The fluidity of the magnetic field wrapping is forged. Electric gravity is not simple. Induction regulators and phase regulators

In inductive electric machines, the stator and rotor windings are connected by a magnetic field. In order for this connection to be wrapped around the machine, unbreakable in the wind gap of the machine behind the additional system of stator windings, close turns around magnetic field.

Underneath we will understand such a magnetic field, the induction vector of which moves in space (in a plane perpendicular to the rotor axis) with great fluidity. If the amplitude of the induction vector is constant, then this field is called in a circle. The Obertian magnetic field can be created:

• with a changeable flow in a two-phase system of windings inserted at 90°;
• three-phase alternating flow in a three-phase system of windings, inserted in a space of 120 °;
• in a steady stream, it alternates sequentially along the windings distributed along the motor stator bore;
• a steady stream that alternates behind the additional commutator along the winding pins, which are spread along the surface of the rotor (armature). Shaping of the overt magnetic field in a two-phase machine
• (Small. 1.2). IN In such a machine, the axes of the windings are broken geometrically at 90 ° (the machine is seen with one pair of poles, r p = 1). The stator windings are supplied with a two-phase voltage, as shown in Fig. 1.2, i. When considering a machine that is symmetrical and unsaturated, it is important that the currents in the windings are also disrupted by 90 electrical degrees (90° el.) And the magnetomotive force of the windings is proportional to the current (Fig. 1 .2,6). IN the moment of the hour, = 0 strings per winding A is equal to zero, and the strum is in the winding b has the greatest negative value.

Small 1.2. Formation of the overt magnetic field in a two-phase electric machine: a - circuit diagram of the windings: b - system of two-phase strims in the stator windings: V- expansive vector diagram of magnetically moving forces generated by the stator windings

Also, the total vector of magnetic moving forces (MDF) of the windings at the time of the hour, equal to t and expansion in space, as shown in Fig. 1.2, V. At the moment h 2 = 7s / streams in the windings will be folded Tl m / And then, the summary vector of the MDS will turn around To / It will occupy the position shown in Fig. 12, V, yak 2 = 2 + 2. Y moment

hour s 2 = i / 2 the total vector of the MMF will be more expensive. Similarly, you can calculate how the position of the total MMF vector changes at an instant, etc. It can be seen that the vector wraps around in space at a speed of = 2TS, preserving its amplitude as a constant one. Directly wraps the field - behind the Godinnik arrow. It is possible to reconvert, which is applied to the phase A voltage = (зі -), and per phase b voltage = zi, then straight

The wrapper will change to the bedsheet.

Small 1.3. Schemes for switching on the windings of a three-phase motor: a - distribution of the motor windings at p p = 1; b - connection of the windings to the mirror; V- diagrams of three-phase flows in the motor windings

Thus, the expansion of the space between the axes of the windings by 90 geometric degrees (90°) and the phase change of the alternating flow in the windings by (90° electrical degrees) allows the formation of a magnetic field that wraps around the circle torus in the windy gap of the machine.

Mechanism for forming an overburden magnetic field in a three-phase changer machine. The windings of the machine are broken at 120° (Fig. 1.3, a) and are supplied by a three-phase voltage system. The currents in the windings of the machine are destroyed by 120°. (Fig. 1.3, V):

The resulting MMF vector of the stator windings is:

de w- number of turns of windings.

Let's take a look at the position in space of the vector at the time of the hour (Fig. 1.4, o). Vector MMF of the winding about t straightening along the axis about in the positive direction and direction 0, w, tobto Oh. Vector MDS winding h, Straightening along the axis h and is equal to 0. The sum of vectors j and j is straightened along the axis b in the negative direction and with this sum, the MMF vector of the winding is formed b, equal The sum of three vectors creates a vector X= 3/2, which is borrowed at the time, position, as shown in Fig. 1.4, o. Z plinom = l / ZSO (at a frequency of 50 Hz after 1/300 s) the moment comes at hour 2, when the vector of the MMF of the windings is equal, and the vector of the MMF of the windings bі h rivni - 0.5. The resulting vector of MMF 2 at the moment of position 2 is shown in Fig. 1.4,5, to move along the front to the forward position at at the cut 60° behind the anniversary arrow. It doesn’t matter if it changes, but at the moment of hour 3 the resulting MMF vector of the stator windings is in position 3, so that it will continue to move behind the year arrow. For an hour, the period of life voltage = 2l / s = 1 / the resulting MMF vector generates a new revolution, so that the winding speed of the stator field is directly proportional to the frequency of the flow in its windings and is proportional to the number of pole pairs:

de n - the number of pairs of poles of the machine.

If the number of pole pairs of the motor is greater than one, then the number of winding sections distributed along the stator core increases. So, if the number of pole pairs n = 2, then three phase windings will be distributed on one half of the stator column and three on the other. In this case, during one period of the life voltage, the resulting vector of the MMF will be generated by the rotation and the speed of the magnetic field of the stator will be twice as low, lower in machines with "= 1

Small 1.4.A- z = 7s / b- z = l / V- z = 7s /

The operation of almost all rotary motors is based on: synchronous electromagnetic motors (SM), permanent magnet motors (PMSM), synchronous reluctance motors (SRM), and asynchronous motors (AM). the principle of creation of the overt magnetic field.

Zgіtnoye with the principles of Elektrodinami in the mustache of the Extrical Dvigs (KRIM of the reactive), the ectomagnium moment is the result of mutual magnesite streaming (on the background), storage in the curtain part of the Elektrodgun. The moment of the new addition of vectors of these flows, which is shown in Fig. 1.5, and the value of the moment is the additional addition of modules of flow vectors to the sine of the space zone 0 between the flow vectors:

de before - constructive coefficient.

Small 1.5.

synchronous(SD, SDPM, SRD) i asynchronous motors The design of the stators is practically the same, and the rotors are different. The divisions of the stator windings of these electric motors fit into an equally large number of closed stator slots. If the inflow of harmonics to Zubtsov is not included, the stator windings form a magnetic flux that is constant in amplitude, which results in a constant fluidity, which is indicated by the frequency of the current. In real structures, the presence of grooves and teeth in the stator leads to the appearance of high harmonics and magnetize forces, which lead to pulsation of the electromagnetic moment.

On the rotor of the SD, the alarm winding is rotated, which is characterized by a constant current from the independent voltage source - the alarm. The wake-up stream creates an electromagnetic field, keeps the rotor unbroken and wraps itself in the wind gap simultaneously with the rotor due to fluidity [see. (1.7)]. For synchronous motors with power up to 100 kW, the excitation is based on permanent magnets installed on the rotor.

The magnetic power lines of the rotor field, created by the excitation winding or permanent magnets, “float” with the synchronously wrapped electromagnetic field of the stator. Interaction of stator fields X Rotor 0 creates an electromagnetic torque on the shaft of a synchronous machine.

When there is no pressure on the shaft, the field vectors of the stator and rotor 0 are in space and tightly wrapped around the fluidity of 0 (Fig. 1.6, a).

When the torque is added to the motor shaft, the support vector [i 0 diverges (stretches like a spring) to cut 0, and the resentment of the vector continues to turn around with a new stiffness from 0 (Fig. 1 .6,6). If cut 0 is positive, then the synchronous machine operates in ruchy mode. Changing the tension on the motor shaft is indicated by changing the cutout 0 Maximum torque M will be at 0 = l; / (0 - electrical degrees). yakscho

The position on the engine shaft moves M then the synchronous mode is destroyed and the motor falls out of synchronization. When the value is set to 0, the synchronous machine will operate as a generator.

Small 1.6.A- at ideal idle speed; b - when attached to the shaft

Reactive synchronous motor - This is a motor with pronounced rotor poles without an excited winding, and the torque of the rotor windings is to take such a position at which the magnetic support between the excited stator winding and the rotor takes on the minimum value.

The RSD has a salient-pole rotor (Fig. 1.7). The magnetic conductivity varies along the axes. Behind the later axis d, When passing through the middle of the pole, the conductivity is maximum, and along the transverse axis q- minimal. Since all the magnetizing forces of the stator are eliminated by the heavy weight of the rotor, the curvature of the power lines of the magnetic flux is absent and the moment is equal to zero. When the flow is displaced, the stator axis is preferable to the later axis d When the magnetic field (MF) wraps around, the power lines of the flow become distorted and an electromagnetic moment arises. The highest torque at the same stator flow occurs at angle 0 = 45°.

The main advantage of an asynchronous motor over a synchronous one is that the winding fluidity of the motor rotor is not equal to the fluidity of the magnetic field that is created by the strums in the stator windings. The difference in the speed of the stator and rotor fields is called to the forges= Z - zi. Invariably, the magnetic force lines of the stator overcoat field move the conductors of the rotor winding and direct the EPC and rotor strum into it. The interaction between the stator field and the rotor flow determines the electromagnetic torque of the asynchronous motor.

Small 1.7.

It is important to separate asynchronous motors from the rotor design phaseі short-circuited rotor. For motors with a phase rotor, a three-phase winding is installed on the rotor, the ends of which are connected to contact rings, through which the rotor lances are removed from the machine for connection to starting resistors with further short-circuited windings.

In an asynchronous motor, when there is voltage on the shaft, only magnetization streams flow through the stator windings to create a head magnetic flow, and the amplitude of the flow is determined by the amplitude and frequency of the voltage. In this case, the rotor turns with the same fluidity as the stator field. Do not induce pressure in the EPC rotor windings; the rotor current flows and, therefore, the torque is equal to zero.

With additional tension, the rotor wraps more tightly, lower field, forging occurs, EPC is induced in the rotor windings, proportional to forging, and rotor jets are generated. The stator voltage, like in a transformer, increases at a unique value. The ratio of the active storage flow of the rotor to the stator flow module determines the motor torque.

What all motors have in common [except switched reluctance motors (VID)] is that the main magnetic flow in the wind gap wraps around a permanently indestructible stator and is set by the frequency of the cut-off fluid. This magnetic flow follows the rotor, which wraps around for synchronous machines with the same fluidity s = s, or for asynchronous machines with various bearings - forgings 5. The head flow is created by the power lines running The ideal time when the engine is running is idle (=). At this vector axis, the magnetizing forces of the stator and rotor converge. When tension appears on the motor shaft, the axes diverge, and the power lines bend and bend. Since the lines of force begin to speed up each other, tangential forces appear that create a torque.

In the rest of the rocks they begin to remove the stagnation valve-inductor motor. Such a motor has a salient pole stator with coil windings on the skin pole. The rotor is also salient-pole, but with a different number of poles without windings. A unipolar current is supplied to the stator windings through a special switch - a commutator, and until these poles are broken, an additional rotor tooth is attracted. Then the forward pole of the stator is destroyed. The alternation of the windings of the stator poles is carried out in line with the signals of the rotor position sensor. This, as well as the fact that the strum in the stator windings is adjusted in position at the moment of rotation, is the main difference in the type of motor.

AT VIEW (Fig. 1.8), which turns a moment proportional to the amplitude of the head flow and the stage of curvature of the magnetic force lines. On the cob, when the pole (teeth) of the rotor begins to overlap the stator pole, the curvature of the power lines is maximum, and the flow is minimal. When the overlap of the poles is maximum, the curvature of the power lines is minimal, and the amplitude of the flow increases, at which point the torque becomes approximately constant. In the case of the saturation of the magnetic system, the increase in flux is reversed, and the flow in the windings is increased. A change in torque when the rotor poles pass through the stator poles causes unevenness in the wrapping of the shaft.

Small 1.8.

In a stationary jet motor, the excitation winding is moved to the stator and the field created by this winding, indestructibly. A wraparound magnetic field is created at the anchor, the wrapping fluidity of which is similar to the traditional wrapping fluidity of the anchor, but is straightened in a symmetrical manner. This is achieved because a variable current flows through the turns of the armature winding, switched by a mechanical frequency changer - collector apparatus.

The electromagnetic moment of a stationary motor is determined by the interaction between the head flux created by the alarm winding and the flow in the turns of the armature winding: M = up to/ I

If you replace the brush-commutator apparatus of the motor of the stationary flow of the air conductors with a commutator, then we can remove Brushless motor of a stationary jet. A practical implementation of such motors is a valve motor. constructively valve motor is a three-phase synchronous machine with electromagnetic disturbances or failures from permanent magnets. The stator windings are intermixed with the help of an additional conductor ceramic switch - a commutator in position depending on the position of the motor rotor.

Umovi otrymannya:

1) presence of at least two windings;

2) the jets in the windings are out of phase

3) the axes of the windings are displaced in space.

In the trifle machine with one Palya Polysiv (p = 1) Osi windings of the guards in the spaciousness of 120 °, during the cowards of the pairs of Polusiv (p = 2) the Osi windings are a bouty zmizhcheni in the spacious on Kut 60 ° I. T.D.

Let's take a look at the magnetic field that is created behind the additional three-phase winding, which has one pair of poles (p = 1). The axes of the phase windings are displaced in space at 120 ° and the magnetic induction of the adjacent phases (BA, BB, BC) is created by them, displaced in space at 120 °.

Magnetic induction fields that are created by the skin phase, as well as voltages brought to these phases, are sinusoidal and differ in phase at 120 °.

The principle of dii

A voltage is supplied to the stator winding, a current flows through each of these windings and creates a magnetic field. The magnetic field flows into the rotor blades and, according to the law of magnetic induction, induces EPC in them. In the rotor rods, under the action of the induced EPC, a strum appears. Currents in the rotor rods create a magnetic field of the rods, which interact with the wraparound magnetic field of the stator. As a result, the force exerted on the skin, which, when combined, creates the electromagnetic torque of the rotor.

Having accepted the cob phase of induction in phase A (φA) equal to zero, we can write:

The magnetic induction of the resulting magnetic field is determined by the vector sum of these three magnetic inductions.

We know the resulting magnetic induction with the help of vector diagrams, which were created for several moments of an hour.

Draw vector diagrams

As it flows from the diagram, the magnetic induction B of the resulting magnetic field of the machine turns around, remaining unchanged in magnitude. In this way, the three-phase stator winding creates a circular overlapping magnetic field in the machine. The direction of the magnetic field depends on the order of the drawing phases. The value of the resulting magnetic induction.

The rotation frequency of the magnetic field depends on the frequency of the network and the number of pairs of poles of the magnetic field.

, [Ob/hv].

In this case, the rotation frequency of the magnetic field does not remain in the operating mode of the asynchronous machine and its application.

When analyzing the operation of an asynchronous machine, the concept of the fluidity of the magnetic field ω0, which is indicated by the relationship:

, [Rad/sec].

To equalize the frequency of the rotation of the magnetic field and the rotor-ravel coefficient, which was called the coupling and designated by a letter. Forging can be found in single units and hundreds of units.

or else

Processes in an asynchronous machine Lanzug stator

a) stator EPC.

The magnetic field, created by the stator winding, wraps around the unbreakable stator with a frequency and will be induced in the EPC stator windings. The magnitude of the EPC that is induced by this field in one phase of the stator winding is indicated by:

de: = 0.92 ÷ 0.98 - winding coefficient;

-Metering frequency;

number of turns of one phase of the stator winding;

-resulting magnetic field in the car.

b) Level of electrical phase of the stator winding.

The line is formed in analogy with a coil with a core that operates on a changeable stream.

Here there are voltage limits and voltage supply to the stator winding.

- active support of the stator winding, associated with the costs of heating the winding.

- inductance of the supports of the stator winding, connected with the flux of dissipation.

- outside the support of the stator winding.

current in the stator winding.

When analyzing robots, asynchronous machines are often used. Todi can be written:

This shows that the magnetic flux in an asynchronous machine does not depend on its operating mode, and when setting the frequency of the network, it depends only on the current value of the applied voltage. A similar relationship occurs in the same place and in another machine of the changer - in the transformer.

Electric gravity is not simple

Pay attention to the frequency of the life voltage, the pressure of the flow force on the shaft, and the number of electromagnetic poles of this motor. This actual turning frequency (or operating frequency) is always lower than the so-called synchronous frequency, which is determined solely by the parameters of the power supply and the number of poles of the stator winding of a given asynchronous motor.

In such a manner motor synchronous frequency I- this is the rotation frequency of the magnetic field of the stator winding at the rated frequency of the supply voltage, and it is slightly different from the operating frequency. As a result, the number of revolutions in the spine under pressure is always less than the so-called synchronous revolutions.

The induced picture shows how synchronous the wrapping frequency for an asynchronous motor is because the higher the number of stator poles it depends on the frequency of the life voltage: the higher the frequency, the higher the winding speed of the magnetic field. So, for example, by changing the frequency of the life voltage, the synchronous frequency of the motor changes. When this happens, the operating frequency of the motor rotor turns under pressure.

Force the stator winding of an asynchronous motor to be powered by a three-phase alternating current, which creates an overcurrent magnetic field. And the more pairs of poles there are, the less synchronous the wrapping frequency will be - the wrapping frequency of the stator magnetic field.

Most current asynchronous motors run from 1 to 3 pairs of magnetic poles, in rare cases 4, and even the more poles, the lower the efficiency factor of the asynchronous motor. However, with a smaller number of poles, the rotor wrapping speed can be changed very smoothly by changing the frequency of the life voltage.

As has already been noted above, the actual operating frequency of an asynchronous motor varies from its synchronous frequency. Why are you so excited? If the rotor turns at a frequency less synchronous, then the rotor conductors move the magnetic field of the stator with some fluidity and EPC is induced in them. This EPC creates jets in the closed conductors of the rotor, as a result of which these jets interact with the wraparound magnetic field of the stator, and a torque is generated - the rotor collapses with the magnetic field of the stator.

If the moment is of sufficient magnitude to reduce the friction force, then the rotor begins to turn, at which the electromagnetic moment is equal to the galvanizing moment created by the friction force, rubbing force, etc.

When the rotor remains exposed to the stator’s magnetic field for the entire hour, the operating frequency cannot reach the synchronous frequency, as if this were not the case, the EPC would no longer be induced in the rotor conductors, and the torque simply would not appear. In the bag, for the steering mode, enter the value of “forging” (usually 2-8%), in connection with which it is true that the engine becomes uneven:

If the rotor of the same asynchronous motor is rotated with the help of some external drive, for example, an internal combustion engine, to such speed that the rotor winding frequency exceeds the synchronous frequency, then the EPC in the rotor conductors and the active flow in them will increase direct and asynchronous motor transform into.

The hidden electromagnetic moment will become galling, and the relationship will become negative. In order for the generator mode to manifest itself, it is necessary to supply the asynchronous motor with reactive pressure, which would create the magnetic field of the stator. At the time of starting such a machine in generator mode, you can remove the excess induction of the rotor and capacitors by connecting up to three phases of the stator winding in order to maintain active voltage.

A special feature of rich-phase systems is the ability to create an over-the-top magnetic field in a mechanically indestructible structure.
The coil, connected to the alternating jet, creates a pulsating magnetic field, so that the magnetic field varies in magnitude and direction.

Let's take a cylinder with an internal diameter D. On the surface of the cylinder there are three coils, the space displacement is approximately one per 120 o. The coils are connected to a three-phase voltage source (Fig. 12.1). In Fig. 12.2 readings are a schedule for changing the mitt lines to establish a three-phase system.

The skin around the cat creates a pulsating magnetic field. The magnetic fields of the coils, interacting one with another, create the resulting over-the-top magnetic field, which is characterized by the vector of the resulting magnetic induction
In Fig. 12.3 images of the magnetic induction vectors of the skin phase and the resulting vector generated for three moments of the hour t1, t2, t3. The positive alignments of the coil axes are +1, +2, +3.

At the moment t = t 1, the current and magnetic induction in the coil A-X are positive and maximum, in the coils Po-Y and C-Z - however, they are negative. The vector of the resulting magnetic induction is the same as the geometric sum of the vectors of magnetic induction of the coils and runs from the entire coil A-X. At the moment t = t 2 streams in the coils A-X and C-Z are however the same in size and the length is in the straight line. Strum is in phase B before zero. The resulting vector of magnetic induction rotates 30 o behind the year arrow. At the moment t = t 3 streams in the coils A-X and Y-Y are however in magnitude and positive, the current in the C-Z phase is maximum and negative, the vector of the resulting magnetic field is located in the negative direction of the C-Z coil axis. During the changeover period, the vector of the resulting magnetic field rotates 360 o.

The frequency of the magnetic field is synchronous or the frequency of the magnetic field is synchronous

where P is the number of pole pairs.

The cats shown in Fig. 12.1, create a bipolar magnetic field, with the number of poles 2P = 2. The frequency of the field wrapping is 3000 rpm.
To eliminate the multipolar magnetic field, it is necessary to place six coils in the middle of the cylinder, two per skin phase. Then, consistent with formula (12.1), the magnetic field will turn out twice as strong, with n 1 = 1500 rpm.
To eliminate the overt magnetic field, it is necessary to remove two minds.

1. Mother would like two spacious cat cats.

2. Connect to the coils the inescapable streams in phase.

12.2. Asynchronous motors.
Design, principle of operation

Asynchronous motor to the unrukh the part that is called stator , і Obertovo part, as it is called rotor . The stator has a winding that creates a magnetic field.
There are asynchronous motors with squirrel-cage and phase-wound rotors.
The rotor slots with short-circuited windings contain aluminum or copper wires. The ends are closed with aluminum or copper rings. The stator and rotor are made from sheets of electrical steel to reduce the cost of vortex jets.
The phase rotor carries a three-phase winding (for a three-phase motor). The ends of the phases are connected into a shaft, and the cob contains up to three contact rings located on the shaft. Place non-destructive contact brushes on the rings. A starting rheostat is connected to the brushes. After starting the engine, the support of the starting rheostat is gradually changed to zero.
The operating principle of an asynchronous motor can be seen in the model presented in Figure 12.4.

The overbert magnetic field of the stator is represented by a stationary magnet, which rotates at a synchronous winding frequency n 1.
The conductors of the closed rotor winding are induced by jets. The poles of the magnet move behind the year arrow.
The spindles, which are located on the overcoat magnet, mean that the magnet is indestructible, and the conductors of the rotor winding move against the year arrow.
The directions of the rotary jets, determined by the right-hand rule, are shown in Fig. 12.4.

Small 12.4

Using the rule of the left hand, we know directly the electromagnetic forces that act on the rotor and cause it to turn. The rotor of the motor will be wrapped at the wrapping frequency n 2 in direct wrapping of the stator field.
The rotor turns asynchronously so that the rotation frequency of n 2 is less than the rotation frequency of the stator field n 1.
The significant difference in the fluidity of the stator and rotor fields is called coupling.

The coupling cannot be equal to zero, since at the same speeds of the field and the rotor it would be necessary to induce the flows in the rotor and, therefore, there would be an electromagnetic moment that wraps around.
The moment that wraps around the electromagnetic moment is also counteracted by the galmic moment M em = M 2.
With greater tension on the motor shaft, the torque becomes greater than the torque, and the torque increases. As a result, they begin to be induced in the rotor winding EPC and jets. The moment that grows larger and becomes an equal moment of galm. The torque that turns can increase with increased torque to a small maximum value, after which, with a further increase in torque, the torque changes sharply and the engine slows down.
The forging of a galvanized engine is ancient. It appears that the motor is operating in short circuit mode.
The turning frequency of the unloaded asynchronous motor n 2 is approximately the same as the synchronous frequency n 1. The turning frequency of the unloaded motor is S 0. The motor seems to be running in idle mode.
The gearing of the asynchronous machine, which operates in motor mode, changes from zero to one.
An asynchronous machine can operate in generator mode. For this purpose, the rotor must be wrapped with a third-party motor in direct rotation of the stator magnetic field with frequency n 2> n 1. Forging an asynchronous generator.
An asynchronous machine can operate in the electric machine mode. For this purpose it is necessary to wrap the rotor in a direct line, which is the opposite direction of the magnetic field of the stator.
In this mode S> 1. As a rule, asynchronous machines are driven in motor mode. The asynchronous motor is the most widely used type of motor in industry. The field turning frequency in an asynchronous motor is closely related to the switching frequency f 1 and the number of stator pole pairs. At frequency f 1 = 50 Hz, the next series of frequencies of the wrapper begins.