KR20100138163A - Detecting device for sensing the rotor position and brushless motor having the same - Google Patents

Abstract

PURPOSE: An apparatus for detecting the location of a rotor and a brushless motor including the same are provided to improve the location detecting precision of the rotor by generating the output wave of a sine wave directly from a sensor magnet. CONSTITUTION: A sensor magnet(110) is installed to the rotary shaft(31) of a rotor. The sensor magnet is composed of the combination of magnet units(111). A linear hole element(120) converts a sensing signal into an electric signal and outputs the electric signal to a controller. The linear hole element is arranged toward the circumference of the sensor magnet. The linear hole element generates the output wave of a sine wave using the sensing signal.

Description

Rotor position detection device and brushless motor having the same {DETECTING DEVICE FOR SENSING THE ROTOR POSITION AND BRUSHLESS MOTOR HAVING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and in particular, by implementing a sensor magnet in which a magnet piece magnetized in the axial direction is combined, the output of a sine wave comes directly from the sensor magnet. The present invention relates to a rotor position detection device and a brushless motor having the same, which simplify the configuration of a sensor, reduce the cost of a hall element, and maximize the position detection accuracy of the rotor and the control accuracy of the motor.

The brushless motor is a motor that removes mechanical contacts such as a brush and a commutator and implements this by an electronic commutator.

1 shows a drive system of such a brushless motor.

As shown in FIG. 1, a drive system of a brushless motor includes a converter 1, an inverter 2, a brushless motor 3 (hereinafter abbreviated as a motor), a controller 4 and a position detection. Device 10. The brushless motor 3 includes a stator wound with a coil and a rotor having a magnetic pole. The position detecting device 10 is installed inside the housing (or also referred to as a 'yoke') of the motor 3 to sense the position of the rotor. The controller 4 obtains the position and speed information of the rotor based on the sensing signal applied from the position detecting device 10 and compares it with the target speed and simultaneously compares the current value applied from the current sensor 5 with the target value. By generating an appropriate drive signal, and transmitting the drive signal to the inverter 4 to cause the inverter 4 to control the power required for the motor, the motor output torque is ultimately controlled so as not to deviate from the target value.

2 is a schematic cross-sectional view of a brushless motor showing an installation form of a conventional rotor position detection device.

As described above, the brushless motor 3 comprises a stator 20 as a stator with a coil wound thereon, and a rotor 30 as a rotor with a magnetic pole, ie, a magnet 31, on the rotation shaft 31. It includes.

The rotor position detecting device 10 mounts the sensor magnet 40 on the rotation shaft 31 of the rotor 30, and attaches a Hall Encoder 50 to the axial end surface of the sensor magnet 40. It is made to be mounted on the substrate 60 so as to face.

The Hall encoder 50 converts the sensing signal by the magnetic force emitted from the sensor magnet 40 into two electrical sine waves, that is, a sine wave and a cosine wave, and outputs the result. A sensor having a chip equipped with a Hall element (magnetic sensor), an amplifier, a modulator, and the like, which senses a magnetic force emitted from an axial end surface of the sensor magnet 40 and is proportional thereto. Outputs the voltage and converts the output voltage back to current and amplifies it to the controller.

As shown in FIG. 3, the sensor magnet 40 has a so-called 'radially-oriented' multipole magnet in which a magnetic field is formed in the axial direction. It is also called a multi-pole magnet).

A radially magnetized (or axial magnetic flux) sensor magnet is divided into a plurality of (mostly, two or four) imaginary magnet pieces 41 in the circumferential direction and polarities of adjacent magnet pieces 41 are separated from each other. The so-called 'radial orented' treatment was performed in different directions. That is, one magnet piece 41 magnetizes from the radially inner side to the outside, and the magnet piece 41 adjacent thereto magnetizes from the radially outer side to the inside. Alternatively, after separately providing single-pole magnets divided into four (or two-divided) forms in the circumferential direction, the adjacent magnet pieces 41 are alternately arranged in the circumferential direction such that polarities are opposite to each other.

The magnet piece 41 due to the radial magnetization emits a line of magnetic force around the end face (side face) 42 of the magnet piece 41 (to form a magnetic field), and accordingly, the hall encoder 50 The end face 42 of the sensor magnet 40 is disposed to face each other so that the magnetic force (magnetic force line) output from the sensor magnet 40 can be detected.

By the way, as described above, the radial magnetizing sensor magnet 40 is formed on the end surface 42 of one magnet piece 41 constituting the sensor magnet 40 uniformly the strength of the magnetic force over the entire circumferential section. do. Therefore, when the output waveform of the magnetic force emitted from the sensor magnet 40 is represented by a mechanical angle, as shown in the lower left of FIG. 3, a pulse wave is formed.

Therefore, the conventional rotor position detection device encounters a problem that when the sensor magnet 40 rotates, the Hall encoder 50 detects only the start point and the end point of the pulse wave (see the graph in the lower left of FIG. 3). Done. That is, only the inflection point portion by one magnet piece 41 and the magnet piece 41 adjacent thereto can be detected, but in the middle section between the start point and the end point of one magnet piece 41, Since there is no change, it is difficult to detect the rotation angle change amount. Therefore, the rotational position of the rotor can not be detected accurately, there is a closed end of less accurate motor control.

In addition, conventionally, the magnetic signal of the pulse wave emitted from the sensor magnet 40 (lower left graph in FIG. 3) is composed of two sinusoidal waves that are electrical signals, that is, a sine wave and a cosine wave (shown on the right side of FIG. 3). Since the circuit and the circuit configuration of the Hall encoder 50 are difficult and the unit price is high, they are not suitable for mass production or mass production motors.

The present invention has been invented to solve the above problems, by configuring the output of the sine wave directly from the sensor magnet, to facilitate the configuration of the sensor, reduce the cost of the sensor, the position detection accuracy of the rotor and the control precision of the motor An object of the present invention is to provide a rotor position detection device capable of maximizing and a brushless motor having the same.

In addition, the present invention is possible to increase or decrease the number of magnetic poles of the sensor magnet according to the use or type of the motor, even if the number of magnetic poles is easy to implement the sensor and does not significantly increase the price of the rotor position detection device and brushless having the same It is an object to provide a motor.

In order to achieve the above object, the rotor position detecting device according to the present invention is a rotor position detecting device for detecting a rotation position of the rotor in a motor including a stator and a rotor, the sensor magnet is installed on the rotating shaft of the rotor Become; A linear hall element which senses a magnetic force emitted from the sensor magnet, converts the sensing signal into an electrical signal and outputs it to a controller, is disposed toward the circumferential surface of the sensor magnet; The sensor magnet has a sinusoidal output wave due to the magnitude of the magnetic force detected from the outer circumferential direction in the path from one point in the circumferential direction to the circumference of the circumference and back to the starting point; The linear hall device generates a sinusoidal output wave required for a controller by using a sensing signal generated by a magnetic force detected from the circumferential direction of the sensor magnet.

Here, the sensor magnet is composed of a combination of magnet parts divided into two or more in the circumferential direction, wherein the magnetic force lines come out from one end surface in the axial direction by an axial magnetization process and are opposite ends via the circumferential part. Formed in the direction toward the side, the strength of the magnetic force detected in the circumference of each magnet portion is the largest in the middle portion of the circumference length and gradually decreases toward both sides of the circumferential direction, the adjacent magnets are set in the opposite direction to each other do.

In addition, the magnets may be configured in a form in which they are separately divided and manufactured.

The brushless motor according to the present invention includes a rotor position detection device comprising the above-described sensor magnet and hall sensor.

In the rotor position detecting device and the brushless motor according to the present invention, the sine wave outputs directly from the sensor magnet by magnetizing the sensor magnet in the axial direction, thereby facilitating the configuration of the hall sensor and reducing the cost of the hall sensor. Can be. In addition, it is possible to increase the position detection accuracy of the rotor and the control accuracy of the motor.

In addition, it is possible to facilitate the multi-pole axial magnetization of the sensor magnet by enabling the sensor magnet to be implemented in a combined form after the magnet piece divided in the circumferential direction in the axial direction.

In addition, since the number of magnetic poles of the sensor magnet and the number of Hall sensors are relatively free to increase and decrease, it can be manufactured in various forms according to the use or type of the motor.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 4 is a schematic diagram showing the configuration and sensing concept of the rotor position detection apparatus according to the present invention.

As shown in FIG. 4, the rotor position detecting apparatus 100 according to the present invention is directed toward the circumferential surface of the sensor magnet 110 and the sensor magnet 110 installed on the rotation shaft 31 of the rotor 30. One or more Linear Hall ICs 120 disposed therein. The sensor magnet 110 is formed of a multipole magnet, and the linear hall element 120 senses a magnetic force emitted from the sensor magnet 110 and outputs an analog waveform signal corresponding thereto.

The sensor magnet 110 is set so that the output waveform by the magnitude change of the magnetic force sensed outside the circumferential direction in the path from one point in the circumferential direction to the circumference of the circumference and back to the starting point is set to form a sine wave, The linear hall device 120 senses a change in the magnetic force emitted from the sensor magnet 110 (that is, the output wave of the sine wave) to generate an analog signal of the sine wave required for the controller.

That is, the strength of the magnetic force emitted from the circumferential surface of the sensor magnet 110 is configured to change continuously and regularly along the circumference of the sensor magnet 110, the intensity (magnitude) of the magnetic force emitted from the sensor magnet 110 ) Is connected to each point of the circumference to form a sine wave as shown in the graph (indicated by the machine angle) shown in the lower left of FIG. 4 so that the position (rotation angle) of the rotor can be detected accurately and easily. It is. In addition, the linear hall element 120 simply converts the sinusoidal magnetic signal emitted from the sensor magnet 110 into an electrical sinusoidal signal and outputs the linear hall element 120 simply and at low cost. It is possible to configure.

In the related art, the Hall encoder has to perform the operation of sensing the magnetic force emitted in the form of pulse wave in the sensor magnet and converting the magnetic force into two sinusoidal (sine and cosine wave) signals. Since it is detected as a sine wave, it must be taken as it is and converted into an electrical signal only.

The above-mentioned linear hall element 120 is composed of a simple configuration in which a single magnetic sine wave is simply output as a single electrical sine wave signal. In particular, as shown in FIG. 4, two linear hall elements having the same function are provided. If 120 is provided and arranged to maintain an electrical phase difference of 90 degrees from each other, one sine wave is output from each of the two linear hall elements 120, so that a total of two sine waves can be applied to the controller while maintaining the phase difference. .

In order for the present inventors to change the intensity of the magnetic force emitted from the sensor magnet 110 regularly along the circumference to emit the sine wave magnetic force, as shown in FIG. 4, the magnetizing direction of the sensor magnet 110 is called an axial direction. Experiments have shown that it is possible to use either Axially Orented or Axially Orented in Segment.

The axial magnetization of the sensor magnet 110 divides two or more cylindrical magnet materials in the circumferential direction, and has opposite polarities between the adjacent magnet parts 111 in the partitioned magnet parts 111. It can be achieved by magnetizing it.

By the way, in order to multi-magnetize a single-piece cylindrical magnet material, it is impossible to use a common magnetizer, and a special magnet (eg, Halbach magnetizer) must be performed by a specially manufactured magnetizer. The manufacturing cost and time of magnetizing yokes and magnets are excessively high, and it is difficult to maintain high maturity of the product.

Correspondingly, in addition to the method of axially multipolar magnetizing a single cylinder in the axial direction as described above, the cylindrical magnet material is axially magnetized in one direction to make a monopole magnet, and then divided into four equal parts to alternate polarities. Or assemble them so that they are opposite to each other, or physically pre-segment the cylindrical magnetic materials, and then uniaxially magnetize them in one direction while temporarily arranging them to make a monopole magnet, and then remove the temporarily assembled magnet pieces again. It can be easily manufactured by the method of arranging the polarities in opposite directions and rejoining them.

Of the above two methods, the latter method is briefly introduced through FIG. 5A.

As shown in FIG. 5A, the magnet pieces 111a to 111d are formed by dividing a single cylindrical material into two or more portions (for example, two equal parts, four equal parts, six equal parts, and eight equal parts). And axial magnetization is performed in a single direction in a state where the magnet pieces 111a are temporarily assembled.

Subsequently, the magnet pieces 111a to 111d which are temporarily assembled are separated again, and the polarities are alternately arranged in the opposite directions. That is, the first magnet 111a and the third magnet 111c facing each other in the diagonal direction may be easily reversed and finally assembled.

Alternatively, as shown in FIG. 5B, the magnet pieces that have already been divided are axially magnetized in parallel from the radially outer side to the inside, and the other divided magnet pieces are axially magnetized in parallel from the radially inner side to the outside. In this case, a combination of two magnet pieces may be used.

Referring back to FIG. 4, in the sensor magnet 110 of the present invention constituted by the above-described axial magnetization, a magnetic force line emerges from one end surface in the axial direction of the magnet part 111 by an axial magnetization process, thereby forming a circumferential portion. It is formed in the form facing the opposite end surface via. In addition, the strength of the magnetic force sensed at the circumference of each magnet portion 111 is the largest in the middle portion of the circumference length and gradually decreases toward both sides in the circumferential direction, and the adjacent magnet portions 111 have mutually different flow directions of the lines of magnetic force. They will be in opposite directions.

6A to 6C show the output waveforms when the rotor position detection device according to the present invention is arranged with different electrical phase differences.

As described above, the linear hall element 120 may be provided with one or more. The larger the number of the linear hall elements 120, the more the position can be subdivided and detected, thereby improving position detection accuracy and control accuracy. On the other hand, even if the number of divisions of the magnet piece is increased, the position detection accuracy and the control accuracy can be improved.

At this time, when there is one linear Hall element 120 (phase difference of 0 degrees), the waveform as shown in FIG. 6A is outputted. When two linear Hall elements 120 are arranged with an electrical phase difference of 90 degrees, the waveform as shown in FIG. When the two linear Hall elements 120 are disposed with an electrical phase difference of 180 degrees, a waveform as shown in FIG. 6C is output.

Next, FIG. 7 and FIG. 8 schematically show a brushless motor provided with a position detection device according to the present invention. The same parts as in FIG. 2 will be described with the same reference numerals.

As shown in FIGS. 7 and 8, the sensor magnet 110 is fixed on the rotation axis 310 of the rotor 30, and the linear hole element 120 faces the circumferential surface of the sensor magnet 110. It is arranged to maintain the electrical phase difference of 90 degrees in the state.

The linear hall element 120 is mounted on the printed circuit board 60 while being mounted on the support frame 125.

In the above, specific embodiments of the present invention shown in the accompanying drawings have been described in detail, but these are merely illustrative of the preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. In addition, the embodiments of the present invention as described above can be variously modified and equivalent other embodiments by those of ordinary skill in the art within the technical spirit of the present invention, such modifications and equivalent other embodiments are It belongs to the appended claims of the present invention.

1 is a circuit diagram showing a driving system of a general brushless motor.

2 is a schematic cross-sectional view of a brushless motor showing an installation form of a conventional rotor position detection device.

3 is a schematic diagram showing the configuration and sensing concept of a conventional rotor position detection device.

Figure 4 is a schematic diagram showing the configuration and sensing concept of the rotor position detection apparatus according to the present invention.

5A and 5B are diagrams showing an example of actually configuring a sensor magnet according to the present invention.

6A to 6C are views showing output waveforms when the rotor position detection apparatus according to the present invention is arranged with different electrical phase differences between the linear Hall elements.

7 is a sectional view schematically showing a brushless motor provided with a position detection device according to the present invention.

FIG. 8 is a side view of the sensor magnet and the linear hall element in FIG. 7. FIG.

Claims (5)

A rotor position detecting device for detecting a rotational position of the rotor in a motor including a stator and a rotor, The sensor magnet 110 is installed on the rotation shaft 31 of the rotor 30, A linear hall element 120 for sensing a magnetic force emitted from the sensor magnet 110, converting the sensing signal into an electrical signal and outputting the electrical signal to a controller is disposed toward the circumferential surface of the sensor magnet 110. The sensor magnet 110 is a sine wave of the output wave due to the magnitude of the magnetic force detected from the outer circumferential direction in the path from one point in the circumferential direction to the circumference of the circumference and back to the starting point, The linear Hall element (120) is a rotor position detection device, characterized in that for generating the output wave of the sine wave required for the controller by using the sensing signal of the magnetic force detected from the circumferential direction of the sensor magnet (110). The method of claim 1, The sensor magnet 110 is composed of a combination of magnet portions 111 divided into two or more in the circumferential direction. The magnet portion 111 has a magnetic force line from one end surface in the axial direction by an axial magnetization process. It is formed in the direction toward the opposite end surface via the circumferential portion with me, and the strength of the magnetic force detected in the circumference of each magnet portion 111 is the largest in the middle portion of the circumference length and gradually decreases in the circumferential direction. Rotor position detection device, characterized in that the adjacent magnet portion 111 is set in a direction opposite to each other. The method of claim 2, The magnet part 111, the rotor position detection device, characterized in that each made separately formed and then combined form. The method of claim 2, The linear Hall element (120) is a rotor position detection device, characterized in that it is arranged in a state maintaining the electrical phase difference of 90 degrees or 180 degrees at two or more of the circumference of the sensor magnet (100). Stator, which is the stator, Rotor that is a rotor, A device provided corresponding to the rotational axis of the rotor to detect the rotational position of the rotor, comprising a position detecting device according to any one of claims 1 to 4.

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