JP2011109734A - Rotating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating machine obtaining a high power by reducing leakage magnetic flux of a segment-shaped permanent magnet. <P>SOLUTION: A permanent magnet synchronous motor A includes a rotor 1 in which a plurality of segment-shaped permanent magnets 1b are buried along an outer peripheral surface 1a1 and a stator disposed opposite to the outer peripheral surface 1a1. The rotor 1 includes a pair of air layers 1c at a position sandwiching a passage path where the magnetic flux toward the outer peripheral surface 1a1 from the permanent magnet 1b passes through a rotor core 1a in the rotor core 1a between the permanent magnet 1b and the outer peripheral surface 1a1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotating machine such as an electric motor or a generator.

  Patent Document 1 discloses a permanent magnet synchronous motor (electric motor) as one form of a rotating machine. In this permanent magnet synchronous motor, a plurality of permanent magnets are inserted and arranged in the rotor to form poles. Then, the rotor is driven to rotate by energizing the armature winding on the stator side arranged so as to surround the rotor to form a rotating magnetic field.

JP 2000-228838 A

By the way, as a permanent magnet inserted into the rotor of the permanent magnet synchronous motor, a block-shaped (bar-shaped) permanent magnet is generally used from the viewpoint of cost. However, if the block-shaped permanent magnet is inserted and disposed along the outer peripheral surface of the rotor, a thickness is generated between the permanent magnet and the outer peripheral surface, and the magnetic resistance increases, resulting in a smaller output. Therefore, from the viewpoint of output, a segment-shaped (C-shaped, roof-shaped) permanent magnet that can reduce the thickness between the permanent magnet and the outer peripheral surface is used.
However, the segment-shaped permanent magnet has an arc-shaped surface facing the outer peripheral surface of the rotor, so that the magnetic flux tends to spread more easily than the block-shaped permanent magnet, and so-called leakage that goes into the rotor without going to the stator side. There is a problem that magnetic flux is easily born.

Some permanent magnet synchronous motors employ a sensorless control system that detects the position of a rotor based on a waveform of an electromotive force (EMF) output from a stator. In this method, since the current supplied to the armature winding is controlled according to the waveform of the induced electromotive force output from the stator, the waveform of the induced electromotive force output from the stator of the permanent magnet synchronous motor is A sine wave including only the fundamental wave as much as possible is desirable.
However, when leakage magnetic flux occurs, the induced electromotive force output from the stator includes many harmonic components (components having a higher frequency than the fundamental wave), and the waveform of the induced electromotive force becomes trapezoidal. And in detecting the position of the rotor based on the induced electromotive force, there is a problem that the trapezoidal wave shape of the waveform of the induced electromotive force hinders detection of the rotor position with high accuracy.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a rotating machine that can obtain a high output by reducing the leakage magnetic flux of a segment-shaped permanent magnet. Another object of the present invention is to provide a rotating machine capable of detecting the position of the rotor with high accuracy.

In order to solve the above problems, the present invention is a rotating machine having a rotor in which a plurality of segment-shaped permanent magnets are embedded along an outer peripheral surface, and a stator disposed so as to face the outer peripheral surface. In the rotor core between the permanent magnet and the outer peripheral surface, the rotor has a pair of nonmagnetic layers at a position sandwiching a passage where the magnetic flux from the permanent magnet toward the outer peripheral surface passes through the rotor core. The structure of having is adopted.
By adopting this configuration, in the present invention, the nonmagnetic layer having a low magnetic permeability is arranged so as to sandwich the passage of magnetic flux from the segment-shaped permanent magnet toward the outer peripheral surface of the rotor. Magnetic flux can be prevented to escape and leakage magnetic flux can be reduced, so that a large amount of magnetic flux can flow to the stator side.

In the present invention, the pair of nonmagnetic layers each have a rectangular shape, and employ a configuration in which the end portions on the outer peripheral surface side are inclined at a predetermined angle so as to be close to each other.
By adopting this configuration, in the present invention, the gap between the nonmagnetic layers on the outer peripheral surface side is narrowed, so that the magnetic flux from the segment-shaped permanent magnet toward the rotor outer peripheral surface can be concentrated and flowed to the stator side. High output can be obtained. Further, since the space between the nonmagnetic layers on the permanent magnet side is widened, more magnetic flux from the segment-shaped permanent magnet toward the outer peripheral surface of the rotor can flow to the stator side.

Further, in the present invention, based on the frequency analysis of the induced electromotive force output from the stator, a configuration is adopted in which the angle is set to a slope at which the voltage of the harmonic component of the induced electromotive force is lowest. To do.
By adopting this configuration, in the present invention, the non-magnetic layer is tilted at a tilt angle at which the voltage of the harmonic component is the lowest by frequency analysis of the induced electromotive force, and the waveform of the output induced electromotive force is converted into a sine wave By doing so, the position of the rotor is detected with high accuracy.

In the present invention, the nonmagnetic layer has an air layer.
By adopting this configuration, in the present invention, it is possible to form the nonmagnetic layer at low cost by providing a slit in the rotor core to form an air layer.

  In the present invention, the above-described rotating machine which is an electric motor or a generator is employed.

According to the present invention, there is provided a rotating machine including a rotor in which a plurality of segment-shaped permanent magnets are embedded along an outer peripheral surface, and a stator disposed so as to face the outer peripheral surface. In the rotor core between the permanent magnet and the outer peripheral surface, a configuration is adopted in which a pair of nonmagnetic layers is provided at a position sandwiching a passage where the magnetic flux from the permanent magnet toward the outer peripheral surface passes through the rotor core, By disposing a nonmagnetic layer having a low magnetic permeability so as to sandwich the passage of magnetic flux from the segment-shaped permanent magnet toward the outer peripheral surface of the rotor, magnetic flux that deviates from the passage is magnetically blocked to prevent leakage flux. It is possible to reduce the amount of magnetic flux that flows to the stator side.
Therefore, in the present invention, the leakage magnetic flux of the segment-shaped permanent magnet can be reduced to obtain a high output. Further, since there is no high frequency voltage component, there is no high frequency current component, and iron loss can be reduced.

It is a functional block diagram which shows the function structure of the permanent magnet synchronous motor control apparatus comprised by the permanent magnet synchronous motor which concerns on this embodiment. It is a cross-sectional view orthogonal to the rotation center axis of the permanent magnet synchronous motor according to the present embodiment. It is the elements on larger scale which show the structure of the rotor of the permanent magnet synchronous motor which concerns on this embodiment. It is the elements on larger scale which show the structure of the rotor of the permanent magnet synchronous motor which concerns on 2nd Embodiment. It is a figure which shows the waveform of the induced electromotive force of the permanent magnet synchronous motor which concerns on 2nd Embodiment.

  Hereinafter, a rotating machine according to an embodiment of the present invention will be described with reference to the drawings. In the following description, an IPM (Interior Permanent Magnet) type permanent magnet synchronous motor (electric motor) is applied as an example of the rotating machine of this embodiment.

(First embodiment)
FIG. 1 is a functional block diagram showing a functional configuration of a permanent magnet synchronous motor control device configured by a permanent magnet synchronous motor A according to the present embodiment.
As shown in FIG. 1, the permanent magnet synchronous motor control device includes a permanent magnet synchronous motor A, a DC power supply B, an inverter C, an induced electromotive force (EMF) detection unit D, and a motor control unit E. .

The DC power supply B is one in which one or a plurality of batteries are connected in series, and outputs a predetermined DC power supply voltage to the inverter C.
The inverter C switches the DC voltage supplied from the DC power source B based on the inverter control signal supplied from the motor control unit E, thereby generating a three-phase motor drive signal composed of the U phase, the V phase, and the W phase. It is generated and supplied to the permanent magnet synchronous motor A.
The induced electromotive force detection unit D detects an induced electromotive force output from the U phase of the permanent magnet synchronous motor A, and outputs the detected induced electromotive force to the motor control unit E.

  The motor control unit E inputs and outputs signals to and from the internal memory composed of a CPU (Central Processing Unit), ROM (Read Only Memory) and RAM (Random Access Memory), and the inverter C and the induced electromotive force detection unit D. Permanent magnet synchronous motor comprising an interface circuit and the like, and outputting an inverter control signal to the inverter C based on the control program stored in the ROM and the induced electromotive force detected by the induced electromotive force detection unit D Control the operation of A.

FIG. 2 is a cross-sectional view orthogonal to the rotation center axis P of the permanent magnet synchronous motor A according to this embodiment.
The permanent magnet synchronous motor A has a rotor 1 and a stator 2. The rotor 1 has a cylindrical rotor core 1a and four permanent magnets 1b. The stator 2 has a substantially cylindrical stator core 2a and a winding (armature winding) 2b wound around the stator core 2a.

The stator core 2a is configured by laminating a plurality of metal core plates, and includes teeth 2a2 protruding from the yoke 2a1 formed in an annular shape toward the inner periphery at equal angular intervals. And the front-end | tip part of this teeth 2a2 forms the substantially circumferential inner peripheral surface as a whole.
A plurality of windings 2b are wound around the teeth 2a2, and the molding agent fixes the position of the winding 2b with respect to the teeth 2a2. The winding 2b is composed of a U-phase winding, a V-phase winding, and a W-phase winding, and a magnetic pole is generated by a motor drive signal corresponding to the three phases supplied from the inverter C. The direction of is switched. In the stator 2 having such a configuration, the inner peripheral surface faces the outer peripheral surface 1a1 of the rotor 1 through a predetermined gap.

The rotor 1 includes a cylindrical rotor core 1a and four permanent magnets 1b. The rotor core 1a is a laminated steel plate in which a plurality of hollow disk-shaped steel plates are laminated, and the rotary shaft 3 is press-fitted and fixed in a through hole provided on the central axis.
The permanent magnet 1b is formed in a segment shape (C shape, roof tile shape), and there are two permanent magnets 1b having an N-polarity and an S-polarity permanent magnet 1b on the outer peripheral side of the rotor core 1a. Each of them is embedded along the outer peripheral surface 1a1 of the rotor core 1a. Specifically, permanent magnets 1b having the polarity of the N pole and permanent magnets 1b having the polarity of the S pole are embedded alternately on the outer peripheral surface 1a1 side of the rotor core 1a.

FIG. 3 is a partially enlarged view showing the configuration of the rotor 1 of the permanent magnet synchronous motor A according to the present embodiment.
The rotor core 1a is provided with an air layer (non-magnetic layer) 1c mainly for the purpose of preventing a short circuit of magnetic flux by the segment-shaped permanent magnet 1b.
The air layer 1c is a hollow space extending linearly in the axial direction of the rotor 1, and in the rotor core 1a between the permanent magnet 1b and the outer peripheral surface 1a1, a magnetic flux from the permanent magnet 1b toward the outer peripheral surface 1a1 is generated. It is provided as a pair at a position sandwiching a passage that passes through the rotor core 1a. Each of the pair of air layers 1c of the present embodiment has a rectangular shape, and is arranged so as to be parallel to each other along a direction perpendicular to the central tangent of the segment-shaped permanent magnet 1b.

Next, the operation of the permanent magnet synchronous motor A configured as described above will be described.
First, upon receiving a permanent magnet synchronous motor start instruction, the motor control unit E causes the inverter C to output a motor drive signal to the permanent magnet synchronous motor A by outputting an inverter control signal.
In the permanent magnet synchronous motor A, when the winding 2b receives the motor drive signal supplied from the inverter C, a magnetic circuit is formed by the stator core 2a, the winding 2b, and the permanent magnet 1b, and the rotor 1 starts rotating.

At this time, the induced electromotive force detection unit D detects the induced electromotive force generated in the U-phase winding of the winding 2 b by the rotation of the rotor 1, and outputs the detected induced electromotive force to the motor control unit E.
When the induced electromotive force generated in the U-phase winding of the winding 2b of the permanent magnet synchronous motor A is input from the induced electromotive force detection unit D, the motor control unit E receives the rotor 1 based on the induced electromotive force waveform. And the inverter control signal corresponding to the determined rotational position of the rotor 1 is output to the inverter C, whereby each of the U phase, V phase and W phase corresponding to the rotational position of the rotor 1 is transmitted to the inverter C. A motor drive signal is output to the permanent magnet synchronous motor A.

  As shown in FIG. 3, the rotor 1 of the present embodiment is provided with an air layer 1 c. Since the air layer 1c (air) is a nonmagnetic material having a lower magnetic permeability than the rotor core 1a, the pair of air layers 1c are separated from each other at a predetermined interval in the rotor core 1a between the permanent magnet 1b and the outer peripheral surface 1a1. By providing the magnetic flux from the segment-shaped permanent magnet 1b (indicated by solid arrows in FIG. 3), the magnetic flux travels between the pair of air layers 1c in the direction of the winding 2b. For this reason, the magnetic flux at the end of the permanent magnet 1b does not go in the direction of the winding 1b but passes between the adjacent permanent magnet 1b or the adjacent permanent magnet 1b and goes in the inner direction of the rotor core 1a. It is possible to prevent the magnetic flux (indicated by a dotted arrow in FIG. 3) from being generated.

Therefore, according to the above-described embodiment, the permanent magnet having the rotor 1 in which a plurality of segment-shaped permanent magnets 1b are embedded along the outer peripheral surface 1a1 and the stator 2 disposed so as to face the outer peripheral surface 1a1. In the synchronous motor A, the rotor 1 has a rotor core 1a between the permanent magnet 1b and the outer peripheral surface 1a1 at a position sandwiching a passage where the magnetic flux from the permanent magnet 1b toward the outer peripheral surface 1a1 passes through the rotor core 1a. By adopting a configuration having a pair of air layers 1c, the air layer 1c having a low magnetic permeability is arranged so as to sandwich a passage of magnetic flux from the segment-shaped permanent magnet 1b toward the outer peripheral surface 1a1 of the rotor 1. The magnetic flux deviating from the passage can be magnetically blocked to reduce the leakage magnetic flux, so that a large amount of magnetic flux can flow to the stator 2 side.
Therefore, in this embodiment, the permanent magnet synchronous motor A which can reduce the leakage magnetic flux of the segment-shaped permanent magnet 1b and can obtain a high torque is obtained. Further, since the high frequency component of the voltage is eliminated, the high frequency component of the current is eliminated, and iron loss can be reduced.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.
FIG. 4 is a partially enlarged view showing the configuration of the rotor 1 of the permanent magnet synchronous motor A according to the second embodiment.

The pair of air layers 1c in the second embodiment are inclined at a predetermined angle so that the end portions on the outer peripheral surface 1a1 side are close to each other.
According to this configuration, since the space between the air layers 1c on the outer peripheral surface 1a1 side is narrowed, the magnetic flux of the permanent magnet 1b (indicated by solid arrows in FIG. 4) is generated between the pair of air layers 1c on the outer peripheral side of the rotor core 1a. Leakage magnetic flux concentrated in the direction of the winding 2b and concentrated between the end portions, passing between the adjacent permanent magnet 1b or the adjacent permanent magnet 1b and moving toward the inner direction of the rotor core 1a (indicated by a dotted arrow in FIG. 4) Is reduced). Moreover, since the magnetic flux which goes to the outer peripheral surface 1a1 from the permanent magnet 1b can be concentrated and it can be made to flow to the stator 2, the torque can be transmitted effectively. Moreover, since the space between the air layers 1c on the permanent magnet 1b side is widened, more magnetic flux from the segment-shaped permanent magnet 1b toward the outer peripheral surface 1a1 can be flowed to the stator 2 side.

The angle of the air layer 1c (inclination with respect to the direction perpendicular to the tangent to the central portion of the segment-shaped permanent magnet 1b) is based on the frequency analysis of the induced electromotive force output from the stator 2 and the harmonic component of the induced electromotive force. The angle at which the voltage is lowest is set.
FIG. 5 is a diagram showing a waveform of the induced electromotive force of the permanent magnet synchronous motor A according to the second embodiment. The waveform of the solid line in FIG. 5 shows the waveform of the induced electromotive force when the end portions on the outer peripheral surface 1a1 side of the air layer 1c are arranged close to each other (second embodiment), and the broken line in FIG. The waveform indicates the waveform of the induced electromotive force when the air layer 1c is arranged in parallel without being inclined (first embodiment).
As shown in FIG. 5, the waveform of the induced electromotive force generated from the winding 2b of the first embodiment is not a sine waveform but a trapezoidal waveform. The reason why the waveform of the induced electromotive force becomes a trapezoidal waveform is that the induced electromotive force includes not only the fundamental wave but also harmonics.
On the other hand, as shown in FIG. 5, the waveform of the induced electromotive force generated from the winding 2b of the second embodiment is a sine waveform. This is because the magnetic flux is concentrated and the leakage magnetic flux is further reduced, so that the harmonic component is reduced, and the induced electromotive force is constituted only by the fundamental wave.

  The optimum inclination angle of the air layer 1c arranged so as to sine-wave the induced electromotive force generated from the permanent magnet synchronous motor A is the width of the permanent magnet 1b, the outer diameter of the rotor core 1a, the thickness of the air layer 1c, and the like. Therefore, the induced electromotive force generated from the winding 2b is subjected to frequency analysis by fast Fourier transform (FFT) processing, and the inclination angle at which the voltage of the harmonic component becomes the lowest is set. Yes. As a result of the measurement, when the air layer 1c is tilted by about 10 degrees, the waveform of the induced electromotive force becomes a sine wave. However, distortion occurs when tilted 45 degrees or more, and 90 degrees is the same form as 0 degrees (first embodiment).

  As described above, in the permanent magnet synchronous motor A according to the second embodiment, the end on the outer peripheral side approaches the rectangular air layer 1c provided on the outer peripheral surface 1a1 side of the rotor core 1a of each permanent magnet 1b. The permanent magnet synchronous motor A is arranged by inclining the air layer 1c to an inclination angle at which the harmonic power becomes the lowest by frequency analysis of induced electromotive force by fast Fourier transform (FFT) processing. Since the waveform of the induced electromotive force output from the sine wave becomes a sine wave, the position of the rotor 1 can be detected more easily and accurately than in the past.

  Furthermore, by arranging the air layer 1c so as to approach the end on the outer peripheral side of the rotor core 1a, the air layer 1c passes between the adjacent permanent magnet 1b or the adjacent permanent magnet 1b toward the inner direction of the rotor core 1a. Since the leakage magnetic flux toward the head is reduced from the magnetic flux of the permanent magnet 1b, the torque can be increased.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the air layer 1c is provided in the rotor 1, but the present invention is not limited to this. The air layer 1c is mainly intended to prevent a short circuit of magnetic flux, and may be other than air as long as it is a non-magnetic material having a low magnetic permeability. For example, the resin layer may be formed by press-fitting a resin instead of the air layers 1c and 1d.
Furthermore, the amount of resin press-fit is adjusted to correct the rotational balance, but the amount of the resin layer can be variously changed without departing from the gist of the present invention.

  Further, for example, in the above embodiment, the shape of a general segment type permanent magnet 1b is shown and described in FIGS. 2 to 4, but the present invention is limited to the segment type permanent magnet 1b of this shape. Not. Since the shape of the end of the permanent magnet 1b can be various for convenience of the manufacturing process, for example, the present invention can be applied regardless of whether the shape of the end of the permanent magnet 1b is tapered or polygonal. The same effect can be obtained.

  Moreover, for example, in the above-described embodiment, the case where the present invention is applied to a permanent magnet synchronous motor (electric motor) is illustrated, but the present invention is not limited to this, and may be configured to be applied to a generator. Good.

  A ... Permanent magnet synchronous motor (rotary machine), 1 ... Rotor, 1a ... Rotor core, 1a1 ... Outer peripheral surface, 1b ... Permanent magnet, 1c ... Air layer (nonmagnetic layer), 2 ... Stator

Claims (5)

A rotary machine having a rotor in which a plurality of segment-shaped permanent magnets are embedded along an outer peripheral surface, and a stator disposed so as to face the outer peripheral surface,
The rotor has a pair of non-magnetic layers in a position between the permanent magnet and the outer peripheral surface at a position where a magnetic flux from the permanent magnet toward the outer peripheral surface passes through the rotor core. Rotating machine characterized by   2. The rotating machine according to claim 1, wherein each of the pair of nonmagnetic layers has a rectangular shape, and is inclined at a predetermined angle so that end portions on the outer peripheral surface side are close to each other.   In the pair of nonmagnetic layers, the angle is set to an inclination at which the voltage of the harmonic component of the induced electromotive force is lowest based on frequency analysis of the induced electromotive force output from the stator. The rotating machine according to claim 2.   The rotating machine according to claim 1, wherein the nonmagnetic layer includes an air layer.   It is an electric motor or a generator, The rotating machine as described in any one of Claims 1-4 characterized by the above-mentioned.

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