JPH10201170A - Bearingless electric rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform orthogonal biaxial control of a rotor in the radial direction and rotary driving force control thereof by passing a flux generated through magnetomotive force of a winding wound around the cylindrical surface on the inside of a stator through the cylindrical surface of the rotor and the vertical cross-section vertical of a rotary shaft. SOLUTION: Two rotors 11, 12 are arranged continuously in the direction of rotary shaft and connected through a magnetic material 13A. The magnetic material 13A serves as a magnetic path coupling the two rotors 11, 12. Flux passing through the rotors 11, 12 depends on the acting face of the rotor and the magnetic material 13A. A flux entering from (leaving to) a stator 10 partially passes through the magnetic material 13A to form a closed magnetic path passing through the rotors 11, 12. The stator 10 is provided with two sets of three-phase winding corresponding to the rotor, total six phase windings. These windings are fed with currents of same frequency and different amplitude having phase shift of 120 deg. so that a tetra-axial radial floating position control force, as well as a rotary driving force, acts on the rotor.

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 such as an electric motor or a generator suitable for high-speed or ultra-high-speed operation, which has a function of controlling a position of a rotor in a radial floating direction by an electromagnetic force.

[0002]

2. Description of the Related Art As a prior art, a cylindrical rotor is incorporated in a cylindrical stator, and an exciting circuit is formed in the stator. 2. Description of the Related Art There is known a bearingless rotating machine in which a rotation control magnetic field is superimposed to apply a rotational force to a rotor and at the same time to apply a position control force for floating and holding at a predetermined position. In this method, a stator is provided with a winding for rotation driving and a winding for flying position control, and a three-phase alternating current is applied to each of them to form a rotating magnetic field having a different number of poles, thereby forming a rotating rotor. The magnetic effect is exerted on the section perpendicular to the axis. Thereby, the inner circumferential surface of the stator magnetically attracts the rotor and controls its floating position,
In addition to having a rotation positioning function capable of supporting the stator in a non-contact manner, a rotational force can be applied to the rotor.

[0003] The stator winding used in the bearingless rotating machine requires a position control winding in addition to a normal rotation driving winding for applying a rotating machine output to the rotor. Therefore, in the bearingless rotating machine having this configuration, the number of windings wound around the stator increases by the amount corresponding to the position control winding, and the configuration becomes complicated. Further, since the number of windings has increased, complicated control circuits such as a power amplifier for controlling the winding current are required.

In the prior art apparatus, a plurality of independent single-pole windings are used to generate the same magnetic flux distribution in the air gap between the rotor and the stator as in the bearingless rotating machine having the above-described configuration, and the same operation and effect are obtained. Have gained. In this type of bearingless rotating machine, a single-pole winding is required to be at least twice as large as the greater of the number of poles of the position control magnetomotive force and the number of poles of the rotation drive control magnetomotive force. For example, when the number of poles of the position control magnetomotive force is 4 and the number of poles of the rotation drive control magnetomotive force is 6, 12 or more single-pole windings are required.

[0005] Therefore, not only is the winding of the winding around the stator complicated, but also the number of lead wires of the winding is increased, and the connection is not easy. In addition, the increase in the number of windings increases the number of power amplifiers for controlling winding currents and associated control circuits.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to simplify the stator winding, control the rotational driving of the rotor, and control the flying position. It is an object of the present invention to provide a bearingless rotating machine based on a new principle.

[0007]

SUMMARY OF THE INVENTION A bearingless rotating machine according to the present invention is a rotating machine having a cylindrical rotor on the inner periphery of a cylindrical stator. The magnetic flux generated by the magnetomotive force passes through a cross section perpendicular to the rotor cylindrical surface and the rotation axis, thereby controlling the position of two axes orthogonal to each other in the radial direction of the rotor and controlling the rotational driving force of the rotor. And

Further, the two rotating machines are arranged in the direction of the rotating shaft, and the rotors of the two rotating machines are connected with a magnetic material so that the rotating shafts are the same. The magnetic flux generated by the magnetomotive force of the winding wound on the cylindrical surface passes through one of the rotor cylindrical surfaces of the rotating machine, the magnetic material, and the other rotor cylindrical surface of the rotating machine, and thereby, It is characterized in that, for each rotor, position control is performed on two axes orthogonal to each other in the radial direction, and rotational driving force of the rotor is controlled.

Further, the magnetomotive force generated by the winding wound on the cylindrical surface inside the stator, the magnetomotive force distribution when the rotor is rotated by half with respect to the rotation axis of the rotor, The present invention is characterized in that the windings have three or more phases in which the magnetomotive force distribution when the direction of current flow is reversed is not the same.

According to a third aspect of the present invention, when the windings have three phases, the winding distribution of each winding has a phase difference of 120 °.

Also, in a bearingless rotating machine in which two rotors are joined by a magnetic material so that the rotating shafts are the same,
A six-phase power amplifier is used to control the current flowing through the six windings.

Further, in the bearingless rotating machine according to claim 5, one of the terminals of the six windings is connected to the power amplifier by six current paths, and all the other six terminals of the winding terminals are connected. It is characterized by common connection.

According to the present invention described above, the magnetic flux generated by the magnetomotive force of the stator winding passes through the rotor circumferential surface and a cross section perpendicular to the rotating shaft, thereby reducing the amount of magnetic flux along the circumferential direction of the rotor. Can be unbalanced. Thus, three phases of monopolar windings are arranged along the circumferential direction, and currents having a constant frequency and a phase difference of 120 ° are supplied independently, thereby applying a radial force to the rotor and rotating the rotor. Can be driven. Therefore, the configuration of the stator winding for controlling the rotational driving force and the radial position of the rotor has been simplified. That is,
By reducing the number of phases of the winding wound on the stator, the operation of winding the stator on the winding is simplified, and at the same time, the rotor is rotationally driven while the configuration of the winding current amplifier is minimized. In addition, the flying position control can be performed.

[0014]

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

FIG. 1 illustrates the principle of operation of a bearingless rotating machine according to the present invention. (A) shows the cylindrical rotor 11, and its cylindrical outer peripheral surface is hereinafter referred to as an operation surface. As shown in (b), the working surface of the cylindrical rotor 11 faces the inner peripheral surface of the cylindrical stator 10 arranged coaxially via a slight gap. In order to make the magnetic flux distribution along the circumferential direction of the air gap asymmetric, a magnetic path is actively provided to guide the magnetic flux so that the magnetic flux enters and exits from other than the working surface. The magnetic flux 生 じ る generated by the current (magnetomotive force) flowing through the winding provided in the cylindrical inner peripheral surface of the stator is generated by connecting the magnetic material 13A to the section perpendicular to the rotation axis. And a section perpendicular to the rotation axis. Therefore, the magnetomotive force is reduced by one-turn along the circumferential direction of the three-phase winding.
By displacing them by 20 ° and supplying currents having the same frequency and a different phase with a phase shift of 120 ° to each other, a rotational driving force is applied to the rotor as shown in FIG. A radial force can be applied.

FIG. 2 shows a structure in which two such rotors 11 and 12 are connected in the direction of the rotation axis, and the two are connected by a magnetic material 13A. The magnetic material 13A includes two rotors 1
It becomes a magnetic path connecting 1 and 12. The magnetic flux entering and exiting the rotors 11 and 12 is from the rotor working surface and the magnetic material 13A.
Part of the magnetic flux flowing in (out) from the stator passes through the magnetic material 13A, and a closed magnetic path is formed via the rotors 11 and 12. The stator is provided with two sets of three-phase windings corresponding to the respective rotors, for a total of six-phase windings.
By supplying the above-mentioned current to this winding, (c)
As shown in FIG. 7, the four-axis radial floating position control force can be applied to the rotor together with the rotational driving force.

FIG. 3 is a sectional view taken along the rotating shaft of the bearingless rotating machine having the function of controlling the position of the four axes in the radial direction according to the present invention. The two rotors 11 and 12 are connected by a rotating shaft 13, and a magnetic material is used to use the connection 13A as a magnetic path. Displacement sensors 14 and 15 for detecting the position of the rotor are fixed to the casing 17 of the rotating machine at both ends of the rotating shaft 13. Also, when the position of the rotor cannot be controlled due to an accident such as a system failure or a power failure, an emergency bearing 18 for supporting the rotating shaft 13 is provided.
19 is fixed to the casing 17. In the normal floating state of the rotating body, the emergency bearings 18 and 19 and the rotating shaft 1
3 has an interval enough not to touch. A detector 20 for detecting the rotation angle of the rotor is provided at the center of the rotation shaft 13.
Is arranged.

In the present embodiment, the rotors 11 and 12 are of a permanent magnet synchronous type having a permanent magnet attached to the surface, but are of an induction type or a reluctance type which actively utilize armature reaction. The same can be applied to Stator 2
Reference numerals 1 and 22 are formed of a magnetic material, and one stator is provided with a three-phase winding. Stators 21 and 2
A coil end 23 protrudes from the end of the second end.

FIG. 4 schematically shows the distribution of windings wound around the stator.
Shown in U-, V-, and W-phase three-phase windings are locally wound around the stator such that the magnetomotive force generated by the windings in the air gap is monopolar. Although the winding in the figure is a concentrated winding, the following description of the operating principle assumes a distributed winding and assumes a sinusoidal magnetomotive force distribution.

In the following, one of the rotor 11 and the stator 21
L, the other rotor 12 and stator 22
Is called R, and subscripts L and R are added to distinguish the state variable quantities. The magnetomotive force distribution generated by the stator winding unit current of the rotating machine L is given by AuL = N ｛cos θ + 1｝ AvL = N ｛cos (θ + 4π / 3) +1｝ AwL = N ｛cos (θ + 2π / 3) +1｝ R is also defined as AuR = N {cosθ + 1} AvR = N {cos (θ + 4π / 3) +1} AwR = N {cos (θ + 2π / 3) +1}.

The current flowing through each phase of the rotating machine L is represented by Iu
L, IvL, IwL, and the current flowing through each phase of the rotating machine R are represented by IuR,
IvR and IwR. The rotor is magnetized by a permanent magnet, and its magnetic flux density distribution is given by Br (θ, ωt) = Br cos (θ−ωt) where ωt: rotor rotation angle.

When no permanent magnet is laid on the rotor, the magnetic flux density formed by the magnetomotive force AuL is expressed by equation (1), ignoring the iron core magnetic resistance.

(Equation 1) g: air gap length between rotor and stator μ ₀ : magnetic permeability in vacuum

The magnetic flux density at an arbitrary angle θ is expressed by the following equation. B (θ, ωt) = Br (θ, ωt) + BuL (θ) + BvL
(Θ) + BwL (θ) The magnetic energy δW stored at the minute rotation angle δθ is given by the following equation (2).

(Equation 2) l: Rotor axis direction length R: Rotor radius

The total magnetic energy W stored in this gap
Is calculated by equation (3).

(Equation 3) The torque τ acting between the stator and the rotor is expressed by the equation (4) on one side of the motor.

(Equation 4) For two motors L and R

(Equation 5) It is represented by

FIG. 5 shows a state in which a non-salient pole rotor is eccentrically located in a stator having a smooth inner surface. The length of the gap when the rotor is positioned in the center of the stator and g _0. The eccentric distance of the rotor is α in the α-axis direction and β in the β-axis direction. (B) is an enlarged view near the center. Assuming that the air gap length is sufficiently small compared to the rotor radius, the air gap length g can be expressed as g = g ₀ −α cos φ−β sin φ due to the eccentricity of the rotor.

Further, if the eccentricity of the rotor is sufficiently smaller than g ₀ , that is, | α | ≪g ₀ , | β | ≪g ₀ , the permeance P per unit area becomes P (φ ) = (Μ ₀ / g ₀ ) (1−α cos φ / g ₀ −β sin φ /
g ₀ ). Since the magnetic flux density distribution B formed by the magnetomotive force A in the air gap is represented by B = A / P, the total magnetic flux density in the air gap becomes ΣB = Br + Bu + Bv + Bw.

The equation for the total magnetic energy W in this gap is:

(Equation 6) , The force Fα in the α direction and the force Fβ in the β direction are

(Equation 7)

(Equation 8) It is.

From the above, the control forces FαL, FβL, FαR, FβR acting on the rotary machines L, R are as follows.

(Equation 9)

The condition that no magnetic flux enters or exits from other than the facing surface between the rotor and the stator is as follows.

(Equation 10) By simplifying this, IuL + IvL + IwL + IuR + IvR + IwR = 0 (5)

The three-phase current I3L = (IUL, IVL, IWL)
If the matrix for converting the two-phase current I2L = (IαL, IβL, IOL) is C ₃₂ , then I 2 = C _{32 I} 3

[Equation 11]

Further, when a matrix for transforming the two-phase currents into three-phase current and _{C 23 I3 = C 23 I2 (} 6)

(Equation 12) I3R = (IUR, IVR, IWR), I2L (IαR, IβR,
The same applies to IOR).

The torque τ, the control forces FαL, FβL, FαR,
Expressing FβR etc. by two-phase current

(Equation 13)

If the above equation is represented by variables k1 to k6 consisting only of the state variables of the rotating machine,

[Equation 14] (7)

From the above equation, the two-phase current of the rotating machine is as follows.

(Equation 15) ... (8)

FIG. 4 shows a control block diagram. Since the two rotors 11 and 12 are fixed to the same rotating shaft 13 via the magnetic material 13A, they rotate at the same speed. In the configuration shown in this figure, 4-axis floating position control and rotation output control are possible.
For this control, a rotor displacement detector for detecting the radial position of the rotor and a rotation angle detector 20 for detecting the rotor rotation angle for four axes 14 and 15 are used in the bearingless rotating machine shown in FIG. Provided. The displacement detector 14.15 is the rotation axis 1
3 are attached to both ends in the orthogonal direction, and output radial displacement signals αL, βL, αR, βR. α and β are on a section perpendicular to the rotation axis, and have a positional relationship orthogonal to the rotation axis.

The displacement detector is not a separate type as shown in the figure, but may use a winding wound around a stator. That is, by using as an inductance type displacement detector for detecting the position and posture of the rotor from a change in the inductance of the winding, a separate type displacement detector can be dispensed with. Thereby, the space for the displacement detector can be reduced.

The rotor radial position signals αL, βL, αR,
βR and the target command value ^{αL *, βL *, αR *} , compared with βR ^*,
The deviation is calculated by the position controller 30, and the control force command values FαL ^* , FβL ^* , FαR with respect to the rotor radial position are calculated.
^* , FβR ^* .

The system includes a rotation angle detector 20 for detecting the rotation angle of the rotor, a rotation angle calculator 31 for calculating the rotation angle ωt from the signals obtained therefrom, and a rotation angle calculator for calculating the rotation speed ω of the rotor. The speed calculator 32 is provided. The rotation angle signal ωt is calculated by the calculators 1 to 6 based on the equation (7), and the coefficients k1, k2, k3, k4, k5, k6
Get. The obtained rotation speed signal ω and the rotation speed target signal ω ^*
And the deviation is calculated by the speed controller 35 to generate a rotor rotation driving force τ ^* . The state quantities FαL ^* , FβL ^* , FαR ^* , FβR ^* , k1, k2 obtained so far
, K3, k4, k5, k6, .tau. ^*
The two-phase currents IαL ^* , IβL ^* , IOL ^* , Iα
R ^* , IβR ^* , and IOR ^* are converted based on the above equation (8).

The two-phase currents obtained in this manner are converted into three-phase current command values IUL ^* , IVL ^* , IWL ^* , IUR ^* , IVR, IVR ^* corresponding to the actual winding currents by the two-phase / three-phase converter 36. Convert to IWR ^* .

In this embodiment, as shown by the equation (5), the sum of the current command values becomes zero, so that the rotating machine winding current amplifier 37 can use a six-phase inverter. FIG. 7 shows the configuration of the six-phase inverter and the connection between the windings. Rotating machine L, in the R, since it is IuL + IvL + IwL ≠ 0 IuR + IvR + IwR ≠ 0, the middle point C _L Y-connection winding of a rotating machine L and a midpoint C _R of the Y-connection winding of a rotating machine R in wire K Need to connect. One of the terminals of the six windings is connected to the output terminal of a six-phase inverter (power amplifier) via six current paths, and the other terminal of the six windings is commonly connected.

In the above embodiment, two rotors are connected in the axial direction, and the two are connected by a magnetic material so that a part of the magnetic flux flowing into (or out of) the working surface of the rotor can be partially cut in the vertical section of the rotating shaft. Outflow (in)
However, three or more rotors may be connected. Also, flows into (exits) the rotor working surface
As a structure for allowing a part of the generated magnetic flux to flow out (enter) in a section perpendicular to the rotation axis, various modes can be considered in addition to using a magnetic material for the rotation axis. Thus, various modifications can be made without departing from the spirit of the present invention.

[0042]

As described above, according to the present invention, the rotor of the rotor can be driven without winding an independent control winding on the drive winding of the stator or using many single-phase windings. Radial position control and control of the rotor driving force can be achieved simultaneously. Accordingly, the number of power amplifiers for controlling the stator winding current can be reduced, and the configuration can be simplified. Therefore, a portion corresponding to a control electromagnet of a magnetic bearing that supports the rotor in a non-contact manner can be largely omitted, and downsizing of the device, reduction in the number of parts, and accompanying significant cost reduction can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the operation principle of a bearingless rotating machine according to the present invention.

FIG. 2 is a diagram corresponding to FIG. 1 when two rotors are connected.

FIG. 3 is a longitudinal sectional view of the bearingless rotary machine according to one embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a stator magnetic pole in FIG. 3;

FIG. 5 is an explanatory diagram showing a coordinate system of a rotor.

FIG. 6 is a block diagram of a control system of the bearingless rotating machine.

FIG. 7 is a connection diagram of a stator winding of the bearingless rotating machine.

[Explanation of symbols]

 10, 21, 22 Stator 11, 12 Rotor 13 Rotation axis 13A Magnetic material 14, 15 Displacement sensor 20 Rotation angle detector L, R Rotating machine

Continuing from the front page (72) Inventor Satoshi Mori 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Inside Ebara Research Institute, Ltd. (72) Inventor Kazuki Sato 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture (72) Inventor Naofumi Kajima 4-1-1 Motofujisawa, Fujisawa-shi, Kanagawa

Claims (6)

[Claims] In a rotating machine having a cylindrical rotor on an inner periphery of a cylindrical stator, a magnetic flux generated by a magnetomotive force of a winding wound on a cylindrical surface inside the stator is generated by the rotor cylindrical surface. A bearingless rotating machine characterized by controlling the position of two axes orthogonal to each other in the radial direction of the rotor and controlling the rotational driving force of the rotor by passing through a cross section perpendicular to the rotation axis. 2. The two rotating machines are arranged in the direction of a rotating shaft, and the rotors of the two rotating machines are joined by a magnetic material so that the rotating shafts are the same. The magnetic flux generated by the magnetomotive force of the winding wound on the cylindrical surface passes through one of the rotor cylindrical surfaces of the rotating machine, the magnetic material, and the other rotor cylindrical surface of the rotating machine, and thereby, 2. The method according to claim 1, further comprising: controlling the position of two axes orthogonal to each other in the radial direction for each rotor, and controlling the rotational driving force of the rotor.
The bearingless rotating machine as described. 3. A distribution of a magnetomotive force generated by the winding wound around a cylindrical surface inside the stator when the rotation is rotated by half of a rotation axis of the rotor. The bearingless rotating machine according to claim 1 or 2, wherein the windings have three or more phases in which the magnetomotive force distribution when the direction of current flow is reversed is not the same. 4. The bearingless rotating machine according to claim 3, wherein when the windings are three-phase, the winding distribution of each winding has a phase difference of 120 °. 5. A six-phase power amplifier for controlling a current flowing through six windings in a bearingless rotating machine in which two rotors are joined by a magnetic material so that the rotating axes are the same. A bearing-less rotating machine characterized by using: 6. The bearingless rotating machine according to claim 5, wherein one of the terminals of the six windings and the power amplifier are connected to each other.
A bearing-less rotating machine, wherein the current terminals are connected by three current paths, and the other six of the winding terminals are all connected in common.