JP5248382B2 - Permanent magnet motor, motor control system, and washing machine - Google Patents

Description

  The present invention relates to a permanent magnet motor including a plurality of permanent magnets inside a rotor core, a motor control system including the permanent magnet motor, and a washing machine including the motor control system.

In this type of permanent magnet motor, the amount of magnetic flux (interlinkage magnetic flux) of the permanent magnet interlinked with the stator winding according to the load driven by the permanent magnet motor (for example, the drum of a drum type washing and drying machine). Proper adjustment is desired.
However, the permanent magnet provided in the permanent magnet motor is generally constituted by one type, and therefore the amount of magnetic flux of the permanent magnet is always constant. In this case, for example, if only a permanent magnet having a large coercive force is used, the induced voltage due to the permanent magnet at the time of high-speed rotation becomes extremely high, which may cause dielectric breakdown of electronic components. On the other hand, if it comprises only a permanent magnet with a small coercive force, the output at the time of low speed rotation will fall.

  Therefore, for example, in the permanent magnet motor described in Patent Document 1, two types of permanent magnets having different coercive forces are arranged in the rotor core, and the magnetization state of the permanent magnet having a small coercive force is caused by the armature reaction. It is demagnetized or magnetized by an external magnetic field (a magnetic field generated by a current flowing through the stator winding), thereby adjusting the amount of magnetic flux of the permanent magnet.

JP 2006-280195 A

  In the permanent magnet motor described in Patent Document 1 described above, both a permanent magnet having a large coercive force and a small permanent magnet are disposed in a portion constituting one magnetic pole inside the rotor core. That is, since one magnetic pole is formed of a plurality of types of permanent magnets, the number of permanent magnets must be increased and the volume of each permanent magnet must be reduced, resulting in a complicated structure. Therefore, in recent years, a permanent magnet motor having a structure in which two types of permanent magnets having different coercive forces are arranged one by one for each magnetic pole and the structure is simplified has been considered.

  However, in a permanent magnet motor having a configuration in which two types of permanent magnets having different coercive forces are arranged one for each magnetic pole, that is, a configuration in which a plurality of permanent magnets forming a magnetic pole include permanent magnets having a small coercive force. Compared to the case where only permanent magnets having a large magnetic force are used, the total amount of magnetic flux of the entire permanent magnet motor is reduced, and the output of the permanent magnet motor is reduced.

  Here, if the ratio of the permanent magnets having a small coercive force among the plurality of permanent magnets is appropriately reduced, a decrease in the total magnetic flux of the entire permanent magnet motor can be suppressed. However, if the ratio of permanent magnets having a small coercive force, that is, permanent magnets whose magnetization state is easily adjusted by an external magnetic field due to armature reaction, is reduced, the adjustment range of the amount of magnetic flux of the permanent magnets is reduced.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to adjust the amount of magnetic flux of a permanent magnet according to a load to be driven, one type of permanent magnets having different coercive forces per magnetic pole. A permanent magnet motor capable of increasing the adjustment range of the magnetic flux amount of the permanent magnet without lowering the ratio of the permanent magnet having a small coercive force, and the permanent magnet motor, which is realized by a simple configuration arranged one by one. Another object is to provide a motor control system and a washing machine equipped with the motor control system.

  The permanent magnet motor of the present invention has a stator and a rotor core made of a soft magnetic material, a rotor provided rotatably with respect to the stator, and a plurality of magnetic poles inside the rotor core. The permanent magnet is formed of a plurality of types of permanent magnets having different coercive forces, and the plurality of types of permanent magnets are arranged to be one type per magnetic pole. The surface area of the surface of the magnet facing the stator is different between the permanent magnet having a relatively small coercive force and the permanent magnet having a relatively large coercive force. Yes.

  A motor control system according to the present invention includes the permanent magnet motor according to any one of claims 1 to 6 and a control unit that controls driving of the permanent magnet motor. It is characterized in that it is configured to switch the magnetization state of the small permanent magnet.

  A washing machine of the present invention includes the motor control system according to claim 7 and is configured to switch the magnetization state of the permanent magnet having a relatively small coercive force for each driving stroke by the control unit of the motor control system. It has the feature.

  According to the permanent magnet motor of the present invention, the surface area of the surface where the permanent magnet having a relatively small coercive force faces the stator is larger than the surface area of the surface where the permanent magnet having a relatively large coercive force faces the stator. By making the difference greatly, the adjustment range of the magnetic flux amount of the permanent magnet can be increased without reducing the ratio of the permanent magnet having a small coercive force.

According to the motor control system of the present invention, the amount of magnetic flux of the permanent magnet can be adjusted efficiently.
According to the washing machine of the present invention, the amount of magnetic flux of the permanent magnet can be efficiently adjusted for each driving stroke.

BRIEF DESCRIPTION OF THE DRAWINGS The 1st Embodiment of this invention is shown, The perspective view which shows schematically the whole structure of a permanent magnet motor The perspective view which shows the structure of a stator roughly The perspective view which shows the structure of a rotor roughly Partial enlarged view showing an enlarged part of the rotor Longitudinal side view schematically showing the internal structure of the drum type washing and drying machine Block diagram schematically showing the electrical configuration of the drum-type washing and drying machine FIG. 3 equivalent view according to the second embodiment of the present invention. 4 equivalent figure

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view schematically showing the overall configuration of a permanent magnet motor 1 (outer rotor type brushless motor). The permanent magnet motor 1 is composed of a stator 2 and a rotor 3 provided on the outer periphery of the stator 2 so as to be rotatable with respect to the stator 2.

  As shown in FIG. 2, the stator 2 includes a stator core 4 and a stator winding 5. The stator core 4 is formed by laminating and caulking a plurality of punched and formed soft magnetic bodies of silicon steel plates and projecting radially from an annular yoke portion 4a and an outer peripheral portion of the yoke portion 4a. And a large number of teeth 4b. The surface of the stator core 4 is covered with PET resin (mold resin) except for an outer peripheral surface 4c (a tip surface of each tooth portion 4b) that forms a gap with the inner peripheral surface of the rotor 3. A plurality of attachment portions 6 made of PET resin are integrally formed on the inner peripheral portion of the stator 2. These attachment portions 6 are provided with a plurality of screw holes 6a. By fixing these attachment portions 6 to each other, the stator 2 is in this case a water tank 25 of the drum type washing and drying machine 21 (see FIG. 5). It is supposed to be fixed to the back of the. In this case, the stator winding 5 is composed of three phases and is wound around each tooth portion 4b.

  As shown in FIG. 3, the rotor 3 has a configuration in which the frame 7, the rotor core 8, and the plurality of permanent magnets 9 are integrated with a mold resin (not shown). The frame 7 is formed into a flat bottomed cylindrical shape by pressing, for example, an iron plate, which is a magnetic body, and stands up from a circular main plate portion 7a and a stepped portion 7b from the outer peripheral portion of the main plate portion 7a. And an annular peripheral side wall 7c. A shaft mounting portion 10 for mounting the rotating shaft 26 (see FIG. 5) is provided at the center of the main plate portion 7a, and a plurality of ventilation holes are provided between the shaft mounting portion 10 and the step portion 7b. 11 and ribs 12 are formed radially about the shaft mounting portion 10.

  The rotor core 8 has a substantially annular shape as a whole, and is formed by laminating and caulking a number of silicon steel plates that are punched and formed of soft magnetic materials. The rotor core 8 is disposed on the inner peripheral portion of the peripheral side wall 7 c of the frame 7. The inner peripheral surface of the rotor core 8 (the surface that faces the outer peripheral surface of the stator 2 (the outer peripheral surface 4c of the stator core 4) and forms a gap between the stator 2) faces inward. It is formed in a concavo-convex shape having a plurality of convex portions 8a protruding in an arc shape. These convex portions 8a are portions where magnetic poles are formed by permanent magnets 9 arranged one by one on the convex portion 8a.

  As shown in FIG. 4, a plurality of insertion holes 13 that penetrate the rotor core 8 in the axial direction (lamination direction of the silicon steel plates) are respectively formed in the plurality of convex portions 8a. The insertion hole 13 is arranged in an annular shape in the rotor core 8. The plurality of insertion holes 13 are composed of two types of insertion holes 13a and 13b having different opening shapes. These insertion holes 13 a and 13 b are alternately arranged along the circumferential direction of the rotor core 8. In this case, the insertion hole 13a is opened in a rectangular shape that is long in the circumferential direction of the rotor core 8, and its dimension in the short side direction (the radial direction of the permanent magnet motor 1) is 2.1 mm, and the long side direction (permanently). The dimension in the circumferential direction of the magnet motor 1 is 12.0 mm, and the dimension in the depth direction (axial direction of the permanent magnet motor 1) is 19.0 mm. In addition, the dimension of each direction of the insertion hole 13a can be changed and set suitably. On the other hand, the insertion hole 13b is composed of two insertion holes 13b 'opened in a rectangular shape, and these two insertion holes 13b' are arranged in the circumferential direction so that the inner peripheral side (stator 2 side) is opened and the outer peripheral side is closed. It opens in an inclined state (substantially V-shaped). In addition, the dimension of each direction of these insertion holes 13b ', the inclination angle with respect to the circumferential direction, and the like can be appropriately changed and set.

  The permanent magnet 9 includes a rectangular flat-plate neodymium magnet 9a which is a high coercive permanent magnet having a large coercive force, and a samacoba magnet 9b (samarium / cobalt magnet) which is a low coercive permanent magnet having a small coercive force. . That is, each of the permanent magnets 9a and 9b is composed of a neodymium magnet and a sumaboba magnet which are rare earth magnets. In this case, the coercive force of the neodymium magnet 9a is about 900 kA / m, the coercive force of the sumakoba magnet 9b is about 200 to 500 kA / m, and the coercive force differs by about 1.8 to 4.5 times. That is, the permanent magnet 9 is composed of two types of permanent magnets 9a and 9b having different coercive forces. These permanent magnets 9a and 9b are arranged in a ring-like manner in the rotor core 8 alternately in the circumferential direction, and one kind for one convex portion 8a (insertion hole 13a portion or insertion hole 13b portion). It is arranged one by one.

  The neodymium magnet 9a forms one magnetic pole by one permanent magnet 9a inserted into the insertion hole 13a. That is, the neodymium magnet 9a is composed of one permanent magnet per magnetic pole. On the other hand, the Samakoba magnet 9b forms one magnetic pole by two rectangular flat plate-like permanent magnets 9b 'inserted into the insertion holes 13b (two insertion holes 13b'). That is, the Samakoba magnet 9b is composed of two permanent magnets per magnetic pole. The neodymium magnet 9a is in a state in which almost the entire area of the peripheral side portion is surrounded and held by the soft magnetic rotor core 8 (insertion hole 13a portion). In addition, the Samacoba magnet 9b (two Samacoba magnets 9b ′) is surrounded and held by a soft magnetic rotor core 8 (insertion hole 13b (two insertion holes 13b ′) portion) in almost the entire circumferential side. It is in the state.

  In addition, the summer magnet 9b (two summer magnets 9b ') is inserted into the insertion hole 13b (two insertion holes 13b'), so that the inner peripheral side (stator 2 side) is opened and the outer peripheral side is closed. It is arranged in a state inclined in the direction (substantially V-shaped). Therefore, the permanent magnet motor 1 is configured such that the surface areas of the surfaces where the permanent magnets 9a and 9b face the stator 2 are different between the small coke magnet 9b having a small coercive force and the neodymium magnet 9a having a large coercive force. Moreover, in this case, the surface area of the surface where the coercive magnet 9b having a small coercive force faces the stator 2 is configured so that the surface area of the neodymium magnet 9a having a large coercive force faces the surface of the stator 2 is larger. ing.

  Note that the neodymium magnet 9a has a high coercive force and the Samakova magnet 9b has a low coercive force because the external magnetic field (current flowing through the stator winding 5) from the stator 2 (stator winding 5) due to the armature reaction. In the standard that the magnetization amount of the neodymium magnet 9a does not change at a current that can change the magnetization amount of the Samacoba magnet 9b when the magnetic field generated by This is called low coercivity.

  Further, as described above, each of these two types of permanent magnets 9a and 9b forms one magnetic pole with one type of permanent magnet. And the neodymium magnet 9a is arrange | positioned so that the magnetization direction may follow the radial direction of the permanent magnet motor 1 (direction which goes to the space | gap between the outer peripheral part of the permanent magnet motor 1 between the stator 2 and the rotor 3). . On the other hand, the summer magnet 9b is arranged so that its magnetization direction is substantially along the radial direction of the permanent magnet motor 1.

  Thus, by arranging the two types of permanent magnets 9a and 9b alternately and so that their magnetization directions are almost along the radial direction, the permanent magnets 9a and 9b arranged next to each other are magnetic poles in opposite directions. (One N pole is inside and the other N pole is outside), and a magnetic path (for example, in the direction indicated by an arrow B (see FIG. 3) between the neodymium magnet 9a and the Samacoba magnet 9b. Magnetic flux). Note that an arrow indicated by a broken line in FIG. 3 is a magnetic flux passing through the rotor core 8.

  With such a configuration, a magnetic path is formed that passes through both the neodymium magnet 9a having a large coercive force and the sumakoba magnet 9b having a small coercive force. In this case, the permanent magnet motor 1 has a 48-pole / 36-slot configuration (a configuration in which 36 teeth 4b are provided for 48 permanent magnets 9), and 4 poles per 3 slots. Corresponds to (4-pole / 3-slot configuration).

  Next, the structure of the drum type washing / drying machine 21 provided with the permanent magnet motor 1 configured as described above will be described. FIG. 5 is a longitudinal side view schematically showing the internal configuration of the drum-type washing / drying machine 21.

  The outer box 22 forming the outer shell of the drum-type washing / drying machine 21 has a laundry entrance / exit 23 opened in a circular shape on the front surface. The laundry entrance / exit 23 is opened and closed by a door 24. ing. Inside the outer box 22, a bottomed cylindrical water tank 25 with a closed back surface is disposed, and the permanent magnet motor 1 (stator 2) is screwed to the center of the back surface of the water tank 25. It is fixed. The rotating shaft 26 of the permanent magnet motor 1 has a rear end portion (right end portion in FIG. 5) fixed to the shaft mounting portion 10 of the permanent magnet motor 1 (rotor 3), and a front end portion (in FIG. 5). The left end) protrudes into the water tank 25. A bottomed cylindrical drum 27 whose back is closed is fixed to the front end of the rotating shaft 26 so as to be coaxial with the water tank 25, and this drum 27 is driven by the permanent magnet motor 1. It rotates integrally with the rotor 3 and the rotating shaft 26. The drum 27 is provided with a plurality of flow holes 28 through which air and water can flow, and a plurality of baffles 29 for scraping and unraveling the laundry in the drum 27.

  A water supply valve 30 is connected to the water tank 25, and water is supplied into the water tank 25 when the water supply valve 30 is opened. Further, a drain hose 32 having a drain valve 31 is connected to the water tank 25, and when the drain valve 31 is opened, water in the water tank 25 is discharged.

  A ventilation duct 33 extending in the front-rear direction is provided below the water tank 25. A front end portion of the ventilation duct 33 is connected to the water tank 25 via the front duct 34, and a rear end portion is connected to the water tank 25 via the rear duct 35. A blower fan 36 is provided at the rear end portion of the ventilation duct 33, and the air in the water tank 25 is moved from the front duct 34 into the ventilation duct 33 by the blowing action of the blower fan 36 as indicated by an arrow. And is returned to the water tank 25 through the rear duct 35.

  An evaporator 37 is disposed on the front side inside the ventilation duct 33, and a condenser 38 is disposed on the rear side. The evaporator 37 and the condenser 38 constitute a heat pump 40 together with the compressor 39 and a throttle valve (not shown), and the air flowing in the ventilation duct 33 is dehumidified by the evaporator 37 and heated by the condenser 38. And is circulated in the water tank 25.

  An operation panel 41 is provided on the front surface of the outer box 22 above the door 24. The operation panel 41 is provided with a plurality of operation switches (not shown) for setting a driving course and the like. ing. The operation panel 41 is composed mainly of a microcomputer and is connected to a control circuit unit 42 (corresponding to a control unit) that controls the overall operation of the drum-type washing and drying machine 21, and the control circuit unit 42 is connected to the operation panel 41. Various operation courses are executed while controlling the drive of the permanent magnet motor 1, the water supply valve 30, the drain valve 31, the compressor 39, the throttle valve, and the like according to the contents and control programs set via the control.

  Further, a magnetic sensor 43 (see FIG. 6) that detects the magnetism of the permanent magnet 9 is arranged at a portion facing the permanent magnet 9 in the permanent magnet motor 1. The magnetic sensor 43 is mounted on a circuit board (not shown) attached to the stator 2 side. As shown in FIG. 6, the control circuit unit 42 calculates the rotational position of the rotor 3 based on the detection signal from the magnetic sensor 43. Then, an inverter circuit 44 in which six IGBTs 44a (only two are shown in FIG. 6) are connected in a three-phase bridge is driven by a gate drive signal G corresponding to the calculation result, whereby the stator winding 5 The rotor 3 is rotated while controlling the energization. The control circuit unit 42 constitutes the motor control system 45 of the present invention together with the permanent magnet motor 1.

Next, the operation of the drum type washer / dryer 21 provided with the permanent magnet motor 1 as described above will be described.
When the control circuit unit 42 of the motor control system 45 energizes the stator winding 5 via the inverter circuit 44, an external magnetic field (magnetic field generated by the current flowing through the stator winding 5) due to the armature reaction is generated in the rotor 3. The permanent magnets 9a and 9b are acted on. Of these permanent magnets 9 a and 9 b, the magnetization state of the small coke magnet 9 b having a small coercive force is demagnetized or increased by an external magnetic field due to this armature reaction, and thereby interlinks with the stator winding 5. The amount of magnetic flux (interlinkage magnetic flux amount) can be increased or decreased. Therefore, in the present embodiment, the motor control system 45 controls the energization of the stator winding 5 by the control circuit unit 42, thereby changing the magnetization state of the Samakoba magnet 9b in the operation process (for example, washing process, dehydration process, drying process). The process is switched and executed every time. Here, the operation content in each driving process will be described in order.

  First, in the washing process, the control circuit unit 42 opens the water supply valve 30 to supply water into the water tank 25, and then rotates the drum 27 to perform washing. In this washing process, it is necessary to rotate the drum 27 with high torque in order to scoop up the laundry containing water, but the rotation speed may be low. Therefore, the motor control system 45 controls the energization of the stator winding 5 by the inverter circuit 44 via the control circuit unit 42 so that the magnetization state of the Samakoba magnet 9b is increased. As a result, the amount of magnetic flux acting on the stator winding 5 is large (the magnetic force is strong), so that the drum 27 can be rotated at high torque and low speed.

  Next, in the dehydration process, the control circuit unit 42 opens the drain valve 31 to discharge the water in the water tank 25, and then dehydrates the moisture contained in the laundry by rotating the drum 27 at a high speed. In this dewatering process, it is necessary to rotate the drum 27 at a high speed in order to improve the dewatering efficiency, but the torque may be small. Therefore, the motor control system 45 controls the energization of the stator winding 5 by the inverter circuit 44 via the control circuit unit 42 so that the magnetization state of the Samakoba magnet 9b is demagnetized. As a result, the amount of magnetic flux acting on the stator winding 5 is reduced (the magnetic force is weak), so that the drum 27 can be rotated at a low torque and a high speed.

  Finally, in the drying process, the control circuit unit 42 dries the laundry by driving the blower fan 36 and the heat pump 40 and rotating the drum 27. In this drying process, the motor control system 45 prepares the stator winding 5 by the inverter circuit 44 via the control circuit unit 42 so that the magnetization state of the Samacoba magnet 9b is increased in preparation for the next washing process. Control energization. Thereby, it can be set as the state which increased the magnetic flux amount which acts on the stator coil | winding 5, and can make it easy to rotate the drum 27 at high torque low speed in the next washing process.

  As described above, according to the present embodiment, the permanent magnet motor 1 includes the neodymium magnet 9a having a large coercive force on the stator 2 and a surface area of the surface where the small coercive magnet 9b having a small coercive force faces the stator 2. It is comprised so that it may differ greatly from the surface area of the surface which opposes. That is, in the entire permanent magnet motor 1 and per one magnetic pole, the relationship is “the surface area of the neodymium magnet 9a on the stator 2 side <the surface area of the samakova magnet 9b on the stator 2 side”. Thereby, it is possible to secure a large area in which the external magnetic field due to the armature reaction from the stator 2 acts on the sumaboba magnet 9b, and the amount of magnetic flux of the permanent magnet 9 without reducing the proportion of the sumaboba magnet 9b having a small coercive force. The adjustment range can be increased.

  In addition, the surface area of the surface where the Sama Koba magnet 9b faces the stator 2 is changed by changing the inclination angle and the size of the two Sama Koba magnets 9b ′ having a small coercive force, and the neodymium magnet 9a is changed to the stator 2. It can be ensured by making it nearly twice as large as the surface area of the opposing surface.

  Further, since the Sama Coba magnet 9b (two Sama Coba magnets 9b ') are arranged so that the stator 2 side is opened, the magnetic flux of the Sama Coba magnet 9b is linked to the stator 2 so that the magnetic flux is concentrated at the center. It becomes like this. Thereby, the magnetic flux amount (linkage magnetic flux amount) of the sumabow magnet 9b interlinked with the stator winding 5 can be increased as compared with the case where the sumakoba magnet is arranged so that the rotor 3 side is opened.

  Also, a load that is driven by demagnetizing or increasing the magnetization state of the small coercive magnet 9b having a small coercivity among two types of permanent magnets 9a and 9b having different coercive forces by an external magnetic field due to an armature reaction (this embodiment) In the embodiment, the amount of magnetic flux of the permanent magnet 9 can be adjusted according to the drum 27) of the drum type washer / dryer 21. As a result, the amount of magnetic flux of the permanent magnet 9 is not always constant, and it is possible to prevent dielectric breakdown during high-speed rotation and output reduction during low-speed rotation.

  Moreover, the configuration in which two types of permanent magnets 9a and 9b having different coercive forces are arranged so as to be alternately and substantially annular in the circumferential direction with one type per magnetic pole is simple, and such a simple configuration Thus, the amount of magnetic flux of the permanent magnet 9 can be adjusted according to the load to be driven (drum 27).

  In addition, the magnetic path formed by the two types of permanent magnets 9a and 9b passes through both the neodymium magnet 9a having a large coercive force and the sumakoba magnet 9b having a small coercive force. Thereby, the magnetic flux amount of all the magnetic paths can be made substantially the same, and the drum 27 can be driven with a stable magnetic flux amount.

Further, according to the motor control system 45 of the present embodiment, the amount of magnetic flux of the permanent magnet 9 can be adjusted efficiently.
Moreover, according to the drum type washing / drying machine 21 of this embodiment, the magnetic flux amount of the permanent magnet 9 can be adjusted efficiently according to the driving process.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, description is abbreviate | omitted about the same part as 1st Embodiment mentioned above, and only a different part is demonstrated. The present embodiment is different from the above-described first embodiment in the shape of the Samakoba magnet 9c having a relatively small coercive force and the shape of the insertion hole 13c into which the Samakova magnet 9c is inserted.

  That is, as shown in FIG. 8, each of the insertion holes 13 formed in the plurality of convex portions 8a of the rotor core 8 is composed of an insertion hole 13a and an insertion hole 13c in place of the insertion hole 13b. ing. The insertion hole 13c is opened in a curved shape (substantially C-shaped) so that the inner peripheral side (stator 2 side) is recessed and the outer peripheral side swells.

  Moreover, the permanent magnet 9 is comprised from the neodymium magnet 9a and the Samakoba magnet 9c replaced with the above-mentioned Samakova magnet 9b. The sumaboba magnet 9c is formed in a curved shape (substantially C-shaped) so that the inner peripheral side (stator 2 side) is recessed and the outer peripheral side swells corresponding to the shape of the insertion hole 13c described above.

  The summer magnet 9c forms one magnetic pole by one permanent magnet 9c inserted into the insertion hole 13c. That is, the Samakoba magnet 9c is composed of one permanent magnet per magnetic pole. It is to be noted that almost the entire area of the peripheral side portion of the sumaboba magnet 9c is surrounded and held by the soft magnetic rotor core 8 (insertion hole 13c portion).

  Each of these two types of permanent magnets 9 a and 9 c forms one magnetic pole, and is arranged so that the magnetization direction is along the radial direction of the permanent magnet motor 1. In this way, by arranging the two types of permanent magnets 9a and 9c alternately and so that their magnetization directions are along the radial direction, the permanent magnets 9a and 9c arranged next to each other have magnetic poles in opposite directions. A magnetic path (magnetic flux) in a direction indicated by an arrow B (see FIG. 7), for example, between the neodymium magnet 9a and the Samacoba magnet 9c. ) Occurs. Note that an arrow indicated by a broken line in FIG. 7 is a magnetic flux passing through the rotor core 8. With such a configuration, a magnetic path is formed that passes through both the neodymium magnet 9a having a large coercive force and the sumakoba magnet 9c having a small coercive force.

  According to the present embodiment, in the permanent magnet motor 1, the surface area of the surface where the small coercive magnet 9c faces the stator 2 is smaller than the surface area of the surface where the neodymium magnet 9a where the coercive force is large faces the stator 2. Are also configured to be greatly different. That is, the relationship between the surface area of the permanent magnet motor 1 as a whole and one magnetic pole is “the surface area of the neodymium magnet 9a on the stator 2 side <the surface area of the samakova magnet 9c on the stator 2 side”. Thereby, it is possible to secure a large area in which the external magnetic field due to the armature reaction from the stator 2 acts on the sumaboba magnet 9c, and the amount of magnetic flux of the permanent magnet 9 without reducing the proportion of the sumaboba magnet 9c having a small coercive force. The adjustment range can be increased.

  In addition, by changing the curvature and size of the Samakoba magnet 9c having a small coercive force, the surface area of the surface where the Samacoba magnet 9c faces the stator 2 is compared with the surface area of the surface where the neodymium magnet 9a faces the stator 2. It can be ensured by making a big difference.

  Moreover, since the Samakoba magnet 9c has a shape in which the stator 2 side is depressed, the magnetic flux of the Samakova magnet 9c is linked to the stator 2 so that the magnetic flux is concentrated in the central portion. Thereby, compared with the case where it arrange | positions and arranges so that the rotor 3 side may become depressed in the rotor 3, the magnetic flux amount (linkage magnetic flux amount) of the sumakoba magnet 9c linked to the stator coil | winding 5 can be increased.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
For example, the neodymium magnet 9a is composed of two permanent magnets per magnetic pole, and these two permanent magnets are arranged in a circumferentially inclined state so that the stator 2 side opens, or the neodymium magnet 9a is fixed to the stator. By forming and arranging in a curved shape so that the two sides are recessed, the surface area of the surface where the neodymium magnet 9a having a large coercive force faces the stator 2 and the surface magnets 9b and 9c having a small coercive force face the stator 2. You may comprise so that it may differ greatly from the surface area of a surface. According to such a configuration, the total amount of magnetic flux of the entire permanent magnet motor 1 can be increased.

  Magnets that can be used as low-coercivity permanent magnets with low coercivity are not limited to the above-described sumakoba magnets 9b, 9c, and the coercivity is low enough to change the amount of magnetization by an external magnetic field due to armature reaction. Any material can be used as long as it is a permanent magnet. Examples of such a permanent magnet having a small coercive force include an alnico magnet (aluminum / nickel / cobalt magnet), a ferrite magnet, or a neodymium magnet having a relatively small coercive force. Further, the high coercive force permanent magnet having a large coercive force is not limited to the neodymium magnet 9a.

  Accordingly, the combination of the two types of permanent magnets 9 having different coercive forces is not limited to the combination of the neodymium magnet 9a and the Samakova magnets 9b and 9c, and other types such as a combination of the neodymium magnet 9a and the alnico magnet, for example. A combination of permanent magnets can be used. In addition, it is preferable that these two types of permanent magnets 9 differ in coercive force approximately twice or more.

  The permanent magnet 9 is not limited to two types, and may be composed of three types of permanent magnets having large, medium, and small coercive forces, or composed of a plurality of types of permanent magnets such as four types and five types. May be. In this case, the motor control system 45 may switch the magnetization state of the permanent magnet having a relatively small coercive force among these permanent magnets for each operation stroke by the control circuit unit 42.

The means for adjusting the amount of magnetic flux of the permanent magnet 9 is not limited to the configuration in which the energization of the stator winding 5 is controlled by the inverter circuit 44. For example, a winding different from the stator winding 5 is provided. A configuration may be adopted in which energization of the winding is controlled.
The present invention is not limited to a 48-pole / 36-slot motor, but can be applied to a motor having a 4-pole / 3-slot structure as a basic unit, or a motor having another structure as a basic unit.

  The permanent magnet motor 1 of the present invention is applicable not only to the above-described drum type washing and drying machine 21, but also to a washing machine having no drying function and a vertical washing machine in which the axial direction of the rotating tub is vertical. can do. Further, the present invention can be applied not only to the outer rotor type permanent magnet motor 1 as described above but also to an inner rotor type motor in which a rotor is rotatably provided on the inner periphery of the stator. Furthermore, the present invention can be applied to various motors such as a compressor driving motor mounted on an air conditioner or the like.

  In the drawings, 1 is a permanent magnet motor, 2 is a stator, 3 is a rotor, 8 is a rotor core, 9 is a permanent magnet, 9a is a neodymium magnet, 9b (9b ') is a Samacoba magnet, 9c is a Samakova magnet, 21 Is a drum type washing / drying machine (washing machine), 42 is a control circuit unit (control unit), and 45 is a motor control system.

Claims (9)

A stator,
A rotor core made of a soft magnetic material, and a rotor provided rotatably with respect to the stator;
A permanent magnet that forms a plurality of magnetic poles inside the rotor core;
The permanent magnet is composed of a plurality of types of permanent magnets having different coercive forces, and the plurality of types of permanent magnets are arranged to be one type per magnetic pole,
The surface area of the surface of the permanent magnet facing the stator is different between the permanent magnet having a relatively small coercive force and the permanent magnet having a relatively large coercive force. Permanent magnet motor. One of the permanent magnet having a relatively small coercive force and the permanent magnet having a relatively large coercive force is composed of two permanent magnets per magnetic pole,
2. The permanent magnet motor according to claim 1, wherein the two permanent magnets are arranged in a circumferentially inclined state so that the stator side is opened.   One of the permanent magnet having a relatively small coercive force and the permanent magnet having a relatively large coercive force is composed of a permanent magnet formed in a curved shape so that the stator side is recessed. The permanent magnet motor according to claim 1.   The permanent magnet motor according to any one of claims 1 to 3, wherein the permanent magnet is composed of two types of permanent magnets having different coercive forces.   The permanent magnet motor according to claim 4, wherein the two types of permanent magnets have a coercive force that is two or more times different.   The permanent magnet motor according to claim 4 or 5, wherein the two kinds of permanent magnets are alternately arranged in a circumferential direction. A permanent magnet motor according to any one of claims 1 to 6,
A control unit for controlling the driving of the permanent magnet motor,
A motor control system configured to switch the magnetization state of the permanent magnet having a relatively small coercive force by the control unit. A motor control system according to claim 7,
The washing machine, wherein the controller of the motor control system is configured to switch the magnetization state of the permanent magnet having a relatively small coercive force for each driving stroke.   The washing machine according to claim 8, wherein the driving process is any one of washing, dehydration, and drying.

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