RU2516286C2 - Synchronous micromotor with electromagnetic unipolar excitation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention refers to the field of electric engineering, in particular, to electric machines, and relates to manufacture of synchronous micromotor with unipolar excitation. A synchronous micromotor with unipolar excitation contains a stator with a standard core with a three-phase power winding that creates a rotary magnetic field of the stator and a direct-current excitation winding that creates an excitation flux, as well as a cylindrical solid rotor of iron-copper alloy divided by a non-magnet conductive layer into two magnet isolated parts - two cores of the rotor. According to the invention, at that in order to increase reliability of the synchronous motor operation contactless electromagnetic unipolar excitation is carried out when two cores of the rotor form two permanent magnet poles with invariable different polarity, the north N and the south S ones, at their interaction with the rotary magnetic field of the stator the synchronising torque is created and availability of solid cores at the rotor ensures asynchronous start without a starting winding.

EFFECT: improving reliability of the synchronous motor operation due to creation of permanent poles at the rotor in electromagnetic way without use of permanent magnets.

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Description

The invention relates to the field of electrical engineering, in particular, to a synchronous micromotor (SD) device with electromagnetic unipolar excitation.

Synchronous micromotors can be used in automation circuits and low-power household devices, from fractions of a watt to hundreds of watts, where the energy characteristics are not decisive. The main feature of synchronous micromotors is that the rotational speed of their rotor is equal to the rotational speed of the stator field and is rigidly connected with the frequency of the supply network [1, 2]. Non-contact LEDs with constant magnetic are widely used [4].

Known designs of contactless LEDs with magnetoelectric excitation have no field winding; their field of excitation is created by permanent magnets mounted on the rotor. The most widely used are two types of LEDs: with an axial and radial arrangement of a block of permanent magnets and a rotor package with a short-circuited winding [2]. The design with an axial arrangement of magnets is used in small diameter micromotors with a power of up to 100 W, and with a radial arrangement of magnets - in large diameter micromotors with a power of up to 500 W and more. The disadvantages of such micromotors are their high cost, manufacturing complexity and low starting quality. With asynchronous acceleration of micromotors, their resulting moment has a dip in the region of small slip [2].

The closest in technical essence to the claimed device SD is selected as a prototype non-contact LED with magnetoelectric excitation, having an explicit pole rotor with a radial arrangement of a block of permanent magnets and a rotor package with a short-circuited winding, creating a flow of excitation of the rotor and providing the occurrence of electromagnetic moment in synchronous mode [2 ]. A short-circuited squirrel cage winding, laid in a burnt package of electrical steel, provides the occurrence of an electromagnetic moment in the asynchronous start mode. The stator of the prototype is ordinary, in its grooves is a distributed winding that creates a rotating magnetic field of the stator.

The known design of LEDs has several disadvantages. Hard magnetic alloys of permanent magnets have a high cost, are difficult to machine, have low magnetic permeability, as a result of which it is impossible to make a squirrel cage in a rotor made entirely of such an alloy. Therefore, it is necessary to use pole pieces made of electrical steel, in which a short-circuited winding is placed, which complicates the design of the rotor, its manufacture and balancing. The presence of permanent magnets on the rotor during asynchronous start-up leads to the appearance of a braking torque that worsens the start-up conditions under load or makes it completely impossible, which makes the LED work unreliable. Reliability is also reduced due to the fact that under the influence of the reaction of the armature, under certain conditions, partial and sometimes irreversible demagnetization of permanent magnets can occur. To mitigate this phenomenon, it is necessary to apply special constructive measures, which ultimately causes an increase in the dimensions, weight and cost of the machine [3, 6].

The aim of the invention is to increase the reliability of a synchronous micromotor by creating permanent poles on the rotor by electromagnetic means without permanent magnets.

This goal is achieved by the fact that on the stator, in addition to the stator core of a conventional ring shape with a distributed three-phase network winding, creating a rotating magnetic field, two ring coils of the field winding (OV) are placed on both sides of the stator core, after the coils at the edges of the stator there are two end ring-shaped core, magnetically closed by packages of external magnetic circuits passing behind the stator cores. There is a non-magnetic gap between the external magnetic circuits and the stator package. End cores and packages of the external magnetic circuit form a magnetic circuit of the excitation flux on the stator. Permanent magnets and a starting cell are absent on the rotor, it is implicitly cylindrical in shape, has overhangs on both sides of the stator core, and the magnetic parts of the rotor core with overhangs form a magnetic circuit of the rotor excitation flux. At the ends there are short-circuited rings with reduced electrical resistance to weaken the transverse currents in the active zone of the rotor. The extreme parts of both flights of the rotor through the air gap are magnetically connected to the two end cores of the stator, forming a closed magnetic circuit of the excitation flux of the machine. The OB located on the stator is directly connected to a direct current source. The magnetically conductive departures of the rotor cores located inside the ring coils of the OB provide the conditions for the appearance of a unipolar magnetic flux of excitation, which closes in the above-mentioned elements of the magnetic circuit, having an axial direction, and cannot interact with the rotating radial field of the stator. In order for the rotating stator field to interact with the rotor during unipolar excitation, two permanent poles with invariably different polarity must be created on the rotor. This is achieved due to the design of the SD rotor. Its rotor is a solid massive cylinder of an iron-copper alloy with a high resistivity, divided by a non-magnetic conductive layer into two magnetically insulated parts - hereinafter two rotor cores.

In the active zone of the machine along the entire air gap between the rotor and stator cores, the magnetic coupling between the two rotor cores is through the air gap and the back of the stator core, while the excitation flows in both rotor cores change direction from axial to radial. As a result, two radial fluxes are formed in the air gap between the stator cores and the two rotor cores, one inlet and the other outgoing, so that two magnetic poles with opposite and unchanged polarity are formed on the rotor cores: one of the rotor cores is constantly the north pole N, the other constantly south S. The interaction of these "poles" of the rotor with the rotating stator field creates an electromagnetic synchronization moment, causing the rotor to rotate synchronously with the stator field.

The solid massive core of the rotor allows for asynchronous start-up without a starting cell, because its outer layers serve as a short-circuited winding.

It is the inventive device of the stator, rotor and LED excitation circuit, as well as the mutual arrangement of their elements that makes it possible to contactless electromagnetic unipolar excitation of LED, in which two permanent magnetic "poles" with constant polarity are formed on its rotor in the absence of permanent magnets, the interaction of which with a rotating field the stator creates a torque electromagnetic synchronization.

Comparison of the claimed technical solution with the prototype made it possible to establish compliance of the invention with the criterion of novelty. In the study of other well-known technical solutions in the field of synchronous micromotors, signs that distinguish the claimed device SD from the prototype were not detected. therefore, they provide the claimed device with the criterion of significant differences. The presence of a uniform air gap along the entire circumference of the stator ensures a uniform distribution of the excitation flux and the formation of a synchronization moment along the entire core, which significantly improves the performance of LEDs. The same can be achieved by regulating the magnitude of the excitation current with a rheostat in the OB circuit. With electromagnetic excitation, there is no danger of demagnetization of poles. The rotating magnetic field of the stator does not cross the turns of the organic matter and does not induce an emf in it. dangerous at the initial moment of asynchronous start-up, therefore there is no need to disconnect the OB from the power source for the start-up time and short-circuit it to an increased resistance. Asynchronous start-up of LEDs due to the massive cores of the rotor provides an increased value of the starting asynchronous moment and lowering the value of the starting current, which improves the starting properties of the LED [5].

But in the process of asynchronous acceleration of the rotor of its pole create a braking torque, causing a "failure" of the resulting torque in the low-frequency zone. Therefore, at the start-up time, it is possible to either turn off the OB completely or reduce its current by the start-up time; Regulation of the excitation current can be carried out either manually or automatically by a special regulator.

The invention is illustrated by drawings, where Fig. 1 shows a longitudinal section of a structural diagram of an LED with a bipolar stator (p = 1) and a bipolar rotor; figure 2 shows a cross section of the SD in the middle section in the active zone.

On the SD stator there is a package of the main magnetic circuit (stator core) 1 of the usual type, in the grooves of which there is a three-phase network winding 2; on both sides of the stator core there are two annular coils 3 forming an excitation winding (OB); after them at the ends, on both edges of the stator, there are two ring-shaped end cores 4, magnetically closed between each other by packages of the external magnetic circuit 5, mounted on the stator housing 6 from the outside of the stator core 1.

The rotor of the LED is an indirect pole cylindrical one, has overhangs on both sides of the stator core and consists of two massive magnetically conductive cores 7 of an iron-copper alloy separated by a non-magnetic gap 8.

At the ends of the massive cores of the rotor 7 are short-circuited rings 9 with low electrical resistance. The air gap 10 between the main magnetic circuit - the core of the stator 1 and the two cores of the rotor 7 is the active zone in which the main electromagnetic processes of diabetes occur.

The cores of the rotor 7 outside the active zone in the departures are in the form of cylinders, in the active zone, in the air gap zone, they are in the form of half-cylinders.

The extreme parts of both departures of the rotor 7 cores are magnetically connected through the air gap to two end cores 4, which are magnetically closed between each other by the packages of the external magnetic core 5. Departures of the rotor 7 cores, end cores 4 and packages of the external magnetic core 5 form the outer part of the magnetic circuit of the excitation flux. In the core due to the non-magnetic gap 8, the cores of the rotor 7 are magnetically connected to each other through the air gap 10 and the back of the stator core 1. The half cylinders of the cores of the rotor 7, the air gap 10 between them and the stator cores and the back of the stator core 1 form the inner part of the magnetic flux chain excitement. The closure paths of the excitation flux in the LED magnetic system are shown in dashed lines in FIG. 1 and FIG. 2. As can be seen from these figures, the excitation flux, being closed in the magnetic system, passes through the air gap four times, therefore, to create the required magnitude of the excitation flux in LEDs, a significant MDS of the excitation winding is required.

SD works as follows. The three-phase bipolar network winding of the stator 2 creates a rotating magnetic field. locking in the transverse plane and having radial components.

When supplying the OB with direct current, both of its coils 3, included in accordance with, create one common unipolar excitation flux in the sections of the magnetic circuit. In the external part of the magnetic circuit, the excitation flows have one direction — axial and cannot interact with the stator field. In the active zone, the excitation flows in the rotor cores change the axial direction to the radial one. The direction of the excitation flux in the sections of the magnetic circuit is shown in FIGS. 1 and 2 by dashed lines. In this case, in the air gap between the stator core and two rotor cores, two radial flows are formed, directed in opposite directions, i.e. two magnetic “poles” with opposite and unchanged polarity are formed on the rotor: one of the rotor cores is constantly the north “pole” N, the other is constantly the south S. The interaction of these “poles” - the rotor cores with the rotating stator magnetic field creates an electromagnetic synchronization moment.

The start of the LED under consideration is asynchronous, similar to the start of the AD with a massive rotor [5]. The absence of permanent magnets on the rotor significantly reduces the costs and labor costs of its manufacture, eliminates the threat of demagnetization of the poles. A massive cylindrical rotor makes the air gap uniform along the entire circumference of the stator, which significantly improves performance and allows for asynchronous start-up without a starting cell with better starting properties. The OB located on the stator can be directly connected to the power source, a massive rotor allows asynchronous start-up without a starting cell.

Information sources

1. Armensky E.V., Falk G.B. Electric micromachines. - M., 1985 .-- 231 p.

2. Bruskin D.E., Zorokhovich A.E., Khvostov B.C. Electric cars and micromachines. - M.: Higher School, 1971. - 432 p.

3. Ermolin N.P. Electric machines of low power. - M.: Higher School, 1967. - 504 p.

4. Katsman M.M. Electric cars. - M.: Academy, 2003 .-- 496 p.

5. Burial grounds B.C. Asynchronous electric motors with a two-layer rotor and their application. - M .: Energoatomizdat, 1983. - 119 p.

6. Petrov G.N. Electric cars. - M., MPEI. 1963 .-- 416 p.

Claims (1)

A synchronous micromotor (SD) with unipolar electromagnetic excitation, having on the stator: a conventional core with a three-phase network winding, creating a rotating magnetic field of the stator, two ring coils of the field winding connected to a constant current source and creating a field flow, as well as two ring cores and external magnetic circuits forming paths for the excitation flux, and a cylindrical massive rotor made of an iron-copper alloy, divided by two non-magnetic conductive layer into magnetically insulated parts - two rotor cores, characterized in that, in order to increase the reliability of the operation of LEDs, non-contact electromagnetic unipolar excitation is carried out, in which two rotor cores form two permanent magnetic poles with invariably different polarity, the north N and south S, whose interaction with the rotating the stator's magnetic field creates a synchronizing moment, and the presence of massive cores on the rotor ensures asynchronous start-up without a starting winding.

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