JP2012228077A - Permanent magnet type rotary electrical machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet type rotary electrical machine which achieves a highly efficient permanent magnet type rotary electrical machine by suppressing induction voltage by means of magnetic flux reduction during high-speed rotation, and can prevent damage to electronic components of an inverter.SOLUTION: A permanent magnet type rotary electrical machine 1 includes: a stator 2 having an exciting coil 6 wound therearoud; and a rotor 3 disposed a predetermined distance away from the stator so as to permit relative rotation therebetween. The rotor 3 includes a permanent magnet 9. The rotor is rotated by mutual action between a magnetic flux generated from the permanent magnet and a current passing through an exciting coil. The rotor includes a magnetic characteristics variable element 10, whose magnetic characteristics are changed by the stress exerted on the stator by the rotation of the rotor, thereby decreasing the magnetic fluxes of the permanent magnet.

Description

  The present invention relates to a permanent magnet type rotating electrical machine including a stator around which an excitation coil is wound, and a rotor provided with a permanent magnet and provided with a permanent magnet so as to be relatively rotatable with a predetermined gap.

  Permanent magnet type rotating electrical machines do not cause secondary copper loss compared to induction motors and do not need to pass an exciting current to generate magnetic flux, so when obtaining the same output as induction motors, higher efficiency and Miniaturization can be easily realized. Furthermore, in an embedded magnet structure (IPM: Interior Permanent Magnet) in which a permanent magnet is embedded in the rotor, a reluctance torque can be used in addition to the magnet torque, and thus further improvement in efficiency is expected.

  On the other hand, in a permanent magnet type rotating electrical machine, the field magnetic flux is obtained by a permanent magnet, so that the field magnetic flux is always constant, and the induced voltage of the rotating electrical machine is proportional to the rotational speed. At high speed rotation, the induced voltage by the permanent magnet becomes high, and when the induced voltage reaches the upper limit of the power supply voltage, the current necessary for output stops flowing. Furthermore, when the high induced voltage is applied to the electronic component of the inverter and exceeds the withstand voltage of the electronic component, the electronic component may break down.

  Therefore, a control method for reducing the magnetic flux in the d-axis direction by using a demagnetizing effect caused by the d-axis armature reaction by passing a negative d-axis current through the d-axis of the rotating machine, so-called weak magnetic flux control is well known. ing. However, in this case, it is necessary to continuously apply a demagnetizing field to the permanent magnet, and since a d-axis current that does not contribute to the output is continuously supplied, there is a problem that the copper loss increases and the efficiency deteriorates.

  In order to solve such a problem, for example, a permanent magnet type rotating electrical machine shown in Patent Document 1 is known. FIG. 7 shows a rotor 1 constituting the permanent magnet type rotating electrical machine disclosed in Patent Document 1. The rotor 1 includes a plurality of low coercive force permanent magnets 3 extending in a radial direction of the rotating iron core 2 and embedded at predetermined intervals in the circumferential direction, and two adjacent low coercive force permanent magnets. 3 and a plurality of high coercive force permanent magnets 4 extending in the circumferential direction so as to be sandwiched on the inner peripheral side and embedded in the rotating iron core 2. The low coercivity permanent magnet 3 is a magnet whose magnetic flux density is irreversibly changed by a magnetic field generated by the current of a stator (not shown) provided with a winding. The high coercivity permanent magnet 4 is a low coercivity permanent magnet 3. It is a magnet having a coercive force that is twice or more of.

  In Patent Document 1, a magnetic field is formed by flowing a short-time (about 100 μs to 1 ms) pulse current through the stator winding, and the low coercive force permanent magnet 3 is magnetized to generate a low coercive force. The induced voltage during high-speed rotation is controlled by adjusting the magnetic flux direction and the magnetic flux amount of the permanent magnet 3 and controlling the combined magnetic flux of the low coercive force permanent magnet 3 and the high coercive force permanent magnet 4.

JP 2006-280195 A

However, in the technique of Patent Document 1 as described above, a magnetizing current for adjusting the magnetic flux of the low coercive force permanent magnet 3 must be supplied from the outside depending on the rotational speed. That is, in the case of a variable speed load, it is necessary to frequently perform this magnetization operation. Further, since the current for performing the magnetizing operation is output from the inverter that controls the rotating machine, there is a possibility that an extra burden is placed on the power device of the inverter. Furthermore, if the inverter control device fails during high-speed rotation of the rotating electrical machine, the magnetic flux of the low coercive force permanent magnet 3 cannot be adjusted, and a high induced voltage is applied to the electronic components of the inverter, resulting in inverter breakdown. There is also a problem that causes failure.
Therefore, the present invention has been made in view of the above circumstances, and by reducing magnetic flux during high-speed rotation, the induced voltage is suppressed, realizing high-efficiency operation and preventing damage to the electronic components of the inverter. An object of the present invention is to provide a permanent magnet type rotating electrical machine that can be used.

In order to achieve the above object, a permanent magnet type rotating electrical machine according to claim 1 of the present application is arranged such that a stator around which an exciting coil is wound and a relative clearance with a predetermined gap between the stator and a permanent magnet. In the permanent magnet type rotating electrical machine in which the rotor rotates by the interaction between the magnetic flux generated by the permanent magnet and the current flowing through the exciting coil, the rotor is connected to the rotor. A magnetic characteristic variable element is provided that changes the magnetic characteristics by applying stress by rotation and reduces the magnetic flux of the permanent magnet.
According to the present invention, when the rotational speed of the rotor increases, the rotational centrifugal force of the rotor is applied as stress to the magnetic characteristic variable element, and the magnetic characteristic of the magnetic characteristic variable element changes to decrease the magnetic flux of the permanent magnet. Therefore, the induced voltage of the permanent magnet type rotating electrical machine can be suppressed.

According to a second aspect of the present invention, in the permanent magnet type rotating electric machine according to the first aspect, the magnetic characteristic variable element has a magnetic permeability as a result of a rotational centrifugal force acting as the stress acting on the rotation of the rotor. It is a changing giant magnetostrictive element.
According to the present invention, the magnetostrictive element constituting the variable magnetic property element has a large displacement and a large change in permeability according to the generated stress. Therefore, when the rotational speed of the rotor is increased, the magnetic flux of the permanent magnet is surely increased. Can be small.

The invention according to claim 3 of the present application is the permanent magnet type rotating electric machine according to claim 2, wherein the rotor is provided with the magnetic characteristic variable element, and a rotation center side of the rotor with respect to the magnetic characteristic variable element. The permanent magnet adjacent to the magnet is arranged so that the rotational centrifugal force generated in the permanent magnet acts on the magnetic characteristic variable element.
According to the present invention, as the rotational speed of the rotor increases, the rotational centrifugal force increases in proportion to the square of the rotational speed, and this rotational centrifugal force is applied as stress to the magnetic characteristic variable element. The magnetic flux can be reduced according to the rotational speed.

  According to a fourth aspect of the present invention, there is provided the permanent magnet type rotating electric machine according to the second aspect, wherein the rotor includes the magnetic characteristic variable element, and a rotation center side of the rotor with respect to the magnetic characteristic variable element. The permanent magnets adjacent to each other and a stress adjustment block adjacent to the permanent magnet on the rotation center side of the rotor, and the stress adjustment block is set to a predetermined mass. The rotational centrifugal force acting on the magnetic characteristic variable element is adjusted.

  According to a fifth aspect of the present invention, in the permanent magnet type rotating electric machine according to the second aspect, the rotor is provided with the magnetic characteristic variable element, and a rotation center side of the rotor with respect to the magnetic characteristic variable element. A stress adjusting block adjacent to the rotor and the permanent magnet adjacent to the rotation center side of the rotor with respect to the stress adjusting block, and the stress adjusting block is set to a predetermined mass. Thus, the rotational centrifugal force acting on the magnetic characteristic variable element is adjusted.

  According to these inventions of claims 4 and 5, since the stress (rotational centrifugal force) applied to the magnetic property variable element is changed by the mass of the stress adjustment block, it is not necessary to change the shape of the permanent magnet. Magnetic flux does not change, and the induced voltage of the permanent magnet type rotating electrical machine can be freely adjusted.

  According to the permanent magnet type rotating electrical machine of the present invention, when the rotational speed of the rotor increases, the rotational centrifugal force of the rotor is applied as stress to the magnetic characteristic variable element, and the magnetic characteristic of the magnetic characteristic variable element changes. Since the magnetic flux of the permanent magnet is reduced, the induced voltage of the permanent magnet type rotating electrical machine can be suppressed. Accordingly, high-speed rotation can be achieved without performing the flux-weakening control or by passing a small flux-weakening current, and it is not necessary to constantly flow a d-axis current for applying a demagnetizing field to the permanent magnet, and high efficiency. A permanent magnet type rotating electrical machine can be realized. Furthermore, the magnetic flux of the permanent magnet can be automatically adjusted according to the rotational speed of the rotor regardless of the external control circuit, and a high induced voltage is maintained even if the inverter fails during high-speed operation. It does not occur, and damage to the electronic components of the inverter can be prevented.

It is sectional drawing which shows the permanent magnet type rotary electric machine of 1st Embodiment which concerns on this invention. It is a graph which shows the characteristic (relationship between a compressive stress and magnetic permeability) of the magnetic characteristic variable element with which the permanent magnet type rotary electric machine which concerns on this invention is equipped. It is the graph which showed the state where the magnetic flux which generate | occur | produces with the permanent magnet of the permanent-magnet-type rotary electric machine which concerns on this invention reduces according to a rotational speed compared with the past. It is the graph which showed the relationship between the rotational speed of the permanent magnet type rotary electric machine which concerns on this invention, and an induced voltage compared with the past. It is sectional drawing which shows the rotor of the permanent-magnet-type rotary electric machine of 2nd Embodiment which concerns on this invention. It is sectional drawing which shows the rotor of the permanent-magnet-type rotary electric machine of 3rd Embodiment which concerns on this invention. It is sectional drawing which shows the rotor of the conventional permanent magnet type rotary electric machine.

DESCRIPTION OF EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.
FIG. 1 is a sectional view showing a permanent magnet type rotating electrical machine 1 according to a first embodiment of the present invention. The permanent magnet type rotating electrical machine 1 includes a cylindrical stator 2 and a rotor 3 that is opposed to the stator 2 by providing a predetermined air gap on the inner peripheral side of the stator 2.
In the stator 2, a plurality of slots 4 are formed at equal intervals in the circumferential direction on the inner peripheral surface side, and a plurality of magnetic pole teeth 5 are formed between adjacent slots 4 and 4. An excitation coil 6 wound in the slot 4 is wound around each magnetic pole tooth 5.

The rotor 3 includes a cylindrical rotor core 7, a plurality of slots 8 provided at predetermined intervals in the circumferential direction of the rotor core 7, and a plate-like permanent member disposed so as to overlap the slots 8. A magnet 9 and a magnetic property variable element 10 are provided.
Each slot 8 has a rectangular cavity 8 a whose longitudinal direction is orthogonal to the radial direction of the rotor core 7, and extends obliquely from both ends of the rectangular cavity 8 a toward the outer peripheral side of the rotor core 7. And the end side cavity 8b.

  The permanent magnet 9 and the magnetic property variable element 10 are fixed so as to overlap each other in the thickness direction. The variable magnetic property element 10 is arranged in the rectangular cavity 8a so as to be positioned on the outer side in the radial direction of the rotor core 7 with respect to the permanent magnet 9, and on the outer side in the radial direction of the rectangular cavity 8a. The facing surface of the variable magnetic property element 10 is fixed to the positioned inner wall, and a gap is provided between the inner wall positioned on the radially inner side of the rectangular cavity 8 a and the facing surface of the permanent magnet 9.

When the stress is applied to the variable magnetic property element 10, the magnetic property changes according to the speed and magnitude of the stress. As a specific example, a giant magnetostrictive element is used.
FIG. 2 shows the characteristics (relationship between compressive stress and permeability) of the giant magnetostrictive element. According to this figure, when the permeability is 100% when no compressive stress is applied to the giant magnetostrictive element, when the compressive stress is applied to the giant magnetostrictive element, the giant magnetostrictive element depends on the magnitude of the compressive stress. The permeability of decreases.

  When the rotor 3 of the permanent magnet type rotating electrical machine 1 starts rotating, the rotational centrifugal force generated in the permanent magnet 9 applies stress to the magnetic property variable element 10, and the magnetic permeability of the magnetic property variable element 10 rotates. Varies with speed. That is, as the rotational speed of the rotor 3 increases, the rotational centrifugal force generated in the permanent magnet 9 increases in proportion to the square of the rotational speed, the magnetic permeability of the variable magnetic property element 10 decreases, and the magnetic resistance of the magnetic circuit Becomes larger. Therefore, in the permanent magnet type rotating electrical machine 1 of the present embodiment, the flux linkage generated in the permanent magnet 9 decreases according to the rotation speed (see FIG. 3).

  Here, the induced voltage of the permanent magnet type rotating electrical machine 1 of the present embodiment is the sum of the flux linkage and the rotational speed. In the conventional permanent magnet type rotating electrical machine, the interlinkage magnetic flux of the permanent magnet is constant, so that the induced voltage is proportional to the rotational speed. On the other hand, in the permanent magnet type rotating electrical machine 1 according to the present embodiment, as described above, the interlinkage magnetic flux generated in the permanent magnet 9 decreases in accordance with the rotational speed. The induced voltage of the electric machine 1 is lower than in the conventional case where the induced voltage is proportional to the rotational speed (see FIG. 4).

  In the permanent magnet type rotating electrical machine 1 of the present embodiment, when the rotational speed of the rotor 3 increases, the rotational centrifugal force generated in the permanent magnet 9 embedded in the rotor core 7 is applied to the permanent magnet 9. As a result, stress is applied to the variable magnetic property element 10 arranged outside the rotor core 7 in the radial direction, and the magnetic permeability of the variable magnetic property element 10 is reduced. Accordingly, the interlinkage magnetic flux of the permanent magnet 9 is large and a large torque can be obtained at the time of low-speed rotation, and the interlinkage magnetic flux by the permanent magnet 9 decreases as the rotation speed increases. Voltage can be suppressed.

Accordingly, high-speed rotation can be performed without performing the flux-weakening control or by passing a small flux-weakening current, and it is not necessary to constantly flow a d-axis current for applying a demagnetizing field to the permanent magnet 9, which is highly efficient. The permanent magnet type rotating electrical machine 1 can be realized.
In addition, the permanent magnet type rotating electrical machine 1 of the present embodiment can automatically adjust the flux linkage by the permanent magnet 9 according to the rotational speed of the rotor 3 regardless of an external control circuit. Even if the inverter fails, a high induced voltage is not generated, and damage to the electronic components of the inverter can be prevented.
Further, the giant magnetostrictive element constituting the magnetic property variable element 10 has a large displacement and a large change in permeability according to the generated stress. Therefore, when the rotational speed increases, the interlinkage magnetic flux of the permanent magnet 9 is reliably reduced. The induced voltage of the permanent magnet type rotating electrical machine 1 can be reliably suppressed.

Next, FIG. 5 shows the rotor 3 which comprises the permanent magnet type rotary electric machine of 2nd Embodiment which concerns on this invention. In addition, the stator which comprises the permanent magnet type rotary electric machine of this embodiment is the same structure as the stator 2 shown in FIG. Also, the same components as those shown in FIG.
In the present embodiment, the permanent magnet 9, the magnetic property variable element 10, and the stress adjustment block 11 overlap with the rectangular cavities 8 a of the slots 8 provided at predetermined intervals in the circumferential direction of the rotor core 7. Has been placed.
The stress adjustment block 11 is a member that causes a rotational centrifugal force generated by rotation to act on the magnetic property variable element 10 as a stress, and is a block body having a predetermined mass made of a magnetic material or a non-magnetic material.

As in the first embodiment, a giant magnetostrictive element is used as the magnetic characteristic variable element 10.
The permanent magnet 9, the magnetic property variable element 10, and the stress adjustment block 11 are fixed so as to overlap each other in the thickness direction with the permanent magnet 9 positioned between the magnetic property variable element 10 and the stress adjustment block 11. The opposing surface of the variable magnetic property element 10 is fixed to the inner wall located on the radially outer side of the rectangular cavity portion 8a, and the inner wall located on the radially inner side of the rectangular cavity portion 8a faces the stress adjusting block 11. A gap is provided between the surface.

  In the present embodiment, when the rotor 3 of the permanent magnet type rotating electrical machine 1 starts rotating, the rotational centrifugal force generated in the permanent magnet 9 and the stress adjusting block 11 applies stress to the magnetic property variable element 10. The magnetic permeability of the variable magnetic property element 10 decreases as the rotational speed increases, the flux linkage generated in the permanent magnet 9 also decreases as the rotational speed increases, and the induced voltage is proportional to the rotational speed. Therefore, the induced voltage of the permanent magnet type rotating electrical machine can be suppressed.

  Here, in the permanent magnet type rotating electrical machine 1 of the present embodiment, the stress applied to the variable magnetic property element 10 is the rotational centrifugal force generated by the permanent magnet 9 and the stress adjusting block 11, thereby causing linkage between the permanent magnets 9. Magnetic flux and induced voltage can be adjusted freely. That is, in this embodiment, since the stress (rotational centrifugal force) applied to the magnetic property variable element 10 can be changed by the mass of the stress adjustment block 11, it is not necessary to change the shape of the permanent magnet 9, and the permanent magnet 9 Therefore, the induced voltage of the permanent magnet type rotating electrical machine can be freely adjusted.

  In FIG. 5, the permanent magnet 9 is positioned between the magnetic property variable element 10 and the stress adjustment block 11 and fixed to each other in the thickness direction, and these are arranged in the rectangular cavity 8 a of the slot. As shown in FIG. 6, the stress adjusting block 11 is positioned between the magnetic characteristic variable element 10 and the permanent magnet 9 and fixed in the thickness direction so as to be outside the rectangular cavity 8a in the radial direction. Even if the opposing surface of the magnetic property variable element 10 is fixed to the positioned inner wall and a gap is provided between the inner wall positioned inside the radial direction of the rectangular cavity 8a and the opposing surface of the permanent magnet 9, The same effect as in FIG. 5 can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Permanent magnet type rotary electric machine, 2 ... Stator, 3 ... Rotor, 4 ... Slot, 5 ... Magnetic pole teeth, 6 ... Excitation coil, 7 ... Rotor core, 8 ... Slot, 8a ... Rectangular hollow part, 8b ... End side cavity part, 9 ... Permanent magnet, 10 ... Variable magnetic property element, 11 ... Stress adjustment block

Claims (5)

A stator having an exciting coil wound thereon, and a rotor provided with a permanent magnet and a permanent magnet, and a stator provided with a permanent magnet, and a magnetic flux generated by the permanent magnet and the exciting coil. In the permanent magnet type rotating electrical machine in which the rotor rotates by interaction with the flowing current,
A permanent magnet type rotating electrical machine, wherein a magnetic characteristic variable element is provided on the rotor to change a magnetic characteristic when stress is applied by rotation of the rotor and to reduce a magnetic flux of the permanent magnet.   2. The permanent magnet type rotating electric machine according to claim 1, wherein the magnetic characteristic variable element is a giant magnetostrictive element whose permeability changes when a rotational centrifugal force due to rotation of the rotor acts as the stress.   The rotor is provided with the magnetic property variable element and the permanent magnet adjacent to the magnetic property variable element on the rotation center side of the rotor, and the rotational centrifugal force generated in the permanent magnet is 3. The permanent magnet type rotating electric machine according to claim 2, wherein the permanent magnet type rotating electric machine acts on the magnetic characteristic variable element. The rotor has the magnetic property variable element, the permanent magnet adjacent to the rotor center side of the rotor with respect to the magnetic property variable element, and the rotor center side of the rotor with respect to the permanent magnet. And a stress adjustment block adjacent to
3. The permanent magnet type rotating electric machine according to claim 2, wherein the stress adjusting block adjusts the rotational centrifugal force acting on the magnetic characteristic variable element by setting to a predetermined mass. The rotor, the magnetic property variable element, a stress adjustment block adjacent to the magnetic property variable element on the rotation center side of the rotor, and the rotation center of the rotor with respect to the stress adjustment block Arranging the permanent magnet adjacent to the side,
3. The permanent magnet type rotating electric machine according to claim 2, wherein the stress adjusting block adjusts the rotational centrifugal force acting on the magnetic characteristic variable element by setting to a predetermined mass.

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