JP2000316241A - Motor with embedded permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make flux uniform when controlling weakening flux, to suppress generation of a high voltage, to decrease a terminal voltage according to the increase of the weakening flux, by providing two or four recessed parts per pole between one or both of permanent magnets where a rotor is divided into two layers and the outer-periphery part of the rotor. SOLUTION: Two recessed parts 7 per pole are provided between both edges 1a of a permanent magnet 1 at an outer-periphery side and an outer-periphery part 3b of a rotor. The recessed part 7 is positioned inside in a radial direction as compared with the outer-periphery part 3b, has an arcuate part 9 and an inclined part 8, and shows the section shape of a mortar as a whole. Since the recessed part 7 increases the substantial air gap being seen from a stator 5, steep gap flux is decreased, and the inclined part 8 especially contributes to smooth decrease, thus preventing flux from greatly fluctuating even a weakening flux current is increased, uniformly making the flux weak, suppressing generation of a high voltage, and decreasing a terminal voltage according to the increase of the weakening flux current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved permanent magnet embedded motor having a rotor having a permanent magnet embedded inside the rotor and a stator having a concentrated winding coil.

[0002]

2. Description of the Related Art The technology of a conventional permanent magnet embedded motor is disclosed in Japanese Patent No. 2823817. The prior art shown in FIG. 6 discloses a rotor shape for generating a higher torque by effectively utilizing a magnet torque and a reluctance torque. Referring to FIG. 6, the configuration of this conventional technique will be described.

The rotor 3 has a rotor core 3a made of a high magnetic permeability material.
A permanent magnet of four poles, in which N poles and S poles are alternately arranged, is embedded and fixed to the rotor shaft 4. The number of permanent magnets per pole is 2 in the radial direction of the rotor.
It is divided into an outer peripheral side permanent magnet 1 and an inner peripheral side permanent magnet 2. Each of the permanent magnets 1 and 2 is formed in a circular arc shape protruding toward the center of the rotor, and has both end portions 1a and 2a.
Extend to a position close to the outer periphery of the rotor. The interval between the outer peripheral side permanent magnet 1 and the inner peripheral side permanent magnet 2 has a substantially constant width. A magnetic flux passage 10 through which the magnetic flux in the q-axis direction passes is formed in the space.

[0004] The stator 5 includes a predetermined number of teeth 6, and a stator coil (not shown) is arranged between the teeth 6. When an alternating current is applied to the stator coil, a rotating magnetic flux is generated, and a magnet torque and a reluctance torque act on the rotor 3 by the rotating magnetic flux, so that the rotor 3 is driven to rotate.

In order to construct the conventional permanent magnet embedded motor described above at a small size and at low cost, the stator coil (not shown) of the stator 5 may be a concentrated winding coil. The concentrated winding coil means that a U-phase stator coil is arranged with the teeth 6 of the stator 5 interposed therebetween, a V-phase stator coil is arranged with the adjacent teeth 6 interposed therebetween, and a W-phase stator coil is arranged with the adjacent teeth 6 interposed therebetween. This is a type of winding of the stator coil in which the stator coil is arranged.

When using a permanent magnet embedded motor, flux weakening control is generally used. The terminal voltage of a permanent magnet embedded motor increases with speed. The embedded permanent magnet motor cannot operate in a region where the terminal voltage is higher than the power supply voltage. Flux-weakening control is generally used to extend the speed control range of a permanent magnet embedded motor. The magnetic flux weakening control is a control in which the main magnetic flux of the permanent magnet embedded type motor is weakened. Specifically, utilizing the demagnetizing action due to the d-axis stator reaction,
This is control to reduce the gap magnetic flux.

[0007]

However, if the stator coil (not shown) of the stator 5 of the conventional permanent magnet embedded motor described above is a concentrated winding coil and the magnetic flux weakening control is used, the following problem occurs. .

FIG. 7 shows the rotor position on the horizontal axis and the magnitude of the magnetic flux on the vertical axis, and for each magnitude of the weak magnetic flux current (0 A, 40 A).
A, 80A, 120A. FIG. 6 is a diagram showing the magnitude of magnetic flux with respect to the rotor position of the same). From FIG. 7, it can be seen that even if the magnitude of the weak magnetic flux current increases, the magnetic flux is locally weakened and cannot be uniformly weakened. FIG. 8 is a diagram showing the magnitude of the terminal voltage with respect to the rotor position for each magnitude of the magnetic flux weakening, with the horizontal axis representing the rotor position and the vertical axis representing the terminal voltage. From FIG. 8, it can be seen that a local high voltage is generated due to a steep magnetic flux variation that occurs as the magnitude of the flux-weakening current increases. This is an inevitable result because the voltage is affected by the value obtained by differentiating the magnetic flux. FIG. 5 shows the magnetic flux weakening current on the horizontal axis and the terminal voltage on the vertical axis, and shows the magnitude of the terminal voltage with respect to the magnetic flux weakening current when there is no recess (prior art) and when there is a recess (one embodiment of the present invention). FIG. From FIG. 5, it can be seen that in the case of no concave portion (prior art), even if the magnitude of the magnetic flux weakening current is increased, the terminal voltage increases rather than decreases. When the terminal voltage increases in this way, there is a problem that the speed control range cannot be expanded.

In order to solve the above-mentioned problems, the present invention makes the magnetic flux uniform at the time of the magnetic flux weakening control, suppresses the generation of high voltage,
It is an object of the present invention to provide a permanent magnet embedded motor that can reduce a terminal voltage according to an increase in a magnetic flux weakening current.

[0010]

In order to achieve the above object, the invention of claim 1 comprises a rotor and a concentrated winding coil in which permanent magnets divided into two layers and arranged in a U-shape are embedded. In the motor with embedded permanent magnets having a stator having the same, the rotor has two poles per pole between one or both of the permanent magnets divided into two layers and the outer periphery of the rotor.
A permanent magnet embedded motor characterized by having four or four recesses.

According to another aspect of the present invention, there is provided a permanent magnet including a rotor having a permanent magnet embedded therein and divided into two layers and arranged in a U-shape, and a stator having a concentrated winding coil. In the motor with embedded magnets, the rotor is provided with two concave portions per pole between the permanent magnet and the outer peripheral portion of the layer near the outer peripheral portion of the rotor. .

According to a third aspect of the present invention, there is provided a permanent magnet embedded motor according to the first or second aspect, wherein the concave portion is located radially inward of an outer peripheral portion of the rotor in a circumferential direction. A permanent magnet embedded motor having an arc portion extending along the arc and an inclined portion extending from the arc portion to the outer peripheral portion of the rotor.

According to a fourth aspect of the present invention, there is provided a permanent-magnet embedded motor according to the first or second aspect, wherein the permanent magnets extend in a circumferential direction. An embedded permanent magnet motor comprising a radial permanent magnet extending from the vicinity of both ends of the circumferential permanent magnet to the outer periphery of the rotor.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The rotor 3 has a rotor core 3a made of a high magnetic permeability material.
8 permanent magnets 1, in which N poles and S poles are alternately arranged,
2 are embedded and fixed to the rotor shaft 4. The permanent magnet per pole is divided into two layers in the radial direction of the rotor,
An outer peripheral permanent magnet 1 and an inner peripheral permanent magnet 2 are provided.

Each of the permanent magnets 1 and 2 extends in the form of a plate-shaped circumferential permanent magnet 1c, 2c extending in the circumferential direction, and from the vicinity of both ends of the circumferential permanent magnets 1c, 2c to the outer periphery of the rotor. It is composed of plate-shaped radial permanent magnets 1b and 2b. Since both the circumferential permanent magnets 1c and 2c and the radial permanent magnets 1b and 2b are formed in a plate shape, there is no curved surface processing as compared with the case where the permanent magnets are formed in an arc shape as in the prior art. realizable. Further, the radial permanent magnets 1b, 2b and the circumferential permanent magnets 1c, 2c
The total occupation area can be set wider than the occupation area of the conventional arc-shaped permanent magnet, so that the magnetic flux can be increased, a larger magnet torque can be generated, and the magnet torque and the reluctance torque can be combined. Thus, an excellent effect that the combined torque can be further increased is exhibited.

The permanent magnets 1 and 2 are radial permanent magnets 1.
b, 2b and the circumferential permanent magnets 1c, 2c, they are U-shaped with respect to the rotor center side.

Both ends 1a, 2a of the radial permanent magnets 1b, 2b extend to positions near the rotor outer peripheral portion 3b. Two concave portions 7 are provided per pole between both end portions 1a of the outer peripheral side permanent magnet 1 and the rotor outer peripheral portion 3b. The concave portion 7 increases the substantial air gap as viewed from the stator 5 and reduces the gap magnetic flux. Although not shown, the concave portions are formed at both ends 2a of the inner peripheral side permanent magnet 2 and the outer peripheral portion 3b of the rotor.
May be provided with two concave portions per pole. Although not shown, the recess has two recesses per pole between both ends 1a of the outer peripheral permanent magnet 1 and the outer periphery 3b of the rotor, and further has both ends 2a of the inner permanent magnet 2 and the rotor. Two concave portions may be provided for one pole between the outer peripheral portion 3b. The location of the concave portion can be appropriately selected and designed depending on the degree of fluctuation of the magnetic flux, the state of increasing the terminal voltage, and the like.

A magnetic flux path 10 having a substantially constant width is provided between the outer peripheral permanent magnet 1 and the inner peripheral permanent magnet 2.
The magnetic flux passage 10 is formed so that a magnetic flux in the q-axis direction passes through the magnetic flux passage 10.

The stator 5 includes a stator core 5a and twelve teeth 6. A stator coil 5b composed of a U-phase winding, a V-phase winding, and a W-phase winding is arranged in a slot 5c between the teeth 6 in the form of a concentrated winding coil. When an alternating current is applied to the stator coil 5b, a rotating magnetic flux is generated.
, A magnet torque and a reluctance torque act to rotate the rotor 3.

The recess 7 will be described in detail with reference to FIG. The concave portion 7 has an arc portion 9 located radially inward from the rotor outer peripheral portion 3b and extending along the circumferential direction, and an inclined portion 8 extending from the arc portion 9 to the rotor outer peripheral portion 3b. It has the cross-sectional shape of a mortar. The arc portion 9 includes an arc shape and a straight shape.

The magnitude of the inclination of the inclined portion 8 can be appropriately selected and designed depending on the degree of fluctuation of the magnetic flux, the state of increasing the terminal voltage, and the like.

The concave portion 7 having such a shape increases the substantial air gap as viewed from the stator 5, and therefore reduces the steep gap magnetic flux. In particular, the inclined portion 8 contributes to a smooth reduction of the gap magnetic flux. Both end portions 1a of the outer peripheral permanent magnet 1 and the outer peripheral portion 3b of the rotor described with reference to FIGS.
The operation and effect of the embodiment of the present invention including the concave portion 7 provided between the first and second embodiments will be described below. (Not shown)
A concave portion provided between both ends 2a of the inner peripheral permanent magnet 2 and the rotor outer peripheral portion 3b, both ends 1a of the outer peripheral permanent magnet 1 (not shown) and both ends of the inner peripheral permanent magnet 2 In the case of the concave portions provided between the portion 2a and the rotor outer peripheral portion 3b, the same operation and effect are obtained, but the description is omitted.

FIG. 3 is a diagram showing the magnitude of the magnetic flux with respect to the rotor position for each magnitude of the flux-weakening current, taking the rotor position on the horizontal axis and the magnitude of the magnetic flux on the vertical axis, as in FIG. As is clear from FIG. 3, even when the magnitude of the weak magnetic flux current increases, the magnetic flux does not fluctuate greatly, and the magnetic flux can be weakened uniformly. FIG. 4 is a diagram showing the magnitude of the terminal voltage with respect to the rotor position for each magnitude of the flux-weakening current, with the horizontal axis representing the rotor position and the vertical axis representing the terminal voltage, as in FIG. From FIG. 4, it can be seen that even if the magnitude of the flux-weakening current becomes large, no steep magnetic flux fluctuation occurs, and no local high voltage is generated. FIG. 5 shows the magnetic flux weakening current on the horizontal axis and the terminal voltage on the vertical axis as described above, and no concave portion (prior art).
FIG. 8 is a diagram showing the magnitude of the terminal voltage with respect to the flux-weakening current in the case of (1) and in the case of the presence of the concave portion (one embodiment of the present invention). From FIG. 5, it can be seen that in the case where the concave portion 7 is provided (one embodiment of the present invention), the terminal voltage decreases when the magnitude of the magnetic flux weakening current is increased. When the terminal voltage is reduced in this manner, an excellent effect that the speed control range can be expanded is achieved.

[0024]

According to the present invention, there is provided a permanent-magnet embedded motor including a rotor having two layers and embedded with a permanent magnet embedded in a U-shape, and a stator having a concentrated winding coil. Between one or both of the permanent magnets divided into layers and the outer periphery of the rotor;
Since it is a permanent magnet embedded motor characterized by having four or four recesses, the magnetic flux is made uniform at the time of weak magnetic flux control, the generation of high voltage is suppressed, and the terminal voltage is increased according to the increase of the weak magnetic flux current. To reduce
An excellent effect that the speed control range can be expanded is achieved.

[Brief description of the drawings]

FIG. 1 shows a plan view of an embodiment of the present invention.

FIG. 2 shows a schematic view of a main part of an embodiment of the present invention.

FIG. 3 is a diagram showing the magnitude of magnetic flux with respect to the rotor position for each magnitude of the flux-weakening current, with the horizontal axis representing the rotor position and the vertical axis representing the magnitude of the magnetic flux in the embodiment of the present invention.

FIG. 4 is a diagram showing the magnitude of the terminal voltage with respect to the rotor position for each magnitude of the magnetic flux weakening, with the horizontal axis representing the rotor position and the vertical axis representing the terminal voltage in the embodiment of the present invention.

FIG. 5 shows the magnetic flux weakening current on the horizontal axis and the terminal voltage on the vertical axis,
The figure which showed the magnitude | size of the terminal voltage with respect to the magnetic flux weakening current in the case without a recessed part (prior art) and the case with a recessed part (1 embodiment of this invention) is shown.

FIG. 6 shows a plan view of an embodiment of the prior art.

FIG. 7 is a diagram showing the magnitude of magnetic flux with respect to the rotor position for each magnitude of weakening magnetic flux current, with the horizontal axis representing the rotor position and the vertical axis representing the magnitude of the magnetic flux in the prior art.

FIG. 8 is a diagram showing the magnitude of the terminal voltage with respect to the rotor position for each magnitude of the flux-weakening current, with the horizontal axis representing the rotor position and the vertical axis representing the terminal voltage for the prior art.

[Explanation of symbols]

 1 ... outer peripheral side permanent magnet, 1a ... both ends, 1b ... radial direction permanent magnet, 1c ... circumferential direction permanent magnet, 2 ... inner side permanent magnet, 3 ... rotor, 3a ... rotor core, 3b: rotor outer periphery, 4: rotor shaft, 5: stator, 5a: stator core, 5b: stator coil, 5c: slot, 6: teeth, 7: concave portion, 8: inclined portion, 9 ... arc part,

Claims (4)

[Claims] 1. A permanent magnet embedded motor comprising a rotor having two layers and embedded with permanent magnets arranged in a U-shape and a stator having concentrated winding coils.
A permanent magnet embedded motor, wherein the rotor is provided with two or four concave portions per pole between one or both of the permanent magnets divided into two layers and the outer periphery of the rotor. 2. A permanent magnet embedded motor having a rotor in which permanent magnets divided into two layers and arranged in a U shape are embedded and a stator having concentrated winding coils.
The permanent magnet embedded motor, wherein the rotor has two concave portions per pole between an outer peripheral side permanent magnet and the outer peripheral portion of the rotor. 3. The permanent magnet embedded motor according to claim 1, wherein the concave portion is located radially inward from the outer periphery of the rotor and extends along the circumferential direction. A permanent magnet embedded motor having an inclined portion extending around the outer periphery of the rotor. 4. The permanent magnet embedded motor according to claim 1, wherein the permanent magnet extends in a circumferential direction, and a circumferential permanent magnet extends from near both ends of the circumferential permanent magnet. A permanent magnet embedded motor comprising a radially extending permanent magnet.