JP4808529B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor that includes a permanent magnet in a rotor and can change the field characteristics of the permanent magnet.

  Conventionally, an outer peripheral rotor including a permanent magnet and an inner peripheral rotor including a permanent magnet are concentrically arranged, and either the outer peripheral rotor or the inner peripheral rotor is arranged around the other. There is known an electric motor that changes the relative phase between an outer circumferential rotor and an inner circumferential rotor by rotating in a direction (see, for example, Patent Document 1).

  In this electric motor, when the relative phase of both rotors is changed according to the rotational speed of the electric motor, the outer rotor and the inner rotor are rotated by a member that is displaced along the radial direction by the action of centrifugal force. Either one of the children is rotated in the circumferential direction with respect to the other. In addition, when the relative phase of both rotors is changed according to the speed of the rotating magnetic field generated in the stator, a control current is applied to the stator winding in a state where each rotor maintains the rotation speed due to inertia. The relative position in the circumferential direction of the outer peripheral side rotor and the inner peripheral side rotor is changed by energizing and changing the rotating magnetic field speed.

And the characteristic (ratio of induced voltage / rotation speed) of an electric motor can be made variable by changing the relative phase of an outer peripheral side rotor and an inner peripheral side rotor. Specifically, when the permanent magnet of the outer rotor and the permanent magnet of the inner rotor face each other with different polarities (same polarity arrangement), the field is in a stronger state (stronger field phase). Thus, the induced voltage becomes large. On the other hand, when the permanent magnet of the outer rotor and the permanent magnet of the inner rotor face each other with the same polarity (counter electrode arrangement), the field becomes weakened (weak field phase). The induced voltage becomes small.
JP 2002-204541 A

  By the way, as described above, in this type of electric motor, one of the outer peripheral rotor and the inner peripheral rotor is rotated in the circumferential direction with respect to the other, for example, from the strong field phase to the weak field. In the intermediate phase between the strong field phase and the weak field phase, the difference between the permanent magnet part of the outer rotor and the permanent magnet part of the inner rotor is changed. The opposite part of the poles remains. For this reason, even in the intermediate phase, the peak value of the induced voltage is as high as the strong field phase, and in order to reduce the induced voltage, a field weakening current is required for the stator winding, resulting in copper loss. There is an inconvenience that increases. In addition, since the relationship between the phase of the rotating rotor and the induced voltage constant (that is, the rotational speed ratio of the induced voltage) is not linear, it is difficult to control the motor based on the induced voltage constant. .

  The present invention has been made in view of the above circumstances, and can reduce the peak value of the induced voltage when the relative phase between the outer rotor and the inner rotor is an intermediate phase, An object of the present invention is to provide an electric motor that reduces copper loss and that can be easily controlled based on an induced voltage constant.

  In order to achieve such an object, the present invention provides an inner peripheral rotor having a plurality of substantially plate-shaped inner peripheral permanent magnets arranged along the circumferential direction, and a substantially plate arranged along the circumferential direction. An outer peripheral rotor having a plurality of outer peripheral permanent magnets arranged concentrically around the rotation shaft, and at least one of the inner peripheral rotor and the outer peripheral rotor is arranged in the circumferential direction. An electric motor comprising rotating means for rotating and changing a relative phase between the inner circumferential rotor and the outer circumferential rotor, the inner circumferential permanent magnet and the outer circumferential permanent magnet; Are arranged so that their long sides in the cross-sectional shape with respect to the direction parallel to the rotation axis face each other, and at least one of the inner peripheral permanent magnet and the outer peripheral permanent magnet is in a predetermined rotation direction. It is formed in a shape in which the short side on the opposite side is smaller than the short side on the opposite side. And said that you are.

  In the electric motor of the present invention, at least one of the inner circumferential side rotor and the outer circumferential side rotor is rotated in the circumferential direction by the rotating means, so that the gap between the inner circumferential side rotor and the outer circumferential side rotor is reduced. The relative phase of is changed.

  Here, for example, in a state in which the different polarities of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet face each other (same polarity arrangement), the relative phase between the inner peripheral side rotor and the outer peripheral side rotor is a strong field. Magnetic phase. Then, by rotating any one of the inner peripheral rotor and the outer peripheral rotor in a predetermined rotating direction by the rotating means, the same polarity of the inner peripheral permanent magnet and the outer peripheral permanent magnet Are opposed to each other (counter electrode arrangement), and the relative phase between the inner circumferential rotor and the outer circumferential rotor becomes a field weakening phase.

  Of the relative phases of the inner rotor and the outer rotor, the intermediate phase between the strong field phase and the weak field phase is the difference between the inner permanent magnet and the outer permanent magnet. Even if a part (the part on the side toward the rotation direction) is arranged as a counter electrode, the other parts (a part on the side opposite to the rotation direction) are left in the same polarity arrangement state. At this time, in at least one of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet, the opposite side from the short side on the side facing the predetermined rotation direction (the side corresponding to the portion remaining in the same-pole arrangement state) By making the short side small, the portion of the magnetic flux remaining in the same-pole arrangement state is reduced, and the peak value of the induced voltage in the intermediate phase is lowered as compared with the strong field phase.

  As a result, the magnetic field weakening current in the intermediate phase can be reduced to reduce the copper loss, and the relationship between the phase and the induced voltage constant approaches a linearity, so that it is easy to estimate the induced voltage constant with respect to the phase. Can be easily controlled.

  As one aspect of the present invention, the inner peripheral side permanent magnet and the outer peripheral side permanent magnet are both formed into a wedge shape. In this case, it is preferable to arrange the inclined surfaces of the wedge shape so as to face each other in parallel.

  That is, the inner peripheral side permanent magnet and the outer peripheral side permanent magnet having a wedge shape have parallel inclined surfaces when facing each other in the strong field phase and the weak field phase. When the inner peripheral side permanent magnet and the outer peripheral side permanent magnet are displaced in a predetermined rotational direction, and the relative phase between the inner peripheral side rotor and the outer peripheral side rotor becomes an intermediate phase, the same polarity arrangement is used. The space between the inclined surfaces of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet of the portion remaining in this state is widened. As a result, the field magnetic flux can be sufficiently weakened in the portion where the same polarity arrangement of the intermediate phase remains, so that the peak value of the induced voltage of the intermediate phase can be reliably reduced as compared with the strong field phase. .

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a main part of an electric motor according to the present embodiment, FIG. 2 (a) is an explanatory diagram showing a strong field phase state of an inner rotor and an outer rotor, and FIG. (B) is explanatory drawing which shows the intermediate phase state of an inner peripheral side rotor and an outer peripheral side rotor, FIG.2 (c) is description which shows the field weakening phase state of an inner peripheral side rotor and an outer peripheral side rotor. FIG. 3 (a) is an explanatory view schematically showing the facing state of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet in the strong field phase, and FIG. 3 (b) is an inner peripheral side permanent magnet in the intermediate phase. FIG. 4 is an explanatory view schematically showing a state of facing the outer peripheral side permanent magnet, FIG. 4 is an explanatory view showing a relationship between the phase and the induced voltage in the present embodiment, and FIG. 5 is a phase and induced voltage in a comparative example for the present embodiment. It is explanatory drawing which shows these relationships.

  The electric motor 1 of the present embodiment is a so-called brushless DC motor, and as shown in FIG. 1, an annular outer peripheral rotor 2 and an inner peripheral rotor 3 disposed inside the outer peripheral rotor 2. And. The outer peripheral rotor 2 is connected to the rotary shaft 4 via a drive plate (not shown), and the inner peripheral rotor 3 is rotatably supported by the rotary shaft 4 so that the outer peripheral rotor 2 and the inner peripheral rotor are supported. 3 are arranged concentrically.

  The outer peripheral rotor 2 includes a plurality of outer peripheral permanent magnets 5 arranged along the circumferential direction. The inner circumferential rotor 3 includes a plurality of inner circumferential permanent magnets 6 arranged along the circumferential direction corresponding to the respective outer circumferential permanent magnets 5. Both the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 are formed in a substantially plate shape having a wedge shape, and as shown in the drawing, the respective long sides in the cross-sectional shape parallel to the rotation shaft 4 ( The inclined surfaces 5c and 6c) are disposed so as to face each other.

  The outer peripheral side permanent magnet 5 provided on the outer peripheral side rotor 2 is magnetized in the thickness direction (that is, the radial direction of the outer peripheral side rotor 2), and the adjacent outer peripheral side permanent magnets 5 have different magnetization directions. Arranged to be in the direction. That is, of the adjacent ones, one outer peripheral side permanent magnet 5 is provided so that the outer peripheral side is N pole, and the other outer peripheral side permanent magnet 5 is provided so that the outer peripheral side is S pole, and the outer peripheral side is N pole. The outer peripheral side permanent magnets 5 and the outer peripheral side permanent magnets 5 having S poles are alternately arranged in the circumferential direction.

  Similarly, the inner peripheral permanent magnet 6 provided on the inner peripheral rotor 3 is magnetized in the thickness direction (that is, the radial direction of the inner peripheral rotor 3). The adjacent inner peripheral permanent magnets 6 are arranged so that the magnetization directions are different from each other. That is, one of the inner peripheral permanent magnets 6 adjacent to each other is provided so that the outer peripheral side is an N pole, and the other inner peripheral permanent magnet 6 is provided so that the outer peripheral side is an S pole. The N-pole inner peripheral side permanent magnets 6 and the S-pole inner peripheral side permanent magnets 6 are alternately arranged in the circumferential direction.

  The rotating shaft 4 includes a restricting portion 7 protruding in the radial direction, and the inner circumferential rotor 3 is restricted within a predetermined rotation range by the restricting portion 7. As shown in FIG. 2A, the rotation range of the inner circumferential rotor 3 regulated by the regulating section 7 is the outer circumferential side of the inner circumferential permanent magnet 6 of the inner circumferential rotor 3 and the outer circumferential rotor 2. From the phase (strong field phase) where the permanent magnets 5 are arranged so as to face each other with different magnetic poles (same polarity arrangement), the intermediate phase shown in FIG. 2B is passed through to FIG. 2C. As shown, the inner circumference side permanent magnet 6 of the inner circumference side rotor 3 and the outer circumference side permanent magnet 5 of the outer circumference side rotor 2 are arranged so as to face each other with the same polarity magnetic poles (counter electrode arrangement). Up to the phase (field weakening phase). The inner circumferential rotor 3 is pivoted in the circumferential direction by an actuator (rotating means) (not shown), and the relative phase between the inner circumferential rotor 3 and the outer circumferential rotor 2 can be changed.

  Further, as shown in FIG. 1, the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 have a wedge shape as described above, but the inner peripheral side rotor 3 has a strong field phase. If the direction of changing the phase to the field weakening phase is the rotation direction of the inner rotor 3, the inner permanent magnet 6 has a shorter side 6 a on the side toward the rotation of the inner rotor 3. The short side 6b on the opposite side is made small, and the long side of one of the short sides 6a and 6b is made to be an inclined surface 6c. Further, the outer peripheral side permanent magnet 5 is arranged so that the short sides 5a and 5b are positioned in the opposite direction to the inner peripheral side permanent magnet 6, and formed with the size of both the short sides 5a and 5b. The long side inclined surface 5 c faces the inclined surface 6 c of the inner peripheral permanent magnet 6.

  A stator 8 having a plurality of phase stator windings (not shown) for generating a rotating magnetic field for rotating the outer rotor 2 and the inner rotor 3 is provided on the outer periphery of the outer rotor 2. It has been.

  The electric motor 1 of the present embodiment configured as described above is mounted as a drive source in a vehicle such as a hybrid vehicle or an electric vehicle, for example, and the rotating shaft 4 of the electric motor 1 is connected to an input shaft of a transmission (not shown). 1 is transmitted to drive wheels (not shown) of the vehicle via a transmission.

  When driving force is transmitted from the driving wheel side to the electric motor 1 during deceleration of the vehicle, the electric motor 1 functions as a generator to generate a so-called regenerative braking force, and the kinetic energy of the vehicle body is used as electric energy (regenerative energy). to recover. Further, for example, in a hybrid vehicle, the rotating shaft 4 of the electric motor 1 is connected to a crankshaft of an internal combustion engine (not shown), and the electric motor 1 is a generator even when the output of the internal combustion engine is transmitted to the electric motor 1. Function as a power generation energy.

  Next, the operation of the electric motor 1 of the present embodiment will be described with reference to FIGS. In addition, since the outer peripheral side rotor 2 and the inner peripheral side rotor 3 are annular as shown in FIG. 1, in the case where a part is shown as shown in FIGS. However, in FIG. 3 to FIG. 5, for the convenience of explanation, the outer peripheral side rotor 2 and the inner peripheral side rotor 3 are illustrated in a flat plate shape.

  FIG. 2A and FIG. 3A show a state in which the outer rotor 2 and the inner rotor 3 are in a strong field phase. In this state, the inner peripheral side permanent magnet 6 is opposed to the outer peripheral side permanent magnet 5 by the magnetic poles having different polarities (having the same polarity arrangement), so that the inner peripheral side permanent magnet 6 generates a magnetic flux of the outer peripheral side permanent magnet 5. Strengthened. Then, a waveform A of the induced voltage at the strong field phase as shown in FIG. 4 is obtained, and the peak value Ap becomes relatively high.

  When the inner peripheral rotor 3 is rotated, the inner peripheral permanent magnet 6 is displaced with respect to the outer peripheral permanent magnet 5 as shown in FIGS. Become. In this state, the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 are opposed to each other with the magnetic poles having different polarities (having the same polarity arrangement). Are wedge-shaped, and the inclined surfaces 5c and 6c face each other in parallel, so that the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 in the strong field phase shown in FIG. Compared with the facing distance L1 of FIG. 3B, the facing distance L2 between the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 in the intermediate phase shown in FIG. As a result, the strong state of the magnetic flux of the outer peripheral side permanent magnet 5 by the inner peripheral side permanent magnet 6 can be suppressed, so that an induced voltage waveform B at an intermediate phase as shown in FIG. 4 is obtained, and its peak value Bp Is lower than the peak value Ap of the strong field phase.

  Here, if a comparative example with this embodiment is given, as shown in FIG. 5, the outer peripheral side permanent magnet 5 ′ and the inner peripheral side permanent magnet 6 ′ are not plate-shaped but a simple plate shape, Since the magnetic flux remains in an intensified state in the portion having the same polarity arrangement as the side permanent magnet 5 ′ and the inner peripheral side permanent magnet 6 ′, the peak value Ep in the waveform E of the induced voltage in the intermediate phase is a strong field magnet. It becomes as high as the peak value Dp in the waveform D of the induced voltage at the phase.

  On the other hand, in the present embodiment, as shown in FIG. 4, the peak value Bp in the waveform B of the induced voltage in the intermediate phase is lower than the peak value Ap in the strong field phase. It is possible to reduce the copper loss by reducing the weakening current.

  Thereafter, when the inner peripheral rotor 3 is further rotated, the inner peripheral permanent magnet 6 is opposed to the outer peripheral permanent magnet 5 as shown in FIG. In this state, the inner peripheral side permanent magnet 6 is opposed to the outer peripheral side permanent magnet 5 with the same magnetic pole (the counter electrode is disposed), so that the inner peripheral side permanent magnet 6 weakens the magnetic flux of the outer peripheral side permanent magnet 5. It is done. At this time, the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 face each other at the same interval as the facing interval L1 shown in FIG. The waveform C of the induced voltage at the field weakening phase as shown in FIG. 4 is sufficiently weakened.

  Thus, according to the present embodiment, the peak value Bp in the waveform B of the induced voltage in the intermediate phase can be lowered as shown in FIG. As a result, the relationship between the relative phase of the outer rotor 2 and the inner rotor 3 and the induced voltage constant approaches a linearity, so that the induced voltage constant can be estimated relatively accurately. Operation control can be easily performed.

  In the present embodiment, the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 are both wedge-shaped, and the inclined surfaces 5c and 6c thereof are opposed to each other. Although not limited to this, although not illustrated, only one of the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 is formed into a wedge shape, and the inclined surface of one wedge-shaped permanent magnet is used as the other permanent magnet. You may make it oppose.

Further, in the present embodiment, the outer peripheral side permanent magnet 5 and the inner peripheral side permanent magnet 6 are wedge-shaped, but the present invention is not limited thereto, and the shapes of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet are as follows. Any shape may be used as long as the short side opposite to the short side toward the rotation direction is smaller. For example, although not shown, a permanent magnet having a shape in which the thickness on the side toward the rotation direction is increased and the thickness on the opposite side is decreased through a step in the inner peripheral side permanent magnet and the outer peripheral side permanent magnet is employed. Alternatively, the sides provided with the steps may be arranged to face each other. In addition, this shape may be adopted only for either the outer peripheral permanent magnet or the inner peripheral permanent magnet. In this case, the side provided with the step of one permanent magnet faces the other permanent magnet. You can do it.

Explanatory drawing which shows schematic structure of the principal part of the electric motor which concerns on one Embodiment of this invention. Explanatory drawing which shows the state in each phase of an inner peripheral side rotor and an outer peripheral side rotor. Explanatory drawing which shows typically the opposing state of an inner peripheral side permanent magnet and an outer peripheral side permanent magnet. Explanatory drawing which shows the relationship between the phase and induced voltage in this embodiment. Explanatory drawing which shows the relationship between the phase and induced voltage in the comparative example with respect to this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Outer peripheral side rotor, 3 ... Inner peripheral side rotor, 4 ... Rotating shaft, 5 ... Outer peripheral side permanent magnet, 6 ... Inner peripheral side permanent magnet, 5c, 6c ... Long side (inclined surface), 5a, 5b, 6a, 6b ... short side.

Claims (2)

An outer periphery having an inner peripheral rotor having a plurality of substantially plate-like inner peripheral side permanent magnets arranged along the circumferential direction and a plurality of substantially plate-like outer peripheral side permanent magnets arranged along the circumferential direction A side rotor is disposed concentrically around the rotation axis, and at least one of the inner circumferential side rotor and the outer circumferential side rotor is rotated in the circumferential direction so that the inner circumferential side rotor and the An electric motor comprising rotating means for changing the relative phase between the outer rotor and the outer rotor,
The inner peripheral side permanent magnet and the outer peripheral side permanent magnet are arranged so that their long sides in a cross-sectional shape with respect to a direction parallel to the rotation axis face each other,
At least one of the inner peripheral side permanent magnet and the outer peripheral side permanent magnet is formed in a shape in which the short side on the opposite side is smaller than the short side on the side toward the predetermined rotation direction. Electric motor.   2. The electric motor according to claim 1, wherein the inner peripheral side permanent magnet and the outer peripheral side permanent magnet are both wedge-shaped, and are arranged such that their inclined surfaces face each other in parallel.

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