JP5183601B2 - Synchronous motor rotor and synchronous motor - Google Patents

Description

  The present invention relates to a rotor of a synchronous motor having a permanent magnet in the rotor, and a synchronous motor using the rotor of the synchronous motor.

  Many common synchronous motors (hereinafter sometimes simply referred to as “motors” and “motors”) have a ratio of the number of stator slots (same as the number of teeth) to the number of rotor poles of 3: 2. On the other hand, the number of teeth for intensively winding the winding around the stator is 12 (the number of slots for storing the winding is 12), and the number of magnetic poles of the permanent magnet of the rotor (the number of poles of the rotor) is 10 synchronous motors (defined as 12-slot 10-pole synchronous motors) have a winding factor as compared with a synchronous motor in which the ratio of the number of slots of the stator to the number of poles of the rotor is 3: 2. Therefore, a large output can be obtained for the same current even with a motor of the same size.

  In other words, since the current required to output the same torque is reduced, a more efficient motor can be obtained.

  As a combination of the number of slots of the stator and the number of poles of the rotor, a combination that can provide a more efficient synchronous motor has been proposed.

  For example, in order to provide a permanent magnet field type brushless motor (synchronous motor) having a simple configuration, a small cogging torque, and a relatively large output, the number of permanent magnet magnetic poles P of the permanent magnet field and the salient pole of the stator The relation of the number M is set to (2/3) M <P <(4/3) M and M = 6n and P <6n-2 or P> 6n + 2 (where n is an integer of 2 or more) This improves both the cogging torque and the winding coefficient, that is, improves the winding coefficient (improves the output), reduces the cogging torque magnitude, and reduces the motor center. Permanent magnet field type brushless that reduces the vibration of the motor by reducing the influence of the air gap imbalance, because the armature winding wound around the salient pole poles mechanically close to 180 degrees can be selected in the same phase Motors (synchronous motors) have been proposed (examples If, see Patent Document 1).

  Further, cogging torque peculiar to a synchronous motor having a permanent magnet in the rotor is generated at a pulsation number which is the least common multiple of the number of slots of the stator and the number of magnetic poles of the rotor. In the above-described 12-slot 10-pole synchronous motor, the number of pulsations is as high as 60, the cogging torque energy is dispersed and the amplitude is reduced, and a low-noise synchronous motor can be realized.

  The pulsation (ripple) in the torque output from the motor is a factor of vibration and noise generated from the motor, and in the case of a synchronous motor using a permanent magnet, distortion is the factor in the induced voltage. On the other hand, by changing the wall thickness of the permanent magnet arranged on the rotor surface to a sine wave shape, the permanent magnet type suppresses the distortion of the induced voltage by making the magnetic flux density distribution waveform on the rotor surface a sine wave shape. A motor (synchronous motor) has been proposed (see, for example, Patent Document 2).

JP-A-10-243621 JP-A-10-234148

  However, in the description of Patent Document 1 above, regarding the combination of the number of slots of the stator of the motor and the number of magnetic poles of the rotor, the combination that increases the winding coefficient and the combination that decreases the cogging torque are described. There is no description on the combination of the induced voltage distortion, the number of slots, and the number of poles, which is one of the causes of ripple.

  Further, as described in Patent Document 2, in order to make the distribution of magnetic flux density on the rotor surface sinusoidal, for example, the shape of the magnet disposed on the rotor surface is changed to the thickness of the central portion of the magnetic pole. In some cases, the thickness is gradually increased toward the gap between the magnetic poles. In this case, the maximum value of the magnetic flux density in the gap between the rotor and the stator when the rotor and the stator are combined, in other words, the amplitude of the magnetic flux density distributed in a sinusoidal shape depends on the thickness of the magnet. Determined. For this reason, in order to increase the magnetic flux density, it is necessary to increase the thickness of the magnet, and there is a problem that the amount of magnet used increases.

  In order to make it more sinusoidal, the thickness of the magnet between the magnetic poles must be reduced, and the strength of the ring magnet is greatly reduced at that portion. In general, such magnets often have a magnetic back yoke, and if the expansion coefficient of the back yoke differs greatly from the magnet due to temperature changes in the usage environment, stress is applied to the magnet. And cracks may occur from the aforementioned thin portion.

  The present invention has been made to solve the above-described problems. A rotor of a synchronous motor and a rotor of the synchronous motor that can improve output and efficiency without increasing vibration and noise. A synchronous motor to be used is provided.

The electric motor according to the present invention is a rotor of a synchronous motor having a three-phase 12n slot and 10n pole (n is a natural number),
The magnetic flux density distribution on the rotor surface is a waveform in which the vicinity of the magnetic pole center is flat, and the magnetic flux density decreases from this flat part toward the poles.
The circumferential width of the flat portion in the vicinity of the magnetic pole center is set to 45 ° to 125 ° in electrical angle.

  In the synchronous motor according to the present invention, the magnetic flux density distribution on the rotor surface is flat in the vicinity of the magnetic pole center in a three-phase 12n slot 10n pole (n is a natural number) rotor. Since the magnetic flux density is a waveform that decreases toward the center, and the circumferential width of the flat portion near the magnetic pole center is set to 45 ° to 125 ° in electrical angle, even if the maximum value of the magnetic flux density is the same, Many primary frequency components necessary for generating torque can be included, and the synchronous motor can be increased in torque and efficiency. In addition, the synchronous motor having a combination of 12n slots and 10n poles is characterized in that distortion of the magnetic flux density distribution waveform on the rotor surface is difficult to be superimposed on the induced voltage, so that excessive torque pulsation does not occur. Does not increase noise.

FIG. 2 is a diagram illustrating the first embodiment, and is a cross-sectional view of a synchronous motor 100 having 12 slots and 10 poles. FIG. 3 shows the first embodiment, and is a connection diagram of stator windings of the synchronous motor 100. FIG. 4 is a diagram showing the first embodiment, and is a development view showing a method of connecting stator windings of the synchronous motor 100. FIG. FIG. 3 shows the first embodiment and is a cross-sectional view of a rotor 200 of the synchronous motor 100. FIG. 5 shows the first embodiment, and shows a magnetized state of a permanent magnet 210 of a rotor 200. FIG. FIG. 6 shows the first embodiment, and shows an example of a surface magnetic flux density distribution waveform of the rotor 200 of FIG. 5. FIG. 6 is a diagram illustrating the first embodiment and is a diagram comparing an induced voltage waveform of a 12-slot 10-pole synchronous motor 100 using the rotor 200 of FIG. 5 with an induced voltage waveform of a 12-slot 8-pole synchronous motor 500; In the figure which shows Embodiment 1, about the relationship between the flat part angle of the magnetic pole center of a rotor surface magnetic flux density distribution, and an induced voltage distortion rate, the synchronous motor 500 of 12 slots 8 poles and the synchronous motor 100 of 12 slots 10 poles are shown. The figure which shows the result which compared with. FIG. 9 shows the first embodiment, and shows only 12 slots and 10 poles of FIG. FIG. 3 is a diagram showing the first embodiment and shows the relationship between the flat part angle of the magnetic pole center of the rotor surface magnetic flux density distribution, the rotor surface magnetic flux waveform, and the primary component included in the induced voltage; The figure which compared 12 slots 10 poles. FIG. 5 is a diagram illustrating the first embodiment and is a diagram illustrating a relationship between a flat part angle of a magnetic pole center of a rotor surface magnetic flux density distribution waveform, an amplitude (crest value) of a surface magnetic flux density distribution waveform, and an amplitude ratio of a primary component; . FIG. 5 shows the first embodiment, and shows the relationship between the flat part angle of the magnetic pole center of the rotor surface magnetic flux density distribution waveform and the harmonic component of the rotor surface magnetic flux density. FIG. 5 shows the first embodiment, and shows a relationship between a fifth harmonic component included in the rotor surface magnetic flux waveform and a fifth harmonic component included in the induced voltage. FIG. 4 shows the first embodiment, and shows the relationship between the seventh harmonic component included in the rotor surface magnetic flux waveform and the seventh harmonic component included in the induced voltage. A cross-sectional view of a synchronous motor 500 having 12 slots and 8 poles for comparison. It is a figure shown for a comparison and it is a connection diagram of the stator winding | coil of the synchronous motor 500 of 12 slots 8 poles. The figure shown for a comparison, and the expanded view which shows the connection method of the stator winding | coil of the synchronous motor 500 of 12 slots 8 poles. The cross-sectional view of the rotor 600 of the synchronous motor 500 with 12 slots and 8 poles for comparison. FIG. 5 shows the second embodiment and is a cross-sectional view of a rotor 300. FIG. 5 shows the second embodiment, and shows a magnetized state of a permanent magnet 310 of a rotor 300. FIG. 10 shows the second embodiment and is a cross-sectional view of a rotor 400 according to a modification. FIG. 9 shows the second embodiment, and shows a magnetized state of a permanent magnet 410 of a rotor 400 according to a modification.

Embodiment 1 FIG.
1 to 14 are diagrams showing the first embodiment. FIG. 1 is a cross-sectional view of a synchronous motor 100 having 12 slots and 10 poles, FIG. 2 is a connection diagram of stator windings of the synchronous motor 100, and FIG. FIG. 4 is a cross-sectional view of the rotor 200 of the synchronous motor 100, FIG. 5 is a diagram showing the magnetized state of the permanent magnet 210 of the rotor 200, FIG. FIG. 7 is a diagram showing an example of a surface magnetic flux density distribution waveform of the rotor 200 of FIG. 5, and FIG. 7 is an induced voltage waveform of the 12-slot 10-pole synchronous motor 100 using the rotor 200 of FIG. FIG. 8 is a diagram comparing the induced voltage waveforms of the synchronous motor 500. FIG. 8 shows the relationship between the flat portion angle of the magnetic pole center of the rotor surface magnetic flux density distribution and the induced voltage distortion rate. Slot 10 pole synchronous motor 10 FIG. 9 shows only the 12-slot 10 poles of FIG. 8, FIG. 10 shows the flat part angle of the magnetic pole center of the rotor surface magnetic flux density distribution, the rotor surface magnetic flux waveform, and the induced voltage. FIG. 11 is a diagram showing a relationship between the included primary components and a comparison between 12 slots and 8 poles and 12 slots and 10 poles. FIG. 11 shows a flat part angle of a magnetic pole center of a rotor surface magnetic flux density distribution waveform and a surface magnetic flux density. FIG. 12 is a diagram showing the relationship between the amplitude (crest value) of the distribution waveform and the ratio of the amplitude of the first-order component, and FIG. FIG. 13 is a diagram showing a relationship between components, FIG. 13 is a diagram showing a relationship between a fifth harmonic component included in the rotor surface magnetic flux waveform and a fifth harmonic component included in the induced voltage, and FIG. 14 is a rotor surface magnetic flux waveform. 7th order harmonic component and 7th order contained in induced voltage Is a diagram showing the relationship between the harmonic component.

  15 to 18 are diagrams for comparison, FIG. 15 is a cross-sectional view of a 12-slot 8-pole synchronous motor 500, and FIG. 16 is a connection diagram of a stator winding of the 12-slot 8-pole synchronous motor 500. FIG. 17 is a development view showing a method of connecting the stator windings of the synchronous motor 500 with 12 slots and 8 poles, and FIG. 18 is a cross-sectional view of the rotor 600 of the synchronous motor 500 with 12 slots and 8 poles.

  A synchronous motor 100 shown in FIG. 1 is a concentrated winding 12-slot 10-pole motor.

  The synchronous motor 500 shown for comparison in FIG. 15 is a 12-slot 8-pole motor that is also concentrated.

  The synchronous motor 100 or the like may be simply referred to as an electric motor.

  Both (synchronous motor 100 and synchronous motor 500) differ in the number of magnetic poles of the rotor. The rotor 200 of the synchronous motor 100 has ten permanent magnets 210 and has ten magnetic poles (see FIG. 4). On the other hand, the rotor 600 of the synchronous motor 500 has eight permanent magnets 610 and the number of magnetic poles is eight (see FIG. 18).

  The rotor 200 or the like may be simply referred to as a rotor.

  Both (synchronous motor 100 and synchronous motor 500) differ in the arrangement of the armature windings of the stator in addition to the number of magnetic poles of the rotor.

  The synchronous motor 500 having 12 slots and 8 poles is a general three-phase armature winding wound around the teeth of a stator. The number of windings (the same as the number of teeth, 12) And the ratio of the number of magnetic poles of the rotor (8 poles) is 3: 2.

  The stator windings are arranged in such a manner that the windings of the respective phases are arranged in the order of the U phase, the V phase, and the W phase, and an alternating current having a phase difference of 120 ° is supplied to each of the stator motor 500. Drive.

  This will be described in detail with reference to FIGS. Since the stator has 12 slots, the number of teeth formed between the slots (the space in which the winding is housed is called a slot) is also 12.

  Here, suppose that the U1 + coil (the coil to which the U terminal connected to the power source is connected) is wound with tooth # 1, and in order counterclockwise, # 1, # 2,. # 12 (see FIG. 15).

  The windings of each phase are connected in series, and the neutral point N forms a three-phase star connection. That is, the U-phase U1 + coil, U2 + coil, U3 + coil, and U4 + coil are connected in series. The U1 + coil is connected to a U terminal connected to a power source. The U4 + coil is connected to the neutral point N.

  The V-phase V1 + coil, V2 + coil, V3 + coil, and V4 + coil are connected in series. The V1 + coil is connected to a V terminal connected to a power source. The V4 + coil is connected to the neutral point N.

  Furthermore, the W phase W1 + coil, W2 + coil, W3 + coil, and W4 + coil are connected in series. The W1 + coil is connected to a V terminal connected to a power source. The W4 + coil is connected to the neutral point N.

  “+” Of U1 + represents the winding direction of the coil. For example, in the developed view of FIG. 17, the U1 + coil wound around the # 1 tooth is wound clockwise when viewed from the tip (see FIG. 17) side of the tooth. If the U1 coil wound around # 1 teeth is wound counterclockwise, it will be referred to as U1-coil.

  The arrangement and connection method of the stator windings of the synchronous motor 500 having 12 slots and 8 poles will be described with reference to a development view showing the connection method of the stator windings of FIG.

  In FIG. 17, the U1 + coil to which the U-phase power terminal (U terminal) is connected is wound around the rightmost # 1 tooth in the clockwise direction when viewed from the front end side of the tooth.

  A U2 + coil of the U phase is wound in a clockwise direction as viewed from the front end side of the teeth on # 4 teeth obtained by skipping two teeth (# 2 teeth, # 3 teeth) from # 1 teeth.

  The magnet wire between the U1 + coil and the U2 + coil is called a U-phase crossover.

  The U-phase U3 + coil is wound in the clockwise direction as viewed from the front end side of the teeth by # 7 teeth obtained by skipping two teeth (# 5 teeth and # 6 teeth) from # 4 teeth.

  The magnet wire between the U2 + coil and the U3 + coil is also called a U-phase crossover.

  The U-phase U4 + coil is wound clockwise from # 7 teeth to # 10 teeth in which two teeth (# 8 teeth, # 9 teeth) are blown, as viewed from the front end side of the teeth.

  The magnet wire between the U3 + coil and the U4 + coil is also called a U-phase crossover.

  The winding end of the U phase U4 + coil is connected to the neutral point N.

  In FIG. 17, the V1 + coil to which the V-phase power supply terminal (V terminal) is connected is wound clockwise around the second # 2 tooth from the right end as viewed from the tip end side of the tooth.

  The V-phase V2 + coil is wound clockwise from # 2 teeth to # 5 teeth obtained by skipping two teeth (# 3 teeth and # 4 teeth) as viewed from the front end side of the teeth.

  The magnet wire between the V1 + coil and the V2 + coil is called a V-phase crossover.

  The V-phase V3 + coil is wound clockwise from # 5 teeth to # 8 teeth from which two teeth (# 6 teeth, # 7 teeth) are blown, as viewed from the front end side of the teeth.

  A magnet wire between the V2 + coil and the V3 + coil is also called a V-phase crossover.

  The V-phase V4 + coil is wound in the clockwise direction when viewed from the tip end side of the teeth, to # 11 teeth obtained by skipping two teeth (# 9 teeth, # 10 teeth) from # 8 teeth.

  The magnet wire between the V3 + coil and the V4 + coil is also called a V-phase crossover.

  The winding end of the V4 + coil of the V phase is connected to the neutral point N.

  In FIG. 17, the W1 + coil to which the W-phase power supply terminal (W terminal) is connected is wound clockwise around the third # 3 tooth from the right end as viewed from the tip end side of the tooth.

  The W2 + coil of the W phase is wound clockwise from # 3 teeth to # 6 teeth where two teeth (# 4 teeth, # 5 teeth) are blown, as viewed from the front end side of the teeth.

  The magnet wire between the W1 + coil and the W2 + coil is called a W-phase crossover.

  The W3 + coil of the W phase is wound clockwise from # 6 teeth to # 9 teeth, which are two teeth (# 7 teeth, # 8 teeth), as viewed from the tip side of the teeth.

  The magnet wire between the W2 + coil and the W3 + coil is also called a W-phase crossover.

  The W4 + coil of the W phase is wound clockwise from # 9 teeth to # 12 teeth obtained by skipping two teeth (# 10 teeth and # 11 teeth) as viewed from the front end side of the teeth.

  The magnet wire between the W3 + coil and the W4 + coil is also called a W-phase crossover.

  The winding end of the W4 + coil of the W phase is connected to the neutral point N.

  The stator winding of the synchronous motor 500 having 12 slots and 8 poles is formed by, for example, the above arrangement and connection method.

  On the other hand, in the synchronous motor 100 with 12 slots and 10 poles, the winding is wound around each tooth in the same manner, but the arrangement of windings in each phase is different, and there are four coils in each phase. (Windings) are arranged side by side in pairs (for example, U1 + coil and U2-coil in FIG. 1).

  Further, a pair of adjacent coils (for example, U1 + coil and U2-coil in FIG. 1) are wound in opposite directions, and form different poles when current is applied (for example, FIG. 1). U1 + coil and U2- coil).

  As shown in FIG. 2, the coils of each phase are connected in series, and a neutral point N forms a three-phase star connection. That is, the U-phase U1 + coil, U2-coil, U3-coil, and U4 + coil are connected in series. The U1 + coil is connected to a U terminal connected to a power source. The U4 + coil is connected to the neutral point N.

  The V-phase V1-coil, V2 + coil, V3 + coil, and V4-coil are connected in series. The V1-coil is connected to a V terminal connected to a power source. The V4-coil is connected to the neutral point N.

  In addition, the W-phase W1 + coil, W2-coil, W3-coil, and W4 + coil are connected in series. The W1 + coil is connected to a V terminal connected to a power source. The W4 + coil is connected to the neutral point N.

  As already described, “+” of U1 + and “−” of U2- represent the winding direction of the coil. For example, if “+” is clockwise, “−” means counterclockwise. The winding direction of the coil is the winding direction from the power supply terminal to the neutral point.

  Here again, suppose that the U1 + coil (the coil to which the U terminal connected to the power supply is connected) is # 1, the teeth wound in # 1, # 2,. # 12 (see FIG. 1).

  The arrangement and connection method of the stator windings of the synchronous motor 100 will be described in detail with reference to a development view showing the connection method of the stator windings of the synchronous motor 100 with 12 slots and 10 poles in FIG.

  The U1 + coil to which the U-phase power supply terminal (U terminal) is connected is wound around the rightmost # 1 tooth in FIG. 3 in the clockwise direction when viewed from the front end side of the tooth.

  The U2-coil of the U phase is wound around the # 2 tooth adjacent to the # 1 tooth in the counterclockwise direction when viewed from the front end side of the tooth.

  The magnet wire between the U1 + coil and the U2- coil is called a U-phase crossover.

  The U-phase U3-coil is counterclockwise when viewed from the tip of the teeth to the # 7 teeth where four teeth (# 3 teeth, # 4 teeth, # 5 teeth, # 6 teeth) are blown from the # 2 teeth. Wound in the direction.

  The magnet wire between the U2-coil and the U3-coil is also called a U-phase crossover.

  The U4 + coil of the U phase is wound around the # 8 teeth adjacent to the # 7 teeth in the clockwise direction when viewed from the front end side of the teeth.

  The magnet wire between the U3-coil and the U4 + coil is also called a U-phase crossover.

  The winding end of the U phase U4 + coil is connected to the neutral point N.

  In FIG. 3, the V1-coil to which the V-phase power supply terminal (V terminal) is connected is wound around the third # 3 tooth from the right end in the counterclockwise direction when viewed from the front end side of the tooth.

  The V2 + coil of V phase is wound around the # 4 teeth adjacent to the # 3 teeth in the clockwise direction when viewed from the front end side of the teeth.

  The magnet wire between the V1-coil and the V2 + coil is called a V-phase crossover.

  The V3 + coil of V-phase is clockwise from the tip of the teeth to the # 9 teeth where four teeth (# 5 teeth, # 6 teeth, # 7 teeth, # 8 teeth) are blown from the # 4 teeth. It is rolled up.

  A magnet wire between the V2 + coil and the V3 + coil is also called a V-phase crossover.

  The V4-coil of the V phase is wound around the # 10 teeth adjacent to the # 9 teeth in the counterclockwise direction when viewed from the front end side of the teeth.

  The magnet wire between the V3 + coil and the V4- coil is also called a V-phase crossover.

  The winding end of the V-phase V4-coil is connected to the neutral point N.

  A W1 + coil to which a W-phase power supply terminal (W terminal) is connected is wound clockwise around the fifth # 5 tooth from the right end in FIG. 3 when viewed from the tip end side of the tooth.

  The W2-coil of the W phase is wound around # 6 teeth adjacent to the # 5 teeth in the counterclockwise direction when viewed from the front end side of the teeth.

  The magnet wire between the W1 + coil and the W2- coil is called a W-phase crossover.

The W3-coil of the W phase is counterclockwise as viewed from the tip of the teeth to the # 11 teeth where four teeth (# 7 teeth, # 8 teeth, # 9 teeth, # 10 teeth) are blown from the # 6 teeth. Wound in the direction.
It is burned.

  A magnet wire between the W2-coil and the W3-coil is also called a W-phase crossover.

  The W4 + coil of the W phase is wound around the # 12 tooth adjacent to the # 11 tooth in the clockwise direction when viewed from the tip end side of the tooth.

  The magnet wire between the W3-coil and the W4 + coil is also called a W-phase crossover.

  The winding end of the W4 + coil of the W phase is connected to the neutral point N.

  The stator winding of the synchronous motor 100 having 12 slots and 10 poles is formed by, for example, the above arrangement and connection method.

  The shape of the rotor 200 of the synchronous motor 100 in the present embodiment is, for example, as shown in FIG. A permanent magnet 210 constituting a 10-pole magnetic pole is disposed on the rotor surface.

  The permanent magnet 210 is fixed to the surface of the back yoke 230 by, for example, adhesion.

  In this example, the permanent magnet 210 has a uniform thickness in the radial direction. The shape of the permanent magnet 210 may be a cylindrical shape or a configuration using a plurality of tile-shaped (arc-shaped) permanent magnets.

  In the following description, in the case of general theory, it is simply referred to as “permanent magnet” and is not labeled.

  The shape of the rotor 600 of the 12-slot 8-pole synchronous motor 100 is, for example, as shown in FIG.

  The rotor 200 shown in FIG. 4 has a shape that most easily represents the characteristics of the present embodiment, and is therefore taken as a representative example, and is limited to this as long as the characteristics of the present invention can be realized. Is not to be done.

  In order to show the effect of the present embodiment, a magnetized state as shown in FIG. 5 is assumed as a characteristic of the permanent magnet 210 of the rotor 200 of FIG.

  That is, the magnetized state of the permanent magnet 210 constituting one magnetic pole is radial magnetized radially with respect to the rotating shaft 220 (see FIG. 4) of the rotor 200, and the vicinity of the magnetic pole center is completely magnetized. The magnetization amount is linearly changed (decreased) with respect to the state and the boundary (between poles) between adjacent magnetic poles, and the magnetization state is set to a trapezoidal wave shape.

  The surface magnetic flux density distribution waveform of the rotor 200 in which the permanent magnet 210 set in such a magnetized state (trapezoidal wave shape) is arranged is as shown in FIG.

  This is a simulation of the state incorporated in the synchronous motor 100, and the magnetic flux density in the air gap when the rotor 200 is installed through the air gap inside the cylindrical space equivalent to the inner diameter of the stator of the synchronous motor 100. It is obtained by electromagnetic field analysis of the distribution.

  As shown in FIG. 6, since the permanent magnet 210 is magnetized in a trapezoidal shape, the surface magnetic flux density is flat in the vicinity of the magnetic pole center.

  The magnetized state of the permanent magnet 210 is trapezoidal, but the magnetic flux density distribution waveform in the gap between the outer magnetic body (stator core) is slightly smoother and has a trapezoidal corner. Become.

  The magnetic flux density distribution waveform shown in FIG. 6 is an example in which the flat portion is about 120 ° when the width of the portion having a value up to 95% of the maximum value (crest value) of the magnetic flux density is defined as “flat portion”. is there.

  FIG. 7 shows the induced voltage when the rotor having the magnetized permanent magnet of FIG. 5 is incorporated in the synchronous motor. The synchronous motor 100 with 12 slots and 10 poles and the synchronous motor 500 with 12 slots and 8 poles are shown. And comparing. In both the 12-slot 10-pole synchronous motor 100 and the 12-slot 8-pole synchronous motor 500, the magnetized state of the permanent magnet is trapezoidal.

  The surface magnetic flux density distribution of the rotor is trapezoidal, and the distortion is larger than that of a sine wave. Therefore, the induced voltage is also easily distorted. In the synchronous motor 500 having 12 slots and 8 poles, the waveform of the induced voltage is distorted and trapezoidal. The waveform is close to a wave shape.

  On the other hand, in the case of the synchronous motor 100 with 12 slots and 10 poles, the waveform is close to a sine wave. Therefore, the 12-slot, 10-pole synchronous motor 100 has a feature that even if the magnetic flux density distribution on the rotor surface contains a large amount of distortion, the induced voltage is hardly distorted. It can be seen that the synchronous motor 100 is low noise.

  FIG. 8 shows the result of a comparison between the synchronous motor 500 having 12 slots and 8 poles and the synchronous motor 100 having 12 slots and 10 poles with respect to the relationship between the flat portion angle at the magnetic pole center of the rotor surface magnetic flux density distribution and the induced voltage distortion rate. Show. There is a tendency for the distortion of the induced voltage to decrease by reducing the width of the flat portion, but the distortion rate of the synchronous motor 100 with 12 slots and 10 poles is lower than that of the synchronous motor 500 with 12 slots and 8 poles. ing.

  The induced voltage distortion rate is a total harmonic distortion rate (THD (Total Harmonic Distortion)).

  FIG. 9 shows only the characteristics of the synchronous motor 100 having 12 slots and 10 poles. From this characteristic, the induced voltage distortion rate can be made less than 1% by setting the width (flat portion angle) of the flat portion near the magnetic pole center to 125 ° or less.

  FIG. 10 shows a 12-slot 8-pole synchronous motor 500 and a 12-slot 10-pole primary component of the induced voltage with the width of the flat part of the magnetic pole center of the rotor surface magnetic flux density distribution (see FIG. 6) as a parameter. A comparison with the synchronous motor 100 is shown. It can be seen that as the width of the flat portion is reduced, the primary component included in the induced voltage is reduced.

  When the width of the flat portion is the same, the synchronous motor 100 with 12 slots and 10 poles includes a larger primary component in the induced voltage than the synchronous motor 500 with 12 slots and 8 poles. The slot 10 pole can output a larger torque.

  In other words, the 12-slot, 10-pole synchronous motor 100 can be said to be an electric motor with less copper loss because the current required to output the same torque is reduced.

  FIG. 11 shows the relationship between the flat part angle (see FIG. 6) of the magnetic pole center of the rotor surface magnetic flux density distribution waveform, the amplitude (crest value) of the surface magnetic flux density distribution waveform, and the ratio of the amplitude of the primary component. Is. On the vertical axis, a value indicating the ratio of the amplitude (crest value) of the surface magnetic flux density distribution waveform to the amplitude of the primary component is taken, and the larger this value, the larger the primary component contained in the waveform. ing.

  The horizontal axis of FIG. 11 is the flat portion angle [deg] of the surface magnetic flux density waveform.

  From FIG. 11, if the flat part angle (width) of the surface magnetic flux density waveform is 45 ° (electrical angle) or more, a primary component larger than the amplitude of the surface magnetic flux density distribution waveform is included.

  Since the surface magnetic flux density of the rotor is determined by the thickness of the permanent magnet, if the thickness is constant like the permanent magnet 210 (see FIG. 5) of the rotor 200 handled in the present embodiment, the flat portion angle Since the amplitude is constant regardless of the (width) size, if the flat part angle (width) is 45 ° or more, a larger primary component can be obtained even if permanent magnets of the same thickness are used, and the induced voltage is also reduced. A larger primary component can be included, and the synchronous motor 100 having a larger torque or higher efficiency can be realized.

  FIG. 12 shows the relationship between the harmonic component included in the surface magnetic flux density distribution waveform of the rotor and the flat portion angle of the waveform. The surface magnetic flux density distribution waveform of the rotor is a trapezoidal waveform. The harmonic components contained in are many third-order components, followed by many fifth-order, seventh-order, and ninth-order components.

  As the flat portion angle (width) of the magnetic flux density distribution waveform becomes smaller, the waveform becomes closer to a sine wave, so that the contained harmonic components decrease.

  If it is combined with FIG. 11, if the flat part angle (width) is widened, the primary component contained therein will increase, but harmonic components such as the 3rd, 5th, 7th and 9th will also increase accordingly. To increase. Harmonic components of odd multiples of 3 such as 3rd order and 9th order cancel each other in the three-phase windings and are not included in the induced voltage, but other harmonics appear in the induced voltage. Causes waveform distortion.

  FIG. 13 shows the relationship between the fifth order component included in the surface magnetic flux density distribution waveform of the rotor and the fifth order component included in the induced voltage. In the synchronous motor 500 having 12 slots and 8 poles, the fifth-order component is included in the waveform of the induced voltage at almost the same ratio as the fifth-order component included in the surface magnetic flux density distribution waveform of the rotor 600. In the synchronous motor 100 having 12 slots and 10 poles, the ratio of the fifth-order component generated in the induced voltage is very small compared to the ratio of the fifth-order component included in the surface magnetic flux density distribution waveform.

  FIG. 14 shows the relationship between the seventh-order component included in the rotor surface magnetic flux density distribution waveform and the seventh-order component included in the induced voltage. In 12-slot 8-pole synchronous motor 500, the seventh-order component is included in the waveform of the induced voltage more than the ratio of the seventh-order component included in the surface magnetic flux density distribution waveform of rotor 600. On the other hand, in the synchronous motor 100 with 12 slots and 10 poles, the ratio of the seventh-order component generated in the induced voltage to the ratio of the seventh-order component included in the surface magnetic flux density distribution waveform is the fifth-order component shown in FIG. Although it is large compared with the characteristics related to, the effect is small.

  This characteristic indicates that even if the surface magnetic flux density distortion of the rotor 200 is large in the synchronous motor 100 having 12 slots and 10 poles, the distortion of the induced voltage waveform is small. In the 12-slot 10-pole synchronous motor 100 having a larger torque that can be output at the same current than the pole, the waveform of the surface magnetic flux density distribution of the rotor 200 is trapezoidal, and the width of the flat portion at the center of the magnetic pole is 45 ° or more Thus, it is possible to output a larger torque than the advantage obtained by the difference in winding coefficient, and further, by setting the width of the flat portion at the center of the magnetic pole to 125 ° or less, distortion of the induced voltage can be suppressed to a small value.

Embodiment 2. FIG.
19 to 22 are diagrams showing the second embodiment. FIG. 19 is a cross-sectional view of the rotor 300. FIG. 20 is a diagram showing a magnetized state of the permanent magnet 310 of the rotor 300. FIG. FIG. 22 is a diagram showing a magnetized state of the permanent magnet 410 of the rotor 400 according to a modification.

  The rotor 300 of the synchronous motor shown in FIG. 19 has a form in which a permanent magnet 310 is disposed on the rotor surface, and the inner side of the permanent magnet 310 is made of a magnetic material that serves as a back yoke 330 of the permanent magnet. In addition, a rotation shaft 320 is provided at a substantially central portion of the rotor 300.

  In the rotor 300 shown in FIG. 19, the shape of the permanent magnet 310 constituting one magnetic pole is a uniform thickness near the center of the magnetic pole, and the thickness near the magnetic pole is smaller than the thickness near the center of the magnetic pole. (See FIG. 20).

  The permanent magnet 310 has a circular outer periphery. And the thickness between the magnetic poles of the inner periphery of the permanent magnet 310 is made concave so that the thickness near the magnetic poles is reduced.

  In the portion where the thickness of the permanent magnet 310 is uniform, the magnetic flux density distribution on the surface is constant.

  When the thickness of the permanent magnet 310 is reduced at both ends of the magnetic pole (between the poles), the magnetic flux density on the rotor surface at that portion is reduced.

  Therefore, a trapezoidal distribution waveform in which the magnetic flux density distribution on the surface of the rotor is flat in the vicinity of the magnetic pole center can also be realized by forming a permanent magnet 310 like the rotor 300 shown in FIG.

  In the rotor 300 shown in FIG. 19, the magnetic flux density distribution waveform on the rotor surface is formed by the thickness of the permanent magnet 310, and the magnetized state of each part of the permanent magnet 310 can be almost completely magnetized. Therefore, irreversible demagnetization due to the magnetic flux on the armature (stator) side is unlikely to occur, and deterioration of the characteristics of the synchronous motor can be suppressed.

  When the shape of the permanent magnet 310 is a ring shape as in the rotor 300 shown in FIG. 19, it is necessary to match the shape of the outer periphery of the back yoke 330 and the inner diameter shape of the permanent magnet 310. Assembling and fixing other parts by bonding or the like may deteriorate the workability. In this case, workability can be improved by making the permanent magnet 310 a bond magnet having a relatively high degree of freedom in shape.

  Also, productivity can be improved by integrally molding the permanent magnet 310 with the back yoke 330.

  Further, when the back yoke 330 is made of a steel material such as an electromagnetic steel plate, the permanent magnet 310 may be cracked due to a temperature change in the usage environment due to a difference in linear expansion coefficient from the bonded magnet. It becomes difficult to reduce the wall thickness.

  In the case of using an expensive rare earth permanent magnet, the magnet thickness is often reduced to reduce the amount of use, and the conditions are more severe with respect to changes in the usage environment.

  On the other hand, it is possible to prevent the permanent magnet 310 from cracking by configuring the back yoke 330 with a resin material mixed with magnetic powder (an example of a magnetic material) and bringing the coefficients of linear expansion close to each other. .

  A modified rotor 400 will be described with reference to FIGS. The rotor 400 of the modification also has a permanent magnet 410 disposed on the rotor surface, and a magnetic back yoke 430 is disposed inside. A rotating shaft 320 is provided at substantially the center of the rotor 400.

  The shape of the permanent magnet 410 constituting one magnetic pole is an arc shape with a uniform magnet thickness near the magnetic pole center.

  The permanent magnet 410 becomes thinner as it gets closer to the gap between the magnetic poles, and the outer circumference of the rotor becomes smaller. In other words, the permanent magnet 410 has a shape with a depression on the outer circumference of the rotor (configured with separate permanent magnets for each magnetic pole). In the case, the shape is cut on both sides).

  Near the center of the magnetic pole, the permanent magnet 410 has a uniform thickness and air gap, so that the magnetic flux density on the rotor surface is the same.

  When approaching between the magnetic poles, the thickness of the permanent magnet 410 is thin, the air gap (the space between the armature (stator) and the rotor) becomes wider, and the magnetic flux density on the surface gradually decreases. As a result, the surface magnetic flux density distribution waveform of the rotor 400 is flat near the center of the magnetic pole and has a shape like a trapezoidal wave.

  That is, the permanent magnet 310 has a circular inner periphery. And the thickness between the magnetic poles of the outer periphery of the permanent magnet 310 is made concave so that the thickness near the magnetic poles is reduced.

  In this shape, the outer peripheral shape of the back yoke 430 and the inner peripheral shape of the permanent magnet 410 are circular, so that the workability and assemblability are relatively good.

  Although the 12-slot 10-pole synchronous motor has been described above, the 12n-slot 10n-pole (n is a natural number) including the 12-slot 10-pole is the target of this embodiment.

  As an application example of the present invention, application to a synchronous motor used in a blower is possible.

  100 synchronous motor, 200 rotor, 210 permanent magnet, 220 rotating shaft, 230 back yoke, 300 rotor, 310 permanent magnet, 320 rotating shaft, 330 back yoke, 400 rotor, 410 permanent magnet, 420 rotating shaft, 430 back Yoke, 500 synchronous motor, 600 rotor, 610 permanent magnet.

Claims (10)

In the rotor of a three-phase 12n slot 10n pole (n is a natural number) synchronous motor,
The magnetic flux density distribution on the rotor surface is a waveform in which the vicinity of the magnetic pole center is flat, and the magnetic flux density decreases from this flat part toward the poles.
The circumferential width of the flat portion near the magnetic pole center is set to 45 ° to 125 ° in electrical angle ,
By setting the circumferential width of the flat portion near the magnetic pole center to 45 ° or more in electrical angle, the amplitude of the primary component included in the induced voltage is made larger than the amplitude of the magnetic flux density distribution waveform on the rotor surface. ,
The synchronous motor rotor , wherein the induced voltage distortion rate is less than 1% by setting the circumferential width of the flat portion near the magnetic pole center to be 125 ° or less in electrical angle .   A permanent magnet is disposed on the surface of the rotor, and the thickness of the permanent magnet is substantially uniform over the entire magnetic pole. By magnetization, the magnetic flux density distribution on the surface of the rotor is flat and the vicinity of the center of the magnetic pole is flat and between the poles. 2. The rotor of a synchronous motor according to claim 1, wherein the magnetic flux density is reduced to a waveform.   A permanent magnet is disposed on the rotor surface, and the thickness of the permanent magnet is uniform near the center of the magnetic pole, and the thickness near the boundary between adjacent magnetic poles is thinner than the vicinity of the magnetic pole center. The rotor of the synchronous motor according to claim 1.   The synchronous motor rotor according to claim 3, wherein the permanent magnet has a circular outer periphery and a concave shape in the vicinity of the inner peripheral magnetic pole.   4. The rotor of a synchronous motor according to claim 3, wherein the permanent magnet has a circular inner periphery and a concave portion between the outer peripheral magnetic poles.   6. The synchronous motor rotor according to claim 2, wherein a rare earth permanent magnet is used as the permanent magnet.   The synchronous motor rotor according to claim 2, wherein a bonded magnet is used as the permanent magnet.   The synchronous motor rotor according to any one of claims 2 to 7, wherein the permanent magnet includes a back yoke provided on a surface thereof, and the back yoke is made of a resin material containing a magnetic material.   The synchronous motor rotor according to claim 8, wherein the permanent magnet is formed integrally with the back yoke. A synchronous motor using the rotor of the synchronous motor according to claim 1.

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