JPS61189156A - Induction rotary electric machine - Google Patents

Abstract

PURPOSE:To improve the utility rate of a magnetomotive force by forming a stator winding of the first and second windings having different number of poles, and disposing a rotor winding having one or more turns equally on the entire periphery in the number of average of the number of poles of the stator windings. CONSTITUTION:An induction rotary electric machine 40 is composed of a stator having a stator core 11 held in a housing 9 and a rotor having a rotor shaft 4 and a rotor core 5. The winding 10 of the stator is formed of two types of 3-phase windings 10a, 10b having different number of poles, the winding 20 of a rotor is formed of a plurality of rotor winding groups 30, and the number of the groups 3 has the number of average of the first and second stator winding poles. Further, the first winding 10a is connected with a 3-phase AC system 12, and the second winding 10b is connected through a transformer 16 and a breaker 17 with a frequency converter 13. Thus, the rotating speed can be altered by controlling the frequency of the voltage applied to the winding 10b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an induction rotating electric machine, and particularly to a brushless wound type induction rotating electric machine suitable for a drive motor of a pump, a fan, or the like.

[Background of the invention]

BACKGROUND OF THE INVENTION Conventionally, wound induction machines have been used as electric motors for driving medium to large capacity pumps and fans, and speed control has been performed using a secondary excitation control method.

However, since wound induction machines have brushes, slip rings, and fc coils, maintenance and inspection are essential. In order to eliminate this drawback,
A brushless wound induction machine, as seen in

This induction machine combines two induction machines into one, and has a double winding structure for both the stator and rotor, and the rotor windings are electrically connected, so the upper coil and the upper coil are connected in one slot. I have to store 4 coils including the bottom coil. Therefore, the winding work becomes complicated and the manufacturing cost increases.

Furthermore, there were other problems such as increased rotor winding loss.

On the other hand, as a brushless structure, a simple and robust squirrel-cage induction machine is generally known, but with this induction machine structure as it is, although primary frequency control can be performed, secondary excitation control is impossible. If this method is applied to a large-capacity variable speed system, a large-capacity control device is required, resulting in a sharp increase in cost.

In addition, a special induction machine is being considered in which the stator winding has a double winding structure and the number of rotor bars (conductor groups) is the average number of stator winding poles, but in this case, the rotor Since the number of conductors is small and the current flowing simultaneously in one conductor group can only flow in one direction, the winding coefficient is low9 and the waveform is deteriorated.
There has been a desire for a brushless induction rotating electrical machine that maintains the power factor at almost the same value as a low induction machine, is capable of secondary excitation, and has a simple rotor winding structure.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the prior art, maintain a high winding coefficient of the rotor, improve the utilization rate of magnetomotive force, and make the rotor winding a simple single winding structure while providing a brushless structure. An object of the present invention is to provide an induction rotating electric machine that can control secondary excitation.

[Summary of the Invention] That is, the present invention provides a first stator winding having a different number of poles.
．． The rotor winding structure is formed from the second stator winding and has one or more turns so that current can flow in the opposite direction through the rotor, and the pitch between the coil sides is adjusted to increase the winding coefficient. In order to simultaneously generate magnetomotive forces corresponding to the two types of stator winding pole numbers in the air gap, the rotor windings are equally spaced around the entire circumference by the average number of stator winding poles. It was designed to achieve the intended purpose by placing it in the

[Embodiments of the invention]

The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 shows a winding diagram of a stator winding and a rotor winding of an induction rotating electric machine according to the present invention, and the present invention is characterized by the winding method of both windings.

That is, the stator winding 10 is composed of two types of three-phase stator windings 10a and 10b with different numbers of poles, and the rotor winding 20 is composed of a group of rotor windings with the number of films as shown in the figure 30. and the number of winding groups has an average number of poles of the first and second stator windings.

In other words, if the number of poles PM of the first stator winding is 8 poles, the number of poles Pg of the second stator winding is 4 poles.
And the number n of rotor winding groups is as shown in equation (1), n= (PM+PK)/2=(8+4)/2=6 ・River...(1
) The feature is that there are 6 pieces.

In this figure, short-circuit IJt7a, 7b are provided at the ends in the axial direction. Further, 6a is the upper coil side of the rotor winding, and 6b is the lower coil side of the rotor winding. One winding group (coil group) starts from 7a and is wound in the order of 6a→6b→7a.

Note that αb is the pitch between coil groups, and αb −
n=2π...Group...(2). Also, βb is the coil side pitch, and β is the pitch across the coil. By changing , the winding coefficient changes. β. If designed to the highest value, PM and Pz
The gap magnetomotive force component that electromagnetically couples with increases, and other components can be significantly reduced.

FIG. 2 is a partially cutaway view of a specific induction rotating electric machine having the features shown in FIG. 1 is a rotor, 3 is a stator, and 3 is a bearing.

The rotor 1 includes a rotor shaft 4, a rotor core 5 fixed on the rotor shaft and rotating together with the rotor shaft, and a stator core 5 embedded in a slot provided near the outer periphery of the rotor core. The rotor winding 6 is arranged in a special relationship as described above. 7 is a short-circuit ring of the rotor winding, 8 is a stator core 11 that is held in rotation, and a stator winding 1o that is wound and held around the inner circumference of this stator core. It is composed of llll. In this case, in particular, the stator winding 110 is formed of two types of stator windings, ie, the first stator winding 10a and the second stator winding iob, as described above.

FIG. 3 shows a system for performing secondary excitation control on the induction rotating electric machine formed in this manner when put into practical use. 1st
The stator winding 10 a is connected to a three-phase AC system 12 , and the second stator winding 10 b is connected to a frequency converter 13 . The rotation speed can be changed by controlling the frequency of the voltage applied to the second stator winding 10b. Note that 14 is a load, and 15 is a bearing that directly connects the induction rotating electric machine 4.0 according to the present invention to the load 14. 16 is a transformer, and 17 is a breaker.

Next, the principle of operation of this induction rotating electric machine will be explained with reference to FIG.

In general, wound type induction rotary electric machines that can perform secondary control control the secondary frequency via brushes and slip rings, but in order to implement secondary excitation control without brushing, that is, without contact. First stator winding 1 described in the present invention
When 0a is the primary winding, a magnetomotive force component that responds to the second stator winding 10b must be created by the rotor current in some way. In other words,
The magnetomotive force in the air gap between the stator and rotor must contain a component corresponding to the number of poles of the first and second stator windings.

Figure 4 shows the current distribution and magnetomotive force distribution when the first stator winding is a pole and the second stator winding is four poles.
The first stator winding is called the main winding, and the second stator winding is called the excitation winding.

When a voltage is applied to the excitation winding, a spatially rotating magnetic field ΦE as shown in (a) is generated. This rotating magnetic field interlinks with the rotor winding and generates a secondary current, but if the special winding shown in Figure 1 is used, the rotor winding will generate a secondary current as shown in Figure 4 (b). A current flows. This current flows into the air gap as shown in Figure 4 (
A magnetomotive force with a distribution as shown in C) is generated. If this magnetomotive force includes not only a component corresponding to the excitation winding but also a component corresponding to the other winding, that is, the main winding, secondary excitation control becomes possible. Figure 4(d) shows the expansion of the magnetomotive force distribution in Figure 4(C) into a Fourier series. In addition to the component Φ26 corresponding to the excitation winding, a component ΦH corresponding to the main winding is generated. I know what you're doing. The portion surrounded by the two-dot chain line is the other components. Coil side pitch βb and coil straddle pitch β in FIG. If , the current path in FIG. 4(b) and the magnetomotive force distribution in FIG. 4(c) change. Here, it can be said that the optimal design is when the magnetomotive force and components of the excitation winding and the main winding are high and other components are minimal.

Next, we will examine the magnitude of the magnetomotive force component in the air gap using a theoretical formula. The magnitude of the magnetomotive force generated on the stator side by energizing the main winding (first stator winding) and the excitation winding (second stator winding) is ATM and AT+, respectively.
Let it be e. The magnetomotive force Ratl entering the rotor from the stator is RatI: ATMej (a12t-pM#R) + ATz
ej(""p"'Rl ,, ,,, ・,,
(8). However, ω2' is the rotor angular velocity, PM is the number of pole pairs of the main winding, Pg is the number of pole pairs of the excitation winding, and the excitation winding is connected in reverse phase to the main winding. On the other hand, if the magnetomotive force generated on the rotor side due to the interlinkage of the magnetomotive force on the stator side with the rotor winding is Rat2, it is expressed by the following equation.

Rat2−Σ(AT2r(n)e' ””−”θ”+A
T2b (e) e"""am weight (9) """"' (4) Here, A T 2 t is the magnitude of the positive phase component magnetomotive force, A
T 2 b is the magnitude of the reverse phase magnetomotive force, and m corresponds to the number of pole pairs of the generated magnetomotive force. Therefore, the magnetomotive force in the air gap is a combination of the equation t;Ql (4), and becomes the following equation.

Rat=Ratl+"at2 ++・++++++
+r5) Note that equations (3) to (5) are expressed in rotor coordinates.

Next, the relationship of magnetomotive force distribution will be explained with reference to FIG. As mentioned in the operating principle, in the air gap, an effective magnetomotive force component that contributes to torque generation and other components are generated, corresponding to the number of poles of the main winding and excitation winding. In the sense of determining the effective magnetomotive force component content, the magnetomotive force coefficient (h2tM+h2bM, hHJ h2b
t). When the rotor magnetomotive force is expressed using the electromotive force coefficient, the field of view is as follows.

k'r+t (PM) = hztMATM+11z
f Seal ATg・・・・・・・・・(6) AT2b (PK) =JbvATy hzbiAT
z・・・・・・・・・(7) Figure 5(C) shows the rotor magnetomotive force component when voltage is applied only to the main winding in the rotor winding in Figure 2. Most of the PM polar and Pg polar acid components are generated, and only a small amount of other components are generated. FIG. 5(d) shows the magnetomotive force component when voltage is applied only to the excitation winding, and the same can be said.

FIG. 6 shows an equivalent circuit of the induction rotating electric machine according to the present invention, and based on this, the relationship between voltages, currents, two frequencies, etc. at various parts of the two stator windings and the rotor is shown.

When a voltage VM with a frequency fM is applied to the main winding, a main winding current 1w with a frequency fM flows. This current generates a rotating magnetic field with a pole number PM, and a magnetic flux ΦV interlinks with the rotor winding. This causes current IR to flow through the rotor winding. The frequency of this current In is the average frequency SMfM. Here, the slip SM is between the main winding and the rotor. The magnetomotive force in the gap generated by this rotor current In includes a Pm component, which generates a rotating magnetic field with the number of poles Pz. This rotating magnetic field interlinks with the excitation winding, causing a current It to flow. In this figure,
'IM is the winding resistance of the main winding, XIM is the leakage reactance of the main winding, rR is the rotor winding resistance, XR is the leakage reactance of the rotor winding including leakage due to spatial harmonics, and rIg is the The winding resistance of the excitation winding, xlm, indicates the leakage reactance of the excitation winding.

If SE is the range between the excitation winding and the rotor, the frequency f of the current flowing through the excitation winding is expressed as (8).

Therefore, the rotational speed Nm of the induction rotating electric machine is as follows.If fM is the commercial frequency, the induction rotating electric machine can be operated at variable speed by controlling fl using a frequency converter. That is, secondary excitation control is possible.

According to this embodiment, the rotor has a single winding, and brushless secondary excitation control is possible. Moreover, since the rotor winding has more than one turn, it is possible to maintain a high winding coefficient (comparable to current wound rod induction machines) by adjusting the straddling pitch of the coil sides, and the utilization rate of magnetomotive force. can be improved.

Therefore, all of the problems of the conventional example, such as maintenance and inspection of the current collector, complicated rotor winding work, reduction in winding coefficient, and increase in system cost, are solved.

〔Effect of the invention〕

As described above, according to the induction rotating electrical machine of the present invention, the stator winding is formed of first and second windings each having a different number of poles, and the rotor winding has one or more turns. Since the number of poles of the stator winding is equal to the average number of poles of the stator winding, the pitch across the coil sides of the rotor winding is adjusted to maintain the winding coefficient as high as the current winding induction machine. At the same time, it is possible to obtain an induction rotary electric machine capable of controlling the rotor winding with heavy plasticine secondary excitation.

[Brief explanation of the drawing]

Figure 1 is a stator and rotor winding diagram of the induction rotating electric machine of the present invention, Figure 2 is a partially cutaway perspective view of the rotating electric machine, and Figure 3 is the secondary excitation of the rotating electric machine shown in Figures 1 and 2. A system diagram for control, Figure G4 is a diagram explaining the principle of the induction rotating electric machine according to the present invention, Figure 5 is a diagram showing the relationship between the number of coils and the magnetomotive force component in the induction rotating electric machine, and Figure 6 is an equivalent circuit of the rotating electric machine. It is. 1... Rotor, 2... Stator, 3... Bearing, 4...
... Shaft, 5... Rotor core, 6... Rotor winding, 7... Short circuit ring, 8... Reinforcement ring, 9... Housing, 11... Stator core, 10a ...First rotor winding (main winding), 10b... Second stator winding (excitation winding), 12... System bus, 13... Frequency converter, 14... ...Load, 15... Bearing, 16... Transformer, 17... Breaker.

Claims (1)

[Claims] 1. In an induction rotating electrical machine having a rotor having a rotor core and a rotor winding, and a stator core and a stator winding arranged opposite to the rotor at a predetermined interval, the stator winding is The stator windings are formed of first and second stator windings each having a different number of poles, and the rotor windings of the rotor each have at least one turn and are short-circuited to form one magnetic pole. An induction rotating electric machine characterized in that the rotor windings are equally arranged around the entire circumference by an average number of the stator winding poles.