JP2018157684A - Rotary electric machine and rotary electric machine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary electric machine capable of improving a power factor.SOLUTION: With a rotary electric machine, a stator and a rotor radially face across a gap. The stator includes: an annular core back; a stator core having teeth provided in a circumferential direction in plural so as to radially protrude from the core back; and a stator winding wound about a stator slot formed between the adjacent teeth. The teeth include projections projected further in a circumferential direction from a radially projected tip section at both sides of the circumferential direction. A magnetic body is formed between adjacent projections. When a circumferential direction component of magnetic resistance of the magnetic body is Rσ, a radial direction component of magnetic resistance of a gap is Rδ, a no-load current is I0, and a rating current is I1, a configuration includes a relation of a following formula.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an induction motor, and more particularly to a circumferential width, a radial height, and a magnetic permeability of a magnetic body located at an opening of a stator slot.

  Japanese Patent Application Laid-Open No. 7-123621 discloses background art regarding the width s / gap length δ of the opening of the stator slot and the circumferential component μsx and the radial component μsy of the magnetic permeability of the magnetic material positioned at the opening of the stator slot. A gazette (Patent Document 1) is known. In Patent Document 1, in particular, a turbine in which a short-circuit current in a power system is suppressed even in a transient state such as a short-circuit state from a no-load state, and electromagnetic force applied to the turbine generator body is reduced. In order to provide a generator, it is described that s / δ is 1 or less, and μsx> μsy is satisfied.

Japanese Patent Laid-Open No. 7-123621

  In the configuration of Patent Document 1, the ratio of s and δ or μsx and μsy is set so that magnetic flux leaking in the circumferential direction can be easily passed through the opening of the stator slot and the short-circuit current in the transient state is suppressed. Is. However, in steady state, the magnetic flux that leaks in the circumferential direction through the opening of the stator slot is easy to pass, which is accompanied by an increase in current that creates magnetic flux that does not contribute to the generation of torque, and the power factor decreases. The problem remains.

  The objective of this invention is providing the rotary electric machine and rotary electric machine system which can improve a power factor.

  In view of the above-described background art and problems, the present invention is a rotating electrical machine in which a stator and a rotor face each other in a radial direction with a gap therebetween, and the stator has an annular core back. And a stator core having a plurality of teeth provided in the circumferential direction so as to protrude from the core back in the radial direction, and a stator winding wound around a stator slot formed between adjacent teeth. The teeth are provided with convex portions projecting in the circumferential direction from the tip portion projecting in the radial direction on both sides in the circumferential direction, a magnetic material is formed between adjacent convex portions, and the circumferential component of the magnetic resistance of the magnetic material Is Rσ, the radial component of the magnetoresistance of the gap is Rδ, the no-load current is I 0, and the rated current is I 1, the following formula is established.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the rotary electric machine and rotary electric machine system which can make a power factor high.

1 is a partial cross-sectional view of an induction motor in Example 1. FIG. 1 is a magnetic circuit diagram of an induction motor in Embodiment 1. FIG. It is a figure which shows the main magnetic flux and leakage magnetic flux of the induction motor in Example 1. FIG. 1 is an equivalent circuit diagram of an induction motor in Embodiment 1. FIG. It is a figure which shows the relationship of the power factor of the induction motor in Example 1, magnetic resistance, and magnetic permeability. It is a figure which shows the relationship between the electric current of the induction motor in Example 1, and magnetic resistance. It is a figure which shows the relationship of the electric current of the induction motor in Example 2, 3 and 4, magnetic resistance, and a power factor.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

  This embodiment will be described using an induction motor which is an example of a rotating electrical machine. FIG. 1 is a partial cross-sectional view of the induction motor in the present embodiment.

  In FIG. 1, an induction motor is a rotating electrical machine in which a stator 1 and a rotor 2 are opposed to each other in a radial direction with a gap 3 therebetween. The stator 1 includes an annular core back 4 and a core back 4. A stator core 6 having a plurality of teeth 5 provided in the circumferential direction so as to protrude in the radial direction, and a stator winding 8 wound around a stator slot 7 formed between adjacent teeth 5 (see FIG. The teeth 5 are provided with convex portions 9 protruding in the circumferential direction from the tip portion protruding in the radial direction on both sides in the circumferential direction, and a magnetic body 10 is formed between the adjacent convex portions 9. ing. The magnetic body 10 is composed of magnetic powder or a magnetic plate and a non-magnetic insulator such as resin, and enhances electrical insulation and mechanical strength. Although details will be described later, when the circumferential component of the magnetic resistance of the magnetic body 10 is Rσ, the radial component of the magnetic resistance of the gap 3 is Rδ, the no-load current is I0, and the rated current is I1, Have a relationship.

  The rotor 2 includes a rotor core 11 and a rotor bar 13 housed in a plurality of rotor slots 12 arranged on the rotor core 11 at predetermined intervals in the circumferential direction.

  When the circumferential width of the stator slot 7 is reduced, the magnetic flux leaking in the circumferential direction through the stator slot 7 is easy to pass, and the current component that generates the magnetic flux that does not contribute to the generation of torque increases. The teeth 5 are provided with a convex portion 9 projecting further in the circumferential direction from a tip portion projecting in the radial direction, and the circumferential width of the stator slot 7 becomes the smallest at the position of the convex portion 9, and Magnetic flux leaking in the circumferential direction at the position is most easily passed. When the magnetic body 10 is installed between the adjacent convex portions 9, the magnetic flux leaking in the circumferential direction at the position of the convex portion 9 is further easily passed, and the current component that creates the magnetic flux that does not contribute to the generation of torque further increases.

  However, as in this embodiment, when the following formula is satisfied:

  Although the details will be described later when the magnetic body 10 is installed between the adjacent convex portions 9, the current is reduced and the power factor is improved as compared with the case where the magnetic body 10 is not provided.

  FIG. 2 is a magnetic circuit diagram of the induction motor in the present embodiment. The magnetic resistance is the difficulty of the magnetic flux of the rotating electrical machine, is proportional to the distance of the magnetic flux path, and is inversely proportional to the magnetic permeability and the cross-sectional area of the magnetic flux path. The magnetic permeability is a physical constant representing the ease of passing the magnetic flux, and the ratio when the vacuum magnetic permeability is 1 is represented by the relative magnetic permeability.

  In FIG. 2, the magnetic resistance of the magnetic body 10 per slot with respect to the magnetic flux passing through the magnetic body 10 is Rσw, the magnetic resistance of the gap 3 per 0.5 teeth with respect to the magnetic flux passing through the gap 3 is Rδt, and the magnetic body 10 and the gap 3 Rδww is the magnetic resistance of the magnetic body 10 per 0.5 slot with respect to the magnetic flux passing through, and Rδwg is the magnetic resistance of the gap 3 per 0.5 slot with respect to the magnetic flux passing through the magnetic body 10 and the gap 3. Rσw per unit length in the axial direction, where w is the average circumferential width of the magnetic body 10, h is the average radial height of the magnetic body 10, μ0 is the vacuum permeability, and μr is the relative permeability of the magnetic body 10. Is represented by the following equation (4).

  When the gap length is g and the circumferential dimension per stator slot is τ, Rδt per axial unit length is expressed by the following equation (5).

  Rδww is expressed by the following equation (6).

  However, if the magnetic flux passes through the dotted line shown in FIG. 2, the distance of the magnetic flux path is 2πh / 8 as a quarter of the circumference of the radius h / 2, and the interruption per unit length in the axial direction of the magnetic flux path. The area was h × 1.

  Rδwg is expressed by the following equation (7) as a distance g and a cross-sectional area h × 1 when w> 2 × h.

  Further, when w ≦ 2 × h, the cross-sectional area can be set to w / 2 × 1, which is expressed by the following formula (8).

  Further, assuming that the combined value of Rδww and Rδwg is Rδw, Rδw is expressed by the following equation (9).

  The combined value Rδ0 of the magnetoresistance per slot of Rδt and Rδw is expressed by the following equation (10).

  FIG. 3 is a diagram showing the main magnetic flux and the leakage magnetic flux of the induction motor in the present embodiment. FIG. 3 shows a case where the number of poles P is 2. When the number of stator slots is N1, and Rσw per pole is Rσ, when considering FIG. There are N1 / (2P) Rσw in series and two Rσw in parallel. Therefore, in this case, Rσ is expressed by the following equation (11).

  When the magnetic body 10 is installed between the adjacent convex portions 9, μr of the formula (4) is larger than 1, and when there is no magnetic body 10, μr of the formula (4) is 1. From the formulas (4) and (11), when the magnetic body 10 is installed between the adjacent convex portions 9, Rσ becomes smaller than when the magnetic body 10 is not provided. When Rσ becomes small, the magnetic flux leaking in the circumferential direction through the magnetic body 10 easily passes, and the magnetic flux that does not contribute to the generation of torque increases. That is, the current required to generate the desired torque increases.

  Assuming that Rδ0 per pole is Rδ, when considering per pole as shown in FIG. 3 divided vertically, there is one Rδ0 in series and N1 / P in parallel in the path of the main magnetic flux. Therefore, in this case, Rδ is expressed by the following equation (12).

  When the magnetic body 10 is installed between the adjacent convex portions 9, μr in the formula (6) is larger than 1, and when there is no magnetic body 10, the μr in the formula (6) is 1. From the formulas (6), (9), (10), and (12), when the magnetic body 10 is installed between the adjacent convex portions 9, Rδ is smaller than when there is no magnetic body 10. When Rδ decreases, the magnetic flux easily passes through the gap 3 in the radial direction, and a predetermined magnetic flux can be generated with a small current.

  By installing the magnetic body 10 between the adjacent convex portions 9, both Rσ and Rδ become small. In order to reduce the current and improve the power factor, Rσ should be large and Rδ should be small. Therefore, by installing the magnetic body 10 between the adjacent convex portions 9, Rσ is reduced, and the amount of decrease in current and the increase in Rδ is greater than the amount of increase in current, so that the magnetic body 10 is increased. If w, h, and μr are determined, by installing the magnetic body 10 between the adjacent convex portions 9, the current can be reduced and the power factor can be improved as compared with the case where the magnetic body 10 is not provided.

  FIG. 4 is an equivalent circuit diagram of the induction motor in the present embodiment. The impedance value obtained by dividing the rated voltage by the rated current is 1 p. u. It is said. When the no-load current is I0 and the rated current is I1, the excitation reactance Xm is expressed by the following equation (13).

  The leakage reactance Xmag with respect to the magnetic flux passing through the magnetic body 10 is expressed by the following equation (14).

  Xetc is a value obtained by subtracting Xmag from the sum of leakage reactances of the stator and the rotor. R1 is a primary resistance, R2 is a secondary resistance, and s is a slip. The value of R1 + R2 / s is 1p. u. It is determined to be.

  FIG. 5 is a diagram showing the relationship among the power factor, magnetic resistance, and permeability of the induction motor in this embodiment. In FIG. 5, the vertical axis represents the power factor and magnetoresistance ratio Rσ / Rδ, and the horizontal axis represents the relative permeability μr of the magnetic body 10. In FIG. 5, Rσ / Rδ in which the power factor calculated by the equations (13), (14), and FIG. 4 is equal to that in the case without the magnetic body 10 is derived. Rσ / Rδ that maximizes the power factor is also derived.

  As the relative permeability μr of the magnetic body 10 increases, Rσ decreases from the equations (4) and (11), and Rδ decreases from the equations (6), (9), (10), and (12). However, since Rσ / Rδ becomes smaller as shown in FIG. 5, Rσ has a larger influence on Rσ / Rδ than Rδ.

  Further, as the relative permeability μr of the magnetic body 10 increases, the power factor increases when the relative permeability μr of the magnetic body 10 is close to 1, and the relative permeability μr is sufficiently large as shown in FIG. Power factor is lowered. Therefore, when the relative permeability μr of the magnetic body 10 is close to 1, the magnetic body 10 is disposed between the adjacent convex portions 9, so that Rσ becomes smaller and Rδ becomes smaller than the increase in current, so that the current is increased. When the effect of reduction is large and the relative permeability μr is sufficiently large, Rδ is smaller than the amount by which Rσ is reduced and the current is increased by installing the magnetic body 10 between the adjacent convex portions 9. Therefore, the amount of current reduction is reduced.

  As the relative permeability μr of the magnetic body 10 increases, Rσ / Rδ decreases, whereas the power factor increases when the relative permeability μr is close to 1, and the relative permeability μr is sufficiently large. Therefore, the tendency of the change in power factor is different from Rσ / Rδ. That is, the w, h, and μr of the magnetic body 10 that reduces the current and improves the power factor as compared with the case without the magnetic body 10 by installing the magnetic body 10 between the adjacent convex portions 9 are It cannot be determined only by the ratio of the magnetic resistance of Rσ / Rδ of 2.

  FIG. 6 is a diagram showing the relationship between the current of the induction motor and the magnetic resistance in this embodiment. FIG. 6 is an approximate expression of Rσ / Rδ in which power factor is equal to the case where there is no magnetic body 10 in any case where I0 / I1 is different, according to the equations (4) to (14) and FIG. It is the result represented by. The range of Rσ / Rδ in which the power factor is higher than that without the magnetic body 10 is expressed by the following equation (15).

  Thus, by considering not only the ratio of the magnetic resistance of Rσ / Rδ but also the ratio of the currents I0 and I1, the power factor of the magnetic body 10 that can increase the power factor compared to the case without the magnetic body 10 can be obtained. , H, μr can be determined.

  Rσ / Rδ is expressed by the following equation (16) from equations (11) and (12) when considered per one pole obtained by dividing FIG. 3 vertically.

  Considering FIG. 3 per pole divided right and left, when Rσw per pole is Rσ, there are N1 / P Rσw in series and one in parallel on the path of the leakage flux. Therefore, in this case, Rσ is expressed by the following equation (17).

  Assuming that Rδ0 per pole is Rδ, considering that FIG. 3 is divided into left and right, there are two Rδ0s in series and N1 / (2P) in parallel in the path of the main magnetic flux. Therefore, in this case, Rδ is expressed by the following equation (18).

  Therefore, when FIG. 3 is considered per one pole divided right and left, Rσ / Rδ is expressed by the following equation (19) from equations (17) and (18).

  That is, from the equations (16) and (19), the same relationship can be derived for Rσ / Rδ even if it is considered per one pole obtained by dividing FIG.

  As described above, in this embodiment, the stator and the rotor are the rotary electric machines that face each other in the radial direction with a gap therebetween, and the stator protrudes in the radial direction from the core back and the core back. Thus, a stator core having a plurality of teeth provided in the circumferential direction and a stator winding wound around a stator slot formed between the adjacent teeth, the teeth project in the radial direction. Convex portions protruding further in the circumferential direction from the front end portion are provided on both sides in the circumferential direction, and a magnetic material is formed between adjacent convex portions. The circumferential component of the magnetic resistance of the magnetic material is Rσ, and the magnetic resistance of the gap When the radial component is Rδ, the no-load current is I0, and the rated current is I1, the following relationship is established.

  Thereby, it becomes possible to provide a rotating electrical machine and a rotating electrical machine system capable of increasing the power factor.

  FIG. 7 is a diagram showing the relationship among the current, magnetic resistance, and power factor of the induction motor in this embodiment. FIG. 7 shows the result of calculating Rσ / Rδ at which the power factor becomes maximum and the power factor at that time by (Equations 4) to (14) and FIG. 4 in arbitrary cases where I0 / I1 is different.

  In FIG. 7, the range in which Rσ / Rδ is larger than when the power factor is maximized is expressed by the following equation (21).

  When Rσ / Rδ increases, the relative permeability μr of the magnetic body 10 decreases as shown in FIG. In order to reduce the relative permeability μr, the magnetic body 10 contains a large amount of nonmagnetic electrical insulator. Therefore, the magnetic body 10 can ensure high electrical insulation and no electrical loss occurs in the magnetic body 10. Further, by including a large amount of non-magnetic electrical insulator in the magnetic body 10, the binding force with the magnetic powder or magnetic plate contained in the magnetic body 10 is increased, and the mechanical strength can be increased.

  In FIG. 7, the range in which Rσ / Rδ is smaller than when the power factor is maximum is expressed by the following equation (22).

  As Rσ / Rδ decreases, Xmag increases from equation (14). The primary current I1 during the starting operation is referred to as a starting current. From FIG. 4, if Xmag is large during the starting operation, the primary current I1 decreases and the starting current can be reduced. As Rσ / Rδ decreases, the relative permeability μr of the magnetic body 10 increases as shown in FIG. In order to increase the relative permeability μr, the magnetic body 10 may be composed of an electromagnetic steel sheet generally used for the stator core 6.

  As shown in FIG. 7, the effect of improving the power factor is larger when I0 / I1 is larger. Since I0 / I1 is 1 at the maximum, when I0 / I1 is large, that is, when the no-load current is as large as the rated current, the power factor is higher than that without the magnetic body 10 Rσ / The range of Rδ is expressed by the following equation (23) by substituting I0 / I1 = 1 into equation (15).

  As described above, in this embodiment, the stator and the rotor are the rotary electric machines that face each other in the radial direction with a gap therebetween, and the stator protrudes in the radial direction from the core back and the core back. Thus, a stator core having a plurality of teeth provided in the circumferential direction and a stator winding wound around a stator slot formed between the adjacent teeth, the teeth project in the radial direction. Convex portions protruding further in the circumferential direction from the front end portion are provided on both sides in the circumferential direction, and a magnetic material is formed between adjacent convex portions. The circumferential component of the magnetic resistance of the magnetic material is Rσ, and the magnetic resistance of the gap When the radial component is Rδ, the configuration has a relationship of Rσ / Rδ> 3.21.

  Thereby, it becomes possible to provide a rotating electrical machine and a rotating electrical machine system capable of increasing the power factor.

  In this embodiment, a rotating electrical machine system having a load facility driven by a rotating electrical machine using the rotating electrical machine described in Embodiments 1 to 4 and a rotating electrical machine system using the rotating electrical machine as a generator will be described.

  The present embodiment is a rotating electrical machine system in which any one of a compressor, a drill, a mill, and a fan is provided as a load facility. That is, as a rotating electrical machine system, a pump system that drives a compressor with a rotating electrical machine, a drilling system that drives a drill for drilling with the rotating electrical machine, a chip system that drives a mill for chips with a rotating electrical machine, a rotating electrical machine Build a fan system to drive the fan. Moreover, it is set as the generator system comprised with the rotary electric machine which converts the motive power of a turbine into electric power. The rotating electrical machines used in these rotating electrical machine systems are the rotating electrical machines according to the first to fourth embodiments. Thereby, since the rotary electric machine of Example 1 thru | or Example 4 has a high power factor, the electric current at the time of steady operation of a system can be made small, and it contributes to size reduction of a rotary electric machine system. In addition, since the rotating electrical machines according to the first to fourth embodiments have a small starting current, the current during the transient operation of the rotating electrical machine system can be reduced, which contributes to downsizing of the rotating electrical machine system.

  Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Rotor, 3 ... Gap, 4 ... Core back, 5 ... Teeth, 6 ... Stator core, 7 ... Stator slot, 8 ... Stator winding, 9 ... Convex part, 10 ... Magnetic Body 11 rotor core 12 rotor slot 13 rotor bar

Claims (10)

A rotating electrical machine in which a stator and a rotor face each other in a radial direction with a gap between them,
The stator is formed between an annular core back, a stator core having a plurality of teeth provided in the circumferential direction so as to protrude radially from the core back, and the adjacent teeth. The teeth are provided with stator windings wound in slots, and the teeth are provided with convex portions protruding in the circumferential direction from the tip portion protruding in the radial direction on both sides in the circumferential direction. The body is formed,
When the circumferential component of the magnetic resistance of the magnetic material is Rσ, the radial component of the magnetic resistance of the gap is Rδ, the no-load current is I0, and the rated current is I1, the following relationship is satisfied. Rotating electric machine.

The rotating electrical machine according to claim 1,
The rotating electrical machine, wherein the magnetic body has a relationship of the following formula.

The rotating electrical machine according to claim 1,
The rotating electrical machine, wherein the magnetic body has a relationship of the following formula.

The rotating electrical machine according to claim 1,
The rotating electric machine according to claim 1, wherein the no-load current is approximately equal to the rated current. A rotating electrical machine in which a stator and a rotor face each other in a radial direction with a gap between them,
The stator is formed between an annular core back, a stator core having a plurality of teeth provided in the circumferential direction so as to protrude radially from the core back, and the adjacent teeth. The teeth are provided with stator windings wound in slots, and the teeth are provided with convex portions protruding in the circumferential direction from the tip portion protruding in the radial direction on both sides in the circumferential direction. The body is formed,
A rotating electrical machine having a relationship represented by the following equation, where Rσ is a circumferential component of the magnetic resistance of the magnetic body and Rδ is a radial component of the magnetic resistance of the gap.

The rotating electrical machine according to claim 1,
A rotating electrical machine characterized in that Rσ / Rδ is determined so that the power factor is higher than when there is no magnetic material. The rotating electrical machine according to claim 2,
The rotating electrical machine according to claim 1, wherein the magnetic body is composed of magnetic powder or a magnetic plate and a nonmagnetic insulator. The rotating electrical machine according to claim 3,
The rotating electrical machine characterized in that the magnetic body is made of an electromagnetic steel plate.   It has a rotary electric machine of any one of Claim 1 to 5, it has a load installation driven with this rotary electric machine, and this load installation is either a compressor, a drill, a mill, or a fan. A rotating electrical machine system that is characterized.   A rotating electrical machine system comprising the rotating electrical machine according to any one of claims 1 to 5, wherein the rotating electrical machine is used as a generator, and the rotating electrical machine converts power of a turbine into electric power. .

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