JP6231285B2 - Permanent magnet synchronous machine and compressor using the same - Google Patents

Description

  The present invention relates to a permanent magnet synchronous machine and a drive system using the same.

  In the permanent magnet synchronous machine, an interior permanent magnet (hereinafter, IPM) structure in which a permanent magnet is embedded in a rotor is widely adopted. In the IPM structure, since the ratio of the direct-axis inductance Ld and the horizontal-axis inductance Lq, the so-called salient pole ratio, is increased, it has been said that reluctance torque can be used in addition to magnet torque.

  As a background art of a permanent magnet synchronous machine utilizing reluctance torque, there is a synchronous machine described in Japanese Patent Application Laid-Open No. 2001-119875 (Patent Document 1). In this publication, the rotor 100 has a structure in which a magnetic salient pole type rotor part 102 and a magnet type rotor part 101 are coupled in series in the axial direction, and the magnetic salient pole type magnetic pole of the magnetic salient pole type rotor part 102 is provided. The magnetic flux and the magnetic flux of the magnet-type rotor part 101 permanent magnet type field pole are linked to a common multilayer armature coil. By configuring in this way, the relative angle of both rotor parts is set optimally compared to a synchronous machine that generates a combined torque of reluctance torque by magnetic salient pole type field poles and magnet torque by permanent magnet type field poles. This increases the combined torque per permanent magnet amount.

Japanese Patent Laid-Open No. 2001-11985

  In the synchronous machine of Patent Document 1, the salient pole ratio is increased by using an IPM structure, and reluctance torque is utilized. However, depending on the application, output, and motor size, there is an IPM structure, that is, it is difficult to utilize the reluctance torque even if the salient pole ratio is increased. This is because the magnitude of the reluctance torque depends not only on the magnitude of the salient pole ratio but also on the relative relationship with the magnet torque. However, this viewpoint has been overlooked in the conventional design theory. For this reason, reluctance torque cannot be used and output and efficiency cannot be improved. On the other hand, because the salient pole ratio is large, inductance increases and iron loss increases or speeding up may be difficult. .

  An object of the present invention is to enable torque improvement and efficiency improvement in a permanent magnet synchronous machine even when it is difficult to utilize reluctance torque.

  In order to achieve the above object, in the present invention, the rotor has a plurality of magnetic poles having a shape projecting radially inward, and the interlinkage magnetic flux Ψp ( WB) and the permanent magnet synchronization in which the direct-axis inductance Ld (H) and the horizontal-axis inductance Lq (H) when the current effective value Irms (Arms) is supplied to the stator coil satisfy the relationship of the expression (1) The magnetic saturation of the stator core is alleviated by disposing a slit made of a non-magnetic material on the outer periphery of the permanent magnet in the radial direction to reduce the horizontal axis inductance Lq.

  According to the present invention, torque and efficiency are improved.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The figure which shows a stator and a rotor by the cross section perpendicular | vertical to a rotating shaft about the permanent magnet synchronous machine in 1st Example of this invention. The figure which shows the relationship of (1) Formula which concerns on this invention. The figure which shows a rotor by the cross section perpendicular | vertical to a rotating shaft about the permanent magnet synchronous machine in 1st Example of this invention. Explanatory drawing of the torque characteristic in 1st Example of this invention. An example of the motor characteristic in the 1st example of the present invention. The cross-section figure of the compressor in the 2nd Example of this invention. The fragmentary sectional view which shows a rotor with the longitudinal cross-section in alignment with a rotating shaft about the permanent magnet synchronous machine in the 3rd Example of this invention. About the permanent magnet synchronous machine in the 3rd Example of this invention, the fragmentary sectional view which shows a rotor in the cross section perpendicular | vertical to a rotating shaft (VIB-VIB cross section of FIG. 6A). FIG. 6 is a partial cross-sectional view showing a rotor in a cross section perpendicular to a rotation axis of a permanent magnet synchronous machine according to a third embodiment of the present invention (VIC-VIC cross section in FIG. 6A). The fragmentary sectional view which shows a rotor by the cross section perpendicular | vertical to a rotating shaft about the permanent magnet synchronous machine in the 4th Example of this invention. The stator coil connection diagram of a 6 pole 9 slot three phase motor. The principle explanatory drawing of magnet torque and reluctance torque. Permanent magnet motor vector illustration. The fragmentary sectional view which shows the rotor of the permanent magnet synchronous machine which is a comparative example with this invention with a cross section perpendicular | vertical to a rotating shaft.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same symbols are attached to the same components. Their names and functions are the same, and duplicate descriptions are avoided. Further, in the following description, the inner rotor is targeted, but the effect of the present invention is not limited to the inner rotor, and can be applied to an outer rotor having a similar configuration. is there. Further, the winding method of the stator may be concentrated winding or distributed winding. Further, the number of rotor poles and the number of phases of the stator coils are not limited to the configuration of the embodiment. In the following description, an inverter-driven permanent magnet motor is targeted. However, the effect of the present invention can also be applied to a self-starting permanent magnet motor.

  The first embodiment of the present invention will be described below with reference to FIGS. In the description of the present embodiment, FIGS. 9 to 12 are referred to. FIG. 1 is a diagram showing a stator and a rotor in a cross section perpendicular to a rotation axis in a permanent magnet synchronous machine according to a first embodiment of the present invention. FIG. 2 is a diagram showing the relationship of the expression (1) according to the present invention. FIG. 3 is a view showing the rotor in a cross section perpendicular to the rotation axis of the permanent magnet synchronous machine in the first embodiment of the present invention. FIG. 4 is an explanatory diagram of torque characteristics in the first embodiment of the present invention. FIG. 5 is an example of motor characteristics in the first embodiment of the present invention. FIG. 9 is a stator coil connection diagram of a 6-pole 9-slot three-phase motor. FIG. 10 is an explanatory diagram of the principles of magnet torque and reluctance torque. FIG. 11 is a vector diagram of a permanent magnet motor. FIG. 12 is a partial cross-sectional view showing a rotor of a permanent magnet synchronous machine, which is a comparative example with the present invention, in a cross section perpendicular to the rotation axis.

The permanent magnet synchronous machine of a present Example is demonstrated using FIG.
In the permanent magnet synchronous machine of the present embodiment, the rotor 1 is provided on the inner peripheral side of the stator 9. The rotor 1 is rotatably held by a bearing (not shown) via a gap G with respect to the stator 9. The stator 9 includes a stator core 10 and a stator winding 12 wound around a tooth 11. The stator winding 12 arranges three-phase windings U, V, and W in the circumferential direction in order. In each of the U phase, V phase, and W phase, three coils are connected in series (FIG. 9). A total of nine coils 12u1, 12u2, 12u3, 12v1, 12v2, 12v3, 12w1, 12w2, and 12w3 are separately wound around each tooth 11 to constitute a concentrated permanent magnet synchronous machine. For this purpose, the stator 9 is provided with teeth 11 and nine slots. The rotor 1 is composed of a rotor core 2 having a permanent magnet housing hole 4 and permanent magnets 3 arranged to form 6 poles (number of pole pairs p = 3). A through hole 6a through which a shaft (rotating shaft, output shaft) 6 passes is formed at the center of the rotor 1, and the shaft 6 is inserted through the through hole 6a.

  As shown in FIG. 3, the permanent magnet synchronous machine of the present embodiment has a magnet housing hole 4 configured so that the rotor 1 protrudes radially inward, and the permanent magnet 3 is placed in the magnet housing hole 4. Buried. The permanent magnet 3 is inserted into the magnet accommodation hole 4, and a plurality of permanent magnets 3 and magnet accommodation holes 4 are provided along the circumferential direction, thereby forming a plurality of poles 30 along the circumferential direction inside the rotor 1. Is done. A linear-axis inductance Ld (H) and a horizontal-axis inductance Lq (when the stator coil is energized with the interlinkage magnetic flux Ψp (Wb) for one phase of the stator coil by the permanent magnet 3 and the phase current effective value Irms (Arms). H) has the relationship of the following formula (1).

  In the rotor 1, a slit 7 made of a non-magnetic material is disposed on the radially outer peripheral portion (outer peripheral side) of the permanent magnet 3.

  Here, first, the generation principle of the physical quantity and the reluctance torque will be described with reference to FIG. 3, FIG. 9, and FIG. In this embodiment, a 6-pole 9-slot three-phase motor will be described. However, a 4-pole 6-slot or other three-phase motor having another pole number and number of slots may be used.

  For example, as shown in FIG. 9, an alternating current iu having a peak value I (the effective value at this time is Irms) is supplied from the inverter to the U-phase windings 12u1, 12u2, and 12u3 connected in series. The same applies to the V-phase windings 12v1, 12v2, 12v3 and the W-phase windings 12w1, 12w2, 12w3, but the current phase of each phase is shifted by 120 ° in electrical angle. The size of I or Irms can be obtained by using a device such as a wattmeter. Or it can obtain | require by acquiring a current waveform with an oscilloscope etc. and performing a Fourier analysis.

  The shaft 6 mechanically coupled to the rotor 1 is connected to a load, and by appropriately selecting the magnitude and phase of the current I, a rotational torque Me that balances the load is generated. The interlinkage magnetic flux Ψp for one phase of the stator coil drives the rotor 1 externally with the terminals Tu, Tv, and Tw of U, V, and W shown in FIG. 9 open, and the phase voltage peak value E0, Alternatively, it can be obtained by measuring the line voltage peak value E0 × √3. Specifically, the angular frequency ω [rad / s] when externally driven at a rotational speed N [rpm] per minute is obtained from the equation (2) and obtained by substituting it into the equation (3).

ω = 2π × N / 60 × p (p: number of pole pairs) (2)
Ψp = E0 / ω (3)
Incidentally, the torque Me of the magnet motor is generally generated by attraction / repulsion between the rotating magnetic field generated by the energizing currents of the stator windings U, V, and W and the rotor magnetic poles. In the case of a magnet motor, the rotor magnetic pole often refers to a magnetic field formed by a magnet, but when considering reluctance torque, the magnetic field formed by magnetizing the rotor core due to the influence of the rotating magnetic field is also the magnetic pole. It is easy to understand when considered as a kind of. In addition, since the electric current and magnetic flux at the time of synchronous operation of a magnet motor are alternating current amounts, the method of converting into a dq axis coordinate system (rotating coordinate system) and handling as a direct current amount is common. In general, in the dq-axis coordinate system, the magnetic pole central axis of the rotor is the d-axis, and the axis advanced 90 ° counterclockwise with respect to the d-axis, that is, the central axis between permanent magnets having different polarities is the q-axis. To do. In this case, it is possible to consider various physical quantities such as torque based only on the relative positional relationship between the dq axis and the rotating magnetic field regardless of the rotor position.

  The principle of torque generation of the magnet motor will be described with reference to FIG. In the figure, the counterclockwise direction is the positive direction. (A) shows magnet torque. (B) shows the reluctance torque generated when the d-axis current is negative, and is due to the magnetization of the rotor q-axis. (C) shows the reluctance torque generated when the d-axis current is negative, and is due to the magnetization of the rotor d-axis. As shown in (a), the magnet torque is torque generated by attraction and repulsion between the magnetic flux generated on the d-axis and the magnetic field formed by the q-axis current. At this time, a radial repulsive force is generated between the magnet magnetic flux and the d-axis current magnetic field, but no rotational force is generated. On the other hand, as shown in (b), when the rotor q-axis is magnetized by the q-axis current magnetic field, an attractive force and a repulsive force are generated between the magnetization of the rotor q-axis and the d-axis current magnetic field. This is a reluctance torque, and when the d-axis current is negative, that is, a positive torque is obtained during field-weakening operation, and a negative torque is obtained during a magnetizing action. Similarly, when the rotor d-axis is easily magnetized as shown in (c), a reluctance torque is generated in relation to the q-axis current magnetic field, which is a negative torque and a magnetizing action during field-weakening operation. Sometimes the torque is positive (generally, the sum of (b) and (c) is called reluctance torque).

  The magnet torque is proportional to the amount of magnetic flux generated by the magnet if the q-axis current is constant. That is, in order to increase the magnet torque, it is necessary to increase the amount of magnets or use a strong magnet, resulting in an increase in cost. On the other hand, since the reluctance torque is proportional to the difference between the q-axis and d-axis inductances, it has been considered that the torque can be increased by configuring the rotor magnetic circuit so that the difference between the two is large. It was.

  Now, among the constituent physical quantities of the formula (1), Ψp and Irms are obtained in the above-described manner, whereas the method for obtaining Ld and Lq is a rotor stationary method such as the Dalton-Cameron method or the like. There is a method of calculating backward from a vector diagram as described below.

  The current, voltage, and magnetic flux during synchronous operation of the magnet motor will be described using the vector diagram of the dq axis coordinate system of FIG.

  Taking the phase of the interlinkage flux Ψp for one phase of the stator coil by the permanent magnet as a reference, this is regarded as the d-axis, and the induced electromotive force E0, which is the time derivative of Ψp, is generated on the q-axis whose phase is advanced by 90 °. When the phase voltage V applied to the motor and the phase current I applied to the motor have a phase difference of θ and β with respect to E0, V and I are as shown in equations (4) and (5). It can be decomposed into a d-axis component and a q-axis component.

  The resistance R in FIG. 11 can be measured by using a resistance measuring instrument such as a Wheatstone bridge. Further, the voltage phase difference angle θ and the current phase difference angle β can be obtained by acquiring the waveforms of E0, V, and I and determining the phase relationship of each fundamental wave component. Although FIG. 11 shows the case of using the phase voltage and phase current waveforms, for example, even when the line voltage is obtained instead of the phase voltage, the phase difference between the phase voltage and the line voltage should be considered. Thus, θ and β can be obtained in the same manner.

  Using the physical quantities obtained above, Ld and Lq can be obtained from the voltage equation of Equation (6).

  The physical quantity of the formula (1) and the generation principle of the reluctance torque have been described above.

  Next, the basic principle of the present invention, that is, the principle that satisfies the relationship of the expression (1) and can arrange the slit 7a in the radially outer peripheral portion of the permanent magnet 3 to improve the torque and the efficiency. Will be explained.

  In general, the generated torque Me is expressed by the following equation using the number of pole pairs p, the interlinkage magnetic flux Ψp for one phase of the stator coil by a permanent magnet, the direct current Id, and the horizontal current Iq.

  However, Id, Iq, and Ψp are peak values.

  In Expression (7), the first term in {} represents the magnet torque, and the second term represents the reluctance torque. As is apparent from this equation, the reluctance torque is proportional to Lq−Ld, Id, and Iq, respectively. For this reason, conventionally, the salient pole ratio Lq / Ld or Lq-Ld has been used as an index of the magnitude of the reluctance torque. However, how much the reluctance torque contributes to the generated torque Me is determined by a relative relationship with the magnet torque. For example, when the reluctance torque is extremely small relative to the magnet torque, even if the reluctance torque slightly fluctuates (increases / decreases), the generated torque Me is hardly affected. Therefore, in addition to the conventional salient pole ratio, another physical quantity that can take into account the relative relationship with the magnet torque needs to be newly introduced into the index representing the magnitude of the reluctance torque.

  Here, the magnet torque becomes maximum when the current phase difference angle β = 0, and the maximum value Mp, max can be expressed by the following equation from equations (5) and (7).

  On the other hand, the reluctance torque becomes maximum when β = π / 4 (electric angle is 45 deg.), And the maximum values Mr and max can be expressed by the following equations from equations (5) and (7).

  Since the ratio of the equations (8) and (9) is nothing but an index representing the magnitude of the reluctance torque, this ratio is defined as the reluctance torque ratio α. When using the current peak I,

When the effective current value Irms is used,

It becomes. In the present invention, Expression (11) using the current effective value Irms is used.

  As is apparent from the equation (11), it is understood that Ψp and Irms are newly introduced as an index representing the magnitude of the reluctance torque in addition to the conventional Ld and Lq. Of these, Ψp is determined by the physical properties and shape of the permanent magnet, the stator winding specifications, and the motor cross-sectional shape, and can be obtained from a general induced electromotive force measurement test. Similarly, Ld and Lq are also determined by the motor configuration and energization current Irms, and can be obtained by a general motor inductance measurement method. Therefore, Ψp, Ld, and Lq are constants determined for each motor, and Equation (11) can be treated as a linear function of α and Irms.

  The reluctance torque ratio α can take an arbitrary value by changing the right side of the equation (11), in particular, the current value. From the viewpoint of improving the generated torque and improving the efficiency, the reluctance torque ratio α is as shown in FIG. Β = 45 deg. At which the torque Mr becomes maximum. It is desirable that the generated torque Me be equal to or greater than the magnet torque maximum value Mp, max. More specifically, the permanent magnet synchronous machine is driven in the range where the current phase difference angle is 0 to 45 ° when the efficiency maximization control is performed. The generated torque Me has a minimum value when the current phase difference angle is 0 ° and 45 °. Therefore, when the current phase difference angle is 0 ° and 45 °, the reluctance torque can be utilized by making the generated torque Me equal to or greater than the magnet torque maximum value Mp, max. That is,

The relationship should be established. When formula (12) is arranged,

Further, when the equation (11) is further transformed, the following equation is obtained.

  From the above, it is necessary to introduce Ψp and Irms in addition to the conventional Ld and Lq as an index representing the magnitude of the reluctance torque, and the relational expression (14) is satisfied in order to effectively use the reluctance torque. Showed that there is a need to do.

  However, when Expression (14) is not satisfied, that is, when the relationship of Expression (1) is satisfied, it is difficult to use the reluctance torque. In such a situation, the IPM structure as shown in FIG. 12 cannot improve the output and the efficiency, but the q-axis inductance is large due to the large salient pole ratio, leading to an increase in iron loss or high speed. Becomes difficult.

  Therefore, by arranging a slit 7a made of a non-magnetic material as shown in FIG. 3, q-axis inductance is reduced and magnetic saturation of the stator core is alleviated. As a result, as shown in FIG. 5, it is possible to drive to higher speed rotation, and at the same time, it is possible to improve torque and improve efficiency.

  By the way, when the above-described permanent magnet synchronous machine is driven, the current phase difference angle β can be arbitrarily set by the configuration of the control software. However, in the configuration satisfying the expression (1), the control that generates the maximum torque is performed. The operating point is 0 deg. ≦ β ≦ 22.5 deg. Exists in the range. Therefore, the torque and the efficiency can be improved more reliably by controlling the phase so as to be the above-mentioned phase.

Note that the permanent magnet 3 may be integrally formed without being divided in the circumferential direction per pole, or a plurality of permanent magnets 3 may be arranged in the circumferential direction. In the present embodiment, the magnet housing hole 4 has a cross-sectional shape perpendicular to the center of the rotation axis and a central portion 4c formed in a substantially straight line close to the shaft 6 and from both ends of the central portion 4c toward the outer peripheral side. It is formed in a bathtub shape having sleeve portions 4a and 4b formed in a substantially straight line (see FIG. 3). The permanent magnet 3 housed in the magnet housing hole 4 also has a central portion 3c and sleeve portions 3a, 3b formed in a substantially linear shape from both ends of the central portion 3c toward the outer peripheral side in accordance with the shape of the magnet housing hole 4. More specifically, the magnet housing hole 4 and the permanent magnet 3 constituting one pole have two bending points B1 and B2 that are arranged apart from each other in the circumferential direction. Furthermore, the magnet housing hole 4 and the permanent magnet 3 have two straight portions 4a (3a) and 4b (3b) extending from the respective bending points B1 and B2 toward the radially outer peripheral side. The two straight line portions 4a (3a) and 4b (3b) pass through the center of the magnetic pole so that the distance between the two straight line portions 4a (3a) and 4b (3b) increases toward the radially outer side. It is inclined with respect to 30cl. Three or more bending points may be provided. In this case, the two straight portions 4a (3a) and 4b (3b) are provided with the bending points B1 and B2 positioned at both ends in the circumferential direction as starting ends.

  Moreover, the permanent magnet 3 and the magnet accommodation hole 4 which comprise 1 pole are not necessarily limited to one. For example, the permanent magnet 3 constituting one pole is divided, and the permanent magnets 3 (3a, 3b) are respectively inserted into the straight portions (sleeves) 4a, 4b of the magnet housing hole 4, and the central portion 4c is a space. You can also. The magnet housing hole 4 may also be divided into straight portions (sleeve portions) 4a and 4b.

  Further, the permanent magnet 3 and the magnet housing hole 4 may be divided into a plurality in the direction of the rotation axis, or may be formed integrally without being divided. In addition to the shape having two bending points as shown in FIG. 2, the shape of the magnet constituting one pole may be a shape having three or more bending points, a U shape, or a V shape. But it ’s okay. The rotor core 2 may be composed of laminated steel plates stacked in the axial direction, may be composed of a dust core, or may be composed of amorphous metal.

  The slit 7a may be arranged so as not to prevent the transmission of the magnet magnetic flux and at the same time to prevent the transmission of the q-axis magnetic flux, and may be provided in a straight line shape or an arc shape. Moreover, you may comprise by a continuation and may divide | segment by a rib etc. and may comprise. Further, in FIG. 3, four wires are arranged per one pole, but any number may be used as long as it can be manufactured. The width of each slit 7a may be uniform or non-uniform.

  As described above, the slit 7a does not prevent transmission of the magnet magnetic flux but prevents transmission of the q-axis magnetic flux. For this reason, the slit 7a is provided so as to cross the q-axis magnetic flux with respect to the magnet magnetic flux and the q-axis magnetic flux generated on the outer peripheral side of the permanent magnet 3 of the rotor core 2 in a state where the slit 7a is not provided, It is provided so as to follow the magnet flux without crossing the magnet flux as much as possible. When the slit 7a is provided so as to meet this condition, the slit 7a is long (large in dimension) in the direction crossing the q-axis magnetic flux (direction along the magnetic flux), and in the direction crossing the magnetic magnetic flux (direction along the q-axis magnetic flux). The shape is short (small size or thin width).

  The slit 7a will be further described in detail. In this embodiment, as shown in FIG. 3, the d-axis passes through the rotation center (center of the shaft 6) O of the rotor 1 and the center 4 o of the magnet housing hole 4. The permanent magnet 3 is inserted so as to fill the magnet accommodation hole 4 while leaving a gap 4 s at both ends of the magnet accommodation hole 4 so as to be line symmetric with respect to the d-axis. The permanent magnet 3 may be inserted so as to completely fill the magnet accommodation hole 4 without leaving the gap 4s. In this embodiment, since the d-axis passes through the center 30c of the magnetic pole, the d-axis is hereinafter referred to as a magnetic pole center line 30cl.

  The slit 7a is inclined with respect to the magnetic pole center line 30cl so as to approach the magnetic pole center line 30cl on the outer peripheral side and away from the magnetic pole center line 30cl on the inner peripheral side. That is, the slit 7a is formed to be inclined with respect to the magnetic pole center line 30cl so that the outer peripheral side end is closer to the magnetic pole center line 30cl with respect to the inner peripheral side end. Specifically, the length of the perpendicular line (distance between the outer peripheral side end 7ao and the magnetic pole center line 30cl) d7ao from the outer peripheral side end 7ao of the center line 7acl of the slit 7a to the magnetic pole center line 30cl is equal to the slit 7a. The length of the perpendicular line (the distance between the outer peripheral side end 7ai and the magnetic pole center line 30cl) d7ai from the inner peripheral side end 7ai of the center line 7ac1 to the magnetic pole center line 30cl is shorter than the slit 7a. Inclined with respect to the line 30cl.

  The slit 7a is formed on at least one side of the magnetic pole center line 30cl in one magnetic pole. In the present embodiment, slits 7a are formed on both sides of the magnetic pole center line 30cl. The slits 7a formed on both sides of the magnetic pole center line 30cl are formed symmetrically with respect to the magnetic pole center line 30cl. By forming the slits 7a symmetrically with respect to the magnetic pole center line 30cl, the design regarding the permeability between the magnet magnetic flux and the q-axis magnetic flux becomes easy. However, the slits 7a are not necessarily formed symmetrically with respect to the magnetic pole center line 30cl.

  In FIG. 3, the slit 7a is formed in an arc shape so as to have the above-described inclination, but may be formed in a linear shape. When the slit 7a is formed in an arc shape, a convex curve may be drawn toward the magnetic pole center line 30cl along the magnetic flux.

  Next, the slit 7b shown in FIG. 3 will be described. Even if the slit 7b is not provided, the effect of the slit 7a can be obtained, and therefore the slit 7b is not necessarily provided. However, the effect described below is obtained by providing the slit 7b.

  The slit 7b is provided in the radially inner peripheral part (inner peripheral side) of the permanent magnet 3, and is made of a nonmagnetic material in the same manner as the slit 7a.

  By adopting such a configuration, the effect of reducing the q-axis inductance is further enhanced, and the magnetic saturation of the stator core can be further alleviated. As a result, the permanent magnet synchronous machine can be further rotated at a high speed, and at the same time, further torque improvement and efficiency improvement can be achieved.

  The slit 7b may be arranged so as not to prevent the transmission of the magnet magnetic flux and at the same time prevent the transmission of the q-axis magnetic flux, and may be provided in a straight line shape or an arc shape. Moreover, you may comprise by a continuation and may divide | segment by a rib etc. and may comprise. Further, any number may be used as long as it can be manufactured. Further, the width of each slit may be uniform or non-uniform.

  Next, the permanent magnet 3 will be described. As the permanent magnet 3, a neodymium magnet can be used. However, according to the configuration of the present embodiment, even if the permanent magnet 3 is formed of a ferrite magnet, it is possible to compensate for a decrease in torque and a decrease in efficiency, and to generate a large magnet torque. Hereinafter, these configurations and effects will be described.

  The residual magnetic flux density (Br) of a ferrite magnet at room temperature (20 ° C.) is known to be 1/3 that of a neodymium magnet, but the temperature coefficient of Br of a ferrite magnet is more than twice that of a neodymium magnet. As the temperature increases, the decrease in Br, that is, the decrease in magnet torque becomes more significant. Specifically, the temperature coefficient of neodymium magnets is about -0.11% / K, while the ferrite magnet is about -0.26% / K. Therefore, the Br ratio with respect to the neodymium magnet decreases as the ambient temperature increases. In particular, when the ambient temperature is 80 ° C. or higher, the tendency of Br to decrease becomes significant. In such a case, by applying the present invention, it is possible to compensate for torque reduction and efficiency reduction due to Br reduction.

  Further, when the permanent magnet 3 is composed of a ferrite magnet, as shown in FIGS. 3 and 6, there are two bending points per pole in the circumferential direction, and the respective bending points are used as starting points with respect to the magnetization direction. Thus, it is effective to configure it to extend vertically and toward the end of the pole.

  By adopting such a magnet shape, the surface area of the magnet magnetic flux generating surface can be increased, so that it is possible to generate a larger magnet torque than that using a U-shaped ferrite magnet. In addition, you may comprise the permanent magnet 3 so that it may have a several bending point and linear part of three or more places.

  In addition, since the weight of a rotor core outer peripheral part reduces by adding a slit, the centrifugal force which acts on the said part falls. For this reason, even when it is difficult to increase the speed due to restrictions on the rotor strength, the configuration of the present invention enables driving at higher speed.

  Hereinafter, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a sectional structural view of the compressor according to the present embodiment.

  In FIG. 6, the compression mechanism unit meshes a spiral wrap 15 standing upright on the end plate 14 of the fixed scroll member 13 and a spiral wrap 18 standing upright on the end plate 17 of the turning scroll member 16. Is formed. The revolving scroll member 16 is revolved by the crankshaft 6 to perform the compression operation. Of the compression chambers 19 (19a, 19b,...) Formed by the fixed scroll member 13 and the swivel scroll member 16, the compression chamber 19 located on the outermost diameter side is accompanied by a swirl motion. The scroll members 13 and 16 move toward the center, and the volume gradually decreases.

  When both the compression chambers 19 a and 19 b reach the vicinity of the centers of the scroll members 13 and 16, the compressed gas in both the compression chambers 19 is discharged from the discharge port 20 communicating with the compression chamber 19. The discharged compressed gas passes through the gas passage (not shown) provided in the fixed scroll member 13 and the frame 21 and reaches the pressure vessel 22 below the frame 21, and the side wall of the pressure vessel 22. Is discharged from the discharge pipe 23 provided outside the compressor. A permanent magnet motor 103 composed of the stator 9 and the rotor 1 is enclosed in the pressure vessel 22, and the compression operation is performed by the rotation of the rotor 1. An oil sump 25 is provided below the permanent magnet motor 103. The oil in the oil sump 25 passes through an oil hole 26 provided in the crankshaft 6 due to a pressure difference caused by a rotational motion, and a sliding portion between the turning scroll member 16 and the crankshaft 6 and a sliding bearing 27. It is used for lubrication. A terminal box 30 for pulling out the stator coil 12 to the outside of the pressure vessel 22 is provided on the side wall of the pressure vessel 22. For example, in the case of a three-phase permanent magnet motor, terminals of U, V, and W windings are provided. There are a total of three. By applying the permanent magnet synchronous machine described in the above-described first embodiment, later-described third or fourth embodiment to the permanent magnet motor 103, it is possible to drive to a higher speed, and at the same time improve the torque. In addition, the efficiency can be improved.

  By the way, in many current home and commercial air conditioners, the R410A refrigerant is sealed in the compression container 22, and the ambient temperature of the permanent magnet motor 103 is often 80 ° C. or more. In the future, as the adoption of R32 refrigerant having a smaller global warming potential progresses, the ambient temperature further increases, so that the reduction in Br of the magnet becomes more prominent. In such a case, by applying the permanent magnet synchronous machine described in the first embodiment and the third or fourth embodiment described later, it is possible to compensate for a torque decrease and efficiency decrease due to a decrease in Br. In particular, when the permanent magnet 3 is composed of a ferrite magnet, high temperature demagnetization which is a problem with a neodymium magnet does not occur in principle, which is an effective measure against an increase in ambient temperature due to the adoption of the R32 refrigerant. In addition, when applying the permanent magnet synchronous machine of Example 1 mentioned above and Example 3 or Example 4 mentioned later to the compressor of a present Example, the kind of refrigerant | coolant is not restrict | limited.

  The compressor configuration may be the scroll compressor shown in FIG. 6, a rotary compressor, or a configuration having other compression mechanisms. Further, according to the present invention, as described above, a small and high output motor can be realized. Then, it becomes possible to widen the operating range, such as enabling high-speed operation. Further, in refrigerants such as He and R32, leakage from gaps is larger than refrigerants such as R22, R407C, and R410A, and in particular, low speeds. During operation, the ratio of leakage to the circulation amount is significantly increased, so that the efficiency is greatly reduced. Reducing leakage loss by reducing the size of the compression mechanism and increasing the rotational speed to obtain the same amount of circulation can be an effective means to improve efficiency during low circulation (low speed operation). It is necessary to increase the maximum number of revolutions in order to secure the circulation rate. According to the compressor provided with the permanent magnet synchronous machine according to the present invention, the maximum torque can be increased, so that the maximum number of rotations can be increased, which is effective for improving the efficiency of refrigerants such as He and R32. It becomes a means.

  Hereinafter, a third embodiment of the present invention will be described with reference to FIGS. 7a, 7b and 7c. FIG. 7A is a partial cross-sectional view showing a rotor in a longitudinal section along a rotation axis in a permanent magnet synchronous machine according to a third embodiment of the present invention. FIG. 7B is a partial cross-sectional view (a VIB-VIB cross section in FIG. 7A) showing the rotor in a cross section perpendicular to the rotation axis in the permanent magnet synchronous machine in the third embodiment of the present invention. FIG. 7C is a partial cross-sectional view (VIC-VIC cross section of FIG. 6A) showing the rotor in a cross section perpendicular to the rotation axis in the permanent magnet synchronous machine in the third embodiment of the present invention. 7B and 7C, the permanent magnet 3 is not shown, but the permanent magnet 3 is provided in the magnet accommodation hole 4 as in the first embodiment.

  The configuration of this embodiment is different from that of FIG. 3 in that the slits 7a are not periodically arranged in the circumferential direction but are arranged in an unbalanced manner.

  Specifically, a thin plate-like rotor core member 2 a having an output shaft through-hole 6 a through which the shaft (output shaft) 6 passes, a magnet housing hole 4, and a slit 7 a is laminated in the axial direction of the shaft 6. 1 is arranged and slits 7a are arranged so that a part of the laminated rotor core members 2a does not coincide with the center of gravity of the rotor core member 2a and the center of gravity of the shaft 6 inserted in the rotor core. Thus, the rotor core member 2a having a biased center of gravity is obtained.

  More specifically, the slit 7a is not provided for one pole. Alternatively, the number of slits 7a may be changed. In short, it is only necessary that the center of gravity position of the rotor 1 is changed by arranging the slits 7a unbalanced in the circumferential direction. 7B and 7C, the description of the slit 7b is omitted, but the slit 7b may be provided as in FIG.

  The rotor core 2 of the rotor 1 in the present embodiment is made of a magnetic material and is configured by laminating thin plate members (for example, electromagnetic steel plates) having slits 7a. The center-of-gravity position can be easily adjusted by changing the thickness of the thin plate-like rotor core member in which the slits 7a are arranged in an unbalanced manner in the circumferential direction.

  In the compressor shown in FIG. 6, an arbitrary stacking thickness of the rotor core 2 of the built-in permanent magnet motor 103 is inserted into the center of gravity of the rotor core 2a and the rotor core as shown in FIG. 7B. In addition, the configuration in which the center of gravity of the shaft (output shaft) 6 does not coincide with each other enables the rotor 1 to have the function of the balance weight 24.

  Further, in the rotor core 2, only an arbitrary thickness on one side in the rotation axis direction with the middle in the rotation axis direction (position indicated by A-A in FIG. 7A) as a boundary as shown in FIG. 7A. The rotor core 2a is used. Thereby, it becomes the structure where the gravity center of the rotor part comprised with the rotor core 2a and the gravity center of the shaft 6 inserted in the rotor core do not correspond. Further, the rotor core portion on the other side in the rotation axis direction with respect to the boundary is reversed (rotated 180 degrees around the rotation axis) by rotating the rotor core 2a by an arbitrary thickness as shown in FIG. 7B. Alternatively, the rotor core 2b with the front and back reversed may be laminated.

  That is, with the middle of the stack thickness as a boundary, the rotor core member 2a in which the position of the center of gravity is biased is laminated on one side of the boundary, and the center of gravity is stacked on the other side of the boundary. The rotor core member 2a whose position is biased is reversed with respect to one side and laminated by an arbitrary stacking thickness.

  In the rotor core 2a and the rotor core 2b, the magnetic pole position (unbalance position) where the slit 7a is not provided is located on the opposite side via the shaft 6 in the rotor radial direction. Thus, by configuring the rotor core 2a on one side in the rotation axis direction, the direction of shifting the center of gravity of the rotor core with respect to the center of gravity of the shaft (output shaft) 6 and on the other side in the rotation axis direction By configuring the rotor core 2b, the direction in which the center of gravity of the rotor core is shifted from the center of gravity of the shaft 6 is opposite to the direction through the shaft 6 in the rotor radial direction.

  In this case, the rotor 1 can be provided with the function of the balance weight 24, and the magnetic imbalance is eliminated as compared with the case where the rotor iron core 2a alone is used. Can be reduced, and vibration and noise can be reduced.

  Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8: is a fragmentary sectional view which shows a rotor in the cross section perpendicular | vertical to a rotating shaft about the permanent magnet synchronous machine in the 4th Example of this invention.

  In this embodiment, the magnet housing hole and the permanent magnet have a two-layer structure of magnet housing holes 4a and 4b and permanent magnets 4a and 4b, respectively. Even when two layers of magnets are arranged per pole as shown in the figure, the same effect as in the first embodiment can be obtained by arranging the slits 7a and 7b. Here, the reason why the magnets are arranged in two layers is to increase the magnet torque by expanding the surface area of the magnet, and in the case where it is difficult to utilize the reluctance torque as in the present invention, the effect of the two-layer arrangement is particularly large. . The magnet may be a multilayer of two or more layers.

  In addition, this invention is not limited to each above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Rotor, 2, 2a, 2b ... Rotor core, 3 ... Permanent magnet, 4 ... Permanent magnet accommodation hole, 5 ... Riveting for caulking, 6 ... Shaft or crankshaft, 7a, 7b ... Slit, 9 ... Stator DESCRIPTION OF SYMBOLS 10 ... Stator iron core, 11 ... Teeth, 12 (12u1, 12u2, 12v1, 12v2, 12w1, 12w2) ... Stator coil, 13 ... Fixed scroll member, 14 ... End plate, 15 ... Spiral wrap, 16 Rotating scroll member 17 End plate 18 Spiral wrap 19 (19a, 19b) Compression chamber 20 Discharge port 21 Frame 22 Pressure vessel 23 Discharge pipe 24 ... balance weight, 25 ... oil reservoir, 26 ... oil hole, 27 ... sliding bearing, 30 ... terminal box, 103 ... permanent magnet motor.

Claims (2)

Comprising a stator having a plurality of teeth, and a rotor disposed with a gap in the radial direction with respect to the stator, and
In the permanent magnet synchronous machine, wherein the rotor is configured to be convex radially inward, and a plurality of magnetic poles configured by a magnet housing hole and a permanent magnet inserted into the magnet housing hole are arranged in the circumferential direction.
A linear-axis inductance Ld (H) and a horizontal-axis inductance Lq (when the stator coil is energized with the interlinkage magnetic flux Ψp (WB) for one phase of the stator coil by the permanent magnet and the current effective value Irms (Arms). H) and the current effective value Irms (Arms),

Relationships satisfied, which and is arranged slits formed of non-magnetic material radially outer peripheral portion of the pole,
The permanent magnet is a ferrite magnet, and the ferrite magnet constituting one pole has two bending points in the circumferential direction, and two linear portions extending from the respective bending points to the radially outer peripheral side. , And the two linear portions are arranged on a center line passing through the rotation center of the rotor and the magnetic pole center of the magnetic pole so that the distance between the two linear portions increases toward the radially outer peripheral side. Inclined with respect to,
The slit is formed in an arc shape so as to draw a convex curve toward the center line, and is provided on at least one side of the center line. The permanent magnet synchronous machine is formed to be inclined with respect to the center line so as to be close to the center line . In the permanent magnet synchronous machine according to claim 1 ,
The slit is formed symmetrically with respect to the center line on both sides of the center line.

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