Motor-driven systems, blowers, compressors, refrigeration equipment

Abstract

This invention provides a technology that can suppress the coil current when irreversibly changing the magnetic flux density of a low-coercivity permanent magnet. [Solution] A motor drive system 1 according to one embodiment of the present disclosure includes a power converter 200 that supplies current to a plurality of coils 32 of a stator 30 in a motor 100, a switching unit 60 that can switch between a delta connection and a Y connection for the connection state between the power converter 200 and the plurality of coils 32, and a control device 300. The control device 300 performs torque control, which rotates the rotor 40 of the motor 100 by switching the connection state to a delta connection using the switching unit 60 and supplying current to the plurality of coils 32 using the power converter 200, and magnetization control, which irreversibly changes the residual magnetic flux density of the permanent magnets 42 of the rotor 40 in the motor 100 by switching the connection state to a Y connection using the switching unit 60 and supplying current to the plurality of coils 32 using the power converter 200.

Description

Technical Field

[0001] The present disclosure relates to a motor drive system and the like.

Background Art

[0002] Conventionally, a technology is known that employs a low coercivity permanent magnet capable of irreversibly changing the magnetic flux density by a magnetic field generated by a current flowing through a coil of an armature, and realizes efficient variable speed operation in a wide range from low speed to high speed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order to irreversibly change the magnetic flux density of a low coercivity permanent magnet, it is necessary to apply a very large current to the coil, which may increase the capacity of the power conversion device that drives the motor.

[0005] An object of the present disclosure is to provide a technology capable of suppressing the current in a coil when irreversibly changing the magnetic flux density of a low coercivity permanent magnet.

Means for Solving the Problems

[0006] In a first aspect of the present disclosure, a motor drive system for driving a motor (100) having a stator (30) including a rotor (40) including a first permanent magnet (42), a stator core (31), and a plurality of coils (32) wound around the stator core (31), the stator (30) being arranged to face the rotor (40) in the radial direction, A current supply unit (200) that supplies current to the plurality of coils (32), A switching unit (60) is provided that can switch between a first connection state and a second connection state regarding the connection state between the current supply unit (200) and the plurality of coils (32). The system comprises a control unit (300) that controls the current supply unit (200) and the switching unit (60), The second wiring state is a wiring state in which, when a predetermined current is passed through the plurality of coils (32), the current supplied from the current supply unit (200) is smaller than that in the first wiring state. The control unit (300) is The first control involves switching the wiring state to the first wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40), The switching unit (60) switches the connection state to the second connection state, and the current supply unit (200) supplies current to the plurality of coils (32) to perform a second control that irreversibly changes the residual magnetic flux density of the first permanent magnet (42). A motor drive system is provided.

[0007] According to this embodiment, the motor drive system can suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of a permanent magnet.

[0008] Furthermore, a second aspect of this disclosure, based on the first aspect described above, The current supply unit (200) supplies a three-phase alternating current to the plurality of coils (32), In the first wiring configuration, the plurality of coils (32) are connected to the current supply unit (200) in a delta connection configuration. In the second wiring configuration, the plurality of coils (32) may be connected to the current supply unit (200) in a Y-connection configuration.

[0009] Furthermore, in a third aspect of this disclosure, based on the first aspect described above, The plurality of coils (32) include a first coil (32U1, 32V1, 32W1) and a second coil (32U2, 32V2, 32W2), In the first wiring configuration, the first coil (32U1, 32V1, 32W1) and the second coil (32U2, 32V2, 32W2) are connected in parallel to the current supply unit (200). In the second wiring configuration, the first coil (32U1, 32V1, 32W1) and the second coil (32U2, 32V2, 32W2) may be connected in series to the current supply unit (200).

[0010] Furthermore, a fourth aspect of this disclosure is based on any one of the first to third aspects described above, In the first wiring configuration described above, the current supply unit (200) and the plurality of coils (32) are connected in a predetermined number of phases of three or more. In the second wiring configuration described above, the current supply unit (200) and the plurality of coils (32) may be connected by only some of the predetermined number of phases.

[0011] Furthermore, the fifth aspect of this disclosure is based on any one of the first to fourth aspects described above, In the first control, the control unit (300) may supply current to three or more predetermined phases using the current supply unit (200), and in the second control, the current supply unit (200) may supply current to only some of the predetermined phases.

[0012] Furthermore, the sixth aspect of this disclosure is based on any one of the first to fifth aspects described above, The control unit (300) may perform a third control by switching the wiring state to the second wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40).

[0013] Furthermore, the seventh aspect of this disclosure is based on any one of the first to fifth aspects described above, The switching unit (60) is capable of switching the connection state between the current supply unit (200) and the plurality of coils (32) between a first connection state, a second connection state, and a third connection state that is different from the first and second connection states. The control unit (300) may perform a fourth control by switching the wiring state to the third wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40).

[0014] Furthermore, the eighth aspect of this disclosure is based on any one of the first to third, sixth, and seventh aspects described above, The rotor (40) has a rotor core (41) containing a soft magnetic material, The first permanent magnet (42) is embedded in the rotor core (41) such that, in a cross section perpendicular to the rotation axis (AX) of the rotor (40), the magnetization direction is along the radial direction at a predetermined circumferential position. In the second control, the control unit (300) may use the switching unit (60) to switch the connection state to the second connection state, and in a cross section perpendicular to the rotation axis (AX), the magnetization direction of the first permanent magnet (42) and the winding axis direction of the first phase coil (32U1) of the stator (30) among the plurality of coils (32) may be substantially coincided, and the current supply unit (200) may be controlled to supply current to the first phase coil (32U1), as well as the second phase coil (32V1) and the third phase coil (32W1) which are adjacent to the first phase coil (32U1) in one and the other circumferential directions.

[0015] Furthermore, the ninth aspect of this disclosure is based on the fourth or fifth aspect described above, The rotor (40) has a rotor core (41) containing a soft magnetic material, The first permanent magnet (42) is embedded in the rotor core (41) such that in a cross-section orthogonal to the rotation axis (AX) of the rotor (40), the magnetization direction inclines with respect to the radial direction at a position in a predetermined circumferential direction. In the second control, the control unit (300) may control the current supply unit (200) to switch the connection state to the second connection state by the switching unit (60), and in a cross-section orthogonal to the rotation axis (AX), the q-axis of the rotor (the virtual line that bisects the angle formed by the winding axes of the first-phase coil (32U1) and the second-phase coil (32V1) adjacent to each other in the circumferential direction among the plurality of coils (32) substantially coincides with the q-axis of the rotor (40), and supply current to the first-phase coil (32U1) and the second-phase coil (32V1).

[0016] Further, in a tenth aspect of the present disclosure, the motor (100) driven by the motor drive system (1) according to any one of the first to ninth aspects described above, and a blower mechanism unit (423A) driven by the motor (100). A blower is provided.

[0017] <00​​​​​​​​​​​​​​​​​​​​

[0020] [Figure 1] This figure shows an example of a motor drive system. [Figure 2] This is a diagram showing the first example of a motor. [Figure 3] This figure shows a second example of a motor. [Figure 4] This figure shows a third example of a motor. [Figure 5] This is a diagram showing the first example of a switching unit. [Figure 6] This is a diagram showing the first example of a switching unit. [Figure 7] This is a diagram showing a second example of the switching mechanism. [Figure 8] This is a diagram showing a second example of the switching mechanism. [Figure 9] This figure illustrates the first example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet. [Figure 10] This figure illustrates the first example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet. [Figure 11] This figure illustrates a second example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet. [Figure 12] This figure illustrates a second example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet. [Figure 13] This is a diagram showing an example of an air conditioner. [Modes for carrying out the invention]

[0021] The embodiments will be described below with reference to the drawings.

[0022] [Motor drive system] The motor drive system 1 according to this embodiment will be described with reference to Figure 1.

[0023] Figure 1 shows an example of a motor drive system 1.

[0024] As shown in Figure 1, the motor drive system 1 includes a motor 100, a power converter 200, and a control device 300. The motor drive system 1 operates the power converter 200 under the control of the control device 300 to drive the motor 100.

[0025] The motor (also called a "rotating electric machine" or "rotary electric motor") 100 is a rotating electric machine that is electrically connected to a power converter 200 via a power line 150 and is rotationally driven by alternating current supplied from the power converter 200. The motor 100 is driven by alternating current of three or more predetermined phases supplied from the power converter 200, such as a three-phase alternating current of U-phase, V-phase, and W-phase.

[0026] The motor 100 includes a switching unit 60.

[0027] The switching unit 60 switches the wiring state between the multiple coils 32 of the motor 100 (see Figures 2 to 4) and the power converter 200. Details will be described later (see Figures 5 to 8).

[0028] Furthermore, the switching unit 60 may be provided outside the motor 100.

[0029] The power converter 200 operates under the control of the control device 300 and drives the motor 100 by converting the power supplied from the power supply PS into AC of a predetermined frequency and voltage and outputting it to the motor 100.

[0030] For example, the power converter 200 includes a rectifier that converts alternating current supplied from a power source PS into direct current, a smoothing circuit that smooths the direct current output from the rectifier, and an inverter circuit that converts the direct current smoothed by the smoothing circuit into alternating current of a predetermined frequency and voltage. Alternatively, the power converter 200 may convert the direct current supplied from the power source PS into alternating current using the inverter circuit. Furthermore, the power converter 200 may include a matrix converter that directly converts the alternating current supplied from the power source PS into alternating current of a predetermined frequency and voltage.

[0031] The control device 300 controls the drive of the motor 100 by controlling the power converter 200. For example, the control device 300 can control the operation of the power converter 200 by generating and outputting gate signals that drive the switching elements included in the inverter circuit and matrix converter of the power converter 200.

[0032] Furthermore, the control device 300 switches the connection state between the power converter 200 and the multiple coils 32 in the motor 100 by controlling the switching unit 60.

[0033] The functions of the control device 300 can be realized by any hardware, or any combination of hardware and software. For example, the control device 300 is mainly composed of a computer including a CPU (Central Processing Unit), memory device, auxiliary storage device, input / output interface device, etc.

[0034] [First example of a motor] Referring to Figure 2, a first example of a motor 100 to be driven by the motor drive system 1 according to this embodiment will be described.

[0035] Figure 2 is a cross-sectional view showing a first example of the motor 100. Specifically, Figure 2 is a cross-sectional view of a first example of the motor 100, taken from a plane perpendicular to the rotation axis AX.

[0036] Hereinafter, the axial, radial, and circumferential directions, with respect to the axis of rotation, may simply be referred to as "axial direction," "radial direction," and "circumferential direction," respectively.

[0037] As shown in Figure 2, the motor 100 is a so-called radial gap type and includes a stator 30 and a rotor 40 that face each other radially with an air gap between them.

[0038] The stator (also called the "fixator") 30 is the armature, positioned radially outward from the rotor 40, and fixed to a housing (not shown). The stator 30 includes a stator core 31 and a plurality of coils 32.

[0039] The stator core (also called the "stator iron core") 31 is formed of a soft magnetic material and functions as a magnetic path for the magnetic flux caused by the current flowing through the coil 32 and the magnetic flux of the permanent magnets 42 of the rotor 40. Examples of soft magnetic materials applied to the stator core 31 include electromagnetic steel sheets and powdered magnetic cores. The soft magnetic material may also be an amorphous soft magnetic material composed of an amorphous alloy or a nanocrystalline soft magnetic material composed of a nanocrystalline alloy. The stator core 31 includes a back yoke portion 31A having a substantially cylindrical shape centered on the rotation axis AX, and a plurality (six in this example) of teeth portions 31B protruding radially inward from the inner circumferential surface of the back yoke portion 31A. The "subjective" in relation to arrangement and shape, for example, is intended to allow for manufacturing errors (tolerances), and is used in the same sense hereafter. ru.

[0040] Multiple teeth portions 31B are arranged on the inner circumference side of the back yoke portion 31A at approximately equal intervals in the circumferential direction.

[0041] Multiple coils (also called "windings") 32 are wound around each of the multiple tooth sections 31B by concentrated winding. An insulating material, such as an insulating film made of PET (Polyethylene Terephthalate), is interposed between the coils 32 and the tooth sections 31B.

[0042] For example, the motor 100 is driven by a three-phase AC current consisting of U-phase, V-phase, and W-phase, and the six coils 32 each include two coils for the U-phase, V-phase, and W-phase.

[0043] Furthermore, the coil 32 may be wound in a distributed winding manner so as to span two or more tooth sections 31B.

[0044] The rotor (also called the "rotor") 40 is positioned radially inward of the stator 30 and is mounted on the rotating shaft 50, and is capable of rotating around the rotation axis AX of the rotating shaft 50. The rotor 40 includes a rotor core 41 and a plurality of permanent magnets 42.

[0045] The rotor core (also called the "rotor iron core") 41 is formed from a soft magnetic material and functions as a magnetic path for the magnetic field caused by the current flowing through the coil 32 of the stator 30 and the magnetic field of the permanent magnet 42. Examples of soft magnetic materials applied to the rotor core 41 include electromagnetic steel sheets and powdered magnetic cores. The soft magnetic material may also be an amorphous soft magnetic material composed of amorphous alloys or a nanocrystalline soft magnetic material composed of nanocrystalline alloys.

[0046] The rotor core 41 has a cylindrical shape centered on the rotation axis AX, and is provided with a through-hole that penetrates axially, also centered on the rotation axis AX. The rotation shaft 50 is inserted through and fixed in the through-hole. As a result, the rotor 40 can rotate together with the rotation shaft 50.

[0047] The permanent magnet 42 is a permanent magnet with relatively low coercivity, and its residual magnetic flux density can be irreversibly changed by the magnetic flux of the current flowing through the coil 32 of the stator 30. Specifically, the permanent magnet 42 can be magnetized by applying a magnetic flux in the same direction as the magnetization direction through the action of the current flowing through the coil 32, and can be demagnetized by applying a magnetic flux in the opposite direction to the magnetization direction through the action of the current flowing through the coil 32. The permanent magnet 42 is, for example, an Alnico magnet.

[0048] Furthermore, in addition to the permanent magnet 42, the motor 100 may be provided with a permanent magnet having a relatively high coercivity such that the residual magnetic flux density does not irreversibly change due to the magnetic flux of the current in the coil 32. For example, the permanent magnet with relatively high coercivity is positioned radially inward from the permanent magnet 42 at the same circumferential position as the permanent magnet 42, so as to be magnetically coupled in series with the permanent magnet 42. In this case, the permanent magnet with relatively high coercivity is, for example, a neodymium magnet.

[0049] Multiple permanent magnets 42 are arranged at equal intervals in the circumferential direction on the rotor core 41. In this example, the multiple permanent magnets 42 are embedded inside the rotor core 41. That is, in this example, the motor 100 is a so-called interior permanent magnet (IPM) motor. Specifically, holes (also called "magnet slots") are formed in the rotor core 41 along the axial direction, and the permanent magnets 42 are embedded inside the rotor core 41 by being inserted into these holes.

[0050] In this example, the permanent magnet 42 has an elongated rectangular shape (specifically, one side is sufficiently longer than the other) when viewed in the direction along the rotation axis AX. The permanent magnet 42 is positioned such that, when viewed in the direction along the rotation axis AX, its longer side is approximately perpendicular to the radial direction (i.e., its shorter side is aligned with the radial direction) at a predetermined circumferential position. The permanent magnet 42 is magnetized in the direction of its shorter side (i.e., the radial direction), and is positioned such that the polarity of its magnetic poles (N pole or S pole) at both ends in the direction of its shorter side is different from that of other permanent magnets 42 adjacent to it in the circumferential direction.

[0051] In this example, spaces that function as flux barriers may be formed at both ends of the permanent magnet 42 in the long-side direction in the rotor core 41.

[0052] In this example, the motor 100 has a 4-pole, 6-slot configuration consisting of a combination of 6 coils 32 and 4 permanent magnets 42.

[0053] In this example, the motor 100 may have a configuration different from that of a 4-pole, 6-slot motor. Specifically, the number of coil slots, i.e., the number of coils 32, may be 5 or less, or 7 or more. Also, the number of poles, i.e., the number of permanent magnets 42, may be 3 or less, or 5 or more.

[0054] [Second example of a motor] Referring to Figure 3, a second example of the motor 100 according to this embodiment will be described.

[0055] In this example, the same or corresponding components of the motor 100 as in the first example described above are denoted by the same reference numerals. The explanation will focus on the parts that differ from the first example, and the explanation of parts that are the same or corresponding to the first example may be omitted. The same correspondence will be taken with respect to the third example described later in relation to the first and second examples of motor 100.

[0056] Figure 3 is a cross-sectional view showing a second example of the motor 100. Specifically, Figure 3 is a cross-sectional view of the second example of the motor 100, taken from a plane perpendicular to the rotation axis AX.

[0057] The motor 100 in this example differs from the first example described above in the configuration of the permanent magnet 42.

[0058] The multiple permanent magnets 42 are arranged at approximately equal intervals in the circumferential direction, similar to the first example described above. The permanent magnets 42 are also relatively low coercivity permanent magnets, similar to the first example described above, and their residual magnetic flux density can be irreversibly changed by the magnetic flux of the current flowing through the coil 32 of the stator 30. The permanent magnets 42 include two magnetic members 42A and 42B.

[0059] Both magnetic members 42A and 42B have an elongated rectangular shape (specifically, one side is sufficiently longer than the other) when viewed along the axial direction. When viewed along the axial direction, the magnetic members 42A and 42B are arranged approximately symmetrically with respect to the axis corresponding to the radial direction, such that at a predetermined circumferential position, their longer sides form a V-shape that is convex radially inward.

[0060] Both magnetic members 42A and 42B are magnetized in the short-side direction such that the magnetic poles at both ends in the short-side direction are the same. Therefore, the magnetization direction of magnetic members 42A and 42B is inclined with respect to the radial direction of the circumferential position where the permanent magnet 42 is located.

[0061] In this example, spaces that function as flux barriers may be formed at both ends of the magnetic members 42A and 42B in the long-side direction in the rotor core 41.

[0062] Furthermore, in this example, the permanent magnet 42 may include three or more magnetic members. In this case, the three or more magnetic members may be arranged to form a U-shape by the longer sides of the magnetic members, rather than a V-shape. Also, in this example, a V-shaped or U-shaped permanent magnet 42 may be formed by a single magnetic member.

[0063] Furthermore, in this example, the coercivity of only one of the magnet members 42A and 42B may be low enough that the residual magnetic flux density can be irreversibly changed by the magnetic flux of the current in the coil 32, while the coercivity of the other magnet member may be relatively high enough that the residual magnetic flux density cannot be irreversibly changed by the magnetic flux of the current in the coil 32. For example, magnet member 42B may have a relatively low coercivity, while magnet member 42A may have a relatively high coercivity. Also, in the motor 100, similar to the first example described above, in addition to the permanent magnet 42, a permanent magnet having a relatively high coercivity such that the residual magnetic flux density cannot be irreversibly changed by the magnetic flux of the current in the coil 32 may be provided. In this case, the permanent magnet having a relatively high coercivity may be composed of a single magnet member, or, like the permanent magnet 42, may be composed of multiple magnet members.

[0064] [Third example of a motor] Referring to Figure 4, a third example of the motor 100 according to this embodiment will be described.

[0065] Figure 4 is a cross-sectional view showing a third example of the motor 100. Specifically, Figure 4 is a cross-sectional view of the third example of the motor 100 taken from a plane perpendicular to the rotation axis AX.

[0066] The motor 100 in this example differs from the first and second examples described above in the configuration of the permanent magnet 42.

[0067] The multiple permanent magnets 42 are arranged at equal intervals in the circumferential direction, similar to the first and second examples described above. The permanent magnets 42 are permanent magnets with relatively low coercivity, similar to the first and second examples described above, and their residual magnetic flux density can be irreversibly changed by the magnetic flux of the current flowing through the coil 32 of the stator 30.

[0068] The permanent magnet 42 has an elongated rectangular shape (specifically, one side is sufficiently longer than the other) when viewed along the axial direction. When viewed along the axial direction, the permanent magnet 42 is positioned at a predetermined circumferential position such that its longer side aligns with the radial direction.

[0069] The permanent magnets 42 are magnetized in the short-side direction, and are arranged such that the polarity of the magnetic poles (N pole or S pole) at both ends in the short-side direction is different from that of other permanent magnets 42 adjacent to them in the circumferential direction. Therefore, the magnetization direction of the permanent magnets 42 is tilted 90 degrees with respect to the radial direction of the circumferential position where the permanent magnets 42 are arranged.

[0070] In this example, unlike the first and second examples described above, the magnetic poles of the rotor 40 are located not at the circumferential positions where the permanent magnets 42 are arranged, but at the circumferential positions in the center between adjacent permanent magnets 42.

[0071] Furthermore, in the rotor core 41, spaces that function as flux barriers may be formed at both ends of the magnetic members 42A and 42B in the long-side direction.

[0072] [First example of a switching mechanism] Referring to Figures 5 and 6, a first example of the switching unit 60 will be described.

[0073] Figures 5 and 6 show a first example of the switching unit 60. Specifically, Figure 5 shows the state in which the switching unit 60 switches the connection state between the power converter 200 and the multiple coils 32 to a connection state that irreversibly changes the residual magnetic flux density of the permanent magnet 42 (hereinafter referred to as the "second connection state"). Figure 6 shows the state in which the switching unit 60 switches the connection state between the power converter 200 and the multiple coils 32 to a connection state that rotates the rotor 40 of the motor 100 (hereinafter referred to as the "first connection state").

[0074] Figure 5 includes Figure 5A, which shows the state of the switching unit 60 for achieving the second wiring state, and Figure 5B, which schematically shows the connection state between the power converter 200 and the multiple coils 32 achieved by the state of the switching unit 60 in Figure 5A. Similarly, Figure 6 includes Figure 6A, which shows the state of the switching unit 60 for achieving the first wiring state, and Figure 6B, which schematically shows the connection state between the power converter 200 and the multiple coils 32 achieved by the state of the switching unit 60 in Figure 6A.

[0075] In this example, as with the first to third examples of the motor 100 described above, the explanation will proceed on the premise that the stator 30 includes six coils 32. In this example, the six coils will be distinguished and explained as U-phase coils 32U1, 32U2, V-phase coils 32V1, 32V2, and W-phase coils 32W1, 32W2. The same applies to the explanation of the second example of the switching unit 60 described later.

[0076] As shown in Figures 5 and 6, the switching unit 60 includes switches 61U, 61V, and 61W, and switches 62UV, 62VW, and 62WU. These switches are semiconductor switches such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors).

[0077] The power line 150 connecting the power converter 200 and the multiple coils 32 includes a U-phase line 150U, a V-phase line 150V, and a W-phase line 150W.

[0078] Coils 32U1 and 32U2 are electrically connected in series.

[0079] Coil 32U1 has one end electrically connected to the U-phase wire 150U and the other end electrically connected to one end of coil 32U2. Coil 32U2 has one end electrically connected to the other end of coil 32U1 and the other end electrically connected in parallel to one end of switch 61U and one end of switch 62UV.

[0080] Coils 32V1 and 32V2 are electrically connected in series.

[0081] Coil 32V1 has one end electrically connected to the V-phase line 150V and the other end electrically connected to one end of coil 32V2. Coil 32V2 has one end electrically connected to the other end of coil 32V1 and the other end electrically connected in parallel to one end of switch 61V and one end of switch 62VW.

[0082] Coils 32W1 and 32W2 are electrically connected in series.

[0083] Coil 32W1 has one end electrically connected to the W phase wire 150W and the other end electrically connected to one end of coil 32W2. Coil 32W2 has one end electrically connected to the other end of coil 32W1 and the other end electrically connected in parallel to one end of switch 61W and one end of switch 62WU.

[0084] Switch 61U has one end electrically connected to the other end of coil 32U2 and the other end electrically connected to the neutral point NP. Switch 61V has one end electrically connected to the other end of coil 32V2 and the other end electrically connected to the neutral point NP. Switch 61W has one end electrically connected to the other end of coil 32W2 and the other end electrically connected to the neutral point NP.

[0085] Switch 62UV has one end electrically connected to the other end of coil 32U2, and the other end electrically connected to the V-phase wire 150V. Switch 62VW has one end electrically connected to the other end of coil 32V2, and the other end electrically connected to the W-phase wire 150W. Switch 62WU has one end electrically connected to the other end of coil 32W2, and the other end electrically connected to the U-phase wire 150U.

[0086] The control device 300 can select from a predetermined number of control modes. These control modes include a magnetization mode and a torque mode. The magnetization mode is a control mode for irreversibly changing the residual magnetic flux density of the permanent magnet 42 by the current of the multiple coils 32 (magnetization control). The torque mode is a control mode for generating torque in the rotor 40 by the current of the multiple coils 32 and rotating the motor 100 (torque control).

[0087] As shown in Figure 5A, in magnetization mode, the switching unit 60 has switches 61U, 61V, and 61W turned ON (i.e., closed), while switches 62UV, 62VW, and 62WU are turned OFF (i.e., opened). Specifically, in magnetization mode, the control device 300 controls the switching unit 60 to switch switches 61U, 61V, and 61W to ON and switches 62UV, 62VW, and 62WU to OFF, and then performs magnetization control. As a result, as shown in Figure 5B, the control device 300 can perform magnetization control based on a second connection state in which the power converter 200 and the multiple coils 32 are connected in a Y connection.

[0088] On the other hand, as shown in Figure 6A, in torque mode, the switching unit 60 is switched OFF (i.e., open) with switches 61U, 61V, and 61W turned OFF, while switches 62UV, 62VW, and 62WU are turned ON (i.e., closed). Specifically, in torque mode, the control device 300 controls the switching unit 60 to switch switches 61U, 61V, and 61W to OFF and switches 62UV, 62VW, and 62WU to ON, and then performs torque control. As a result, as shown in Figure 6B, the control device 300 can perform torque control based on a first connection state in which the power converter 200 and the multiple coils 32 are connected in a delta connection.

[0089] For example, in magnetization control, it is necessary to apply a very large current to the coil 32 in order to increase or decrease the magnetization of the permanent magnet 42.

[0090] In contrast, in this example, when magnetization control is performed, the control device 300 switches the switching unit 60 so that the power converter 200 and the multiple coils 32 are connected in a Y-connection beforehand. Therefore, the control device 300 can reduce the current that needs to be supplied from the power converter 200 to apply the same current to the coils 32 compared to when the multiple coils 32 are connected in a delta connection. Thus, the control device 300 can suppress the current supplied from the power converter 200 to the multiple coils 32 in magnetization control, assuming torque control when the multiple coils 32 are connected in a delta connection.

[0091] In this example, there are two coils 32 for each phase, but there may be three or more coils 32 for each phase. In this case as well, the same function and effect can be achieved by configuring the switching unit 60 so that multiple coils 32, each consisting of three or more coils 32 for each phase, can be selectively connected in either a Y connection or a delta connection.

[0092] Furthermore, in this example, the control device 300 may control the switching unit 60 in torque control mode to select a second wiring state in addition to the first wiring state. In this case, the control device 300 may selectively switch between the first wiring state and the second wiring state to perform torque control. The same applies to the second example described below.

[0093] [Second example of a switching mechanism] Referring to Figures 7 and 8, a second example of the switching unit 60 will be described.

[0094] In the following example, we will focus on explaining the parts that differ from the first example of the switching unit 60 described above, and may omit explanations of parts that are the same as or corresponding to the first example.

[0095] Figures 7 and 8 show a second example of the switching unit 60. Specifically, Figure 7 shows the state in which the switching unit 60 switches the connection state between the power converter 200 and the multiple coils 32 to a second connection state for irreversibly changing the residual magnetic flux density of the permanent magnet 42. Figure 8 shows the state in which the switching unit 60 switches the connection state between the power converter 200 and the multiple coils 32 to a first connection state for rotating the rotor 40 of the motor 100.

[0096] Figure 7 includes Figure 7A, which shows the state of the switching unit 60 for achieving the second wiring state, and Figure 7B, which schematically shows the connection state between the power converter 200 and the multiple coils 32 achieved by the state of the switching unit 60 in Figure 7A. Similarly, Figure 8 includes Figure 8A, which shows the state of the switching unit 60 for achieving the first wiring state, and Figure 8B, which schematically shows the connection state between the power converter 200 and the multiple coils 32 achieved by the state of the switching unit 60 in Figure 8A.

[0097] As shown in Figures 7 and 8, the switching unit 60 includes switches 63U, 63V, and 63W, and switches 64U1, 64U2, 64V1, 64V2, 64W1, and 64W2. These switches are semiconductor switches such as MOSFETs and IGBTs.

[0098] Switch 64U1 has one end electrically connected to the U-phase wire 150U and the other end electrically connected to one end of coil 32U2. Switch 64V1 has one end electrically connected to the V-phase wire 150V and the other end electrically connected to one end of coil 32V2. Switch 64W1 has one end electrically connected to the W-phase wire 150W and the other end electrically connected to one end of coil 32W2.

[0099] Coil 32U1 has one end electrically connected to the U-phase wire 150U, and the other end electrically connected in parallel to one end of switch 63U and one end of switch 64U2. Coil 32U2 has one end electrically connected in parallel to the other end of switch 63U and the other end of switch 64U1, and the other end electrically connected to the neutral point NP.

[0100] Coil 32V1 has one end electrically connected to the V-phase line 150V, and the other end electrically connected in parallel to one end of switch 63V and one end of switch 64V2. Coil 32V2 has one end electrically connected in parallel to the other end of switch 63V and the other end of switch 63V1, and the other end electrically connected to the neutral point NP.

[0101] Coil 32W1 has one end electrically connected to the W phase wire 150W, and the other end electrically connected in parallel to one end of switch 63W and one end of switch 64W2. Coil 32W2 has one end electrically connected in parallel to the other end of switch 63W and the other end of switch 63W1, and the other end electrically connected to the neutral point NP.

[0102] As shown in Figure 7A, in magnetization mode, the switching unit 60 has switches 63U, 63V, and 63W turned ON (i.e., closed), while switches 64U1, 64U2, 64V1, 64V2, 64W1, and 64W2 are turned OFF (i.e., opened). Specifically, in magnetization mode, the control device 300 controls the switching unit 60 to switch switches 63U, 63V, and 63W to ON and switches 64U1, 64U2, 64V1, 64V2, 64W1, and 64W2 to OFF, and then performs magnetization control. As a result, as shown in Figure 7B, the control device 300 can perform magnetization control based on a second connection state in which the power converter 200 and the multiple coils 32 are connected in a Y connection and two coils 32 for each phase are connected in series.

[0103] On the other hand, as shown in Figure 8A, in torque mode, the switching unit 60 is switched OFF (i.e., opened) when switches 63U, 63V, and 63W are turned OFF, while switches 64U1, 64U2, 64V1, 64V2, 64W1, and 64W2 are turned ON (i.e., closed). Specifically, in torque mode, the control device 300 controls the switching unit 60 to switch switches 63U, 63V, and 63W to OFF, and switches 64U1, 64U2, 64V1, 64V2, 64W1, and 64W2 to ON, and then performs torque control. As a result, as shown in Figure 8B, the control device 300 can perform torque control based on a first connection state in which the power converter 200 and the multiple coils 32 are connected in a Y connection, with two coils 32 for each phase connected in parallel.

[0104] Thus, in this example, when the control device 300 performs magnetization control, it switches the switching unit 60 in advance so that the power converter 200 and the multiple coils 32 are connected in parallel with the two coils of each phase connected beforehand. Therefore, the control device 300 can reduce the current that needs to be supplied from the power converter 200 to apply the same current to the coils 32 compared to when the two coils 32 of each phase are connected in parallel. Thus, the control device 300 can suppress the current supplied from the power converter 200 to the multiple coils 32 in magnetization control, assuming torque control with the coils 32 of each phase electrically connected in parallel.

[0105] In this example, there are two coils 32 for each phase, but there may be three or more coils 32 for each phase. In this case as well, the same function and effect can be achieved by configuring the switching unit 60 to allow selective connection of the three or more coils 32 for each phase in either series or parallel.

[0106] Furthermore, although the motor 100 is driven by a three-phase AC power supply in this example, as described above, the motor 100 may also be driven by an AC power supply with four or more predetermined phases. In this case as well, the same function and effect can be achieved by configuring the switching unit 60 to allow selective connection of the multiple coils of each phase in either series or parallel.

[0107] Furthermore, in this example, we illustrate a case where the switching unit 60 switches between series and parallel connections of the coils of each phase, assuming that the multiple coils 32 are connected in a Y-connection. However, it is also possible to assume that they are connected in a delta connection, or in any other way. In other words, in this example, the connection type of the multiple coils 32 is arbitrary, and the same applies when the motor 100 is driven by an AC current with four or more predetermined phases.

[0108] [First example of a method for changing the residual magnetic flux density of a permanent magnet] Referring to Figures 9 and 10, a first example of a method for irreversibly changing the residual magnetic flux density of the permanent magnet 42 will be described.

[0109] In the following example, we will proceed with the explanation assuming the motor 100 is in the form of the first example (Figure 2) described above.

[0110] Figures 9 and 10 illustrate a first example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet 42. Specifically, Figure 9 shows the rotational position of the rotor 40 when the residual magnetic flux density of the permanent magnet 42 is irreversibly changed. Figure 10 is a time chart showing the currents flowing through multiple coils 32 (specifically, coils 32U1, 32V1, and 32W1) in magnetization mode, assuming the rotational position of the rotor 40 in Figure 9.

[0111] Note that, unlike Figure 2 above, Figure 9 depicts a motor 100 with 6 poles and 9 slots.

[0112] As shown in Figure 9, in this example, the control device 300, in magnetization mode, applies pulsed current to the U-phase coil 32U1 and the adjacent V-phase coil 32V1 and W-phase coil 32W1 on either side of the coil 32U1, with the d-axis Ad of the rotor 40 (of which the d-axis Ad and q-axis Aq) approximately coinciding with the winding axis Au of the U-phase coil 32U1. In this example, the d-axis of the rotor 40 corresponds to the magnetization direction of the permanent magnet 42. The "abbreviated" in relation to control is intended to allow for errors that may occur depending on the control method, and will be used in the same sense hereafter.

[0113] The control device 300 may increase or decrease the magnetization of the permanent magnet 42 by magnetization mode while the motor 100 is rotating, or it may increase or decrease the magnetization of the permanent magnet 42 by magnetization mode while the motor 100 is stopped at the above-mentioned rotation position. The same applies to the second example described below.

[0114] For example, as shown in Figure 10, the control device 300 supplies the maximum current Ia that can be supplied from the power converter 200 to the U-phase coil 32U1, and supplies the V-phase coil 32V1 and the W-phase coil 32W1 with a current that is half the magnitude of the maximum current Ia (=Ia / 2) and of the opposite polarity.

[0115] As a result, the magnetic flux generated between the U-phase coil 32U1, the V-phase coil 32V1, and the W-phase coil 32W1 in the stator 30 acts on the permanent magnet 42 in the magnetization direction, i.e., radially. Therefore, the control device 300 can increase or decrease the magnetization of the permanent magnet 42.

[0116] In this example, the control device 300 may, in magnetization mode, supply pulsed current to the V-phase coil 32V1 and the adjacent U-phase and W-phase coils 32 on both sides of coil 32V1, while the d-axis Ad of the rotor 40 coincides with the winding axis of the V-phase coil 32V1. Similarly, the control device 300 may, in magnetization mode, supply pulsed current to the W-phase coil 32W1 and the adjacent U-phase and V-phase coils 32 on both sides of coil 32W1, while the d-axis Ad of the rotor 40 coincides with the winding axis of the W-phase coil 32W1.

[0117] [Second example of a method for changing the residual magnetic flux density of a permanent magnet] As shown in Figures 11 and 12, a second example of a method for irreversibly changing the residual magnetic flux density of the permanent magnet 42 is described.

[0118] In the following example, we will proceed with the explanation assuming the motor 100 is in the form of the second example (Figure 3) described above.

[0119] Figures 11 and 12 illustrate a second example of a method for irreversibly changing the residual magnetic flux density of a permanent magnet 42. Specifically, Figure 11 shows the rotational position of the rotor 40 when the residual magnetic flux density of the permanent magnet 42 is irreversibly changed. Figure 12 is a time chart showing the currents flowing through multiple coils 32 (specifically, coils 32U1 and 32V1) in magnetization mode, assuming the rotational position of the rotor 40 in Figure 11.

[0120] Note that, unlike Figure 3 above, Figure 11 depicts a motor 100 with 6 poles and 9 slots.

[0121] As shown in Figure 11, in this example, the control device 300 supplies pulsed current to the U-phase coil 32V1 and the V-phase coil 32V1 when the q-axis Aq of the rotor 40 (one of the d-axis Ad and q-axis Aq) and the virtual bisector Auv of the winding axis Au of the U-phase coil 32U1 and the winding axis Av of the V-phase coil 32V1 are approximately coincident.

[0122] For example, as shown in Figure 12, the control device 300 supplies the maximum current Ia that can be supplied from the power converter 200 to the U-phase coil 32U1, and supplies the V-phase coil 32V1 with a current of the same magnitude but opposite polarity.

[0123] As a result, the magnetic flux generated between the U-phase coil 32U1 and the V-phase coil 32V1 acts in the magnetization direction of the magnetic members 42A and 42B, which are arranged to be inclined with respect to the radial direction (i.e., the d-axis) of the circumferential position where the permanent magnet 42 is located. Therefore, the control device 300 can increase or decrease the magnetization of the permanent magnet 42.

[0124] In this example, the control device 300 may, in magnetization mode, supply pulsed current to the U-phase and W-phase coils 32 when the q-axis Aq of the rotor 40 and the virtual bisectors of the winding axes of the U-phase and W-phase coils 32 are approximately coincident. Similarly, the control device 300 may, in magnetization mode, supply pulsed current to the V-phase and W-phase coils 32 when the q-axis Aq of the rotor 40 and the virtual bisectors of the winding axes of the V-phase and W-phase coils 32 are approximately coincident.

[0125] Furthermore, the method in this example can be used as a method to irreversibly change the residual magnetic flux density of the permanent magnet 42 in the motor 100 of the third example (Figure 4) described above.

[0126] Furthermore, in this example, since current is supplied to only two of the U-phase, V-phase, and W-phase coils 32, the control device 300 may control the switching unit 60 so that, in magnetization mode, only two of the U-phase, V-phase, and W-phase coils 32 are electrically connected to the power converter 200.

[0127] For example, in Figure 5 above, only the two-phase switches in the switching unit 60 that supply current to coil 32 (out of switches 61U, 61V, and 61W) are turned ON, while the remaining one-phase switch is turned OFF. Also, for example, in Figure 7 above, only the two-phase switches in the switching unit 60 that supply current to coil 32 (out of switches 63U, 63V, and 63W) are turned ON, while the remaining one-phase switch is turned OFF.

[0128] [Examples of applications for motor drive systems] Refer to Figure 13 to explain an example of the application of the motor drive system 1.

[0129] Figure 13 shows an example of an air conditioner 400.

[0130] As shown in Figure 13, the air conditioner 400 includes an outdoor unit 410, an indoor unit 420, and refrigerant pathways 430 and 440. The air conditioner 400 operates a refrigeration cycle consisting of the outdoor unit 410, indoor unit 420, refrigerant pathways 430 and 440, etc., to adjust the temperature, humidity, etc. of the room in which the indoor unit 420 is installed.

[0131] The outdoor unit 410 is located outside the building whose temperature and other properties are to be controlled. The outdoor unit 410 is connected to one end of each of the refrigerant paths 430 and 440, drawing refrigerant from one of the refrigerant paths 430 and 440 and discharging refrigerant to the other.

[0132] The indoor unit 420 is placed inside the building to be controlled, including temperature adjustment. The indoor unit 420 is connected to the other end of the refrigerant paths 430 and 440, drawing refrigerant from one of the refrigerant paths 430 and 440 and discharging refrigerant to the other.

[0133] The refrigerant paths 430 and 440 are, for example, composed of pipes and connect the outdoor unit 410 and the indoor unit 420 so that the refrigerant can circulate between the outdoor unit 410 and the indoor unit 420.

[0134] The outdoor unit 410 includes refrigerant paths L1 to L6, oil paths L7 and L8, a four-way switching valve 411, an accumulator 412, a compressor 413, an oil separator 414, an outdoor heat exchanger 415, an outdoor expansion valve 416, and a fan 417.

[0135] Refrigerant pathways L1 to L6 are configured, for example, as pipes.

[0136] The refrigerant path L1 connects one end of the refrigerant path 430 outside the outdoor unit 410 to the four-way switching valve 411.

[0137] The refrigerant path L2 connects the four-way switching valve 411 to the inlet of the compressor 413. The refrigerant path L2 includes refrigerant paths L21 and L22.

[0138] Refrigerant path L21 connects the four-way switching valve 411 and the accumulator 412. Refrigerant path L22 connects the accumulator 412 and the inlet of the compressor 413.

[0139] The refrigerant path L3 connects the four-way switching valve 411 to the outlet of the compressor 413. The refrigerant path L3 includes refrigerant paths L31 and L32.

[0140] Refrigerant path L31 connects the outlet of compressor 413 to oil separator 414. Refrigerant path L32 connects the four-way switching valve 411 to oil separator 414.

[0141] The refrigerant path L4 connects the four-way switching valve 411 and the outdoor heat exchanger 415.

[0142] The refrigerant path L5 connects the outdoor heat exchanger 415 and the outdoor expansion valve 416.

[0143] The refrigerant path L6 connects one end of the refrigerant path 440 outside the outdoor unit 410 to the outdoor expansion valve 416.

[0144] The oil path L7 is configured, for example, as a pipeline and is used to allow the oil separated by the oil separator 414 to flow into the refrigerant path L22 and return it to the compressor 413 through the refrigerant path L22.

[0145] Furthermore, the oil passing through oil path L7 may contain, for example, a liquid-phase refrigerant (hereinafter referred to as "liquid refrigerant"). In other words, not only oil but also liquid refrigerant flows through oil path L7.

[0146] The oil path L8 is configured, for example, as a pipeline and is used to allow oil containing liquid refrigerant separated by the accumulator 412 to flow into the refrigerant path L22 and return it to the compressor 413 through the refrigerant path L22.

[0147] The four-way switching valve 411 reverses the flow of refrigerant circulation between the cooling operation and the heating operation of the air conditioner 400.

[0148] During cooling operation of the air conditioner 400, the four-way diverter valve 411 connects the paths shown by the solid lines in Figure 1. Specifically, during cooling operation of the air conditioner 400, the four-way diverter valve 411 connects the refrigerant path L1 and refrigerant path L2, and the refrigerant path L3 and refrigerant path L4.

[0149] On the other hand, when the air conditioner 400 is in heating operation, the four-way diverter valve 411 connects the dotted lines in Figure 1. Specifically, when the air conditioner 400 is in heating operation, the four-way diverter valve 411 connects the refrigerant path L4 and refrigerant path L2, and the refrigerant path L1 and refrigerant path L3.

[0150] The accumulator 412 separates the liquid refrigerant contained in the refrigerant drawn in from the refrigerant path L21 and discharges the refrigerant, from which some or all of the liquid refrigerant has been removed, into the refrigerant path L22. The liquid refrigerant separated by the accumulator 412 contains oil. The accumulator 412 is provided with an oil outlet connected to the oil path L8, and the oil containing the separated refrigerant flows out into the oil path L8 through the oil outlet and is returned to the compressor 413 through the oil path L8 and the refrigerant path L22.

[0151] The compressor 413 draws in refrigerant from the refrigerant path L22, compresses it to high pressure, and discharges it into the refrigerant path L31. The compressor 413 includes a compression mechanism 413A that compresses the refrigerant and a motor 100 that drives the compression mechanism 413A. Thus, the motor drive system 1 can drive the compressor 413 by driving the motor 100. The compressor 413 is, for example, a positive displacement compressor. A positive displacement compressor may be reciprocating or rotary. Examples of rotary compressors include rotary compressors, scroll compressors, screw compressors, etc. The compressor 413 may also be a centrifugal compressor (also called a "turbo compressor").

[0152] Furthermore, the components of the motor drive system 1 other than the motor 100, namely the power converter 200 and the control device 300, may all be mounted on the compressor 413, or some or all of them may be provided outside the compressor 413. In the latter case, the power converter 200 and the control device 300 may be mounted on the air conditioner 400, or they may be provided outside the air conditioner 400.

[0153] During cooling operation of the air conditioner 400, the high-temperature, high-pressure refrigerant compressed by the compressor 413 flows into the outdoor heat exchanger 415 through refrigerant paths L3 and L4.

[0154] On the other hand, during heating operation of the air conditioner 400, the high-temperature, high-pressure refrigerant compressed by the compressor 413 flows out through refrigerant paths L3 and L1 to the refrigerant path 430 outside the outdoor unit 410. Then, the high-temperature, high-pressure refrigerant flows into the indoor unit 420 through the refrigerant path 430.

[0155] The oil separator 414 separates oil from the refrigerant flowing in from the refrigerant path L31, and after some or all of the oil has been separated and removed, the remaining refrigerant flows out into the refrigerant path L32. The oil separator 414 is also provided with an oil outlet connected to the oil path L7, and the oil separated from the refrigerant flows out into the oil path L7 through the oil outlet and is returned to the compressor 413 through the oil path L7 and the refrigerant path L22.

[0156] The outdoor heat exchanger 415 performs heat exchange between the outside air and the refrigerant passing through its interior. Specifically, the outdoor heat exchanger 415 is equipped with a fan 417, and the outdoor heat exchanger 415 performs heat exchange between the outside air blown by the fan 417 and the refrigerant flowing through its interior.

[0157] During cooling operation of the air conditioner 400, the outdoor heat exchanger 415 causes the high-temperature, high-pressure refrigerant, which flows in from the refrigerant path L4 and is compressed by the compressor 413, to release heat to the outside air, and the condensed and liquefied refrigerant (liquid refrigerant) flows out into the refrigerant path L5.

[0158] Furthermore, during heating operation of the air conditioner 400, the outdoor heat exchanger 415 causes the low-temperature, low-pressure liquid refrigerant flowing in from the refrigerant path L5 to absorb heat from the outside air, and the evaporated refrigerant flows out into the refrigerant path L4.

[0159] The outdoor expansion valve 416 is closed to a predetermined degree during heating operation of the air conditioner 400, reducing the pressure of the refrigerant (liquid refrigerant) flowing in from the refrigerant path L6 to a predetermined pressure. On the other hand, the outdoor expansion valve 416 is fully open during cooling operation of the air conditioner 400, allowing the refrigerant (liquid refrigerant) to pass from the refrigerant path L5 to the refrigerant path L6. The outdoor expansion valve 416 is, for example, a solenoid valve.

[0160] The indoor unit 420 includes an indoor expansion valve 421, an indoor heat exchanger 422, and a fan 423.

[0161] During cooling operation of the air conditioner 400, the indoor expansion valve 421 is closed to a predetermined opening, reducing the pressure of the subcooled liquid refrigerant flowing in from the refrigerant path 440 to a predetermined pressure. On the other hand, during heating operation of the air conditioner 400, the indoor expansion valve 421 is fully open, allowing the refrigerant (liquid refrigerant) flowing out from the indoor heat exchanger 422 to pass towards the refrigerant path 440. The indoor expansion valve 421 is, for example, a solenoid valve.

[0162] The indoor heat exchanger 422 performs heat exchange between indoor air and the refrigerant passing through it. Specifically, the fan 423 mounted on the indoor unit 420 causes indoor air to pass around the indoor heat exchanger 422, promoting heat exchange between the air and the refrigerant inside the indoor heat exchanger 422. Then, the fan 423 causes the indoor air, which has undergone heat exchange with the refrigerant inside the indoor heat exchanger 422, to be sent outside the indoor unit 420, thereby achieving indoor cooling or heating.

[0163] The fan 423 includes an impeller 423A and a motor 100 that drives the impeller 423A. Thus, the motor drive system 1 can drive the fan 423 by driving the motor 100. The fan 423 is, for example, a cross-flow fan (also called a "through-flow fan"). Alternatively, the fan 423 may be other types of fans, such as a propeller fan (also called an "axial flow fan"), a centrifugal fan (also called a "turbo fan"), or a sirocco fan.

[0164] Furthermore, the components of the motor drive system 1 other than the motor 100, namely the power converter 200 and the control device 300, may all be mounted on the fan 423, or some or all of them may be provided outside the fan 423. In the latter case, the power converter 200 and the control device 300 may be mounted on the air conditioner 400, or they may be provided outside the air conditioner 400.

[0165] During cooling operation of the air conditioner 400, the indoor heat exchanger 422 lowers the temperature of the indoor air by allowing the low-temperature, low-pressure liquid refrigerant, which has been depressurized by the indoor expansion valve 421, to absorb heat from the indoor air.

[0166] On the other hand, during heating operation of the air conditioner 400, the indoor heat exchanger 422 causes the high-temperature, high-pressure refrigerant flowing in from the outdoor unit 410 through the refrigerant path 430 to release heat into the indoor air, thereby raising the temperature of the indoor air.

[0167] Thus, in this example, the air conditioner 400 includes a motor 100 driven by the motor drive system 1 according to this embodiment. Specifically, in the air conditioner 400, the compressor 413 and the fan 423 each include a motor 100 driven by the motor drive system 1. As a result, the motor drive system 1 can be applied to the air conditioner 400.

[0168] Furthermore, the motor drive system 1 according to this embodiment may be applied to the compressor of a refrigeration device other than the air conditioner 400. Other refrigeration devices include, for example, an air conditioner that is used as a cooling-only or heating-only unit, in which the four-way switching valve 411 described above is omitted. Other refrigeration devices may also be refrigeration devices other than air conditioners, such as water heaters, chiller units, or cooling devices that cool the air inside a storage area. The storage area refers to, for example, the inside of a refrigerator, freezer, display case, container, etc. Also, the motor drive system 1 according to this embodiment may be applied to a blower other than the blower applied to the refrigeration device, such as the fan 423 of the air conditioner 400 (for example, a fan of a ventilation device).

[0169] [Effect] The operation of the motor drive system, blower, compressor, and refrigeration system according to this embodiment will be described.

[0170] In a first aspect of this embodiment, the motor drive system drives a motor having a stator which includes a rotor containing a first permanent magnet, a stator core, and a plurality of coils wound around the stator core, and which is arranged radially opposite to the rotor. The motor drive system is, for example, the motor drive system 1 described above. The motor is, for example, the motor 100 described above. The rotor is, for example, the rotor 40 described above. The first permanent magnet is, for example, the permanent magnet 42 described above. The stator is, for example, the stator 30 described above. The stator core is, for example, the stator core 31 described above. The plurality of coils are, for example, the plurality of coils 32 described above. Specifically, the motor drive system comprises a current supply unit, a switching unit, and a control unit. The current supply unit is, for example, the power converter 200 described above. The switching unit is, for example, the switching unit 60 described above. The control unit is, for example, the control device 300 described above. More specifically, the current supply unit supplies current to the plurality of coils. Furthermore, the switching unit can switch between a first connection state and a second connection state regarding the connection state between the current supply unit and the plurality of coils. The control unit controls the current supply unit and the switching unit. The second connection state is a connection state in which the current supplied from the current supply unit is smaller than that in the first connection state when a predetermined current is passed through the plurality of coils. The control unit then performs a first control, which involves switching the connection state to the first connection state using the switching unit and supplying current to the plurality of coils using the current supply unit to rotate the rotor, and a second control, which involves switching the connection state to the second connection state using the switching unit and supplying current to the plurality of coils using the current supply unit to irreversibly change the residual magnetic flux density of the first permanent magnet.

[0171] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the first permanent magnet.

[0172] Furthermore, in a second aspect of this embodiment, based on the first aspect described above, the current supply unit may supply a three-phase alternating current to the plurality of coils. In the first connection state, the plurality of coils are connected to the current supply unit in a delta connection. In the second wiring configuration, the plurality of coils may be connected to the current supply unit in a Y-connection configuration.

[0173] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the first permanent magnet.

[0174] Furthermore, in a third aspect of this embodiment, based on the first aspect described above, the plurality of coils may include a first coil and a second coil. The first coil and the second coil are, for example, coil 32U1 and coil 32U2, coil 32V1 and coil 32V2, and coil 32W1 and coil 32W2. In the first connection state, the first coil and the second coil are connected to the current supply unit in parallel, and in the second connection state, the first coil and the second coil may be connected to the current supply unit in series.

[0175] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the first permanent magnet.

[0176] Furthermore, in a fourth aspect of this embodiment, assuming any one of the first to third aspects described above, in the first wiring state, the current supply unit and the plurality of coils are connected by a predetermined number of phases of three or more, and in the second wiring state, the current supply unit and the plurality of coils are connected by only a portion of the predetermined number of phases. The predetermined number of phases is, for example, the three phases of U, V, and W described above, and the portion of the predetermined number of phases is, for example, two of the U, V, and W phases described above.

[0177] This allows the motor drive system 1 to apply current to only some of the coils of a predetermined number of phases of the motor 100, thereby irreversibly changing the residual magnetic flux density of the first permanent magnet.

[0178] Furthermore, in a fifth aspect of this embodiment, based on any one of the first to fourth aspects described above, the control unit may, in the first control, supply current to three or more predetermined phases using the current supply unit, and in the second control, supply current to only some of the predetermined phases using the current supply unit.

[0179] This allows the motor drive system 1 to apply current to only some of the coils of a predetermined number of phases of the motor 100, thereby irreversibly changing the residual magnetic flux density of the first permanent magnet.

[0180] Furthermore, in a sixth aspect of this embodiment, based on any one of the first to fifth aspects described above, the control unit may perform a third control, in which it rotates the rotor by switching the wiring state to the second wiring state using the switching unit and supplying current to the plurality of coils using the current supply unit.

[0181] This allows the motor drive system to rotate the motor by selectively using a second connection state in addition to a first connection state between the current supply unit and the multiple coils.

[0182] Furthermore, in a seventh aspect of this embodiment, based on any one of the first to fifth aspects described above, the switching unit may be able to switch the connection state between the current supply unit and the plurality of coils between a first connection state, a second connection state, and a third connection state different from the first and second connection states. The control unit may then perform a fourth control, in which it switches the connection state to the third connection state using the switching unit and rotates the rotor by supplying current to the plurality of coils using the current supply unit. The first and third connection states are, for example, connection states in which the plurality of coils are connected in delta and Y connections, and the second connection state is a connection state in which only two of the three phases are connected to the current supply unit.

[0183] As a result, the motor drive system can rotate the motor 100 by selectively using the first and third wiring states, and can irreversibly change the residual magnetic flux density of the first permanent magnet using the second wiring state.

[0184] Furthermore, in the eighth aspect of this embodiment, based on any one of the first to third, sixth, and seventh aspects described above, the rotor may have a rotor core containing a soft magnetic material. The rotor core is, for example, the rotor core 41 described above. The first permanent magnet may also be embedded in the rotor core such that, in a cross section perpendicular to the rotation axis of the rotor, the magnetization direction is along the radial direction at a predetermined circumferential position. The rotation axis is, for example, the rotation axis AX described above. The control unit may, in the second control, switch the connection state to the second connection state using the switching unit, and control the current supply unit to supply current to the first phase coil, and to the second and third phase coils that are adjacent to the first phase coil in one and the other circumferential directions of the first phase coil, in a cross section perpendicular to the rotation axis, such that the magnetization direction of the first permanent magnet and the winding axis direction of the first phase coil of the stator among the plurality of coils substantially coincide. The first phase is, for example, the U phase in Figure 9 above, and the second and third phases are, for example, the V phase and the W phase in Figure 9 above.

[0185] This allows the motor drive system to irreversibly change the residual magnetic flux density of the first permanent magnet embedded in the rotor core such that the magnetization direction is along the radial direction.

[0186] Furthermore, in the ninth aspect of this embodiment, based on the fourth or fifth aspect described above, the rotor may have a rotor core containing a soft magnetic material. The rotor core is, for example, the rotor core 41 described above. The first permanent magnet may also be embedded in the rotor core such that, in a cross section perpendicular to the rotation axis of the rotor, the magnetization direction is inclined with respect to the radial direction at a predetermined circumferential position. The control unit may, in the second control, switch the connection state to the second connection state using the switching unit, and control the current supply unit to supply current to the first phase coil and the second phase coil so that, in a cross section perpendicular to the rotation axis, a hypothetical line drawn that bisects the angle between the q-axis of the rotor and the winding axes of the circumferentially adjacent first phase coil and second phase coil among the plurality of coils substantially coincides. The first phase and the second phase are, for example, the U phase and V phase in Figure 11 described above. The coils for the first phase and the coils for the second phase are, for example, coil 32U1 and coil 32V1 shown in Figure 11 above.

[0187] This allows the motor drive system to irreversibly change the residual magnetic flux density of the first permanent magnet embedded in the rotor core such that its magnetization direction is inclined with respect to the radial direction.

[0188] Furthermore, in the tenth aspect of this embodiment, based on any one of the first to ninth aspects described above, the rotor may include a second permanent magnet having a higher coercivity than the first permanent magnet.

[0189] This allows the motor drive system to maintain a constant level of magnetic flux with a second permanent magnet that has high coercivity, while irreversibly changing the residual magnetic flux density of the first permanent magnet, thereby adjusting the magnetic flux of the field including the first and second permanent magnets.

[0190] Furthermore, in the eleventh aspect of this embodiment, the blower comprises a motor driven by a motor drive system of any one of the first to tenth aspects described above, and a blower mechanism driven by the motor. The blower is, for example, the fan 423 described above. The blower mechanism is, for example, the impeller 423A described above.

[0191] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the permanent magnets in the motor mounted on the blower.

[0192] Furthermore, in the twelfth aspect of this embodiment, the compressor comprises a motor driven by a motor drive system of any one of the first to tenth aspects described above, and a compression mechanism driven by the motor. The compressor is, for example, the compressor 413 described above. The compression mechanism is, for example, the compression mechanism 413A described above.

[0193] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the permanent magnets in the motor mounted on the compressor.

[0194] Furthermore, in the 13th aspect of this embodiment, the refrigeration device comprises the motor driven by a motor drive system of any one of the first to tenth aspects described above. The refrigeration device is, for example, the air conditioner 400 or chiller described above.

[0195] This allows the motor drive system to suppress the current supplied to multiple coils when irreversibly changing the residual magnetic flux density of the permanent magnets in a motor mounted on a refrigeration unit.

[0196] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Explanation of Symbols]

[0197] 1. Motor drive system 30 staters 31 Stator Core 31A Back yoke section 31B Teeth section 32 coils 32U1, 32U2 coils 32V1, 32V2 coils 32W1, 32W2 coil 40 rotors 41 Rotor core 42 Permanent Magnets 42A, 42B Magnetic component 50 Rotation axis 60 Switching section 100 motor 150 power lines 150U U phase wire 150V V phase line 150W W phase line 200 Power converter 300 Control device 400 Air conditioner 410 Outdoor unit 411 Four-way switching valve 412 Accumulator 413 Compressor 413A Compression mechanism 414 Oil separator 415 Outdoor heat exchanger 416 Outdoor expansion valve 417 Fans 420 Indoor unit 421 Indoor expansion valve 422 Indoor heat exchanger 423 Fans 423A Impeller Ad d-axis Aq (q axis) Au winding shaft Auv bisector Av winding shaft AX Rotation axis center NP neutral point PS power supply

Claims

1. A motor drive system for driving a motor (100) having a rotor (40) including a first permanent magnet (42), and a stator (30) which includes a stator core (31) and a plurality of coils (32) wound around the stator core (31), and which is arranged radially opposite to the rotor (40), A current supply unit (200) that supplies current to the plurality of coils (32), A switching unit (60) is provided that can switch between a first connection state and a second connection state regarding the connection state between the current supply unit (200) and the plurality of coils (32). The system comprises a control unit (300) that controls the current supply unit (200) and the switching unit (60), The second wiring state is a wiring state in which, when a predetermined current is passed through the plurality of coils (32), the current supplied from the current supply unit (200) is smaller than that in the first wiring state. The control unit (300) is The first control involves switching the wiring state to the first wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40), The switching unit (60) switches the connection state to the second connection state, and the current supply unit (200) supplies current to the plurality of coils (32) to perform a second control that irreversibly changes the residual magnetic flux density of the first permanent magnet (42). Motor drive system.

2. The current supply unit (200) supplies a three-phase alternating current to the plurality of coils (32), In the first wiring configuration, the plurality of coils (32) are connected to the current supply unit (200) in a delta connection configuration. In the second wiring configuration, the plurality of coils (32) are connected to the current supply unit (200) in a Y-connection configuration. The motor drive system according to claim 1.

3. The plurality of coils (32) include a first coil (32U1, 32V1, 32W1) and a second coil (32U2, 32V2, 32W2), In the first wiring configuration, the first coils (32U1, 32V1, 32W1) and the second coils (32U2, 32V2, 32W2) are connected in parallel to the current supply unit (200). In the second wiring configuration, the first coils (32U1, 32V1, 32W1) and the second coils (32U2, 32V2, 32W2) are connected in series to the current supply unit (200). The motor drive system according to claim 1.

4. In the first wiring configuration described above, the current supply unit (200) and the plurality of coils (32) are connected in three or more predetermined phases. In the second wiring configuration, the current supply unit (200) and the plurality of coils (32) are connected by only some of the predetermined number of phases. A motor drive system according to any one of claims 1 to 3.

5. In the first control, the control unit (300) supplies current to three or more predetermined phases using the current supply unit (200), and in the second control, the current supply unit (200) supplies current to only some of the predetermined phases. A motor drive system according to any one of claims 1 to 3.

6. The control unit (300) performs a third control by switching the wiring state to the second wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40). A motor drive system according to any one of claims 1 to 3.

7. The switching unit (60) is capable of switching the connection state between the current supply unit (200) and the plurality of coils (32) between a first connection state, a second connection state, and a third connection state that is different from the first and second connection states. The control unit (300) performs a fourth control by switching the wiring state to the third wiring state using the switching unit (60) and supplying current to the plurality of coils (32) using the current supply unit (200) to rotate the rotor (40). A motor drive system according to any one of claims 1 to 3.

8. The rotor (40) has a rotor core (41) containing a soft magnetic material, The first permanent magnet (42) is embedded in the rotor core (41) such that, in a cross section perpendicular to the rotation axis (AX) of the rotor (40), the magnetization direction is along the radial direction at a predetermined circumferential position. In the second control, the control unit (300) switches the connection state to the second connection state using the switching unit (60), and controls the current supply unit (200) to supply current to the first phase coil (32U1) and the second phase coil (32V1) and third phase coil (32W1) that are adjacent to the first phase coil (32U1) in the circumferential direction, such that in a cross section perpendicular to the rotation axis (AX), the magnetization direction of the first permanent magnet (42) and the winding axis direction of the first phase coil (32U1) of the stator (30) among the plurality of coils (32) substantially coincide. A motor drive system according to any one of claims 1 to 3.

9. The rotor (40) has a rotor core (41) containing a soft magnetic material, The first permanent magnet (42) is embedded in the rotor core (41) such that, in a cross section perpendicular to the rotation axis (AX) of the rotor (40), the magnetization direction is inclined with respect to the radial direction at a predetermined circumferential position. In the second control, the control unit (300) switches the connection state to the second connection state using the switching unit (60), and controls the current supply unit (200) to supply current to the first phase coil (32U1) and the second phase coil (32V1) in a state where, in a cross section perpendicular to the rotation axis (AX), the q-axis of the rotor (40) and a hypothetical line drawn that bisects the angle between the winding axes of the first phase coil (32U1) and the second phase coil (32V1) that are adjacent in the circumferential direction among the plurality of coils (32) substantially coincide. The motor drive system according to claim 4.

10. A motor (100) driven by a motor drive system (1) according to any one of claims 1 to 3, The system includes a blower mechanism (423A) driven by the motor (100), Blower.

11. A motor (100) driven by a motor drive system (1) according to any one of claims 1 to 3, The system comprises a compression mechanism (413A) driven by the motor (100), Compressor.

12. The motor (100) is driven by the motor drive system (1) described in any one of claims 1 to 3. Refrigeration equipment.

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