JP6391358B2 - Electric motor system - Google Patents

Description

  The present invention relates to an electric motor system including an electric motor in which a rotor rotates while generating a magnetic force.

  A bearingless motor in which the motor part and the magnetic bearing part are magnetically integrated is an electric motor that rotates while the rotor generates magnetic force and floats. There are advantages of friction, no wear, and maintenance-free. Therefore, it is expected to be applied to centrifugal pumps that pump ultrapure water and chemicals used in semiconductor processes, cooling fans, centrifugal pumps for artificial hearts, stirrers for pio-reactors, flywheels for power storage, or oscillating stages. Has been

  In order to make the rotor magnetically levitated in the bearingless motor, the radial direction x and y, the axial direction z, and the tilt directions θx and θy other than the rotation direction θz of the rotor are made active or passive magnetic support force. Need to stabilize.

  In general, in the case of a single-axis control bearingless motor, only the axial direction z is actively controlled, and the radial directions x and y and the tilt directions θx and θy are passively stabilized using permanent magnets (for example, Non-patent document 1). Accordingly, only one displacement sensor is required to measure the axial direction z, and the number of inverters can be reduced, so that the cost is lower than that of a 2-axis control bearingless motor or a 5-axis control bearingless motor.

  Further, for example, as a single-axis control bearingless motor, there is a magnetic bearing motor in which passive magnetic bearings (PMB) are disposed at both ends of the motor and a thrust magnetic bearing is disposed at one end thereof (see, for example, Non-Patent Document 2). ).

  Similarly, there is a uniaxial control bearingless motor in which repulsive passive magnetic bearings (RPMB) are arranged at both ends of the motor (see Non-Patent Document 3, for example).

  Also, for example, an axial gap type single drive bearingless motor having a structure in which a motor and a passive magnetic bearing are integrated by increasing the axial length of a rotor and attaching a permanent magnet to a gap surface has been proposed. (For example, see Non-Patent Document 4). In this motor, only one type of winding is provided in the stator, and an active supporting force in the axial direction is generated by flowing d-axis current through the winding by one inverter, and q-axis current is generated. To generate rotational torque.

  In addition, for example, a single drive bearingless motor that can be driven by a single inverter has been proposed in which repulsive passive magnetic bearings (RPMB) are arranged at both ends of the motor to improve the rigidity in the radial and tilt directions. (For example, see Non-Patent Document 5.) According to this, although there is a problem that the unstable axial force increases as the rigidity in the passive stable direction increases, an active magnetic support force that overcomes the unstable force is generated by devising the motor structure itself. It is possible.

FIG. 27 is a cross-sectional view illustrating a single-axis control single drive bearingless motor having repulsive passive magnetic bearings at both ends of the motor. Hereinafter, the direction of the rotation axis of the rotor 10 is referred to as “z-axis direction” or simply “axial direction”. As illustrated in FIG. 27, the bearingless motor 1 includes a rotor 10 having a rotation axis in the z-axis direction and a stator 20 facing the rotor 10 with a gap in the radial direction. Passive magnetic bearings 30 are provided at the upper and lower ends of the shaft 14 that serves as the rotation axis (z-axis) of the rotor 10. The passive magnetic bearing 30 includes a rotor side permanent magnet 31 and a stator side permanent magnet 32. The rotor-side permanent magnet 31 and the stator-side permanent magnet 32 are configured with a radial gap arranged in the radial direction with the gap interposed therebetween. The rotor-side permanent magnet 31 is provided on the peripheral surface of the shaft 14 of the rotor 10. The stator side permanent magnet 32 is fixed to a case (not shown) to which the stator 20 is fixed, for example. The displacement sensor 51 detects the displacement of the rotor 10 in the z-axis direction, and the controller 52 controls the field current command i for controlling the position of the rotor 10 in the axial direction based on the position information detected by the displacement sensor 51. _q ^* is generated, and an armature current command i _d ^* for rotating the rotor 10 is generated. The three-phase inverter 53 converts the direct current based on the field current command i _q ^* and the armature current command i _d ^* and generates an alternating current for supplying to the winding. In the bearingless motor 1, the rotor torque is generated by the armature current (q-axis current), and the support force in the z-axis direction of the rotor is generated by the field current (d-axis current). As described above, in the single drive bearingless motor 1, active control and rotation control of the position of the rotor in the z-axis direction can be performed by one three-phase inverter 53.

  As described above, a cooling fan, a centrifugal pump for an artificial heart, and the like are considered as application fields of the single-axis control bearingless motor. However, in these fields, there is a restriction that the shaft length must be shortened. However, in general, a single-axis control bearingless motor is often designed to have a long shaft length for passive stabilization in the tilt directions θx and θy, and it is not easy to shorten the shaft length. In addition, vibration in the radial direction becomes large during the floating rotation of the rotor, and in the worst case, there is a risk of touchdown, and reducing the vibration in the radial direction and the tilt direction of the rotor is an issue. .

  As a method of reducing the radial vibration of the rotor, there are a method of increasing the rigidity of the rotor in the radial direction and generating a magnetic damping force for the rotor. By increasing the rigidity of the rotor in the radial direction, the vibration amplitude in the radial direction can be reduced. However, in the tilt direction, the moment of inertia decreases as the shaft length decreases, so the rigidity decreases, and vibration and displacement are reduced. There is a risk of growing.

  In order to suppress such vibration, there is a method of separately providing a three-phase inverter for vibration suppression in addition to a three-phase inverter for active control and rotation control of the z-axis direction position of the rotor. Hereinafter, since three-phase inverters are frequently used, three-phase will be described. However, it is well known to those skilled in the art that it can be equivalently converted to two-phase, and can be expanded to four or more phases. Is described. As an example, motor systems called neutral point injection type and motor winding parallel type will be described.

  FIG. 28 is a circuit diagram showing a neutral point injection type motor system having a three-phase inverter for vibration suppression, and FIG. 29 is a diagram illustrating a rotor structure for explaining the winding structure of the motor in the motor system of FIG. It is xy sectional drawing seen from the axial direction (+ z-axis direction). Here, as shown in FIG. 29, as the electric motor 1, the rotor 10 provided with the permanent magnet 11 has four poles, the stator 20 has six slots, and the windings are concentrated windings. The case will be described. The stator 20 is provided with a plurality of teeth 21-1 projecting toward the rotor 10 in the circumferential direction, and the teeth 21-1 are coupled via a yoke 21-2.

  FIG. 30 is a diagram showing the direction of the winding current, the direction of the force, the direction of the magnetic flux generated by the permanent magnet, and the direction of the magnetic flux generated by the winding current shown in the drawings of the present application. In the following drawings, the direction of the current flowing through the winding is indicated by a general notation method, and when the direction passing through from the back side of the paper to the front side is the “positive direction”, it is indicated by a circle with a black dot. The case where the direction penetrating from the front side to the back side of the paper surface is the “positive direction” is indicated by a circle with a cross. The direction of the magnetic flux generated by the permanent magnet (the direction of the magnetic flux from the north pole to the south pole as the magnetization direction of the permanent magnet) is indicated by a solid arrow, and the direction of the magnetic flux generated when a current flows through the winding Is indicated by a dashed arrow. The direction of the force is indicated by a white arrow. In addition, regarding the direction of the current flowing through the winding of each phase of the Y-connected three-phase winding, the direction flowing into the neutral point of the three-phase Y connection is defined as “positive direction”.

In addition to the three-phase inverter 53 for active control and rotation control of the z-axis direction position of the rotor, a three-phase inverter 153 for suppressing vibration is separately provided. In the neutral point injection type electric motor system shown in FIG. 28, a middle point is provided for each phase winding of the Y-connected three-phase windings, and each of these middle points is provided to a three-phase inverter 153 for suppressing vibration. Connected. A controller (not shown) is configured so that the field current and the armature current generated by the three-phase inverter 53 for active control and rotation control of the z-axis position of the rotor flow through the windings 22U ₁ , 22V ₁ , and 22W _1. ), The supporting currents i _su , i _sv and i _sw by the three-phase inverter 153 for suppressing vibration do not flow through the windings 22U ₁ , 22V ₁ and 22W ₁ , but the windings 22U ₂ and 22V. ₂ and 22W ₂ . Here, as shown in FIG. 28, consider the case of generating a radial force by passing a supporting current i _su from the three-phase inverter 153 for vibration suppression windings 22U ₂ in the X-axis direction in FIG. 29. In this case, support the current i _su of the U-phase flowing out from the three-phase inverter 153 for vibration suppression flows through the winding 22U ₂ through the midpoint of U-phase winding, are 2 further branches at a neutral point N ₁ It flows into the winding 22V ₂ and the winding 22W _2. That is, the V-phase supporting current i _sv flows from the neutral point N ₁ to the three-phase inverter 153 for vibration suppression via the winding 22V ₂ , and the W-phase supporting current i _sw is wound from the neutral point N ₁ to the winding. It flows to the three-phase inverter 153 for vibration suppression via 22W ₂ . Considering that the supporting currents i _su , i _sv and i _sw flow in the direction shown in FIG. 28 as described above, the windings 22U ₂ , 22V ₂ and 22W ₂ , and windings are provided in each slot as shown in FIG. Lines 22U ₁ , 22V ₁ and 22W ₁ are arranged. According to such a winding arrangement, occurs magnetic flux radially inward (+ x direction) in the tooth 21-1 windings 22U ₂ is wound by flowing through the winding 22U ₂ supporting current i _su, the magnetic flux in the teeth 21-1 windings 22V ₂ is wound by flowing through the winding 22V ₂ supporting current i _sv is generated radially outwardly, winding by flowing through the windings 22W ₂ supporting current i _sw magnetic flux is generated in a radially outward direction to the teeth 21-1 line 22W ₂ is wound. When the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 29, the magnetic flux density in the gap is made dense by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the support currents i _su , i _sv and i _sw. Occur. As a result, a radial force is generated in the + x direction. According to the winding arrangement shown in FIG. 29, if the direction and magnitude of the supporting currents i _su , i _sv, and i _sw flowing by the three-phase inverter 153 for suppressing vibration are appropriately controlled, the radius can be increased in all directions on the xy plane. Directional force can be generated.

  FIG. 31 is a circuit diagram showing a motor winding parallel type electric motor system having a three-phase inverter for vibration suppression, and FIG. 32 is a diagram illustrating the rotor structure of the rotor in the electric motor system of FIG. It is xy sectional drawing seen from the axial direction (+ z-axis direction). Here, as shown in FIG. 32, as the motor 1, the number of poles of the rotor 10 provided with the permanent magnets 11 is 4 and the number of slots of the stator 20 is 6 slots as in the above-described midpoint injection type. The case where the winding is configured by concentrated winding will be described. The stator 20 is provided with a plurality of teeth 21-1 projecting toward the rotor 10 in the circumferential direction, and the teeth 21-1 are coupled via a yoke 21-2.

In the motor winding parallel type electric motor system shown in FIG. 31, each phase between the three-phase inverter 53 for active control and rotation control of the z-axis direction position of the rotor and the three-phase inverter 153 for vibration suppression is provided. The windings are connected as follows. That is, the winding 22U ₁ and the winding 22U ₂ are connected in parallel for the U phase, the winding 22V ₁ and the winding 22V ₂ are connected in parallel for the V phase, and the winding 22W ₁ and the winding are connected for the W phase. The line 22W ₂ is connected in parallel. Winding 22U ₁ , winding 22V ₁ and winding 22W ₁ connected to three-phase inverter 53 are Y-connected via neutral point N ₁ . On the other hand, winding 22U ₂ , winding 22V ₂ and winding 22W ₂ are connected between three-phase inverter 53 and three-phase inverter 153. Therefore, the windings are connected in parallel when viewed from the three-phase inverter 53 side, and the windings are connected in series when viewed from the three-phase inverter 153 side. Under such a connection state of the windings, the supporting currents i _su , i _sv and i _sw by the three-phase inverter 153 for suppressing vibration are the winding 22U ₁ , the winding 22U ₂ , the winding 22V ₁ , the winding 22V ₂ , winding 22W ₁ and winding 22W ₂ all flow. Here, as shown in FIG. 31, consider the case of generating a radial force by passing a supporting current i _su from the three-phase inverter 153 for vibration suppression windings 22U ₂ in the X-axis direction in FIG. 32. In this case, support the current i _su of the U-phase flowing out from the three-phase inverter 153 for vibration suppression flows through winding 22U ₂ and the winding 22U _1, winding 22V ₁ and split into two further at a neutral point N ₁ It flows into the winding 22W _1. The V-phase support current i _sv flows from the neutral point N ₁ to the three-phase inverter 153 for vibration suppression via the winding 22V ₁ and the wire 22V ₂ , and the W-phase support current i _sw is the neutral point N _1. from via the winding 22W ₂ flows to the three-phase inverter 153 for vibration suppression. Thus, considering that the supporting currents i _su , i _sv and i _sw flow in the direction shown in FIG. 31, the windings 22U ₂ , 22V ₂ and 22W ₂ , and the windings are provided in each slot as shown in FIG. Lines 22U ₁ , 22V ₁ and 22W ₁ are arranged. According to such a winding arrangement, occurs magnetic flux radially outwardly (+ x direction) in the tooth 21-1 windings 22U ₂ is wound by flowing through the winding 22U ₂ supporting current i _su, the magnetic flux in the teeth 21-1 winding 22U ₁ is wound by flowing through the windings 22U ₁ support current i _su is generated radially inward (+ x direction). Further, generated in the magnetic flux in the radial direction to the tooth 21-1 windings 22V ₂ is wound by flowing through the winding 22V ₂ supporting current i _sv, supporting current i _sv to flow in the windings 22V ₁ magnetic flux is generated in a radially outward direction to the teeth 21-1 windings 22V ₁ is wound by. Further, generated in the magnetic flux in the radial direction to the tooth 21-1 windings 22W ₂ is wound by flowing through the windings 22W ₂ supporting current i _sw, supporting current i _sw to flow in the windings 22W ₁ magnetic flux is generated in a radially outward direction to the teeth 21-1 windings 22W ₁ is wound by. When the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 32, the magnetic flux density in the gap is made dense by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the support currents i _su , i _sv and i _sw. Occur. As a result, a radial force is generated in the + x direction. According to the winding arrangement shown in FIG. 32, if the direction and magnitude of the supporting currents i _su , i _sv, and i _sw flowing by the three-phase inverter 153 for suppressing vibration are appropriately controlled, the radius can be increased in all directions on the xy plane. Directional force can be generated. Further, since the supporting currents i _su , i _sv and i _sw flow through the winding 22U ₁ , the winding 22U ₂ , the winding 22V ₁ , the winding 22V ₂ , the winding 22W ₁ and the winding 22W _2. Magnetic flux is generated for all the lines, so that the motor winding parallel motor system can generate a greater radial force than the midpoint injection motor system.

T.A. T. Ohji, T. T. Katsuda, K. K. Amei, M.M. M. Sakui, “Structure of Surface-Attached Magnet Uniaxial Controlled Repulsive Magnetic Bearing System, and Its Levitation and Rotation Testing It's Levitation and Rotation Tests ", (USA), Institute of Electrical and Electronics Engineers (IEEE) Transactions, Magnetics, Vol. 47, no. 12, pp 4734-4739, December 2011 S. Yang, M. Huang, “Design and Implementation of a Magnetically Liberated Single-Axis Controlled Axis Controlled Axial Blood Pump ) "Institute of Electrical and Electronics Engineers (IEEE Transactions), Industrial Electronics, Vol. 56, no. 6, pp 2213-2219, June 2009 Yumoto Satoshi, Shinji Tadahiko, “Small Centrifugal Blood Pump with Axial Control Type Magnetic Bearing Motor”, Journal of the Japan Society of Mechanical Engineers, C, Vol. 78, No. 792, pp. 3064-3072, August 2012 J. et al. Asama (J. Asama), Y. Y. Hamasaki, T .; T. Oiwa, A. et al. A. Chiba, “A Novel Concept of a Single-Drive Bearingless Motor” (USA), Institute of Electrical and Electronics Engineers (IEEE Transactions), Industrial Electric (Industrial Electric) ), Vol. 60, no. 1, pp 129-138, January 2013 H. Sugimoto, S. Tanaka, A. Chiba, J. Asama, “The new cylindrical radial gap type single drive bearingless motor Design and Test Results of Novel Single-Driving Bearingless Motor with Cylindrical Radial Gap, IEEJ Energy Converter Conference and Expo (IEEE Energy Conx. 2466-2473, 2013

  When generating a radial force on the rotor, according to the neutral point injection type motor system and the motor winding parallel type motor system described above, active control and rotation control of the z-axis position of the rotor Therefore, it is necessary to provide at least two inverters, ie, a three-phase inverter for suppressing vibration and a three-phase inverter for suppressing vibration, which is expensive and requires a large installation space.

  Further, according to the neutral point injection type motor system and the motor winding parallel type motor system described above, it is possible to suppress the vibration in the radial direction of the rotor, but as described above, at least two inverters It is necessary to provide a high cost, and the installation space must be large.

  Further, according to the axial gap type single drive bearingless motor having a structure in which the motor and the passive magnetic bearing as described in Non-Patent Document 4 are integrated, the rotation of the rotor is driven by one inverter. Although it can support magnetic support, in order to stabilize the tilt direction, it is necessary to reduce the diameter of the rotor and increase the axial length. Therefore, the rigidity in the radial direction is low and it is difficult to shorten the axial length.

  Therefore, in view of the above problems, the first object of the present invention is to generate a radial force on the rotor with a single inverter and to generate a rotor torque and an active axial force. It is to provide a low-cost and space-saving electric motor system.

  In view of the above problems, the second object of the present invention is to suppress the radial vibration of the rotor with a single inverter and to generate the rotor torque and the active axial force. It is to provide a low-cost and space-saving electric motor system.

  In order to achieve the above object, in the present invention, in the motor system, permanent magnets are arranged so that a radially outward magnetic flux and a radially inward magnetic flux are alternately generated in the circumferential direction with respect to the rotating shaft. A multiphase winding in which a rotor and a stator opposed to the rotor with a gap in the radial direction are provided, and a plurality of teeth projecting toward the rotor are provided in the circumferential direction and connected in a neutral point. A stator coil of each phase of which is arranged between each tooth, and an electric motor that converts an input DC current and supplies the stator coil with an AC current An inverter, a connecting means for connecting the midpoint of the DC side voltage of the inverter and one of the neutral points of the multiphase winding, and a controller for controlling the inverter so that a zero-phase current flows through the connecting means; The connection means By a magnetic flux generated by the magnetic flux and the permanent magnet generated by passing a zero-phase current, generates a radial force to the rotor.

  Further, the electric motor system includes a sensor that detects radial vibration from the central axis of the rotor, and the controller performs radial force in a direction that suppresses vibration of the rotor based on information about vibration detected by the sensor. A zero-phase current command for controlling the inverter is generated so that the zero-phase current for generating the current flows to the control means.

  Here, in each phase of the multiphase winding, the stator winding may be composed of a set of windings connected in parallel to each other. In this case, the winding set connected in parallel to each other in each phase. The neutral point when one set is Y-connected is connected to the midpoint of the voltage on the DC side of the inverter by connecting means, and each winding set is a zero-phase current flowing through the neutral point. Are arranged between the teeth so that a radial force in one direction is generated on the rotor by the magnetic flux generated by the permanent magnet and the magnetic flux generated by the permanent magnet.

Further, the motor, the number of poles of the rotor p _r, the number of poles of the magnetic field generated when a current of zero-phase current to the stator windings when the p _s, in the "p _s = p _r ± 2" It has a rotor, a stator and a winding that satisfy the relational expression expressed.

  According to the present invention, a low-cost and space-saving electric motor capable of generating a radial force on a rotor with a single inverter and capable of generating a rotor torque and an active axial force. A system can be realized. That is, according to the present invention, the connecting means connects the midpoint of the voltage on the DC side of the three-phase inverter and one of the neutral points of the Y-connected three-phase winding provided in the stator winding. The magnetic flux is generated in the stator winding by flowing a zero-phase current through the connecting means, and the radial force is generated on the rotor by the magnetic flux and the magnetic flux generated by the permanent magnet. it can. Since the zero-phase current is alternating current, there is an advantage that voltage unbalance is less likely to occur at the neutral point, but the divided voltage may be controlled.

  Further, according to the present invention, a single inverter can suppress the vibration of the radial force of the rotor and can generate the torque of the rotor and the active axial force. The electric motor system can be realized. That is, according to the present invention, the zero-phase current that flows through the connecting means is adjusted according to the radial vibration from the central axis of the rotor, so that a radial force that suppresses the radial vibration of the rotor is generated. Can be made. The present invention can also be applied to vibration suppression in a general motor radial direction that does not need to generate an active axial force.

1 is a circuit diagram showing an electric motor system according to a first embodiment of the present invention. FIG. 2 is an xy sectional view illustrating a winding structure of an electric motor in the electric motor system of FIG. 1 as viewed from the axial direction of a rotor (+ z-axis direction). It is xy sectional drawing seen from the axial direction (+ z-axis direction) of the rotor explaining the modification of the winding structure of the electric motor of the electric motor system by 1st Example of this invention. 1 illustrates a winding structure in which the number of rotor poles of the motor in the motor system of FIG. 1 is four and the number of magnetic field poles generated when a zero-phase current is passed through the stator winding is two. FIG. 4 is an xy sectional view as seen from the axial direction (+ z-axis direction) of the rotor. It is a circuit diagram which shows the electric motor system by the 2nd Example of this invention. FIG. 6 is an xy cross-sectional view illustrating the winding structure of the electric motor in the electric motor system of FIG. 5 as viewed from the axial direction (+ z-axis direction) of the rotor. It is a circuit diagram which shows the electric motor system by the 3rd Example of this invention. FIG. 8 is an xy sectional view illustrating the winding structure of the electric motor in the electric motor system of FIG. 7 as viewed from the axial direction (+ z-axis direction) of the rotor. It is a circuit diagram which shows the electric motor system by the 4th Example of this invention. FIG. 10 is an xy cross-sectional view illustrating the winding structure of the electric motor in the electric motor system of FIG. 9 as viewed from the axial direction (+ z-axis direction) of the rotor. It is a circuit diagram which shows the electric motor system by the 5th Example of this invention. FIG. 12 is an xy sectional view illustrating the winding structure of the motor in the motor system of FIG. 11 as viewed from the axial direction (+ z-axis direction) of the rotor. It is a disassembled perspective view explaining the electric motor in the electric motor system by the 6th Example of this invention. It is xz sectional drawing of the electric motor in the electric motor system of FIG. It is a control block diagram explaining the electric motor system which has the electric motor of FIG. 13 and FIG. It is xz sectional drawing explaining the generation | occurrence | production principle of the axial force of the electric motor in the electric motor system of FIG. It is xz sectional drawing explaining the generation | occurrence | production principle of the radial direction force in the 6th Example of this invention. It is xy sectional drawing seen from the axial direction (+ z-axis direction) of the rotor which illustrates the winding structure of the electric motor in the electric motor system of FIGS. 13-17, (A) is the upper stage of three layers, (B) Indicates the middle of the three layers, and (C) indicates the lower of the three layers. It is a figure explaining suppression of the radial vibration of the rotor of the bearingless motor in the electric motor system in the 1st example of the present invention. It is a figure which shows the production | generation of the command value which suppresses the primary vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in 1st Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the radial fourth-order vibration of the rotor of the bearingless motor in the electric motor system in 1st Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the primary vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in the 3rd Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the secondary vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in the 3rd Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the primary vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in 4th Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the secondary vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in 4th Example of this invention. It is a figure which shows the production | generation of the command value which suppresses the 6th vibration of the radial direction of the rotor of the bearingless motor in the electric motor system in the 4th Example of this invention. It is sectional drawing explaining the single drive bearingless motor of 1 axis control which has a repulsive passive magnetic bearing in the both ends of a motor. It is a circuit diagram showing a neutral point injection type electric motor system having a three-phase inverter for vibration suppression. It is xy sectional drawing seen from the axial direction (+ z-axis direction) of the rotor explaining the winding structure of the electric motor in the electric motor system of FIG. It is a figure which shows the direction of the winding current shown in this-application drawing, the direction of force, the direction of the magnetic flux generated by a permanent magnet, and the direction of the magnetic flux generated by a winding current. It is a circuit diagram showing a motor winding parallel type electric motor system having a three-phase inverter for vibration suppression. FIG. 32 is an xy cross-sectional view illustrating the winding structure of the electric motor in the electric motor system of FIG. 31 as viewed from the axial direction (+ z-axis direction) of the rotor.

  A bearingless motor according to the present invention will be described below with reference to the drawings. However, it should be understood that the invention is not limited to the drawings or the embodiments described below. Hereinafter, an inner rotor type will be described as an example, but an outer rotor type may be used. Hereinafter, since three-phase inverters are frequently used, three-phase inverters are described, but multi-phase inverters such as two-phase or four-phase or more may be used. Further, it may be a general motor having a mechanical bearing instead of a bearingless motor.

  FIG. 1 is a circuit diagram showing an electric motor system according to a first embodiment of the present invention, and FIG. 2 is an axial direction of a rotor (+ z-axis direction) illustrating a winding structure of the electric motor in the electric motor system of FIG. It is xy sectional drawing seen from ().

  According to the first embodiment of the present invention, an electric motor system 100 includes an electric motor (hereinafter referred to as “bearingless motor”) 1, a three-phase inverter 2, connection means 3, a controller (not shown), Is provided.

The bearingless motor 1 includes a rotor 10 and a stator 20 that faces the rotor 10 with a gap in the radial direction. Bearingless motor 1, when the number of poles p _r of the rotor 10, the number of poles of the magnetic field generated when a current of zero-phase current to the stator windings provided on the stator 20 and the p _s, Equation 1 Shall be satisfied. As an example, in the first embodiment of the present invention, the number of poles p _r of the rotor 20 and 4-pole, 6-pole to pole p _s of the magnetic field generated when a current of zero-phase current to the stator winding It is said. Note that the number of slots of the stator 20 is not particularly limited as long as the number functions as a general motor. In the first embodiment of the present invention, the number of slots of the stator 20 is set to 6, for example.

In the rotor 10, the permanent magnet 11 is arranged so that a radially outward magnetic flux and a radially inward magnetic flux are alternately generated in the circumferential direction with respect to the rotation axis z. In the stator 20, a plurality of teeth 21-1 protruding toward the rotor 10 are provided in the circumferential direction, and the stator windings 22 U ₁ , 22 U ₂ , 22 V of each phase of a three-phase winding connected in a neutral point. ₁ , 22V ₂ , 22W ₁ and 22W ₂ are arranged between the teeth 21-1.

In each phase, the stator windings are divided so as to be connected in parallel with each other. In the case of a three-phase winding, the parallel number is a divisor of the number of slots of the stator 20 divided by three. However, when the number of slots is greater than 3, the parallel number 1 is not included. For example, in this embodiment, since the number of slots is 6, the number of parallel stator windings is set to 2 for each phase, for example. Some specific examples of the parallel number other than the present embodiment will be described later. As shown in FIG. 1, the stator winding of each phase in the stator 20 is divided into two so as to be connected in parallel with each other, and one stator winding is Y-connected like a general three-phase motor. It is connected to the neutral point N ₁ when it is, the other stator windings are connected to the neutral point N ₂ which is connected to the midpoint of the voltage of the DC side of the three-phase inverter 2. That is, in each phase of the three-phase winding of the electric motor 1, the stator winding is a set of windings connected in parallel, the stator windings 22U ₁ and 22U ₂ , 22V ₁ and 22V ₂ , 22W ₁ and 22W. ₂ The neutral point N ₂ when one of the winding sets connected in parallel to each other is Y-connected is connected to the midpoint of the voltage on the DC side of the three-phase inverter 2 by the connecting means 3. As shown in FIG. 2, in the first embodiment of the present invention, each winding group is composed of a rotor by a magnetic flux generated by a zero-phase current flowing through a neutral point N ₂ and a magnetic flux generated by a permanent magnet 11. 10 is arranged between the teeth 21-1 so that a radial force in one direction is generated.

The three-phase inverter 2 converts the input direct current to generate a three-phase alternating current to be supplied to the stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ .

Connecting means 3, and the midpoint of the midpoint i.e. DC capacitor of the DC side voltage of the three-phase inverter 2, in one of the neutral point N ₁ and N ₂ having three-phase windings of the bearingless motor 1 A certain N ₂ is connected.

  The controller controls the three-phase inverter so that a zero-phase current flows through the connection means 3. In the present invention, a radial force is generated on the rotor 10 by the magnetic flux generated by flowing a zero-phase current through the connecting means 3 and the magnetic flux generated by the permanent magnet 11. The operation principle will be described below.

In a general three-phase motor, as shown in Equation 2, the sum of the three-phase currents i _u , i _v and i _w flowing into the motor is zero (0).

On the other hand, according to the first embodiment of the present invention shown in FIG. 1, the relationship between the three-phase currents i _u , _iv and i _w and the zero-phase current i ₀ is expressed by Equation 3.

Normally, when the torque of the rotor 10 and the magnetic support force in the z-axis direction are generated, the zero-phase current i ₀ in Equation 3 is 0A. For example, regarding the U phase, the motor current flows through both of the stator windings 22U ₁ and 22U ₂ connected in parallel to each other, but the zero phase current i ₀ does not flow. When the zero-phase current i ₀ flows through the connecting means 3, the zero-phase currents i _u0 , i _v0 and i _w0 flowing through the stator windings 22U ₂ , 22V ₂ and 22W ₂ satisfy the relational expression of Expression 4.

In FIG. 1, when a positive zero-phase current i ₀ is flowed, the switches S ₁ , S _3, and S ₅ of the upper arm of the three-phase inverter 2 are turned on by control of the controller, so Zero-phase currents i _u0 , i _v0 and i _w0 flow only in the stator windings 22U ₂ , 22V ₂ and 22W ₂ connected to the point N ₂ , respectively. As a result, as shown in FIG. 2, the magnetic flux radially inward to teeth 21-1 is the stator winding 22U ₂ wound by flowing zero-phase current i _u0 in the stator windings 22U ₂ (+ x-direction ) And a zero-phase current i _v0 flows through the stator winding 22V ₂ , so that magnetic flux is generated radially inward in the teeth 21-1 around which the stator winding 22V ₂ is wound. the magnetic flux in the teeth 21-1 is the stator winding 22W ₂ is wound by the 22W ₂ flows zero-phase current i _w0 is generated radially inward. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 2, the magnetic flux density of the gap is reduced by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0. Occurs. As a result, a radial force F _r is generated in the + x direction.

Conversely, if the flow negative zero-phase current i ₀ 1, by turning on the switch S _2, S ₄ and S ₆ of the lower arm of the three-phase inverter 2 under control of the controller, the connection means 3 Zero-phase currents i _u0 , i _v0, and i _w0 flow only in the stator windings 22U ₂ , 22V _2, and 22W ₂ connected to the neutral point N ₂ . As a result, a magnetic flux in the direction opposite to the direction shown in FIG. 2 is generated in each tooth 21-1, and the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0 are As a result, the magnetic flux density in the gap becomes coarse and dense. As a result, a radial force is generated in the −x direction, which is opposite to the direction shown in FIG.

Here, the case where the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 2 has been described as an example. However, since the rotor 10 rotates around the rotation axis z, the radial force F _r is a bearingless motor. It rotates in synchronization with the electrical angle of 1.

Thus, according to the first embodiment of the present invention, the radial force applied to the rotor 10 by the magnetic flux generated by flowing the zero-phase current through the connecting means 3 and the magnetic flux generated by the permanent magnet 11. F _r can be generated. The direction and magnitude of the radial force F _r can be controlled by appropriately controlling the alternating zero-phase current flowing through the connecting means 3 by the controller. Since the fine current i ₀ is alternating current, there is an advantage that voltage imbalance is unlikely to occur at the neutral point N ₂ . If necessary, the divided voltage may be controlled.

FIG. 3 is an xy sectional view as viewed from the axial direction of the rotor (+ z-axis direction) for explaining a modification of the winding structure of the motor of the motor system according to the first embodiment of the present invention. In FIG. 3, the permanent magnet 11 is shown for the rotor 10, and only the windings and the teeth 21-1 are shown for the stator 20, and the other parts are omitted. In the motor system shown in FIG. 1, when the stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ are arranged at the positions shown in FIG. 3, the winding structure shown in FIG. The radial force can be generated in the same direction as the case.

FIG. 4 shows a winding when the number of poles of the rotor of the motor in the motor system of FIG. 1 is four and the number of poles of the magnetic field generated when a zero-phase current is passed through the stator winding is two. It is xy sectional drawing seen from the axial direction (+ z-axis direction) of the rotor which illustrates a structure. In FIG. 4, the permanent magnet 11 is shown for the rotor 10, and only the windings and the teeth 21-1 are shown for the stator 20, and the other parts are omitted. As described above, the bearingless motor 1 to which the present invention can be applied satisfies Equation 1, but here, as the bearingless motor 1 satisfying Equation 1, the number of rotor poles _pr is 4 and the stator is fixed. An example in which the number of poles p _s of the magnetic field generated when a zero-phase current is passed through the winding is two will be described. For example, when the stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ are arranged at the positions shown in FIG. 4, the stator windings 22U ₂ , 22V ₂ and 22W ₂ flows positive zero-phase current, teeth flux in the teeth 21-1 stator winding 22U ₂ is wound occurs radially outwardly (+ x direction), the stator winding 22V ₂ is wound 21 The magnetic flux is generated outward in the radial direction 1, and the magnetic flux is generated outward in the radial direction in the teeth 21-1 around which the stator winding 22 </ _b > W ₂ is wound. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 4, the magnetic flux density of the gap is coarsely and densely generated by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by each zero-phase current. As a result, a radial force F _r is generated in the + x direction. As described above, the present modification is a quadrupole rotor as in the first embodiment shown in FIG. 1, but the number of magnetic poles p _s generated when a zero-phase current is passed through the stator winding. If the number of poles of the magnetic field generated when a zero-phase current is passed through the stator winding is different, the winding arrangement is changed as shown in this modification.

FIG. 5 is a circuit diagram showing an electric motor system according to a second embodiment of the present invention, and FIG. 6 is an axial direction of the rotor (+ z axial direction) illustrating the winding structure of the electric motor in the electric motor system of FIG. It is xy sectional drawing seen from (). In FIG. 6, only the windings and the teeth 21-1 are shown for the permanent magnet 11 and the stator 20 for the rotor 10, and the other parts are omitted. In this embodiment, the present invention is applied to a bearingless motor 1 that satisfies Equation 1 in which the number of poles of the rotor is two and the number of poles of the magnetic field generated when a zero-phase current is passed through the stator winding is zero. It is applied. For the bearingless motor 1, as shown in FIG. 6, the number of slots (that is, the number of teeth 21-1) is 3, so that each tooth 21-1 includes a stator winding 22U ₁ , a stator winding 22V ₁ and The stator winding 22W ₁ is wound. Further, as shown in FIG. 5, Y-connected stator windings 22U _1, the neutral point N ₁ of the stator winding 22V ₁ and stator windings 22W ₁ is, by connecting means 3, the three-phase inverter 2 Is connected to the midpoint of the DC side voltage. Flowing a positive zero phase current i ₀ 5, as shown in FIG. 6, the teeth 21-1 is the stator winding 22U ₁ is wound by flowing zero-phase current i _u0 to the stator coil 22U ₁ magnetic flux radially outwardly to (+ x direction) occurs, the magnetic flux in the teeth 21-1 is the stator winding 22V ₁ wound by flowing zero-phase current i _v0 to the stator coil 22V ₁ is the radius occurs outwardly, a magnetic flux is generated in a radially outward direction to the teeth 21-1 is the stator winding 22W ₁ wound by the zero-phase current i _w0 to the stator coil 22W ₁ flows. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 6, the magnetic flux density of the gap is _roughly reduced by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0. Occurs. As a result, a radial force F _r is generated in the + x direction.

FIG. 7 is a circuit diagram showing an electric motor system according to a third embodiment of the present invention, and FIG. 8 is an axial direction of a rotor (+ z-axis direction) illustrating the winding structure of the electric motor in the electric motor system of FIG. It is xy sectional drawing seen from (). In FIG. 8, only the windings and the teeth 21-1 are shown for the permanent magnet 11 and the stator 20 for the rotor 10, and other parts are omitted. In the present embodiment, the present invention is applied to a bearingless motor 1 that satisfies Equation 1 in which the number of poles of the rotor is 6 and the number of magnetic fields generated when a zero-phase current is passed through the stator winding is 4. It is applied. As such a bearingless motor 1, the number of slots of the stator 20 (that is, the number of teeth 21-1) is, for example, 9 and 18, but here, the number of slots is 9 as shown in FIG. . As described above, in the case of a three-phase winding, the parallel number of the stator windings 20 in each phase is a divisor of the number obtained by dividing the number of slots of the stator 20 by 3, but in this embodiment, the number of slots is Since it is 9, the parallel number of the stator windings is set to 3 in each phase, for example. That is, in order to wind the stator winding around the nine teeth 21-1, the stator winding is divided into three parts in each phase of the stator 20 so as to be connected in parallel with each other. In each phase, two stator windings of the winding set are connected to a neutral point N ₁ when Y-connected as in a general three-phase motor, and another stator winding. Is connected to a neutral point N ₂ connected to the midpoint of the power supply on the DC side of the three-phase inverter 2. That is, as shown in FIG. 7, the stator windings 22U _2, the neutral point N ₂ of the stator winding 22V ₂ and stator windings 22W ₂ is a connecting means 3, the three-phase inverter 2 of the DC side The middle point of the voltage is connected, and the two parallel stator windings 22U ₁ , the two parallel stator windings 22V ₁ and the two parallel stator windings 22W ₁ are connected to the neutral point N ₁ . The stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ having such a connection relationship are wound around the teeth 21-1 in the positional relationship as shown in FIG. 8, for example. Flowing a positive zero-phase current i ₀ in FIG. 7, as shown in FIG. 8, the teeth 21-1 is the stator winding 22U ₂ wound by flowing zero-phase current i _u0 the stator winding 22U ₂ magnetic flux radially outwardly to (+ x direction) occurs, the magnetic flux in the teeth 21-1 is the stator winding 22V ₂ wound by flowing zero-phase current i _v0 the stator winding 22V ₂ is the radius occurs outwardly, a magnetic flux is generated in a radially outward direction to the teeth 21-1 is the stator winding 22W ₂ is wound by the zero-phase current i _w0 the stator winding 22W ₂ flows. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 8, the magnetic flux density of the gap is _roughly reduced by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0. Occurs. As a result, a radial force F _r is generated in the + x direction.

FIG. 9 is a circuit diagram showing an electric motor system according to a fourth embodiment of the present invention, and FIG. 10 is an axial direction of a rotor (+ z axis direction) illustrating the winding structure of the electric motor in the electric motor system of FIG. It is xy sectional drawing seen from (). In FIG. 10, only the windings and the teeth 21-1 are shown for the permanent magnet 11 and the stator 20 for the rotor 10, and other parts are omitted. This embodiment is a bearingless motor 1 that satisfies Equation 1 in which the number of poles of the rotor is 8 and the number of magnetic fields generated when a zero-phase current is passed through the stator winding is 6. The invention is applied. As such a bearingless motor 1, the number of slots of the stator 20 (that is, the number of teeth 21-1) includes, for example, 6, 12, 18 and the like. Here, as shown in FIG. It is said. As described above, in the case of a three-phase winding, the parallel number of the stator windings 20 in each phase is a divisor of the number obtained by dividing the number of slots of the stator 20 by 3, but in this embodiment, the number of slots is Since it is 12, in each phase, the parallel number of the stator windings is, for example, 4. That is, in order to wind the stator winding around the 12 teeth 21-1, the stator winding is divided into four parts in each phase of the stator 20 so as to be connected in parallel with each other. In each phase, three stator windings of the winding set are connected to a neutral point N ₁ when Y-connected as in a general three-phase motor, and another stator winding. Is connected to a neutral point N ₂ connected to the midpoint of the DC side voltage of the three-phase inverter 2. That is, as shown in FIG. 9, the stator winding 22U _2, the neutral point N ₂ of the stator winding 22V ₂ and stator windings 22W ₂ is a connecting means 3, the three-phase inverter 2 of the DC side The middle point of the voltage is connected, and the three parallel stator windings 22U ₁ , the three parallel stator windings 22V ₁ and the three parallel stator windings 22W ₁ are connected to the neutral point N ₁ . The stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ having such a connection relationship are wound around the teeth 21-1 in the positional relationship as shown in FIG. Flowing a positive zero-phase current i ₀ 9, as shown in FIG. 10, the teeth 21-1 is the stator winding 22U ₂ wound by flowing zero-phase current i _u0 the stator winding 22U ₂ magnetic flux radially outwardly to (+ x direction) occurs, the magnetic flux in the teeth 21-1 is the stator winding 22V ₂ wound by flowing zero-phase current i _v0 the stator winding 22V ₂ is the radius occurs outwardly, a magnetic flux is generated in a radially outward direction to the teeth 21-1 is the stator winding 22W ₂ is wound by the zero-phase current i _w0 the stator winding 22W ₂ flows. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 10, the magnetic flux density of the gap is _roughly reduced by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0. Occurs. As a result, a radial force F _r is generated in the + x direction.

FIG. 11 is a circuit diagram showing an electric motor system according to a fifth embodiment of the present invention, and FIG. 12 is a diagram illustrating a winding structure of the electric motor in the electric motor system of FIG. It is xy sectional drawing seen from (). In FIG. 12, only the windings and the teeth 21-1 are shown for the permanent magnet 11 and the stator 20 for the rotor 10, and the other parts are omitted. This embodiment is a bearingless motor 1 that satisfies Equation 1 in which the number of poles of the rotor is 10 and the number of poles of the magnetic field generated when a zero-phase current is passed through the stator winding is 12. The invention is applied. As shown in FIG. 12, the bearingless motor 1 has 12 slots (that is, the number of teeth 21-1). As described above, in the case of a three-phase winding, the parallel number of the stator windings 20 in each phase is a divisor of the number obtained by dividing the number of slots of the stator 20 by 3, but in this embodiment, the number of slots is Since it is 12, in each phase, the parallel number of the stator windings is, for example, 4. That is, in order to wind the stator winding around the 12 teeth 21-1, the stator winding is divided into four parts in each phase of the stator 20 so as to be connected in parallel with each other. In each phase, the three stator windings of the winding set are connected to the neutral point N ₂ connected to the midpoint of the DC side voltage of the three-phase inverter 2 and another fixed The child winding is connected to a neutral point N ₁ when Y-connection is performed as in a general three-phase motor. That is, as shown in FIG. 11, 3 parallel stator winding 22U _2, 3 parallel stator winding 22V ₂ and 3 parallel neutral point N ₂ of the stator winding 22W ₂ is a connection means 3 The stator winding 22U ₁ , the stator winding 22V ₁ and the stator winding 22W ₁ are connected to the neutral point N ₁ . The stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ having such a connection relationship are wound around the teeth 21-1 in the positional relationship as shown in FIG. 12, for example. Flowing a positive zero-phase current i ₀ 11, as shown in FIG. 12, the teeth 21-1 is the stator winding 22U ₂ wound by flowing zero-phase current i _u0 the stator winding 22U ₂ magnetic flux radially outwardly to (+ x direction) occurs, the magnetic flux in the teeth 21-1 is the stator winding 22V ₂ wound by flowing zero-phase current i _v0 the stator winding 22V ₂ is the radius occurs outwardly, a magnetic flux is generated in a radially outward direction to the teeth 21-1 is the stator winding 22W ₂ is wound by the zero-phase current i _w0 the stator winding 22W ₂ flows. Therefore, when the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 12, the magnetic flux density of the gap is _roughly reduced by the magnetic flux generated by the permanent magnet 11 and the magnetic flux generated by the zero-phase currents i _s0 , i _s0 and i _s0. Occurs. As a result, a radial force F _r is generated in the + x direction.

  Note that the number of poles of the rotor and the number of slots of the stator in the first to fifth embodiments described above are merely examples, and the present invention is not particularly limited thereto. The present invention can be applied to any bearingless motor that satisfies Formula 1.

  In the above-described first to fifth embodiments, the winding structure of the bearingless motor has been described using the xy cross-sectional view as seen from the axial direction (+ z-axis direction) of the rotor. In each of these embodiments, when viewed from the xz cross section, the rotor includes a first permanent magnet that generates a magnetic flux radially outward with respect to the rotation axis and a second permanent magnet that generates a magnetic flux radially inward. Are considered to have one permanent magnet layer that is alternately provided in the circumferential direction on the same xy plane. However, the present invention can be realized without being limited to the number of permanent magnet layers of the stator. That is, as in the sixth embodiment described with reference to FIGS. 14 to 18, a multilayer structure having a plurality of permanent magnet layers stacked in the axial direction can be used. Here, as an example, a case where three permanent magnet layers are stacked will be described.

  FIG. 13 is an exploded perspective view for explaining an electric motor in an electric motor system according to a sixth embodiment of the present invention, and FIG. 14 is an xz sectional view of the electric motor in the electric motor system of FIG. 14 and FIG. 15 and FIG. 17 described later show an xz cross section cut at a portion where the U-phase winding exists as an example. As an example, a bearingless motor 1 having a surface-attached rotor in which a 12-slot stator is provided with 8-pole concentrated winding will be described.

  The rotor 10 has a structure in which three permanent magnet layers including a permanent magnet 11 in which a radially outward magnetic flux and a radially inward magnetic flux are alternately generated in the circumferential direction with respect to the rotation axis z are laminated. Between the permanent magnets 11 included in each permanent magnetic flux layer adjacent in the axial direction, a layer of a nonmagnetic material 12 made of a nonmagnetic material is provided. A displacement sensor 51 that detects the position of the rotor 10 in the axial direction is provided in the vicinity of the rotation axis of the rotor 10. Passive magnetic bearings (PMB) 30 that passively magnetically support the rotor 10 in the radial direction with respect to the stator 20 are provided at both upper and lower ends of the shaft 14 that serves as the rotation axis z of the rotor 10. . The passive magnetic bearing 30 includes a rotor side permanent magnet 31 and a stator side permanent magnet 32. The rotor-side permanent magnet 31 is provided on the peripheral surface of the shaft 14 of the rotor 10. The stator side permanent magnet 32 is fixed to a case (not shown) to which the stator 20 is fixed, for example. The rotor-side permanent magnet 31 and the stator-side permanent magnet 32 may be either one that attracts or repels each other. In the illustrated example, a repulsive passive magnetic bearing 30 is shown. In this case, the rotor-side permanent magnet 31 and the stator-side permanent magnet 32 are configured by a radial gap arranged in the radial direction with a gap interposed therebetween. Although not shown, in the case of an attraction-type passive magnetic bearing, the rotor-side permanent magnet 31 and the stator-side permanent magnet 32 are configured by an axial gap arranged in the axial direction with a gap interposed therebetween.

  In the stator 20, a plurality of auxiliary teeth 23-1 projecting toward the rotor 10 are provided on the outer ends of the stator core 21 in the Z-axis direction in the circumferential direction. The teeth 21-1 and the auxiliary teeth 23-1 are coupled by a yoke 23-2. A winding (hereinafter referred to as “auxiliary winding”) 24U is wound around the auxiliary teeth 23-1. As a result, it is possible to further increase the force generated in the Z-axis direction by causing a current to flow through the auxiliary winding 24U in addition to the winding 22U.

  Regarding the bearingless motor 1 having the structure shown in FIGS. 13 and 14, before explaining the principle of generating the radial force of the rotor 10, the principle of generating the torque of the rotor 10 and the supporting force in the z-axis direction will be described. The explanation is as follows.

  FIG. 15 is a control block diagram for explaining an electric motor system having the electric motors of FIGS. 13 and 14. As shown in FIG. 15, the electric motor system 100 includes the bearingless motor 1 shown in FIGS. 13 and 14, a displacement sensor 51 that detects the axial position of the rotor, and position information that the displacement sensor 51 detects. Based on the controller 52 for generating a field current command for controlling the axial position of the rotor and generating an armature current command for rotationally driving the rotor 10, and the field current command and the armature current. And a three-phase inverter 2 that generates an alternating current for converting the direct current based on the command and supplying the converted current to the winding. In the bearingless motor 1, the rotational torque of the rotor 10 is generated by the armature current (q-axis current), and the support force in the z-axis direction of the rotor 10 is generated by the field current (d-axis current). Thus, active control and rotation control of the z-axis direction position of the rotor of the bearingless motor 1 are performed by one three-phase inverter 2.

In the controller 52, as a support force generation control of the rotor 10 in the z-axis direction, the comparator B1 uses the z-axis position command value z ^* and the detected displacement z in the axial direction of the rotor 10 of the bearingless motor 1 in the comparator B1. The deviation is calculated and PID control is performed by the PID control unit B2, and a d-axis current command value i _d ^* which is a field current command is created. Further, a rotational speed command ω ^* is commanded as rotational drive control of the rotor 10 of the bearingless motor 1.

The comparator B3 calculates the deviation between the d-axis current command value i _d ^* and the detected d-axis current value i _d , PI control is performed by the PI control unit B4, and the d-axis voltage command value V _d ^* is created. .

In the differentiator B5, the rotational speed detection value ω is created by differentiating the phase angle θ of the rotor 10 of the bearingless motor 1 detected by an angle sensor (not shown). The difference between the rotational speed command ω ^* and the rotational speed detected value ω is calculated in the comparator B6, and PI control is performed in the PI control unit B7, and the q-axis current command value i _q ^*, which is an armature current command, is created. The Then, the difference between the q-axis current command value i _q ^* and the q-axis current detection value i _q is calculated in the comparator B8, PI control is performed in the PI control unit B9, and the q-axis voltage command value V _q ^* is created. Is done.

The three-phase / two-phase conversion circuit B10 performs three-phase / two-phase conversion on the d-axis voltage command value V _d ^* and the q-axis voltage command value V _q ^* using the phase angle θ of the rotor 10 of the bearingless motor 1. uvw outputs voltage command values V _u ^* , V _v ^* and V _w ^* for each phase. A conversion formula from the dq coordinate system to the three-phase coordinate system is expressed by Formula 5.

The voltage command values V _u ^* , V _v ^*, and V _w ^{* for} each phase of uvw are input to the three-phase inverter 2, and the three-phase inverter 2 converts the DC voltage into an AC voltage that is the drive voltage of the bearingless motor 1 in accordance with this. Convert and output. The output AC voltage is applied to each of the three-phase windings of the bearingless motor, and three-phase currents i _u , _iv and i _w flow through the respective windings of the bearingless motor 1.

The u-phase current i _u and the w-phase current i _w flowing from the three-phase inverter 2 to the winding 12 of the bearingless motor 1 are detected by the current sensor 54 and fed back. The three-phase two-phase conversion circuit B11 is configured to three-phase the detected u-phase current i _u and w-phase current i _w and the v-phase current i _v calculated from the u-phase current i _u and the w-phase current i _w. Two-phase conversion is performed, and a d-axis current detection value i _d caused by the support force of the rotor in the Z-axis direction and a q-axis current detection value i _q caused by the rotor torque are output. Note that the conversion equation from the three-phase coordinate system to the dq coordinate system is expressed by the inverse conversion of Equation 5, and the description is omitted here.

  Next, generation of axial force of the rotor of the bearingless motor in the electric motor system according to the present invention will be described. FIG. 16 is an xz sectional view for explaining the principle of generation of the axial force of the electric motor in the electric motor system of FIG. Here, a case is considered in which a current flows in the direction shown in the winding 22U and the auxiliary winding 24U and the permanent magnet 11 is magnetized in the direction shown in the drawing.

  In the gap G <b> 1, the magnetic flux caused by the permanent magnet 11 that has come out of the auxiliary teeth 23-1 passes obliquely downward and enters the permanent magnet 11. In the gap G3 and inside, the magnetic flux emitted from the permanent magnet 11 passes obliquely upward and enters the teeth 21-1 or the auxiliary teeth 23-1. Further, when a current flows in the illustrated direction in the winding 22U and the auxiliary winding 24U, a magnetic flux is generated in the Z direction (the direction of the thin broken arrow in the figure). As a result, the magnetic flux generated by the permanent magnet 11 in the gaps G1 and G3 and the magnetic flux generated by the winding 22U and the auxiliary winding 24U are strengthened, and the magnetic flux is weakened in the gaps G2 and G4. Thereby, a force is generated in the positive direction of the Z axis with respect to the rotor 10. On the other hand, in the winding 22U and the auxiliary winding 24U, when a current flows in the direction opposite to the illustrated direction, the magnetic flux is weakened in the gaps G1 and G3, and the magnetic flux is strengthened in the gaps G2 and G4. A force is generated in the negative Z-axis direction with respect to the rotor 10.

Next, the principle of generation of the radial force of the rotor of the bearingless motor in the electric motor system according to the present invention will be described using the bearingless motor 1 having the structure shown in FIGS. 13 and 14 as an example. FIG. 17 is an xz sectional view for explaining the principle of generation of the radial force in the sixth embodiment of the present invention. As shown in FIG. 17, when the rotation axis of the rotor 1 is tilted, in order to generate a restoring torque for correcting this tilt, the radial direction of the upper and lower permanent magnet layers is opposite to each other. It is enough to generate mosquitoes. That is, in the example of FIG. 17, if the radial force is generated in the + x-axis direction in the upper permanent magnet layer and in the −x-axis direction in the lower permanent magnet layer, the inclination of the rotation axis of the rotor 10 is corrected. A restoring torque _Tθ can be generated.

The direction of the radial force and the rotation axis related to the restoring torque are orthogonal to each other. As shown in FIG. 17, the radial force generated in the upper permanent magnet layer is F _u , the radial force generated in the lower permanent magnet layer is F _l , and the upper or lower permanent magnet layer from the center of gravity of the rotor 10. If the length in the z-axis direction up to is l _s , the restoring torque T _θ is expressed by Equation 6.

The radial forces F _u and F _l are proportional to the winding current (zero phase current i ₀ ) in a region where no magnetic saturation occurs. If the proportionality coefficient is k _i0 , it is expressed by Equation 7.

By substituting Equation 7 into Equation 6, a restoring torque T _θ proportional to the zero-phase current i ₀ as shown in Equation 8 is obtained.

FIG. 18 is an xy sectional view illustrating the winding structure of the motor in the motor system of FIGS. 13 to 17 as viewed from the axial direction (+ z-axis direction) of the rotor, and (A) is the upper stage of the three layers. , (B) shows the middle of the three layers, and (C) shows the lower of the three layers. FIG. 18 shows an example of the configuration of the bearingless motor 1 in which the upper permanent magnet layer and the lower permanent magnet layer generate opposite radial forces, and the middle and lower permanent magnets 11 of the rotor 10 are shown. The magnetizing directions of the upper permanent magnet 11 are the same as those of the upper permanent magnet 11. Further, the 8-pole stator windings 22U ₁ , 22U ₂ , 22V ₁ , 22V ₂ , 22W ₁ and 22W ₂ have the same winding direction in the upper stage and the lower stage, and only the middle stage has a winding in the opposite direction. Line is given. Since the rotor 20 has 8 poles, it is necessary to generate a 6-pole or 10-pole stator magnetic flux according to Equation 1. As shown in FIG. 18A, when a positive zero-phase current i _{0 is} passed through the stator windings 22U ₂ , 22V ₂ and 22W ₂ , the excited stator windings 22U ₂ , 22V ₂ and 22W ₂ are A radially inward magnetic flux is generated in the gap between the wound tooth 21-1 and the rotor 10 facing it. A radially outward magnetic east flows into the teeth 21-1 that are not excited by the positive zero-phase current i ₀ . As a result, a hexapole magnetic field is formed in the gap. FIG. 18 shows a case where the rotation angle of the rotor 10 is 0 degree as an example, but in this case, a radial direction force F _{r in the} positive direction of the α axis is generated. FIG. 18B shows the middle stage, but by passing a positive zero-phase current i ₀ through the stator windings 22U ₂ , 22V ₂ and 22W ₂ as in the upper stage shown in FIG. 18A. A radial direction force F _{r in the} positive direction of the α axis is generated. FIG. 18C shows the lower stage, but since the magnetization direction of the lower permanent magnet 11 is opposite to the magnetization direction of the upper permanent magnet 11, the radial direction force F _{r in the} negative α-axis direction is Occur. When the radial direction force F _r generated at each stage is added, a restoring torque T _θ that corrects the inclination of the rotating shaft of the rotor 10 is obtained.

  Next, suppression of radial vibration of the rotor of the bearingless motor in the electric motor system according to the present invention will be described. As explained based on the first to sixth embodiments, according to the present invention, the midpoint of the voltage on the DC side of the inverter and the Y-connected three-phase winding provided in the stator winding are One of the neutral points is connected by connecting means, and a zero-phase current is passed through this connecting means to generate a magnetic flux in the stator winding, which is rotated by this magnetic flux and the magnetic flux generated by the permanent magnet. Generate a radial force on the child. In order to suppress the vibration in the radial direction of the rotor of the bearingless motor, a radial force generated by flowing a zero-phase current is used.

  That is, in the electric motor system according to the present invention, the radial direction that suppresses the radial vibration of the rotor by appropriately adjusting the zero-phase current flowing through the connecting means in accordance with the radial vibration from the central axis of the rotor. Generate power. For this reason, the electric motor system according to the present invention includes a sensor that detects vibration in the radial direction from the central axis of the rotor, and the controller suppresses the vibration of the rotor based on information on the vibration detected by the sensor. A zero-phase current command for controlling the three-phase inverter is generated so that a zero-phase current for generating a radial force flows through the connecting means. The sensor is provided in the vicinity of the rotation axis of the rotor, or in a portion where the vibration of the rotor can be detected, such as the stator surface, the stator slot or the stator yoke. Taking the sixth embodiment as an example, as shown in FIGS. 13 and 14, the displacement sensor 51 that detects the displacement of the rotor in the z direction is near the lower end of the shaft 14 that serves as the rotational axis z of the rotor 10. Is provided.

  Here, as an example, a case where vibration in the radial direction of the four-pole rotor in the electric motor system according to the first embodiment described with reference to FIGS. 1 and 2 is suppressed will be described. Similarly, in the embodiment, vibrations in the radial direction of the rotor can be suppressed. Further, in the case of a bearingless motor satisfying Equation 1, the number of rotor poles, the number of stator slots, and the number of laminated permanent magnet layers However, the vibration of the rotor in the radial direction can be similarly suppressed.

FIG. 19 is a diagram for explaining suppression of vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the first embodiment of the present invention. In FIG. 19, the horizontal axis indicates the rotation angle of the rotor 10. In the first embodiment of the present invention, the case where the permanent magnet 11 of the rotor 10 is located at the position shown in FIG. 2 is described as an example. However, the rotor 10 actually rotates around the rotation axis z. Therefore, as shown in FIG. 19A, the radial force Fr rotates in synchronization with the electrical angle of the bearingless motor 1. In FIG. 19B, F _x ⁺ indicates the radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 19C, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3.

Here, as shown in FIGS. 19D and 19E, for example, consider the case where the vibrations F _x and F _y having the waveform indicated by the alternate long and short dash line are generated. At this time, if it is possible to generate a rotor 10 against when vibration F _x and F _y command value radial force is generated as a phase opposite F _x ^* and F _y ^*, suppress vibration F _x and F _y It is possible. However, the radial forces F _x ⁺ , F _x ⁻ , F _y ⁺ and F _y ⁻ generated with respect to the rotor 10 regardless of the positive or negative zero-phase current flowing through the connecting means 3 are shown in FIG. Only those shown in FIG. 19B can be generated. For example, as shown in FIG. 19B, the radial forces F _y ⁺ and F _y generated on the rotor 10 even if a positive or negative zero-phase current is passed through the connecting means 3 when the rotation angle is 90 degrees. ^- it is 0. That is, it is not possible to directly generate a radial force that matches the command values F _x ^* and F _y ^* of the radial force. Therefore, in the present invention, the radial force command values F _x ^* and F _y ^* are generated by a combination of the fundamental component and the harmonic component of the radial force.

For example, it is assumed that the vibration in the radial direction of the rotor 10 changes in a sine wave shape with respect to the rotation angle. When the amplitude of the zero-phase current is I ₀ , the frequency of the zero-phase current is θ, and the phase of the zero-phase current is φ, the zero-phase current i ₀ can be expressed by Equation 9.

Coefficients force on zero-phase current k _i0, when the number of poles of the rotor 10 and p _r, the radial force F _x in the x-axis direction with respect to the rotor 10 is represented by the formula 10, y-axis direction with respect to the rotor 10 The radial force F _y is expressed by Equation 11.

As can be seen from Equations 10 and 11, the radial forces F _x and F _y on the rotor 10 depend on the frequency θ of the zero-phase current. In other words, if the fundamental wave component and the harmonic component of the zero-phase current are controlled, the fundamental wave component and the harmonic component of the radial force can be controlled, and as a result, the radial direction in the direction of suppressing the vibration of the rotor. It can be seen that force can be generated. Therefore, in the present invention, for example, a sensor provided in the vicinity of the rotation axis of the rotor 10 detects vibration in the radial direction from the central axis of the rotor 10, and based on the information related to the vibration, Command values (fundamental wave component and harmonic wave component) of zero phase current that generates radial force in the direction to suppress vibration are created.

FIG. 20 is a diagram illustrating generation of a command value for suppressing primary vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the first embodiment of the present invention. In FIG. 20, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 20A, F _x ⁺ indicates the radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 20B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 20C shows the zero-phase current i ₀ of the primary component (fundamental wave component) flowing through the connecting means 3. At this time, as shown in FIGS. 20D and 20E, the command values for the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. , The radial forces F _x and F _y indicated by the broken lines in FIGS. _20D and 20E can be generated on the rotor 10.

FIG. 21 is a diagram illustrating generation of a command value for suppressing the fourth-order vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the first embodiment of the present invention. In FIG. 21, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 21A, F _x ⁺ represents a radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 21B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 21C shows the zero-phase current i ₀ of the secondary component flowing through the connecting means 3. At this time, as shown in FIG. 21D and FIG. 21E, the command values for the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. , The radial forces F _x and F _y shown by the broken lines in FIGS. _21D and 21E can be generated on the rotor 10.

FIG. 22 is a diagram illustrating generation of a command value for suppressing primary vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the third embodiment of the present invention. In FIG. 22, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 22A, F _x ⁺ represents a radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 22B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 22C shows the zero-phase current i ₀ of the secondary component flowing through the connecting means 3. At this time, as shown in FIG. 22D and FIG. 22E, the command values for the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. , The radial forces F _x and F _y shown by the broken lines in FIGS. _22D and 22E can be generated on the rotor 10.

FIG. 23 is a diagram illustrating generation of a command value for suppressing secondary vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the third embodiment of the present invention. In FIG. 23, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 23A, F _x ⁺ represents a radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 23B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 23C shows the zero-phase current i ₀ of the primary component flowing through the connecting means 3. At this time, as shown in FIGS. 23D and 23E, the command values for the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current of FIG. , The radial forces F _x and F _y shown by the broken lines in FIGS. _23D and 23E can be generated on the rotor 10.

FIG. 24 is a diagram illustrating generation of a command value for suppressing primary vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the fourth embodiment of the present invention. In FIG. 24, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 24A, F _x ⁺ represents a radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 24B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 24C shows the zero-phase current i ₀ of the third-order component flowing through the connecting means 3. At this time, as shown in FIGS. 24D and 24E, the command values for the radial force in the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. , The radial forces F _x and F _y shown by the broken lines in FIGS. _24D and 24E can be generated on the rotor 10.

FIG. 25 is a diagram illustrating generation of a command value for suppressing secondary vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the fourth embodiment of the present invention. In FIG. 25, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 25A, F _x ⁺ indicates a radial force in the x-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _x ⁻ The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 25B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 25C shows the zero-phase current i ₀ of the secondary component flowing through the connecting means 3. At this time, as shown in FIG. 25 (D) and FIG. 25 (E), the command values of the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. 25 (C) , The radial forces F _x and F _y indicated by the broken lines in FIGS. _25D and 25E can be generated on the rotor 10.

FIG. 26 is a diagram illustrating generation of a command value for suppressing the sixth-order vibration in the radial direction of the rotor of the bearingless motor in the electric motor system according to the fourth embodiment of the present invention. In FIG. 26, the horizontal axis indicates the rotation angle of the rotor 10. In FIG. 26 (A), F _x ⁺ represents the radial force in the x-axis direction generated against the rotor 10 to that which causes a positive constant zero-phase current to the connection means 3, F _x ^- is The radial force in the x-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current flows through the connecting means 3 is shown. In FIG. 26B, F _y ⁺ indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a positive constant zero-phase current is passed through the connecting means 3, and F _y ⁻ Indicates a radial force in the y-axis direction generated with respect to the rotor 10 when a negative constant zero-phase current is passed through the connecting means 3. FIG. 26C shows the zero-phase current i ₀ of the secondary component flowing through the connecting means 3. At this time, as shown in FIGS. 26D and 26E, the command values for the radial force of the waveform shown by the solid line are F _x ^* and F _y ^*, and the zero-phase current in FIG. , The radial forces F _x and F _y indicated by the broken lines in FIGS. _26D and 26E can be generated on the rotor 10.

  In the above-described example, the method of generating the zero-phase current so as to generate the radial force having the opposite phase to the vibration of the rotor 10 detected by the sensor is shown. However, as an alternative example, the rotation detected by the sensor The zero-phase current may be generated so that a radial force whose phase is shifted with respect to the vibration of the child 10 is generated.

1 bearingless motor 2 three-phase inverter 3 connected means 10 rotor 11 permanent magnet 12 nonmagnetic material 20 stator 21 stator core 21-1 tooth 21-2,23-2 yoke 23-1 auxiliary teeth 22U _1, 22U ₂ windings 22V ₁ , 22V ₂ windings 22W ₁ , 22W ₂ windings 24U, 24V, 24W Auxiliary winding 30 Passive magnetic bearing 31 Rotor side permanent magnet 32 Stator side permanent magnet 51 Displacement sensor 52 Controller 54 Current sensor 100 Electric motor system

Claims (4)

A rotor in which permanent magnets are arranged so that a radially outward magnetic flux and a radially inward magnetic flux are alternately generated in the circumferential direction with respect to the rotation axis, and a gap in a radial direction with respect to the rotor A plurality of teeth that protrude toward the rotor side in the circumferential direction, and the stator windings of each phase of the multiphase windings connected to the neutral point are interposed between the teeth. An electric motor having a stator disposed respectively;
An inverter that converts an input direct current and generates an alternating current for supplying to the stator winding;
Connecting means for connecting the midpoint of the DC side voltage of the inverter and one of the neutral points of the multiphase winding;
A controller for controlling the inverter so that a zero-phase current flows through the connection means;
With
An electric motor system, wherein a radial force is generated on the rotor by a magnetic flux generated by flowing a zero-phase current through the connecting means and a magnetic flux generated by the permanent magnet. A sensor that detects vibration of the rotor in a radial direction from a central axis;
The controller is configured to control the inverter based on information about vibration detected by the sensor so that a zero-phase current that generates a radial force flows in the connection means in a direction to suppress vibration of the rotor. The electric motor system according to claim 1, wherein a zero-phase current command is generated. In each phase of the multiphase winding, the stator winding consists of a set of windings connected in parallel to each other,
The neutral point when one of the sets of windings connected in parallel for each phase is Y-connected is connected to the midpoint of the voltage on the DC side of the inverter by the connecting means,
Each set of windings generates a radial force in one direction on the rotor by a magnetic flux generated by a zero-phase current flowing through the neutral point and a magnetic flux generated by the permanent magnet. The electric motor system according to claim 1, wherein the electric motor system is disposed between the teeth. When the number of poles of the rotor is p _r and the number of poles of a magnetic field generated when a zero-phase current is passed through the stator winding is p _s ,
p _s = p _r ± 2
The electric motor system according to any one of claims 1 to 3, wherein the rotor and the stator satisfy the relational expression represented by:

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