KR101077593B1 - Switched reluctance motor having a structure for sensing the position of rotor with static magnetic field - Google Patents

Abstract

 The present invention relates to a switched reluctance motor having a rotor position detecting structure using a static magnetic field, which includes a stator fixed in a case 24 and a rotor rotating inside the stator to transmit power to the rotating shaft 20. In the switched reluctance motor 100, the center of the upper and outer sides of the case 24 is fixed to the rotating shaft 20, has a magnetic field shielding function, a plurality of mutually alternating magnetic field shielding along the edge An encoder 30 having a disc shape having a portion 35 and a magnetic field passing portion 37; One or more magnetic field generating means (40) fixedly installed at a position through which the magnetic field shielding portion (35) and the magnetic field passage portion (37) of the encoder (30) rotating on the top surface of the case (24); As the magnetic field shielding part 35 and the magnetic field passing part 37 of the encoder 30 which rotate in a position corresponding to the magnetic field generating means 40 pass, the magnetic field from the magnetic field generating means 40 is rained. And a magnetic sensor 50 fixedly installed to detect or detect. Accordingly, it is possible to provide a highly efficient switched reluctance motor that can be miniaturized and light in weight and minimizes the generation of back EMF.

Description

Switched Reluctance Motor Having A Structure for Sensing the Position of Rotor With Static Magnetic Field}

The present invention relates to a switched reluctance motor, and more particularly, by configuring the rotor position detection structure for motor control in a structure that shields a stationary magnetic field of a predetermined size from entering a desired space, which can be miniaturized and reduced in weight. A high efficiency switched reluctance motor having a rotor position detection structure using a new stationary magnetic field to minimize back EMF generation.

In general, a switched reluctance motor (SR motor) is a motor that uses only an in-core electromagnetic force (reluctance torque) in the configuration of a rotor (rotor) and a stator (stator). It is attracting attention as a next generation motor because of its high efficiency compared to an electric motor. The output torque in this SR motor acts in the direction of minimizing the reluctance of the magnetic circuit, and the direction of torque proportional to the square of the current is determined by the rate of change of inductance irrespective of the direction of supply current. Therefore, the torque of the SR motor can be controlled by appropriately adjusting the excitation current of the winding according to the position of the rotor. In fact, detecting the position of the rotor in an SR motor is essential for motor speed-torque control.

Generally, in the rotor position detection method of the SR motor, the most important point is that the pre-detection signal and the post-detection signal are output at the moment when the specific position of the rotor is detected, that is, immediately before and after the specific position is detected. It is to be separated. Most preferably, the signal output at that moment appears in the form of an ideal square wave that rises or falls at a right angle, such as a staircase.

To this end, as a sensing structure for detecting a rotor position of an SR motor, a disc-encoded disc-shaped encoder disk and an optical sensor are well known. 1 schematically shows this conventional SR motor 10 as a cross-sectional view cut vertically at its axis of rotation. The SR motor 10 has a rotating shaft 11 coupled to the object to be rotated to rotate the rotating object, a rotor 12 coupled to the rotating shaft 11 to provide rotational power, and the rotor 12 A stator 13 which allows rotation, and a case 14 fixedly coupled to the stator 13 and coupled to the rotor 12 via a bearing 16 and forming the entire or most exterior of the SR motor. It is composed. In addition, as a structure for detecting the position of the rotor 12 of the SR motor 10, a disc-shaped encoder disk 15 fixed to one end of the rotor 12 outside the case 14 and an optical sensor as a position sensor. (17) is provided. In the light emitting unit 17a and the light receiving unit 17b of the photosensor 17, the encoder disk 15 rotates as the rotor 12 rotates, so that light from the light emitting unit 17a is transmitted to the light receiving unit 17b. The position of the rotor 12 can be detected by the action of turning off or cutting off.

By the way, the rotor position detection structure using such an optical sensor has various problems. That is, the position where the optical sensor 17 and the encoder disk 15 are present has to be sealed with the light shielding function so that external light does not penetrate, and thus the manufacturing cost increases, and the size of the parts is relatively large. There was a disadvantage that the volume is unnecessarily large. Furthermore, even if blocked from the outside, there is a risk of malfunction when dust or foreign matter, which may be generated inside, is attached to the optical sensor 17, and when the optical sensor 17 is too close to the encoder disk 15, The encoder disk 15 may be displaced from its own rotation path by an external impact or the like and collide with the optical sensor 17, thereby increasing the risk of malfunction or failure. Furthermore, since the photosensitization sensitivity by the photosensor 17 is typically very sensitive, a change in the detection signal occurs in response to an error inevitably occurring when the encoder disc 15 is manufactured. Accordingly, the signal before and after detecting the specific position of the rotor does not change at right angles like a step, but shows a relatively gentle inclination, which makes it difficult to precisely control the motor and increases the counter electromotive force, which may cause a decrease in efficiency. Could.

Therefore, in the rotor position detection technology of the SR motor, there is still an urgent need for a structure that can reduce and reduce the rotor position detection structure for motor control and also minimize the generation of back EMF.

The present invention has been invented to improve and complement the rotor position detection technique of the conventional SR motor described above and to provide various additional advantages. According to the present invention, the rotor position detection structure for controlling the motor is configured to shield the static magnetic field of a certain size into a desired space so that a new static magnetic field can be miniaturized and reduced in weight, and the back electromotive force can be minimized. It is an object of the present invention to provide a highly efficient switched reluctance motor having a rotor position detection structure.

This object is achieved by a highly efficient switched reluctance motor having a rotor position detection structure utilizing a stationary magnetic field provided in accordance with the present invention.

A switched reluctance motor having a rotor position detecting structure using a static magnetic field provided according to an aspect of the present invention includes a switched reluctance having a stator fixed in a case and a rotor rotating inside the stator to transmit power to a rotating shaft. In the turn motor, a disk-shaped encoder having a center fixed to the rotation shaft at the inside and the outside of the case, having a magnetic shielding function, and having a plurality of mutually alternating magnetic shields and magnetic passages along its edges; ; One or more magnetic field generating means fixedly installed at a position passing by the magnetic field shielding portion and the magnetic field passing portion of the encoder rotating on the top surface of the case; The magnetic field shield and the magnetic field passing portion of the encoder rotates at a position corresponding to the magnetic field generating means may include a magnetic sensor fixed to detect or detect the magnetic field from the magnetic field generating means.

In one embodiment, the magnetic sensor is a hall sensor.

In another embodiment, the magnetic field generating means is embedded in the case so that only the upper surface thereof is exposed to the outside.

In another embodiment, the upper end of the case has a protrusion having a diameter similar to the diameter of the encoder around the axis of rotation and a recess formed outside the protrusion, the magnetic field generating means at the edge of the protrusion It is embedded, and the boundary between the protrusion and the recess forms a vertical plane in the form of a step.

In yet another embodiment, the magnetic field generating means is a permanent magnet.

A highly efficient switched reluctance motor having a rotor position detection structure using a stationary magnetic field according to the present invention having the above-described configuration is configured to shield a rotor position detection structure for motor control so that a stationary magnetic field of a predetermined size does not flow into a desired space. By constructing the structure, it can be miniaturized and reduced in weight and also provides the effect of minimizing the generation of back EMF.

1 is a schematic cross-sectional view showing the structure of a conventional SR motor.
Figure 2 is a schematic partial cross-sectional view showing a rotor position detection structure of the SR motor according to an embodiment of the present invention.
3 is a schematic plan view showing the rotor position detection structure of FIG. 2 in another direction;
4 is a schematic diagram showing in detail an example of an encoder disk according to an embodiment of the present invention.
5 is a graph illustrating an example of a rotor position detection signal in an SR motor according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings illustrating the present invention with a specific example as follows.

2 to 5 show a switched reluctance motor (SR motor) 100 provided in accordance with one embodiment of the present invention, which is an encoder 30 as a rotor position detection structure using a stationary magnetic field. And magnetic sensors 40 and 50.

Referring to FIG. 2, the SR motor 100 includes a stator (not shown) fixed in the case 24 and a rotor (not shown) that rotates inside the stator to transmit power to the rotating shaft, and the rotor has a rotating shaft ( 20 is fixed to the rotating shaft 20 is rotated in accordance with the rotation of the rotor. In the illustrated example, the SR motor 100 has an encoder 30, magnetic sensors 40 and 50, and a control board 60 installed outside the case 24, and has a cover 28 for protecting them from the outside. do. However, the present invention is not limited to the illustrated structure, and, for example, the size of the case 24 is made large enough to include the cover 28 and the encoder 30 and the magnetic inside the case 24 made so large. A configuration in which the sensors 40 and 50 and / or the control board 60 are installed is also possible.

SR motor 100 according to the present invention is characterized in that it has a sensing structure for detecting the rotational position of the rotor using a magnetic sensor in particular. Furthermore, the magnetic field detected by the magnetic sensor is in the form of a stationary magnetic field, and the magnetic sensor passes or is shielded by the magnetic field passing portion and the shielding portion formed in the rotating encoder, and thus the magnetic sensor detects the presence of the magnetic field. Has characteristics. The structure of the present invention may be regarded as detecting the relative position of the stator according to the rotation of the rotor, rather than directly detecting the position of the rotor.

The structure of detecting the position of the rotor in the SR motor 100 includes the encoder 30 and magnetic field generating means 40, 40A, 40B, 40C, which may be magnets, for example, and a hall sensor using a Hall effect, or It may be composed of a magnetic sensor 50 such as a Hall IC.

The center of the encoder 30 is fixed to the rotating shaft 20 which is rotated together with the center of the upper end of the case 24 fixed to the rotor. Although not shown in the drawings, the encoder 30 may have its center fixed to the rotating shaft 20 inside the case 24, in which case the size of the case 24 is larger than in the illustrated example. It should be constructed.

To this end, the encoder 30 has a magnetic field shield 35 in the form of an alternating protrusion-concave portion with an edge of the encoder body 31, which is a disk made of a thin metal plate having a fixing part 33 that can be fixed to the rotation shaft 20. ) And the magnetic field passing part 37. The most important function of the encoder 30 is the magnetic field shielding and passing function. In particular, the edge of encoder 30 has a number of alternating magnetic field shields 35 and magnetic field passages 37 along the edges, as clearly shown in FIGS. 3 and 4.

The shape of the magnetic field shield 35 and the magnetic field passing portion 37 is a concave-convex structure formed in succession to each other when viewed in a thin side in the illustrated embodiment, the magnetic field passage portion 37 is a C-shaped perforated structure in which one side is open. However, the present invention is not limited to this structure. Since the magnetic field passing portion 37 is sufficient to allow the magnetic field to pass therethrough, for example, the magnetic field passing portion 37 may be in the form of a circularly open opening surrounded by the magnetic field shield 35. In addition, in the illustrated example, the magnetic field passing part 37 is formed in a form in which the encoder body 31 is completely cut and drilled, but the present invention is not limited to such a drilled form. As an example of an embodiment having a different configuration, there may be a case where the encoder body 31 is made of a material having a low magnetic permeability, that is, a magnetic field shielding function, which is coated with a material of a high permeability such as metal. In such a case, since only the magnetic field shielding part 35 is coated with a high permeability material having a magnetic field shielding function, the magnetic field passing part 37 is a form in which only the high permeability coating is peeled off without having to pierce the encoder body 31. It can be configured as.

The magnetic field shielding effect of the magnetic field shield 35 is sufficient to block a DC magnetic field or a static magnetic field generated by the magnet from entering the desired space, that is, the sensing area of the magnetic sensor. It is well known that such a magnetic field shielding effect can be achieved by a material having a high permeability absorbing the magnetic field or changing the path of the magnetic field. Therefore, the magnetic field shield 35 according to the present invention, in its simple embodiment, is made of a thin metal plate having a high permeability of the encoder body 31, and then cuts between adjacent magnetic field shields 35 to pass through the magnetic field. Can be made by forming 37.

4 shows the shape of an encoder 30 having eight magnetic field passages 37 and eight magnetic field shields 35. The size of each magnetic field passing portion 37 and the magnetic field shield 35 has an angle of about 3: 2, but the size ratio of these is not limited to this embodiment, but the specification and size of the motor And other ratios are possible depending on the control purpose.

The magnetic field generating means may be made of a permanent magnet, that is, a magnet, and only one magnet 40 may be installed. However, as in the embodiment shown in FIGS. 3 and 4, in the case of a three-phase motor, three identical magnets ( 40A, 40B, and 40C may be fixedly installed at positions corresponding to three different stator windings. As such, matching the position and number of the stator windings with the required position and number of magnets, respectively, can further minimize back EMF and enable more precise torque control.

The magnetic field generating means, that is, the magnets 40, 40A, 40B, and 40C are fixedly installed on the top surface of the case 24. Since the upper end surface of the case 24 is coupled with the rotation shaft 20 via the bearing 26, the rotation shaft 20 rotates with respect to the upper surface of the case 24. Since the case 24 is coupled to the stator, the encoder 30 fixed to the rotation shaft 20 eventually rotates with respect to the stator. The smaller the distance between the position where the magnetic field generating means 40, 40A, 40B, 40C is attached and the position where the encoder 30 is fixed to the rotation shaft 20, the smaller the smaller. The position at which the magnets 40, 40A, 40B, and 40C are installed on the top surface of the case 24 corresponds to the position at which the magnetic field shield 35 and the magnetic field passing portion 37 pass as the encoder 30 rotates. It must be a location.

In order to prevent damage to the magnet that may occur when the encoder 30 rotates and vibrates by an external impact, the magnet 40 has a case 24 such that only the upper surface thereof is exposed to the outside as illustrated in FIG. 2. It is preferable to be embedded in the installation. In this case, the distance between the top surface of the case 24 and the encoder 30 is also provided with the advantage that it can be very narrow.

In another embodiment of the present invention, the upper end of the case 24 has a generally circular protrusion 24a having a diameter similar to the diameter of the encoder 30 about the rotation axis 20 from the case 24. It is preferable to protrude toward the encoder 30 side. A relatively low concave portion 24b is provided outside the protruding portion 24a. In this case, the magnets 40, 40A, 40B, and 40C may be embedded along the edge of the protrusion 24a. And it is preferable that the boundary between the protrusion part 24a and the concave part 24b forms a stepped vertical plane, not an oblique slope. This is because when magnets 40, 40A, 40B, and 40C are embedded or fixed in a case 24 made of a metal having a high permeability, the magnet periphery may be magnetized over time, and thus the magnetization of the surroundings It is possible to obtain an effect of reducing the effect of the portion on the magnetic sensor.

The magnetic sensor 50 is preferably a hall sensor that uses the Hall effect as an operation principle. Here, the Hall sensor detects the presence or absence of a magnetic field and can be used without limitation as long as the output signal (current / voltage) changes at almost right angles, such as stairs.

As in the illustrated embodiment, the magnetic sensor 50 is preferably provided below the control board 60 in which a circuit for controlling the SR motor 100 is configured. The control panel 60 is equipped with circuits that provide the appropriate voltage or current to the stator windings based on the signal output from the magnetic sensor 50, and has a fixed pin (10) apart from the top surface of the case 24. It may be fixed to the case 24 by the 24. The number and positions of the magnetic sensors 50 to be installed correspond to the numbers and positions of the magnets 40, 40A, 40B, and 40C to be installed.

The magnetic sensor 50 and the magnet 40 face up and down at positions corresponding to each other, and when there is nothing between them, the magnetic field generated from the magnet 40 may be detected by the magnetic sensor 50. . The encoder 30 rotates between the two, so that the magnetic field shielding part 35 and the magnetic field passing part 37 of the encoder 30 pass in turn.

Therefore, while the magnetic field shield 35 of the encoder 30 is between the magnetic sensor 50 and the magnet 40, the output of the magnetic sensor 50 becomes, for example, 0, and the magnetic field passage 37 becomes the magnetic sensor ( While between 50) and magnet 40, the output of magnetic sensor 50 may be, for example, one. Figure 5 shows the shape of the signal output by the three pairs of magnet-magnetic sensors A, B, C. The red portion of the graph shows that A detects a magnetic field from time t0 to t1, B detects a magnetic field from time t2 to t3, and C detects a magnetic field from time t4 to t5. have. As described above, A, B, and C operate independently while the time intervals for detecting the magnetic field and the time intervals for not detecting each have the same period, and precisely control the motor because the interface is close to the vertical when detecting each magnetic field detection. Becomes possible.

In the above, the present invention has been described through specific embodiments, but those skilled in the art can refer to and combine various features described in the present disclosure, and various and modified construction methods are possible. Therefore, it is intended that the scope of the present invention should not be limited to the described embodiments, but should be interpreted by the appended claims.

As described above, the present invention is particularly suitable for the field of a control motor requiring a relatively high rotational speed even by low power consumption, such as an electric vehicle or an electric bicycle, and in addition, it is widely used in fields requiring various high efficiency and high speed motors. It is possible.

100: SR motor
20:
22: bearing
24: case
24a: protrusion
24b: recess
26: fixed pin
28: cover
30: encoder
31: encoder body
33: rotating shaft fixing part
35 magnetic field shield
37: magnetic field passing part
40, 40A, 40B, 40C: Magnet (Magnet)
50: magnetic sensor
60: control board

Claims (5)

A stator fixed in the case 24 and a rotor rotating inside the stator to transmit power to the rotating shaft 20, the center of which is fixed to the rotating shaft 20 at the inside and outside of the upper end of the case 24. A disk-shaped encoder 30 having a magnetic field shielding function and having a plurality of mutually alternating magnetic field shielding portions 35 and magnetic field passing portions 37; Magnetic field generating means (40) fixedly installed at a position through which the magnetic field shielding portion (35) and the magnetic field passage portion (37) of the encoder (30) rotating on the top surface of the case (24); As the magnetic field shielding part 35 and the magnetic field passing part 37 of the encoder 30 which rotate in a position corresponding to the magnetic field generating means 40 pass, the magnetic field from the magnetic field generating means 40 is rained. In a switched reluctance motor 100 having a magnetic sensor 50 fixedly installed to detect or detect,
The upper end of the case 24 is provided with a protrusion 24a having a diameter similar to the diameter of the encoder 30 about the rotation shaft 20 and a recess 24b formed outside the protrusion 24a. The magnetic field generating means 40 is embedded in the edge portion of the protruding portion 24a, and the boundary between the protruding portion 24a and the concave portion 24b forms a stepped vertical surface. A switched reluctance motor having a rotor position detection structure using a magnetic field. delete delete delete delete

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