JP2006352953A - Motor and its control method, compressor, blower, air conditioner and vehicle-mounted air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge the operation range within the voltage range of a drive source while attaining the downsizing and higher efficiency of a motor. <P>SOLUTION: A rotor 100 is provided with magnets 31-34 for fields arranged in a line in its circumferential direction. The relative positional relation, in its circumferential direction, with each circumferential center of the tooth 201 of an inner stator 200 and the tooth 301 of an outer stator 300 is variable. Magnetic flux Ψa is generated from the peripheral magnetic pole face (N pole) of the magnet 32, and until it returns to the inner peripheral face (S pole) of the magnet 32, a path via its wide part 202 exists without linking with an armature coil 203, at the tooth 201 of the inner stator 200. This path substantially weakens the field being given from the magnet 32 to the inner stator 200. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of an electric motor, and a motor control technique using the structure. The electric motor and control technology can be applied to a compressor and a blower.

  In realizing a small and highly efficient motor, a permanent magnet excitation motor using a permanent magnet is desirable. In addition, there is a recent social demand for reducing the environmental load, and there is a demand for a motor and a drive device that are not only highly efficient at a constant rotation but also highly efficient in operation at a high rotation.

  However, unlike an induction motor, a permanent magnet excitation motor generates a counter-inductive voltage proportional to the rotational speed. Therefore, in principle, the torque is insufficient at a low rotation and the rotation speed is insufficient at a high rotation within the limitation of the drive voltage. Therefore, in general, the number of windings of the coil is selected with the target of the rotational frequency at which the motor is frequently used, and a motor with a winding specification having a good overall efficiency within a certain period of time as the entire driving device is mounted.

  A technique for expanding the operating range while maintaining a small size and high efficiency has been proposed in spite of such a fundamental constraint. For example, in Patent Document 1, electromagnets are arranged at the upper and lower ends of the rotor, and the torque is increased by exciting the electromagnet in a direction in which the permanent magnet is magnetized during low-speed rotation (hereinafter referred to as “strong field”). A technique is disclosed in which an electromagnet is excited in a direction in which a permanent magnet is demagnetized (hereinafter referred to as “weak field”) in order to reduce a reverse induced voltage during high-speed rotation.

  Patent Document 2 discloses a technique that does not perform field-weakening control in a high-speed rotation region, but expands the operating range with only a strong field in a low-speed rotation region.

  In Patent Document 3, a rotor is divided into a radially outer rotor and a radially inner rotor, and field weakening control can be realized without energization by mechanically changing the relative position in the rotational direction. Is disclosed.

  Patent Document 4 discloses an electric motor that simplifies the mechanism for changing the relative position by employing a clutch mechanism.

  In Patent Document 5, a plug that has magnetic permeability anisotropy in the rolling direction of a grain-oriented electrical steel sheet and adjusts the magnetic resistance is used, and a field weakening current is not passed and a field weakening is continuously finely adjusted. Techniques to do this are disclosed.

Japanese Patent No. 3490330 JP 2004-260970 A JP 2002-58223 A JP 2004-320864 A Japanese Patent Laid-Open No. 9-233887 Japanese Patent Application No. 2005-53206

  However, in the electric motor disclosed in Patent Document 1, although it is possible to expand the operating range, the copper loss increases due to the current supplied to the electromagnet used for the strong field and the weak field, so that the operating efficiency decreases. To do.

  In the disclosed example of Patent Document 2, although an effect can be expected if the leakage magnetic flux of the permanent magnet can be controlled, no specific technique is disclosed for the control. Even if it is controllable, copper loss occurs due to the current flowing to the auxiliary stator coil. Therefore, compared with a normal permanent magnet excitation motor that uses the volume as the first permanent magnet without using the second permanent magnet. The driving efficiency at low speed is reduced.

  In Patent Document 3, as can be seen from FIG. 2 (of Patent Document 3) showing an example of the embodiment, the partial arc-shaped groove forms a hard-to-magnetize region, so that the magnetic resistance increases. This reduces the interlinkage magnetic flux of the permanent magnet, so that the operating efficiency in a region where no field weakening is performed is reduced as compared with a normal permanent magnet embedded motor. As is apparent from FIGS. 4 and 5 showing the modified embodiment, this modification does not have the groove portion of FIG. 2 mentioned earlier, but the inner rotor having four salient poles, which is half of the number of magnetic poles. Is used. The number of salient poles is not limited to 4, and a magnetic path can be formed only in half (180 degrees) with respect to the circumference (360 degrees) in principle. Therefore, even in this deformation, the operation efficiency in the region where the field weakening is not performed is lowered as compared with a normal permanent magnet embedded motor.

  Furthermore, as another modified embodiment, there is a disclosure of FIGS. As is apparent from these, an embedded magnet rotor is used for the inner rotor. If it is this aspect, unlike the above-mentioned aspect, the linkage flux of the permanent magnet in the area | region which does not perform field-weakening control will not fall. However, the usage amount or thickness of the permanent magnet is approximately doubled. Therefore, the operation efficiency in a region where no field weakening is performed is reduced as compared with a normal permanent magnet embedded electric motor when a permanent magnet having an equivalent thickness is used. Furthermore, even if this point is excluded, since the permanent magnets directly face each other during field weakening control, they are exposed to a strong demagnetizing field, and there is a risk of irreversible demagnetization.

  Even in the electric motor described in Patent Document 4, the same problem arises because the electric motor shape shown in FIGS.

  In Patent Document 5, as shown in FIG. 3, there is a problem that the width of anisotropy of magnetic permeability depends on the magnetic field strength. When the magnetic field strength is 1 [Oe] ≈79.6 [A / m], the magnetic permeability ratio is about 0.0025: 0.018, which can be seen as slightly less than 7 times. However, when the magnetic field strength is 3 [Oe] ≈238.8 [A / m], the permeability ratio is about 0.005: 0.007, which is 1.4 times, and 10 [Oe] ≈796 [A / m]. The permeability ratio at about 0.002: 0.0018 is about 1.1 times.

  Although the material of the stator body 7 of Patent Document 5 is not mentioned, even if a high-performance non-oriented electrical steel sheet is used for miniaturization, the magnetic field strength H = 1, 3, 10 [Oe] is the same as the previous one. Are about B = 0.7, 1.3, and 1.48 [T], respectively. That is, if the stator is used at an operating point of about 0.7 [T] in a large sized motor design, field weakening by the magnetoresistive adjustment plug is possible.

  However, when aiming to reduce the size and cost of an electric motor, it is not desirable to provide a margin for the magnetic flux density of the stator. Even if the magnetic flux density is estimated to be small and this is 1.3 [T], the permeability ratio can be obtained only about 1.4 times. The contribution to the magnetoresistance of the permanent magnet magnetomotive force is first the permanent magnet itself, then the air gap, and the ratio of the magnetoresistance of the stator yoke is small. Furthermore, since the magnetic path length of the yoke portion is longer than that of the magnetoresistive adjustment plug, the contribution of the magnetoresistive adjustment plug to the magnetic anisotropy is further reduced. Therefore, when the magnetic flux density is designed to be high, the width for adjusting the field weakening in the stator is small.

  The present invention has been made in view of the above circumstances, and aims to expand the operating range within the drive power supply voltage range while further aiming to reduce the size and increase the efficiency of the motor, or to further reduce the vibration of the motor. The purpose is to do.

  A first aspect of the electric motor according to the present invention is a rotor (100) having a substantially cylindrical shape including an outer peripheral surface (100a) and an inner peripheral surface (100b), and having field magnets (31 to 34). The armature winding (203) has teeth (201, 202) wound around the inner peripheral side stator (200) provided on the inner peripheral surface side, and the armature winding (303). Is provided with an outer peripheral side stator (300) provided on the outer peripheral surface side. The relative positional relationship between the circumferential center of the tooth portion of the inner circumferential stator and the circumferential center of the tooth portion of the outer stator is variable.

  A second aspect of the electric motor according to the present invention is the first aspect of the electric motor, wherein the armature winding (203) of the inner peripheral side stator (200) and the outer peripheral side stator (300) are provided. The armature winding (303) is connected in series for each phase.

  A third aspect of the electric motor according to the present invention is the first aspect or the second aspect of the electric motor, wherein the field magnets (31 to 34) are formed of the outer peripheral surface (100a) and the inner peripheral surface (100b). ).

  A fourth aspect of the electric motor according to the present invention is any one of the first to third aspects of the electric motor, and includes the rotor (100), the inner peripheral side stator (200), and the outer peripheral side fixed. The relative position of the child (300) is variable along the axial direction of the cylindrical shape.

  A fifth aspect of the electric motor according to the present invention is any one of the first to fourth aspects of the electric motor, and includes the rotor (100), the inner peripheral side stator (200), and the outer peripheral side fixed. The child (300) is relatively eccentrically fixed along a direction perpendicular to the cylindrical axial direction.

  A sixth aspect of the electric motor according to the present invention is any one of the first to fourth aspects of the electric motor, wherein the rotor (100), the inner peripheral side stator (200), and the outer peripheral side fixed The relative position of the child (300) is variable along a direction perpendicular to the axial direction of the cylindrical shape.

  The electric motor according to the present invention can be applied to a compressor and a blower, and the compressor and the blower can be applied to an air conditioner.

  In addition, the electric motor according to the present invention can finely adjust the rotational speed without depending on the number of windings, and is therefore suitable for a compressor of an in-vehicle air conditioner that operates at a low voltage such as 42 V or less. .

  A first aspect of the motor control method according to the present invention is a method for controlling the operation of the first to fourth aspects of the motor, and includes at least the inner peripheral side stator (200) and the outer peripheral side. For one of the stators (300), the phase of the armature current flowing through the armature winding is set to an advance angle.

  A second aspect of the motor control method according to the present invention is a method for controlling the operation of the fourth aspect of the motor, wherein the rotor (100), the inner peripheral side stator (200), and the motor The relative positional relationship with the outer circumferential side stator (300) along the axial direction of the cylindrical shape is set.

  A third aspect of the motor control method according to the present invention is a method for controlling the operation of the sixth aspect of the motor, wherein the rotor (100), the inner peripheral side stator (200), and the motor A relative positional relationship with the outer circumferential side stator (300) is set along a direction perpendicular to the axial direction of the cylindrical shape.

  In the first aspect of the electric motor according to the present invention, the field applied from the field magnet to the teeth of the inner stator and the field applied from the field magnet to the teeth of the outer stator The phase difference between and becomes variable. Therefore, the field weakening can be equivalently realized without controlling the armature current supplied to the armature windings of the inner and outer stators. Therefore, an increase in copper loss due to the weak magnetic flux current and a demagnetization of the field magnet due to the negative d-axis current do not occur. In addition, since the relative positional relationship between the inner and outer stators can be set independently of the phase of the armature current with respect to the d-axis of the field magnet, the torque can also be controlled separately. .

  In the second aspect of the electric motor according to the present invention, even if the induced voltage becomes unbalanced, the annular current does not flow, and the loss can be reduced.

  In the third aspect of the electric motor according to the present invention, not only magnet torque but also reluctance torque can be used.

  In the fourth aspect of the electric motor according to the present invention and the second aspect of the electric motor control method according to the present invention, the area where the rotor, the inner peripheral side stator and the outer peripheral side stator face each other decreases. More mechanical field weakening control can be obtained. Moreover, since an axial suction force is generated between the two, vibration in the axial direction can also be suppressed.

  In the fifth aspect of the electric motor according to the present invention, a translation force that is stabilized to some extent is generated between the rotor, the inner peripheral side stator, and the outer peripheral side stator in a direction perpendicular to the axial direction. And can suppress vibration in the direction perpendicular to.

  In the sixth aspect of the electric motor according to the present invention and the third aspect of the electric motor control method according to the present invention, the amount of eccentricity is measured by measuring the imbalance in the induced voltage and current waveform induced in the armature winding. Can be adjusted.

  In the first aspect of the motor control method according to the present invention, the same control as that of a normal field weakening is performed independently of the relative positional relationship between the inner peripheral side stator and the outer peripheral side stator. Therefore, the operation efficiency in the high speed rotation region can be improved.

First embodiment.
FIG. 1 illustrates a configuration of an electric motor according to a first embodiment of the present invention, and is a cross-sectional view perpendicular to the rotation axis direction. The rotor 100 includes an outer peripheral surface 100a and an inner peripheral surface 100b, and an inner peripheral stator 200 is provided on the inner peripheral surface 100b side, and an outer peripheral stator 300 is provided on the outer peripheral surface 100a side. By providing the stator inside and outside the rotor 100, the total cross-sectional area of the winding slot can be increased.

  FIG. 2 is a cross-sectional view illustrating the configuration of the rotor 100 and perpendicular to the rotation axis direction. Both the outer peripheral surface 100a and the inner peripheral surface 1 have an annular shape. Here, both are concentric circles, but they are not necessarily perfect circles, and design changes can be made as appropriate. For example, for the purpose of reducing the harmonics of the induced voltage, it may be partially eccentric and may have an uneven shape.

  The rotor 100 is provided with field magnets 31 to 34 arranged in the circumferential direction. The field magnets 31 to 34 alternately present different magnetic pole surfaces on the outer peripheral surface 100a side and the inner peripheral surface 100b side, respectively. That is, here, a case where a permanent magnet rotor having two pole pairs is employed as the rotor 100 is illustrated.

  Here, a so-called embedded magnet type rotor is illustrated as the rotor 100. In other words, the field magnets 31 to 34 are located between the outer peripheral surface 100a and the inner peripheral surface 100b. In such an embedded magnet type rotor, not only magnet torque but also reluctance torque can be used.

  In order for the magnetic flux obtained from the field magnets 31 to 34 to be effectively applied as a field to the inner peripheral side stator 200 and the outer peripheral side stator 300, the magnetic flux does not short-circuit inside the rotor 100. It is desirable. For this purpose, air gaps 21 and 22 are provided at both ends of the field magnet 31, air gaps 23 and 24 are provided at both ends of the field magnet 32, and air gaps 25 and 26 are provided at both ends of the field magnet 33. Air gaps 27 and 28 are provided at both ends of the field magnet 34, respectively. Filling the gaps 21 to 28 with a nonmagnetic material is desirable from the viewpoint of improving the mechanical strength of the rotor 100.

  The air gaps 21 to 28 divide the rotor 100 into first portions 11 to 14 through which not only the d-axis magnetic flux but also the q-axis magnetic flux pass, and the second portions 15 to 18 through which the q-axis magnetic flux mainly passes. Field magnets 31 to 34 exist in the first portions 11 to 14 together with the core of the rotor 100, respectively, and the core of the rotor 100 exists in the second portions 15 to 18. Here, for the sake of convenience, among the first portions 11 to 14, the cores on the outer peripheral surface 100 a side of the field magnets 31 to 34 are the outer peripheral cores 11 a to 14 a, and the core on the inner peripheral surface 100 b side is the inner peripheral core 11 b to. 14b.

  Returning to FIG. 1, the case where the field magnets 31 and 33 present the south pole magnetic pole surface and the field magnets 32 and 34 the north pole magnetic pole surface, respectively, faces the outer stator 300. Has been. The outer peripheral side stator 300 has a tooth portion 301 extending in the radial direction, and the tip (rotor 100 side) is widened in the circumferential direction to form a wide portion 302. Similarly, the inner peripheral side stator 200 has a tooth portion 201 extending in the radial direction, and the tip (rotor 100 side) extends in the circumferential direction to form a wide portion 202. Armature windings 203 and 303 are wound around the tooth portions 201 and 301, respectively.

  The magnetic flux flows in and out of the rotor 100 and the outer stator 300 mainly through the tooth portion 301, and the magnetic flux flows in and out of the rotor 100 and the inner stator 200 mainly through the tooth portion 201. . In FIG. 1, the magnetic fluxes Ψa and Ψb by the field magnets 31 to 34 are illustrated using arrows.

  FIG. 3 is a diagram conceptually showing how the d-axis magnetic flux φc flows through the rotor 100, and FIG. 4 is a diagram conceptually showing how the q-axis magnetic flux φa, φb flows through the rotor 100. This corresponds to the cross-sectional view of FIG.

  The d-axis magnetic flux φc flows between the field magnets 31 and 33 and the field magnets 32 and 34. Therefore, the d-axis magnetic flux φc flows only through the first portions 11 to 14.

  The q-axis magnetic flux φa flows through the first portions 11 to 14, more specifically, the outer cores 11a, 12a, 13a, and 14a. However, the q-axis magnetic flux φb also flows through the second portions 15-18. Therefore, expanding the circumferential width W (see FIG. 2) of the second portions 15 to 18 is desirable from the viewpoint of increasing the reluctance torque by increasing the q-axis inductance Lq.

  The inner peripheral side stator 200 is an armature around which the armature winding 203 is wound, and it is desirable that this is not a rotor. If the inner armature of the rotor 100 is a rotor, a mechanical commutator is required and the outer armature 300, which is an outer armature, rotates relative to the outer armature. This relative rotation reduces the relative rotational speed of any armature with respect to the field of the rotor 100, leading to a reduction in the efficiency of the motor. In addition, this relative rotation disturbs the path of the q-axis magnetic flux φb, increases the fluctuation of the reluctance torque, and makes its use difficult.

  FIG. 5 is an enlarged cross-sectional view partially showing the space between the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300. 5, tooth portions 201U and 301U are tooth portions 201 and 301 of the inner peripheral side stator 200 and the outer peripheral side stator 300, respectively, and armature windings 203 and 303 through which a U-phase current flows are wound. . FIG. 5 illustrates a case where the centers of the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300 all coincide with the center Q. However, as described later, such coincidence of the centers is not always necessary.

  In the present invention, the relative positional relationship between the circumferential center of the tooth portion 201U of the inner circumferential side stator 200 and the circumferential center of the tooth portion 301U of the outer circumferential side stator is variable. In FIG. The case where it has shifted | deviated only (alpha) is illustrated. More specifically, with reference to the circumferential position of the center of the tooth portion 301U of the outer stator 300, the center of the tooth 201U of the inner stator 200 is counterclockwise as a positive direction by an angle α. The angle α is variably set including positive and negative.

  Such a variable angle α can be set mechanically before or during use of the electric motor. For example, the displacement may be caused manually before using the electric motor, or the displacement may be caused by an actuator such as a servo motor during use.

  Note that the angle θ is the rotation angle of the rotor 100 with respect to the outer stator 300 of the rotor 100, and the center of the field magnet 32 (or field magnet 34) exhibiting the N pole is the outer periphery. The angle is shifted in the positive direction from the center of the tooth portion 301U of the side stator 300.

  Returning to FIG. 1, the magnetic flux Ψa indicates the magnetic flux generated from the magnetic pole surface (N pole) on the outer peripheral side of the magnet 32, and the magnetic flux Ψb indicates the magnetic flux generated from the magnetic pole surface (S pole) on the outer peripheral side of the magnet 33. Yes. As shown in FIG. 1 and FIG. 5, there is a positional shift of the angle α. Therefore, when the magnetic flux Ψa returns to the magnetic pole surface on the inner peripheral side of the magnet 32, the tooth portion 301 is moved to the yoke of the outer peripheral side stator 300. In the tooth portion 201 of the inner circumference side stator 200, there is a path that passes through the wide portion 202 without interlinking with the armature winding 203. . Similarly, when the magnetic flux Ψb returns to the magnetic pole surface on the inner peripheral side of the magnet 33, it interlinks with the armature winding 203 via the teeth 201 of the inner peripheral stator 200, but the outer peripheral stator 300. In the tooth portion 301, there is a path through the wide portion 302 without interlinking with the armature winding 303.

  These paths substantially weaken the field applied from the magnets 32 and 33 to the inner peripheral side stator 200 and the outer peripheral side stator 300, respectively. That is, the above-described positional deviation mechanically realizes the weakening magnetic flux control that is the substantial field weakening control. In this manner, the flux weakening control can be realized without flowing the flux weakening current, and the efficiency improvement in the high output region can be achieved. FIG. 1 shows a positional shift corresponding to 30 degrees as a mechanical angle and 60 degrees as an electrical angle.

  According to this embodiment, there is no increase in copper loss due to the weak magnetic flux current, or irreversible demagnetization of the field magnet due to the negative d-axis current. In addition, the relative positional relationship between the inner peripheral side stator 200 and the outer peripheral side stator 300 can be set independently of the phase of the armature current with respect to the d-axis of the field magnets 31 to 34. Therefore, the torque can be controlled separately while reducing the copper loss, the field weakening is adopted within the range of the drive power supply voltage, the operation efficiency in the high speed rotation region is improved, and the operation range due to the high rotation speed Contribute to the expansion of

  As to which of the outer peripheral side stator 300 and the inner peripheral side stator 200 advances the armature current phase angle, the rotation angle θ is set in the same direction as the rotation direction of the rotor 100 or in the opposite direction. Can be switched.

  In particular, if an embedded magnet type rotor is employed as the rotor 100, the method of holding the field magnets 31 to 34 on the rotor 100 is also simple, which contributes to cost reduction. Further, since the reluctance torque can also be used, the torque is high even if the phase of the armature current is set to the advance side, and the operation range in the high-speed rotation region can be easily expanded.

  Further, by providing both the inner peripheral side stator 200 and the outer peripheral side stator 300 with respect to the rotor 100, the total cross-sectional area of the winding slot can be increased, and the torque and efficiency in the low speed rotation region can be improved. it can.

  As described above, it is preferable to perform the flux weakening control by adjusting the mutual positional relationship between the inner and outer armatures, particularly when the motor is downsized. As described above, Patent Document 5 uses the magnetic permeability anisotropy in the rolling direction of the grain-oriented electrical steel sheet to embed an adjustment plug in the stator. However, this impairs the magnetic flux density of the stator itself.

  In addition, since the magnetic flux density of the wide part 202,302 of a tooth part raises in the case of weakening magnetic flux control, the iron loss in the wide part 202,302 rises. However, since the magnetic flux density passing through the tooth portions 202, 302 other than the wide portions 202, 302 is reduced, the iron loss in the longer magnetic path can be reduced, so that the total iron loss of the motor is reduced.

  In addition, the electric motor according to the present embodiment is suitable for the case where the electric motor is used to operate at a low pressure because it is easy to finely adjust the rotational speed even when the same current is used. In an electric motor that operates at a low pressure, the number of winding turns is small, so it is not easy to make fine adjustments by changing the number of windings. This is because the change in the number of windings is a discrete numerical control.

  FIG. 6 is a cross-sectional view of an electric motor including the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300, and conceptually shows a cross section including the rotation center. The rotor 100 is connected to a rotating shaft 103 via an end plate 102, and the rotating shaft 103 is supported by bearings 104 and 105. The inner peripheral side stator 200 and the outer peripheral side stator 300 are supported by support portions 204 and 304, respectively. Armature windings 203 and 303 are wound around the inner peripheral side stator 200 and the outer peripheral side stator 300, respectively. 1 corresponds to a cross-sectional view in which the support portions 204 and 304 and the armature windings 203 and 303 are omitted at a position II in FIG.

  7 and 8 are circuit diagrams illustrating an aspect in which the armature windings 203 and 303 (see FIG. 1) are connected. The coils 203U, 203V, and 203W shown in FIGS. 7 and 8 are the U-phase, V-phase, and W-phase coils of the armature winding 203, respectively. The coils 303U, 303V, and 303W are the armature windings, respectively. Reference numeral 303 denotes a U-phase, V-phase, and W-phase coil.

  7 and 8 show a case where the armature windings 203 and 303 are connected in series and in parallel in each phase. In the present embodiment, any of such serial connection and parallel connection can be employed.

  7 and 8 show a case where the star connection is adopted and the armature windings 203 and 303 are connected in series and in parallel in each phase. In the present embodiment, any of such serial connection and parallel connection can be employed. Of course, as shown in FIGS. 9 and 10, delta connection may be adopted, and the armature windings 203 and 303 may be connected in series and in parallel in each phase. However, if the delta connection is adopted, the annular current due to the imbalance of the induced voltage increases the copper loss. Therefore, it is desirable that the armature windings 203 and 303 are connected in series for each phase by using the star connection. .

  Even if any of the connection methods shown in FIGS. 7 to 10 is used, the above-described electric motor can be driven by a single inverter. Therefore, when armature currents are individually supplied to the armature windings 203 and 303, respectively. In view of the need for two inverters, the cost is low.

  Moreover, the positional relationship at the same time with respect to the d-axis of the rotor 100 of the inner peripheral side stator 200 and the outer peripheral side stator 300 is different. Therefore, although the armature current is output from one inverter with one common phase shift for each phase, the current phase is changed between the inner and outer stators 200 and 300 for the motor. It is possible to supply a rotating magnetic field with almost any difference. That is, it is easy to control the field weakening control and the torque control almost individually.

  The electric motor according to the present embodiment is also suitable for a compressor of an in-vehicle air conditioner that operates at a low voltage such as 42 V or less. When the required cooling capacity varies depending on the application model, the number of turns of the winding is extremely small in an electric motor that operates at a low voltage such as 42V. Since the number of windings can be changed only by a discrete value, it is difficult to adjust the maximum rotational speed, the maximum torque, etc. by changing this.

  On the other hand, in the electric motor according to the present embodiment, it is easy to adjust the maximum rotational speed and the maximum torque by adjusting the relationship between the operating condition and the angle α indicating the deviation between the inner and outer stators. Therefore, it is possible to cope with other models by changing only the control of the angle α.

  Of course, the electric motor according to the present invention can be mounted on the compressor or blower of a normal air conditioner to improve the efficiency of compression or blowing. Therefore, the air conditioner provided with at least one of the compressor and the blower can increase the air conditioning efficiency.

  There are also social demands for improving the heat insulation of houses and responding to low environmental loads, and operating hours in low load areas are increasing. On the other hand, there is also a demand to increase the maximum number of revolutions in order to ensure the ability to start up cooling rapidly. Thus, the electric motor and its control method according to the present invention are suitable for the requirement that the efficiency is high at a low load and the maximum rotation speed is large.

  Now, the fact that the flux-weakening control can be performed by adjusting the mutual positional relationship between the inner and outer armatures will be described from the viewpoint of the phasor of the magnetic flux and voltage. The magnetic fluxes serving as fields applied from the rotor 100 to the inner peripheral side stator 200 and the outer peripheral side stator 300 are denoted by φi and φo, respectively. Further, the d-axis direction of the rotor 100 with respect to the inner peripheral side stator 200 is referred to as a di-axis, and the d-axis direction of the rotor 100 with respect to the outer peripheral side stator 300 is referred to as a do-axis.

  FIG. 11 is a diagram showing the phasors of the magnetic fluxes φi and φo when the deviation angle α of the inner peripheral side stator 200 with respect to the outer peripheral side stator 300 is 0 degree. Since the angle α is 0 degree, the di axis and the do axis coincide. Therefore, the magnitude of the magnetic flux φa, which is a field when viewed as the whole electric motor, is the sum of the magnitudes of the magnetic fluxes φi and φo.

  On the other hand, FIG. 12 is a diagram showing the phasors of the magnetic fluxes φi and φo when the deviation angle α is positive. In this case, since the do axis is shifted from the di axis by an angle P · α (P is the number of pole pairs of the rotor 100), the magnitude of the magnetic flux φa is smaller than the sum of the magnitudes of the magnetic fluxes φi and φo. Become. Therefore, the field when viewed as the whole electric motor is weakened.

  More specifically, since the armature current flows in any of the motors of the inner peripheral side stator 200 and the outer peripheral side stator 300, not only the magnetic fluxes φi and φo but also the armature current, the d-axis inductance, and the q-axis inductance. The virtual flux considered is taken as the magnetic flux of the field as the whole motor.

  FIGS. 13 and 14 are diagrams showing phasors of magnetic flux when the armature current is taken into account, and show cases where the angle α is 0 and positive, respectively. In each figure, two broken lines indicate vector translation. The virtual magnetic flux Φa viewed from the whole electric motor is shorter in the direction shown in FIG. 14 than in the direction shown in FIG. 13.

  Of the inductances obtained by the inner peripheral side stator 200 and the rotor 100, the di-axis component is d-axis inductance Ldi, and the component whose phase is orthogonal to this is the q-axis inductance Lqi. Similarly, of the inductances obtained by the outer stator 300 and the rotor 100, the do-axis component is d-axis inductance Ldo and the component whose phase is orthogonal to this is the q-axis inductance Lqo. Further, the di-axis component of the armature current of the inner peripheral side stator 200 is the current Idi, the component whose phase is orthogonal to the current Iqi, and the do-axis component of the armature current of the outer peripheral side stator 300 is the current Ido, The component whose phase is orthogonal to this is defined as current Iqo.

  However, since the magnetic flux flows between the inner peripheral side stator 200 and the outer peripheral side stator 300 via the rotor 100, the calculation of the d-axis inductance Ldi and the q-axis inductance Lqi is mutually influenced by the influence of the outer peripheral side stator 300. In consideration of the inductance, it is desirable to consider the mutual inductance due to the influence of the inner peripheral side stator 200 when calculating the d-axis inductance Ldo and the q-axis inductance Lqo.

  Thus, even when the armature current is taken into consideration, it can be seen that the virtual magnetic flux Φa can be reduced by the shift of the angle α. Since the virtual magnetic flux Φa is a value obtained by dividing the voltage generated in the motor by the time differential ω of the rotation angle θ of the rotor and the pole pair number P, the motor is given to this by reducing it. High speed operation can be performed under the restriction of the voltage of the drive power supply.

  Furthermore, it is also possible to obtain a field weakening separately by shifting the phase β of the armature current while shifting the position of the inner and outer armatures. For example, the current phase βi of the armature current flowing through the inner peripheral side stator 200 is set to 10 degrees, and the current phase βo of the armature current flowing through the outer peripheral side stator 300 is set to 70 degrees. When it is desired to perform field weakening, the product Pα of the angle α and the number P of pole pairs may be selected to be 60 degrees. In this way, while the current obtained from one current supply circuit is commonly used as the armature current that flows through the inner peripheral side stator 200 and the outer peripheral side stator 300, the normal current is used in both current phases. Weak field can be performed.

  The relationship between the mechanical position control of the inner and outer stators and the armature current phase β when performing field-weakening control, which is an effect of the present invention, has been described above. The following supplements the maximum torque control or the maximum efficiency control when there is a margin in the upper limit of the voltage of the drive power supply.

  A current phase that realizes the maximum generated torque or maximum efficiency between the outer peripheral side stator 300 and the rotor 100 and between the inner peripheral side stator 200 and the rotor 100 (hereinafter, in any case). (Denoted as “optimal current phase”).

  It is conceivable that the optimal current phase for the armature current of the outer peripheral side stator 300 and the optimal current phase for the armature current of the inner peripheral side stator 200 are substantially equal. This is the case when there is no significant magnetic saturation and the ampere turns input to each armature winding are equal. This is realized, for example, when the number of turns of the armature winding is the same between the outer peripheral side stator 300 and the inner peripheral side stator 200, and these armature windings are connected in series with each other. it can.

  On the other hand, if the ampere turns input to the respective armatures are different, the generation ratio of the magnet torque and the reluctance torque is different between the outer peripheral side stator 300 and the inner peripheral side stator 200, so the two optimum current phases are different. .

  The value obtained by subtracting the optimum current phase for the outer stator 300 from the optimum current phase for the inner stator 200 is δ, and the positional deviation of the inner stator 200 with respect to the outer stator 300 is defined as δ. The angle α to be shown is selected as δ / P (P is the number of pole pairs described above). And if the operation adopting two optimum current phases for each stator is performed, it can be applied to a high torque region or a load region where high efficiency is required (for example, a rated load region that is operated for a long time). I can deal with it.

  If the two optimum current phases are equal, both δ and α are zero, the centers of the tooth portions 201 and 301 in the circumferential direction are matched, and the operation is performed with the same optimum current phase.

  In the operation region in which operation at high speed is preferentially required over the above-described maximum efficiency operation, | α |> | δ / P |. The above-described field weakening control may be performed in which the expansion of the operation range is given priority over the efficiency, and one stator is operated so as to weaken the field of the rotor 100.

  In this case, since the current phase β of any stator does not become the optimum current phase, the operation efficiency is lowered as compared with the maximum efficiency operation. However, mechanical field-weakening control operation is superior in terms of expanding the operating range (number of revolutions or generated torque) when compared with normal field-weakening field control with only field-weakening current. ing. On the other hand, if the operation is compared in an equivalent output, it can be said that the field-weakening current can be lowered, which is excellent in terms of operation efficiency.

Second embodiment.
FIG. 15: is sectional drawing which shows the structure of the electric motor concerning the 2nd Embodiment of this invention, and has shown notionally the cross section containing a rotation center. The configuration described with reference to FIG. 6 in the first embodiment is that the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300 are along the cylindrical axial direction of the rotor 100. And the relative positional relationship is variable. FIG. 15 illustrates that the rotor 100, the end plate 102, and the rotating shaft 103 are shifted in a direction from the bearing 104 toward the bearing 105.

  In the electric motor having such a configuration, an area where the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300 face each other is reduced. Thereby, mechanical field-weakening control can be further obtained. Moreover, since an axial suction force is generated between the two, vibration in the axial direction can also be suppressed.

  The suppression of the vibration suppresses the vibration in the rotation axis direction of the refrigerant compressor for the air conditioner, for example, using the electric motor. On the other hand, it is also useful when a recording medium such as a DVD (Digital Versatile Disk) that is rotated and read / written (or one of them) is rotated. When applied to the latter, it is possible to reduce read (or write) errors by reducing the vertical vibration of the DVD.

  If the relative position in the rotation axis direction is excessively shifted in order to generate the axial attractive force, the magnetic flux of the field may be reduced and the operation efficiency may be reduced. Take care. However, it is also possible to perform control that is variable according to the operation state such as the load state, and it is possible to improve the overall operation efficiency and reduce the vibration.

Third embodiment.
FIG. 16: is sectional drawing which shows the structure of the electric motor concerning the 3rd Embodiment of this invention, and has shown notionally the cross section perpendicular | vertical to a rotation center. The configuration described with reference to FIG. 1 in the first embodiment is that the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300 are in a direction perpendicular to the axial direction of the rotor 100. Along with this, the relative positional relationship is variable. In FIG. 16, the center Q2 of the rotor 100 and the center Q1 common to the inner peripheral side stator 200 and the outer peripheral side stator 300 are shown. Such a relative position may be decentered and fixed, or may be variable.

  In the case of being fixed eccentrically, a translation force that is stable to some extent is generated between the rotor 100, the inner peripheral side stator 200, and the outer peripheral side stator 300 in a direction perpendicular to the axial direction. Vibration in a direction perpendicular to the direction can be suppressed. For example, the electric motor is used to suppress vibration in the direction perpendicular to the rotation axis direction of the refrigerant compressor. Even when a DVD is driven, vibration in the disk plane direction can be reduced, and reading (or writing) errors can be reduced.

  When a sintered oil-impregnated bearing or the like is used for the bearings 104 and 105 of the rotating shaft 103 of the electric motor, lubrication is performed by a wedge effect due to oil existing between the outer diameter of the rotating shaft 103 and the inner diameter of the bearings 104 and 105. Ensuring a stable amount of eccentricity with respect to the inner diameter of the bearings 104 and 105 is very important for reducing the wear of the bearings 104 and 105, and the life of the bearings 104 and 105 is a leading factor for determining the life of the general-purpose motor. Therefore, the above-described vibration suppression is also useful from the viewpoint of extending the life of a motor, and in turn, a product that employs the motor.

  When the relative positional relationship is variable, the eccentricity can be adjusted by measuring an imbalance in the induced voltage or current waveform induced in the armature winding. In general, when performing so-called “centering” in which the center of the rotor and stator is aligned in an electric motor, it is common to assemble with increased mechanical accuracy in actual industrial production. There is no guarantee that it can be done. Therefore, for example, the outer diameters of the bearings 104 and 105 of the rotating shaft 103 are made elliptical, and the bearings 104 and 105 are rotated so that the rotation between the rotor 100 and the inner and outer stators 200 and 300 is performed. It is preferable to change the relative position in the direction perpendicular to the rotation axis direction. That is, after assembling the electric motor, it is possible to adjust the eccentricity by measuring the induced voltage and current waveform imbalance induced in the armature windings 203 and 303 to perform centering. Depending on the bearings 104 and 105 and the type of load variation, the vibration can be reduced by centering.

It is sectional drawing which shows the structure of the electric motor concerning the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the rotor concerning the 1st Embodiment of this invention. It is a figure which shows notionally a mode that d-axis magnetic flux flows into a rotor. It is a figure which shows notionally a mode that q-axis magnetic flux flows into a rotor. It is a top view which shows the positional relationship of the rotor and stator concerning the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the electric motor concerning the 1st Embodiment of this invention. It is a circuit diagram which shows the aspect by which an armature winding is connected in the 1st Embodiment of this invention. It is a circuit diagram which shows the aspect by which an armature winding is connected in the 1st Embodiment of this invention. It is a circuit diagram which shows the aspect by which an armature winding is connected in the 1st Embodiment of this invention. It is a circuit diagram which shows the aspect by which an armature winding is connected in the 1st Embodiment of this invention. It is a figure which shows the phasor in the 1st Embodiment of this invention. It is a figure which shows the phasor in the 1st Embodiment of this invention. It is a figure which shows the phasor in the 1st Embodiment of this invention. It is a figure which shows the phasor in the 1st Embodiment of this invention. It is a top view which shows the structure of the magnetic body concerning the 2nd Embodiment of this invention. It is a top view which shows the structure of the magnetic body concerning the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Rotor 200 Inner peripheral side stator 201, 301 Tooth part 203, 303 Armature winding 300 Outer peripheral side stator

Claims (13)

A rotor (100) having a substantially cylindrical shape including an outer peripheral surface (100a) and an inner peripheral surface (100b) and having field magnets (31 to 34);
An inner peripheral side stator (200) provided on the inner peripheral surface side, having tooth portions (201, 202) around which an armature winding (203) is wound;
An armature winding (303) having teeth (301, 302) wound thereon, and an outer peripheral side stator (300) provided on the outer peripheral surface side;
An electric motor in which a relative positional relationship between a circumferential center of the tooth portion of the inner circumferential side stator and a circumferential center of the tooth portion of the outer circumferential side stator is variable.   The armature winding (203) of the inner peripheral side stator (200) and the armature winding (303) of the outer peripheral side stator (300) are connected in series for each phase. The electric motor according to claim 1.   The electric motor according to claim 1, wherein the field magnets (31 to 34) are located between the outer peripheral surface (100 a) and the inner peripheral surface (100 b).   The relative positional relationship between the rotor (100), the inner circumferential side stator (200), and the outer circumferential side stator (300) is variable along the axial direction of the cylindrical shape. The electric motor according to any one of claims 1 to 3.   The rotor (100), the inner peripheral side stator (200), and the outer peripheral side stator (300) are relatively eccentrically fixed along a direction perpendicular to the axial direction of the cylindrical shape. The electric motor according to any one of claims 1 to 4, wherein:   The relative positional relationship between the rotor (100), the inner peripheral side stator (200), and the outer peripheral side stator (300) is variable along a direction perpendicular to the axial direction of the cylindrical shape. The electric motor according to claim 1, wherein the electric motor is provided.   The compressor which employ | adopted the electric motor as described in any one of Claims 1 thru | or 6.   A blower employing the electric motor according to any one of claims 1 to 6.   An air conditioner comprising at least one of the compressor according to claim 7 and the blower according to claim 8.   An in-vehicle air conditioner comprising a compressor on which the electric motor according to any one of claims 1 to 6 is mounted. A method for controlling the operation of the electric motor according to any one of claims 1 to 6,
The motor control method, wherein at least one of the inner peripheral side stator (200) and the outer peripheral side stator (300) is set to advance the phase of the armature current flowing through the armature winding. A method for controlling the operation of the electric motor according to claim 4, comprising:
Control of an electric motor that sets a relative positional relationship between the rotor (100), the inner peripheral side stator (200), and the outer peripheral side stator (300) along the axial direction of the cylindrical shape. Method. A method for controlling the operation of the electric motor according to claim 6, comprising:
A relative positional relationship between the rotor (100), the inner peripheral side stator (200), and the outer peripheral side stator (300) along a direction perpendicular to the axial direction of the cylindrical shape is set. , Control method of electric motor.

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