JP2018007313A - Permanent magnet motor and elevator driving/hoisting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet motor at as low cost as possible by reducing the content of dysprosium in a neodymium rare earth magnet for forming a rotor or keeping the magnet from including dysprosium.SOLUTION: A permanent magnet motor comprises: a rotor using an electromagnetic steel plate and a neodymium rare earth magnet; and a stator using an electromagnetic steel plate. According to a content of dysprosium in the neodymium rare earth magnet included in the rotor, and an iron loss of the electromagnetic steel plates of the rotor and stator, the thickness of the neodymium rare earth magnet of the rotor in a radial direction is determined to be a thickness that never causes the demagnetization of the neodymium rare earth magnet.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a permanent magnet motor and an elevator drive hoist using the same.

  The motor for the elevator drive hoisting machine is desirably installed in the hoistway without a dedicated machine room from the viewpoint of improving the flexibility of the building layout. The hoistway is not airtight due to its structure, and dust and dust enter it. Dust and dust entering the sliding surface of the motor, etc., can cause a failure. From the viewpoint of improving reliability and reducing the maintenance burden, the elevator motor installed in the hoistway is attached to the motor itself. It is necessary to have a fully closed structure with airtightness.

  Permanent magnet motors with high torque density and low torque pulsation are used for elevator-driven hoisting machines that require small size, light weight, and low vibration. For this motor, a neodymium magnet having a high energy density is generally employed. Although the coercive force of a neodymium magnet decreases as the temperature rises, copper loss, iron loss, etc. occur when the motor is driven, and heat is generated, so that the motor becomes hot and there is a high risk that the magnet will demagnetize. The demagnetization of the motor magnets should change the behavior of the elevator and not endanger passengers. Further, when the magnet is partially demagnetized, torque pulsation is deteriorated, vibration and noise are increased, and there is a possibility that passengers may feel uncomfortable. Therefore, in an elevator motor, the demagnetization factor of the magnet must be 0%. As a measure for lowering the motor temperature, in order to increase the efficiency of cooling the motor by air cooling, an open structure in which an opening for taking in air into the motor is provided in the motor can be considered. In order to install the motor for the upper machine in the hoistway, it is necessary to have a fully closed structure. In addition, it is conceivable to provide a pipe for flowing water to the motor and cool it by water cooling. However, it is difficult to provide a water pipe for supplying water for water cooling in the hoistway in terms of structure and cost. .

By the way, an SPM (surface magnet type) motor is often used as a motor for an elevator drive hoist. Since there is no leakage between the permanent magnet and the stator winding, the SPM motor can effectively link the magnetic flux. Further, since the magnetic flux distribution in the gap does not contain many harmonics, it is suitable for a motor for an elevator drive hoisting machine that requires less vibration and noise and requires comfort. With respect to the SPM motor, the magnet may be damaged or the adhesive may be peeled off due to centrifugal force during high-speed rotation. However, the rotational speed of the motor for elevator-driven hoisting machines is approximately 160 min ^-1 for motors used mainly in condominiums and stations, and 260 min for motors used mainly in high-rise buildings and large-scale commercial facilities. Such a problem does not occur at a low speed of about ^-1 . On the other hand, on the gap surface of the rotor, the magnetic flux direction changes greatly due to the rotating magnetic field generated by the stator, and in the SPM motor in which the permanent magnet is arranged on the surface of the gap surface, the permanent magnet is likely to be demagnetized. In addition, since an open slot having no flange at the end of the stator teeth can reduce the number of winding work steps and simplify the winding equipment, it is a desirable structure for reducing the manufacturing cost. However, in the open slot structure, the change in magnetic flux at the tip of the tooth becomes steep, which leads to an increase in the harmonic component of the magnetic flux, and thus the iron loss increases. The greater the iron loss, the higher the magnet temperature, and the magnet is more likely to demagnetize.

  In order to maintain the coercive force even at a high temperature, dysprosium (Dy) is added to the neodymium magnet, but Dy is a rare rare earth resource and is very expensive. In addition, there is a risk that prices will soar due to limited production. From the viewpoint of cost, it is desirable to reduce the amount of Dy used as much as possible. However, as the Dy content in the magnet decreases, the coercive force of the magnet decreases.

  As means for improving the demagnetization resistance while reducing the amount of Dy used as much as possible, it is conceivable to increase the number of poles or increase the thickness of the magnet. For example, in Patent Document 1, by defining the Dy content necessary for securing the demagnetization proof strength for each of the three types of poles of 6 poles, 8 poles, and 10 poles, The amount of Dy used is reduced as much as possible to reduce the cost. This is because the magnetomotive force per stator coil can be reduced by increasing the number of poles under the same driving conditions, and the demagnetizing magnetic field received by the magnet is also reduced by this magnetomotive force. This is because it becomes difficult to magnetize. When 6 poles are 8 poles, the magnetomotive force per stator coil can be 2/3, and when 6 poles are 10 poles, the magnetomotive force per stator coil can be 3/5. As the magnetomotive force is reduced, the demagnetization resistance can be increased, so that the Dy content can be reduced as the number of poles is increased.

Japanese Patent No. 5661903

  As mentioned above, the motor for an elevator drive hoist must be designed so that the magnet is not demagnetized from the viewpoint of passenger safety and comfort. The structured motor is hot and easily demagnetized. In addition, an increase in iron loss due to the open slot structure also causes an increase in magnet temperature. In order to ensure the coercive force at high temperature, it is necessary to use a magnet having a large Dy content, which causes an increase in motor cost.

  In Patent Document 1, in three types of poles of 6 poles, 8 poles, and 10 poles, Dy content necessary for securing the demagnetization proof strength is defined for each pole number, so that Dy is as much as possible The amount of use is reduced and the cost is reduced. However, creating and using magnets having different Dy contents for each number of poles is inefficient in terms of mass productivity and may increase costs. In addition, as described above, even if the Dy content is the same, the coercive force should be different depending on the manufacturing method and composition, but this patent does not know how much coercive magnet is assumed. .

  An object of the present invention is to provide a permanent magnet motor that can reduce the cost as much as possible by reducing or not including the dysprosium content in the neodymium rare earth magnet constituting the rotor.

  The above problem is that the heat generated by iron loss changes depending on the electromagnetic steel sheet used in the motor, the magnet temperature changes and the coercive force changes, and the coercive force changes depending on the Dy content of the neodymium rare earth magnet used in the motor. Therefore, it can be solved by defining the minimum magnet thickness that can maintain the demagnetization resistance.

If an example of the “permanent magnet motor” of the present invention is given,
A permanent magnet motor comprising a rotor using an electromagnetic steel sheet and a neodymium rare earth magnet, and a stator using an electromagnetic steel sheet,
According to the dysprosium content in the neodymium rare earth magnet constituting the rotor and the iron loss amount of the rotor and stator electromagnetic steel sheet, the thickness of the neodymium rare earth magnet in the rotor is set to the radial thickness of the neodymium rare earth magnet. A permanent magnet motor having a thickness that does not cause demagnetization of the magnet.

  According to the present invention, by defining the thickness of the rotor magnet in the radial direction in accordance with the dysprosium content in the neodymium rare earth magnet constituting the rotor and the iron loss amount of the electromagnetic steel plate of the rotor and stator. Thus, it is possible to provide a permanent magnet motor whose cost is suppressed as much as possible.

It is a figure which shows the relationship between the BH demagnetization curve of a neodymium magnet, and a permeance straight line (at the time of no load). It is a figure which shows the relationship between the BH demagnetization curve of a neodymium magnet, and a permeance straight line (at the time of load). It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate used for a motor, and the magnet temperature of a heat saturation state. It is a figure which shows an example of the cross-sectional shape of the 40 pole 48 slot permanent magnet motor of Example 1. FIG. It is a figure which shows the relationship between the magnet thickness of Example 1, and a demagnetizing factor. It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate of Example 1, and magnet thickness. It is a figure which shows an example of the cross-sectional shape of the 50 pole 60 slot permanent magnet motor of Example 2. FIG. It is a figure which shows the relationship between the magnet thickness of Example 2, and a demagnetization factor. It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate of Example 2, and magnet thickness. FIG. 6 is a diagram illustrating an example of a cross-sectional shape of a 60-pole 72-slot permanent magnet motor according to a third embodiment. It is a figure which shows the relationship between the magnet thickness of Example 3, and a demagnetizing factor. It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate of Example 3, and magnet thickness. It is a figure which shows the relationship between the magnet thickness of Example 4, and a demagnetizing factor. It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate of Example 4, and magnet thickness. It is a figure which shows the relationship between the magnet thickness of Example 5, and a demagnetizing factor. It is a figure which shows the relationship between the iron loss of the electromagnetic steel plate of Example 5, and magnet thickness.

  From the viewpoint of mass productivity, it is considered better to improve the demagnetization resistance by adjusting the thickness of the magnet using the same Dy content. However, by increasing the magnet thickness, a magnet having a small Dy content can be used. However, increasing the amount of magnet used may cause the amount of Dy used to remain unchanged, which is problematic in terms of cost. Moreover, although it is cheaper than Dy, neodymium (Nd) used for a neodymium magnet is also a rare earth and is expensive, and the production area is limited. It is desirable that the magnet be as thin as possible. The limit magnet thickness that can maintain the demagnetization resistance will be described below.

Figure 1 incorporating the motor and B-H demagnetization curve 1 of magnet temperature C neodymium magnet, and B-H demagnetization curve 2 of magnet temperature D, permeance linear 3 and magnet thickness of the magnet thickness Y ₁ It shows the permeance linear 4 Y _2. The magnet temperatures C and D are in a relationship of C <D. As shown in FIG. 1, in the neodymium magnet, as the magnet temperature increases, the residual magnetic flux density Br and the coercive force H _cb decrease. Permeance is the slope of the straight line permeance coefficient is a coefficient determined by the shape of the magnet, the magnet thickness of the magnet thickness Y ₁ and Y ₂ are in a relationship of Y 1 _{<Y 2.} The intersection of the permeance line and the BH demagnetization curve is an operating point indicating the magnetic flux density and magnetic field of the magnet in the magnetic circuit. When the operating point exceeds a certain limit, the magnet causes irreversible demagnetization. The knick point 5 indicates this limit. FIG. 1 shows an operating point 6 at no load. If the thickness of the magnet is Y _1, it can be said that the operating point 6 does not exceed the knick point 5 and does not undergo irreversible demagnetization at any of the magnet temperatures C and D in an unloaded state. Further, even if the magnet thickness is Y ₂ , in an unloaded state, the operating point 6 does not exceed the knick point 5 and does not undergo irreversible demagnetization regardless of the magnet temperature C or D. It can be said.

FIG. 2 shows an operating point under load in which a load is applied to the driven motor and a negative magnetic field is applied to the magnetization direction of the magnet. Since the negative magnetic field is applied, the permeance line moves in parallel, and the operating point that is the intersection with the BH curve also moves. When the magnet thickness is Y ₁ , if the magnet temperature is C, the operating point 7 does not exceed the knick point 5, but if the magnet temperature is D, the operating point 8 exceeds the knick point 5. ing. Once the operating point exceeds the knick point 5, even if the application of the negative magnetic field is stopped thereafter, the operating point at no load does not return to the original position. That is, when the thickness of the magnet is subjected to load by driving the motor of Y _1, but the magnet temperature is not irreversible demagnetization if is C, magnet temperature resulting in irreversible demagnetization if D. On the other hand, if the Y ₂ thickness of the magnet, even when the load, the operating point 9 of the magnet temperature C, and any operating point 10 of the magnet temperature D also does not exceed the knick point 5, the irreversible demagnetization It can be said that it does not. Here, when the magnet temperature in the magnet thickness Y ₂ is and D, since the operating point 10 and the knick point 5 overlap, when the magnet temperature and D, can be said to be a magnet thickness of the limits not to demagnetization. When the magnet temperature is D in the magnet thickness Y _1, the operating point 8 and knick points do not overlap, so that the operating point moves to the negative magnetic field side, there is room for thin magnet thickness. When the magnet temperature is C in the magnet thickness Y _1, can be reduced further magnet thickness to the magnet temperature than when the D.

  From the foregoing, it can be seen that the limit magnet thickness that does not perform irreversible demagnetization, that is, maintains the demagnetization resistance, varies depending on the magnet temperature. In a motor installed in a room temperature environment such as an elevator motor, the magnet temperature is determined by the heat generated by the motor itself. The heat generated by the motor itself is mainly copper loss and iron loss. Of these, the copper loss does not change significantly if the driving conditions do not change with the same number of coil turns and motor thickness, and the motor heat generation due to copper loss does not change. On the other hand, the iron loss that occurs when the motor is driven includes hysteresis loss and eddy current loss. The rotor and stator of the motor are composed of laminated steel sheets laminated with thin magnetic steel sheets of about 0.3 mm to 0.5 mm. The magnitudes of hysteresis loss and eddy current loss are the same driving conditions. However, it varies depending on the magnetic permeability, conductivity, plate thickness, and the like of the laminated steel plate. For example, 35A210, 50A600, and 50A1000 may be used as the electromagnetic steel plate. For these, the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T is defined as an electrical steel sheet defined as 2.1 W / kg or less for 35A210, 6.0 W / kg or less for 50A600, and 10.0 W / kg or less for 50A1000. Since the magnetic permeability, conductivity, and plate thickness are different as described above, the magnitude of the iron loss is different. Under the same driving conditions, the iron loss increases in the order of 35A210 <50A600 <50A1000. When the magnitude of the iron loss at the time of driving the motor is different, the heat generation due to the iron loss is also different, and the magnet temperature changes due to the influence of the heat generation.

  FIG. 3 shows the relationship between the electromagnetic steel sheet used for the motor and the magnet temperature when the motor using the electromagnetic steel sheet is driven to reach a thermal saturation state. The vertical axis represents the magnet temperature, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. It can be seen that the magnet temperature can be reduced as the motor uses a magnetic steel sheet having a smaller iron loss.

  From the viewpoint of reducing the cost of neodymium magnets, it is desirable to reduce the amount of magnets used as much as possible, and for that purpose, it is effective to reduce the magnet thickness. Furthermore, in order to ensure the demagnetization resistance even if the magnet is thinned, it is only necessary to select an electromagnetic steel sheet that reduces the iron loss. As for electrical steel sheets, the lower the iron loss, the higher the cost because of difficulty in manufacturing and the like, leading to an increase in cost. However, the main components of electrical steel sheets are iron (Fe) and silicon (Si), and these materials are more abundant on the earth than Nd and Dy used in neodymium magnets, so procurement is easy. And very inexpensive. Therefore, the price of electrical steel sheets is less likely to increase due to the procurement risk of materials compared to neodymium magnets. By increasing the thickness of the neodymium magnet when the price of the neodymium magnet is low, it is possible to maintain the demagnetization resistance even if the magnet temperature increases, using an inexpensive steel sheet with high iron loss. When the price of neodymium magnets soars, demagnetization resistance can be ensured by thinning the magnets in order to reduce the amount of magnets used and lowering the magnet temperature by using an expensive steel sheet with low iron loss. By responding to the cost fluctuation of the neodymium magnet by changing the electromagnetic steel sheet, it can be said that the increase in the cost of the motor can be reduced and the supply can be stably performed.

An embodiment using a neodymium rare earth magnet containing iron, neodymium, and boron but not containing dysprosium will be described. As this magnet, a magnet having a room-temperature coercive force of about H _cb = 1040 kA / m is assumed.

  As a first embodiment, application to a 40-pole 48-slot motor will be described. FIG. 4 is a sectional view of a 40 pole 48 slot electric motor. The permanent magnet 15 of this motor is a rare earth magnet that does not contain dysprosium. This motor is an abduction type (outer rotor type) motor in which the rotor 11 is rotatably disposed outside the stator 13. The rotor 11 is composed of a rotor core 12 and 40 permanent magnets 15, and the stator 13 is composed of a stator core 14 and 48 coils 17 wound around 48 teeth 16. Yes. The rotor core 12 and the stator core 14 are constituted by laminated steel plates in which electromagnetic steel plates are laminated.

FIG. 5 shows the relationship between the magnet thickness and the demagnetization factor for each electromagnetic steel sheet under the same driving conditions. Here, reduced permeability, E ₀ the induced voltage before supplying a demagnetizing current, the induced voltage after a current of demagnetizing current as E _1, from the equation _{(E 0 -E 1) / E} 0 × 100 This is the calculated value. It can be seen that the smaller the iron loss, the lower the magnet temperature.

FIG. 6 shows the relationship between the limit magnet thickness when the demagnetization factor is 0% and the electromagnetic steel sheet. The vertical axis represents the magnet thickness, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. As shown in FIG. 6, in a 40 pole 48 slot motor using a neodymium rare earth magnet containing iron, neodymium, and boron but not containing dysprosium, the maximum magnetic flux density is 1 at a frequency of 50 Hz of the electrical steel sheet used for the rotor and stator. When the iron loss at 5T is X, and the magnet thickness is Y,
Y ≧ 0.22X + 4.3
If so, the demagnetization rate can be reduced to 0%. Here, from the viewpoint of the magnet thickness at which the demagnetization factor is 0% in consideration of the demagnetization resistance, the lower limit of the magnet thickness may be determined. However, the thicker the magnet thickness, the higher the cost. From the difference in cost between a magnet with a Dy content of 0% and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
0.22X + 5.2 ≧ Y ≧ 0.22X + 4.3
Is desirable.

  When the number of poles is increased, the magnetomotive force per stator coil can be reduced, and the demagnetizing magnetic field received by the magnet is also reduced by this magnetomotive force, making it difficult for the magnet to demagnetize. Without changing, the magnet can be made thinner. As a second embodiment, application to a 50-pole 60-slot motor will be described. FIG. 7 is a sectional view of an electric motor having 50 poles and 60 slots. The permanent magnet 15 of this motor is a rare earth magnet that does not contain dysprosium. This motor is an abduction type (outer rotor type) motor in which the rotor 11 is rotatably disposed outside the stator 13. The rotor 11 is composed of a rotor core 12 and 50 permanent magnets 15, and the stator 13 is composed of a stator core 14 and 60 coils 17 wound around 60 teeth 16. Yes. The rotor core 12 and the stator core 14 are constituted by laminated steel plates in which electromagnetic steel plates are laminated.

FIG. 8 shows the relationship between the magnet thickness and the demagnetization factor for each electromagnetic steel sheet under the same driving conditions. Here, reduced permeability, E ₀ the induced voltage before supplying a demagnetizing current, the induced voltage after a current of demagnetizing current as E _1, from the equation _{(E 0 -E 1) / E} 0 × 100 This is the calculated value. It can be seen that the smaller the iron loss, the lower the magnet temperature.

FIG. 9 shows the relationship between the limit magnet thickness when the demagnetization factor is 0% and the electromagnetic steel sheet. The vertical axis represents the magnet thickness, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. From FIG. 9, in a 50 pole 60 slot motor using a neodymium rare earth magnet that contains iron, neodymium, and boron, but does not contain dysprosium, the maximum magnetic flux density is 1 at a frequency of 50 Hz of the electrical steel sheet used for the rotor and stator. When the iron loss at 5T is X, and the magnet thickness is Y,
Y ≧ 0.19X + 3.7
If so, the demagnetization rate can be reduced to 0%. From the difference in cost between a magnet with a Dy content of 0% and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
0.19X + 4.4 ≧ Y ≧ 0.19X + 3.7
Is desirable.

  As a third embodiment, application to a 60-pole 72-slot motor will be described. FIG. 10 is a sectional view of a 60 pole 72 slot electric motor. The permanent magnet 15 of this motor is a rare earth magnet that does not contain dysprosium. This motor is an abduction type (outer rotor type) motor in which the rotor 11 is rotatably disposed outside the stator 13. The rotor 11 is composed of a rotor core 12 and 60 permanent magnets 15, and the stator 13 is composed of a stator core 14 and 72 coils 17 wound around 72 teeth 16. Yes.

FIG. 11 shows the relationship between the magnet thickness and the demagnetization factor for each electromagnetic steel sheet under the same driving conditions. Here, reduced permeability, E ₀ the induced voltage before supplying a demagnetizing current, the induced voltage after a current of demagnetizing current as E _1, from the equation _{(E 0 -E 1) / E} 0 × 100 This is the calculated value. It can be seen that the smaller the iron loss, the lower the magnet temperature.

FIG. 12 shows the relationship between the limit magnet thickness when the demagnetization factor is 0% and the electrical steel sheet. The vertical axis represents the magnet thickness, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. From FIG. 12, in a 60 pole 72 slot motor using a neodymium rare earth magnet that contains iron, neodymium, and boron but does not contain dysprosium, the maximum magnetic flux density is 1 at a frequency of 50 Hz of the electrical steel sheet used for the rotor and stator. When the iron loss at 5T is X, and the magnet thickness is Y,
Y ≧ 0.16X + 3.1
If so, the demagnetization rate can be reduced to 0%. From the difference in cost between a magnet with a Dy content of 0% and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
0.16X + 3.7 ≧ Y ≧ 0.16X + 3.1
Is desirable.

From the first, second, and third embodiments, the limit magnet thickness that can ensure the demagnetization resistance defined by the relationship between the number of poles and the iron loss is known. That is, the number of poles M, the iron loss X, and the demagnetization resistance can be secured by plotting the values of the number of poles and the coefficient of iron loss X, and the number of poles and the constant of Examples 1-3. The relational expression with the magnet thickness Y is obtained. In an M pole motor, when the iron loss at a maximum magnetic flux density of 1.5 T is X at a frequency of 50 Hz of a magnetic steel sheet used for the rotor and stator, and the magnet thickness is Y,
Y ≧ (−0.003M + 0.34) X−0.06M + 6.7
If so, the demagnetization rate can be reduced to 0%.

From the difference in cost between a Dy-free magnet and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
(−0.003M + 0.34) X−0.075M + 8.18 ≧ Y ≧ (−0.003M + 0.34) X−0.06M + 6.7
Is desirable.

  In the above, the Example using the neodymium rare earth magnet which contains iron, neodymium, and boron but does not contain dysprosium was shown.

In the magnet added with dysprosium, the magnet thickness can be further reduced. An embodiment using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and having a dysprosium content of 2.5% or less will be described. As this magnet, a magnet having a room temperature coercive force of about H _cb = 980 kA / m is assumed.

As a fourth embodiment, application to a 40-pole 48-slot motor using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and having a dysprosium content of 2.5% or less will be described. The only difference from the first embodiment is the magnet used, and a sectional view of this motor is shown in FIG. FIG. 13 shows the relationship between the magnet thickness and the demagnetization factor for each electromagnetic steel sheet under the same driving conditions. Here, reduced permeability, E ₀ the induced voltage before supplying a demagnetizing current, the induced voltage after a current of demagnetizing current as E _1, from the equation _{(E 0 -E 1) / E} 0 × 100 This is the calculated value. It can be seen that the smaller the iron loss, the lower the magnet temperature.

FIG. 14 shows the relationship between the limit magnet thickness when the demagnetization factor is 0% and the electromagnetic steel sheet. The vertical axis represents the magnet thickness, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. From FIG. 14, a 40 pole 48 slot motor using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and a dysprosium content of 2.5% or less is used for a rotor and a stator. When the iron loss at the maximum magnetic flux density of 1.5 T at the frequency of 50 Hz of the magnetic steel sheet is X, and the magnet thickness is Y,
Y ≧ 0.11X + 3.3
If so, the demagnetization rate can be reduced to 0%. From the difference in cost between a magnet with a Dy content of 2.5% and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
0.11X + 3.8 ≧ Y ≧ 0.11X + 3.3
Is desirable.

Next, an example using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and having a dysprosium content of 4.5% or less will be described. As this magnet, a magnet having a room temperature coercive force of about H _cb = 940 kA / m is assumed.

As a fifth embodiment, application to a 40-pole 48-slot motor using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and having a dysprosium content of 4.5% or less will be described. The only difference from the first embodiment is the magnet used, and a sectional view of this motor is shown in FIG. FIG. 15 shows the relationship between the magnet thickness and the demagnetization factor for each electromagnetic steel sheet under the same driving conditions. Here, reduced permeability, E ₀ the induced voltage before supplying a demagnetizing current, the induced voltage after a current of demagnetizing current as E _1, from the equation _{(E 0 -E 1) / E} 0 × 100 This is the calculated value. It can be seen that the smaller the iron loss, the lower the magnet temperature.

FIG. 16 shows the relationship between the limit magnet thickness when the demagnetization factor is 0% and the electromagnetic steel sheet. The vertical axis represents the magnet thickness, and the horizontal axis represents the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5T. From FIG. 16, in a 40 pole 48 slot motor using a neodymium rare earth magnet containing iron, neodymium, boron, dysprosium and having a dysprosium content of 4.5% or less, the frequency of the electrical steel sheet used is 50 Hz. When the iron loss at the maximum magnetic flux density of 1.5T is X, and the magnet thickness is Y,
Y ≧ 0.08X + 2.3
If so, the demagnetization rate can be reduced to 0%. From the difference in cost between a magnet with a Dy content of 4.5% and a neodymium magnet with a Dy content of about 8%, considering the upper limit of the magnet thickness,
0.08X + 2.5 ≧ Y ≧ 0.08X + 2.3
Is desirable.

  According to each of the above embodiments, the radial thickness of the rotor magnet is set according to the dysprosium content in the neodymium rare earth magnet constituting the rotor and the iron loss amount of the electromagnetic steel plates of the rotor and the stator. By defining, it is possible to provide a permanent magnet motor with a reduced cost as much as possible.

  Example 6 is an elevator drive hoist using the permanent magnet motor described in any one of Examples 1 to 5. As this embodiment, an elevator-driven hoisting machine in which a motor having a fully closed structure is installed in an elevator hoistway is suitable.

  According to this embodiment, it is possible to provide an elevator drive hoisting machine that secures demagnetization resistance and suppresses the cost of the motor as much as possible.

DESCRIPTION OF SYMBOLS 1 ... BH demagnetization curve of magnet temperature C 2 BH demagnetization curve of magnet temperature D 3 Permeance straight line 4 of magnet thickness Y ₁ Permeance straight line 5 of magnet thickness Y ₂ Knic point 6 no-load operating point at 7 ... magnet thickness Y ₁ at the operating point of the magnet temperature C at the operation point 8 ... magnet thickness Y ₁ of the magnet temperature C at the operation point 9 ... magnet thickness Y ₂ of the magnet temperature D 10 ... the operating point of the magnet temperature D at the magnet thickness _{Y 2} 11 ... rotor 12 ... rotor core 13 ... stator 14 ... stator core 15 ... permanent magnet 16 ... tooth 17 ... coil

Claims (15)

A permanent magnet motor comprising a rotor using an electromagnetic steel sheet and a neodymium rare earth magnet, and a stator using an electromagnetic steel sheet,
According to the dysprosium content in the neodymium rare earth magnet constituting the rotor and the iron loss amount of the rotor and stator electromagnetic steel sheet, the thickness of the neodymium rare earth magnet in the rotor is set to the radial thickness of the neodymium rare earth magnet. A permanent magnet motor with a thickness that does not cause magnet demagnetization. The permanent magnet motor according to claim 1,
The neodymium rare earth magnet is a neodymium rare earth magnet that contains iron, neodymium, boron, and does not contain dysprosium,
The central thickness of the neodymium rare earth magnet constituting the rotor is Ymm in the radial direction, and the electromagnetic steel sheet constituting the rotor and the stator has an iron loss of XW / kg at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T. And the rotor is M pole,
Y, X and M are
Y ≧ (−0.003M + 0.34) X−0.06M + 6.7
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 2,
Y, X and M are
(−0.003M + 0.34) X−0.075M + 8.18 ≧ Y ≧ (−0.003M + 0.34) X−0.06M + 6.7
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 2,
The rotor has 40 poles;
Y and X are
Y ≧ 0.22X + 4.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 3,
The rotor has 40 poles;
Y and X are
0.22X + 5.2 ≧ Y ≧ 0.22X + 4.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 2,
The rotor has 50 poles;
Y and X are
Y ≧ 0.19X + 3.7
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 3,
The rotor has 50 poles;
Y and X are
0.19X + 4.4 ≧ Y ≧ 0.19X + 3.7
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 2,
The rotor has 60 poles;
Y and X are
Y ≧ 0.16X + 3.1
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 3,
The rotor has 60 poles;
Y and X are
0.16X + 3.7 ≧ Y ≧ 0.16X + 3.1
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 1,
The neodymium rare earth magnet includes iron, neodymium, boron, dysprosium, and a dysprosium content is 2.5% or less neodymium rare earth magnet,
The central thickness of the neodymium rare earth magnet constituting the rotor is Ymm in the radial direction, and the electromagnetic steel sheet constituting the rotor and the stator has an iron loss of XW / kg at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T. And the rotor is 40 poles,
Y and X are
Y ≧ 0.11X + 3.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 10,
Y and X are
0.11X + 3.8 ≧ Y ≧ 0.11X + 3.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 1,
The neodymium rare earth magnet is iron, neodymium, boron, dysprosium, and a dysprosium content is 4.5% or less neodymium rare earth magnet,
The central thickness of the neodymium rare earth magnet constituting the rotor is Ymm in the radial direction, and the electromagnetic steel sheet constituting the rotor and the stator has an iron loss of XW / kg at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T. And the rotor is 40 poles,
Y and X are
Y ≧ 0.08X + 2.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to claim 12,
Y and X are
0.08X + 2.5 ≧ Y ≧ 0.08X + 2.3
A permanent magnet motor characterized by satisfying the following relationship. The permanent magnet motor according to any one of claims 1 to 13,
A permanent magnet motor characterized in that the magnet shape is a flat magnet, and is a surface magnet type in which the flat magnet is attached to a rotor made of an electromagnetic steel plate.   The elevator drive hoisting machine using the permanent magnet motor of any one of Claim 1 to 14.

Images