JPH1084654A - Induction rotor of non-bearing rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction rotor of a non-bearing rotating machine which eliminates the effect of an induced current generated by a position control magnetic field and enables stable levitated position control, without impeding generation of a drive current by a rotating magnetic field. SOLUTION: This rotating machine has a cylinder rotor and a rotation driving force given to the rotor and a radial levitated position of the rotor are controlled simultaneously by generating M poles being a rotor driving magnetic field and N poles being M ± 2 poles in a gap between a stator and the rotor and by superposing the magnetic field distribution of the N poles on the magnetic field distribution of the M poles, by a plurality of windings wound on the stator. In this case, the rotor wherein ring current paths 15 which are present on a plane containing the axis of rotation and do not intersect the axis of rotation are arranged in a plurality in the circumferential direction is provided. A current path 13 is cut at one place, a voltage induced to the ring current paths 15 by a position control magnetic flux distribution is thereby canceled, the ring current paths 15 in a plurality are connected so that a current by the voltage may not flow and thereby current paths 15, 20, 15 and 21 in one circuit are constructed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearingless rotating machine having both an electric motor function for driving a rotating body to rotate and a magnetic bearing function for controlling a magnetic levitation of the rotating body. The present invention relates to a structure of an induction type rotor provided.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open Nos. 2-193,546, 6-141512, 6-133493, etc. disclose a cylindrical rotor in a cylindrical stator.
There is disclosed a bearingless rotating machine in which an excitation circuit is formed in a stator, where a rotational force is applied to a rotor and magnetically levitated and held at a predetermined position to apply a position control force. this is,
The stator is provided with a winding for rotation driving and a winding for control, and a three-phase alternating current is applied to each to form a rotating magnetic field having a different number of poles in a predetermined relationship, thereby forming a rotating shaft of the cylindrical rotor. The magnetic attraction in the radial direction is distributed on the vertical plane.

Thus, the rotor is magnetically attracted,
In addition to functioning as an electric motor that applies a rotational force to the rotor, it can function as a magnetic bearing capable of supporting the stator in a non-contact floating manner by controlling its floating position and attitude. For this reason, an electromagnet yoke portion and a winding corresponding to a magnetic bearing, which have been conventionally required, are not required, and the shaft length of the rotating machine can be shortened, and the limitation of high-speed rotation from shaft vibration can be reduced. Further, the size and weight of the rotating machine can be reduced. In addition, the operation equivalent to a magnetic bearing can be performed by a synergistic effect of a magnetic field generated by the current of the control winding and the current of the drive winding, so that the control force can be reduced with a much smaller current than a conventional magnetic bearing. , And significant energy savings are possible.

In such a bearingless rotating machine, an M-pole rotating magnetic field and an N-pole rotating magnetic field are generated by passing a current through a winding of a stator. Hereinafter, the M-pole rotating magnetic field is referred to as a driving magnetic field, and the N-pole rotating magnetic field is referred to as a position control magnetic field. The driving magnetic field is used to apply a rotational driving force to a rotor like a normal electric motor.
Since the position control magnetic field is superimposed on the driving magnetic field, it is possible to apply a radial force to the rotor, so that the radial position of the rotor can be freely adjusted. Since M and N have a relationship of N = M ± 2, the flying position control can be performed.

[0005] An induction rotor is one of the systems in which an induced current is generated in a secondary conductor of the rotor by a rotating magnetic field generated by the stator to apply a rotational driving force. There are various types of induction type rotors, and a typical example is a cage type rotor. This consists of arranging a number of low-resistance metal conductor rods (secondary conductors) on the rotor as current paths substantially parallel to the rotation axis, and fixing each metal conductor rod to a low-resistance metal conductor ring (end ring) at both ends. It was done. The number of magnetic flux linkages in the rotor secondary conductor fluctuates due to the rotating magnetic field formed by the stator winding, and an induced voltage is generated in the rotor secondary conductor due to the electromagnetic induction phenomenon, so that an induced current flows. The Lorentz force is generated by the interaction between the magnetic flux interlinked by the rotor and the induced current on the rotor, and a rotational driving force is generated in the induction rotor.

[0006]

In a bearingless rotating machine, since an M-pole distributed magnetic field and an N-pole distributed magnetic field are mixed, when an ordinary cage-type induction rotor is used, the rotor current path is reduced. A current induced by both magnetic fields flows through the (conductor bar). Since the rotating magnetic field having the M pole distribution applies a rotational driving force to the rotor, in principle, it cannot be realized as an induction motor unless an induced current flows. On the other hand, when an induced current due to the N-pole distributed position control magnetic field flows through the rotor current path, in addition to the magnetic flux generated by the stator winding, a magnetic flux generated by the rotor current as a disturbance is generated. The magnetic flux is not determined only by the magnetic fluxes of the M and N poles formed by the winding current of the stator, and the radial force becomes unstable, so that stable floating position control of the rotor cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not hinder generation of a driving current by a rotating magnetic field, eliminates the influence of an induced current by a position control magnetic field, and enables stable flying position control. An object of the present invention is to provide an induction rotor of a bearing rotating machine.

[0008]

The induction rotor of the bearingless rotating machine of the present invention is a rotating machine having a cylindrical rotor,
A plurality of windings wound around the stator generate a magnetic field distribution of an M pole which is a rotor driving magnetic field in an air gap between the stator and the rotor and an N pole which is M ± 2 poles in the magnetic field distribution. By superimposing, in a rotating machine that simultaneously controls the rotational driving force applied to the rotor and the radial floating position of the rotor, an annular current path that is on a plane including the rotation axis and does not intersect with the rotation axis is formed. A plurality of rotors arranged in the circumferential direction are provided, one portion of the current path is cut, and the voltage induced in the annular current path by the position control magnetic flux distribution is canceled, so that the current does not flow. A plurality of annular current paths are connected to form one current path.

Further, in the rotor, if n is an integer in order to connect each current path so as to cancel the voltage induced in each annular current path by the flying position control magnetic field, a certain annular current path and its Two current paths of the current path at a rotation angle of n × 360 ° / N from the current path are connected so as to form one ring, and when n is an even number, the radius of the ring is used. When n is an odd number, the two parallel current paths parallel to the rotation axis are located so that the two current paths parallel to the rotation axis positioned outside in the direction are opposite to each other. The current paths are connected so as to be in the same direction.

[0010] Also, the present invention is characterized in that one current path connecting the two rings is connected to form a single current path.

Further, in the induction rotor of the rotary machine, the axial current length of the rotor is shortened by connecting the annular current path inside the rotor.

According to the configuration of the present invention described above, the driving current flows through the current path of the rotor generated by the magnetic flux generated by the driving magnetic field, and the current path of the rotor is controlled by the induced voltage generated by the magnetic flux generated by the position control magnetic field. To prevent the generation of induced current. Therefore, since only the drive current by the drive magnetic field flows through the current path of the rotor, the same torque as that of a normal cage rotor is generated by this Lorentzka, and the rotor is rotationally driven. On the other hand, since the induced current due to the position control magnetic field does not flow, the rotation drive magnetic field of M pole generated by the stator and the position control magnetic field of M ± 2 pole (N pole) are:
It is possible to supply a control magnetic flux that levitates and supports the rotor without being affected by the rotor current. As a result, stable floating position control can be performed even in a bearingless rotating machine having an induction rotor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of an induction rotor according to one embodiment of the present invention. In this figure, only a portion corresponding to one annular current path is shown. The rotor 11 is made of a laminated silicon steel sheet, and a large number of low-resistance metal conductor rods 12 and 13 constituting an annular current path 15 are embedded in the laminated silicon steel sheet at a uniform pitch in a circumferential direction, and a deformed cage is formed. It has a type structure. Since the rotor 11 is entirely made of a silicon steel sheet having a high magnetic permeability, the driving magnetic field of the M pole and the N pole (= M ± 2
(Polar) easily acts as a target material of a magnetic bearing, easily receiving a magnetic attraction in the radial direction due to the superposition of the position control magnetic field. In this embodiment, the stator will be described with a driving magnetic field of four poles and a position control magnetic field of two poles.

The rotor is composed of double conductor rods 12 inside and outside.
The inner and outer conductor rods 13 and 12 in the same radial direction are connected to each other by conductor short-circuit members 14. To prevent current from flowing through the rotor 11,
Each conductor bar and the rotor are insulated. Since the inner conductor bar 13 has one cut portion in the middle, the current path is “C” shaped as it is, so that no current is induced. In an actual rotor, a large number of such current paths are provided similarly at equal intervals in the circumferential direction, similarly to the cage rotor.

As shown in FIG. 2, this current path is connected to current paths 15 and 15 which are radially opposed to each other, and connection conductors (connection members) 20 and 21 are formed so as to form one ring (closed loop) at the cut portion.
Connect with. At this time, the conductor 21 connects the lower cut surface 13A of the current path inner conductor bar and the upper cut surface 13D of the current path inner conductor bar facing in the radial direction. Similarly, the upper side 13B and the lower side 13C of the inner conductor rods 13, 13 are connected by conductors 20 between opposing current paths. The current path shown in FIG. 2 is one of a plurality of current paths. In the current path having this shape, a magnetic flux generated by the two-pole position control magnetic field generates an induced voltage in the opposite direction on the opposing conductor rods 12, 12.
Since this is connected so as to cancel, no induced current due to the position control magnetic field flows. On the other hand, an induced voltage in the same direction is generated in the opposing conductor rods 12 by a magnetic flux generated by the four-pole driving magnetic field, and the conductor rods 12 are connected so as to apply the induced voltage. .

The outer conductor rod is located on the rotor surface, and the magnetic flux flowing into the rotor is uniform in the axial direction. The magnetic flux density exerted on the rotor by the driving magnetic field is represented by B ₄ , and the magnetic flux density exerted by the position control magnetic field on the rotor is represented by B ₄ . and B _2. When the rotation angle is θ on fixed coordinates,

(Equation 1)

(Equation 2) And the magnetic flux flowing into the rotor. Here, t is time, ω
₄ is the relative rotational angular velocity of the quadrupole driving magnetic field to the rotor, ω
₂ indicates the relative rotational angular velocity of the bipolar position control magnetic field with respect to the rotor, and _BP4 and _BP2 indicate the drive magnetic field and the amplitude of the magnetic flux generated by the position control magnetic field.

The quadrupole magnetic flux Φ ₄ linked to the C-shaped annular current path 15 of FIG.

(Equation 3) Here, R represents the rotor radius, and l represents the axial length of the rotor current. The voltage E ₄ induced in the C-type current path is

(Equation 4) It is.

Similarly, the voltage E ₄ ′ induced in the C-shaped annular current path 15 on the opposite side of the angle θ in the radial direction, that is, at the angle θ + π, is

(Equation 5) It is.

When the current paths at θ and θ + π are connected as shown in FIG. 2, the voltage induced in this current ring is

(Equation 6) Then, a current uniquely determined from the voltage represented by this equation and the impedance of the current path flows.

On the other hand, the two-pole magnetic flux Φ ₂ linked to the C-shaped annular current path 15 shown in FIG.

(Equation 7) And the voltage induced in this current path is

(Equation 8) It is.

Similarly, the voltage E ₄ ′ induced on the C-type current path at the opposite side of the angle θ, ie, at the angle θ + π, is

(Equation 9) It is.

When the current paths at θ and θ + π are connected as shown in FIG. 2, the voltage induced in this closed loop becomes E ₂ + E ₂ ′ = 0, and no induced voltage is generated. That is, no current flows in the current path on the rotor due to the bipolar position control magnetic field.

When the current paths shown in FIG. 2 are arranged in the circumferential direction of the rotor, the current paths intersect at the center of the rotor, so that the structure at this portion becomes complicated. In order to avoid this problem, if the current paths are expanded in the direction of the rotation axis to connect the current paths, the length of the rotor in the direction of the rotation axis becomes longer.

FIGS. 3 and 4 show a method for simply connecting the current paths in the inner peripheral portion of the rotor. In FIG. 3, the current path is obtained by winding one and a half turns on a plane including the rotation axis. That is,
Two inner conductor rods 13 for one outer conductor rod 12,
13 are connected by short-circuit members 14 and 14. In this embodiment, eight outer conductor rods 12 connecting two inner conductor rods are laid at equal intervals in the circumferential direction. For this reason, the inner conductor rod 13
Are arranged at equal intervals in the circumferential direction.

Four short-circuit rings 23 shown in FIG. 4 are used and laid so as to pass the inner conductor bar 13 between the short-circuit ring 23 and the rotation shaft inside the rotor. The current paths facing each other are connected by using two short-circuit rings 23. Holes 2 arranged in the circumferential direction of the short-circuit ring
The hole diameter of the small hole 25 among the holes 5 and 26 is the same as the outer diameter of the conductor rod 13, and the electrical connection is made by this portion. A conductor rod passes through the large hole 26, but there is no electrical contact because the hole diameter is larger than the conductor rod diameter. An insulator is sandwiched between the short-circuit rings 23 so that electrical contact does not occur. Also, insulation is required between the rotor 11 and the short-circuit ring 23. In the actual manufacturing process, it is necessary to fix the short-circuit ring 23 before fixing the short-circuit member 14 connecting the inner conductor bar and the outer conductor bar.

As is clear from the above description, the connection between the short-circuit ring 23 and the inner conductor bar 13 enables the same connection as the connection by the connection conductors 20 and 21 shown in FIG.
In the present embodiment, the connection between the annular current paths 15, 15 can be made regularly using the inner peripheral portion of the rotor 11, so that the connection structure is made compact and the connection work is facilitated. be able to.

FIG. 5 shows the driving magnetic field of M poles and N = M ±
2 illustrates a method of connecting each current path for canceling a voltage induced in each annular current path when a position control magnetic field of No. 2 is superimposed.
If n is an integer, a certain annular current path and two current paths 15A, 15A at a rotation angle nX360 ° / N from the current path.
B is connected so as to form one ring (closed loop). As an example of the connection method, when n is an even number, as shown in (B), the connection is performed such that currents in opposite directions flow through the conductor rods 12, 12 located radially outside the annular current path. On the other hand, when n is an odd number, as shown in (C), the directions of the currents flowing in the two conductor rods 12 and 12 parallel to the rotation axis located radially outside the annular current path are in the same direction. Connections as shown.

The connection between the certain annular current path 15A and the annular current path 15B located at the rotation angle nπ (n is an odd number) of the magnetic angle with respect to the number N of poles of the position control magnetic field is shown in FIG. By doing so, the conductor bars 12 on the outer periphery are connected so that current flows in the same direction. In each of the conductor rods 12, the magnetic flux cut by the annular current path has a magnetic angle of nπ (n is an odd number), so that an induced voltage in the opposite direction is generated. As a result, the induced voltages cancel each other out, so that the induced current generated by the position control magnetic field does not flow through the rotor, and the problem of the instability of the rotor floating position control due to this current can be prevented.

If n is an even number, the annular current path 15
A and 15B are nπ (n is an even number) for the position control magnetic field.
It is located at the rotation angle of. In this case, as shown in (B), the annular current paths 15A and 15B are connected in parallel, so that current paths are formed in the outer conductor rods 12 and 12 so that currents flow in opposite directions. Therefore, as for the induced voltage generated by interlinking with the position control magnetic flux, since the position control magnetic field has the same polarity, an induced voltage in the same direction is generated in each of the conductor rods 12. As described above, since the current paths are connected to the conductor rods 12 and 12 so that current flows in the opposite directions, the induced voltages due to the position control magnetic fields become opposite to each other and cancel each other. Therefore, no current flows through the rotor due to the position control magnetic field of the N pole, and the problem of instability due to the position control magnetic field is solved.

FIG. 6 shows the direction of the voltage induced in the above-mentioned current path when the driving magnetic field has six poles and the position control magnetic field has eight poles. The directions of the induced voltages generated by the six-pole driving magnetic field act in directions to be applied to each other as shown in FIG.
As a result, a drive current flows, and a Lorentz force is generated, and a rotational torque is generated in the same manner as a normal induction motor. And
As shown in (B), for the 8-pole position control magnetic field, an induced voltage is formed in the direction indicated by the arrow. The induced voltages cancel each other out and become zero in the closed loop. For this reason, even if the secondary conductor rod of the rotor is linked to the position control magnetic flux, no induced current is generated, and the problem of the instability of the rotor associated therewith does not occur.

FIG. 6C shows an example in which the four annular current paths 15A and 15B shown in FIGS. 6A and 6B are connected to one current path. As shown in the drawing, the induced currents due to the six-pole driving magnetic field generated in the four conductor rods 12 act in a direction to add each other, and the induced currents due to the eight-pole position control magnetic field act in a direction to cancel each other out. It becomes zero as a closed loop. By thus forming the current path in one closed loop, the rotor winding can be simplified.

Although the above description has been made with reference to an example of a bearingless motor, it goes without saying that the gist of the present invention can be similarly applied to a generator.

[0034]

As described above, according to the present invention, in the induction rotor of the bearingless rotating machine, the current path parallel to the rotating shaft in the stator is made double in the radial direction, and the position control magnetic flux is formed. It is possible to form a current path that does not generate an induced current generated by interlinking with the rotor. When this rotor is applied to a bearingless rotating machine, no magnetic flux is generated by the rotor secondary current of the position control magnetic field, so that stable rotor levitation control can be achieved. Along with this, it becomes easy to control the radial position of the rotor by the position control current, and it can be expected that the number of parts is reduced, the reliability is improved, and the cost is significantly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an annular current path arranged in a rotor according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing two annular current paths connected so that induced voltages generated by a position control magnetic field cancel each other.

FIG. 3 is an explanatory view showing a modification of the annular current path shown in FIG. 1;

FIG. 4 is an explanatory view of a short-circuit ring.

FIG. 5 (A) is an explanatory diagram showing the relationship between the rotation angles of two annular current paths that are connected to each other to form one closed loop,
(B) Connection diagram when n is an even number, and (C) Connection diagram when n is an odd number.

6A is an explanatory diagram showing the direction of an induced voltage by a 6-pole driving magnetic field, FIG. 6B is an explanatory diagram showing the direction of an induced voltage by an 8-pole position control magnetic field, and FIG. FIG. 4 is an explanatory diagram showing an example of connection in one closed loop.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 rotor 12 radially outer conductor rod 13 radially inner conductor rod 14 short-circuit material 15 annular current path 20, 21 connection member

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Kazuki Sato 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Inside Ebara Research Institute, Ltd.

Claims (4)

[Claims] 1. A rotating machine having a cylindrical rotor, wherein a plurality of windings wound around a stator provide an M pole as a rotor driving magnetic field in a gap between the stator and the rotor. By generating and superimposing a magnetic field distribution of N poles of M ± 2 poles on the distribution, a rotating machine for simultaneously controlling a rotational driving force applied to the rotor and a radial floating position of the rotor, A rotor in which a plurality of annular current paths that are on a plane that does not intersect with the rotation axis are arranged in the circumferential direction, cut one portion of the current path, and are guided to the annular current path by a position control magnetic flux distribution. Wherein the plurality of annular current paths are connected to each other so as to cancel a voltage that is generated and a current does not flow, thereby forming a single current path. 2. The rotor according to claim 1, wherein n is an integer in order to connect each current path so as to cancel a voltage induced in each annular current path by the flying position control magnetic field. From the annular current path and its current path, the rotation angle n × 36
The two current paths of the current path at 0 ° / N are connected so as to form a single ring, and when n is an even number, the rotation axis positioned radially outside the ring when n is an even number. When n is an odd number, the directions of the two current paths parallel to the rotation axis located radially outward of the annular current path are the same so that the directions of the two current paths parallel to the current path are opposite to each other. An induction rotor of a bearingless rotating machine characterized by being tied so as to be in the same direction. 3. The induction rotor for a bearingless rotating machine according to claim 2, wherein a single current path connecting the two rings is connected to form a single current path. 4. The induction type rotor of the rotary machine,
By connecting the annular current paths inside the rotor,
The induction rotor of a bearingless rotating machine according to any one of claims 1 to 3, wherein an axial length of the rotor is reduced.