JP3857017B2 - Permanent magnet type reluctance type rotating electrical machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a permanent magnet type reluctance type rotating electrical machine that combines a permanent magnet and can be operated in a wide range with a small size and high output.
[0002]
[Prior art]
A conventional reluctance type rotating electrical machine does not require a coil for forming a field in the rotor, and the rotor 4 can be constituted only by an iron core 9 having irregularities as shown in FIG. For this reason, the reluctance type rotating electrical machine is characterized in that it has a simple structure and is inexpensive.
[0003]
The principle of generating the output of this reluctance type rotating electrical machine is as follows. In the reluctance type rotating electric machine, since the rotor 4 is uneven, the magnetic resistance is small at the convex portion, and the magnetic resistance is large at the concave portion. That is, the magnetic energy stored by passing a current through the armature winding 3 is different between the convex portion and the gap portion on the concave portion. This change in magnetic energy generates an output. Further, the convex portion and the concave portion are not limited to geometrically concave and convex shapes, but may be any shape that allows magnetic irregularities to be formed (that is, a shape in which the magnetic resistance and magnetic flux density distribution varies depending on the position of the rotor).
[0004]
Another high-performance rotating electrical machine is a permanent magnet rotating electrical machine. The configuration of the armature in this permanent magnet rotating electric machine is the same as that of the reluctance type rotating electric machine, but the permanent magnet is arranged on the entire rotor.
[0005]
[Problems to be solved by the invention]
Conventional rotating electrical machines have the following technical problems. In the reluctance type rotating electrical machine, the magnetic resistance differs at the position of the rotor due to the unevenness of the surface of the rotor core, and the gap magnetic flux density also changes. Due to this change, the magnetic energy changes and an output is obtained.
[0006]
However, as the current increases, local magnetic saturation increases at the convex portion (d-axis) of the rotor core that becomes the magnetic pole. As a result, the magnetic flux leaking to the recessed portion (q-axis) of the iron core between the magnetic poles increases, the effective magnetic flux decreases, and the output decreases. From the viewpoint of magnetic energy, the change in the gap magnetic flux density is moderated by the leakage magnetic flux generated by the magnetic saturation of the convex portion of the rotor core, and the change in magnetic energy becomes small. For this reason, the increase rate of the output with respect to the current decreases, and the output is eventually saturated. Further, the q-axis leakage magnetic flux induces an invalid voltage to lower the power factor.
[0007]
On the other hand, in the case of a permanent magnet motor using a rare earth permanent magnet with a high magnetic energy product as another type of high output rotating electrical machine, a high magnetic field is obtained by placing a permanent magnet with a high magnetic energy product on the surface of the rotor core. Can be formed in the gap of the electric motor, so that small size and high output are possible.
[0008]
However, since the magnetic flux of the permanent magnet is constant, the voltage induced in the armature winding increases in proportion to the rotation speed. Therefore, when performing variable speed operation over a wide range up to high speed rotation, the field magnetic flux cannot be reduced. Therefore, if the power supply voltage is constant, it is difficult to perform a constant output operation that is twice or more the base speed.
[0009]
The present invention has been made to solve the conventional technical problem, and an object of the present invention is to provide a permanent magnet type reluctance type rotating electrical machine that is compact and has high output and capable of wide-range variable speed operation.
[0018]
[Means for Solving the Problems]
The permanent magnet type reluctance type rotating electrical machine according to the first aspect of the present invention includes a stator having an armature winding, a portion inside the stator that is easy to pass magnetic flux (d-axis), and a portion that is difficult to pass magnetic flux (q A plurality of cavities are provided so as to be symmetrically arranged with respect to each of the q axes, and a plurality of magnetic barriers are provided with respect to the q axis of the cavities. A rotor in which permanent magnets are arranged in symmetric cavities on both sides thereof, the magnetic resistance is maximized at the center of the q-axis, is symmetric with respect to the q-axis, and is a rotor with stator core teeth. The width Ls at the base at the side is 0.45 × πRr / Ns ≦ Ls ≦ 0.65 × πRr / Ns where the number of slots is Ns and the rotor diameter is Rr.
[0019]
According to a second aspect of the present invention, in the permanent magnet type reluctance type rotating electric machine according to the first aspect, the cavity located in the q-axis direction is shaped like a rhombus or a shape equivalent thereto.
According to a third aspect of the present invention, there is provided a permanent magnet type reluctance type rotating electrical machine having a stator having an armature winding, a portion (d-axis) where the magnetic flux easily passes inside the stator and a portion where the magnetic flux hardly passes (q A plurality of cavities are provided so as to be symmetrically arranged with respect to each of the q axes, and a plurality of magnetic barriers are provided with respect to the q axis of the cavities. A rotor in which permanent magnets are arranged in symmetric cavities on both sides thereof, the magnetoresistance being maximized at the center of the q axis, symmetric with respect to the q axis, and centered on the rotor center When the angle between the two permanent magnets arranged closest to and symmetrically with the d-axis is θ, the angle θ is 0.28 × 360 ° / P ≦ θ ≦ 0.4 × 360 ° / P (P Is the number of poles).
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
[First Embodiment]
FIG. 1 is a radial cross-sectional view of a permanent magnet type reluctance rotary electric machine according to a first embodiment of the present invention. The stator 1 includes a stator core tooth 2 and armature windings 3 on which electromagnetic steel plates are laminated. As shown in detail in FIG. 2, a plurality of cavities are formed in the rotor 4, and permanent magnets 6 are inserted into the cavities arranged in the V shape. The cavity 5 in which the permanent magnet 6 is not inserted has a rhombus or similar shape so that the cavity width is maximized in the q-axis direction where magnetic flux is difficult to pass, and the cavity width is narrowed symmetrically with respect to the q-axis. It is.
[0022]
Next, the operation of the permanent magnet type reluctance type rotating electrical machine of the first embodiment will be described.
[0023]
<Generation of torque>
The rotor 4 has magnetic resistance irregularities due to the cavity 5. The gap magnetic flux density is high at the portion where the magnetic resistance is small, and conversely, the gap magnetic flux density is small at the portion where the magnetic resistance is large. A reluctance torque is generated by this change in magnetic flux density.
[0024]
At this time, by adopting a structure in which the magnetic resistance is maximized at the center of the q axis, the gap magnetic flux density difference can be remarkably increased, and the torque can be increased. For that purpose, it is preferable that the shape of the cavity 5 in which the permanent magnet 6 is not inserted is a rhombus or a shape equivalent thereto as described above. Further, as shown in FIG. 3, when the cavity 5 in the q-axis direction penetrates the outer periphery of the rotor core and opens into the gap, the gap magnetic flux density difference can be further increased and the torque can be increased.
[0025]
Further, a permanent magnet 6 is arranged in the rotor core at a portion having a large magnetoresistance as the q axis. The permanent magnet 6 cancels the magnetic flux due to the q-axis current distributed in the q-axis direction with the magnetic flux of the permanent magnet 6. For this reason, the gap magnetic flux density is further reduced at locations where the magnetic resistance is large. As a result, the change in the gap magnetic flux density between the portion having the large magnetic resistance and the portion having the small magnetic resistance becomes large, and the reluctance torque is increased and the power factor is improved. Further, since the permanent magnet 6 is arranged in a V shape, the magnetization direction is directed to the center of the q-axis, thereby increasing the magnetizing force of the permanent magnet 6 with respect to the magnetic flux of the q-axis current.
[0026]
In the rotating electrical machine of the present embodiment, the amplitude value of the fundamental wave of the gap magnetic flux density of the permanent magnet 6 is set to 0.3 to 0.6 T, preferably 0.4 to 0.5 T. At this time, the magnetic flux by the q-axis current and the magnetic flux by the permanent magnet 6 cancel each other at the rated load, and the interlinkage magnetic flux of the q-axis becomes zero. Thereby, since an output is generated with a small magnetic flux, the power factor is increased and the iron loss is also reduced. At the same time, magnetic saturation is alleviated and output is improved.
[0027]
<Variable continuous operation and efficiency>
In a general permanent magnet motor and an embedded permanent magnet motor (IPM), the air gap magnetic flux density of the permanent magnet is as high as about 1 T, and the induced voltage is also high. Iron loss is also significant. On the other hand, in the rotating electrical machine of the present embodiment, the interlinkage magnetic flux of the permanent magnet 6 is about 0.4 T, and a large output can be obtained even with 1/3 to 1/2 of the magnetic flux of a normal permanent magnet motor. For this reason, there are the following advantages.
[0028]
Since an excessive induced voltage does not occur at high speed rotation, the power element and capacitor of the inverter that is the power source are not damaged by the overvoltage.
[0029]
In this rotating electrical machine, the d-axis current is an excitation current that mainly forms a magnetic field, and the q-axis current is a torque current. Therefore, if the d-axis current, which is the excitation current, is reduced as the rotation speed is increased, it can be easily operated up to a high speed rotation at a constant voltage, and is weakened so as to cancel the excessive induced voltage caused by the magnetic flux of the permanent magnet as in a permanent magnet motor. It is not necessary to pass a large current due to the magnetic flux. Moreover, the high-frequency iron loss caused by the weak magnetic flux is also small.
[0030]
Also, with this rotating electrical machine, the d-axis excitation current and the q-axis torque current can be changed according to the operating conditions, and since it can be operated in an optimal state, it can be used in a wide range from light load to high load, from low speed to high speed rotation. Efficiency is improved. For example, since the exciting current is reduced at light loads, the d-axis magnetic flux amount is reduced and the iron loss is reduced.
[0031]
<Reliability>
Since the periphery of the permanent magnet 6 is covered with a rotor core made of a magnetic material, the demagnetizing field in the magnet 6 is small, and the permanent magnet 6 operates in a region with a high permeance coefficient. For this reason, the permanent magnet 6 is not easily demagnetized even if a large demagnetizing field due to current acts. Furthermore, the NdFeB magnet can be applied even at a high temperature of 200 ° C. without irreversible demagnetization.
[0032]
Further, since the interlinkage magnetic flux of the armature winding 3 by the permanent magnet 6 is small, even if the winding is electrically short-circuited, an excessive short-circuit current does not flow and the winding is not burned. Furthermore, even when this rotating electrical machine is applied to a drive motor such as an electric vehicle or a train, sudden braking does not act at the time of a short circuit failure, and the braking force during rotation is slight, so that the vehicle can be pulled. it can.
[0033]
In addition, even if the permanent magnet 6 is irreversibly demagnetized, reluctance torque is mainly used in this rotating electrical machine, so that the output is reduced, but it can be driven as a pure reluctance motor.
[0034]
In the permanent magnet type reluctance type rotating electrical machine of the above-described embodiment, an equal amount of the permanent magnet 6 is used, and as shown in FIG. When the angle formed by the two permanent magnets 6 is θ, and represented by θ = K × 360 ° / P using the number of poles P and the coefficient K, the relationship between the angle coefficient K and the torque is as shown in FIG.
[0035]
From this result, it can be seen that the torque significantly increases when the angle coefficient K is 0.28 ≦ K ≦ 0.4 (preferably 0.30 ≦ K ≦ 0.35). That is, the angle θ is set to 0.28 × 360 ° / P ≦ θ ≦ 0.4 × 360 ° / P (preferably 0.30 × 360 ° ≦ θ ≦ 0.35 × 360 ° / P). Thus, a large torque can be obtained.
[0036]
This can be applied to all other embodiments described below.
[0037]
[Second Embodiment]
Next, a permanent magnet type reluctance type rotating electrical machine according to a second embodiment of the present invention will be described. The second embodiment is characterized in that the rotor 4 is divided.
[0038]
In the stator 1, one armature winding 3 is wound around each stator core tooth 2. In such concentrated winding, slot skew that is generally performed is difficult, and a large torque ripple is generated. When the number of slots Ns, the number of poles P, and q = Ns / (3 × P), when q = n + 1/2, the gap has the same wavelength as the distance between the slot centers (slot pitch) of adjacent slots. Although the magnetic flux density distribution can be canceled out, the secondary harmonic component cannot be canceled out.
[0039]
Therefore, in the second embodiment, as shown in FIG. 5, the rotor 4 is divided into a rotor A7 and a rotor B8, and the permanent magnet 6 and the cavity 5 are divided by a quarter of the slot pitch between them. The structure is shifted only in the circumferential direction.
[0040]
Thereby, as shown in the graph of FIG. 6, the secondary harmonic component is canceled, and the torque ripple can be reduced.
[0041]
[Third Embodiment]
The permanent magnet type reluctance type rotating electrical machine of the third embodiment is characterized by the shape of the stator core teeth in the stator 1.
[0042]
As shown in FIG. 7, the width of the root on the rotor side of the stator core teeth 2 is Ls. Then, the relationship between the coefficient J and the generated torque was examined when the slot number Ns and the rotor radius Rr were set to Ls = J × πRr / Ns (J is a coefficient). However, the current density of the current flowing through the armature winding 3 at this time was constant.
[0043]
FIG. 8 shows the result. When the coefficient J is J <0.45, the stator core teeth 2 are magnetically saturated and the torque is reduced. On the other hand, when J> 0.65, the total of current values that can flow in the slot is reduced, and the torque is reduced. As for the coefficient J, a high torque was stably obtained when 0.45 ≦ J ≦ 0.65.
[0044]
Further, as shown in FIG. 9, even when the tip 2A is attached to the stator core tooth 2 at the closest portion of the stator as shown in FIG. 9, if the length of the base portion of the tip 2A is Ls, the same result is obtained. Is obtained.
[0045]
【The invention's effect】
As described above, in the permanent magnet type reluctance type rotating electrical machine of the present invention, a rotating electrical machine having a large difference in inductance depending on the rotor position is obtained, and furthermore, the magnetic flux due to the q-axis current is canceled by the magnet so that it becomes almost zero. High output and high power factor are possible.
[0046]
In the permanent magnet type reluctance type rotating electrical machine of the present invention, a high output can be obtained even if the amount of magnetic flux of the permanent magnet is small, and the amount of magnetic flux in the rotating electrical machine can be adjusted by the excitation current. It can be driven and can operate efficiently in a wide range from light load to high load and from low speed to high speed.
[0047]
In the permanent magnet type reluctance type rotating electrical machine of the present invention, it is possible to further suppress demagnetization of the permanent magnet, there is no possibility of damaging the inverter as a power source due to the induced voltage of the permanent magnet, and at the time of short-circuit failure of the armature winding The reliability is high in many respects, such as that the sudden braking does not act and the permanent magnet can be driven even if it is demagnetized.
[Brief description of the drawings]
FIG. 1 is a radial cross-sectional view of a permanent magnet type reluctance rotary electric machine according to a first embodiment of the present invention.
FIG. 2 is a radially enlarged cross-sectional view of a rotor in the above embodiment.
FIG. 3 is an enlarged sectional view in the radial direction of another structural example of the rotor in the embodiment.
FIG. 4 is a graph showing a change characteristic of torque generated by a rotating electric machine according to the arrangement position of a permanent magnet in the embodiment.
FIG. 5 is a perspective view of a rotor according to a second embodiment of the present invention.
FIG. 6 is a characteristic graph of torque generated by each rotor divided body and combined torque as a rotor in the embodiment.
FIG. 7 is an enlarged radial sectional view of a stator according to a third embodiment of the present invention.
FIG. 8 is a characteristic graph showing the relationship between the width of the stator core teeth and the torque in the embodiment.
FIG. 9 is an enlarged sectional view in the radial direction of another structural example of the stator in the embodiment.
FIG. 10 is a radial sectional view of a conventional reluctance rotating electrical machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stator 2 ... Stator core tooth 3 ... Armature winding 4 ... Rotor 5 ... Cavity 6 ... Permanent magnet 7 ... Rotor A
8 ... Rotor B

Claims (3)

A stator with armature windings;
A plurality of cavities are arranged symmetrically with respect to each of the q axes so that portions (d-axis) that are easy to pass magnetic flux and portions (q-axis) that are difficult to pass magnetic flux are alternately formed inside the stator. A plurality of magnetic barriers are provided, and a rotor in which permanent magnets are arranged in cavities at symmetrical positions on both sides of the cavity with respect to the q axis,
The magnetoresistance is maximized at the center of the q axis, symmetric with respect to the q axis, and
The width Ls at the root of the stator core teeth on the rotor side is 0.45 × πRr / Ns ≦ Ls ≦ 0.65 × πRr / Ns where the number of slots is Ns and the rotor diameter is Rr. Permanent magnet type reluctance type rotating electrical machine. The permanent magnet type reluctance type rotating electrical machine according to claim 1, wherein the cavity positioned in the q-axis direction has a rhombus shape or a shape equivalent thereto. A stator with armature windings;
A plurality of cavities are arranged symmetrically with respect to each of the q axes so that portions (d-axis) that are easy to pass magnetic flux and portions (q-axis) that are difficult to pass magnetic flux are alternately formed inside the stator. A plurality of magnetic barriers are provided, and a rotor in which permanent magnets are arranged in cavities at symmetrical positions on both sides of the cavity with respect to the q axis,
The magnetoresistance is maximized at the center of the q axis, symmetric with respect to the q axis, and
Assuming that an angle formed by the two permanent magnets arranged closest to and symmetrically with respect to the d-axis around the rotor center is θ, the angle θ is 0.28 × 360 ° / P ≦ θ ≦ 0.4. The permanent magnet type reluctance rotating electric machine according to claim 1, wherein x is 360 ° / P (P is the number of poles).

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