid. EMF frequency of synchronous generator f(Hz) proportional to synchronous rotor speed n(r/s)

Where p is the number of pairs of poles.
In the generator under consideration (see Fig. 1.1) there are two poles, i.e. p = 1.
To obtain an EMF of industrial frequency (50 Hz) in such a generator, the rotor must be rotated with a frequency n= 50 rpm ( n= 3000 rpm).

Ways to excite synchronous generators

The most common way to create the main magnetic flux of synchronous generators is electromagnetic excitation, which consists in the fact that an excitation winding is placed on the rotor poles, when a direct current passes through it, MMF occurs, which creates a magnetic field in the generator. Until recently, to power the field winding, mainly special DC generators of independent excitation, called exciters, were used. IN(Fig. 1.3, a). Excitation winding ( OV) is powered by another generator (parallel excitation) called a subexciter ( PV). The rotor of the synchronous generator, exciter and subexciter are located on a common shaft and rotate simultaneously. In this case, the current enters the excitation winding of the synchronous generator through slip rings and brushes. To control the excitation current, adjusting rheostats are used, which are included in the excitation circuit of the exciter r 1 and subexciter r 2. In synchronous generators of medium and high power, the process of regulating the excitation current is automated.

In synchronous generators, a non-contact electromagnetic excitation system has also been used, in which the synchronous generator does not have slip rings on the rotor. In this case, a reversed synchronous alternator is used as an exciter. IN(Fig. 1.3, b). Three-phase winding 2 exciter, in which the variable EMF is induced, is located on the rotor and rotates together with the excitation winding of the synchronous generator and their electrical connection is carried out through a rotating rectifier 3 directly, without slip rings and brushes. DC supply of the field winding 1 exciter B is carried out from the subexciter PV- DC generator. The absence of sliding contacts in the excitation circuit of the synchronous generator makes it possible to increase its operational reliability and efficiency.

In synchronous generators, including hydrogenerators, the self-excitation principle has become widespread (Fig. 1.4, a), when the AC energy necessary for excitation is taken from the stator winding of the synchronous generator and through a step-down transformer and a rectifier semiconductor converter PP converted to DC power. The principle of self-excitation is based on the fact that the initial excitation of the generator occurs due to the residual magnetism of the machine.

On fig. 1.4, b shows a block diagram of the automatic self-excitation system of a synchronous generator ( SG) with rectifier transformer ( WT) and thyristor converter ( TP), through which AC power from the stator circuit SG after conversion to direct current, it is fed into the excitation winding. The thyristor converter is controlled by an automatic excitation controller ARV, the input of which receives voltage signals at the input SG(via voltage transformer TN) and load current SG(from current transformer TT). The circuit contains a protection block ( BZ), which provides protection for the excitation winding ( OV) against overvoltage and current overload.

The excitation power is typically between 0.2% and 5% of the usable power (lower value applies to large generators).
In low power generators, the principle of excitation by permanent magnets located on the rotor of the machine is used. This method of excitation makes it possible to save the generator from the excitation winding. As a result, the design of the generator is greatly simplified, becomes more economical and reliable. However, due to the high cost of materials for the manufacture of permanent magnets with a large supply of magnetic energy and the complexity of their processing, the use of permanent magnet excitation is limited to machines with a power of no more than a few kilowatts.

Synchronous generators form the basis of the electric power industry, since almost all electricity in the world is generated by synchronous turbo or hydro generators.
Also, synchronous generators are widely used as part of stationary and mobile electrical installations or stations complete with diesel and gasoline engines.

asynchronous generator. Differences from synchronous

Asynchronous generators fundamentally differ from synchronous ones in the absence of a rigid relationship between the rotor speed and the generated EMF. The difference between these frequencies is characterized by the coefficient s- sliding.

s = (n - nr)/n

Here:
n- frequency of rotation of the magnetic field (EMF frequency).
n r- frequency of rotation of the rotor.

More details on the calculation of slip and frequency can be found in the article: asynchronous generators. Frequency .

In normal mode, the electromagnetic field of an asynchronous generator under load exerts a braking torque on the rotation of the rotor, therefore, the frequency of the change in the magnetic field is less, so the slip will be negative. Generators operating in the region of positive slips include asynchronous tachogenerators and frequency converters.

Asynchronous generators, depending on the specific conditions of use, are made with a squirrel-cage, phase or hollow rotor. The sources of formation of the necessary excitation energy of the rotor can be static capacitors or valve converters with artificial switching of valves.

Asynchronous generators can be classified according to the method of excitation, the nature of the output frequency (changing, constant), the method of voltage stabilization, slip working areas, design and number of phases.
The last two features characterize the design features of the generators.
The nature of the output frequency and methods of voltage stabilization are largely determined by the way the magnetic flux is generated.
Classification according to the method of excitation is the main one.

It is possible to consider generators with self-excitation and with independent excitation.

Self-excitation in asynchronous generators can be organized:
a) using capacitors included in the stator or rotor circuit or simultaneously in the primary and secondary circuits;
b) by means of valve converters with natural and artificial switching of valves.

Independent excitation can be carried out from an external source of alternating voltage.

According to the nature of the frequency, self-excited generators are divided into two groups. The first of them includes sources of practically constant (or constant) frequency, the second variable (adjustable) frequency. The latter are used to power asynchronous motors with a smooth change in speed.

It is planned to consider in more detail the principle of operation and design features of asynchronous generators in separate publications.

Asynchronous generators do not require complex components in the design for organizing DC excitation or the use of expensive materials with a large supply of magnetic energy, therefore they are widely used by users of mobile electrical installations due to their simplicity and unpretentiousness in maintenance. They are used to power devices that do not require a rigid binding to the current frequency.
The technical advantage of asynchronous generators can be recognized as their resistance to overloads and short circuits.
Some information on mobile generator sets can be found on the page:
Diesel generators.
asynchronous generator. Characteristics .
asynchronous generator. Stabilization.

Comments and suggestions are accepted and welcome!

Synchronous generators

with permanent magnet excitation

(developed in 2012)

The proposed generator according to the principle of operation is a synchronous generator with excitation from permanent magnets. NeFeB composition magnets that create a magnetic field with an induction of 1.35 Tl, located around the circumference of the rotor with alternating poles.

E is excited in the windings of the generator. ds, the amplitude and frequency of which are determined by the speed of rotation of the generator rotor.

The design of the generator does not contain a collector with breakable contacts. The generator also does not have excitation windings that consume additional current.

Advantages of the generator of the proposed design:

1. It has all the positive features of permanent magnet synchronous generators:

1) lack of current collector brushes,

2) lack of excitation current.

2. Most of the similar currently produced generators with the same power have mass and size parameters 1.5 - 3 times larger.

3. Rated rotation speed of the generator shaft - 1600 about./min. It corresponds to the rotation speed of low-speed diesel drives. Therefore, when transferring individual power plants from gasoline engines to diesel ones using our generator, the consumer will receive significant fuel savings and, as a result, the cost per kilowatt-hour will decrease.

4. The generator has a small starting torque (less than 2 N×m), i.e. for start-up, a drive power of only 200 Tue, and starting the generator is possible from the diesel itself at the start, even without a clutch. Similar market engines have an accelerating period to create a reserve of power when starting the generator, since the gasoline engine runs in a power deficit mode when starting.

5. With a reliability level of 90%, the generator resource is 92 thousand hours (10.5 years of non-stop operation). The cycle of operation of the drive engine between overhauls, declared by the manufacturers (as well as market analogues of the generator) is 25-40 thousand hours. That is, our generator in terms of operating time reliability exceeds the reliability of serial engines and generators by 2-3 times.

6. Ease of manufacture and assembly of the generator - the assembly site can be a locksmith workshop for piece and small-scale production.

7. Easy alternator adaptation to AC output voltage:

1) 36 IN, frequency 50 - 400 Hz

2) 115 IN, frequency 50 - 400 Hz(aerodrome power plants);

3) 220 IN, frequency 50 - 400 Hz;

4) 380 IN, frequency 50 - 400 Hz.

The basic design of the generator allows you to tune the manufactured product to different frequencies and different voltages without changing the design.

8. High fire safety. The proposed generator cannot become a source of fire even if there is a short circuit in the load circuit or in the windings, which is incorporated in the system design. This is very important when using a generator for an onboard power plant in a confined space of a water vessel, aircraft, as well as private wooden housing construction, etc.

9. Low noise.

10. High maintainability.

0.5 generator parameters kW

Parameters of the generator with a power of 2.5 kW

RESULTS:

The proposed generator can be manufactured for use in electric generator sets with a shaft speed of 1500-1600 rpm. - in diesel, gasoline and steam generator power plants for individual use or in local energy systems. Paired with a multiplier, an electromechanical energy converter can also be used to generate electricity in low-speed generator systems, such as wind farms, wave power plants, etc. of any power. That is, the scope of the electro-mechanical converter makes the proposed complex (multiplier-generator) universal. The weight, size and other electrical parameters given in the text give the proposed design a clear competitive advantage in the market compared to analogues.

The manufacturing principles underlying the design are highly manufacturable, basically do not require a precision machine park and are focused on mass mass production. As a result, the design will have a low cost of mass production.

Dmitry Levkin

The main difference between a permanent magnet synchronous motor (PMSM) is the rotor. Studies have shown that the PMSM has about 2% more than a high efficiency (IE3) asynchronous motor, provided that the stator is of the same design and the same is used for control. At the same time, synchronous electric motors with permanent magnets, in comparison with other electric motors, have the best indicators: power / volume, moment / inertia, etc.

Structures and types of permanent magnet synchronous motor

A permanent magnet synchronous motor, like any motor, consists of a rotor and a stator. The stator is the fixed part, the rotor is the rotating part.

Usually the rotor is located inside the stator of the electric motor, there are also designs with an external rotor - reverse type electric motors.

Designs of a permanent magnet synchronous motor: on the left - standard, on the right - reversed.

Rotor consists of permanent magnets. Materials with high coercive force are used as permanent magnets.

According to the design of the rotor, synchronous motors are divided into:

An electric motor with implicit poles has an equal inductance along the longitudinal and transverse axes L d \u003d L q, while for an electric motor with pronounced poles, the transverse inductance is not equal to the longitudinal L q ≠ L d .

Cross section of rotors with different Ld/Lq ratio. Magnets are shown in black. Figures e, f show axially layered rotors, figures c and h show rotors with barriers.

Also, according to the design of the rotor, the SDPM are divided into:
• synchronous motor surface mounted permanent magnets
  (English SPMSM - surface permanent magnet synchronous motor) ;
• synchronous motor with built-in(incorporated) magnets
  (English IPMSM - interior permanent magnet synchronous motor).

Rotor of a synchronous motor with surface mounted permanent magnets

Rotor of a synchronous motor with built-in magnets

stator consists of a body and a core with a winding. The most common designs with two- and three-phase winding.

Depending on the design of the stator, a permanent magnet synchronous motor can be:
• with distributed winding;
• with concentrated winding.

Distributed call such a winding, in which the number of slots per pole and phase Q = 2, 3, ...., k.

Focused they call such a winding in which the number of slots per pole and phase Q \u003d 1. In this case, the slots are evenly spaced around the circumference of the stator. The two coils forming the winding can be connected either in series or in parallel. The main disadvantage of such windings is the impossibility of influencing the shape of the EMF curve.

Scheme of a three-phase distributed winding

Scheme of a three-phase lumped winding

Form of back EMF electric motor can be:
• trapezoidal;
• sinusoidal.

The shape of the EMF curve in the conductor is determined by the distribution curve of the magnetic induction in the gap along the stator circumference.

It is known that the magnetic induction in the gap under the pronounced pole of the rotor has a trapezoidal shape. The EMF induced in the conductor has the same form. If it is necessary to create a sinusoidal EMF, then the pole pieces are shaped in such a way that the induction distribution curve would be close to sinusoidal. This is facilitated by the bevels of the pole pieces of the rotor.

The principle of operation of a synchronous motor is based on the interaction of the stator and the constant magnetic field of the rotor.

Run

Stop

Rotating magnetic field of a synchronous motor

The magnetic field of the rotor, interacting with the synchronous alternating current of the stator windings, according to, creates, causing the rotor to rotate ().

Permanent magnets located on the PMSM rotor create a constant magnetic field. At a synchronous speed of rotation of the rotor with the stator field, the poles of the rotor interlock with the rotating magnetic field of the stator. In this regard, the PMSM cannot start itself when it is connected directly to a three-phase current network (current frequency in the network is 50 Hz).

Permanent magnet synchronous motor control

A permanent magnet synchronous motor requires a control system, such as a servo drive, for example. At the same time, there are a large number of ways to control the implemented control systems. The choice of the optimal control method mainly depends on the task that is set for the electric drive. The main control methods of a permanent magnet synchronous motor are shown in the table below.

Popular ways to control a permanent magnet synchronous motor

To solve simple problems, trapezoidal control by Hall sensors is usually used (for example, computer fans). For applications that require maximum performance from the drive, field-oriented control is usually selected.

Trapezoidal control

One of the simplest methods for controlling a permanent magnet synchronous motor is trapezoidal control. Trapezoidal control is used to control PMSM with trapezoidal back EMF. At the same time, this method also allows you to control the PMSM with a sinusoidal back EMF, but then the average torque of the electric drive will be lower by 5%, and the torque ripple will be 14% of the maximum value. There is trapezoidal control without feedback and with feedback on the position of the rotor.

Control no feedback is not optimal and can lead to the PMSM getting out of synchronism, i.e. to loss of control.

Control with feedback can be divided into:
• trapezoidal control by position sensor (usually by Hall sensors);
• trapezoidal control without encoder (sensorless trapezoidal control).

As a rotor position sensor in trapezoidal control of a three-phase PMSM, three Hall sensors built into the electric motor are usually used, which allow you to determine the angle with an accuracy of ±30 degrees. With this control, the stator current vector takes only six positions per electrical period, resulting in torque ripples at the output.

There are two ways to determine the position of the rotor:
• by position sensor;
• sensorless - by real-time calculation of the angle by the control system based on the available information.

Field-oriented control of PMSM by position sensor

The following types of sensors are used as an angle sensor:
• inductive: sine-cosine rotating transformer (SKVT), reductosin, inductosin, etc.;
• optical;
• magnetic: magnetoresistive sensors.

Field-oriented control of PMSM without encoder

Due to the rapid development of microprocessors since the 1970s, sensorless vector methods for controlling brushless AC began to be developed. The first sensorless angle detection methods were based on the property of an electric motor to generate back EMF during rotation. The back EMF of the motor contains information about the position of the rotor, so by calculating the value of the back EMF in a stationary coordinate system, you can calculate the position of the rotor. But when the rotor is not moving, there is no back EMF, and at low speeds, the back EMF has a small amplitude, which is difficult to distinguish from noise, so this method is not suitable for determining the position of the motor rotor at low speeds.

There are two common options for launching the PSDM:
• scalar triggering - triggering on a predetermined voltage versus frequency characteristic. But scalar control greatly limits the capabilities of the control system and the parameters of the electric drive as a whole;
• - works only with PMSM in which the rotor has pronounced poles.

Currently only possible for motors with a rotor with pronounced poles.