TW201522801A - Electric motor system and magnetic bearing system - Google Patents

Abstract

Provided are an electric motor system and a magnetic bearing system that are capable of suitable detecting the amount of eccentricity and the direction of eccentricity. An electric motor system (S) is characterized by comprising: an electric motor (1) that has a stator (2) and a rotor (6) supported by magnetic levitation and that is configured by each phase having at least two parallel coils; a circulating current detection means (21, 12) that detects the circulating current flowing in the coil for each of at least two phases among the phases; and an eccentricity estimation means (13) that estimates the amount of eccentricity and the direction of eccentricity of the rotor (6) on the basis of the circulating current detected by the circulating current detection means (21, 12).

Description

Motor system and magnetic bearing system

The invention relates to a motor system and a magnetic bearing system.

In recent years, as a bearing for supporting a high-speed rotating body such as a working machine such as a grinding spindle or a flywheel or a turbo molecular pump, the magnetic bearing is widely used. The magnetic bearing is non-contact supported by magnetic float, and can achieve high-speed rotation, no oil, no maintenance, and mechanical loss (mechanical loss) compared with conventional contact-supported bearings (for example, rolling bearings). )Wait. Further, in order to realize a maglev rotary member with a device that is lighter than a motor using a magnetic bearing in a bearing, a review of a bearingless motor having a function of a motor and a magnetic bearing is also widely conducted.

In the conventional magnetic bearing or bearingless motor, the shaft position control of the rotating member (rotor) for magnetic floating is performed, and the rotating member is detected by a non-contact type displacement sensor (for example, an eddy current type displacement sensor). The amount of eccentricity of the rotating shaft (displacement of the rotational axis position of the rotating member from the position of the central axis of the stator (stator)). For this reason, the conventional magnetic bearing or bearingless motor is compared with the bearing that performs contact support, and if the device is enlarged, there is a shaft. The length of the long-term will become longer, and the cost of the displacement sensor will become higher. Therefore, in the case of a magnetic bearing or a bearingless motor, it is desirable to have no displacement sensor.

The patent document 1 (Japanese Laid-Open Patent Publication No. Hei 11-142104) is hereby incorporated by reference. Patent Document 1 discloses a radial direction rotor position estimating device for a bearingless motor having a relationship between a displacement (eccentric amount) and a mutual inductance. In the radial direction rotor position estimating device of the bearingless motor of the patent document 1, the three-phase induced voltage is detected from the radial direction position control winding by changing the magnetomotive force distribution in the gap due to the eccentricity, and the value is estimated from the value. The position of the rotor in the radial direction (the displacement α on the α-axis and the displacement β on the β-axis, that is, the eccentric amount and the eccentric direction).

[Previous Technical Literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-142104

However, the proportional relationship between the eccentric amount and the mutual inductance as in Patent Document 1 can be applied, in the case where the stator windings of the respective phases are connected in series. On the other hand, when the stator windings of the respective phases are connected in parallel to form a parallel circuit, the circulating current is generated in the parallel circuit, so that the potential difference due to the eccentricity of the rotating shaft of the rotating member is offset, which is not applicable. The subject of the estimation method of the radial direction position (eccentric amount and eccentric direction) of the rotor disclosed in Patent Document 1 is known.

Further, in the method of estimating the radial position (eccentricity and eccentricity) of the rotor disclosed in Patent Document 1, there is a fear that it is difficult to obtain a difference in the low-speed rotation range and the error becomes large in order to detect the three-phase induced voltage. Question.

Here, as a subject, the present invention provides a motor system and a magnetic bearing system suitable for detecting an eccentric amount and an eccentric direction.

In order to solve such a problem, the motor system according to the present invention includes: a motor having a fixing member and a rotating member supported by the magnetic floating, wherein each phase is formed by connecting at least two or more coils in parallel; and the circulating current detecting means is At least two of the respective phases are detected by a circulating current flowing through the coil; and the eccentricity estimating means estimates the eccentric amount and the eccentricity of the rotating member based on the circulating current detected by the circulating current detecting means direction.

Further, the magnetic bearing system according to the present invention includes: a magnetic bearing having a fixing member and a rotating member supported by the magnetic floating, wherein each phase is constituted by at least two or more coils connected in parallel; and the circulating current detecting means is described above. At least two phases of the respective phases are detected by the circulating current flowing through the coil, and the eccentricity estimating means estimates the eccentric amount and the eccentric direction of the rotating member based on the circulating current detected by the circulating current detecting means.

According to the present invention, it is possible to provide a motor system and a magnetic bearing system suitable for detecting an eccentric amount and an eccentric direction. According to this, even if an expensive displacement sensor (for example, an eddy current type displacement sensor) is not used, it is possible to detect the eccentric amount and the eccentric direction, and realize the axis of the rotary member (rotor) at low cost. Position control.

S, SA, SB‧‧‧ motor system (magnetic bearing system)

1‧‧‧Electric motor (magnetic support device, bearingless motor, magnetic bearing)

2‧‧‧Fixed parts

3‧‧‧Fixed core

4‧‧‧ teeth

5‧‧‧Fixed parts winding

6‧‧‧Rotating parts

7‧‧‧Rotating iron core

8‧‧‧ permanent magnet

9‧‧‧ gap

10‧‧‧Neutral point

10a, 10b‧‧‧ connection points

11‧‧‧ Controller

12‧‧‧Circuit current detection unit (circulating current detection means)

13‧‧‧Eccentricity and eccentricity estimation unit (eccentricity estimation method)

14‧‧‧Axis Position Control Department

21, 21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ‧‧‧ current sensor (circulating current detection means)

22 _U , 22 _W ‧‧‧ current comparator (circulating current detection means, differential current detection means)

U‧‧‧U phase

V‧‧‧V phase

W‧‧‧W phase

U1, U2, V1, V2, W1, W2‧‧‧ coil

Fig. 1 is a block diagram showing the configuration of a motor system according to a first embodiment.

Fig. 2 is a circuit configuration diagram of a motor system according to the first embodiment.

Fig. 3A is a cross-sectional view of the motor in the axial direction.

FIG. 3B is a cross-sectional view of the motor in the axial direction when eccentric.

Fig. 4 is a view showing the relationship between the eccentricity of the rotating shaft of the rotor and the gap width.

FIG. 5 is a circuit diagram for explaining a current flowing in each coil of the motor (neutral point wiring) of the motor system according to the first embodiment.

Fig. 6 is a circuit configuration diagram of a motor system according to a second embodiment.

Fig. 7 is a circuit diagram for explaining a current flowing in each coil of a motor (neutral point unwired) of the motor system according to the second embodiment.

[Fig. 8] is a circuit configuration of a motor system according to a third embodiment Mapping.

FIG. 9 is a perspective view showing a method of mounting the current sensor according to the third embodiment.

Hereinafter, the mode for carrying out the invention (hereinafter referred to as "the embodiment") will be described in detail with reference to the appropriate drawings. In the respective drawings, the same reference numerals are given to the same parts, and the repeated description is omitted.

≪First Embodiment≫

<Motor system>

The motor system S according to the first embodiment will be described with reference to Figs. 1 to 5 . Fig. 1 is a block diagram showing the configuration of a motor system S according to the first embodiment.

As shown in FIG. 1, the motor system S includes an electric motor (magnet support device) 1, a controller 11, and a current sensor 21.

The motor (magnetic float support device) 1 is a bearingless motor that magnetically floats the rotary member 6 (see FIGS. 3A and 3B described later) to perform non-contact support.

In addition, the motor system S of the first embodiment is described as a motor that uses a bearingless motor that magnetically floats the rotary member 6 to perform non-contact support as a motor (magnet support device) 1 to perform shaft position control of the rotary member 6. System S; but the maglev support device is not limited to no shaft Magnetic bearings can also be used. That is, the magnetic bearing (magnetic floating support device) 1 for magnetically floating the rotating member for non-contact support can also be applied to the magnetic bearing system S for performing the axial position control of the rotary member 6.

The controller 11 is connected to the motor 1 for controlling the shaft position of the rotary member 6 of the motor 1, and inputs a current or a voltage from the controller 11 to the motor 1. On the other hand, the winding of the motor 1 is detected by the current sensor 21 (the current sensors 21 _U1 , 21 _U2 , 21 _W1 , 21 _{W2 of} FIG. 2 described later) (the coils U1 and U2 of FIG. 2 described later). The current flowing through the windings 5) of W1, W2, and 3A, 3B is fed back to the controller 11. Next, the controller 11 obtains a circulating current flowing in the coil (winding) from the measured current value, and simultaneously obtains the eccentric amount and the eccentric direction of the rotating member 6, and reduces the motor 1 via the input current or the voltage. The aforementioned circulating current allows the shaft position control of the rotary member 6 of the motor 1 to be performed.

Fig. 2 is a circuit configuration diagram of a motor system S according to the first embodiment. In the case where the motor (magnetic support device) 1 is a bearingless motor, the circuit for controlling the shaft position control of the rotary member 6 (see FIGS. 3A and 3B to be described later) and the rotation for rotating the rotary member 6 are provided. A circuit using a winding; however, in Fig. 2, a circuit for controlling the winding position of the shaft of the rotary member 6 is disclosed.

As shown in Fig. 2, the motor (magnetic float support device) 1 is subjected to 3-phase alternating current of U phase (symbol U in Fig. 2), V phase (symbol V in Fig. 2), and W phase (symbol W in Fig. 2). Drive, two coils in each phase (coupling U1, U2, V-phase coil V1, V2, W-phase coil) W1, W2) are connected in parallel with each other in the same phase to form a parallel circuit. Further, the six coils U1, U2, V1, V2, W1, and W2 are wired at the neutral point 10.

The current sensor 21 (see FIG. 1) has a current sensor 21 _U1 that detects the current of the coil _U1 , a current sensor 21 _U2 that detects the current of the coil _U2 , and a detection coil W1, as shown in FIG. Current sensor 21 _W1 and current sensor 21 _{W2 for} detecting current of coil _W2 . The current sensors 21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 feed back the detected current values to the controller 11 .

The controller 11 includes a circulating current detecting unit 12, an eccentric amount and eccentricity direction estimating unit 13, and an axis position control unit 14.

The circulating current detecting unit (circulating current detecting means) 12 detects (calculates) U based on the current I _U1 detected by the current sensor 21 _U1 and the current I _U2 detected by the current sensor 21 _U2 . The circulating current I _{CIR_U of the phase} . Further, the W-phase circulating current I _{CIR_W is} detected (calculated) based on the current I _W1 detected by the current sensor 21 _W1 and the current I _W2 detected by the current sensor 21 _W2 . The method of obtaining the circulating current of the circulating current detecting unit 12 will be described later.

The eccentric amount and the eccentricity direction estimating unit (eccentricity estimating means) 13 estimates (calculates) the rotary member 6 based on the U-phase circulating current I _{CIR_U} detected by the circulating current detecting unit 12 and the W-phase circulating current I _{CIR_W} ( Refer to the eccentric amount and the eccentric direction of the rotating shaft of FIGS. 3A and 3B) which will be described later. In this way, the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ), the circulating current detecting unit 12 of the controller 11 , the eccentric amount of the controller 11 , and the eccentric direction estimating unit 13 constitute the detecting rotating member 6 The eccentricity of the rotating shaft and the eccentricity detecting device of the rotating member in the eccentric direction. In addition, the method of estimating (calculating) the eccentric amount and the eccentric amount and the eccentric direction of the eccentricity direction estimating unit 13 will be described later.

The axis position control unit 14 reduces the amount of eccentricity based on the amount of eccentricity and the eccentricity estimated by the eccentric amount and the eccentricity direction estimating unit 13, and in other words, the input current or the voltage is applied to the U phase, the V phase, and the W phase. The shaft position of the rotary member 6 of the motor 1 is controlled such that the circulating current I _{CIR_U} and the circulating current I _{CIR_W are} reduced.

In addition, the motor system S of the first embodiment is described as a current for detecting the winding of the shaft position control of the rotary member 6 as the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ). But not limited to this. The winding for rotating the rotating member 6 is such that two coils of each phase are connected in parallel with each other in the same phase to form a parallel circuit, and a current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ) to detect the current of the winding for the rotation of the rotary member 6. In this manner, the eccentricity detecting device (the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ), the circulating current detecting unit 12 of the controller 11, and the eccentric amount and the eccentric direction of the controller 11 are estimated. Similarly, the eccentric amount and the eccentric direction of the rotating shaft of the rotor 6 can be detected in the same manner. In this case, the axial position control unit 14 of the controller 11 is based on the eccentric amount and the eccentric direction estimating unit 13. The estimated eccentric amount, eccentric direction, input current or voltage to the U-phase, V-phase, and W-phase of the shaft position control winding of the rotary member 6, and the axial position control of the rotary member 6 of the motor 1 is performed to make the eccentric amount Zoom out.

Further, when the motor of the motor system S is composed of a motor (not a bearingless motor) and two magnetic bearings, the winding (rotation winding) for rotating the rotating member of the motor is attached to When two coils of each phase are connected in parallel in the same phase and form a parallel circuit, a current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ) may be provided to detect the winding of the motor (for rotation) Winding) current. In this manner, the eccentricity detecting device (the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ), the circulating current detecting unit 12 of the controller 11, and the eccentric amount and the eccentric direction of the controller 11 are estimated. Similarly, the eccentric amount and the eccentric direction of the rotating shaft of the rotor 6 can be detected in the same manner. In this case, the axial position control unit 14 of the controller 11 is based on the eccentric amount and the eccentric direction estimating unit 13. The estimated eccentricity and eccentric direction control two magnetic bearings to control the shaft position of the rotating parts of the motor.

<motor>

Next, the motor (magnetic float support device, bearingless motor) 1 relating to the motor system S of the first embodiment will be further described with reference to FIG. 3A. 3A is a cross-sectional view of the motor 1 in the axial direction.

As shown in FIG. 3A, the motor 1 includes a stator core 3, a fixing member 2 having teeth 4 and a fixing member winding 5, and an inner peripheral side of the fixing member 2 and having a rotating core 7 and a permanent magnet 8. Rotating member 6. The rotating member 6 for magnetic floating is supported by the fixing member 2 in a non-contact manner via a gap 9 between the fixing member 2 and the rotating member 6.

In the fixing member 2, the teeth 4 are arranged radially at 60° in the circumferential direction, and the fastener windings 5 are wound around the teeth 4 to form coils (coils U1, U2, V1, V2, W1, W2 of Fig. 2). Further, the fixing member winding 5 and the three-phase winding are arranged in the circumferential direction in the order of the U phase, the V phase, and the W phase, and each phase has two coils, and U1, V1, W1, U2, and V2 are used. The order of W2 is arranged in the circumferential direction.

<Relationship between circulating current and eccentricity>

The rotor eccentricity detecting device (the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , 21 _W2 ) of the motor system S according to the first embodiment, the circulating current detecting unit 12 of the controller 11, and the eccentricity of the controller 11 The amount and eccentricity direction estimating unit 13) estimates the eccentric amount and the eccentric direction from the detected circulating current. The basic principle of estimating the eccentric amount and the eccentric direction from the circulating current will be described with reference to Figs. 2 to 5 . 3B is a cross-sectional view of the motor 1 in the axial direction when eccentric. 4 is a view showing a relationship between an eccentricity of a rotation axis of the rotor 6 and a gap width. Fig. 5 is a circuit diagram for explaining a current flowing in each coil of the motor 1 (neutral point wiring) of the motor system S according to the first embodiment. Further, in the following description, the difference in impedance between the coils (fixing member windings 5) is caused by the error at the time of production, but the difference in impedance is assumed to be zero. Incidentally, if the rotating member 6 is in an unbiased state, the voltage induced in the coil (the fixing member winding 5) of the same phase is equal, and no circulating current is generated.

[Detection of circulating current]

First, as shown in FIG. 5, the currents I _U , I _V , and I _{W are} input from the controller 11 (see FIG. 2 ) to the U phase, the V phase, and the W phase of the motor 1 . In the case where the impedance of each coil (fixing member winding 5) is not greatly different, these currents are roughly divided into two equal parts, and current flows in each coil (fixing member winding 5). Let the current flowing in the coil U1 be I _U1 , the current flowing in the coil U2 be I _U2 , the current flowing in the coil V1 be I _V1 , the current flowing in the coil V2 be I _V2 , and the current flowing in the coil W1 be I _{W1 .} The current flowing through the coil W2 is I _W2 . When the difference in impedance is 0, there is no eccentricity, and I _U1 = I _U2 , I _V1 = I _V2 , and I _W1 = I _W2 .

On the other hand, when eccentricity occurs, a potential difference ΔE is generated between the in-phase coils constituting the parallel circuit, and in order to offset this, a circulating current is generated in the closed circuit of the parallel circuit, and I _U1 ≠I _U2 and I _V1 ≠ The relationship between I _V2 and I _W1 ≠I _W2 . Here, the circulating current of the U-phase parallel circuit (the circuit composed of the coil U1 and the coil U2) is I _{CIR, U} , because I _U1 = I _U / 2 + I _{CIR, U} , I _U2 = I _U / 2-I _CIR, because of the relationship of the _U, the current flowing in coils U1 and _U1 can strike the I I _CIR circulating current in the U-phase coil U2 _U2 current flowing in the _{I, U.} The same applies to the V phase and the W phase. That is, the U-phase circulating current I _{CIR, the U} , V-phase circulating current I _{CIR, and the V-} phase circulating current I _{CIR, W} are as follows.

I _{CIR, U} = (I _U1 -I _U2 )/2. . . (1a)

I _{CIR, V} = (I _V1 -I _V2 )/2. . . (1b)

I _{CIR, W} = (I _W1 -I _W2 )/2. . . (1c)

In this manner, the circulating current detecting unit 12 of the controller 11 can obtain the U-phase circulating current I _{CIR, U} from the current detected by the current sensors 21 _U1 , 21 _U2 and the equation (1a). Further, the circulating current detecting portion 12 of the controller 11 can obtain the circulating current I _{CIR, W of the} W phase from the current detected by the current sensors 21 _W1 , 21 _W2 and the equation (1c).

[The relationship between eccentricity and circulating current]

Next, the potential difference ΔE of each coil at the time of occurrence of eccentricity will be described.

When the magnetic permeability of iron is ∞, and the residual magnetic flux density of the magnet is Br, the return permeability is μ _m , the thickness of the magnet is hm, and the gap width is δ, the magnetic flux density B _δ of the gap 9 is as follows. .

B _δ =Br*hm/( δ * μ _m +hm). . . (2a)

Here, when δ < hm, the constant κ can be regarded as follows.

B _δ = κ / δ . . . (2b)

In the following description, the case where δ<hm is satisfied is described. However, when δ≧hm is satisfied, the relational expression can be obtained from the formula (2a), and the same effect as in the present embodiment can be obtained. .

Here, the magnetic flux density B _δ of the gap 9 is a peak value, and the fundamental wave component of the magnetic flux density B _δ of the gap 9 is integrated in the circumferential direction by the width of the tooth 4 as the magnetic flux φ which is interlinked to the tooth 4. . Next, the time differential of the magnetic flux φ is taken as the induced electromotive force E generated in each coil. That is, it becomes as follows.

E = α B _δ = κα / δ . . . (3)

Further, the induced electromotive force E, the magnetic flux density B _δ of the gap 9 is proportional to the frequency f.

As shown in FIG. 4, the gap width of the state which is not eccentric is taken as δ, and when the eccentricity (x, y) occurs (indicated by a broken line), the gap width δ _new of the teeth 4 at a certain angle θ _t is resisted. Become as follows.

δ _new = δ -(x×cos( θ _t )+y×sin( θ _t )). . . (4)

Also, x and y are eccentric coordinates; θ _t is the mechanical angle of the center of the tooth 4. At this time, θ _t is desirably the center angle of the teeth 4, but there is a slight error.

The voltage E induced by the coil (fixing member winding 5) of the tooth 4 at the angle θ _t where the eccentricity occurs is changed in accordance with the value of the gap width δ before the eccentricity and the gap width δ _new after the eccentricity. , change in the following proportions.

δ / δ _new . . . (5)

In other words, when the δ _new >δ, the induced electromotive force E becomes smaller, and when the δ _new <δ, the induced electromotive force E becomes larger.

A coil 1 and coil 2 of the same phase form a parallel circuit (closed loop). When the mechanical angle of the coil 1 and the coil 2 is θ _t,1 , θ _{t, 2} , the potential difference ΔE when the eccentricity occurs is determined by the formula (3). ) and formula (4), become formula (6).

Further, as described above, after the eccentricity occurs, a potential difference ΔE is generated between the coil 1 and the coil 2, and in order to cancel the potential difference, a circulating current I _cir is generated in the parallel circuit (closed circuit), so that the closed circuit is closed. When the impedance is Z _{1_2} , it becomes as follows.

△E=I _cir Z _{1_2} . . . (7)

From the equations (6) and (7), the relationship between the eccentricity (x, y) and the circulating current I _cir becomes the formula (8).

Next, the case where the rotator 6 shown in FIG. 3B is eccentric in the direction of the coil U1 (the positive X-axis direction) and eccentricity is taken as an example, the relationship between the eccentricity and the circulating current is further explained. In Fig. 3B, it is eccentric (δe, 0) under the X-Y coordinate system.

When the rotating member 6 is eccentric in the direction of the coil U1, the gap in the direction of the coils U1, V1, and W2 is narrower than before the eccentricity (refer to FIG. 3A); the gap in the direction of the coils U2, V2, and W1 is wider than before the eccentricity (refer to FIG. 3A). . Specifically, the teeth 4 are determined such that the mechanical angle θ _{t is} arranged at intervals of 60° in the circumferential direction, and the gap width δ _{new in} a state in which eccentricity (δe, 0) occurs can be obtained by the formula (4).

Gap width in the direction of coil U1 ( θ _t =0°): ( δ - δ e)

Gap width in the direction of coil U2 ( θ _t =180°): ( δ + δ e)

Gap width in the direction of coil V1 ( θ _t = 60°): ( δ - δ e/2)

Gap width in the direction of coil V2 ( θ _t = 240°): ( δ + δ e/2)

Gap width in the direction of coil W1 ( θ _t =120°): ( δ + δ e/2)

Gap width in the direction of coil W2 ( θ _t =300°): ( δ - δ e/2)

The potential difference △ E _V between the coils U1, the potential difference △ E _U between the coils U2, the coils V1, the coil V2, and the coil W1, the potential difference △ E _W between the coils W2, lines may be obtaining by equation (5).

△E _U =E _U1 -E _U2 = ακ (1/( δ - δ e)-1/( δ + δ e))

△E _V =E _V1 -E _V2 = ακ (1/( δ - δ e/2)-1/( δ + δ e/2))

△E _W =E _W1 -E _W2 = ακ (1/( δ + δ e/2)-1/( δ - δ e/2))

Here, when the coils of the same phase constitute a parallel circuit, the circulating currents I _{CIR, U} , I _{CIR, V} , I _{CIR are} generated in such a manner as to cancel the potential differences ΔE _U , ΔE _V , and ΔE _{W . W.} Let the fundamental wave angle frequency be ω, the impedance of the 1 coil be R, and the inductance of the 1 coil be L. According to Ohm's law, the circulating current I _CIR is expressed by the formula (9).

When reflecting the phase of each actual coil, the circulating current becomes as follows: I _{CIR, U} ×cos( ω t)=ΔE _U /(2R+2j ω L)

I _{CIR, V} ×cos( ω t-3/2× π )=ΔE _V /(2R+2j ω L)

I _{CIR, W} × cos( ω t - 4 / 2 × π ) = ΔE _W / (2R + 2j ω L) ; cos (ωt), that is, a function of the position of the circumferential direction of the rotor 6 and the potential difference. Next, when the potential differences ΔE _U , ΔE _V , and ΔE _W are substituted, the following formulas (10a) to (10c) are obtained.

Here, as shown in the formulas (1a) to (1c), the circulating currents I _{CIR, U} , I _{CIR, V} , I _{CIR, W} are obtained from the current values detected by the current sensor. The value is a known value. Further, when the motor 1 is a bearingless motor or the like, the circumferential position of the rotary member 6, that is, the electrical angle of the motor 1 is a known value. Further, the gap width δ, the impedance R, and the inductance L of the state that has not been eccentric are also known values. Thus, the unknown of the formula (10a) to the formula (10c) is the eccentric amount δe, that is, only the eccentricity (δe, 0).

Therefore, the eccentricity (x, y), that is, the eccentric amount and the eccentric direction can be obtained by detecting at least two circulating currents. Further, when cos(ωt) is unknown, the eccentric amount and the eccentric direction can be obtained by detecting the circulating current at three places.

Moreover, the impedance is roughly proportional to the frequency, and the voltage sensed by each coil is also proportional to the frequency. For this reason, it can also be understood from the formula (8) that the circulating current can be said to have almost no frequency dependence. Therefore, the eccentric amount and the eccentric direction can be estimated with high accuracy even in the low-speed rotation range.

In this way, the eccentricity amount and the eccentricity direction estimating unit 13 of the controller 11 are the circulating current I _CIR of the U phase _{, the U} , and the circulating current I _{CIR, W of the} W phase, and the formula (determined by the circulating current detecting unit 12). 8) The relationship can be obtained by eccentricity (x, y), that is, eccentricity and eccentricity. Then, the shaft position control unit 14 of the controller 11 controls the shaft position of the rotor 6 of the motor 1 based on the eccentric amount and the eccentricity direction obtained by the eccentric amount and the eccentric direction estimating unit 13, even at a low speed. The rotation range also enables axis position control with high precision.

As described above, in the motor system (magnetic bearing system) S of the first embodiment, the current sensor can be used to obtain the eccentric amount and the eccentric direction, and the shaft position can be controlled. Compared with a displacement sensor (for example, an eddy current displacement sensor), the current sensor is inexpensive, and the space for mounting the sensor is also small, and the conventional displacement sensing is used. Compared with the motor system (magnetic bearing system) for controlling the position of the shaft, it can be used as a low-cost, space-saving motor system (magnetic bearing system) S. In addition, compared with the conventional radial direction rotor position estimating device (Patent Document 1), the motor system (magnetic bearing system) S according to the first embodiment can accurately obtain the eccentricity and the amount even in the low-speed rotation range. In the eccentric direction, the axis position control is performed.

≪Second embodiment≫

Next, the motor system (magnetic bearing system) SA according to the second embodiment will be described with reference to FIGS. 6 and 7 . Fig. 6 is a circuit configuration diagram of a motor system SA according to a second embodiment. Fig. 7 is a circuit diagram for explaining a current flowing in each coil of the motor 1A (neutral point unwired) of the motor system SA according to the second embodiment.

The electric motor 1 of the motor system S of the first embodiment is a motor 1 that is connected to the neutral point 10 as shown in FIGS. 2 and 5, whereas the motor system SA of the second embodiment is related to the motor system SA of the second embodiment. The motor 1A is different as shown in Figs. 6 and 7 in that the motor is not wired at the neutral point. In other words, in the motor 1 of the motor system S according to the first embodiment, six coils U1, U2, V1, V2, W1, and W2 are connected at the neutral point 10, whereas the motor system according to the second embodiment is related to the second embodiment. The motor 1A of S is different in that the coils U1, V1, and W1 are connected at the connection point 10a, and the coils U2, V2, and W2 are connected at the connection point 10b. The other configurations are the same, and the description thereof is omitted.

In the case of such a motor 1A that is not wired at the neutral point, as shown in Fig. 7, the circulating current is generated across the other phases. That is, a circulating current I _CIR across the U phase and the V phase _{, UV} , a circulating current I _CIR across the V phase and the W phase _{, VW} , and a circulating current I _CIR across the W phase and the U phase _{, WU} .

Thus, the path of the circulating current becomes complicated, and the circulating current I _{cir, U1} generated in the coil U1 and the circulating current I _cir generated in the coil U2 _{, U2} become I _{cir, U1} = I _{CIR, UV -} I _{CIR, WU} = - I _{cir, U2} . Similarly, the circulating current I _{cir, V1} generated in the coil _V1 , and the circulating current I _{cir, V2} generated in the coil V2 become I _{cir, V1} = -I _{cir, V2} , and the circulating current I _{cir, W1} generated in the coil _W1 , And the circulating current I _cir generated in the coil W2 _{, W2} becomes I _{cir, W1} = -I _{cir, W2} .

Therefore, similarly to the current sensor 21 of the motor system S according to the first embodiment, the current sensors 21 _U1 and 21 _{U2 are} provided in the coils U1 and _U2 , and the circulating current detecting unit 12 can be used to obtain the circulating current I _{cir. , U1} = (I _{U1 -} I _U2 )/2. Further, the coils W1, W2 has a current sensor 21 _W1, 21 _W2, may be circulating current detecting section obtains the circulating current _{I cir, W1 = (I W1} -I W2) 12/2. Next, the eccentric amount of the controller 11 and the eccentric direction estimating unit 13 can obtain the eccentric amount and the eccentric direction from the circulating currents I _{cir, U1} and I _{cir, W1} by the same principle as in the first embodiment.

≪The third embodiment≫

Next, the motor system (magnetic bearing system) SB according to the third embodiment will be described with reference to FIGS. 8 and 9. Fig. 8 is a circuit configuration diagram of a motor system SB according to a third embodiment. Fig. 9 is a perspective view showing a method of mounting the current sensor 22 _U according to the third embodiment.

As shown in FIG. 8, the motor system SB according to the third embodiment is provided instead of the current sensor 21 (21 _U1 , 21 _U2 , 21 _W1 , and 21 _W2 ) of the motor system S according to the first embodiment. The current transformers 22 _U and 22 _W are different. The other configurations are the same, and the description thereof is omitted.

As shown in Fig. 9, the winding 5a of the coil U1 and the winding 5b of the coil U2 are inserted into the measuring portion of the current transformer 22 _U so that the current directions are opposite to each other. Thereby, the current transformer 22 _U detects the differential current (I _{U1 -} I _U2 ) of the current I _{U1 of the} coil U1 and the current I _U2 of the coil U2. Next, the circulating current detecting unit 12 obtains the U-phase circulating current I _{CIR, U} from the equation (1a). The same is true about the W phase.

As described above, according to the motor system (magnetic bearing system) SB according to the third embodiment, the number of sensors can be reduced from four to two. Further, in the case of the motor system S according to the first embodiment, when the weight of the rotor 6 increases, the current value flowing through the coil also increases, and the measurement range of the current sensor 21 also increases, and it is necessary to use high. Price, large current sensor. On the other hand, in the case of the motor system SB according to the third embodiment, since the differential current (I _{U1 -} I _U2 ) is detected, the measurement ranges of the current transformers 22 _U and 22 _W are also small, and it is possible to use inexpensive, Small product. In the case of the current transformers 22 _U and 22 _W using the current transformer method, the current sensor is obtained by calculating the magnetic field strength from the current in the insertion hole of the current sensor. Other methods of current sensors can also be used.

≪ ≫ ≫

In addition, the motor systems (magnetic bearing systems) S, SA, and SB according to the present embodiment are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

The motor system (magnetic bearing system) S, SA, and SB of the present embodiment has been described as a motor system (magnetic bearing system) without a displacement sensor, but is not limited thereto. A rotating member eccentricity detecting device provided in the motor system (magnetic bearing system) S, SA, and SB according to the present embodiment, and a measuring method using a conventional displacement sensor or a probe coil may be used in combination. Through this, you can do more accurate measurement. Moreover, the use of different methods to measure the amount of eccentricity also enhances safety.

As shown in FIG. 2 and the like, the coils of the respective phases of the motor 1 are arranged in parallel for two coils, but the present invention is not limited thereto, and three may be used. The coils on the top are arranged in parallel. Also in this case, the eccentric amount and the eccentric direction can be estimated from the circulating current so as to obtain the relationship of the formula (7) in each closed circuit. Further, although the three-phase electric motor 1 has been described, the present invention is not limited thereto, and the two phases are preferably six phases, and may be other phases.

In FIG. 3A, the motor 1 as the rotor 6 having the internal transformation is described. However, the present invention is not limited thereto, and an electric motor including a rotor having the same configuration and other transformations may be applied. Further, although the number of poles of the rotor 6 is shown as a four-pole, it is not limited thereto, and may be two poles or six poles or more. Further, although the motor 1 has been described as a radial air gap in which the gap magnetic flux transmits in the radial direction, the present invention is not limited thereto, and the gap magnetic flux may be applied to the axial flow gap type in the axial direction. Further, the electric motor 1 is used as a permanent magnet synchronous machine. However, if the wiring of the fixing member winding 5 on the side of the fixing member 2 is made in parallel or in parallel to generate a circulating current, an induction motor, a winding synchronous machine, and an SR can be applied. Motor, etc. Further, the fixing member 2 is a concentrated winding shape of 2:3, but is not limited thereto, and a distributed winding or a concentrated winding other than 2:3 may be applied. Further, the stator core 3 and the rotor core 7 are preferably laminated on the laminated steel sheet in the axial direction, and may be formed of a powder magnetic core or the like, or may be formed of an amorphous metal or the like.

Further, the relationship between the eccentricity (x, y) and ΔE is described as the formula (6), but when the eccentric amount is small, the eccentric amount and ΔE may be proportional.

S‧‧‧Motor system (magnetic bearing system)

1‧‧‧Electric motor (magnetic support device, bearingless motor, magnetic bearing)

11‧‧‧ Controller

21‧‧‧ Current sensor (circulating current detection means)

Claims (13)

A motor system comprising: a motor having a fixing member and a rotating member supported by the magnetic floating, wherein each phase is formed by paralleling at least two or more coils; and the circulating current detecting means is at least two phases of the respective phases. And detecting the circulating current flowing through the coil; and the eccentricity estimating means estimating the eccentric amount and the eccentric direction of the rotating member based on the circulating current detected by the circulating current detecting means. The motor system according to claim 1, wherein the eccentricity estimating means is based on the gap between the rotating member before the eccentricity and the fixing member, and the gap between the rotating member and the fixing member after the eccentricity. The value of the eccentricity and the eccentric direction are estimated. The motor system according to claim 2, wherein the eccentricity estimating means estimates the eccentric amount and the eccentric direction based on a product of a circulating current value detected by the circulating current detecting means and an impedance of the motor. The motor system according to claim 3, wherein the coil includes a first coil and a second coil; and the first coil and the second coil form a closed loop; and the impedance of the closed loop is Z _{1_2} , and the closed The circulating current of the circuit is I _cir , and the mechanical angle of the first coil is θ _t,1 , so that the mechanical angle of the second coil is θ _t,2 , and the gap width of the state that has not been eccentric is δ, The coefficient ακ is located at an eccentricity (x, y) of the XY plane in which the rotation axis direction of the rotating member is a normal line, and the eccentricity estimating means is based on the following mathematical expression. The eccentricity and the eccentricity (x, y) of the eccentric direction are estimated by the circulating current I _cir . The motor system according to claim 1, wherein the coil includes: a first coil; and a second coil disposed in parallel with the first coil; and the circulating current detecting means includes a differential current detecting means, and the pair is A differential current between a current flowing through the first coil and a current flowing in the second coil is detected, and the circulating current is detected based on the differential current. The motor system of claim 1, further comprising: an additional sensor for detecting the eccentric amount of the rotating member and the eccentric direction. The motor system of claim 1, wherein The aforementioned motor is a bearingless motor. A magnetic bearing system comprising: a magnetic bearing having a fixing member and a rotating member supported by the magnetic floating, wherein each phase is formed by paralleling at least two or more coils; and the circulating current detecting means is at least 2 of the foregoing phases. The phase is detected by the circulating current flowing through the coil; and the eccentricity estimating means estimates the eccentric amount and the eccentric direction of the rotating member based on the circulating current detected by the circulating current detecting means. The magnetic bearing system of claim 8, wherein the eccentricity estimating means is based on the gap between the rotating member before the eccentricity and the fixing member, and the gap between the rotating member and the fixing member after the eccentricity The eccentric amount and the eccentric direction are estimated by the corresponding values. The magnetic bearing system according to claim 9, wherein the eccentricity estimating means estimates the eccentric amount and the eccentric direction based on a product of a circulating current value detected by the circulating current detecting means and an impedance of the motor. The magnetic bearing system according to claim 10, wherein the coil includes a first coil and a second coil; and the first coil and the second coil form a closed circuit; and the impedance of the closed circuit is Z _{1_2} The circulating current of the closed circuit is I _cir , and the mechanical angle of the first coil is θ _t,1 , and the mechanical angle of the second coil is θ _t,2 , and the gap width of the state that has not been eccentric is δ. When the coefficient ακ is set to the eccentricity (x, y) of the XY plane in which the rotation axis direction of the rotating member is the normal line, the eccentricity estimating means is based on the following mathematical expression. The eccentricity and the eccentricity (x, y) of the eccentric direction are estimated by the circulating current I _cir . The motor system according to claim 8, wherein the coil includes: a first coil and a second coil arranged in parallel with the first coil; and the circulating current detecting means includes a differential current detecting means, wherein the pair is A differential current between a current flowing through the first coil and a current flowing in the second coil is detected, and the circulating current is detected based on the differential current. The magnetic bearing system of claim 8, further comprising: an additional sensor for detecting the eccentric amount of the rotating member and the eccentric direction.