JP2005117771A - Permanent magnet type synchronous motor and compressor using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet type synchronous motor which is equipped with a rotor structure capable of securing necessary induced electromotive force without increasing iron loss and capable of reducing the modulus of waveform distortion. <P>SOLUTION: In the permanent magnet type synchronous motor 24 which is equipped with a rotor 1 having cage coils 3 and permanent magnets 4 arranged on the internal perimeter side of cage coil bars, the permanent magnets 4 are magnetized so that the ratio θ/α of the peripheral pitch angle θ of magnetic flux distribution of the permanent magnet 4 to the pitch angle α of magnetic poles may be 0.54 to 0.67. Therefore, the distortion of induced electromagnetic force is little, and it approximates sine waveform, so an efficient permanent magnetic type synchronous motor can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a permanent magnet type synchronous motor and a compressor using the same.

  The advantage of the induction motor is that it has a robust structure and can be directly started by a commercial power supply, so that it can be configured at a low cost as a drive source for a constant-speed drive machine that does not require speed control.

  On the other hand, synchronous motors, like induction motors, can be configured with a drive unit at a low cost and have almost no secondary copper loss during steady operation, which has the advantage of greatly contributing to higher drive system efficiency. . However, as a disadvantage, the starting cage winding is provided on the outer peripheral side of the rotor, and a permanent magnet needs to be further arranged on the inner peripheral side of the cage conductor, and the space for magnet arrangement is limited. As a result, there are design problems such as an increase in leakage magnetic flux between the magnetic poles and a difficulty in making the induced electromotive force waveform sinusoidal.

  As a method of determining the arrangement of the permanent magnets embedded in the rotor, there are techniques disclosed in Patent Document 1, Patent Document 2, and the like. These are aimed at optimizing the number and structure of the magnetic poles of a synchronous motor for application to systems such as electric vehicles.

JP-A-11-103548

JP 2002-369422 A

  When a self-starting and permanent magnet type synchronous motor is designed for a compressor according to the above-described prior art, on the one hand, the amount of magnets is too large and the iron loss increases, and on the other hand, the amount of magnets is too small and desired. The induced electromotive force for generating the output is insufficient. In the latter case, the waveform distortion is often increased, which often leads to characteristic deterioration.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a permanent magnet synchronous motor and a rotor thereof having a rotor structure that can secure a necessary induced electromotive force without increasing iron loss and reduce a waveform distortion rate, or use thereof. Is to provide a compressor.

  In one aspect of the present invention, in the permanent magnet synchronous motor, the ratio θ / α between the circumferential pitch angle θ of the permanent magnet embedded in the inner periphery of the cage winding provided on the rotor and the magnetic pole pitch angle α is , 0.54 to 0.67.

  In another aspect of the present invention, in the permanent magnet type synchronous motor, the ratio of the circumferential pitch angle θ of the magnetic flux distribution of the permanent magnet embedded in the inner periphery of the cage winding provided in the rotor and the magnetic pole pitch angle α. The permanent magnet is magnetized so that θ / α is 0.54 to 0.67.

  ADVANTAGE OF THE INVENTION According to this invention, a permanent magnet synchronous motor provided with the rotor structure which can ensure a required induced electromotive force and can reduce a waveform distortion rate without increasing a core loss can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a radial sectional view of a rotor of a synchronous motor according to a first embodiment of the present invention. In the figure, a rotor 1 includes a large number of squirrel cage windings 3 and a permanent magnet 4 mainly composed of a rare earth embedded in a magnet insertion hole 7 in a rotor core 2 provided on a shaft 6. Are arranged so that the number of magnetic poles is two. In addition, holes 5 are provided between the magnetic poles. The width opening θ of the permanent magnet 4 is 0.54 <θ / α <0.67 with respect to the magnetic pole pitch angle α, and the orientation of the magnet is a radial orientation. Reference numeral 5 denotes a hole provided between the magnetic poles.

  FIG. 2 is a conceptual diagram of the upper half obtained by adding the magnetized state of the magnet to FIG. As shown by the arrows in the figure, the magnetization direction of the permanent magnet 4 is the radial direction (radial direction) of the rotor 1.

  The width opening of the permanent magnet 4 and the circumferential pitch angle of the magnetic flux distribution of the permanent magnet 4 may be different depending on the magnetization. However, in this embodiment, as shown in FIG. 2, the permanent magnet 4 is magnetized to the full width opening, and the circumferential pitch angle of the magnetic flux distribution of the permanent magnet 4 is the width opening of the permanent magnet 4. And both are angles θ.

  FIG. 3 is a graph showing measured data of induced electromotive force waveform distortion. The horizontal axis represents the ratio θ / α of the magnetic flux pitch angle θ and the magnetic pole pitch angle α, and the vertical axis represents the induced electromotive force waveform distortion rate (%).

  When the width opening θ of the permanent magnet 4 is equal to the magnetic pole pitch angle α, the magnetic flux distribution (not shown) created by the permanent magnet 4 becomes a substantially square wave. Become. Therefore, the relationship between the width opening θ of the permanent magnet 4 and the magnetic pole pitch α was investigated. If the induced electromotive force waveform distortion is within 6%, it can be said that the characteristics are good. If the data of FIG. 3 is seen from this viewpoint, the ratio θ / α between the width opening θ and the magnetic pole pitch α is better than 0.54 and smaller than 0.67. When the ratio is 0.6, the most excellent characteristics are obtained. Based on this result, the circumferential pitch angle of the permanent magnet 4 or the circumferential pitch angle θ of the magnetic flux distribution created by the permanent magnet 4 is configured to be 0.54 to 0.67 of the magnetic pole pitch angle α.

  In other words, the circumferential pitch of the permanent magnet 4 that is the length of the permanent magnet 4 or the circumferential pitch Tm of the magnetic flux distribution created by the permanent magnet 4 is the magnetic pole pitch Tp that is the circumferential length of a semicircle on the circumference. It is comprised so that it may become 0.54-0.67.

  Here, the reason why the waveform is made sinusoidal by setting the ratio θ / α between the circumferential pitch angle θ of the permanent magnet and the magnetic pole pitch angle α as described above is as follows. Since the stator coil is wound at a 180 ° pitch, if the magnetic flux distribution is 180 ° in the case of two poles, the shape is distributed in a substantially square wave when viewed from the stator side. In this case, harmonics such as the fifth and seventh orders are superimposed on the waveform. On the other hand, when the magnetic flux distribution is made extremely smaller than 180 °, since a pulse-like waveform is obtained when viewed from the stator side, many harmonics are also superimposed. That is, the magnetic flux pitch of the magnetic flux distribution of the magnet needs to be the optimum circumferential pitch angle θ of the permanent magnet with respect to the stator winding pitch, that is, the magnetic pole pitch (for example, 180 ° in the case of two poles). ing. According to the experiments by the present inventors, as shown in FIG. 3, the case where the circumferential pitch angle θ of the magnetic flux distribution produced by the permanent magnet 4 is set to 0.54 to 0.67 of the magnetic pole pitch angle α is optimal. It was found.

  FIG. 4 is a radial sectional view of a rotor of a synchronous motor according to a second embodiment of the present invention. In FIG. 3, the same components as those in FIG. The difference from FIG. 1 is that the air holes 5 provided between the magnetic poles are divided into two so as to consist of 5A and 5B.

  If comprised in this way, the effect similar to FIG. 1 can be acquired, the path | route of a leakage magnetic flux can be decreased, and a rotor intensity | strength can be strengthened more.

  FIG. 5 is a radial sectional view of a rotor of a synchronous motor according to a third embodiment of the present invention. In FIG. 5, the same components as those in FIG. The difference from FIG. 4 is that the radius (hereinafter simply referred to as the outer diameter) r3 of the arc that forms the outer periphery of the permanent magnet 4 is shorter than the outer diameter r1 of the magnet insertion hole 7 and non-concentric. That is, the outer diameter r1 of the magnet insertion hole 7 is an arc having a radius r1 with the origin O of the shaft 6 as the center. On the other hand, the outer diameter r3 of the permanent magnet 4 is an arc having a radius r3 centered on a point O1 that is shifted from the origin O by a distance l. Here, the inner diameter of the permanent magnet 4 is the same as the inner diameter r4 of the magnet insertion hole 7.

  If an eccentric magnet is used as in this embodiment, the gap length at the circumferential end of the magnet is widened, so that the linkage of leakage magnetic flux to the stator winding near the end can be reduced, and more sinusoidal. It becomes possible to approach the wave. Therefore, according to this embodiment, the same effect as that of the second embodiment of FIG. 4 can be obtained, and the magnetic flux distribution can be made closer to a sine wave.

  FIG. 6 is an upper half sectional view in the radial direction showing the magnetized state of the magnet of the rotor according to the fourth embodiment of the present invention. In FIG. 6, the same components as those in FIGS. As shown by the arrows in the figure, the magnet orientation of the permanent magnet 4 is parallel orientation. Even with such an orientation, substantially the same characteristics as in FIGS. 1 to 5 can be obtained.

  FIG. 7 is a rotor radial cross-sectional view of a synchronous motor according to a fifth embodiment of the present invention. In FIG. 7, the same components as those in FIG. The difference from FIG. 4 is that the permanent magnet 4 is formed of a flat plate, and one magnetic pole is formed by overlapping two flat plates 4A and 4B.

  Even with this configuration, the same characteristics as in FIG. 4 can be obtained.

  FIG. 8 is a rotor radial cross-sectional view of a synchronous motor according to a sixth embodiment of the present invention. In FIG. 8, the same components as those in FIG. 7 is different from FIG. 7 in that one magnetic pole is formed by arranging three permanent magnets 4A, 4B, 4C at equal pitches in the circumferential direction.

  Even if it comprises in this way, the characteristic similar to FIG. 7 can be acquired.

  FIG. 9 is a radial cross-sectional view showing a first embodiment of a permanent magnet type synchronous motor according to the present invention. In FIG. 9, the same components as those in FIGS. FIG. 9 shows an example in which the rotor 1 that has been described in detail so far is combined with the stator 8 to form a synchronous motor 24, and the rotor of FIG. 4 is combined.

  Here, the stator 8 includes a stator core 9, a large number (24 in the drawing) of slots 10, and teeth 11 divided by these slots 10. An armature winding 12 composed of a U-phase winding 12A, a V-phase winding 12B, and a W-phase winding 12C is wound with distributed windings in which the same phase is distributed in a number of slots 10.

  In such a configuration, if an AC voltage having a constant frequency is supplied to the armature winding 12, the rotor 1 can be started and accelerated as an induction motor, and thereafter can be operated at a constant speed as a synchronous motor.

  FIG. 10 is a radial sectional view showing a second embodiment of the permanent magnet type synchronous motor according to the present invention. The same components as those in FIG. 9 are denoted by the same reference numerals, and redundant description is avoided. 10 is different from FIG. 9 in that six slots 10 of the stator 8 are configured.

  Even if configured in this manner, the same operation as that of FIG. 9 can be obtained, and since the configuration is simple, an inexpensive synchronous motor 24 can be provided.

  FIG. 11 is a radial sectional view showing a third embodiment of the permanent magnet type synchronous motor according to the present invention. The same components as those in FIG. 9 are denoted by the same reference numerals, and redundant description is avoided. 11 differs from FIG. 9 in that the number of slots 10 of the stator 8 is three, and the armature winding 12 is configured by concentrated winding wound around the teeth 11. .

  Even if configured in this manner, the same operation as that of FIG. 9 can be obtained, and a simple configuration such as shortening of a coil end (not shown) and reduction of the amount of copper can be achieved. 24 can be provided.

  In addition, although the rotor 1 in the permanent magnet type synchronous motor of the embodiment of FIGS. 9 to 11 is the rotor 1 of the embodiment described in FIG. 4, the rotor 1 described in other drawings may be used. Needless to say, the permanent magnet synchronous motor has the same effect.

  FIG. 12 is a sectional structural view of a compressor according to an embodiment of the present invention. In FIG. 12, the compression mechanism portion is formed by meshing 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 orbiting scroll member 16. . Then, the orbiting scroll member 16 is rotated by the crankshaft 6 to perform the compression operation.

  Of the compression chambers 19 (19 a, 19 b,...) Formed by the fixed scroll member 13 and the orbiting scroll member 16, the compression chamber 19 located on the outermost diameter side has both scroll members 13 along with the orbiting motion. , 16 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 a 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 a discharge pipe provided on the side wall of the pressure vessel 22. 23 is discharged out of the compressor. As described with reference to FIGS. 1 to 11, a permanent magnet type synchronous motor 24 composed of the stator 8 and the rotor 1 is enclosed in the pressure vessel 22, rotates at a constant speed, and is compressed. Perform the action.

  An oil sump 25 is provided below the synchronous motor 24. Oil in the oil sump 25 passes through an oil hole 26 provided in the crankshaft 6 due to a pressure difference caused by rotational movement, and the sliding portion between the orbiting scroll member 16 and the crankshaft 6, the sliding bearing 27, etc. Used for lubrication.

  As described above, if the permanent magnet type synchronous motor described with reference to FIGS. 1 to 11 is applied as the compressor driving motor, high efficiency of the constant speed compressor can be realized.

  According to the above embodiment, a permanent magnet synchronous motor and a rotor thereof having a rotor structure capable of ensuring a necessary induced electromotive force and reducing a waveform distortion rate without increasing iron loss, or these rotors. Can be provided.

The radial direction sectional view of the rotor of the synchronous motor by the 1st example of the present invention. The conceptual diagram of the upper half which added the magnetized state of the magnet to FIG. The graph which shows the measurement data of an induced electromotive force waveform distortion. The radial direction sectional view of the rotor of the synchronous motor concerning the 2nd example of the present invention. The radial direction sectional view of the rotor of the synchronous motor by the 3rd example of the present invention. The radial direction upper half sectional view which shows the magnetized state of the magnet of the rotor by the 4th Example of this invention. The radial direction sectional view of the rotor of the synchronous motor by the 5th example of the present invention. Radial direction sectional drawing of the rotor of the synchronous motor by the 6th Example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Radial direction sectional drawing which shows the 1st Example of the permanent-magnet-type synchronous motor by this invention. The radial direction sectional view showing the 2nd example of the permanent magnet type synchronous motor by the present invention. The radial direction sectional view showing the 3rd example of the permanent magnet type synchronous motor by the present invention. The cross-section figure of the compressor by one Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Rotor, 2 ... Rotor core, 3 ... Cage type | mold winding, 4 ... Permanent magnet, 5 ... Hole, 6 ... Shaft or crankshaft, 7 ... Magnet insertion hole, 8 ... Stator, 9 ... Stator Iron core, 10 ... slot, 11 ... teeth, 12 ... armature winding, 13 ... fixed scroll member, 14 ... end plate, 15 ... spiral wrap, 16 ... orbiting scroll member, 17 ... end plate, 18 ... spiral wrap DESCRIPTION OF SYMBOLS 19 ... Compression chamber, 20 ... Discharge port, 21 ... Frame, 22 ... Pressure vessel, 23 ... Discharge pipe, 24 ... Synchronous motor, 25 ... Oil reservoir, 26 ... Oil hole, 27 ... Sliding bearing.

Claims (20)

  A large number of slots provided in the axial direction in the vicinity of the outer periphery of the rotor core, conductive bars embedded in these slots, conductive end rings that short-circuit these bars at the axial end faces, In a permanent magnet type synchronous motor including a rotor having a permanent magnet embedded in a magnet insertion hole arranged on the inner peripheral side, a ratio θ / α of a circumferential pitch angle θ of the permanent magnet and a magnetic pole pitch angle α is: A permanent magnet type synchronous motor characterized by having a value of 0.54 to 0.67.   2. The permanent magnet type synchronous motor according to claim 1, wherein a ratio Tm / Tp between the circumferential pitch Tm and the magnetic pole pitch Tp of the permanent magnet is 0.54 to 0.67.   2. The permanent magnet synchronous motor according to claim 1, wherein a substantially arc-shaped permanent magnet is embedded in a substantially arc-shaped magnet insertion hole arranged on the inner peripheral side of the bar.   The permanent magnet synchronous motor according to claim 1, wherein a hole is provided between adjacent magnetic poles of the rotor.   2. The permanent magnet synchronous motor according to claim 1, wherein an outer diameter of the permanent magnet is formed concentrically with respect to an outer diameter of the magnet insertion hole.   6. The permanent magnet synchronous motor according to claim 5, wherein a hole is provided between adjacent magnetic poles of the rotor.   The permanent magnet synchronous motor according to claim 1, wherein the magnetic domain orientation of the permanent magnet is a radial orientation.   The permanent magnet synchronous motor according to claim 1, wherein the magnetic domain orientation of the permanent magnet is a parallel orientation.   The permanent magnet synchronous motor according to claim 1, wherein the permanent magnet is formed of a flat plate.   The permanent magnet synchronous motor according to claim 9, wherein a hole is provided between adjacent magnetic poles of the rotor.   2. The permanent magnet type synchronous motor according to claim 1, wherein the material of the permanent magnet is a rare earth magnet.   2. The permanent magnet synchronous motor according to claim 1, further comprising a stator having a stator winding wound in distributed winding in at least six slots.   The permanent magnet synchronous motor according to claim 1, further comprising a stator having a stator winding wound in a concentrated winding in three or more slots.   In a compressor having a compression mechanism section that sucks in and compresses and discharges refrigerant, and a drive motor that drives the compression mechanism section, the drive motor includes a number of slots provided in the axial direction in the vicinity of the outer peripheral portion of the rotor core. And a conductive bar embedded in these slots, a conductive end ring that short-circuits these bars at the axial end face, and a rotor having a permanent magnet disposed on the inner peripheral side of the bar, A compressor comprising a permanent magnet type synchronous motor in which a ratio θ / α of a circumferential pitch angle θ of the permanent magnet and a magnetic pole pitch angle α is set to 0.54 to 0.67.   A large number of slots provided in the axial direction in the vicinity of the outer periphery of the rotor core, conductive bars embedded in these slots, conductive end rings that short-circuit these bars at the axial end faces, In the rotor of a permanent magnet type synchronous motor provided with a permanent magnet embedded in a magnet insertion hole arranged on the inner peripheral side, the ratio θ / α between the circumferential pitch angle θ of the permanent magnet and the magnetic pole pitch angle α is set to 0 A rotor of a permanent magnet type synchronous motor, characterized in that it is .54 to 0.67.   A large number of slots provided in the axial direction in the vicinity of the outer periphery of the rotor core, conductive bars embedded in these slots, conductive end rings that short-circuit these bars at the axial end faces, In the permanent magnet type synchronous motor including a rotor having a permanent magnet embedded on the inner peripheral side, a ratio θ / α of the circumferential pitch angle θ of the magnetic flux distribution of the permanent magnet and the magnetic pole pitch angle α is set to 0.54. A permanent-magnet synchronous motor characterized by being magnetized so as to be -0.67.   17. The permanent magnet synchronous motor according to claim 16, wherein a ratio Tm / Tp of the circumferential pitch Tm and the magnetic pole pitch Tp in the magnetic flux distribution of the permanent magnet is 0.54 to 0.67. .   17. The permanent magnet type synchronous motor according to claim 16, wherein a substantially arc-shaped permanent magnet is embedded in a substantially arc-shaped magnet insertion hole arranged on the inner peripheral side of the bar.   The permanent magnet synchronous motor according to claim 16, wherein an outer diameter of the permanent magnet is formed non-concentrically with respect to an outer diameter of the magnet insertion hole. A large number of slots provided in the axial direction in the vicinity of the outer periphery of the rotor core, conductive bars embedded in these slots, conductive end rings that short-circuit these bars at the axial end surfaces, In the rotor of a permanent magnet type synchronous motor having a permanent magnet embedded on the inner peripheral side, the ratio θ / α of the circumferential direction pitch angle θ of the magnetic flux distribution of the permanent magnet to the magnetic pole pitch angle α is set to 0.54˜ A permanent magnet synchronous motor rotor characterized by being magnetized to 0.67.

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