阅读说明：本技术 负载运转控制系统 (Load operation control system ) 是由 中泽勇二 阪胁笃 于 2018-05-08 设计创作，主要内容包括：驱动轴(20)驱动负载进行旋转。驱动支承部(50)借助通过规定的电流范围内的电流在该驱动支承部(50)中流动而产生的电磁力来驱动驱动轴(20)进行旋转,并且以非接触的形式支承驱动轴(20)的径向载荷。控制部(91a)基于由在驱动支承部(50)产生的总磁通量与在驱动支承部(50)中预先决定的总磁通极限量之差所表示的磁通余裕度,来控制负载的运转。总磁通量包括在负载的规定的运转区域中为了驱动驱动轴(20)进行旋转而在驱动支承部(50)产生的驱动用磁通、以及为了支承驱动轴(20)的径向载荷而在驱动支承部(50)产生的支承用磁通。(The drive shaft (20) rotates the load. The drive support section (50) drives the drive shaft (20) to rotate by means of electromagnetic force generated by the flow of current in a predetermined current range through the drive support section (50), and supports the radial load of the drive shaft (20) in a non-contact manner. The control unit (91a) controls the operation of the load on the basis of a magnetic flux margin represented by the difference between the total magnetic flux generated by the drive support unit (50) and the total magnetic flux limit amount predetermined in the drive support unit (50). The total magnetic flux includes a drive magnetic flux generated in the drive support portion (50) for driving the drive shaft (20) to rotate in a predetermined operating region of the load, and a support magnetic flux generated in the drive support portion (50) for supporting a radial load of the drive shaft (20).)

1. A load operation control system, comprising:

A drive shaft (20) that drives a load to rotate;

A drive support unit (50) that rotationally drives the drive shaft (20) by means of an electromagnetic force generated by a current flowing through the drive support unit (50) within a predetermined current range, and that contactlessly supports a radial load of the drive shaft (20); and

and a control unit (91a) that controls the operating conditions of the load on the basis of a magnetic flux margin represented by the difference between the total magnetic flux, which includes the drive magnetic flux generated in the drive support unit (50) to drive the drive shaft (20) to rotate in a predetermined operating region of the load, and the total magnetic flux limit amount predetermined in the drive support unit (50), and the support magnetic flux generated in the drive support unit (50) to support the radial load of the drive shaft (20).

2. The load operation control system according to claim 1,

The drive support section (50) has at least one bearingless motor (60, 70), and the bearingless motor (60, 70) has a pair of rotors (61, 71) and stators (64, 74), and drives the drive shaft (20) to rotate and supports the radial load of the drive shaft (20) in a non-contact manner.

3. The load operation control system according to claim 2,

The control unit (91a) calculates, as the total magnetic flux, a magnetic flux in a plurality of slots formed in the stator (64, 74) in which a total value of the drive magnetic flux and the support magnetic flux is maximized.

4. The load operation control system according to claim 3,

The control unit (91a) calculates the total magnetic flux by using, as the sum, the sum of the drive magnetic flux and the support magnetic flux and the magnetic flux of the permanent magnets (63, 73) of the rotors (61, 71).

5. The load operation control system according to any one of claims 1 to 4,

the load is a turbo compressor (1), the turbo compressor (1) compresses a refrigerant in a refrigerant circuit (110) that performs a refrigeration cycle,

When the magnetic flux margin exceeds a predetermined value, the control unit (91a) operates at least one of the rotational speed of the turbo compressor (1) and the flow rate of the refrigerant so as to increase the temperature of the refrigerant discharged from the turbo compressor (1),

When the magnetic flux margin is less than the predetermined value, the control unit (91a) operates at least one of the rotational speed of the turbocompressor (1) and the flow rate of the refrigerant so as to reduce the temperature of the refrigerant discharged from the turbocompressor (1).

6. The load operation control system according to claim 5,

The load operation control system further includes an updating unit (91b) that updates the predetermined operation region based on an operation state of the turbo compressor (1) when the control unit (91a) increases the temperature of the refrigerant discharged from the turbo compressor (1).

7. The load operation control system according to any one of claims 1 to 4,

The load is a turbo compressor (1), the turbo compressor (1) compresses a refrigerant in a refrigerant circuit (110) that performs a refrigeration cycle,

When the magnetic flux margin exceeds a predetermined value, the control unit (91a) operates at least one of the rotational speed of the turbo compressor (1) and the flow rate of the refrigerant so as to reduce the output of an air conditioning apparatus (100) having the refrigerant circuit (110),

When the magnetic flux margin is less than the predetermined value, the control unit (91a) operates at least one of the rotational speed of the turbo compressor (1) and the flow rate of the refrigerant so as to increase the output of the air conditioning device (100).

8. The load operation control system according to claim 7,

The load operation control system further comprises an update unit (91b),

The update unit (91b) updates the predetermined operating range based on the operating state of the turbo compressor (1) when the control unit (91a) decreases the output of the air conditioning device (100).

Technical Field

The present invention relates to a system for controlling an operating condition of a load connected to a drive shaft in a configuration in which the drive shaft is rotatably driven by a drive support portion and is supported in a non-contact manner.

Background

Among the compressors is sometimes referred to as a turbocompressor. Turbo compressors are used in various applications such as air conditioners.

In the turbo compressor, as disclosed in patent document 1, there is a technical problem of surging (surging). Surge refers to the phenomenon: for example, when the load of the compressor during operation suddenly changes from a high load to no load, the flow rate of the fluid (refrigerant) in the entire flow path including the compressor becomes unstable, the compressor and the pipes constituting the flow path resonate, and the pressure and the flow rate fluctuate periodically. Surge causes not only instability of the operating state of the compressor but also breakage of the compressor.

Disclosure of Invention

The technical problem to be solved by the invention

Surging occurs when the operating state of the compressor enters the surge region. In contrast, in patent document 1, the control is performed as follows: the operating state of the compressor is prevented from entering a surge region by suppressing a rapid decrease in flow rate before and after a transition in the load state of the compressor.

That is, the compressor of patent document 1 is operated only in the steady operation region. Therefore, in patent document 1, the use of the compressor is limited, and the range of operation possible of the compressor is narrowed.

The problem of limited use is not limited to compressors, but can occur similarly to pumps and other pumps that generate surge.

The present invention has been made in view of the above-described circumstances, and an object thereof is to expand the operating range of a load such as a compressor, which is likely to cause surging.

Technical solution for solving technical problem

A first aspect of the present disclosure is a load operation control system, including: a drive shaft 20 that drives a load to rotate; a driving support unit 50 that rotationally drives the driving shaft 20 by an electromagnetic force generated by a current flowing through the driving support unit 50 in a predetermined current range, and that contactlessly supports a radial load of the driving shaft 20; and a control unit 91a that controls an operating condition of the load based on a flux margin represented by a difference between a total magnetic flux, which includes a drive magnetic flux generated in the drive support unit 50 to drive the drive shaft 20 to rotate in a predetermined operating region of the load and a support magnetic flux generated in the drive support unit 50 to support a radial load of the drive shaft 20, and a total magnetic flux limit amount predetermined in the drive support unit 50.

Here, by changing the operating conditions of the load in accordance with the margin of magnetic flux of the driving support portion 50, the operating region of the load can be enlarged as much as possible. Specifically, when the operating region of the load is expanded from the steady-state operating region to the region where the rotating stall occurs, the radial load may be increased, but the control unit 91a changes the operating conditions of the load in accordance with the margin of magnetic flux of the drive support unit 50, and therefore the operating region can be expanded to the maximum controllable extent.

A second aspect of the present disclosure is, in addition to the first aspect, characterized in that the drive support portion 50 has at least one bearingless motor 60, 70, and the bearingless motor 60, 70 has a pair of rotors 61, 71 and stators 64, 74, and drives the drive shaft 20 to rotate and supports the radial load of the drive shaft 20 in a non-contact manner.

The bearingless motors 60 and 70 can change the ratio of the supporting magnetic flux and the driving magnetic flux according to, for example, the operating state of the load and the magnetic flux margin. That is, when the operating region of the load is expanded, control such as reducing the drive magnetic flux generated in the bearingless motors 60 and 70 and increasing the support magnetic flux can be performed within a range in which a constant magnetic flux margin is secured, so that the surge can be tolerated. Therefore, the load can be operated without any problem in a more various operating states.

A third aspect of the present disclosure is the second aspect, wherein the controller 91a calculates, as the total magnetic flux, a magnetic flux in a groove that maximizes a total value of the drive magnetic flux and the support magnetic flux, among the plurality of grooves formed in the stators 64 and 74.

In a fourth aspect of the present disclosure, in the third aspect of the present invention, the control unit 91a calculates the total magnetic flux by adding the magnetic flux of the permanent magnets 63 and 73 included in the rotors 61 and 71 to the driving magnetic flux and the supporting magnetic flux as the total value.

This makes it possible to more accurately grasp the total magnetic flux generated in the bearingless motors 60 and 70.

A fifth aspect of the present disclosure is directed to any one of the first to fourth aspects of the invention, wherein the load is a turbo compressor 1, the turbo compressor 1 compresses a refrigerant in a refrigerant circuit 110 performing a refrigeration cycle, the controller 91a operates at least one of a rotation speed of the turbo compressor 1 and a flow rate of the refrigerant so as to increase a temperature of the refrigerant discharged from the turbo compressor 1 when the flux margin exceeds a predetermined value, and the controller 91a operates at least one of the rotation speed of the turbo compressor 1 and the flow rate of the refrigerant so as to decrease the temperature of the refrigerant discharged from the turbo compressor 1 when the flux margin is less than the predetermined value.

When the magnetic flux margin exceeds the predetermined value, it can be determined that there is a margin in the drive support portion 50 from the viewpoint of magnetic flux. In this case, the head (compression work) of the turbo compressor 1 can be increased by increasing the temperature of the refrigerant discharged from the turbo compressor 1. The turbo compressor 1 can be operated even in a region where the head pressure is high means that the refrigerant circuit 110 can perform a refrigeration cycle even in a high-temperature outdoor environment, for example, and this means that the operation region of the load is expanded.

On the other hand, when the magnetic flux margin is less than the predetermined value, it can be determined that the driving support portion 50 has no margin from the viewpoint of magnetic flux. In this case, the head (compression work) of the turbo compressor 1 is reduced by lowering the temperature of the refrigerant discharged from the turbo compressor 1. This can prevent the occurrence of surge and rotating stall in the turbo compressor 1.

A sixth aspect of the present disclosure is the load operation control system according to the fifth aspect, further comprising an updating unit 91b that updates the predetermined operation region based on an operation state of the turbocompressor 1 when the control unit 91a increases the temperature of the refrigerant discharged from the turbocompressor 1.

As a result, the turbocompressor 1 can be operated with the expanded operating region as a reference at the next operation.

A seventh aspect of the present disclosure is directed to any one of the first to fourth aspects of the invention, wherein the load is a turbo compressor 1, the turbo compressor 1 compresses a refrigerant in a refrigerant circuit 110 performing a refrigeration cycle, the controller 91a operates at least one of a rotation speed of the turbo compressor 1 and a flow rate of the refrigerant so as to decrease an output of an air conditioner 100 having the refrigerant circuit 110 when the flux margin exceeds a predetermined value, and the controller 91a operates at least one of the rotation speed of the turbo compressor 1 and the flow rate of the refrigerant so as to increase the output of the air conditioner 100 when the flux margin is less than the predetermined value.

The lower the output of the air conditioner 100, the more easily the turbo compressor 1 enters the surge region, whereas the higher the output of the air conditioner 100, the more difficult the turbo compressor 1 enters the surge region.

Therefore, when the magnetic flux margin exceeds the predetermined value and there is a margin in the drive support portion 50 from the viewpoint of magnetic flux, the margin portion that consumes magnetic flux when the supporting magnetic flux is generated can be controlled, and therefore, the output of the air conditioning apparatus 100 is reduced to actively shift the operating state of the turbocompressor 1 to a region where rotating stall and surge occur. This means that the operating region of the load is enlarged.

If the magnetic flux margin is less than the predetermined value and the drive support portion 50 has no margin from the viewpoint of magnetic flux, the output of the air conditioning apparatus 100 is increased because the magnetic flux consumed when the support magnetic flux is generated is insufficient, and the turbocompressor 1 is operated in a region where entry into a region where rotating stall or surge is difficult to occur is achieved. This can prevent the occurrence of surge and rotating stall in the turbo compressor 1.

An eighth aspect of the present disclosure is, in the seventh aspect, characterized in that the load operation control system further includes an updating unit 91b that updates the predetermined operation region based on an operation state of the turbo compressor 1 when the control unit 91a lowers the output of the air conditioner 100.

As a result, the turbocompressor 1 can be operated with the expanded operating region as a reference at the next operation.

Effects of the invention

according to the aspect of the present disclosure, the operation region of the load is expanded to the controllable maximum, and therefore, the load driven by the driving support portion 50 can be operated in more various operation states.

Drawings

fig. 1 is a piping system diagram of an air conditioner.

Fig. 2 is a diagram showing a configuration example of the compressor.

Fig. 3 is a transverse sectional view showing a configuration example of the first bearingless motor.

Fig. 4 is a transverse cross-sectional view of the first bearingless motor, showing the magnet flux and the drive flux.

Fig. 5 is a transverse cross-sectional view of the first bearingless motor, showing the magnet flux and the supporting flux.

Fig. 6 is a transverse cross-sectional view of the first bearingless motor, showing the magnet magnetic flux, the drive magnetic flux, and the support magnetic flux.

Fig. 7 is a transverse cross-sectional view of the second bearingless motor, showing the magnet magnetic flux, the drive magnetic flux, and the support magnetic flux.

Fig. 8 is a diagram for explaining an operation region of the turbo compressor.

Fig. 9 is a diagram for explaining the expansion control of the operating range.

Fig. 10 is a diagram for explaining a mechanism of generating surge.

Fig. 11 is a diagram illustrating an operation flow of the operation region expansion control according to the first embodiment.

Fig. 12 is a diagram illustrating an operation flow of the operation region expansion control according to the second embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its application objects, or its uses.

First embodiment

Hereinafter, an example in which a compressor having a magnetic bearing device is used in an air conditioner will be described.

< integral Structure >

Fig. 1 is a piping diagram of an air conditioner 100 according to a first embodiment of the present invention. As shown in the drawing, the air conditioner 100 is an apparatus for conditioning indoor air, and has a refrigerant circuit 110 that is a closed circuit filled with a refrigerant. The refrigerant circuit 110 is configured by connecting the turbo compressor 1, the condenser 120, the expansion valve 130, and the evaporator 140 by refrigerant pipes. In the turbo compressor 1 according to the first embodiment, the bearingless motors 60 and 70 are driven.

The refrigerant circuit 110 is also provided with a sensor for detecting the refrigerant pressure and a sensor for detecting the refrigerant temperature, which are not shown.

In the first embodiment, the condenser 120 and the evaporator 140 are configured to exchange heat between the refrigerant and the aqueous medium. That is, the air conditioner 100 according to the first embodiment is a so-called cooling device that cools the room with an aqueous medium.

Specifically, the condenser 120 is connected to not only the refrigerant circuit 110 but also an outdoor-side water circuit 150 through which a water medium circulates. In the condenser 120, the refrigerant radiates heat to the aqueous medium (circulating water) of the outdoor-side water circuit 150 circulating from the outside, cools itself, and condenses. The aqueous medium flowing out of the condenser 120 dissipates heat outdoors.

The evaporator 140 is connected to not only the refrigerant circuit 110 but also an indoor-side water circuit 160 through which a water medium circulates. In the evaporator 140, the refrigerant absorbs heat from the aqueous medium (circulating water) in the indoor-side water circuit 160 circulating from the indoor space, and evaporates itself. The aqueous medium flowing out of the evaporator 140 circulates through an indoor-side water circuit provided in the room to cool the room.

< Structure of turbo compressor >

Fig. 2 shows a configuration example of the turbo compressor 1 according to the first embodiment. As shown in fig. 2, the turbo compressor 1 includes a casing 2, a compression mechanism 3, a drive shaft 20, protective bearings 30, 31, a thrust magnetic bearing 40, and a drive support portion 50.

The drive shaft 20, the protective bearings 30 and 31, the thrust magnetic bearing 40, and the drive support portion 50 are also components of the load operation control device 10 corresponding to a load operation control system, together with a controller 90 and the like described later. First, the case 2 and the compression mechanism 3 will be explained.

In the following description, the "axial direction" is a rotation axis direction and is a direction of an axial center of the drive shaft 20. "radial" is a direction orthogonal to the axial direction of the drive shaft 20. The "outer peripheral side" is a side farther from the axial center of the drive shaft 20, and the "inner peripheral side" is a side closer to the axial center of the drive shaft 20.

-a housing-

The housing 2 is formed in a cylindrical shape with both ends closed, and is disposed such that the cylindrical axis faces in the horizontal direction. The space in the casing 2 is partitioned by the wall portion 2a, and the space on the right side of the wall portion 2a constitutes an impeller chamber S1 for housing the impeller 3a of the compression mechanism 3, and the space on the left side of the wall portion 2a constitutes a motor chamber S3 for housing the first bearingless motor 60 and the second bearingless motor 70 included in the load operation control device 10. The drive shaft 20 extending in the axial direction in the casing 2 connects the impeller 3a to the first bearingless motor 60 and the second bearingless motor 70.

Thereby, the drive shaft 20 can rotationally drive the impeller 3a of the turbo compressor 1.

-compression means-

The compression mechanism 3 is configured to compress a fluid (a refrigerant in this example), and mainly includes an impeller 3 a. The impeller 3a is formed to have a substantially conical outer shape by a plurality of blades. The impeller 3a is housed in the impeller chamber S1 in a state of being connected and fixed to one end of the drive shaft 20. The suction pipe 4 and the discharge pipe 5 are connected to the impeller chamber S1, and a compression space S2 is formed in the outer peripheral portion of the impeller chamber S1. The suction pipe 4 is provided to guide the refrigerant from the outside into the impeller chamber S1, and the discharge pipe 5 is provided to return the high-pressure refrigerant compressed in the impeller chamber S1 to the outside.

< construction of load operation control device >

the load operation control device 10 is a device for controlling the operation of the impeller 3a of the turbo compressor 1. As described above, the load operation control device 10 includes the protection bearings 30 and 31, the thrust magnetic bearing 40, the drive support unit 50 including the first bearingless motor 60 and the second bearingless motor 70, the controller 90, and the power supply unit 93 in addition to the drive shaft 20.

Protection of the bearings

The protection bearings 30 and 31 are provided at two positions in the axial direction of the drive shaft 20 so as to sandwich the two bearingless motors 60 and 70. One protective bearing 30 is provided near one end portion (right-side end portion in fig. 2) of the drive shaft 20, and the other protective bearing 31 is provided near the other end portion of the drive shaft 20. These protective bearings 30 and 31 are configured to support the drive shaft 20 when the first bearingless motor 60 and the second bearingless motor 70 are not energized (i.e., when the drive shaft 20 is not floating).

Thrust magnetic bearing

As shown in fig. 2, the thrust magnetic bearing 40 includes a first electromagnet 41 and a second electromagnet 42, and is configured to support a disc-shaped portion (hereinafter, the disc portion 21) provided at the other end portion of the drive shaft 20 (i.e., the end portion opposite to the one end portion to which the impeller 3a is fixed) in a non-contact manner by electromagnetic force. The thrust magnetic bearing 40 can control the position of the supported portion (the disc portion 21) of the drive shaft 20 in the facing direction (i.e., the axial direction, the left-right direction in fig. 2) of the first electromagnet 41 and the second electromagnet 42 by controlling the current flowing to the first electromagnet 41 and the second electromagnet 42.

Note that, although not shown in fig. 2, a plurality of gap sensors are provided in the vicinity of the protective bearings 30 and 31 and the vicinity of the thrust magnetic bearing 40. The gap sensor is constituted by, for example, an eddy current type displacement sensor, and detects a gap between the disc portion 21 and the thrust magnetic bearing 40 and a gap between the stators 64 and 74 and the rotors 61 and 71 in the first bearingless motor 60 and the second bearingless motor 70. The detection result of the gap sensor is input to the controller 90 for various controls.

Driving the bearing

The drive support portion 50 drives the drive shaft 20 to rotate by an electromagnetic force generated by a current flowing in a predetermined current range, and supports a radial load of the drive shaft 20 in a non-contact manner. As described above, the drive support 50 includes the first bearingless motor 60 and the second bearingless motor 70. The first bearingless motor 60 and the second bearingless motor 70 are arranged side by side along the axial direction of the drive shaft 20.

A first bearingless motor

The first bearingless motor 60 is disposed in the motor chamber S3 on a side close to the impeller 3 a. The first bearingless motor 60 has a pair of rotors 61 and a stator 64. The rotor 61 is fixed to the drive shaft 20, and the stator 64 is fixed to the inner peripheral wall of the housing 2.

Fig. 3 is a transverse sectional view showing a configuration example of the first bearingless motor 60. As shown in the drawing, the first bearingless motor 60 is a bearingless motor of a Consequent pole (consequential pole) type. The stator 64 of the first bearingless motor 60 includes a back yoke 65, a plurality of teeth not shown, driving coils 66a to 66c wound around the teeth, and supporting coils 67a to 67 c. The rotor 61 of the first bearingless motor 60 has a core 62 and a plurality of (four in this example) permanent magnets 63 embedded in the core 62.

The stator 64 is made of a magnetic material (for example, laminated steel plates). The back yoke portion 65 of the stator 64 is formed in a cylindrical shape. The driving coils 66a to 66c and the supporting coils 67a to 67c are wound around the respective teeth in a distributed coil manner. Thereby, a plurality of slots (not shown) are formed in the stator 64. The drive coils 66a to 66c and the support coils 67a to 67c may be wound around the respective teeth in a concentrated winding manner.

The driving coils 66a to 66c are coils wound around the inner circumference of the teeth. The driving coils 66a to 66c include a U-phase driving coil 66a surrounded by a thick line, a V-phase driving coil 66b surrounded by a thick broken line, and a W-phase driving coil 66c surrounded by a thin line in fig. 3.

The support coils 67a to 67c are coils wound around the outer periphery of the teeth. The support coils 67a to 67c include a U-phase support coil 67a surrounded by a thick line, a V-phase support coil 67b surrounded by a thick broken line, and a W-phase support coil 67c surrounded by a thin line in fig. 3.

The core 62 of the rotor 61 is formed in a cylindrical shape. A shaft hole (not shown) for inserting the drive shaft 20 is formed in the center of the core 62. The core 62 is made of a magnetic material (e.g., laminated steel plate). In the vicinity of the outer peripheral surface of the core 62, four permanent magnets 63 extending along the outer peripheral surface are embedded, and the permanent magnets 63 are embedded at an angular pitch AP1 of 90 ° in the circumferential direction of the rotor 61. The four permanent magnets 63 have the same shape as each other. The outer peripheral surface side of each permanent magnet 63 is an N-pole, and the outer peripheral surface of the core 62 between the permanent magnets 63 is a pseudo S-pole. The outer peripheral surface side of each permanent magnet 63 may be an S-pole.

Fig. 4 shows a magnet magnetic flux Φ 1 generated by each permanent magnet 63 in the first bearingless motor 60, and a drive magnetic flux BM1 generated to drive the impeller 3a and the drive shaft 20 to rotate. The first bearingless motor 60 is configured to generate a driving torque T1 (i.e., a torque for rotating the drive shaft 20 in the counterclockwise direction in fig. 4) shown in the figure by the interaction between the magnet magnetic flux Φ 1 and the driving magnetic flux BM 1. In the figure, a current IM1 equivalent to the current flowing through the drive coils 66a to 66c is shown.

Fig. 5 shows a magnet magnetic flux Φ 1 generated by each permanent magnet 63 in the first bearingless motor 60 and a supporting magnetic flux BS1 generated to support the radial load of the drive shaft 20 in a non-contact manner. The first bearingless motor 60 is configured to generate a supporting force F1 (i.e., a force that pushes the drive shaft 20 in the right direction in fig. 5) shown in the figure by the interaction between the magnet magnetic flux Φ 1 and the supporting magnetic flux BS 1. In the figure, a current IS1 equivalent to the current flowing through the support coils 67a to 67c IS shown.

As can be seen from fig. 5, the magnetic path of the supporting magnetic flux BS1 is a path passing through the back yoke 65 and the teeth of the stator 64, the air gap, and the core 62 of the rotor 61. The magnetic resistance of the back yoke 65, the tooth portion, and the core 62 is smaller than that of the permanent magnet 63. Therefore, the magnetic resistance of the magnetic circuit for generating the magnetic force for supporting the radial load of the drive shaft 20 of the first bearingless motor 60 is smaller than that of the second bearingless motor 70 in which the permanent magnet 73 is arranged substantially over the entire outer peripheral surface of the rotor 71 (that is, the second bearingless motor 70 in which the permanent magnet 73 is included in the magnetic circuit for generating the magnetic force for supporting the radial load of the drive shaft 20) as described later. Therefore, the first bearingless motor 60 can generate a larger supporting force for supporting the radial load of the drive shaft 20 than the second bearingless motor 70.

Fig. 6 shows a magnet magnetic flux Φ 1 generated by each permanent magnet 63 in the first bearingless motor 60, a drive magnetic flux BM1 generated to drive the impeller 3a and the drive shaft 20 to rotate, and a support magnetic flux BS1 generated to support the radial load of the drive shaft 20 in a non-contact manner. The first bearingless motor 60 is configured to generate the driving torque T1 and the supporting force F1 shown in the figure at the same time by the interaction of the magnet magnetic flux Φ 1, the driving magnetic flux BM1, and the supporting magnetic flux BS 1. In the figure, currents IM1 and IS1 equivalent to the currents flowing through the driving coils 66a to 66c and the supporting coils 67a to 67c are shown.

A second bearingless motor

as shown in fig. 2, the second bearingless motor 70 is disposed on the side of the motor chamber S3 away from the impeller 3 a. As shown in fig. 7, the second bearingless motor 70 has a pair of rotors 71 and a stator 74. The rotor 71 is fixed to the drive shaft 20, and the stator 74 is fixed to the housing 2.

The second bearingless motor 70 is the same as that shown in fig. 3, and therefore, although not shown, a plurality of grooves are formed by winding a driving coil and a supporting coil around a plurality of teeth of the stator 74.

Fig. 7 is a transverse sectional view showing a structural example of the second bearingless motor 70. As shown in the drawing, the second bearingless motor 70 is an embedded magnet type bearingless motor which operates substantially in the same manner as the surface magnet type bearingless motor. The structure of the stator 74 of the second bearingless motor 70 is the same as the structure of the stator 64 of the first bearingless motor 60. The rotor 71 of the second bearingless motor 70 has a core portion 72 and a plurality of (eight in this example) permanent magnets 73 embedded in the core portion 72.

The core 72 of the rotor 71 is formed in a cylindrical shape. A shaft hole (not shown) for inserting the drive shaft 20 is formed in the center of the core 72. The core 72 is made of a magnetic material (e.g., laminated steel plate). In the vicinity of the outer peripheral surface of the core portion 72, eight permanent magnets 73 extending along the outer peripheral surface are embedded, and the permanent magnets 73 are embedded at an angular pitch AP2 of 45 ° in the circumferential direction of the rotor 71 (i.e., half of the angular pitch AP1 of 90 ° in the first bearingless motor 60). The eight permanent magnets 73 have the same shape as each other, and also have the same shape as the four permanent magnets 63 of the first bearingless motor 60. On the outer circumferential surface side of each permanent magnet 73, N poles and S poles appear alternately in the circumferential direction of the rotor 71.

Fig. 7 shows a magnet magnetic flux Φ 2 generated by each permanent magnet 73 in the second bearingless motor 70, a drive magnetic flux BM2 generated to drive the impeller 3a and the drive shaft 20 to rotate, and a support magnetic flux BS2 generated to support the radial load of the drive shaft 20 in a non-contact manner. The second bearingless motor 70 is configured to simultaneously generate a driving torque T2 (i.e., a torque for rotating the drive shaft 20 in the counterclockwise direction in fig. 7) and a supporting force F2 (i.e., a force for pushing the drive shaft 20 in the right direction in fig. 7) shown in the figure by the interaction of the magnet magnetic flux Φ 2, the driving magnetic flux BM2, and the supporting magnetic flux BS 2.

As can be seen from fig. 7, the magnetic path of the supporting magnetic flux BS2 is a path passing through the back yoke 75 and the teeth of the stator 74, the air gap, and the permanent magnet 73 and the core 72 of the rotor 71.

On the other hand, the number of the permanent magnets 73 in the second bearingless motor 70 is larger than the number of the permanent magnets 63 in the first bearingless motor 60. Therefore, the magnetic flux density of the magnetic flux generated by the permanent magnet 73 is higher in the first bearingless motor 70 than in the first bearingless motor 60 (see fig. 4). Therefore, the second bearingless motor 70 can generate a larger driving torque T2 for driving the impeller 3a and the drive shaft 20 to rotate than the first bearingless motor 60.

A controller

The controller 90 is composed of a microcomputer 91 and a memory 92 in which software and the like for operating the microcomputer 91 are stored. The controller 90 generates and outputs a voltage command value (thrust voltage command value) for controlling the voltage supplied to the thrust magnetic bearing 40 and a voltage command value (motor voltage command value) for controlling the voltage supplied to the first bearingless motor 60 and the second bearingless motor 70 so that the position of the drive shaft 20 becomes a desired position.

In the above-described generation operation of the voltage command value, a detection value of a gap sensor (not shown) capable of detecting a gap between the disc portion 21 and the thrust magnetic bearing 40, a detection value of a gap sensor (not shown) capable of detecting a gap between the stators 64, 74 and the rotors 61, 71 in the first bearingless motor 60 and the second bearingless motor 70, information of a target rotation speed of the impeller 3a and the drive shaft 20, and the like are used.

In particular, the microcomputer 91 of the controller 90 according to the first embodiment functions as an operation control unit 91a (corresponding to a control unit). The operation control unit 91a calculates a margin of total magnetic flux (hereinafter, a magnetic flux margin) in the first bearingless motor 60 and the second bearingless motor 70, and controls the operation conditions of the turbo compressor 1 (specifically, the impeller 3a of the compression mechanism 3) which are the loads of the first bearingless motor 60 and the second bearingless motor 70, based on the calculated magnetic flux margin. This operation control is a control for expanding the operation region of the turbo compressor 1, and will be described in detail later.

The microcomputer 91 of the controller 90 according to the first embodiment also functions as an update unit 91 b. The memory 92 stores a predetermined operating area (described later) composed of a plurality of areas, and the update unit 91b overwrites the predetermined operating area in the memory 92 when the predetermined operating area is updated.

-power supply section-

The power supply unit 93 supplies a voltage to the thrust magnetic bearing 40 and the first and second bearingless motors 60 and 70, respectively, based on the thrust voltage command value and the motor voltage command value from the controller 90. For example, the power supply unit 93 may be formed of a pwm (pulse Width modulation) amplifier.

< operating region of turbo compressor >

The operation region of the turbo compressor 1 will be described with reference to fig. 8. In fig. 8, the horizontal axis shows the refrigerant volume flow rate, and the vertical axis shows the head pressure. The turbocompressor 1 can be operated in a predetermined operation region by passing a current within a predetermined current range of the power supply unit 93 to the driving support unit 50 (the first bearingless motor 60 and the second bearingless motor 70 in the present first embodiment).

The predetermined operating region mainly includes a steady-state operating region a inside the surge line, a high-load torque region B and a turbulent flow region C, and a surge region D outside the surge line, which are indicated by the dashed-dotted line in fig. 8.

The steady-state operation region a is a region indicated by reference sign a in fig. 8, and is a region in which the load torque of the impeller 3a and the drive shaft 20 (i.e., the drive torques T1, T2 for driving the impeller 3a and the drive shaft 20 to rotate) is relatively small and the radial load of the drive shaft 20 is also relatively small.

The high load torque region B is a region indicated by reference symbol B in fig. 8, in which the load torque of the impeller 3a and the drive shaft 20 is relatively large and the radial load of the drive shaft 20 is also relatively large.

The turbulent flow region C is indicated by reference symbol C in fig. 8, and is a region in which the load torque ratio of the impeller 3a and the drive shaft 20 is small and the radial load ratio of the drive shaft 20 is large.

The surge region D is a region indicated by reference sign D in fig. 8, and is a region in which the load-torque ratio between the impeller 3a and the drive shaft 20 is small and the radial load ratio of the drive shaft 20 is large. The radial load of the drive shaft 20 in the turbo compressor 1 becomes maximum at a predetermined point in the surge region D. When the turbocompressor 1 is operated at the predetermined point, the value of the supporting magnetic flux BS is maximized, and the total maximum supporting force current flows to the supporting coils 67a to 67c of the bearingless motors 60 and 70.

Hereinafter, the case where the turbocompressor 1 is operated in the steady-state operation region a and the high load torque region B is referred to as "during normal operation", and the normal operation region a and the load torque region B are collectively referred to as "first operable region". In the present embodiment, the "first operable region" is set to a preset so-called default region. In addition, the turbulent flow region C is also referred to as "region where rotating stall occurs".

< processing for calculating Total flux margin >

How the operation control unit 91a calculates the flux margin will be described in detail.

The operation control unit 91a obtains the total magnetic flux generated in each bearingless motor 60, 70. The operation control unit 91a subtracts the calculated total magnetic flux from the predetermined total magnetic flux limit amount of each bearingless motor 60, 70, and thereby calculates a magnetic flux margin represented by the difference (subtraction result) between them.

As described above, the magnetic fluxes generated in the first bearingless motor 60 and the second bearingless motor 70 include the driving magnetic fluxes BM1 and BM2 generated in the first bearingless motor 60 and the second bearingless motor 70, respectively, for driving the impeller 3a and the drive shaft 20 to rotate in the predetermined operation region of the turbo compressor 1 shown in fig. 8; supporting magnetic fluxes BS1 and BS2 generated in the first bearingless motor 60 and the second bearingless motor 70, respectively, to support the radial load of the drive shaft 20 in a non-contact manner; and magnet fluxes Φ 1 and Φ 2 generated by the permanent magnets 63 and 73. First, the operation control unit 91a calculates the magnetic flux in the slot in which the total value of the drive magnetic fluxes BM1 and BM2, the support magnetic fluxes BS1 and BS2, and the magnet magnetic fluxes Φ 1 and Φ 2 becomes the maximum among all the slots (not shown) formed in the stators 64 and 74, for each of the bearingless motors 60 and 70.

Specifically, when the magnetic flux of the driving magnetic fluxes BM1 and BM2 is "Φ M", the magnetic flux of the supporting magnetic fluxes BS1 and BS2 is "Φ S", and the magnetic flux of the magnet magnetic fluxes Φ 1 and Φ 2 is "Φ P", the magnetic flux Φ n of the n-th slot at a certain moment is shown below.

[ mathematical formula 1]

Φ_n＝Φ_Mn+Φ_Sn+Φ_Pn＝Φ_Mn(i_M，θ_M，θ_R)+Φ_sn(i_S，θ_S，θ_R)+Φ_pn(θ_R)...(1)

Wherein each parameter is an instantaneous value. "iM" in the above equation is a drive equivalent current (a current equivalent to a current flowing through the drive coil), and is a parameter that contributes to the overall strength of the drive magnetic fluxes BM1 and BM 2. "iS a support equivalent current (current equivalent to the current flowing through the support coil), and iS a parameter contributing to the overall strength of the support magnetic fluxes BS1 and BS 2. "θ M" is an electrical angle of the driving magnetic fluxes BM1 and BM2, and is a parameter that contributes to the magnetic resistance of each slot of the driving magnetic fluxes BM1 and BM 2. "θ S" is an electrical angle of the supporting magnetic fluxes BS1 and BS2, and is a parameter that contributes to the magnetic resistance of each slot of the supporting magnetic fluxes BS1 and BS 2. "θ R" is the rotor electrical angle and is a parameter that contributes to the magnetic reluctance.

As a result of the expansion of (1), the magnetic flux Φ n of the nth slot at a certain moment is shown below.

[ mathematical formula 2]

"NM" in the above equation is the number of turns of the drive coils 66a to 66c in each bearingless motor 60, 70. "NS" is the number of turns of the support coils 67a to 67c in each bearingless motor 60, 70. "RMn" is a magnetic resistance of the driving magnetic fluxes BM1 and BM2 in the nth slot of each bearingless motor 60 and 70. "RSn" is the magnetic resistance of the supporting magnetic fluxes BS1, BS2 in the nth slot of each bearingless motor 60, 70. "RPn" is the magnetic resistance of the permanent magnet 63, 73 in the nth groove in each bearingless motor 60, 70. "FP" is the magnetomotive force of the permanent magnets 63, 73 in the respective bearingless motors 60, 70.

As described above, the maximum total magnetic flux Φ Max between the grooves in the bearingless motors 60 and 70 (the total magnetic flux corresponding to the magnetic flux generated by the drive support portion 50) is as follows.

[ mathematical formula 3]

If the predetermined total magnetic flux limit amount of each bearingless motor 60, 70 is Φ ULim, the magnetic flux margin M Φ of each bearingless motor 60, 70 is shown below.

[ mathematical formula 4]

M_Φ＝Φ_ULim-Φ_Max...(4)

Therefore, the flux margin M Φ is expressed by the following equations (3) and (4).

[ math figure 5]

The total flux limit Φ ULim is an inherent value determined by, for example, material characteristics of the bearingless motors 60 and 70.

In the following description, as an example, the total value of the magnetic flux margins M Φ of the bearingless motors 60 and 70 obtained based on the above expression (5) is used for the operation control of the compression mechanism 3.

< control action of bearingless Motor based on magnetic flux margin >

Control of the expansion of the operating zone

fig. 9 is a diagram for explaining the expansion control of the operating range. In fig. 9, the horizontal axis shows the output of the air conditioner 100, and the vertical axis shows the temperature of the aqueous medium flowing into the condenser 120 in the outdoor-side water circuit 150. The horizontal axis "output of the air conditioner" in fig. 9 is a parameter relating to the horizontal axis "refrigerant volume flow rate" in fig. 8. The output of the air conditioner 100 specifically represents: the heat per unit time (temperature condition of the aqueous medium) taken from the aqueous medium by the evaporator 140 of the air-conditioning apparatus 100 of fig. 1. The vertical axis "temperature of the aqueous medium flowing into the condenser" in fig. 9 is a parameter related to the vertical axis "head pressure" in fig. 8.

In fig. 9, a range surrounded by a broken line, a vertical axis, and a horizontal axis corresponds to a predetermined "first operable region" including the normal operation region a and the high-load torque region B of fig. 8. In fig. 9, the range sandwiched between the surge line indicated by the one-dot chain line and the boundary line of the first operable region indicated by the broken line corresponds to the turbulent flow region C of fig. 8, i.e., "the region where rotating stall is generated". In fig. 9, the region above the surge line indicated by the one-dot chain line corresponds to the surge region D in fig. 8.

Here, surge will be explained. Fig. 10 is a diagram for explaining a mechanism for generating surge. The turbocompressor 1 (in particular the impeller 3a) is designed to have the following properties: when the rotation speed is constant, the lower the volume flow rate of the refrigerant flowing into the turbo compressor 1, the higher the head pressure. In the predetermined first operable region of fig. 10, if the refrigerant volume flow rate increases due to external disturbance, the head pressure decreases. A reduction in head means a reduction in ejection pressure. On the other hand, if the refrigerant volume flow rate decreases due to external disturbance, the head pressure increases (that is, the discharge pressure increases), and the refrigerant volume flow rate becomes relatively stable.

However, if the volumetric flow rate of the refrigerant is further reduced in a state where the rotational speed of the turbo compressor 1 (specifically, the impeller 3a) is constant, the angle (attack angle) of the blades of the impeller 3a with respect to the refrigerant flow becomes excessively large, and a stall phenomenon occurs in some of the blades. This phenomenon is called "rotating stall" (turbulent region C in fig. 10) because it occurs in a rotating manner so as to propagate between the blades of the impeller 3 a. At the time of rotating stall, the pressure distribution near the impeller 3a becomes uneven, and a pulsating exciting force is applied to the impeller 3 a.

Further, when the refrigerant volume flow rate becomes extremely small in a state where the rotation speed is constant, the head pressure substantially converges to a fixed value (that is, the gradient of the head pressure with respect to the refrigerant volume flow rate approaches zero), and therefore, the stabilization of the refrigerant volume flow rate described above is impaired (surge region D in fig. 10). In this way, the refrigerant volume flow rate in the entire flow path from the evaporator 140 to the condenser 120 in the refrigerant circuit 110 becomes very unstable, and a larger pulsating exciting force is transmitted to the impeller 3 a. This phenomenon is "surge". This exciting force causes vibration of the turbo compressor 1, and the operation of the turbo compressor 1 becomes unstable. This exciting force causes an excessive load to be applied to the mechanical components constituting the turbo compressor 1, and in the worst case, the mechanical components are damaged.

Therefore, normally, as described using fig. 9, the first operational region set in advance is set in a region inside the surge line and other than the turbulent flow region C (specifically, the steady-state operation region a and the high-load torque region B) so as not to generate such surge.

When the turbo compressor 1 is operated near the boundary of the predetermined first operable region, for example, the power supply from the commercial power supply (not shown) to the air conditioner 100 is suddenly interrupted due to a power failure, and surging may occur. When the power supply to the air conditioner 100 is cut off, the operation of the turbo compressor 1 is also stopped. As a result, the refrigerant volume flow rate is rapidly decreased in a state where the head pressure of the turbo compressor 1 is not changed much, and then the head pressure of the turbo compressor 1 is also decreased. This is because, during a period from when the refrigerant volume flow rate sharply decreases to when the head pressure of the turbocompressor 1 decreases, the operating state of the turbocompressor 1 may temporarily transition from the predetermined first operable region to the surge region D beyond the surge line.

In contrast, when it is determined that the total magnetic flux of the first bearingless motor 60 and the second bearingless motor 70 has a margin with respect to the total magnetic flux limit amount based on the magnitude of the magnetic flux margin of the first bearingless motor 60 and the second bearingless motor 70, the operation control unit 91a according to the first embodiment controls the operating conditions of the turbocompressor 1 as the load so that the turbocompressor 1 is operated particularly in the turbulent flow region C. That is, the operation control unit 91a enlarges the region in which the operation of the turbocompressor 1 is permitted from the predetermined first operable region (lower part of the broken line in fig. 9) to the "second operable region" obtained by adding the portion of the "operation enlarged region" indicated by the oblique line in fig. 9 to the first operable region.

The operation region enlargement means that the turbo compressor 1 is operated at a point closer to the surge line than within the predetermined first operable region. Therefore, although the operating state of the turbocompressor 1 temporarily exceeds the surge line and the possibility of transition to the surge region D also increases, the operation control unit 91a according to the first embodiment performs control such that the turbocompressor 1 can sufficiently withstand rotating stall and surge in addition to the expansion of the operating region described above.

Specifically, the operation control unit 91a uses the margin of the total magnetic flux of the first bearingless motor 60 and the second bearingless motor 70 for generating the supporting force of the drive shaft 20, based on the magnetic flux margin of the first bearingless motor 60 and the second bearingless motor 70. As described above, each bearingless motor 60, 70 can generate the driving magnetic fluxes BM1, BM2 and the supporting magnetic fluxes BS1, BS2, and the operation control unit 91a generates and outputs the voltage command value (motor voltage command value) for causing the margin of the total magnetic flux of the first bearingless motor 60 and the second bearingless motor 70 to be used when the supporting magnetic fluxes BS1, BS2 are generated, but not used when the driving magnetic fluxes BM1, BM2 are generated.

Specifically, when the turbocompressor 1 IS operated in the turbulent flow region C, the operation control unit 91a transmits the motor voltage command value to the power supply unit 93 such that the ratio of the current IS for generating the supporting magnetic flux BS to the current IM for generating the driving magnetic flux BM (i.e., the sum BM1+ BM2 of the driving magnetic fluxes generated by the first bearingless motor 60 and the second bearingless motor 70) (i.e., the sum of the currents flowing through the supporting coils 67a to 67C of the first bearingless motor 60 and the second bearingless motor 70) IS increased as compared to that in the normal operation when the motor voltage command value IS compared at the same rotation speed. At this time, the power supply unit 93 supplies a voltage to the first bearingless motor 60 and the second bearingless motor 70 so as to increase the ratio of the current IS flowing to the supporting coils 67a to 67c to the current IM flowing to the driving coils 66a to 66c in the first bearingless motor 60 and the second bearingless motor 70, based on the motor voltage command value transmitted from the operation control unit 91 a.

As a result, in the turbulent flow region C (i.e., the rotating stall region), the supporting force of the drive shaft 20 is generated in the first bearingless motor 60 and the second bearingless motor 70 to such an extent that the exciting force can withstand rotating stall (and hence surge). Therefore, damage to the mechanical components constituting the turbo compressor 1 due to rotating stall and surge can be suppressed. Therefore, such control of expanding the operating region enables the turbocompressor 1 to be used in the operating region (the operating expanded region in fig. 9) which has been controlled so far to be used in particular in order to avoid the occurrence of rotating stall and surge, and therefore the range of the case of using the turbocompressor 1 is expanded.

Operation flow of expansion control of the operation region

The operation flow of the above-described operation region expansion control will be described below with reference to fig. 11.

First, the operation control unit 91a determines whether or not the expansion control of the operation region is permitted (step St 11). The availability of the expansion control of the operation region can be set appropriately by, for example, a constructor or who installs the air conditioner 100, a user, or the like.

if the expansion control of the operation region is not permitted (no at step St11), the operation controller 91a sets the output of the air conditioner 100 and the temperature of the aqueous medium flowing into the condenser 120 to values at which the turbo compressor 1 operates in the first operable region (step St 12). That is, in this case, the operation region is not expanded, and the turbocompressor 1 is operated in the predetermined first operable region in fig. 9 and 10.

When the expansion control of the operation region is permitted (yes at step St11), the operation control unit 91a estimates the current total magnetic flux in the first bearingless motor 60 and the second bearingless motor 70 by calculation based on the above expression (3) (step St 13). Then, the operation control unit 91a calculates the total magnetic flux margin of the first bearingless motor 60 and the second bearingless motor 70 based on the above expression (5) (step St 14). The operation control unit 91a compares the calculated total margin with a predetermined value (step St 15).

when the calculated total flux margin is equal to or greater than the predetermined value (yes at step St15), the operation controller 91a performs control for raising the temperature (discharge temperature) of the refrigerant discharged from the turbo compressor 1 on at least one of the constituent devices of the turbo compressor 1 and the refrigerant circuit 110 so that the output of the air conditioner 100 is constant and the temperature of the aqueous medium flowing into the condenser 120 is raised from the current water temperature (St 16). The calculated total magnetic flux margin is equal to or greater than the predetermined value, which means that there is a margin in the magnetic flux that can be generated by the first bearingless motor 60 and the second bearingless motor 70. When the indoor space is cooled, when the outdoor temperature rises, the temperature of the water flowing into the condenser 120 rises, and accordingly, the refrigerant temperature of the condenser 120 also rises and the refrigerant pressure also rises. At this time, even when the aqueous medium on the indoor side is cooled to a constant temperature (that is, the output of the air conditioner 100 is constant) at all times regardless of the outdoor temperature, the operation controller 91a performs control of adjusting at least one of the rotational speed of the turbo compressor 1 and the flow rate of the refrigerant in the refrigerant circuit 110 so that the discharge pressure of the turbo compressor 1 is increased to increase the discharge temperature of the refrigerant. For example, the operation control unit 91a increases the rotational speed of the turbo compressor 1 and/or decreases the flow rate of the refrigerant so that the discharge pressure of the turbo compressor 1 increases and the discharge temperature of the refrigerant increases.

The discharge pressure rise of the turbo compressor 1 is equivalent to the head rise of the turbo compressor 1. That is, step St16 in fig. 11 means that the operation region of the turbocompressor 1 is expanded from the predetermined first operable region in fig. 9 to the second operable region to which the operation expanded region portion is added. Step St16 in fig. 11 means that the limit operating point of the turbocompressor 1 transitions from a point (triangular mark in fig. 9) near the boundary line of the predetermined first operable region to an operating point (circular mark in fig. 9) that is changed in the direction in which the amount of magnetic flux used increases. In step St16, as the operating range expands, the margin of magnetic flux is used to generate the supporting magnetic fluxes BS1 and BS2 of the first bearingless motor 60 and the second bearingless motor 70, thereby increasing the drive supporting force of the drive shaft 20 and the impeller 3a included in the compression mechanism 3.

After step St16, the update unit 91b resets the predetermined operating region currently stored in the memory 92 with the predetermined operating region after the operating region is expanded at step St16 (step St 17). In other words, in the next operation region expansion control, a predetermined operation region including the expanded second operable region is used as a default value.

When the calculated total flux margin is less than the predetermined value (no at step St15), the operation controller 91a performs control for lowering the temperature (discharge temperature) of the refrigerant discharged from the turbo compressor 1 on at least one of the constituent devices of the turbo compressor 1 and the refrigerant circuit 110 so that the output of the air conditioner 100 is constant and the temperature of the aqueous medium flowing into the condenser 120 is lowered from the current water temperature (St 18). The calculated total magnetic flux margin is lower than the predetermined value, which means that there is no margin in the magnetic flux that can be generated in the first bearingless motor 60 and the second bearingless motor 70. Then, the operation control unit 91a performs control for adjusting at least one of the rotation speed of the turbo compressor 1 and the flow rate of the refrigerant in the refrigerant circuit 110 so that the discharge pressure of the turbo compressor 1 is reduced and the discharge temperature of the refrigerant is reduced. For example, the operation control unit 91a decreases the rotation speed of the turbo compressor 1 and/or increases the flow rate of the refrigerant so that the temperature of the refrigerant discharged from the turbo compressor 1 decreases. In this case, the head pressure is reduced, and therefore, the operation region of the turbo compressor 1 is not expanded.

< effects >

In the first embodiment, by changing the operating conditions of the turbocompressor 1 in accordance with the margin of magnetic flux for driving the support portion 50, the operating region of the turbocompressor 1 can be expanded to the maximum controllable extent. Specifically, the operation control unit 91a performs control of a margin portion consuming magnetic flux when the supporting magnetic flux is generated in a region where the rotating stall occurs, based on the magnetic flux margin for driving the supporting portion 50. Therefore, the turbocompressor 1 can be operated without any problem not only in the first operable region of fig. 9 but also in a region where rotating stall occurs (turbulent region C, i.e., an operation-expanded region). Therefore, the operation can be performed in more various operation states.

In particular, the drive support portion 50 includes a first bearingless motor 60 and a second bearingless motor 70. These bearingless motors 60 and 70 can change the ratio of the supporting magnetic flux and the driving magnetic flux according to the operating state of the load and the magnetic flux margin. That is, when the operating region of the turbocompressor 1 is expanded, control such as reducing the drive magnetic flux generated in each bearingless motor 60, 70 and increasing the support magnetic flux can be performed within a range in which a constant magnetic flux margin is secured, so that the surge phenomenon can be tolerated. Therefore, the turbo compressor 1 can be operated without any problem in more various operating states.

The operation control unit 91a calculates, as the total magnetic flux, the magnetic flux in the groove in which the total value of the magnet fluxes Φ 1 and Φ 2 of the permanent magnets 63 and 73 of the driving magnetic fluxes BM1 and BM2, the supporting magnetic fluxes BS1 and BS2, and the rotors 61 and 71 is the maximum, among the plurality of grooves formed in the stators 64 and 74. This makes it possible to accurately grasp the total magnetic flux generated in the bearingless motors 60 and 70, and therefore, the operation region can be expanded to the maximum extent while maintaining the control accuracy of the driving support unit 50 without causing magnetic saturation.

As shown in step St16 of fig. 11, when the magnetic flux margin exceeds the predetermined value, the operation control unit 91a increases the temperature of the aqueous medium flowing into the condenser 120 by increasing the head (compression work) of the turbocompressor 1 (that is, by increasing the temperature of the refrigerant discharged from the turbocompressor 1) because it can be determined that there is a margin in the drive support unit 50 from the viewpoint of magnetic flux. The temperature rise of the aqueous medium flowing into the condenser 120 means that the refrigerant circuit 110 can perform a refrigeration cycle even in a high-temperature outdoor environment, for example, and this means that the operating range of the load is expanded.

On the other hand, as shown in step St18 of fig. 11, when the magnetic flux margin is less than the predetermined value, the operation control unit 91a reduces the temperature of the refrigerant discharged from the turbocompressor 1 to reduce the head pressure (compression work) of the turbocompressor 1 because it can be determined from the viewpoint of magnetic flux that there is no margin in the drive support unit 50. This can prevent the occurrence of surge and rotating stall in the turbo compressor 1.

As shown in step St17 of fig. 11, the update unit 91b updates the predetermined operation region based on the operation state of the turbo compressor 1 when the control unit 91a increases the temperature of the refrigerant discharged from the turbo compressor 1. As a result, the turbocompressor 1 can be operated with the expanded operating region as a reference at the next operation.

Second embodiment

In the first embodiment, as shown in steps St16 and St18 in fig. 11, the output of the air conditioner 100 is made constant in the control for lowering the temperature (discharge temperature) of the refrigerant based on the margin of magnetic flux. In the second embodiment, unlike the first embodiment, the output of the air conditioner 100 is changed in the control for lowering the temperature (discharge temperature) of the refrigerant based on the flux margin.

In the second embodiment, only a part of the operation flow of the operation region expansion control shown in fig. 12 is different from that shown in fig. 11 of the first embodiment, and the configuration of the turbocompressor 1, the air-conditioning apparatus 100, and the load operation control device 10 is the same as that of the first embodiment. Therefore, only the differences between fig. 12 and fig. 11 will be described below.

Operation flow of expansion control of the operation region

steps St11 to St15 in fig. 12 are the same as those in fig. 11.

In step St15 of fig. 12, when the calculated total flux margin is equal to or greater than the predetermined value (yes in step St15), the operation controller 91a adjusts at least one of the rotation speed of the turbo compressor 1 and the flow rate of the refrigerant flowing through the refrigerant circuit 110 so that the temperature of the aqueous medium flowing into the condenser 120 is constant and the output of the air-conditioning apparatus 100 is decreased (St 26).

After step St26, the update unit 91b resets the predetermined operating region currently stored in the memory 92 with the predetermined operating region after the operating region is expanded at step St26 (step St 27). In other words, in the next operation region expansion control, a predetermined operation region including the expanded second operable region is used as a default value.

When the total flux margin is less than the predetermined value (no at step St15), the operation controller 91a adjusts at least one of the rotation speed of the turbo compressor 1 and the flow rate of the refrigerant flowing through the refrigerant circuit 110 so that the temperature of the aqueous medium flowing into the condenser 120 is constant and the output of the air conditioner 100 is increased (St 28).

< effects >

Based on fig. 9, the lower the output of the air conditioner 100, the easier the turbocompressor 1 enters the turbulent flow region C. Conversely, the higher the output of the air conditioning apparatus 100, the more difficult it is for the turbocompressor 1 to enter the turbulent flow region C.

As in St26, when the magnetic flux margin exceeds the predetermined value and there is a margin in driving support unit 50 from the viewpoint of magnetic flux, control can be performed to consume the magnetic flux having the margin when supporting magnetic fluxes BS1 and BS2 are generated. Therefore, in the present second embodiment, the output of the air conditioner 100 is reduced, and the operating state of the turbo compressor 1 is actively transitioned to the turbulent flow region C. This means that the operating region of the load is enlarged.

on the other hand, if the magnetic flux margin is less than the predetermined value and there is no margin in driving support unit 50 from the viewpoint of magnetic flux, the magnetic flux consumed when supporting magnetic fluxes BS1 and BS2 are generated is insufficient. Therefore, in the present second embodiment, the output of the air conditioner 100 is increased, and it is difficult to make the operating state of the turbo compressor 1 transition to the turbulent flow region C. This can prevent the occurrence of surge and rotating stall in the turbo compressor 1.

Other embodiments

The load operation control device 10 can also be applied to the drive support unit 50 including, instead of the two bearingless motors 60 and 70, a radial magnetic bearing that generates a drive support force of the drive shaft and a rotary electric machine other than the bearingless motor that generates a rotational drive force of the drive shaft, in the drive support unit 50.

In addition, the load operation control device 10 can also be applied to the drive support portion 50 including one radial magnetic bearing and one bearingless motor.

When the drive support portion 50 is formed of a plurality of bearingless motors, the number of bearingless motors is not limited to two, and may be one, or may be three or more.

The kind of the bearingless motors 60, 70 is not limited to the consequent pole type and the like.

The bearingless motors 60 and 70 may be configured not to have a coil for driving and a coil for supporting, respectively, but to have a coil having both functions.

The rotors 61 and 71 and the stators 64 and 74 may be made of a material other than laminated steel plates.

The number of the impellers 3a of the turbo compressor 1 is not limited to one, and may be two or more. For example, one impeller may be installed at each end of the drive shaft 20.

The load of the load operation control device 10 may be any load that may cause surging. The load is not limited to the turbo compressor 1, and may be a pump or the like.

In the case of the bearingless motor having a structure without a permanent magnet, the total magnetic flux generated by the bearingless motors 60 and 70 is obtained from the total value of the driving magnetic flux Φ M and the supporting magnetic flux Φ S, without adding the magnet magnetic flux Φ P.

The method of calculating the flux margin using the above expressions (1) to (5) is an example. The method of calculating the flux margin may be a method other than the method using the above expressions (1) to (5). For example, the peak value of the flux margin M Φ at every predetermined time and/or the value obtained by low-pass filtering the flux margin M Φ may be set as the flux margin M Φ.

in the first and second embodiments described above, the case where the air conditioner 100 is a cooling device is exemplified, but the air conditioner 100 is not limited to the cooling device.

Although the predetermined operation region is updated in step St17 in fig. 11 and step St27 in fig. 12, steps St17 and St27 are not essential.

In steps St16 and St18 in fig. 11, a case is illustrated in which the output of the air conditioner 100 is made constant and the temperature of the aqueous medium flowing into the condenser 120 is changed from the current water temperature. However, instead of changing the temperature of the aqueous medium flowing into the condenser 120 from the current water temperature, the temperature of the aqueous medium flowing into the evaporator 140 may be changed from the current water temperature. Specifically, in step St16, the operation controller 91a may make the output of the air conditioner 100 constant, and lower the temperature of the aqueous medium flowing into the evaporator 140 from the current water temperature. In step St18, the operation controller 91a may increase the temperature of the aqueous medium flowing into the evaporator 140 from the current water temperature by keeping the output of the air conditioner 100 constant.

Industrial applicability-

As described above, the present invention is useful as a system for controlling the operation of a load in a configuration in which the load is a device that may cause surging and the drive support portion drives and rotates a drive shaft that drives the load and supports the drive shaft in a non-contact manner.

-description of symbols-

1 turbo compressor

10 load operation control device (load operation control system)

20 drive shaft

50 drive support

60 first bearingless motor

61 rotor

64 stator

70 second bearingless motor

71 rotor

74 stator

91a operation control part (control part)

91b update unit