Turbo compressor and turbo refrigerator equipped with same

Abstract

To provide a turbo compressor that can cool a magnetic bearing drive board at a proper temperature with a simple structure.SOLUTION: A turbo compressor 3 includes: an impeller for compressing refrigerant; a shaft part for rotating the impeller; an electric motor for rotatably driving the shaft part; a casing 12 for accommodating the electric motor; a cooling refrigerant supply part for leading cooling refrigerant into the casing 12; a magnetic bearing for supporting a radial direction and a thrust direction of the shaft part; and a magnetic bearing drive board 35 including an electronic component for driving the magnetic bearing. The magnetic bearing drive board 35 is fitted to an outer part of the casing 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a turbo compressor equipped with a magnetic bearing and a turbo chiller equipped with the same. [Background technology]

[0002] Centrifugal chillers are known that include a compressor in which an impeller is driven by an electric motor. Patent Documents 1 and 2 below disclose that this type of centrifugal chiller uses a refrigerant to cool the inverter that drives the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-149835 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-213670 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, magnetic bearings are sometimes used to support the shaft that rotates the impeller in the radial and thrust directions. A drive board equipped with electronic components that drive the magnetic bearing generates heat and must be cooled. A possible approach for cooling the drive board is to use a refrigerant, as in the above-mentioned patent documents. However, cooling with a refrigerant can result in excessive cooling, which can cause condensation on the electronic components. It is also possible to cool the drive substrate with a fan, but this poses the problem of requiring maintenance of the fan. Another option is to ensure a sufficient heat dissipation area and cool the drive substrate by natural convection, but this would result in an increased size of the structure.

[0005] The present disclosure has been made in consideration of these circumstances, and aims to provide a turbo compressor that has a simple structure and is capable of cooling a magnetic bearing drive substrate at an appropriate temperature, and a turbo chiller equipped with the same. [Means for solving the problem]

[0006] A turbo compressor according to one aspect of the present disclosure includes an impeller that compresses a refrigerant, a shaft that rotates the impeller, an electric motor that rotationally drives the shaft, a casing that houses the electric motor, a cooling refrigerant supply unit that introduces a cooling refrigerant into the casing, magnetic bearings that support the shaft in a radial direction and / or a thrust direction, and a magnetic bearing drive board that has electronic components that drive the magnetic bearing, the magnetic bearing drive board being attached to the outside of the casing.

[0007] The electric motor that drives the impeller of the turbo compressor is cooled by a cooling refrigerant that is guided into the casing. Accordingly, the casing that houses the electric motor is also cooled by the cooling refrigerant. A magnetic bearing drive board that drives a magnetic bearing is attached to the outside of this casing. This allows for appropriate cooling even for a magnetic bearing drive board that does not generate as much heat as the electric motor. Furthermore, because the casing is used as a heat sink, there is no need to provide a special cooling device to cool the magnetic bearing drive board, making it possible to achieve a simple and inexpensive structure. In particular, even if the magnetic bearing drive board is attached to the outside of the casing, the casing is not cooled as much as the electric motor, so it is possible to prevent condensation from forming on the magnetic bearing drive board.

[0008] Furthermore, in the turbo compressor according to one aspect of the present disclosure, the amount of heat generated by the magnetic bearing drive board is set to one-tenth or less of the amount of heat generated by the electric motor.

[0009] The heat generation amount of the magnetic bearing drive board is set to one-tenth or less of the heat generation amount of the electric motor, so by attaching it to the outside of the casing, it can be appropriately cooled. For example, the heat generation amount of the magnetic bearing drive board is set to be between 100 W and 300 W. More preferably, the heat generation amount of the magnetic bearing drive board is set to one-fifteenth or less of the heat generation amount of the electric motor. Also, for example, the heat generation amount of the magnetic bearing drive board is set to one-fortieth or more of the heat generation amount of the electric motor.

[0010] Furthermore, in the turbo compressor according to an aspect of the present disclosure, a gas refrigerant is supplied from the cooling refrigerant supply unit.

[0011] Because a gas refrigerant is supplied from the cooling refrigerant supply unit, there is no risk of excessive cooling compared to when a liquid refrigerant is supplied, and therefore it is possible to avoid as much as possible the magnetic bearing drive substrate being excessively cooled and causing condensation. In order to prevent the casing from being cooled excessively, a gas refrigerant may be used as the refrigerant for cooling the casing, and a liquid refrigerant may be supplied to the electric motor, which requires a large amount of cooling.

[0012] Furthermore, a turbo compressor according to an aspect of the present disclosure includes a cooling refrigerant adjustment valve that adjusts the flow rate of refrigerant supplied to the cooling refrigerant supply unit, a casing temperature sensor that measures the temperature of the casing, and a control unit that controls the cooling refrigerant adjustment valve based on an output of the casing temperature sensor. an electric motor coil temperature sensor that measures the temperature of a coil of the electric motor; and a magnetic bearing coil temperature sensor that measures the temperature of a coil of the magnetic bearing. The magnetic bearing drive substrate is attached to the outside of the casing, and the control unit controls the casing temperature so that the temperature does not fall below a casing temperature setting value that is determined so that the temperature of the casing does not fall to a temperature at which condensation occurs on the magnetic bearing drive substrate. Condensation suppression control Do The casing temperature setting value is determined based on the substrate ambient temperature obtained by a substrate ambient temperature sensor provided around the magnetic bearing drive substrate. and controlling the cooling refrigerant adjustment valve based on outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor, and the control based on outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor is given priority when the control conflicts with the condensation suppression control. .

[0013] The flow rate of the cooling medium is adjusted based on the casing temperature, which makes it possible to control the casing temperature so that it does not drop to a temperature at which condensation occurs on the magnetic bearing drive substrate.

[0014] Furthermore, a turbo compressor according to one aspect of the present disclosure includes an electric motor coil temperature sensor that measures the temperature of the coil of the electric motor, and a magnetic bearing coil temperature sensor that measures the temperature of the coil of the magnetic bearing, and the control unit controls the cooling refrigerant adjustment valve based on outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor.

[0015] The cooling refrigerant adjustment valve is controlled based on the outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor, which makes it possible to prevent condensation on the magnetic bearing drive board and prevent the electric motor and magnetic bearing from overheating.

[0016] A turbo chiller according to one aspect of the present disclosure includes any of the turbo compressors described above, a condenser that condenses refrigerant discharged from the turbo compressor, an expansion valve that expands liquid refrigerant guided from the condenser, and an evaporator that evaporates the refrigerant guided from the expansion valve. [Effects of the Invention]

[0017] Since the casing that houses the electric motor is used as a heat sink, the magnetic bearing drive substrate can be cooled to an appropriate temperature with a simple structure. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic configuration diagram illustrating a turbo chiller according to an embodiment of the present disclosure. FIG. [Figure 2] FIG. 2 is a side cross-sectional view showing the turbo compressor of FIG. 1. [Figure 3] FIG. 2 is a side view of the turbo compressor of FIG. 1. [Figure 4] FIG. 4 is a rear view of the turbo compressor of FIG. 3. [Figure 5]FIG. 2 is a schematic diagram showing a first modified example of FIG. [Figure 6] FIG. 2 is a schematic diagram showing a second modified example of FIG. [Figure 7] FIG. 2 is a schematic diagram showing a third modified example of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a turbo chiller 1. The turbo chiller 1 includes a turbo compressor 3 that compresses a refrigerant, a condenser 5 that condenses the high-temperature, high-pressure gas refrigerant compressed by the turbo compressor 3, an expansion valve 7 that expands the liquid refrigerant from the condenser 5, and an evaporator 9 that evaporates the liquid refrigerant expanded by the expansion valve 7.

[0020] The turbo compressor 3 is a centrifugal two-stage compressor equipped with two impellers 13a, 13b, and is driven by an electric motor 10 whose rotation speed is controlled by an inverter device (not shown). The inverter device has its output controlled by a control unit (not shown). The number of impellers is not limited, and a single-stage compressor with one impeller may also be used.

[0021] The refrigerant intake ports of the impellers 13a, 13b of the turbo compressor 3 are provided with inlet guide vanes (not shown) that control the flow rate of the intake refrigerant, making it possible to control the capacity of the turbo chiller 1.

[0022] The turbo compressor 3 and the electric motor 10 are housed in a hermetically sealed state within a casing 12. The casing 12 is made of a metal such as an aluminum alloy. The casing 12 can be opened and closed for maintenance and other purposes. In this way, the turbo compressor 3 is a semi-hermetic electric compressor housed together with the electric motor 10 within the casing 12, which can be hermetically opened and closed. Therefore, refrigerant can flow within the casing 12. Specifically, the refrigerant is supplied from the condenser 5 to the casing 12, for example, from above the casing 12, via a cooling refrigerant supply pipe (cooling refrigerant supply unit) 14. The cooling refrigerant supply pipe 14 is provided with a cooling refrigerant adjustment valve 16. The opening of the cooling refrigerant adjustment valve 16 is controlled by a control unit (not shown). After cooling the heat-generating components within the casing 12, the refrigerant is returned to the evaporator 9, for example, from below the casing 12 via a cooling refrigerant return pipe 18.

[0023] The electric motor 10 includes a rotor 20 that rotates around a central axis, and a generally cylindrical stator 22 that is provided around the rotor 20 with a predetermined gap. The rotational output of the rotor 20 is transmitted to the impellers 13a and 13b via a rotating shaft (shaft portion) 24.

[0024] The high-temperature, high-pressure refrigerant introduced from the turbo compressor 3 is condensed in the condenser 5. A cooling heat transfer pipe 26 through which cooling water flows for cooling the refrigerant is inserted into the condenser 5. The cooling water is guided back to the condenser 5 after its heat is discharged to the outside in a cooling tower (not shown).

[0025] The refrigerant throttled by the expansion valve 7 is introduced into the evaporator 9 and evaporates inside. Heat is absorbed in the evaporator 9 to obtain chilled water at a rated temperature (for example, 7°C). A chilled water heat transfer pipe 28 for cooling the chilled water to be supplied to an external load is inserted into the evaporator 9.

[0026] 2 shows a specific configuration of the turbo compressor 3. The rotating shaft 24 of the turbo compressor 3 is rotatably supported by a magnetic bearing 30. A first radial magnetic bearing coil 30a of the magnetic bearing 30 is provided on the impellers 13a, 13b side of the electric motor 10, and a second radial magnetic bearing coil 30b of the magnetic bearing 30 is provided on the opposite side of the electric motor 10 from the impellers 13a, 13b. The first radial magnetic bearing coil 30a and the second radial magnetic bearing coil 30b support the rotating shaft 24 in the radial direction.

[0027] The first radial magnetic bearing coil 30a is provided with a first coil temperature sensor Tc1 that measures the temperature of the first radial magnetic bearing coil 30a. The output of the first coil temperature sensor Tc1 is sent to the control unit. The second radial magnetic bearing coil 30b is provided with a second coil temperature sensor Tc2 that measures the temperature of the second radial magnetic bearing coil 30b. The output of the second coil temperature sensor Tc2 is sent to the control unit.

[0028] A first gap sensor G1 that measures the distance (gap) between the rotating shaft 24 and the first radial magnetic bearing coil 30a is provided on the electric motor 10 side of the first radial magnetic bearing coil 30a. The output of the first gap sensor G1 is sent to the control unit. A second gap sensor G2 that measures the distance (gap) between the rotating shaft 24 and the second radial magnetic bearing coil 30b is provided on the electric motor 10 side of the second radial magnetic bearing coil 30b. The output of the second gap sensor G2 is sent to the control unit.

[0029] A first auxiliary bearing 32a is provided between the first radial magnetic bearing coil 30a and the impellers 13a, 13b. A second auxiliary bearing 32b is provided on the opposite side of the second radial magnetic bearing coil 30b from the impellers 13a, 13b. The first auxiliary bearing 32a and the second auxiliary bearing 32b are, for example, ball bearings, and have a predetermined clearance with respect to the rotating shaft 24 when the magnetic bearing 30 is operating normally. These auxiliary bearings 32a, 32b come into contact with the rotating shaft 24 to rotatably support it when the magnetic bearing 30 is not operating due to a problem or the like.

[0030] A disk 24a is fixed to the end of the rotating shaft 24 opposite the impellers 13a and 13b (the left end in FIG. 2). Pairs of thrust magnetic bearing coils 30c are provided on both sides of the disk 24a. The disk 24a is positioned in the thrust direction while being levitated by the pairs of thrust magnetic bearing coils 30c. This allows the positions of the rotating shaft 24 and the impellers 13a and 13b in the thrust direction to be accurately determined. The thrust magnetic bearing coil 30c is provided with a third coil temperature sensor Tc3 that measures the temperature of the thrust magnetic bearing coil 30c. The output of the third coil temperature sensor Tc3 is sent to the control unit.

[0031] The stator 22 of the electric motor 10 is provided with a motor temperature sensor Tm1 that measures the coil end temperature of the stator 22. The output of the motor temperature sensor Tm1 is sent to the control unit. A casing temperature sensor Tcs1 that measures the temperature of the casing 12 is attached to the casing 12. The output of the casing temperature sensor Tcs1 is sent to the control unit. The cooling refrigerant supply pipe 14 is provided with a cooling refrigerant inlet temperature sensor Tin that measures the temperature of the refrigerant supplied into the casing 12. The output of the cooling refrigerant inlet temperature sensor Tin is sent to the control unit. The cooling refrigerant return pipe 18 is provided with a cooling refrigerant outlet temperature sensor Tout that measures the temperature of the refrigerant discharged to the outside of the casing 12. The output of the cooling refrigerant outlet temperature sensor Tout is sent to the control unit.

[0032] The control unit is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and computer-readable storage media. A series of processes for realizing various functions is stored in, for example, a storage medium in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0033] The control unit includes a magnetic bearing drive board 35 having electronic components for driving the magnetic bearing 30. The magnetic bearing drive board 35 receives, for example, outputs from the gap sensors G1 and G2, and outputs drive power to each of the magnetic bearing coils 30a, 30b, and 30c based on these output signals.

[0034] As shown in Figures 3 and 4, the magnetic bearing drive substrate 35 is fixed to the casing 12. Specifically, it is fixed to a flat portion 12a provided on the outer circumferential surface of the approximately cylindrical casing 12. The flat portion 12a is a flat surface and has a larger area than the magnetic bearing drive substrate 35. The flat portion 12a is formed on a wide surface of a block body 12b that is fixed integrally to the side circumferential surface of the casing 12. The block body 12b has an approximately rectangular parallelepiped shape and is used as a heat sink. The flat portion 12a may be formed by cutting part of the side circumferential surface of the casing 12 into a flat shape, or may be provided on the end surface of the approximately cylindrical casing 12.

[0035] The magnetic bearing drive substrate 35 is fixed so as to be in surface contact with the flat surface portion 12a. The flat surface portion 12a to which the magnetic bearing drive substrate 35 is attached may be polished or otherwise adjusted in surface roughness to improve thermal conductivity. Alternatively, thermal conductivity may be improved by applying grease or the like between the magnetic bearing drive substrate 35 and the flat surface portion 12a.

[0036] The heat generation amount of the magnetic bearing drive substrate 35 is, for example, 1 / 10 or less (preferably 1 / 15 or less) and 1 / 40 or more of the heat generation amount of the electric motor 10. More specifically, the heat generation amount of the magnetic bearing drive substrate 35 is, for example, 100 W or more and 300 W or less. In addition to the magnetic bearing drive board 35, electronic devices constituting other control units and boards on which these devices are mounted may also be fixed to the flat portion 12a.

[0037] A substrate ambient temperature sensor Tb1 is provided around the magnetic bearing drive substrate 35 to measure the ambient temperature of the magnetic bearing drive substrate 35. The output of the substrate ambient temperature sensor Tb1 is sent to the control unit.

[0038] <Operation of turbo chiller 1> Next, the operation of the turbo chiller 1 configured as described above will be described. The turbo compressor 3 sucks in the gas refrigerant from the evaporator 9 and compresses it with the impellers 13a and 13b. The compressed gas refrigerant is sent to the condenser 5 and condensed by the heat of condensation being removed by the cooling heat transfer tube 26. The liquid refrigerant after condensation flows to the expansion valve 7. The liquid refrigerant that flows to the expansion valve 7 is expanded by the expansion valve 7 and then sent to the evaporator 9. In the evaporator 9, the liquid refrigerant is evaporated by removing latent heat of evaporation from the cold water flowing inside the cold water heat transfer tube 28. The cold water cooled in this way is sent to an external load (not shown). The gas refrigerant that has evaporated in the evaporator 9 is sent again to the turbo compressor 3.

[0039] <Refrigerant cooling> Cooling by the refrigerant introduced into the casing 12 from the cooling refrigerant supply pipe 14 is carried out as follows. High-pressure liquid refrigerant is sent into the casing 12 via the cooling refrigerant supply pipe 14. At this time, the flow rate of the liquid refrigerant sent to the casing 12 is controlled by the cooling refrigerant adjustment valve 16, and the liquid refrigerant expands. The liquid refrigerant that has flowed into the casing 12 evaporates within the casing 12, thereby removing heat from the electric motor 10 and cooling the electric motor 10. At the same time, the casing 12 is also cooled by the refrigerant, and therefore the magnetic bearing drive board 35 attached to the flat portion 12a of the casing 12 is also cooled. The gas refrigerant that has finished cooling the electric motor 10 is returned via the cooling refrigerant return pipe 18 to the evaporator 9, which is kept at low pressure.

[0040] <Control of the cooling refrigerant adjustment valve 16> The cooling refrigerant adjusting valve 16 is controlled by the control unit as follows. The cooling refrigerant adjustment valve 16 is adjusted so that condensation does not occur on the magnetic bearing drive substrate 35. Specifically, the control unit performs PID control of the opening of the cooling refrigerant adjustment valve 16 so that the casing temperature obtained by the casing temperature sensor Tcs1 does not fall below the casing temperature set value. The casing temperature set value is determined based on the substrate ambient temperature obtained by the substrate ambient temperature sensor Tb1. In other words, the dew point is calculated from the temperature and humidity around the casing 12 at the substrate ambient temperature, and the casing temperature set value is determined based on this dew point. However, if the ambient environment of the casing 12 can be predicted in advance, the casing temperature set value may be uniquely determined for the substrate ambient temperature. For example, the casing temperature set value may be set to a temperature obtained by adding a predetermined temperature (e.g., 3°C) to the substrate ambient temperature.

[0041] The control unit also controls the aperture of the cooling refrigerant adjustment valve 16 so that the temperatures of the electric motor 10 and the magnetic bearing 30 are equal to or lower than predetermined values. That is, the control unit controls the aperture of the cooling refrigerant adjustment valve 16 so that the coil end temperature obtained by the motor temperature sensor Tm1 is equal to or lower than a set value, and so that the coil temperatures obtained by the coil temperature sensors Tc1, Tc2, and Tc3 of the magnetic bearing 30 are equal to or lower than a set value. This control is performed by adding to the valve aperture obtained by the control based on the casing temperature set value described above. Furthermore, when the various controls conflict with each other, the control based on the motor temperature sensor Tm1 and the coil temperature sensors Tc1, Tc2, and Tc3 is given priority as a protective control over the control performed on the casing temperature set value.

[0042] According to this embodiment, the following advantageous effects are achieved. The electric motor 10 that drives the impellers 13a, 13b of the turbo compressor 3 is cooled by the refrigerant that is guided into the casing 12. Accordingly, the casing 12 that houses the electric motor 10 is also cooled by the refrigerant. The magnetic bearing drive board 35 that drives the magnetic bearing 30 is attached to the outside of the casing 12. This makes it possible to appropriately cool the magnetic bearing drive board 35, even though the amount of heat generated is not as great as that of the electric motor 10. Furthermore, because the casing 12 is used as a heat sink, there is no need to provide a special cooling device to cool the magnetic bearing drive board 35, making it possible to achieve a simple and inexpensive structure. In particular, even if the magnetic bearing drive board 35 is attached to the outside of the casing 12, the casing 12 is not cooled as much as the electric motor 10, so that the magnetic bearing drive board 35 can be prevented from forming condensation.

[0043] The flow rate of the cooling refrigerant is adjusted based on the casing temperature obtained by the casing temperature sensor Tcs1, which makes it possible to control the casing temperature so that it does not drop to a temperature at which condensation occurs on the magnetic bearing drive substrate 35.

[0044] The opening of the cooling refrigerant adjustment valve 16 is controlled based on the outputs of the motor temperature sensor Tm1 and the coil temperature sensors Tc1, Tc2, and Tc3 of the magnetic bearing 30. This makes it possible to prevent condensation on the magnetic bearing drive board 35 while also preventing the electric motor 10 and magnetic bearing 30 from overheating.

[0045] This embodiment can be modified as follows. <Variation 1> As shown in Fig. 5, there are provided a cooling gas refrigerant supply pipe 37 that connects the gas phase part of the condenser 5 and the casing 12, and a cooling gas refrigerant return pipe 39 that connects the casing 12 and the gas phase part of the evaporator 9. A cooling gas refrigerant adjustment valve 38 is provided on the cooling gas refrigerant supply pipe 37. The cooling gas refrigerant adjustment valve 38 is driven by the control unit.

[0046] The gas refrigerant introduced into the casing 12 from the cooling gas refrigerant supply pipe 37 is supplied so as to flow toward the inner wall surface of the casing 12 where the magnetic bearing drive substrate 35 is located. This eliminates the risk of excessive cooling compared to when cooling is performed by supplying a liquid refrigerant, and therefore makes it possible to avoid as much as possible the magnetic bearing drive substrate 35 being excessively cooled and causing condensation. On the other hand, the liquid refrigerant introduced into the casing 12 from the cooling refrigerant supply pipe 14 does not flow toward the magnetic bearing drive board 35, but flows mainly to cool the electric motor 10 and the coils 30a, 30b, 30c of the magnetic bearing 30.

[0047] <Variation 2> As shown in Fig. 6, instead of the configuration shown in Fig. 1, a two-stage expansion refrigerant circuit having an economizer 40 may be used. A first expansion valve 7a is provided between the economizer 40 and the condenser 5, and a second expansion valve 7b is provided between the economizer 40 and the evaporator 9. An intermediate-pressure gas refrigerant pipe 42 is provided to connect the economizer 40 and the suction side of the second-stage impeller 13b. In this modification, the cooling refrigerant supply pipe 14a is configured to guide the liquid refrigerant from the economizer 40 to the casing 12.

[0048] <Variation 3> As shown in Fig. 7, in addition to the configuration shown in Fig. 6, a cooling gas refrigerant supply pipe 37 for supplying a cooling gas refrigerant may be provided as shown in Fig. 5. In this modification, the gas refrigerant is supplied into the casing 12 from the intercooler 40. [Explanation of symbols]

[0049] 1. Turbo Refrigerator 3. Turbo compressor 5. Condenser 7 Expansion valve 9. Evaporator 10 Electric motor 12 Casing 12a Flat part 12b block letters 13a, 13b impeller 14,14a Cooling refrigerant supply piping (cooling refrigerant supply section) 16 Cooling refrigerant regulating valve 18 Cooling refrigerant return pipe 20 rotors 22 Stator 24 Rotating shaft (shaft) 24a Disc 26 Cooling heat transfer tube 28 Cold water heat transfer tube 30 Magnetic bearings 30a First radial magnetic bearing coil 30b Second radial magnetic bearing coil 30c Thrust Magnetic Bearing Coil 32a 1st auxiliary bearing 32b Second auxiliary bearing 35 Magnetic bearing drive board 37 Cooling gas refrigerant supply piping 38 Cooling gas refrigerant regulating valve 39 Cooling gas refrigerant return pipe 40 Intercooler 42 Intermediate pressure gas refrigerant piping G1 First gap sensor G2 Second gap sensor Tb1 Board ambient temperature sensor Tc1 First coil temperature sensor (magnetic bearing coil temperature sensor) Tc2 Second coil temperature sensor (magnetic bearing coil temperature sensor) Tc3 Third coil temperature sensor (magnetic bearing coil temperature sensor) Tcs1 Casing Temperature Sensor Tin Coolant inlet temperature sensor Tm1 Motor temperature sensor (electric motor coil temperature sensor) Tout Cooling refrigerant outlet temperature sensor

Claims

1. an impeller that compresses the refrigerant; a shaft portion that rotates the impeller; an electric motor that rotates the shaft portion; a casing that houses the electric motor; a cooling refrigerant supply unit that introduces a cooling refrigerant into the casing; a magnetic bearing that supports the shaft portion in the radial direction and / or the thrust direction; a magnetic bearing drive substrate having electronic components for driving the magnetic bearing; a cooling refrigerant regulating valve that regulates the flow rate of the refrigerant supplied to the cooling refrigerant supply unit; a casing temperature sensor that measures the temperature of the casing; a control unit that controls the cooling refrigerant regulating valve based on an output of the casing temperature sensor; an electric motor coil temperature sensor that measures the temperature of the coil of the electric motor; a magnetic bearing coil temperature sensor that measures the temperature of the magnetic bearing coil; Equipped with the magnetic bearing drive substrate is attached to the outside of the casing, the control unit performs condensation suppression control so that the temperature of the casing does not fall below a casing temperature setting value that is determined so that the temperature of the casing does not fall to a temperature at which condensation occurs on the magnetic bearing drive substrate, The casing temperature setting value is determined based on a substrate ambient temperature obtained by a substrate ambient temperature sensor provided around the magnetic bearing drive substrate, and controlling the cooling refrigerant regulating valve based on outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor; The control based on the outputs of the electric motor coil temperature sensor and the magnetic bearing coil temperature sensor is prioritized when the control conflicts with the condensation suppression control.

2. 2. The turbo compressor according to claim 1, wherein the amount of heat generated by the magnetic bearing drive board is one-tenth or less of the amount of heat generated by the electric motor.

3. The turbo compressor according to claim 1 or 2, wherein a gas refrigerant is supplied from the cooling refrigerant supply portion.

4. A turbo compressor according to any one of claims 1 to 3; a condenser that condenses the refrigerant discharged from the turbo compressor; an expansion valve that expands the liquid refrigerant guided from the condenser; an evaporator that evaporates the refrigerant introduced from the expansion valve; A turbo refrigerator equipped with

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