JP2017147783A - Method of activating rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for activating a rotary machine having a magnetic bearing, which reduces a current capacity of an electric power supply for supplying an electric power to the magnetic bearing.SOLUTION: A method is for activating a rotary machine which includes: a rotation shaft 6; a dynamo-electric motor which has a rotor having a permanent magnet, and a stator; a magnetic bearing 11 that has a plurality of coils 28 arranged in circumferential direction at intervals, and supports the rotation shaft 6 in a non-contact state by being conducted to each coil 28; and an emergency bearing 13. The method for the rotary machine includes: a conductive step of flowing the largest current to one coil 28a of coils 28, which is arranged on the lower side; a coil changing step of changing the coil to which the largest current flows to the second coil 28b that is adjacent to the first coil, and is arranged on the side upper than the first coil; and a continuous changing step of repeatedly changing the coil to which the largest current flows up to a position where the rotation shaft 6 contacts an inner peripheral surface of the emergency bearing 13 and the rotation shaft 6 reaches the highest position.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for starting a rotary machine including a magnetic bearing.

  For example, in a rotating machine such as a turbo compressor applied to a turbo refrigerator, a structure in which a rotating shaft to which a rotor of an electric motor is fixed is supported by a magnetic bearing is known (see, for example, Patent Document 1). The magnetic bearing includes a plurality of electromagnet coils, and supports the rotating shaft by the attractive force of the electromagnet coils. A rotating machine having a magnetic bearing is generally provided with an emergency bearing (auxiliary bearing, touch-down bearing) that supports the rotating shaft when the magnetic bearing is stopped or abnormal.

  In such a rotating machine, when the magnetic bearing is stopped, the rotating shaft comes into contact with the emergency bearing due to its own weight. At the time of start-up, the rotating shaft is attracted and floated by flowing a large current through the electromagnetic coil on the upper side in the vertical direction among the plurality of electromagnetic coils constituting the magnetic bearing.

JP 2014-231826 A

By the way, in the case of a rotating machine having a built-in type permanent magnet motor, when the magnetic bearing is stopped, an attractive force by the permanent magnet acts on the rotating shaft in addition to its own weight. In the case of a horizontal rotating shaft, the weight of the rotating shaft and the attractive force by the permanent magnet both work downward in the vertical direction.
At the time of start-up, in order to generate an attractive force that overcomes the weight of the rotating shaft and the attractive force by the permanent magnet, it is necessary to pass a larger current to the upper electromagnetic coil of the plurality of electromagnetic coils. As a result, it is necessary to increase the current capacity of the power source that supplies power to the magnetic bearing.

  An object of this invention is to provide the starting method of the rotary machine which can reduce the current capacity | capacitance of the power supply device which supplies electric power to a magnetic bearing.

  According to the first aspect of the present invention, a method for starting a rotary machine includes a rotating shaft, a rotor that includes a permanent magnet and is fixed to an outer peripheral surface of the rotating shaft, and a stator that is disposed to face the rotor. A magnetic bearing having a plurality of coils arranged at intervals in the circumferential direction, and supporting the rotating shaft in a non-contact state by energizing the coils, and non-operation of the magnetic bearing An emergency bearing that sometimes supports the rotating shaft, and a method of starting a rotating machine, wherein among the plurality of coils, an energizing step of flowing a maximum current to one coil arranged below, and a maximum A coil changing step of changing a coil through which current flows to two coils arranged adjacent to and above the one coil, and the rotating shaft on the inner peripheral surface of the emergency bearing; Contact and said To a position where the rotation axis is highest, and a step sequential changes repeated changes of the coil to flow a largest current, the.

According to such a configuration, when the rotating shaft is levitated, the rotating shaft disposed below is lifted up to the top in the vertical direction along the emergency bearing.
Thereby, compared with the case where a rotating shaft is directly lifted to the normal levitation | floating position from the perpendicular direction lowermost part, a rotating shaft can be levitated with a smaller electric current.
That is, when the rotating shaft is lifted directly from the bottom in the vertical direction to the normal floating position, the upper coil generates an attractive force that overcomes the attractive force of the rotating shaft and the rotor's own weight and the permanent magnet of the rotor. There is a need.
On the other hand, according to the starting method of the present invention, the rotating shaft is lifted up to the uppermost part in the vertical direction along the emergency bearing. Thereby, a rotating shaft can be moved without flowing a big electric current through a coil, and the current capacity of the power supply device which supplies electric power to a radial magnetic bearing can be reduced.

  In the starting method of the rotating machine, after the continuous changing step, the current flowing through the plurality of coils disposed below among the plurality of coils is gradually increased, and the plurality of coils disposed above are A center moving step may be included in which the current to be applied is gradually reduced to move the rotating shaft to the center of rotation.

  According to such a configuration, when the rotating shaft is moved to the normal levitation position, a large current flows through the coil because the attracting force by the permanent magnet and the rotating shaft and the weight of the rotor cancel each other. Without rotating the rotation axis.

  According to the present invention, the rotary shaft is lifted up to the uppermost part in the vertical direction along the emergency bearing. Thereby, a rotating shaft can be moved without flowing a big electric current through a coil, and the current capacity of the power supply device which supplies electric power to a radial magnetic bearing can be reduced.

1 is an overall configuration diagram of a turbo compressor according to an embodiment of the present invention. It is a schematic block diagram of the radial magnetic bearing of the turbo compressor of embodiment of this invention. It is a flowchart explaining the starting method of the turbo compressor of embodiment of this invention. It is the schematic explaining the starting method of the turbo compressor of embodiment of this invention.

Hereinafter, a turbo compressor which is a rotating machine according to an embodiment of the present invention will be described in detail with reference to the drawings.
The turbo compressor is applied to a turbo chiller, a turbo heat pump, and the like (hereinafter collectively referred to as a turbo chiller), and constitutes a known refrigeration cycle together with a condenser, a throttle device, and an evaporator. The refrigerant gas is compressed into a high-pressure refrigerant gas so as to circulate in the refrigeration cycle.

As shown in FIG. 1, a turbo compressor 1 includes a casing 2 having an internal space, a permanent magnet synchronous motor 5 (hereinafter referred to as an electric motor), a rotating shaft 6 that is rotated by a driving force of the electric motor 5, and a rotation. A bearing device 10 that rotatably supports the shaft 6, a single-stage impeller 8 and a two-stage impeller 9 (hereinafter also referred to as an impeller) fixed to the rotary shaft 6, and the bearing device 10 are controlled. And a control device 7.
In the following description, the direction in which the axis A of the rotating shaft 6 extends is defined as the axial direction D. The direction orthogonal to the axis A is the radial direction. In the axial direction D, the impeller side with respect to the electric motor 5 is referred to as an axial front side D1, and the side opposite to the impellers 8 and 9 with respect to the electric motor 5 is referred to as an axial rear side D2.

  The electric motor 5, the rotating shaft 6, the bearing device 10, the first stage impeller 8, and the second stage impeller 9 are arranged in the internal space of the casing 2. The bearing device 10 includes a first radial magnetic bearing 11a and a second radial magnetic bearing 11b (hereinafter sometimes referred to as a radial magnetic bearing 11), a first thrust magnetic bearing 12a and a second thrust magnetic bearing 12b (hereinafter referred to as a radial magnetic bearing 11b). And the first critical bearing 13a and the second critical bearing 13b (hereinafter sometimes referred to as the critical bearing 13).

The electric motor 5 includes a rotor 14 fixed to the outer peripheral surface of the rotating shaft 6 and a stator 16 disposed to face the rotor 14. The electric motor 5 is fixedly installed at the central portion of the electric motor chamber 3 of the casing 2. A permanent magnet 15 is embedded in the rotor 14. The permanent magnet 15 is not limited to the embedding method, and may be a method of sticking to the surface of the rotor 14.
The stator 16 is fixed to the casing 2. A coil (not shown) is wound around the stator 16, and a magnetic flux is generated by energizing the coil.

  The rotating shaft 6 is installed horizontally in the internal space of the casing 2. A thrust disk 17 is fixed to the end of the axial direction rear side D2 of the rotary shaft 6. The first thrust magnetic bearing 12a and the second thrust magnetic bearing 12b are arranged to face each other with a predetermined gap across the thrust disk 17. The thrust magnetic bearing 12 generates a magnetic attractive force by the current supplied to the coil 28. The thrust magnetic bearing 12 supports a thrust load applied to the rotary shaft 6 by positioning a thrust disk 17 between the pair of thrust magnetic bearings 12.

The first radial magnetic bearing 11 a and the second radial magnetic bearing 11 b support the rotary shaft 6 so as to be rotatable in a non-contact state inside the electric motor chamber 3. The first radial magnetic bearing 11 a is disposed on the axial front side D <b> 1 of the rotor 14 of the electric motor 5. The second radial magnetic bearing 11 b is disposed on the axial rear side D <b> 2 of the rotor 14 of the electric motor 5.
The first critical bearing 13a is disposed on the axially front side D1 of the first radial magnetic bearing 11a. The second critical bearing 13b is disposed on the axial rear side D2 of the second radial magnetic bearing 11b. The critical bearing 13 is an auxiliary bearing (radial bearing) that supports the rotary shaft 6 when the radial magnetic bearing 11 fails or is not in operation. The inner diameter of the critical bearing 13 is smaller than the inner diameter of the radial magnetic bearing 11.

The compression chamber 4 of the casing 2 incorporates a two-stage compression mechanism including a low-stage compression section 18 in which a single-stage impeller 8 is disposed and a high-stage compression section 19 in which a two-stage impeller 9 is disposed. ing. The two-stage compression mechanism compresses the low-pressure refrigerant gas sucked from the suction port via the inlet vane 21 by the low-stage side compression unit 18, sucks the discharge gas by the high-stage side compression unit 19, and forms the two-stage refrigerant into the high-pressure refrigerant gas. Compress. Each impeller 8, 9 is directly connected to the axial front side D <b> 1 of the rotary shaft 6 and is driven to rotate by the electric motor 5.
The first stage impeller 8 and the second stage impeller 9 are so-called open type impellers in which the shrouds 23 and 24 are separated from the respective impellers and provided on the casing 2 side.

  As shown in FIG. 2, the radial magnetic bearing 11 includes a cylindrical portion 26 that is formed concentrically with the rotating shaft 6, a plurality of projections 27 that protrude radially inward of the cylindrical portion 26, and each projection 27. And a coil 28 (electromagnetic coil) that is wound. The plurality of coils 28 (projections 27) are provided at equal intervals in the circumferential direction of the rotating shaft 6. The plurality of coils 28 are connected to the power supply device 22 (driver, see FIG. 1). The power supply device 22 and the control device 7 are electrically connected.

The radial magnetic bearing 11 has a displacement sensor (not shown) that detects the distance between the outer peripheral surface of the rotating shaft 6 and the coil 28.
The radial magnetic bearing 11 levitates and supports the rotating shaft 6 by energizing the plurality of coils 28 to cause the rotating shaft 6 to act on the rotating shaft 6 as a magnetic force in a direction that balances the coils 28.

The radial magnetic bearing 11 of the present embodiment includes four coils 28 of a first coil 28a, a second coil 28b, a third coil 28c, and a fourth coil 28d that are arranged at equal intervals (90 °) in the circumferential direction. ing. The four coils 28 are arranged in the order of the first coil 28a, the second coil 28b, the third coil 28c, and the fourth coil 28d in the circumferential direction. Of the four coils 28, the first coil 28 a and the fourth coil 28 d are disposed below the rotating shaft 6. The first coil 28a and the fourth coil 28d are disposed at a position shifted by 45 ° in the circumferential direction from the lowermost part P1 of the cylindrical portion 26.
Of the four coils 28, the second coil 28 b and the third coil 28 c are disposed above the rotating shaft 6. The second coil 28b and the third coil 28c are disposed at a position shifted by 45 ° in the circumferential direction from the uppermost portion P2 of the cylindrical portion 26.
The number of the coils 28 is not limited to four, and can be appropriately changed according to the weight of the rotating shaft 6 and the rotor 14.

  Next, a startup method of the turbo compressor 1 of the present embodiment will be described. The starting method of the turbo compressor 1 of the present embodiment is mainly a control method of the radial magnetic bearing 11. The control device 7 stores a control method based on the number and position of the coils 28, the weight of the rotary shaft 6 and the rotor 14, and the like. Moreover, in the control method demonstrated below, the control apparatus 7 controls the 1st radial magnetic bearing 11a and the 2nd radial magnetic bearing 11b simultaneously similarly.

As shown in FIG. 3, the start-up method of the turbo compressor 1 according to the present embodiment includes an energization step S <b> 1 for passing a current through a first coil 28 a that is one coil disposed below among the plurality of coils 28. The coil changing step S2 for changing the coil through which the current flows to the second coil 28b, which is the second coil disposed adjacent to the first coil 28a and above the first coil 28a, and the rotating shaft 6 The continuous change step S3 that repeats the change of the coil 28 through which the current flows to the position where it comes into contact with the inner peripheral surface of the critical bearing 13 and reaches the highest position, and the rotary shaft 6 floats at the normal floating position (rotation center). And a position movement process S4 to be controlled.
The normal flying position of the rotating shaft 6 is a position where the gap between the outer peripheral surface of the rotating shaft 6 and the critical bearing 13 (radial magnetic bearing 11) is constant in the circumferential direction.

  As shown in FIG. 4A, when the radial magnetic bearing 11 is stopped, the rotating shaft 6 is in contact with the inner peripheral surface of the emergency bearing 13 by gravity and is positioned at a position where the rotating shaft 6 is lowest. . Both the own weight G of the rotor 14 and the attractive force M due to the magnetic force acting between the rotor 14 (permanent magnet 15) and the stator 16 act on the rotating shaft 6.

In the energization step S1, the control device 7 controls the power supply device 22 so that a current flows only through the first coil 28a (set to the ON state). Thereby, as shown in FIG.4 (b), attraction force EM by the magnetic force of the 1st coil 28a (electromagnet coil) acts on the rotating shaft 6. FIG. The rotating shaft 6 contacts the inner peripheral surface of the emergency bearing 13 and moves to a position closest to the first coil 28a. The rotating shaft 6 moves along the inner peripheral surface of the emergency bearing 13.
Here, although the control apparatus 7 sent the electric current only to the first coil 28a, it is not limited to this. For example, the second coil 28b and the fourth coil 28d may be energized as long as the largest current flows through the first coil 28a relative to the other coils 28.

In the coil changing step S2, the control device 7 causes the power supply device 22 to pass a current only to the second coil 28b, which is a coil that is adjacent to the first coil 28a and above the first coil 28a. To control. That is, the coil through which the current flows is changed to an upper coil. Thereby, as shown in FIG.4 (c), the rotating shaft 6 contacts the internal peripheral surface of the critical bearing 13, and moves to the position nearest to the 2nd coil 28b. The rotating shaft 6 moves along the inner peripheral surface of the emergency bearing 13.
Here, the control apparatus 7 does not need to change the coil which sends an electric current instantaneously. For example, the current flowing through the first coil 28a may be gradually reduced and the current flowing through the second coil 28b may be gradually increased.
Similarly to the energization step S1, the control device 7 may energize the other coils 28 as long as the largest current flows through the second coil 28b as compared with the other coils.

  In the continuous change step S3, the control device 7 performs control to repeatedly change the coil through which current flows until the rotary shaft 6 comes into contact with the inner peripheral surface of the critical bearing 13 and the rotary shaft 6 becomes the highest. Since the radial magnetic bearing 11 of the present embodiment includes the four coils 28, the current is passed through the second coil 28b and then the current is passed through both the second coil 28b and the third coil 28c. As shown in FIG. 4 (d), the rotating shaft 6 is located at the highest position.

In the position moving step S4, the control device 7 gradually decreases the current flowing through the upper second coil 28b and the third coil 28c, and gradually increases the current flowing through the lower first coil 28a and the fourth coil 28d. By doing so, the position of the rotating shaft 6 is moved to the normal floating position. As shown in FIG. 4 (e), the control device 7 takes into consideration the weight G of the rotor 14, and the suction forces EMb and EMc acting by the upper second coil 28b and the third coil 28c are lower than the first weight. The current is controlled to be slightly larger than the attractive forces EMa and EMd acting by the coil 28a and the fourth coil 28d.
Thereby, the rotating shaft 6 moves downward from the state in contact with the inner peripheral surface of the emergency bearing 13 so as to have a constant interval in the circumferential direction between the rotary shaft 6 and the emergency bearing 13.

According to the above-described embodiment, when the rotary shaft 6 is levitated, the rotary shaft 6 disposed below is lifted up to the vertical uppermost part P2 along the emergency bearing 13 and then moved to the normal ascent position. The configuration.
Thereby, compared with the case where the rotating shaft 6 is directly lifted from the vertical direction lowermost part P1 to the normal levitation | floating position, the rotating shaft 6 can be levitated with a smaller electric current.

That is, when the rotary shaft 6 is lifted directly from the lowest vertical direction P1 to the normal levitation position, the upper coil 28 (second coil 28b and third coil 28c) is connected to the rotary shaft 6 and the rotor 14. It is necessary to generate an attractive force that overcomes the own weight G and the attractive force M by the permanent magnet 15 of the rotor 14.
On the other hand, according to the starting method of the present embodiment, the rotary shaft 6 is lifted up to the uppermost part P2 in the vertical direction along the emergency bearing 13. Thereby, the rotating shaft 6 can be moved without flowing a large current through the coil 28, and the current capacity of the power supply device 22 that supplies power to the radial magnetic bearing 11 can be reduced.
Further, when the rotating shaft 6 is moved to the normal floating position, as shown in FIG. 4E, the attractive force M by the permanent magnet 15 and the rotating shaft 6 and the own weight G of the rotor 14 cancel each other. Therefore, the rotary shaft 6 can be moved without flowing a large current through the coil 28.

  When the radial magnetic bearing 11 is not energized, the rotating shaft 6 is supported by the emergency bearing 13. Thereby, it is possible to prevent the rotary shaft 6 from coming into contact with the radial magnetic bearing 11 when the radial magnetic bearing 11 is not operated.

The embodiment of the present invention has been described in detail above, but various modifications can be made without departing from the technical idea of the present invention.
For example, the above embodiment is a method for starting a turbo compressor. However, if the rotating machine has a motor having a rotor with a permanent magnet and a magnetic bearing, the above starting method can be adopted.
Further, the number of coils constituting the magnetic bearing, the presence or absence of the thrust magnetic bearing, and the like can be appropriately changed according to the use of the rotating machine.

1 Turbo compressor (rotary machine)
DESCRIPTION OF SYMBOLS 2 Casing 3 Electric motor chamber 4 Compression chamber 5 Electric motor 6 Rotating shaft 7 Control apparatus 8 First stage impeller 9 Two stage impeller 10 Bearing apparatus 11 Radial magnetic bearing (magnetic bearing)
11a First radial magnetic bearing 11b Second radial magnetic bearing 12 Thrust magnetic bearing 12a First thrust magnetic bearing 12b Second thrust magnetic bearing 13 Critical bearing 14 Rotor 15 Permanent magnet 16 Stator 18 Low stage compression section 19 High stage compression section 22 Power supply device 28 Coil 28a First coil 28b Second coil 28c Third coil 28d Fourth coil S1 Energizing process S2 Coil changing process S3 Continuous changing process S4 Position moving process

Claims (2)

A rotation axis;
An electric motor having a rotor provided with a permanent magnet and fixed to the outer peripheral surface of the rotating shaft; and a stator disposed to face the rotor;
A magnetic bearing having a plurality of coils arranged at intervals in the circumferential direction, and supporting the rotating shaft in a non-contact state by energizing the coils;
An emergency bearing for supporting the rotating shaft when the magnetic bearing is not operated, and a starting method for a rotating machine,
An energization step of flowing the largest current through one coil arranged below among the plurality of coils,
A coil changing step of changing the coil through which the largest current flows into two coils disposed adjacent to and above the one coil; and
And a continuous change step of repeating a change of the coil through which the largest current flows until the rotary shaft is in contact with the inner peripheral surface of the emergency bearing and the rotary shaft is at the highest position. After the continuous change step,
While gradually increasing the current flowing through the plurality of coils disposed below among the plurality of coils, gradually decreasing the current flowing through the plurality of coils disposed above, with the rotation axis as the center of rotation. The method for starting a rotating machine according to claim 1, further comprising a position moving step of moving.

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