JP2021197895A - Three-phase brushless motor and rotational position detection method for three-phase brushless motor - Google Patents

Abstract

To detect the rotation position without using an expensive encoder in a three-phase brushless motor.SOLUTION: A three-phase brushless motor 100 includes a permanent magnet type rotor 300, a stator 200 that is configured such that an electrical phase difference between the three phases is 120 degrees and the number of slots is a multiple of 6, a first set of magnetic sensors, consisting of three magnetic sensors 410, 420, and 430, arranged at intervals of 120 degrees of electrical angle and detecting the magnetic field of the rotor, and a second set of magnetic sensors consisting of three magnetic sensors 411, 421, and 431 arranged so as to face each other in the radial direction with the three magnetic sensors in the first set and detecting the magnetic field of the rotor. The outputs of the two magnetic sensors arranged so as to face each other in the radial direction are combined, the three-phase output obtained by the combining is converted into two phases, and the rotation position of the rotor is detected from the converted output.SELECTED DRAWING: Figure 2

Description

The present invention relates to a three-phase brushless motor and a method for detecting a rotational position of a three-phase brushless motor.

As a conventional method for detecting the rotation position of a three-phase brushless motor and a three-phase brushless motor, there are, for example, Patent Document 1 and Patent Document 2.

Patent Document 1 relates to a magnetic pole position detection device and a drive device for a brushless DC motor, and in particular, a magnetic pole position detection device for detecting a magnetic pole position using a Hall element, and a sinusoidal PWM drive for the magnetic pole position detection device and the brushless DC motor. The present invention relates to a drive device for a brushless DC motor using a 180-degree energized inverter.

Patent Document 1 describes a magnetic pole position detection element unit that detects the magnetic pole position of a rotating body by three magnetic pole position detection elements using magnetic change, and a detection signal generation that generates a magnetic pole position detection signal based on the magnetic pole position. A magnetic pole position detection device having a unit and a control unit that controls the magnetic pole position detection based on the magnetic pole position detection signal is described. In this magnetic pole position detection device, the control unit has a conversion correction means for converting and correcting three magnetic pole position detection signals having a phase shift of 120 degrees each generated and output by the detection signal generation unit, and the three conversion corrections. The signal selection means for selecting a predetermined one magnetic pole position detection signal from the magnetic pole position detection signals, the relative magnetic pole position detecting means for detecting the relative magnetic pole position from the selected value of the magnetic pole position detection signal, and the selected one. It is characterized by having an absolute magnetic pole position detecting means for detecting a continuous absolute magnetic pole position from a section of the magnetic pole position detection signal and the relative magnetic pole position.

According to Patent Document 1, it is determined whether or not the motor is rotating at a low speed immediately after the motor is started, the offset correction amount and the amplitude correction amount are detected only at the low speed, and the offset correction and the amplitude correction are added to the detected digital detection values in other cases. I do. These detections and corrections are performed for each of the three phases. The amplitude and offset amount of the output signal waveform of each Hall element are detected using the maximum and minimum values of the digital detection value, and the correction amount of the digital detection value is determined and corrected, thereby causing a circuit component such as a Hall element. It is said that it is possible to detect the position of the magnetic pole with high accuracy by removing the influence of the variation of. Here, the permissible range is a value obtained in advance by an experiment and is stored in the ROM of the microcomputer.

Patent Document 2 describes an encoder that also serves as a rotor position detection sensor for drive control of a three-phase brushless motor. According to the same document, three magnetic sensors are arranged at intervals of 120 ° or 60 ° in the circumferential direction, and the magnetism is further placed at a position facing each of two of the three magnetic sensors at 180 °. The sensors are arranged, and the outputs of the magnetic sensors arranged at the positions facing each other by 180 ° are combined to detect the rotation position of the rotor. This document aims to suppress output voltage level fluctuations, and in order to cancel errors due to rotor eccentricity, magnetic flux unevenness, etc., two Hall elements are arranged face-to-face, output synthesis is performed, and level fluctuations are suppressed. Is described.

Japanese Unexamined Patent Publication No. 9-121584 Japanese Unexamined Patent Publication No. 2012-194086

In Patent Document 1, it is necessary to determine whether or not the vehicle is rotating at a low speed immediately after the motor is started, detect the offset correction amount and the amplitude correction amount only at the low speed, and further perform the offset amount and the amplitude error calculation. be. Further, it is necessary to store in the ROM of the microcomputer obtained in advance by experiment whether each operation is within the permissible range.

In Patent Document 2, a magnetic sensor is further arranged at a position facing 180 ° with respect to each of the two magnetic sensors, and the outputs of the magnetic sensors arranged at 180 ° facing each other are combined to synthesize a rotor. The rotation position of is detected. Then, the phase is converted from 120 ° to 90 °, and the rotor angle is converted as the relationship between the sine wave and the cosine wave. However, if the magnetic poles of the motor are magnetized with a trapezoidal wave, or if it is detected like a trapezoidal wave due to the arrangement of magnetic sensors even if it is magnetized with a sine wave, the sinusoidal wave or cosine wave In relation, the flat parts of two trapezoidal waves may partially overlap. In this overlap, the ratio of the sine wave and the cosine wave does not change, so that the rotor rotates, but the detection position does not change, making accurate position detection difficult.

In view of the prior art, it is an object of the present invention to efficiently detect a rotation position in a three-phase brushless motor by using a magnetic sensor that detects a magnetic field from a rotor magnet without using an expensive encoder. ..

In order to achieve the above object, the three-phase brushless motor according to the present invention has a permanent magnet type rotor in which N poles and S poles are alternately magnetized along the circumferential direction, and an electrical phase difference between the three phases. The first magnetic sensor is composed of a stator configured so that the number of slots is 120 degrees and the number of slots is a multiple of 6, and three magnetic sensors arranged at intervals of an electric angle of 120 degrees and detecting the magnetic field of the rotor. And the second set of magnetic sensors consisting of the three magnetic sensors in the first set and the three magnetic sensors arranged so as to face each other in the radial direction and detecting the magnetic field of the rotor. I have. The outputs of the two magnetic sensors arranged so as to face each other in the radial direction are combined, the three-phase output obtained by the synthesis is converted into two phases, and the rotation position of the rotor is calculated from the converted output. Detected.

According to the present invention, in a three-phase brushless motor, the rotation position can be efficiently detected by using a magnetic sensor that detects a magnetic field from a rotor magnet without using an expensive encoder.

It is sectional drawing of a three-phase brushless motor. It is explanatory drawing which shows the arrangement of the magnetic sensor in a three-phase brushless motor. It is a waveform diagram of the output signal of a magnetic sensor. It is a waveform diagram which shows the output waveform after converting the combined output waveform of U phase and V phase from 120 degree phase to 90 degree phase. It is a waveform diagram of U phase, V phase and W phase after synthesis. It is a waveform diagram which shows the output waveform after converting the waveform of FIG. 5 into two phases. It is an output waveform diagram of 90 degree phase by two magnetic sensors.

Hereinafter, the present invention will be described based on the illustrated embodiment. However, the present invention is not limited to the embodiments described below.

In the three-phase brushless motor, drive control is performed to rotate the rotor by changing the direction of the current flowing through the coil of the stator according to the rotation angle of the rotor. That is, the magnetic sensor for confirming the rotor position of the three-phase brushless motor detects the change in the magnetic flux due to the rotation of the rotor magnet, and changes the direction of the current flowing through the coil of the stator according to the detection result.

As the drive method of the three-phase brushless motor, there are a sine wave drive method driven by a sine wave synchronized with the rotation of the rotor and a square wave drive method driven by a square wave. Compared to the rectangular wave drive method, the sine wave drive method has better drive efficiency and less torque fluctuation, so that it has low vibration and low noise. In such drive control, a magnetic pole position sensor for generating a drive voltage in synchronization with the rotation of the rotor is used.

When detecting the magnetic poles of a three-phase brushless motor, an inexpensive alternating magnetic sensor (NS switch type) such as a Hall IC may be used as the magnetic sensor. The magnetic pole position is estimated by interpolation based on the elapsed time from the timing detected by these sensors. However, if the rotation speed of the motor is extremely low, or if the rotation of the motor is irregular or intermittent, interpolation may not be performed well.

When driving at extremely low speed, it is possible to detect the rotation position with high accuracy, and a high-speed resolver, encoder, or the like can be used. However, since the structure is complicated and a dedicated drive circuit is required, the drive system including the motor becomes large and expensive.

The inventor has invented a method for detecting the rotational position of a three-phase brushless motor and a three-phase brushless motor by using a magnetic sensor that is inexpensive and can detect magnetic poles in analog.

FIG. 1 is a cross-sectional view of a three-phase brushless motor 100 according to an embodiment. The three-phase brushless motor 100 includes a stator 200, a rotating shaft 350, and a rotor 300 assembled to the rotating shaft. A plurality of slots are formed in the stator 200, and windings are wound in the slots such as a U-phase winding portion 210. The rotor 300 has a rotor core 310 and a rotor magnet 320 provided on the peripheral surface of the rotor core. In this rotor magnet, the north pole and the south pole are alternately magnetized along the circumferential direction of the rotor. That is, the rotor 300 is a permanent magnet type rotor.

The three-phase brushless motor 100 further includes a magnetic sensor mounting substrate 450. The magnetic sensor mounting substrate 450 is arranged so as to face the rotor 300 in the direction of the rotation axis, and six magnetic sensors are mounted. As will be described later, these six magnetic sensors detect changes in the magnetic flux due to the rotation of the rotor 300, and detect the rotational position of the rotor 300. By changing the direction of the current flowing through the winding of the stator 200 according to the detection result, the rotor 300 and the rotating shaft 350 rotate at a predetermined speed.

FIG. 2 shows a three-phase brushless motor 100 in the direction of the rotation axis.

The stator 200 includes a total of 12 slots from the first slot S1 to the twelfth slot S12. The first slot S1 to the twelfth slot S12 are sequentially provided at equal intervals in the circumferential direction.

The U-phase first winding portion 210 includes a first winding portion 210a provided in the first slot S1 and a second winding portion 210b provided in the second slot S2. The winding direction (winding direction) of the first winding portion 210a and the second winding portion 210b is opposite to each other.
The V-phase first winding portion 220 includes a first winding portion 220a provided in the fourth slot S4 and a second winding portion 220b provided in the third slot S3. The winding directions of the first winding portion 220a and the second winding portion 220b are opposite to each other.
The W-phase first winding portion 230 includes a first winding portion 230a provided in the fifth slot S5 and a second winding portion 230b provided in the sixth slot S6. The winding directions of the first winding portion 230a and the second winding portion 230b are opposite to each other.

Similarly, in the seventh slot S7 to the twelfth slot S12, winding portions of each phase are provided.
That is, the U-phase second winding portion includes a first winding portion provided in the eighth slot S8 and a second winding portion provided in the seventh slot S7. The winding directions of both windings are opposite.
The V-phase second winding portion includes a first winding portion provided in the ninth slot S9 and a second winding portion provided in the tenth slot S10. The winding directions of both windings are opposite.
The W-phase second winding portion includes a first winding portion provided in the twelfth slot S12 and a second winding portion provided in the eleventh slot S11. The winding directions of both windings are opposite.

The rotor magnet 320 of the rotor 300 has 10 poles, and the north pole and the south pole are alternately magnetized along the circumferential direction. That is, the rotor 300 is a 10-pole permanent magnet type rotor.

The magnetic sensor mounting substrate 450 mounts a first set of magnetic sensors including magnetic sensors 410, 420 and 430, and a second set of magnetic sensors including magnetic sensors 411, 421 and 431. All six magnetic sensors in total are for detecting the rotational position of the rotor 300.

In the first set, the magnetic sensors 410, 420, and 430 are arranged so that their electrical angles are offset by 120 degrees. Specifically, the magnetic sensor 410 has a first winding portion 210a (first slot S1) and a second winding portion 210b (second slot S2) of the U-phase first winding portion 210 in the direction of the rotation axis. ) Is placed between. The magnetic sensor 420 is arranged between the first winding portion (9th slot S9) and the second winding portion (10th slot S10) of the V-phase second winding portion in the direction of the rotation axis. There is. The magnetic sensor 430 is located between the first winding portion 230a (fifth slot S5) of the W phase first winding portion 230 and the second winding portion 230b (sixth slot S6) in the direction of the rotation axis. Have been placed.

The magnetic sensors 410, 420, and 430 are all Hall elements that can detect magnetic poles in analog, or linear Hall ICs that have an amplification function in the Hall elements.

By arranging the magnetic sensors 410, 420, and 430 between two adjacent slots constituting the U phase, V phase, and W phase in the direction of rotation axis, respectively, the magnetism of the excitation of each phase winding is performed. The influence on the detection of the sensor can be suppressed.

Further, the magnetic sensors 411, 421 and 431 are arranged at positions facing the magnetic sensors 410, 420 and 430 in the radial direction, respectively. That is, the magnetic sensor 411 is arranged between the 7th slot S7 and the 8th slot S8, the magnetic sensor 421 is arranged between the 3rd slot S3 and the 4th slot S4, and the magnetic sensor 431 is the 11th slot S11. It is arranged between the twelfth slot S12 and the twelfth slot S12.

Similarly, the magnetic sensors 411, 421 and 431 are Hall elements capable of detecting magnetic poles in analog, or linear Hall ICs having an amplification function in the Hall elements.

The magnetic sensors 411, 421, and 431 are also placed between two adjacent slots constituting the U phase, V phase, and W phase in the direction of rotation axis, so that the magnetism of the excitation of each phase winding can be achieved. The influence on the detection of the sensor can be suppressed.

Next, the waveform of the detection signal of the magnetic sensor will be described. First, the magnetic sensor 410 and the magnetic sensor 411 arranged so as to face the magnetic sensor 410 in the radial direction will be described.

Looking at the output waveform A of the magnetic sensor 410 shown in FIG. 3, it can be seen that the amplitude is greatly deviated in one rotation (360 °). It is presumed that this is due to mechanical error due to eccentricity of the rotor.

Since the rotor 300 is a 10-pole permanent magnet type rotor in which N poles and S poles are alternately magnetized as described above, an output waveform of 5 cycles can be obtained in one rotation (360 °).

Similarly, the output waveform −A of the magnetic sensor 411, which is also shown in FIG. 3, has a phase opposite to that of the output waveform A of the magnetic sensor 410, and the amplitude is greatly deviated in one rotation (360 °) like the output waveform A. You can see that there is. Further, the output waveform −A has an opposite magnitude of the amplitude deviation as compared with the output waveform A of the magnetic sensor 410. For example, at the rotation position where the amplitude deviation of the output waveform A of the magnetic sensor 410 is large, the amplitude deviation of the output waveform A of the magnetic sensor 411 is small. Further, at the rotation position where the amplitude deviation of the output waveform A of the magnetic sensor 410 is small, the amplitude deviation of the output waveform A of the magnetic sensor 411 is large.

Therefore, as shown in the following equation, the output waveform A of the magnetic sensor 410 and the output waveform −A of the magnetic sensor 411 are calculated by taking a difference and dividing by 2, so that a mechanical error due to eccentricity of the rotor or the like is executed. Can be obtained, and the output waveform of the opposite cancellation shown in FIG. 3 can be obtained.
(A-(-A)) / 2 = average A (1)

Similarly, the output waveform B of the magnetic sensor 420 and the output waveform −B of the magnetic sensor 421 arranged so as to face the magnetic sensor 420 in the radial direction are also subjected to the following calculation to perform the eccentricity of the rotor and the like. It is possible to obtain an output waveform in which the mechanical error due to the above is canceled.
(B-(-B)) / 2 = average B (2)
This output waveform is 120 degrees out of phase with the combined output waveform of the magnetic sensors 410 and 411.

In principle, these two output waveforms can be converted from three phases having a 120 degree phase to two phases having a 90 degree phase, and the rotation position of the rotor 300 can be detected.

However, the rotor magnet 320 may be magnetized so that the detection signal of the magnetic sensor becomes a trapezoidal wave. Alternatively, even if the rotor magnet 320 is magnetized so that the detection signal of the magnetic sensor becomes a sine wave, the detection signal may become a trapezoidal wave depending on the arrangement of the magnetic sensor and the like.

As described above, the mechanical error is canceled from the output waveform obtained by synthesizing the waveforms of the magnetic sensors 410 and 411 and the output waveform obtained by synthesizing the waveforms of the magnetic sensors 420 and 421, and the phase is 120 ° to 90 °. FIG. 4 shows an output waveform converted into two phases, which are the phases. Reference numerals A1 and B1 indicate waveforms obtained by converting the 120 ° phase of the waveform obtained by combining the signal outputs A and −A and the waveform obtained by combining the signal outputs B and −B into 90 ° phase. As shown by reference numeral Z1, in the two-phase (relationship between sine wave and cosine wave), the flat portions of the trapezoidal wave partially overlap each other. Since the ratio of each phase does not change while the flat portions partially overlap, it is difficult to perform accurate position detection because the detection position does not change although the rotor is rotating.

Therefore, by further executing the following calculation for the output waveform C of the magnetic sensor 430 and the output waveform −C of the magnetic sensor 431, an output waveform in which the mechanical error due to the eccentricity of the rotor or the like is canceled is obtained. be able to.
(C-(-C)) / 2 = average C (3)
The phase of this output waveform is 120 degrees out of phase between the output waveform synthesized by the magnetic sensor 410 and the magnetic sensor 411 and the output waveform synthesized by the magnetic sensor 420 and the magnetic sensor 421.

FIG. 5 shows a three-phase output waveform in which mechanical errors due to eccentricity of the rotor are canceled. As for this output waveform, the output waveform of the magnetic sensor is detected like a trapezoidal wave instead of a sine wave due to the influence of the magnetic pole of the rotor magnet 320 and the arrangement of the magnetic sensor.

ただし、Ｈ_Ａ、Ｈ_Ｂ、Ｈ_Ｃはそれぞれ３相各出力波形値である。また、Ｈ_α、Ｈ_βはそれぞれ２相の出力波形値である。 By converting the three-phase output waveform of FIG. 5 from the three-phase to the two-phase shown by the following equation, the output waveforms of a sine wave and a chord wave with a phase difference of 90 degrees as shown in FIG. 6 can be obtained. be able to.

However, _HA , H _B , and H _C are output waveform values for each of the three phases. Further, H _α and H _β are output waveform values of two phases, respectively.

Even if it is a three-phase output waveform with a trapezoidal wave shape with a 120 ° phase difference, by converting from three-phase to two-phase, as shown in FIG. 6, a sine wave and a cosine wave with a 90 ° phase difference can be obtained. The output waveform is obtained. The rotation position of the rotor 300 can be detected from this output waveform.

Based on the above, in the three-phase brushless motor 100 shown in FIGS. 1 and 2, the rotation position is detected by the following three steps.
[First step]
The outputs of two magnetic sensors arranged so as to face each other in the radial direction are combined. That is, the outputs of the magnetic sensors 410 and 411 are combined as shown in the equation (1), the outputs of the magnetic sensors 420 and 421 are combined as shown in the equation (2), and the outputs of the magnetic sensors 430 and 431 are combined as shown in the equation (3). It is synthesized.
[Second step]
As shown in equation (4), the output of the three phases obtained in the first step is converted into two phases.
[Third step]
The rotation position of the rotor 300 is detected from the output after conversion to two phases.

In the above embodiment, the mechanical error of the rotating body is canceled by arranging the magnetic sensors mechanically facing each other by 180 degrees. Further, as a countermeasure against trapezoidal waves by the rotor magnet, a three-phase signal shifted by 120 degrees is detected instead of a two-phase signal shifted by 90 degrees, and the signal is converted into a two-phase signal again. Further, by arranging the magnetic sensor between two adjacent slots constituting each phase, the influence of the magnetic flux from the winding can be suppressed.

This makes it possible to know the rotation position of the rotor more accurately. Speed stability at low speeds is improved, and positioning accuracy is also improved. Even at extremely low speed drive, a sine wave and a chord wave with a phase difference of 90 degrees can be obtained, and the rotation position can be detected with high accuracy. Therefore, the drive control for rotating the rotor 300 can be performed by changing the direction of the current flowing through the winding of the stator 200 according to the rotation angle of the rotor 300. The three-phase brushless motor can be stably driven even at extremely low speeds.

According to the above embodiments, the effects listed below can be obtained.
-It is possible to cancel mechanical errors due to the eccentricity of the rotor and the mounting position of the magnetic sensor.
-Even if the output waveform of the magnetic sensor is trapezoidal, accurate position detection is possible.
-It is possible to detect the rotation position inexpensively and with high accuracy with a simple configuration without significantly changing the current 3-phase brushless motor structure.
・ Stable driving is possible even when driving at extremely low speeds.
-It can be kept at low cost while having the same accuracy as encoders and resolvers.

Ultra-low speed operation and positioning operation are possible by using a magnetic sensor that detects the magnetic field from the rotor magnet without using an expensive encoder.

FIG. 7 shows a 90-degree phase output waveform by two magnetic sensors as a comparative example. Reference numeral A2 indicates an output waveform of one magnetic sensor when two magnetic sensors are arranged at a position of 90 °, and reference numeral B2 indicates an output waveform of the other magnetic sensor. The figure shows a case where rotor angle conversion is performed as a relationship between a sine wave and a cosine wave from a magnetic sensor in a three-phase brushless motor in which the number of slots of the three-phase stator is a multiple of six. As shown by arrows Y1 and Y2, an amplitude error occurs due to the influence of mechanical error factors such as eccentricity. Further, as shown by reference numeral Z2, when the flat portions of the two trapezoidal waves A and B partially overlap each other, accurate position detection becomes difficult.

According to the above embodiment, the amplitude error (FIG. 7) and the offset can be dealt with, and even if the output waveform of the magnetic sensor is trapezoidal wavy, the position can be accurately detected. Although not shown, the offset means that the entire waveform is deviated from the 0 point in the vertical direction.

It should be noted that the calculation unit in the three-phase brushless motor 100 can perform conversion from three-phase to two-phase (equation (4)). Alternatively, a three-phase signal (formulas (1) to (3)) in which the mechanical error is canceled by two magnetic sensors facing each other in the radial direction is transmitted from the three-phase brushless motor 100 to the outside of the three-phase brushless motor 100. It may be output to a drive device or the like, and conversion from three phases to two phases (equation (4)) may be performed in the external drive device or the like.

Further, the output signals of the six magnetic sensors can be output from the three-phase brushless motor 100 to an external drive device or the like of the three-phase brushless motor 100. Then, in the external drive device or the like, after generating a three-phase signal in which the mechanical error is canceled by two magnetic sensors facing each other in the radial direction (formulas (1) to (3)), the three phases to 2 are generated. Conversion to phase (Equation (4)) can be performed.

[Other Examples]
Subsequently, another embodiment will be shown.
The 10-pole rotor 300 may be replaced with an 8-pole permanent magnet type rotor in which the N pole and the S pole are alternately magnetized in the circumferential direction. In this case, the magnetic sensors 410, 420, and 430 for detecting the rotation position are arranged at intervals of 60 degrees in the circumferential direction, and the magnetic sensors 411, 421, and 431 are arranged so as to face the magnetic sensors 410, 420, and 430 in the radial direction, respectively. Can be placed.

Further, in the above-mentioned 8-pole permanent magnet type rotor, the magnetic sensor may not be affected by the excitation of the U phase, the V phase, and the W phase. In this case, the magnetic sensors 410, 420, and 430 for detecting the rotation position are arranged at intervals of 30 degrees in the circumferential direction, and the magnetic sensors 411, 421 and 421 and 421 are arranged so as to face the magnetic sensors 410, 420, and 430 in the radial direction, respectively. 431 can be placed.

The three magnetic sensors 410, 420 and 430 in the first set of magnetic sensors may be arranged at intervals of 120 ° of electrical angle. The mechanical angle of the electric angle of 120 ° is determined in relation to the number of poles of the rotor. In the case of 10 poles, the mechanical angle is a multiple of 24 ° (however, since it is necessary to arrange three at 360 °, it is 120 ° or less). For 8 poles, the mechanical angle is a multiple of 30 °.

If the number of slots in the stator is a multiple of 12, the magnetic sensors 410, 420, and 430 are placed between two slots adjacent to each other in the circumferential direction constituting the U phase, V phase, and W phase in the direction of rotation axis, respectively. By arranging in, the influence of excitation can be eliminated. On the other hand, if the magnetic sensor is not likely to be affected by the excitation of the U phase, the V phase, and the W phase, the number of slots of the stator may be a multiple of 6. Furthermore, any phase winding of the stator does not necessarily have to be wound in a pair of slots adjacent in the circumferential direction.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and modifications can be made based on the technical idea of the present invention.

100 3-phase brushless motor 200 Stator 210 U-phase 1st winding part 220 V-phase 1st winding part 230 W-phase 1st winding part 300 Rotor 310 Rotor core 320 Rotor magnet 350 Rotating shaft 410, 420, 430, 411,421 , 431 Magnetic sensor 450 Magnetic sensor mounting board

Claims (8)

A permanent magnet type rotor in which the north and south poles are alternately magnetized along the circumferential direction,
A stator configured so that the electrical phase difference between the three phases is 120 degrees and the number of slots is a multiple of 6.
A first set of magnetic sensors, which are arranged at intervals of 120 degrees of electrical angle and consist of three magnetic sensors for detecting the magnetic field of the rotor,
It includes the three magnetic sensors in the first set and a second set of magnetic sensors each arranged so as to face each other in the radial direction and consisting of three magnetic sensors for detecting the magnetic field of the rotor.
The outputs of two magnetic sensors arranged so as to face each other in the radial direction are combined.
The output of the three phases obtained by the above synthesis is converted into two phases.
The rotation position of the rotor is detected from the output after the conversion.
3-phase brushless motor. The three-phase brushless motor according to claim 1, wherein any phase winding of the stator is wound in two slots adjacent to each other in the circumferential direction. The number of slots in the stator is a multiple of twelve.
Any phase winding of the stator is wound in two slots adjacent in the circumferential direction.
A magnetic sensor is arranged between the two slots in the direction of rotation of the three-phase brushless motor.
The three-phase brushless motor according to claim 1. The three-phase brushless motor according to claim 3, wherein the winding directions are opposite in the two slots. The three-phase brushless motor according to any one of claims 1 to 4, wherein the magnetic sensor is a Hall element or a linear Hall IC that outputs an analog signal. A permanent magnet type rotor in which the north and south poles are alternately magnetized along the circumferential direction,
A stator configured so that the electrical phase difference between the three phases is 120 degrees and the number of slots is a multiple of 6.
A first set of magnetic sensors, which are arranged at predetermined intervals in the circumferential direction and consist of three magnetic sensors for detecting the magnetic field of the rotor,
A three-phase having three magnetic sensors in the first set and a second set of magnetic sensors composed of three magnetic sensors arranged so as to face each other in the radial direction and detecting the magnetic field of the rotor. It is a method of detecting the rotation position of a brushless motor.
A synthesis step that synthesizes the outputs of two magnetic sensors arranged so as to face each other in the radial direction, and a synthesis step.
A conversion step for converting the three-phase output obtained by the synthesis step into two-phase,
A method for detecting a rotational position of a three-phase brushless motor, which comprises a detection step of detecting the rotational position of the rotor from the output obtained by the conversion step. The method for detecting a rotational position of a three-phase brushless motor according to claim 6, wherein the number of slots of the stator is a multiple of 12. Control of a three-phase brushless motor including a step of controlling the current of the winding of the stator by using the rotation position of the rotor detected by the rotation position detection method of the three-phase brushless motor according to claim 6 or 7. Method.

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