JP3776171B2 - Magnet rotor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an internal rotation type rotor equipped with a permanent magnet typified by an electric motor for driving a compressor of a refrigerator or an air conditioner, and more particularly, a so-called interior-type rotor constructed by embedding a magnet in an iron core of a rotor. The present invention relates to a rotor of a permanent magnet motor (hereinafter referred to as IPM).
[0002]
[Prior art]
7 is known as an IPM rotor, and is disclosed in, for example, the pp. 385-388 (thesis number 306) of the National Institute of Electrical Engineers of Japan, National Convention Annual Conference 2007. This rotor is configured by providing a cylindrical iron core 11 with a shaft hole 9 and a plurality of housing holes 12 parallel to the shaft hole 9, and inserting a plate-like magnet 13 into the housing hole 12.
[0003]
The magnet 13 is a rare earth magnet such as an Nd-Fe-B magnet that is magnetically oriented parallel to the polar direction, and is magnetized so that adjacent ones have different polarities, as shown in FIG. In this case, a 4-pole field is formed. In addition, reference numeral 14 in the figure denotes a magnetic flux short-circuit prevention portion, which is formed by a space continuous with the accommodation hole 12, or by inserting a nonmagnetic material into this space as necessary, so that the interpolar portion of each magnet 13 is A magnetic short circuit prevents the amount of magnetic flux from the magnet from decreasing.
[0004]
The rotor is arranged in a stator having a three-phase winding to constitute a permanent magnet type synchronous motor, and rotates by exciting the stator winding through an inverter. Such an IPM is characterized by reverse saliency, so in the low speed range, so-called maximum torque control is performed in which both the reluctance torque generated thereby and the main magnetic flux torque generated by the magnet are driven at the maximum torque point. In the high speed range, it is effective to perform so-called advance phase control that supplements the main magnetic flux torque with reluctance torque, and is used for driving the above-described compressor and the like.
[0005]
That is, generally, the torque T of the IPM is T1 as the main magnetic flux torque and T2 as the reluctance torque.
T = T1 + T2 (1)
If the amount of magnetic flux by the magnet is Φ, the q-axis current is Iq, the d-axis current is Id, the q-axis inductance is Lq, and the d-axis inductance is Ld,
T1 = Φ · Iq (2)
T2 = (Ld−Lq) Id · Iq (3)
It is represented by
[0006]
[Problems to be solved by the invention]
In the rotor of the IPM as shown in FIG. 7, the magnet 13 is embedded near the center of the iron core 11, which actively uses the iron core portion interposed between the magnet and the air gap. This is to perform control with a large proportion of the reluctance torque component. Therefore, for the IPM using such a rotor, the component of the q-axis current Iq described in the above equations (2) and (3) is small and the component of the d-axis current Id is large. A configured inverter (hereinafter referred to as an Id component-based inverter) is used.
[0007]
However, in order to configure such an inverter, components such as a microcomputer and a current sensor become expensive, so that the Iq component is large and the Id component is small because of cost merit. In reality, there is a great demand for inexpensive inverters (hereinafter referred to as Iq component-based inverters). Driving the rotor of FIG. 7 with such an Iq component-based inverter leads to deterioration of IPM characteristics or inability to drive. In other words, the conventional rotor as shown in FIG. 7 has a very poor versatility.
[0008]
Also, when fabricating IPM rotor, the advance magnetized magnet 13, since the result in its strong workability of assembly of the rotating element is considerably for magnetic deterioration, generally, all the iron core 11 After magnets are installed, all the magnets are magnetized at the same number of poles at the same time by applying a magnetizing current to the stator windings or dedicated magnetizing windings arranged outside the rotor. It has become.
[0009]
In this case, the rotor shown in FIG. 7 will be described. As shown in FIG. 8, the magnetic orientation of the magnet 13 is formed parallel to the direction of the pole as shown by the solid line arrow 15, whereas the magnetized magnetic flux As shown by the broken line arrow 16, a substantially inclined flow with respect to the magnetic orientation 15 is formed at both end portions of the magnet corresponding to the vicinity of the interpolar portion of the magnetizing magnetic field. This phenomenon becomes more prominent as the magnet 13 is embedded closer to the center of the iron core 11. As a result, the magnetization of both ends of the magnet becomes insufficient, the magnetic force of the magnet at the time of completion is lowered, and the IPM characteristics deteriorate. It will be. In addition, since the quality of the magnetic force of the rotor is not stable, the values of the q-axis inductance Lq and the d-axis inductance Ld vary, resulting in poor matching with the inverter, resulting in extremely large variations in IPM characteristics. is there.
[0010]
[Means for Solving the Problems]
The present invention is provided with a shaft hole in the center of a cylindrical iron core and a plurality of housing holes in parallel with the shaft hole, the housing holes being provided near the outer peripheral portion of the iron core and inserting a plate-like magnet. And a magnet rotor magnetized so that adjacent magnets have different polarities. In the cross section perpendicular to the axial direction, the receiving hole has a hole edge formed in a chord shape with respect to an arc forming the outer diameter of the iron core, and the receiving hole has the chord-like hole edge. A magnet rotor in which a magnet formed with a length less than the length is inserted into a central portion of the accommodation hole by a stepped portion formed in a stepped direction in a direction of narrowing the hole width of the accommodation hole; To do.
The magnet rotor may be a magnet rotor in which a magnet is positioned and inserted through a nonmagnetic spacer so that the magnet is positioned at the center of the magnetic pole.
[0011]
[Action]
By arranging the accommodation holes including the magnetic flux short-circuit prevention portion in a straight line at each pole, the magnet is embedded near the outer peripheral portion of the iron core, and the amount of magnetic flux by the magnet can be increased. Further, by changing the length of the magnet, the ratio between the main magnetic flux torque component and the reluctance torque component can be easily changed while the iron core shape is left as it is. Furthermore, the gradient of the magnetizing magnetic flux at both ends of the magnet can be made gentle.
[0012]
【Example】
The rotor of the present invention will be described with reference to the drawings. FIG. 1 shows a cross section perpendicular to the axial direction of a rotor relevant to the present invention . The rotor is supported by a shaft inserted into the shaft hole 9 and is arranged inside an electric motor stator fixed to a casing or the like, and the outer peripheral portion of the iron core 1a is between the inner peripheral portion of the stator core. It is comprised so that it may oppose through a predetermined | prescribed space | gap. The iron core 1a is formed by laminating a large number of thin steel plates with a thickness of 0.35mm, 0.50mm, etc., punched into a predetermined shape, and the uneven portions due to the punching projections provided on each thin iron plate are adjacent to each other in the axial direction. And is fixed by a well-known caulking clamp means 7 which is fitted and fixed.
[0013]
The iron core 1a is provided with a plurality of housing holes 2a penetrating in the axial direction in parallel with the shaft hole 9, and a plate-like magnet 3a is inserted into the housing hole 2a by clearance fitting or press-fitting. The rotor is configured by fixing the end plates to the both ends in the axial direction by a plurality of caulking pins 8 penetrating the iron core 1a in the axial direction to cover the same. The magnet 3a is a rare earth magnet such as an Nd-Fe-B magnet that is magnetically oriented parallel to the polar direction, and is magnetized so that adjacent ones have different polarities. A field is formed.
[0014]
As shown in an enlarged view in FIG. 2, the accommodation hole 2a is formed by hole edges 6a and 6c and 6b and 6d formed in a chord shape with respect to an arc forming the outer diameter of the iron core 1a. Protrusions 5 projecting in the direction of narrowing the hole width are provided between the linear hole edges 6a and 6c and between 6b and 6d. A magnet 3a formed to a length less than the length of the straight portion is inserted into the central portion of the receiving hole 2a. As a result, spaces 4 serving as magnetic flux short-circuit prevention portions are formed at both ends of the accommodation hole 2a by the hole edges 6c and 6d, and the inter-electrode portions of the magnets 3a are magnetically short-circuited to reduce the amount of magnetic flux generated by the magnets. Is to be prevented.
[0015]
Thus, the accommodation holes 2a of the respective poles are provided in a straight line, and the magnets 3a formed with a length less than the lengths of the hole edges 6a and 6c or 6b and 6d are accommodated in the accommodation holes. The magnetic flux short-circuit prevention portion 4 can be provided in the inter-electrode portion, and at the same time, the magnet 3a is embedded near the outer periphery of the iron core 1a. Therefore, the amount of magnetic flux Φ in the above-described equation (2) can be increased, the main magnetic flux torque T1 can be increased, and it can be driven without any problem by an inverter mainly composed of Iq components. Of course, it can be driven without any trouble by an inverter mainly composed of Id components.
[0016]
When driven by an Id component-based inverter, in order to further improve the efficiency of the IPM, it is necessary to increase the reluctance torque T2 in the equation (3), and the most effective configuration is the absolute value of (Ld−Lq). It is good to enlarge. Therefore, this case can be dealt with as a configuration as shown in FIG. The rotor iron core 1a shown in FIG. 5 is the same as the iron core shown in the embodiment of FIGS. 1 and 2, and a magnet 3b formed shorter than the magnet 3a of FIGS. Contained. In this case, the magnet 3b is positioned by the nonmagnetic spacer 10b so as to be positioned at the center of the magnetic pole. By configuring like the rotor of FIG. 5, the amount of magnetic flux Φ by the magnet of the rotor decreases, so that the stator magnetic flux passing through the iron core 1a increases and the reluctance torque component can be increased. The advantage of this configuration is that it can be dealt with only by changing the magnet type without changing the type of the iron core 1a.
[0017]
Further, in the rotor shown in FIG. 1, since the magnet 3a is embedded near the outer peripheral portion of the iron core 1a as described above, a stator winding or a dedicated magnetizing winding arranged outside the rotor is used. When magnetizing by applying a magnetizing current, as shown in FIG. 6, the magnetizing magnetic flux 16 is in the both ends of the magnet 3a corresponding to the vicinity of the interpolar part of the magnetizing magnetic field with respect to the direction of the magnetic orientation of the magnet 3a. The slope becomes gentle. This is because the magnet 3a is arranged outside the position of the conventional magnet 13 indicated by a broken line in FIG. 6 so as to be close to the magnetic pole of the magnetized winding. As a result, the magnet 3a is substantially oriented at both ends. Sufficient magnetization along the direction is achieved.
[0018]
FIG. 3 shows a rotor according to an embodiment of the present invention . The rotor in FIG. 3 is formed by stepping the hole edges 6e and 6f at both ends with respect to the hole edges 6a and 6b at the center of the receiving hole 2b. The magnet 3a is positioned. If the width | variety of the magnetic flux short circuit prevention part 4 is obtained to such an extent that there is no functional trouble, also by this structure, the effect | action and effect similar to the rotor shown in FIG. 2 are acquired. Further, even when the short magnet 3b as shown in FIG. 5 is used, it can be easily analogized that it can be configured similarly to the rotor of FIG.
[0019]
FIG. 4 shows another rotor related to the present invention . The housing hole 2c is formed by the hole edges 6g and 6h of the shape obtained by removing the protrusion 5 in the housing hole 2a of the rotor shown in FIG. Is. In this case, by inserting the non-magnetic spacer 10a into the magnetic flux short-circuit prevention portion 4, the same magnet 3a as in FIG. 2 can be positioned and mounted at the center of the magnetic pole, and the same function and effect can be obtained. It is done. Moreover, the case where the short magnet 3b as shown in FIG. 5 is used can be dealt with by adjusting the length of the nonmagnetic spacer 10a.
[0020]
【The invention's effect】
According to the present invention, not only an Id component-based inverter but also an Iq component-based inverter can be driven without problems by a general-purpose rotor, and an inexpensive control device can be used. . Further, when pursuing the efficiency of IPM, there is a feature that a rotor having a configuration most suitable for each inverter can be easily formed by changing only the magnet type without changing the iron core type.
[0021]
In addition, since the magnet is sufficiently magnetized, there is no lack or variation in magnetic force at the time of completion, and the quality is stable, and the values of q-axis inductance and d-axis inductance are stable and matching with the inverter As a result, the IPM characteristics can be improved and the quality can be maintained.
[Brief description of the drawings]
FIG. 1 is a plan sectional view of a rotor related to the present invention .
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is an enlarged plan sectional view of a main part of a rotor according to an embodiment of the present invention .
FIG. 4 is an enlarged plan sectional view of a main part of another rotor related to the present invention .
FIG. 5 is an enlarged plan sectional view of a main part of a rotor according to another embodiment of the present invention .
FIG. 6 is an explanatory diagram showing a magnetic flux flow during magnetization.
FIG. 7 is a plan sectional view of a conventional rotor .
FIG. 8 is an explanatory diagram showing the relationship between the magnetic orientation of the magnet and the magnetized magnetic flux.

Claims (2)

With a shaft hole in the center of the cylindrical iron core, and a plurality of housing holes parallel to the shaft hole, the housing hole is provided near the outer periphery of the iron core and is configured by inserting a plate-like magnet, In a magnet rotor magnetized so that adjacent magnets have different polarities, a cross section perpendicular to the axial direction of the accommodation hole is a hole formed in a chord shape with respect to an arc forming the outer diameter of the iron core The housing hole has a stepped portion in which a magnet formed in a length less than the length of the chordal hole edge is stepped in the direction of narrowing the hole width of the housing hole. The magnet rotor is inserted into the central portion of the accommodation hole. The magnet rotor according to claim 1, wherein the magnet is positioned and inserted through a nonmagnetic spacer so as to be positioned at the center of the magnetic pole.

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