JPH0993846A - Permanent magnet type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in motor characteristics due to iron loss by providing air gaps between a permanent magnet and a nonmagnetic shaft and between the permanent magnet and adjacent laminated iron plate and nonmagnetic shaft and fixing a short circuit piece in the gap through a spring thereby increasing the current capacity in the constant torque region. SOLUTION: A nonmagnetic shaft is provided with a protrusion 1a which is secured, at the forward end thereof, with a laminated iron plate 2 split in the circumferential direction into four. A permanent magnet 3 is secured between the laminated iron plates 2 serving as poles such that the flux passes through adjacent poles. An air gap is provided on the inside (shaft 1 side) of permanent magnet 3 and a short circuit piece 4 is set in the air gap while being supported by a spring 5 movably in the radial direction. When the r.p.m. is low, the spring 5 is left in extended state and thereby the leakage flux ϕ2 is low and the main flux ϕ1 is relatively high. When the r.p.m. increases, a centrifugal force acts while resisting against the spring 5 and the short circuit piece 4 approaches the laminated iron plate 2 to increase the leakage flux ϕ2 thus decreasing the main flux ϕ1 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type synchronous motor, and more particularly to a rotor structure for improving constant output operation characteristics.

[0002]

2. Description of the Related Art Generally, a permanent magnet type synchronous motor has a constant torque operating region and a constant output operating region for controlling a wide range of rotation speeds. As shown in FIG. Desirably, in constant output operation, it is desirable that the voltage and current are constant and the torque decreases in inverse proportion to the rotation speed. However, in the conventional permanent magnet synchronous motor, the generated voltage increases in proportion to the rotation speed as shown in FIG. 9, and the voltage does not become constant even in constant output operation. However, instead of this, the current for increasing the constant torque is increased, leading to an increase in the power supply capacity. That is, in the permanent magnet type synchronous motor, since the motor magnetic flux is generated by the permanent magnet, the power generation voltage increases regardless of the voltage applied to the stator. Since the electric motor cannot be operated unless the applied voltage is larger than the generated voltage, the voltage pattern must be proportional to the rotation speed.

As a result, the current in the constant torque region becomes large, which causes an increase in cost and an increase in size of the equipment due to an increase in power supply capacity. Further, an increase in the thickness of the motor cable causes a decrease in workability and an increase in cost. . Furthermore, the characteristics of the motor deteriorate in the high speed range, that is, the iron loss is proportional to the square of the magnetic flux and to the 1.6th power of the frequency proportional to the rotation speed, and the efficiency based on the increase of the iron loss is increased. Bring about a decline. In the high speed region of constant output operation, the magnetic flux amount is reduced to suppress the increase of iron loss, but the deterioration of characteristics cannot be ignored.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a permanent magnet type synchronous motor which suppresses an increase in current capacity in a constant torque region, reduces the thickness of a motor cable, and reduces characteristic deterioration due to iron loss of the motor. To do.

[0005]

The present invention which achieves the above object is characterized by the following constitution. (1) A plurality of laminated iron plates are circumferentially divided and arranged on the outer periphery of a non-magnetic shaft, and permanent magnets are provided between the laminated iron plates along the circumferential direction. The permanent magnet is provided between the non-magnetic shaft and the permanent magnet. It is characterized in that a gap is provided between the laminated iron plate adjacent to the magnet and the non-magnetic shaft, and a short-circuit piece is mounted in the gap via a spring. (2) A plurality of laminated iron plates are arranged on the outer circumference of the shaft in the circumferential direction, a recess is formed along the circumferential direction on the shaft side of the laminated iron plate, and a spring is interposed in the recess to fit into the recess. It is characterized in that a slide piece having matching convex portions is divided into a plurality of pieces in the circumferential direction on the shaft side of the laminated iron plate, and a permanent magnet is arranged on the shaft side of the slide piece. (3) A permanent magnet is provided on the outer circumference of the shaft, and a plurality of laminated iron plates divided in the circumferential direction are arranged outside the shaft corresponding to the permanent magnet, and a short circuit is provided between the laminated iron plates divided in the circumferential direction via a spring. It is characterized in that the pieces are arranged so as to be movable in the radial direction. (4) A permanent magnet is provided on the outer circumference of the shaft, laminated iron plates are arranged on both sides of the permanent magnet, and a notch is provided at the center along the circumferential direction of the laminated iron plate, and a deformable magnetic material that can enter the notch. It is characterized in that a fluid is arranged.

The high-speed rotation causes the magnetic flux of the permanent magnet to pass through the short-circuiting piece or the magnetic fluid, which greatly reduces the main magnetic flux, so that the increase in the generated voltage can be adjusted.

[0007]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will now be described with reference to FIGS. 1 to 7 and 10. FIG. 1 is a configuration diagram showing an example, and FIG. 1 is a diagram showing an upper half of a four-pole rotor of an electric motor. In FIG. 1, a shaft 1 made of a non-magnetic material is provided with a protrusion 1a, and a laminated iron plate 2 is fixed to the tip of the protrusion 1a by being divided into four along the circumferential direction.
Permanent magnets 3 are fixedly interposed between the laminated iron plates 2 serving as magnetic poles so that magnetic flux passes through adjacent magnetic poles. Permanent magnet 3
Has an air gap inside (the shaft side), and the short-circuit piece 4 is provided in the air gap so as to be movable in the radial direction. That is, the short-circuit piece 4 is supported by the spring 5 over the adjacent laminated iron plates 2 centering around the permanent magnet 3, and has a ferromagnetic material. In this case, the spring 5 is made of a non-magnetic material.

FIG. 1 (b) is an enlarged view of FIG. 1 (a). The magnetic flux generated from the permanent magnet 3 is composed of the main magnetic flux φ ₁ and the leakage magnetic flux φ ₂ , but in the state where the rotation speed is low. Since the short-circuit piece 4 is separated by the spring 5, the leakage magnetic flux φ ₂ is small. On the other hand, when the rotation speed increases and the spring 5 contracts and the short-circuit piece 4 approaches by the centrifugal force, the main magnetic flux φ ₁ decreases and the leakage magnetic flux φ ₂ increases. Then, when the short-circuit piece 4 contacts the laminated iron plate 2, the main magnetic flux φ ₁ disappears. Further, when the rotation speed is lowered, the short-circuit piece 4 is separated by the force of the spring 5 and the main magnetic flux φ ₁ is increased. In this way, the main magnetic flux is reduced or restored according to the change in the rotation speed, and the generated voltage can be adjusted.

FIG. 2 shows another example. In FIG. 2, FIG.
The same parts as those in FIG. FIG. 2A is a cross section along the axial direction, in which a laminated iron plate 2 made of a silicon steel plate and a stainless steel plate 6 are alternately laminated on the shaft 1 along the axial direction. In this case, the stainless steel plate 6 is fixed to the shaft 1, and the laminated iron plate 2 has a space as shown in FIGS. 2 (c) and 2 (d). And
The laminated iron plate 2 and the stainless steel plate 6 are penetrated by the damper 7, and the laminated iron plate 2 is supported and fixed by the stainless steel plate 6. In addition, the laminated iron plate 2 is 4 along the circumferential direction.
It is divided, and a permanent magnet 3 is fixedly interposed between the laminated iron plates 2 as in FIG. Further, the short-circuit piece 4 is supported and fixed by a spring 5 so as to straddle the laminated iron plates 2 adjacent to each other in the void inside the permanent magnet 3. This short-circuit piece 4
2 has a structure as shown in FIG. 2B, has a width similar to that of the laminated iron plate 2 sandwiched by the stainless plates 6, has a receiving groove 4a for the spring 5, and slides the stainless plate 6. It has a protrusion 4b that fits in the guide groove 6a. Therefore, when the short-circuit piece 4 is supported by the spring 5 and the projection 4b is fitted in the slide guide groove 6a of the stainless plate 6, the short-circuit piece 4 can slide in the groove of the slide guide groove 6a. When the number of rotations is low, the spring 5 remains stretched, the leakage magnetic flux is small, and the main magnetic flux is relatively large. On the other hand, when the rotation speed increases, centrifugal force acts against the spring 5,
The short-circuit piece 4 approaches the laminated iron plate 2 and the main magnetic flux decreases as the leakage magnetic flux increases. In this way, the main magnetic flux can be increased / decreased as well as the rotation speed, and the generated voltage can be adjusted.

FIG. 3 shows a third example of the present invention. In this example, a laminated iron plate 2 having a space is attached to a shaft 1 which is a ferromagnetic body by being divided into four in a circumferential direction.
Recesses 2 a are formed in the circumferential direction at a plurality of positions along the axial direction of the laminated iron plate 2. On the other hand, this laminated iron plate 2
The convex portion 8a of the slide piece 8 is formed and fitted to the concave portion 2a. The slide piece 8 is provided corresponding to the laminated iron plate 2, and the permanent magnet 3 is fixed to the inside (shaft side) thereof. The slide piece 8 and the permanent magnet 3 are supported by the convex portion 8a by the spring 5 located in the concave portion 2a. When the rotor is stationary in such a state, the spring 5 expands and the slide piece 8 and the permanent magnet 3 shift toward the shaft side, so that the slide piece 8 and the concave portion 2a and the convex portion 8a of the laminated iron plate 2 are engaged with each other. The number of joints is reduced, the gap between the permanent magnet 3 and the shaft 1 is reduced, and the permanent magnet 3 and the shaft 1 are brought into contact with each other to reduce magnetic resistance. As the rotor rotates at a higher speed, the convex portion 8a enters into the concave portion 2a against the spring 5 due to the centrifugal force, the gap between the permanent magnet 3 and the shaft 1 increases, and the magnetic resistance increases. Main magnetic flux laminated iron plate 2
The amount passing through is reduced and the main magnetic flux is reduced. In this way, the main magnetic flux can be adjusted, and the generated voltage can be adjusted.

FIG. 4 shows a fourth example of the present invention, in which the outer circumference of the shaft 1 is divided into four parts and the permanent magnets 3 are fixed to each other, and the laminated iron plate 2 is arranged on the permanent magnets 3. In this case, a non-magnetic stopper 9 is interposed and fixed on the outer peripheral portion between the adjacent laminated iron plates 2, and a non-magnetic slide piece 10 is fixed to the end of the laminated iron plates 2 on the permanent magnet 3 side. One end of the spring 5 is fixed to the non-magnetic stopper 9, and a short-circuit piece 11 is fixed to the other end of the spring 5. The short-circuit piece 11 can slide between the non-magnetic slide pieces 10 and between the laminated iron plates 2, and can move between the shaft 1 and the non-magnetic stopper 9. When the rotation speed is low, the non-magnetic slide piece 10 is stretched by the expansion of the spring 5.
The short-circuiting piece 11 is located in between, and the main magnetic flux is formed without the magnetic flux from the permanent magnet 3 leaking. On the other hand, as shown in FIG. 4B, at a high rotation speed, the short-circuit piece 11 is biased toward the non-magnetic stopper 9 side against the centrifugal force and the leakage of the main magnetic flux increases.
Therefore, the main magnetic flux is reduced and the generated voltage can be adjusted. In this example, the short-circuit piece 11 moves in the gap between the laminated iron plates 2, and therefore the spring 5 is weaker than the embodiment shown in FIGS. It can be done with a certain amount of power. In addition, in the example of FIGS.
~ 5th power is required.

The equivalent circuit of the magnetic circuit has the structure shown in FIG. 5, and in each of the examples shown in FIGS. 1 to 4, the constant magnetic flux generated by the magnet is the main magnetic flux of the resistance R _{o and} the resistance R _x determined by the movement of the shorting piece. It consists of leakage magnetic flux, and the resistance R _x is about 10 times R _o when the rotating machine is stopped. In this case, a force proportional to the square of the number of revolutions acts on the short-circuiting piece that causes a change in the resistance R _x , so a spring force corresponding to the force is required. Moreover, the spring force must be proportional to the fourth power to the fifth power with respect to the displacement.
That is, while the rotational speed is low, the displacement of the short-circuit piece is large and the displacement amount is reduced as the rotational speed is increased, whereby the voltage curve of FIG. 7 is obtained. The characteristic of FIG. 7 is that the generated voltage increases with rotation, but a preload section may be provided as a constant torque range, and the short-circuit piece starts moving at a certain number of rotations as shown in FIG. 6B. Thus, in the example of FIG. 4, the short-circuit piece 11 may be pressed against the shaft 1 as shown in FIG. 6A so that the short-circuit piece does not move until then. Although each of the above-described embodiments has been described on the premise of a rotor having a four-pole structure, the number of poles is not limited to four.

Further, FIG. 10 shows another example,
Permanent magnets 3 are equidistantly arranged on the outer circumference of the shaft, and a laminated iron plate 2 is provided between the permanent magnets 3. Then, the laminated iron plate 2 is provided with a notch so as to divide the laminated iron plate 2 in the circumferential direction, and the non-magnetic storage case 20 is arranged in the notch. A deformable container 21 made of, for example, an elastic material such as rubber is communicated with the opening end of the non-magnetic storage case 20, and the case 20 and the container 21 form a hermetically sealed container. Air or a gas such as an inert gas is sealed at the tip (outer peripheral side of the motor) of the hermetically sealed container, and the separator 22
Deformation container 21 which is the base end (inner peripheral side of the motor)
In this case, the magnetic fluid 23 is enclosed, and in this case, the separator 22 is an airtight member capable of smoothly moving in the case 20 for separating the gas and the magnetic fluid 23. Then, the pressure when the gas is sealed is reversed 180 ° from the position of FIG. 10A and the posture is reversed, and even if the weight of the magnetic fluid 23 is added to the gas, only the weight is Then, the amount (pressure) is such that the gas does not contract.

In this structure, the centrifugal force increases as the rotation speed increases, and the magnetic fluid 23 compresses the gas. Therefore, the magnetic fluid 23 enters the laminated iron plate 2 by the compressed amount, and the magnet 3 short-circuits the magnetic circuit.
Reduces the magnetic flux emitted from the rotor surface. Then, as the speed becomes higher, the magnetic fluid 23 pressurizes the gas, the magnetic resistance between the magnets 3 decreases, the leakage magnetic flux increases, and the characteristics shown in FIG. 7 are obtained.

[0015]

As described above, according to the present invention, it is possible to obtain a nearly ideal constant output characteristic by adjusting the power generation voltage, and it is possible to reduce the power supply capacity with a decrease in the current and also to use the motor cable. The motor characteristics can be improved by reducing the iron loss. Further, the maximum value of the motor torque is determined by the size of the rotor and its surface magnetic flux density, but the size of the rotor does not change even if the short-circuit piece is built in, and as a result, the motor size does not change. Further, it is possible to support various kinds of constant output specifications depending on the strength of the spring and the configuration of the magnetic pole pieces. For example, the ratio between the constant torque range and the constant output range is 1: 1.
To about 1: 6, and in the constant output characteristic, the output torque may be inversely proportional to the 0.8th power, not inversely proportional to the rotation speed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of the present invention.

FIG. 2 is a configuration diagram of another example of the present invention.

FIG. 3 is a configuration diagram of a third example of the present invention.

FIG. 4 is a configuration diagram of a fourth example of the present invention.

FIG. 5 is an equivalent circuit diagram of a magnetic circuit.

FIG. 6 is an explanatory diagram showing other characteristics.

FIG. 7 is a characteristic curve diagram according to the present invention.

FIG. 8 is a characteristic curve diagram of an ideal voltage / current pattern.

FIG. 9 is a conventional characteristic curve diagram.

FIG. 10 is a configuration diagram of a fifth example of the present invention.

[Explanation of symbols]

 1 Shaft 1a Protrusion 2 Laminated iron plate 2a Recess 3 Permanent magnet 4,11 Short-circuit piece 4a Spring receiving groove 4b Protrusion 5 Spring 6 Stainless steel plate 6a Slide guide groove 7 Damper 8 Slide piece 8a Convex portion 9 Non-magnetic stopper 10 Non-magnetic slide piece 20 Non-magnetic storage case 21 Deformation container 22 Separator 23 Magnetic fluid

Claims (4)

[Claims] 1. A non-magnetic shaft is provided with a plurality of laminated iron plates divided in the circumferential direction, the permanent magnets are provided between the laminated iron plates along the circumferential direction, and between the permanent magnet and the non-magnetic shaft. A permanent magnet synchronous motor in which a gap is provided between the laminated iron plate adjacent to the permanent magnet and the non-magnetic shaft, and a short-circuit piece is mounted in the gap via a spring. 2. A laminated iron plate is circumferentially divided into a plurality of parts on the outer circumference of a shaft, and a concave portion is formed on the shaft side of the laminated iron plate along the circumferential direction. A spring is interposed in the concave portion.
A permanent magnet synchronous motor in which a slide piece having a convex portion that fits into this concave portion is circumferentially divided into a plurality of pieces on the shaft side of the laminated iron plate, and a permanent magnet is arranged on the shaft side of the slide piece. 3. A permanent magnet is provided on the outer periphery of the shaft, and further, a plurality of laminated iron plates divided in the circumferential direction are arranged outside the shaft corresponding to the permanent magnet, and a spring is interposed between the laminated iron plates divided in the circumferential direction. A permanent magnet type synchronous motor in which the short-circuit piece is arranged so as to be movable in the radial direction. 4. A deformable magnet which is provided with a permanent magnet on the outer circumference of the shaft, further has laminated iron plates arranged on both sides of the permanent magnet, has a notch at the center along the circumferential direction of the laminated iron plate, and can be inserted into the notch. Permanent magnet synchronous motor with various magnetic fluids.