Permanent magnet motor for centrifugal compressor and operation mode control method thereof

Abstract

The technology described and documented herein relates to a permanent magnet motor having multiple voltage taps such that the motor can be operated in multiple configurations, such as low range and high range, and the motor has multiple optimal operating points.

Description

Technical Field

[0001] The present disclosure generally relates to operating modes of centrifugal compressors for heating, ventilation, air conditioning, and refrigeration (HVACR) systems. Background Art

[0002] Centrifugal compressors are widely used in HVACR systems. Motors that operate such centrifugal compressors are designed for specific speed and torque conditions, and therefore component sizes may be affected by the operating current of the motor. For example, when the motor is operated under partial speed conditions, the corresponding voltage may be lower than the voltage under optimal speed conditions, while the corresponding current value may be higher than the current value under optimal speed conditions. Such limitations have hindered the development and / or deployment of HVACR systems that provide ecological and economic benefits. As the market demand for more energy- and cost-efficient solutions for dual-mode HVACR systems continues to grow, solutions are needed. Summary of the invention

[0003] According to at least one example embodiment, a permanent magnet motor for an HVACR system includes: a rotor; a voltage tap that can variably connect the rotor to any one of a low-range voltage path and a high-range voltage path; and a VFD that can variably connect to the rotor via the low-range voltage path or the high-range voltage path.

[0004] According to at least one other example embodiment, a method of controlling an operating mode of a permanent magnet motor in an HVACR system includes controlling a speed of a rotor corresponding to the permanent magnet motor by switching between a wye connection and a delta connection between the rotor and a VFD. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the following detailed description, the embodiments are described only as illustrations, since various changes and modifications will become apparent to those skilled in the art from the following detailed description. The same reference numerals are used in different drawings to indicate similar or identical items.

[0006] Figure 1 illustrates a heating, ventilation, air conditioning, and refrigeration (HVACR) system according to at least one example embodiment described and documented herein;

[0007] Figure 2 illustrates a schematic diagram of a permanent magnet motor according to at least one example embodiment described and documented herein;

[0008] Figure 3 illustrates a perspective view of a rotor according to at least one example embodiment described and documented herein;

[0009] Figure 4 illustrates a circuit representation of a motor 110 according to at least one example embodiment described and documented herein;

[0010] Figure 5 illustrates a schematic diagram of a multi-range permanent magnet motor according to at least one example embodiment described and recorded herein; and

[0011] Figure 6 A Y-connection and a delta-connection are illustrated according to at least one example embodiment described and documented herein. DETAILED DESCRIPTION

[0012] In the following detailed description, reference is made to the accompanying drawings that form a part of the specification. Unless the context indicates otherwise, similar symbols in the drawings generally identify similar parts. In addition, unless otherwise stated, the description of each consecutive figure may refer to the features of one or more figures from the previous figures to provide a clearer background and more substantial explanation of the current example embodiment. However, the example embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized and other changes may be made without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the various aspects of the present disclosure as generally described herein and illustrated in the drawings may be arranged, replaced, combined, separated, and designed in a variety of different configurations, all of which are expressly contemplated herein.

[0013] The scope of the present disclosure should be determined by the appended claims and their legal equivalents, rather than by the examples given herein. For example, the operations or functions recited in any method claim may be performed in any order and are not limited to the order presented in the corresponding claim. In addition, no element is essential to the practice of the present disclosure unless specifically described as such herein.

[0014] Described and documented herein are systems, devices, and methods that facilitate a dual-mode HVACR to switch motor voltage for heating and cooling modes, thereby extracting more power at common rated currents for each mode. As described and documented herein, a dual-mode HVACR may be considered a dual-mode (i.e., heating and cooling) device. Thus, the systems, devices, and methods described and / or documented herein relate to a motor having multiple switching connection points so that the motor can operate in multiple configurations (e.g., a low range and a high range), and the motor has multiple operating points for heating and cooling. According to at least one example embodiment, the motor may enable a VFD to have two connection points, thereby providing a variable voltage range.

[0015] Figure 1A heating, ventilation, air conditioning, and refrigeration (HVACR) system is illustrated in accordance with at least one example embodiment described and documented herein. The HVACR system 100 may be any suitable HVACR system for providing heating, ventilation, air conditioning, and / or refrigeration to one or more conditioned spaces. According to at least one example embodiment, the HVACR system 100 is a cooling unit, such as a centrifugal cooling unit, having a capacity between substantially 20 tons and substantially 500 tons or more.

[0016] A non-limiting example embodiment of the HVACR system 100 may include a compressor 105 , which may be driven by a motor 110 .

[0017] Non-limiting example embodiments of the compressor 105 may be any of a centrifugal compressor, a scroll compressor, a screw compressor, or other suitable types of compressors. For the present description, the compressor 105 may be considered a centrifugal compressor.

[0018] Figure 2 A schematic diagram of a permanent magnet motor is illustrated according to at least one example embodiment described and documented herein.

[0019] according to Figure 1 The motor 110 described may be a high speed permanent magnet motor.

[0020] The motor 110 may include a stator 205 and a rotor 210. The stator 205 may have an inner diameter ID, and the rotor 210 may have an outer diameter OD, wherein the difference between the inner diameter ID and the outer diameter OD is an air gap AG.

[0021] According to at least one non-limiting example embodiment, the motor 110 may be included in Figure 1 The centrifugal HVACR system shown.

[0022] The stator 205 may be configured to generate an electromagnetic torque for rotating the rotor 210. The stator 205 may include a core and a winding. The stator 205 may be configured to generate an electromagnetic torque for rotating the rotor 210. Figure 4 The variable frequency drive (VFD) shown and described draws power.

[0023] For example, the size of the rotor 210 may be based on modeling of the motor 110 when operating at full load, and / or modeling of the motor 110 when operating at part load. According to at least one example embodiment, the size of the rotor 210 may be designed to improve the integral part load value (IPLV) of a compressor including the motor 110. The IPLV may reflect the cost of operating the compressor when the compressor is at part load, thereby providing a cost function for such operation.

[0024] The air gap AG may be based at least in part on the rotor surface speed of the rotor 210. The rotor surface speed is a function of the diameter of the rotor 210 in the motor 110 and the designed rotational speed of the rotor 210. For example, in a high-speed motor embodiment where the surface speed of the rotor 210 is between 100 m / s and 200 m / s, the air gap AG may be, for example, between equal to or about 4.5 mm and equal to or about 7 mm. In a non-limiting example embodiment, the size of the air gap AG may be from equal to or about 5 mm to equal to or about 8 mm. The air gap AG determined based on the rotor surface speed may be a magnetic air gap based on the outermost magnetic component of the rotor 210 including any sleeve disposed on the rotor. The magnetic air gap may not include a non-magnetic portion of the sleeve, such as a carbon fiber composite portion.

[0025] Figure 3 Illustrated is a perspective view of a rotor 210 according to at least one example embodiment described and documented herein.

[0026] The rotor 210 is a surface permanent magnet (SPM) rotor for an electric motor. The rotor 210 may be configured to rotate by an electromagnetic torque provided by a stator of the electric motor. The rotation of the rotor 210 caused by the electromagnetic torque may be used to operate a device, such as a compressor. The rotor 210 may be incorporated into or merged into a drive shaft so that the drive shaft rotates by the operation of the electric motor using the rotor 210. For example, the drive shaft may be used to rotate an impeller, such as an impeller of a centrifugal compressor. The rotor 210 may be used, for example, in a closed or semi-closed centrifugal compressor used in a cooling unit and / or a heating, ventilation, air conditioning and refrigeration (HVACR) system having a capacity between 20 tons and 500 tons or more.

[0027] The rotor core 305 may be a portion of the rotor 210 toward the center of the rotor 210 .

[0028] The permanent magnet 315 may refer to a plurality of permanent magnets disposed on the rotor core 305. The permanent magnet 315 may be any suitable permanent magnet material, such as SmCo or NdFeB, etc., and the permanent magnet 315 may be radially distributed around the rotor core 305. The pole spacers 320 may also be disposed on the rotor core 305, arranged in the spaces between the permanent magnets 315.

[0029] The pole spacers 320 and the permanent magnets 315 in combination can define a plurality of magnetic poles that respond to the electromagnetic torque provided by the stator of the electric motor including the rotor 210. The pole spacers 320 can be any suitable material, such as stainless steel. The permanent magnets 315 and the pole spacers 320 can be adjacent to each other. According to at least one example embodiment, the permanent magnets 315 and the pole spacers 320 surround the rotor core 305, and the permanent magnets 315 and the pole spacers 320 can be included in any suitable number and configuration to provide magnetic poles that allow the rotation of the rotor 210.

[0030] A recess 325 may be formed in at least some of the pole spacers 320 and configured to accommodate a stud or a pin, etc. In at least some example embodiments, the engagement surface between the recess 325 and the protrusion 310 may also restrict the pole spacers 320 and / or the permanent magnets 315 from sliding in the axial direction of the rotor 210.

[0031] The retaining sleeve 330 is a sleeve that surrounds the rotor core 305, the permanent magnets 315, and the pole spacers 320. The retaining sleeve 330 can be any suitable material for retaining the permanent magnets 315 and the pole spacers 320. That is, the retaining sleeve 330 can slide over the permanent magnets 315 and the pole spacers 320. In at least one example embodiment, the retaining sleeve 330 is not press-fit onto the magnets 315 and the pole spacers 320. The interface between the recesses 325 and the retaining sleeve 330 can be the source of retaining the permanent magnets 315 and the pole spacers 320 to the rotor core 305.

[0032] Figure 4 A circuit representation of a motor 110 is illustrated according to at least one example embodiment described and documented herein.

[0033] The motor 110 may include a stator 205 , a rotor 210 , and a VFD 405 .

[0034] The stator 205 may include multiple switching connection points to enable the motor 110 to operate in multiple configurations (e.g., low range voltage and high range voltage) for multiple operating points. According to at least one example embodiment, the motor may have two connection points for a variable frequency drive (VFD), thereby providing a variable voltage range.

[0035] The stator 205 may draw power from the VFD 405 and is configured to generate electromagnetic torque to rotate the rotor 210. The stator 205 may include a plurality of voltage taps, switches 407A, 407B, 407C, arranged to achieve maximum VFD output voltage at a desired operating point of the dual mode HVACR system. Figure 4The non-limiting example embodiment of shows a three-phase motor and thus includes voltage taps 407A, 407B, and 407C. However, the embodiment of mode switching for a centrifugal compressor is not limited thereto with respect to the number of phases or the number of corresponding voltage taps. In addition, because the taps will be switched in a uniform manner with respect to each other in the disconnected state, reference will be made herein to voltage tap 407 unless the context requires otherwise.

[0036] The stator 205 may have voltage taps 407A, 407B, and 407C to variably connect the rotor 205 to corresponding low-range voltage paths 420A, 420B, 420C at a low range value of, for example, 230V, or to corresponding high-range voltage paths 425A, 425B, 425C at a high range value of, for example, 460V. That is, the high range may correspond to a grid voltage within a range of 400V, 460V, 575V, 690V, 3.3kV, or 4.16kV. Depending on how the corresponding windings of the stator 205 are tapped, the low voltage range may be a fixed portion of the high voltage range. For example, see Figure 5 , a four-pole motor with two winding branches in series in each phase can be tapped in the middle of the branch. Therefore, connecting to the tap can obtain about half the voltage of the tapped branch. Therefore, according to this example, the total voltage of one branch and half of the branch can be three quarters of the high voltage range.

[0037] Regardless, as explained above, due to the uniformity of the respective high-range voltage paths and low-range voltage paths, reference will be made herein to the high-range voltage path 425 and the low-range voltage path 420 unless the context requires otherwise.

[0038] According to the example embodiments described and documented herein, switching the voltage tap 407 with the VFD 405 via the high-range voltage path 425 provides sufficient output voltage and current to activate the dual-mode HVACR system as a cooling system for lower speeds; and switching the voltage tap 407 with the VFD 405 via the low-range voltage path 420 provides sufficient output voltage and current to activate the dual-mode HVACR system as a heating system for higher speeds. Thus, at least as Figure 4 As shown, the motor 110 is optimized for different operating points as a cooler and a heater. That is, the motor 110 has multiple connections so that the motor can be operated in more than one configuration (e.g., low range voltage and high range voltage), and the motor has more than one operating point. As an example, the stator 205 has a second voltage path to the VFD 405 that can be optimized for a heating mode that operates at a higher speed than for a cooling mode.

[0039] According to at least some of the example embodiments described and documented herein, mode switching is helpful in the off state. That is, the demand for heating or cooling is unlikely to change quickly, thereby avoiding the need to switch during operation of the motor 110. In addition, switching during operation of the motor 110 is prone to overcurrent.

[0040] According to at least some of the example embodiments described and documented herein, the VFD 405 can be motor tuned differently for operation in a refrigeration or cooling mode than for operation in a heating mode due to differences in inductance, resistance, and flux linkage in the low-range voltage path and the high-range voltage path. In addition, the pulse-width modulation (PWM) frequency and path can be optimized for the operating mode because, for example, the voltage tap for the low-range voltage path has a lower inductance than the inductance of the high-range voltage path and therefore operates at a higher PWM frequency.

[0041]

[0042] Figure 5 A schematic diagram of a multi-pole permanent magnet motor with some winding branches tapped according to at least one example embodiment described and documented herein is illustrated. As explained above, the motor 110 can be a high speed permanent magnet motor. According to a non-limiting example embodiment described and documented herein, the number of poles of the motor is a multiple of four (4), and thus four winding branches are connected in series.

[0043] That is to say, Figure 5 As shown in the non-limiting example embodiment of the invention, the multi-tap four-pole motor 500 has N poles 505A and 505B and S poles 510A and 510B. Unless the context requires otherwise, the description herein may refer to the N pole 505 and the S pole 510, taking into account the symmetry between the N poles 505A and 505B and the symmetry between the S poles 510A and 510B.

[0044] like Figure 5 As shown, winding branches 515A, 515B, 520A and 520B corresponding to N pole 505 and S pole 510 are arranged in series. Unless the context requires otherwise, the description herein may refer to N pole winding 515 and S pole winding 520, taking into account the symmetry between N pole windings and the symmetry between S pole windings.

[0045] Figure 6 A wye connection and a delta connection are illustrated according to at least one example embodiment described and documented herein.

[0046] The example embodiments described and documented herein relate to controlling the speed of a rotor corresponding to a permanent magnet motor by switching between a wye connection and a delta connection between the rotor and a VFD.

[0047] Wye and delta connections are typically used to reduce voltage when starting an induction motor and are therefore not typically used in conjunction with a permanent magnet motor as in the embodiments described and documented herein.

[0048] However, advantageously, in conjunction with the permanent magnet motors described and documented herein, a wye connection enables the motor to operate at lower speeds, whereby higher back EMF (electromotive force) corresponds to higher torque and lower current in operation, and a delta connection enables the motor to operate at higher speeds corresponding to lower back EMF. Typically, a delta connection requires (1 / √3) lower voltage, or about 58%, relative to a wye connection.

[0049] aspect:

[0050] It should be understood that any aspect of aspects 1 to 10 may be combined with any aspect of aspects 11 to 20 , and any aspect of aspects 1 to 10 and aspects 12 to 20 may be combined with aspect 11 .

[0051] Aspect 1. A permanent magnet motor for a heating, ventilation, air conditioning and refrigeration (HVACR) system, comprising:

[0052] Rotor;

[0053] a voltage tap capable of variably connecting the rotor to any one of a low-range voltage path and a high-range voltage path; and

[0054] A variable frequency drive (VFD) is variably connected to the rotor via the low-range voltage path or the high-range voltage path.

[0055] Aspect 2. The permanent magnet motor according to aspect 1, wherein the voltage tap connects the rotor to the VFD via the low-range voltage path to implement the HVACR system as a heating system.

[0056] Aspect 3. The permanent magnet motor according to any one of aspects 1 or 2, wherein the low-range path carries a voltage of 230V.

[0057] Aspect 4. The permanent magnet motor according to any one of aspects 1 to 3, wherein the low range voltage path carries a maximum VFD output voltage for a heating system.

[0058] Aspect 5. The permanent magnet motor of claim 1, wherein the voltage tap connects the rotor to the VFD via the high range voltage path to implement the HVAC system as a cooling system.

[0059] Aspect 6. The permanent magnet motor according to any one of aspects 1 to 5, wherein the high-range voltage path carries a voltage of 460V.

[0060] Aspect 7. The permanent magnet motor according to any one of aspects 1 to 6, wherein the high range voltage path carries a maximum VFD output voltage for a cooling system.

[0061] Aspect 8. The permanent magnet motor according to any one of aspects 1 to 7, wherein the permanent magnet motor is a multi-tap four-pole motor, wherein further, each pole has a corresponding coil branch, and the coil branches for four poles are connected in series.

[0062] Aspect 9. The permanent magnet motor according to any one of aspects 1 to 8, wherein the number of poles for the permanent magnet motor is a multiple of four, and wherein further each pole has a corresponding coil branch, and the coil branches for the poles are connected in series.

[0063] Aspect 10. The permanent magnet motor according to any one of aspects 1 to 9, wherein the low range voltage path is wye-connected to the VFD, and the high range voltage path is delta-connected to the VFD.

[0064] Aspect 11. A method of controlling an operating mode of a permanent magnet motor in a heating, ventilation, air conditioning and refrigeration (HVACR) system, the method comprising:

[0065] The speed of the rotor corresponding to the permanent magnet motor is controlled by switching between connections between the rotor and a variable frequency drive.

[0066] Aspect 12. A method of controlling an operating mode of a permanent magnet motor in a heating, ventilation, air conditioning and refrigeration (HVACR) system, the method comprising:

[0067] The speed of the rotor corresponding to the permanent magnet motor is controlled by switching between a wye connection and a delta connection between the rotor and a variable frequency drive (VFD).

[0068] Aspect 13. The method according to aspect 12, wherein the Y-connection is a high-range voltage path.

[0069] Aspect 14. The method of any of aspects 12 or 13, wherein the Y-connection provides power to the HVAC as a low speed cooling system.

[0070] Aspect 15. The method according to any one of aspects 12 to 14, wherein the delta connection is a low range voltage path.

[0071] Aspect 16. The method of any of aspects 12 to 15, wherein the delta connection provides power to the HVACR as a high speed heating system.

[0072] Aspect 17. The method according to any one of aspects 12 to 16, wherein the permanent magnet motor is a multi-tap four-pole motor, wherein further, each pole has a corresponding coil branch, and the coil branches for four poles are connected in series.

[0073] Aspect 18. The method according to any one of aspects 12 to 17, wherein the number of poles for the permanent magnet motor is a multiple of four, and wherein further each pole has a corresponding coil branch, and the coil branches for the poles are connected in series.

[0074] The foregoing description and subsequent description of the present disclosure are provided for the purpose of illustration, but not so limited. That is, various modifications can be made without departing from the scope and spirit of the present disclosure.

Claims

1. A permanent magnet motor for a heating, ventilation, air conditioning and refrigeration (HVACR) system, the permanent magnet motor comprising: Rotor; a stator having a voltage tap capable of variably connecting the rotor to any one of a low-range voltage path and a high-range voltage path; and a variable frequency drive (VFD) variably connected to the rotor via the low-range voltage path or the high-range voltage path; Wherein, the voltage tap connects the stator to the VFD via the low-range voltage path to implement the HVACR system as a heating system.

2. The permanent magnet motor according to claim 1, wherein: The low range voltage path allows the motor to operate at higher speeds at the same input voltage.

3. The permanent magnet motor according to claim 1, wherein: The low-range voltage path carries the maximum VFD output voltage for the heating system.

4. The permanent magnet motor according to claim 1, wherein: The permanent magnet motor is a multi-tap four-pole motor, wherein further each pole has a corresponding coil branch, and the coil branches for four poles are connected in series.

5. The permanent magnet motor according to claim 1, wherein: The number of poles for the permanent magnet motor is a multiple of four, and further wherein each pole has a corresponding coil branch, and the coil branches for the poles are connected in series.

6. The permanent magnet motor according to claim 1, wherein: The low-range voltage path is delta-connected to the VFD, and the high-range voltage path is wye-connected to the VFD.

7. A permanent magnet motor for a heating, ventilation, air conditioning and refrigeration (HVACR) system, the permanent magnet motor comprising: Rotor; a stator having a voltage tap capable of variably connecting the rotor to any one of a low-range voltage path and a high-range voltage path; and a variable frequency drive (VFD) variably connected to the rotor via the low-range voltage path or the high-range voltage path; Wherein, the voltage tap connects the stator to the VFD via the high-range voltage path to implement the HVAC system as a cooling system.

8. The permanent magnet motor according to claim 7, wherein: The high range voltage path optimizes the motor to operate at higher voltage and lower current at lower speeds.

9. The permanent magnet motor according to claim 7, wherein: The high range voltage path carries the maximum VFD output voltage for the cooling system.

10. A method of controlling an operating mode of a permanent magnet motor according to claim 1 in a heating, ventilation, air conditioning and refrigeration (HVACR) system, the method comprising: The speed of the rotor corresponding to the permanent magnet motor is controlled by switching between connections between the rotor and a variable frequency drive.

11. A method of controlling an operating mode of a permanent magnet motor according to claim 1 in a heating, ventilation, air conditioning and refrigeration (HVACR) system, the method comprising: The speed of a rotor corresponding to the permanent magnet motor is controlled by switching between a wye connection and a delta connection between the stator and a variable frequency drive (VFD).

12. The method according to claim 11, wherein: The Y connection is a high range voltage path.

13. The method according to claim 12, wherein: The Y connection provides power to the HVAC to act as a cooling system.

14. The method according to claim 12, wherein: The high range voltage path optimizes the motor to operate at higher voltage and lower current at lower speeds.

15. The method according to claim 11, wherein: The delta connection is a low range voltage path.

16. The method according to claim 15, wherein: The delta connection provides power to the HVACR to act as a heating system.

17. The method according to claim 15, wherein: The low range voltage path allows the motor to operate at higher speeds at the same input voltage.

18. The method according to claim 11, wherein: The permanent magnet motor is a multi-tap four-pole motor, wherein further each pole has a corresponding coil branch, and the coil branches for four poles are connected in series.

19. The method according to claim 11, wherein: The number of poles for the permanent magnet motor is a multiple of four, and further wherein each pole has a corresponding coil branch, and the coil branches for the poles are connected in series.

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