JP5266746B2 - Brushless motor, device, and robot - Google Patents

Abstract

The invention provides a brushless motor for rotating driven parts under the condition that a certer axis is not rotated. The brushless motor includes a stator (10) having a electromagnetic coil (12) and a position sensor (40); an axis (64) fixed to the stator (10); and a rotor (30) having a permanent magnet (32). The rotor (30) rotates around the axis (64). The rotor (30) is linked to a driven member (70, 71) that is driven by the brushless motor.

Description

  The present invention relates to a brushless motor using a permanent magnet and an electromagnetic coil.

  As a brushless motor using a permanent magnet and an electromagnetic coil, for example, a brushless motor described in Patent Document 1 below is known.

JP 2001-298882 A

  In the conventional electric motor, the rotor rotates in the stator, and the rotation of the rotor is transmitted to the rotation shaft by fixing the rotor and the rotation shaft. Then, by using a transmission means such as a gear, or by directly connecting a wheel or the like to the rotation shaft, the rotational motion of the rotation shaft is transmitted to a driven member such as a wheel. However, in this configuration, there is a problem that a delay occurs until the rotational motion of the rotor is transmitted to a driven member such as a wheel due to the occurrence of twisting of the rotating shaft, etc. There was a problem that a large torsional strength was required for the rotating shaft. Such a problem is not limited to the motor, but is common to generators.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique capable of rotating a driven member without rotating the central axis of the motor.

In order to solve at least a part of the above-described problems, the present invention can take the following forms.
[Form]
A brushless motor for driving a driven member,
A stator having an A phase coil group, a B phase coil group, an electromagnetic coil, and a position sensor;
A shaft portion fixed to the stator;
A rotor having a permanent magnet, rotating around the shaft, and coupled to the driven member;
A drive circuit unit that is provided in the stator and generates a drive signal for driving the brushless motor;
Wiring provided in at least a part of the inside of the shaft portion and connected to the drive circuit unit;
With
The rotor has a first rotor and a second rotor connected to the first rotor and fixed in a relative position with respect to the first rotor;
The first rotor and the second rotor sandwich the stator,
The first rotor has a first permanent magnet group and is disposed on one side of the stator,
The second rotor has a second permanent magnet group and is disposed on the other side of the stator,
The stator has a first surface and a second surface that is a surface opposite to the first surface;
The A-phase coil group is disposed on the first surface of the stator, but is not disposed on the second surface,
The B phase coil group is disposed on the second surface of the stator, but is not disposed on the first surface,
The A phase coil group and the B phase coil group are arranged with an electrical angle shifted by π / 2,
The A phase and B phase coil groups do not have a magnetic core,
The number of permanent magnets included in the first permanent magnet group is equal to the number of electromagnetic coils included in the A-phase coil group,
The number of permanent magnets included in the second permanent magnet group is equal to the number of electromagnetic coils included in the B-phase coil group,
The number of permanent magnets included in the first permanent magnet group is equal to the number of permanent magnets included in the second permanent magnet group;
The permanent magnets included in the first permanent magnet group are each arranged at a constant magnetic pole pitch, and the adjacent permanent magnets are magnetized in opposite directions,
The permanent magnets included in the second permanent magnet group are each arranged at a constant magnetic pole pitch, and the adjacent permanent magnets are magnetized in opposite directions,
The permanent magnets included in the first and second permanent magnet groups are arranged such that the magnetic poles directed to the stator have different polarities,
The pitch of the permanent magnets included in the first and second permanent magnet groups is equal to the pitch of the coils belonging to the A phase and B phase coil groups,
The direction of the magnetic flux of the first and second permanent magnet groups is perpendicular to the stator;
An AC drive signal is supplied to the A phase and B phase coil groups as the drive signal.
Brushless motor.

[Form 1]
A brushless motor,
A stator having an electromagnetic coil and a position sensor;
A shaft portion fixed to the stator;
A rotor having a permanent magnet and rotating around the shaft portion;
With
The rotor is a brushless motor connected to a driven member driven by the brushless motor.

  According to the brushless motor of aspect 1, since the shaft portion is fixed to the stator, the rotor rotates around the shaft portion, and the driven member is connected to the rotor, the driven member is not rotated without rotating the central shaft of the motor. The drive member can be rotated.

[Form 2]
A brushless motor according to the first aspect,
A brushless motor, wherein wiring for driving the brushless motor is provided inside the shaft portion.

  According to the brushless motor of aspect 2, since the wiring is provided inside the shaft portion, the space of the wiring portion can be saved.

[Form 3]
The brushless motor according to the first or second aspect,
The rotor has a shape that wraps the stator inside,
The permanent magnet is a brushless motor provided in an inner portion of the rotor.

  According to the brushless motor of aspect 3, it is possible to realize a sealed structure that is resistant to dirt and the like from the outside.

[Form 4]
The brushless motor according to any one of Forms 1 to 3,
The position sensor is a brushless motor including a magnetic sensor that outputs an output signal indicating an analog change according to a relative position between the stator and the rotor.

  According to the brushless motor of aspect 4, it is possible to efficiently drive the brushless motor by utilizing the analog change of the magnetic sensor.

[Form 5]
A brushless motor according to mode 4,
The stator further comprises:
A brushless comprising a control circuit including a PWM control circuit that generates a drive signal that simulates an analog change in the output signal of the magnetic sensor by executing PWM control using an analog change in the output signal of the magnetic sensor. motor.

  According to the brushless motor of aspect 5, since the brushless motor can be driven by a drive signal having a shape close to the counter electromotive force waveform of the coil, the efficiency can be improved.

[Form 6]
A brushless motor according to the fifth aspect,
The control circuit further includes:
A brushless motor comprising a regenerative circuit for regenerating power from the electromagnetic coil.

  According to the brushless motor of aspect 6, it is possible to generate power using the regenerative circuit.

[Form 7]
A brushless motor according to the sixth aspect,
A brushless motor, wherein wiring for recovering regenerative power from the regenerative circuit is provided inside the shaft portion.

  According to the brushless motor of aspect 7, since the wiring is provided inside the shaft portion, space saving of the wiring portion can be achieved.

[Form 8]
A brushless motor according to any one of forms 5 to 7,
A brushless motor in which at least a part of the electromagnetic coil, the position sensor, and the control circuit is covered with resin.

  According to the brushless motor of aspect 8, corrosion of the electromagnetic coil or the like can be suppressed.

  The present invention can be realized in various forms, for example, a brushless motor, a brushless generator, a control method (or drive method) thereof, an actuator using them, a power generator, a moving body, and the like. It can be realized in the form.

Next, embodiments of the present invention will be described in the following order.
A. Overview of motor configuration and operation of the first embodiment:
B. Configuration of drive circuit unit:
C. Modification of the motor configuration of the first embodiment:
D. Motor configuration of the second embodiment:
E. Motor configuration of the third embodiment:
F. Variations:

A. Overview of motor configuration and operation of the first embodiment:
1A to 1D are cross-sectional views illustrating the configuration of a motor body of a brushless motor as a first embodiment of the present invention. The motor body includes a shaft portion 64, a stator portion 10, and a rotor portion 30. The stator part 10 and the rotor part 30 have a substantially disk shape. The shaft portion 64 is attached to the suspension 1 of a moving body such as a vehicle by a shaft fixing portion 64a, and is fixed so that the shaft portion 64 itself does not rotate. The rotor unit 30 includes an upper rotor unit 30U and a lower rotor unit 30L. FIG. 1B is a horizontal sectional view of the upper rotor portion 30U. The upper rotor portion 30U includes an upper rotary casing portion 31U, a bearing portion 65U, and four substantially fan-shaped permanent magnets 32U, and can rotate around the shaft portion 64 via the bearing portion 65U. It is. The bearing portion 65U can be realized using, for example, a ball bearing. Since the lower rotor portion 30L has the same configuration as the upper rotor portion 30U, the illustration is omitted. The magnetization directions of the permanent magnets 32 </ b> U and 32 </ b> L are parallel to the shaft portion 64. A shaft end portion fixing member 64e is attached to the end portion of the shaft portion 64 (FIG. 1A), so that the bearing portion 65U does not come off by rotation. A wheel portion 70 is fixed to the upper rotating casing portion 31U by a fixing screw portion 50. A sealing cap 70c is attached to the central portion of the wheel portion 70 to prevent foreign matter and the like from entering the motor. A wheel portion 71 that functions as a wheel of the moving body is attached to the outer peripheral portion of the wheel portion 70.

  FIG. 1C is a horizontal sectional view of the stator portion 10. As shown in FIG. 1A, the stator unit 10 has a plurality of A-phase coils 12A, a plurality of B-phase coils 12B, and a support member 14 that supports these coils 12A and 12B. FIG. 1C shows the side of the A-phase coil 12A. In this example, four A-phase coils 12A are provided, each wound in a substantially fan shape. The same applies to the B-phase coil 12B. The stator unit 10 is further provided with a drive circuit unit 500. As shown in FIG. 1A, the central portion of the shaft portion 64 has a hollow structure, and is used to send a signal to the drive power line 278 for supplying power to each coil 12 and the drive circuit unit 500. It is preferable to pass the control line 279 and the like. In addition, when recovering regenerative power from each coil 12 (which will be described later), a receiving power line 280 (hereinafter also referred to as “regenerative power supply wiring 280”) may be passed through the hollowed out portion. preferable. This is because wiring space can be saved.

  When the motor is configured as described above, the rotor portion 30 rotates around the shaft portion 64 to rotate the wheel, and the shaft portion 64 is fixed and does not rotate (FIG. 1A). Therefore, no twisting force is applied to the shaft portion 64. For this reason, it is not necessary to increase the torsional strength of the shaft portion 64, and the motor can be reduced in weight. Since the shaft portion 64 is not twisted and there is no need to use a transmission means such as a gear, there is no transmission loss, and stable control and a high response speed can be realized. This is particularly effective in posture control or the like that requires a fast response speed of normal rotation and reverse rotation.

  During motor maintenance, the shaft fixing portion 64a can be used to separate the motor from the moving body such as the suspension 1 together with the shaft portion 64, so that the upper and lower rotor portions 30U and 30L can be easily disassembled. Therefore, overall maintainability of the wheel portion 71, the wheel portion 70, the shaft portion 64, the stator portion 10, the rotor portion 30 and the like is excellent. In addition, since it is easy to replace the stator unit 10 and the rotor unit 30 with a stator unit and a rotor unit having other characteristics, it is possible to easily change or improve the power characteristics of the moving body. Become. Furthermore, since the wheel part 70 and the wheel part 71 can be easily detached from the rotor part 30 by the fixing screw part 50, the wheel part 70 and the wheel part 71 can be maintained separately from the motor body. . In addition, since the heat generated in the rotor part 30 can be thermally conducted to the outside of the motor by using the upper rotary casing part 31U as a heat dissipation structure, the motor of this embodiment has an advantage that the heat dissipation effect is high.

  Furthermore, as shown in FIG. 1A, if the stator portion 10 is completely covered by the upper and lower rotary casing portions 31U and 31L, a sealed structure that is resistant to dirt from the outside can be easily realized. . Therefore, if this sealed structure is utilized, it can also be used as a wheel of an amphibious vehicle. Further, if this motor is used for a fan motor that is affected by dust or the like, dust or the like does not enter the motor, so that maintenance-free operation can be realized. The wheel portion 70 and the wheel portion 71 correspond to the “driven member” in the present invention.

  FIG. 1D is a conceptual diagram showing the relationship between the stator portion 10 and the upper and lower rotor portions 30U, 30L. However, the rotating casing part 31 and the bearing part 65 are omitted in the rotor part 30. On the support member 14 of the stator portion 10, a magnetic sensor 40A for A phase and a magnetic sensor 40B for B phase are provided. The magnetic sensors 40A and 40B are for detecting the positions of the rotor portions 30U and 30L (that is, the phase of the motor). Hereinafter, these sensors are also referred to as “A-phase sensor” and “B-phase sensor”. The A-phase sensor 40A is disposed at the center position between the two A-phase coils 12A. Similarly, the B-phase sensor 40B is also arranged at the center position between the two B-phase coils 12B. In this example, the B-phase sensor 40B is disposed on the upper surface of the support member 14 together with the A-phase coil 12B. Alternatively, the B-phase sensor 40B may be disposed on the lower surface of the support member 14. The same applies to the A-phase sensor 40A. As can be understood from FIG. 1C, in this embodiment, since the B-phase sensor 40B is arranged inside the A-phase coil 12A, there is an advantage that it is easy to secure a space for arranging the sensor 40B.

  As shown in FIG. 1D, the magnets 32U and 32L are arranged at a constant magnetic pole pitch Pm, and adjacent magnets are magnetized in opposite directions. The A-phase coil 12A is arranged at a constant pitch Pc, and adjacent coils are excited in opposite directions. The same applies to the B-phase coil 12B. In this embodiment, the magnetic pole pitch Pm is equal to the coil pitch Pc and corresponds to π in electrical angle. The electrical angle 2π is associated with a mechanical angle or distance that moves when the phase of the drive signal changes by 2π. In this embodiment, when the phase of the drive signal changes by 2π, the rotor portions 30U and 30L move by twice the magnetic pole pitch Pm. Further, the A-phase coil 12A and the B-phase coil 12B are arranged at positions where the phases are shifted by π / 2.

  The magnet 32U of the upper rotor part 30U and the magnet 32L of the lower rotor part 30L are arranged such that the magnetic poles directed to the stator part 10 have different polarities (S pole and N pole). In other words, the magnet 32U of the upper rotor portion 30U and the magnet 32L of the lower rotor portion 30L are arranged so that opposite poles face each other. As a result, as shown at the right end of FIG. 1 (D), the magnetic field between these magnets 32U and 32L is represented by a substantially linear magnetic field line, and is closed between these magnets 32U and 32L. It will be a thing. It can be understood that such a closed magnetic field is stronger than an open magnetic field. As a result, the use efficiency of the magnetic field is increased, and the motor efficiency can be improved. In addition, it is preferable that the magnetic yokes 34U and 34L made from a ferromagnetic material are provided on the outer surfaces of the magnets 32U and 32L, respectively. The magnetic yokes 34U and 34L can further strengthen the magnetic field in the coil. However, the magnetic yokes 34U and 34L may be omitted.

  In addition, it is preferable to cover any or all of the coils 12A and 12B, the magnetic sensors 40A and 40B, and the drive circuit unit 500 with resin. This is because such corrosion can be suppressed. Further, if the resin covering the coils 12A, 12B, etc. is brought into contact with the shaft portion 64, the heat generated from the coils 12A, 12B, etc. is transmitted to the shaft portion 64 by the resin, and the shaft portion 64 is used as a heat sink. , 12B, etc. can be cooled.

  FIG. 2 is an explanatory diagram showing the relationship between the sensor output and the back electromotive force waveform of the coil. FIG. 2A is the same as FIG. FIG. 2 (B) shows an example of the waveform of the counter electromotive force generated in the A-phase coil 12A. FIGS. 2 (C) and 2 (D) show sensor outputs SSA of the A-phase sensor 40A and the B-phase sensor 40B. , SSB waveform examples are shown. These sensors 40A and 40B can generate sensor outputs SSA and SSB that are substantially similar to the back electromotive force of the coil during motor operation. The counter electromotive force of the coil 12A shown in FIG. 2B tends to increase with the number of rotations of the motor, but the waveform shape (sine wave) is kept substantially similar. As the sensors 40A and 40B, for example, a Hall IC using the Hall effect can be employed. In this example, the sensor output SSA and the back electromotive force Ec are both sine waves or waveforms close to a sine wave. As will be described later, the drive control circuit of the motor applies a voltage having a waveform substantially similar to the back electromotive force Ec to the coils 12A and 12B using the sensor outputs SSA and SSB.

  By the way, the electric motor functions as an energy conversion device that mutually converts mechanical energy and electrical energy. The back electromotive force of the coil is obtained by converting the mechanical energy of the electric motor into electrical energy. Therefore, when the electrical energy applied to the coil is converted into mechanical energy (that is, when the motor is driven), the motor is driven most efficiently by applying a voltage having a waveform similar to the counter electromotive force. Is possible. As described below, “a voltage having a waveform similar to that of the back electromotive force” means a voltage that generates a current in the opposite direction to the back electromotive force.

  FIG. 3A is a schematic diagram showing the relationship between the applied voltage of the coil and the back electromotive force. Here, the coil is simulated by an alternating back electromotive force Ec and a resistance Rc. In this circuit, a voltmeter V is connected in parallel with the AC applied voltage Ei and the coil. The counter electromotive force Ec is also referred to as “induced voltage Ec”, and the applied voltage Ei is also referred to as “excitation voltage Ei”. When an AC voltage Ei is applied to the coil to drive the motor, a back electromotive force Ec is generated in a direction in which a current opposite to the applied voltage Ei flows. When the switch SW is opened while the motor is rotating, the back electromotive force Ec can be measured by the voltmeter V. The polarity of the back electromotive force Ec measured with the switch SW opened is the same polarity as the applied voltage Ei measured with the switch SW closed. In the above description, the phrase “applying a voltage having a waveform similar to that of the back electromotive force” refers to a voltage having a waveform having a substantially similar shape having the same polarity as the back electromotive force Ec measured by the voltmeter V. It means to apply.

  FIG. 3B shows an outline of the driving method employed in this embodiment. Here, the motor is simulated by the A-phase coil 12A, the permanent magnet 32U, and the A-phase sensor 40A. When the rotor unit 30 having the permanent magnet 32U rotates, an AC voltage Es (also referred to as “sensor voltage Es”) is generated in the sensor 40A. The sensor voltage Es has a waveform shape similar to the induced voltage Ec of the coil 12A. Therefore, by generating a PWM signal simulating the sensor voltage Es and performing on / off control of the switch SW, it is possible to apply the excitation voltage Ei having a waveform similar to the induced voltage Ec to the coil 12A. The exciting current Ii at this time is given by Ii = (Ei−Ec) / Rc.

  As described above, when the motor is driven, the motor can be driven most efficiently by applying a voltage having a waveform similar to that of the counter electromotive force. Note that the energy conversion efficiency is relatively low near the middle point of the sinusoidal back electromotive force waveform (near voltage 0), and conversely, the energy conversion efficiency is relatively high near the peak of the back electromotive force waveform. it can. When the motor is driven by applying a voltage having a waveform similar to the counter electromotive force, a relatively high voltage is applied during a period of high energy conversion efficiency, so that the motor efficiency is improved. On the other hand, for example, when the motor is driven with a simple rectangular wave, a considerable voltage is applied even in the vicinity of the position where the back electromotive force is almost zero (middle point), so that the motor efficiency is lowered. In addition, when a voltage is applied in such a period with low energy conversion efficiency, vibration in a direction other than the rotation direction is caused by an eddy current, thereby causing a problem that noise is generated.

  As can be understood from the above description, when the motor is driven by applying a voltage having a waveform similar to that of the back electromotive force, the motor efficiency can be improved, and vibration and noise can be reduced. .

  FIGS. 4A to 4D are explanatory views showing the state of forward rotation of the brushless motor of this embodiment. FIG. 4A shows a state immediately before the phase is zero. The letters “N” and “S” written at the positions of the A-phase coil 12A and the B-phase coil 12B indicate the excitation directions of these coils 12A and 12B. When the coils 12A and 12B are excited, an attractive force and a repulsive force are generated between the coils 12A and 12B and the magnets 32U and 32L. As a result, the rotor portions 30U and 30L rotate in the normal rotation direction (right direction in the figure). At the timing when the phase becomes 0, the excitation direction of the A-phase coil 12A is reversed (see FIG. 2). FIG. 4B shows a state where the phase has advanced to just before π / 2. At the timing when the phase becomes π / 2, the excitation direction of the B-phase coil 12B is reversed. FIG. 4C shows a state where the phase has advanced to just before π. At the timing when the phase becomes π, the excitation direction of the A-phase coil 12A is reversed again. FIG. 4D shows a state in which the phase has advanced to just before 3π / 2. At the timing when the phase becomes 3π / 2, the excitation direction of the B-phase coil 12B is reversed again.

  As can be understood from FIGS. 2C and 2D, since the sensor outputs SSA and SSB become zero at the timing when the phase is an integral multiple of π / 2, the two-phase coils 12A and 12B Driving force is generated from only one of them. However, both of the two-phase coils 12A and 12B can simultaneously generate driving force in all other periods except for the timing when the phase is an integral multiple of π / 2. Therefore, a large torque can be generated using both of the two-phase coils 12A and 12B.

  As can be understood from FIG. 4A, the A-phase sensor 40A is disposed at a position where the polarity of the sensor output is switched at a position where the center of the A-phase coil 12A faces the center of the permanent magnet 32U. Similarly, the B-phase sensor 40B is disposed at a position where the polarity of the sensor output is switched at a position where the center of the B-phase coil 12B faces the center of the permanent magnet 32L. If the sensors 40A and 40B are arranged at such positions, it is possible to generate sensor outputs SSA and SSB (FIG. 2) having a shape substantially similar to the counter electromotive force of the coil from the sensors 40A and 40B.

  FIGS. 5A to 5D are explanatory views showing the reverse operation of the brushless motor of this embodiment. FIGS. 5A to 5D show states where the phases are immediately before 0, π / 2, π, and 3π / 2, respectively. This reverse operation can be realized, for example, by inverting the polarity (that is, positive / negative) of the drive voltage of the coils 12A and 12B from the drive voltage of the normal operation.

B. Configuration of drive circuit unit:
FIG. 6 is a block diagram illustrating an internal configuration of the drive circuit unit in the embodiment. The drive circuit unit 500 includes a CPU 110, a drive control unit 100, a regeneration control unit 200, a driver circuit 150, a rectifier circuit 250, and a power supply unit 300. The two control units 100 and 200 are connected to the CPU 110 via the bus 102. The drive control unit 100 and the driver circuit 150 are circuits that perform control when a driving force is generated in the electric motor. The regeneration control unit 200 and the rectifier circuit 250 are circuits that perform control when power is regenerated from the electric motor. The regeneration control unit 200 and the rectifier circuit 250 are collectively referred to as a “regeneration circuit”. The drive control unit 100 is also referred to as a “drive signal generation circuit”. The power supply unit 300 is a circuit for supplying various power supply voltages to other circuits in the drive circuit unit 500. In FIG. 6, for convenience of illustration, only the power supply wiring from the power supply unit 300 to the drive control unit 100 and the driver circuit 150 is illustrated, and the power supply wiring to the other circuits is omitted.

  FIG. 7 shows the configuration of phase A driver circuit 120A and phase B driver circuit 120B included in driver circuit 150 (FIG. 6). The A-phase driver circuit 120A is an H-type bridge circuit for supplying AC drive signals DRVA1 and DRVA2 to the A-phase coil 12A. A white circle attached to the terminal portion of the block indicating the drive signal is negative logic and indicates that the signal is inverted. In addition, arrows with symbols IA1 and IA2 indicate the directions of currents flowing by the A1 drive signal DRVA1 and the A2 drive signal DRVA2, respectively. The configuration of the B phase driver circuit 120B is the same as the configuration of the A phase driver circuit 120A. If the negative logic that inverts the signal is eliminated and the P channel MOS-FET on the H side is changed to the same N channel MOS-FET as that on the L side, driving with excellent frequency characteristics can be realized.

  FIG. 8 is an explanatory diagram showing the internal configuration and operation of the drive control unit 100 (FIG. 6). The drive control unit 100 includes a basic clock generation circuit 510, a 1 / N frequency divider 520, a PWM unit 530, a forward / reverse direction value register 540, a multiplier 550, an encoding unit 560, and an AD conversion unit. 570, a voltage command value register 580, and an excitation interval setting unit 590. The drive control unit 100 is a circuit that generates both an A-phase drive signal and a B-phase drive signal, and includes a basic clock generation circuit 510, a frequency divider 520, and a forward / reverse direction instruction value register 540. Are commonly used in the A phase and the B phase. The other components existing for the A phase and the B phase are depicted as only the A phase circuit configuration in FIG. 8A for convenience of illustration, but the A phase is also used for the B phase. The same components as those for the phase are provided in the drive control unit 100.

  The basic clock generation circuit 510 is a circuit that generates a clock signal PCL having a predetermined frequency, and is composed of, for example, a PLL circuit. The frequency divider 520 generates a clock signal SDC having a frequency 1 / N of the clock signal PCL. The value of N is set to a predetermined constant value. The value of N is set in the frequency divider 520 by the CPU 110 in advance. The PWM unit 530 is supplied from the clock signals PCL and SDC, the multiplication value Ma supplied from the multiplier 550, the forward / reverse direction indication value RI supplied from the forward / reverse direction indication value register 540, and the encoding unit 560. AC drive signals DRVA1 and DRVA2 (FIG. 7) are generated according to the positive / negative sign signal Pa and the excitation interval signal Ea supplied from the excitation interval setting unit 590. This operation will be described later.

  In the forward / reverse direction value register 540, a value RI indicating the rotation direction of the motor is set by the CPU 110. In the present embodiment, the motor rotates forward when the forward / reverse direction instruction value RI is at L level, and reverses when it is at H level. Other signals Ma, Pa, and Ea supplied to the PWM unit 530 are determined as follows.

  The output SSA of the magnetic sensor 40A is supplied to the AD converter 570. The range of the sensor output SSA is, for example, from GND (ground potential) to VDD (power supply voltage), and the middle point (= VDD / 2) is the middle point of the output waveform (point passing through the origin of the sine wave). It is. The AD conversion unit 570 performs AD conversion on the sensor output SSA to generate a digital value of the sensor output. The output range of the AD converter 570 is, for example, FFh to 0h ("h" at the end indicates a hexadecimal number), and the median value 80h corresponds to the middle point of the sensor waveform.

  The encoding unit 560 converts the range of the sensor output value after AD conversion, and sets the middle value of the sensor output value to 0. As a result, the sensor output value Xa generated by the encoding unit 560 takes a value in a predetermined range on the positive side (for example, +127 to 0) and a predetermined range on the negative side (for example, 0 to -127). However, what is supplied from the encoding unit 560 to the multiplier 550 is the absolute value of the sensor output value Xa, and the sign of the sensor output value Xa is supplied to the PWM unit 530 as the sign signal Pa.

  Voltage command value register 580 stores voltage command value Ya set by CPU 110. This voltage command value Ya functions as a value for setting the applied voltage of the motor together with an excitation interval signal Ea described later, and takes a value of 0 to 1.0, for example. If the excitation interval signal Ea is set so that the entire excitation interval is set without providing a non-excitation interval, Ya = 0 means that the applied voltage is zero, and Ya = 1.0 is This means that the applied voltage is the maximum value. Multiplier 550 multiplies sensor output value Xa output from encoding unit 560 and voltage command value Ya to produce an integer, and supplies the multiplied value Ma to PWM unit 530.

  8B to 8E show the operation of the PWM unit 530 when the multiplication value Ma takes various values. Here, it is assumed that the entire period is an excitation interval and there is no non-excitation interval. The PWM unit 530 is a circuit that generates one pulse with a duty of Ma / N during one cycle of the clock signal SDC. That is, as shown in FIGS. 8B to 8E, the duty of the pulses of the drive signals DRVA1 and DRVA2 increases as the multiplication value Ma increases. The first drive signal DRVA1 is a signal that generates a pulse only when the sensor output SSA is positive, and the second drive signal DRVA2 is a signal that generates a pulse only when the sensor output SSA is negative. However, in FIGS. 8B to 8E, these are described together. For convenience, the second drive signal DRVA2 is drawn as a negative pulse.

  FIGS. 9A to 9C are explanatory diagrams illustrating a correspondence relationship between the waveform of the sensor output and the waveform of the drive signal generated by the PWM unit 530. In the figure, “Hiz” means a high impedance state in which the electromagnetic coil is in an unexcited state. As described with reference to FIG. 8, the drive signals DRVA1 and DRVA2 are generated by PWM control using the analog waveform of the sensor output SSA as it is. Therefore, using these drive signals DRVA1 and DRVA2, it is possible to supply an effective voltage indicating a level change corresponding to the change of the sensor output SSA to each coil.

  Further, the PWM unit 530 outputs a drive signal only in the excitation interval indicated by the excitation interval signal Ea supplied from the excitation interval setting unit 590, and does not output a drive signal in intervals other than the excitation interval (non-excitation interval). It is configured. FIG. 9C shows drive signal waveforms when the excitation interval EP and the non-excitation interval NEP are set by the excitation interval signal Ea. In the excitation interval EP, the drive signal pulse of FIG. 9B is generated as it is, and no drive signal pulse is generated in the non-excitation interval NEP. Thus, if the excitation interval EP and the non-excitation interval NEP are set, no voltage is applied to the coil in the vicinity of the middle point of the back electromotive force waveform (that is, in the vicinity of the middle point of the sensor output). It is possible to further improve the efficiency. The excitation interval EP is preferably set to a symmetrical interval centered on the peak of the back electromotive force waveform, and the non-excitation interval NEP is centered on the middle point (center point) of the back electromotive force waveform. It is preferable to set to a symmetrical section.

  As described above, when the voltage command value Ya is set to a value less than 1, the multiplication value Ma becomes smaller in proportion to the voltage command value Ya. Therefore, the effective applied voltage can be adjusted also by the voltage command value Ya.

  As can be understood from the above description, in the motor of this embodiment, it is possible to adjust the applied voltage using both the voltage command value Ya and the excitation interval signal Ea. The relationship between the desired applied voltage, the voltage command value Ya, and the excitation interval signal Ea is preferably stored in advance as a table in a memory in the drive circuit unit 500 (FIG. 6). In this way, when the drive circuit unit 500 receives the target value of the desired applied voltage from the outside, the CPU 110 sends the voltage command value Ya and the excitation interval signal Ea to the drive control unit 100 according to the target value. It is possible to set. Note that it is not necessary to use both the voltage command value Ya and the excitation interval signal Ea to adjust the applied voltage, and only one of them may be used.

  FIG. 10 is a block diagram showing an example of the internal configuration of the PWM unit 530 (FIG. 8). The PWM unit 530 includes a counter 531, an EXOR circuit 533, and a drive waveform forming unit 535. These operate as follows.

  FIG. 11 is a timing chart showing the operation of the PWM unit 530 during normal rotation of the motor. In this figure, two clock signals PCL and SDC, forward / reverse direction instruction value RI, excitation interval signal Ea, multiplication value Ma, positive / negative sign signal Pa, count value CM1 in counter 531 and counter 531 The output S1, the output S2 of the EXOR circuit 533, and the output signals DRVA1 and DRVA2 of the drive waveform forming unit 535 are shown. The counter 531 repeats the operation of down-counting the count value CM1 to 0 in synchronization with the clock signal PCL every period of the clock signal SDC. The initial value of the count value CM1 is set to the multiplication value Ma. In FIG. 11, a negative value is also drawn as the multiplication value Ma for convenience of illustration, but the counter 531 uses the absolute value | Ma |. The output S1 of the counter 531 is set to H level when the count value CM1 is not 0, and falls to L level when the count value CM1 becomes 0.

  The EXOR circuit 533 outputs a signal S2 indicating an exclusive OR of the positive / negative sign signal Pa and the forward / reverse direction instruction value RI. When the motor rotates normally, the forward / reverse direction instruction value RI is at the L level. Therefore, the output S2 of the EXOR circuit 533 is the same signal as the positive / negative sign signal Pa. The drive waveform forming unit 535 generates drive signals DRVA1 and DRVA2 from the output S1 of the counter 531 and the output S2 of the EXOR circuit 533. That is, out of the output S1 of the counter 531, the signal during the period in which the output S2 of the EXOR circuit 533 is at the L level is output as the first drive signal DRVA1, and the signal during the period in which the output S2 is at the H level Output as. In the vicinity of the right end of FIG. 11, the excitation interval signal Ea falls to the L level, thereby setting the non-excitation interval NEP. Accordingly, in this non-excitation interval NEP, none of the drive signals DRVA1, DRVA2 is output and the high impedance state is maintained.

  FIG. 12 is a timing chart showing the operation of the PWM unit 530 during motor reverse rotation. During reverse rotation of the motor, the forward / reverse direction instruction value RI is set to H level. As a result, the two drive signals DRVA1 and DRVA2 are interchanged from FIG. 11, and as a result, it can be understood that the motor reverses.

  FIG. 13 is an explanatory diagram showing the internal configuration and operation of the excitation interval setting unit 590. The excitation interval setting unit 590 includes an electronic variable resistor 592, voltage comparators 594, 596, and an OR circuit 598. The resistance value Rv of the electronic variable resistor 592 is set by the CPU 110. Voltages V1 and V2 across the electronic variable resistor 592 are applied to one input terminal of a voltage comparator 594,596. A sensor output SSA is supplied to the other input terminal of the voltage comparators 594 and 596. Output signals Sp and Sn of the voltage comparators 594 and 596 are input to the OR circuit 598. The output of the OR circuit 598 is an excitation interval signal Ea for distinguishing between excitation intervals and non-excitation intervals.

  FIG. 13B shows the operation of the excitation interval setting unit 590. Both-end voltages V1 and V2 of the electronic variable resistor 592 are changed by adjusting the resistance value Rv. Specifically, both-end voltages V1 and V2 are set to values having the same difference from the median value (= VDD / 2) of the voltage range. When the sensor output SSA is higher than the first voltage V1, the output Sp of the first voltage comparator 594 becomes H level, while when the sensor output SSA is lower than the second voltage V2, the second voltage V2 is output. The output Sn of the voltage comparator 596 becomes H level. The excitation interval signal Ea is a signal obtained by taking the logical sum of these output signals Sp and Sn. Therefore, as shown in the lower part of FIG. 13B, the excitation interval signal Ea can be used as a signal indicating the excitation interval EP and the non-excitation interval NEP. The excitation interval EP and the non-excitation interval NEP are set by the CPU 110 adjusting the variable resistance value Rv.

  FIG. 14 compares various signal waveforms when the motor of this embodiment described above is driven with a rectangular wave and when driven with a sine wave (for the sake of explanation, the back electromotive force waveform is also referred to as a sine wave). Show. In the case of rectangular wave driving, a rectangular wave driving voltage is applied to the coil. The drive current is close to a rectangular wave at the start, but decreases as the rotational speed increases. This is because the counter electromotive force increases as the rotational speed increases (FIG. 2). However, in the rectangular wave driving, even if the rotation speed increases, the current value in the vicinity of the timing (phase = nπ) at which the driving voltage is switched does not decrease so much, and a considerably large current tends to flow.

  On the other hand, when driving with a sine wave, the drive voltage is PWM-controlled so that the effective value of the drive voltage has a sine wave shape. The drive current is close to a sine wave at the start, but when the rotational speed increases, the drive current decreases due to the influence of the counter electromotive force. In the sine wave drive, the current value is greatly reduced in the vicinity of the timing (phase = nπ) at which the polarity of the drive voltage is switched. As described with reference to FIG. 2, generally, the energy conversion efficiency of the motor is low near the timing at which the polarity of the drive voltage is switched. In the sine wave drive, the current value in the period of low efficiency is smaller than that in the rectangular wave drive, so that the motor can be driven with higher efficiency.

  FIG. 15 shows another configuration example of the A-phase driver circuit 120A and the B-phase driver circuit 120B included in the driver circuit 150 (FIG. 6). In the driver circuits 120A and 120B, an amplifier circuit 122 is provided in front of the gate electrodes of the transistors constituting the driver circuits 120A and 120B shown in FIG. Although the transistor type is also different from that in FIG. 7, any type of transistor can be used. In order to drive the motor of this embodiment in a wide operating range with respect to torque and rotation speed, it is preferable that the power supply voltage VDD of the driver circuits 120A and 120B can be set variably. When the power supply voltage VDD is changed, the levels of the drive signals DRVA1, DRVA2, DRVB1, DRVB2 given to the gate voltages of the transistors are also changed in proportion thereto. In this way, the motor can be driven using the power supply voltage VDD in a wide range. The amplifier circuit 122 is a circuit for changing the levels of the drive signals DRVA1, DRVA2, DRVB1, DRVB2. Note that the power supply unit 300 of the drive circuit unit 500 shown in FIG. 6 preferably supplies a variable power supply voltage VDD to the driver circuit 150.

  FIG. 16 shows the rotational speed of the motor of this embodiment when there is no load. As can be understood from this graph, the motor of this embodiment rotates at an extremely stable rotational speed up to an extremely low rotational speed when there is no load. This is because cogging does not occur because there is no magnetic core.

  FIG. 17 is a diagram illustrating an internal configuration of the regeneration control unit 200 and the rectifier circuit 250 illustrated in FIG. 6. Regenerative control unit 200 includes an A-phase charge switching unit 202, a B-phase charge switching unit 204, and an electronic variable resistor 206 connected to bus 102. Output signals of the two charge switching units 202 and 204 are given to input terminals of the two AND circuits 211 and 212, respectively.

  The A-phase charge switching unit 202 outputs a “1” level signal when recovering regenerative power from the A-phase coil 12A, and outputs a “0” level signal when not recovering. The same applies to the B-phase charge switching unit 204. Note that these signal levels are switched by the CPU 110. Further, the presence / absence of regeneration from the A-phase coil 12A and the presence / absence of regeneration from the B-phase coil 12B can be set independently. Therefore, for example, it is possible to regenerate electric power from the B-phase coil 12B while generating a driving force in the motor using the A-phase coil 12A.

  Similarly, the drive control unit 100 shown in FIG. 6 independently determines whether or not to generate a driving force using the A-phase coil 12A and whether or not to generate a driving force using the B-phase coil 12B. You may comprise so that it can set to. In this way, it is possible to operate the motor in an operation mode in which the driving force is generated on any one of the two-phase coils 12A and 12B while the power is regenerated on the other.

  The voltage across the electronic variable resistor 206 is applied to one of the two input terminals of the four voltage comparators 221 to 224. A phase sensor signal SSA and a phase B sensor signal SSB are supplied to the other input terminals of the voltage comparators 221 to 224. The output signals TPA, BTA, TPB, BTB of the four voltage comparators 221 to 224 can be called “mask signals” or “permission signals”.

  The mask signals TPA and BTA for the A phase coil are input to the OR circuit 231, and the mask signals TPB and BTB for the B phase are input to the other OR circuit 232. The outputs of these OR circuits 231 and 232 are given to the input terminals of the two AND circuits 211 and 212 described above. The output signals MSKA and MSKB of these AND circuits 211 and 212 are also called “mask signals” or “permission signals”.

  By the way, the configuration of the four voltage comparators 221 to 224 and the OR circuits 231 and 232 is the same as that in which two voltage comparators 594 and 596 and two OR circuits 598 in the excitation interval setting unit 590 shown in FIG. It is. Therefore, the output signal of the A-phase coil OR circuit 231 has the same waveform as the excitation interval signal Ea shown in FIG. When the output signal of the A-phase charge switching unit 202 is “1” level, the mask signal MSKA output from the AND circuit 211 for the A-phase coil is the same as the output signal of the OR circuit 231. These operations are the same for the B phase.

  The rectifier circuit 250 includes a full-wave rectifier circuit 252 including a plurality of diodes, two gate transistors 261 and 262, a buffer circuit 271 and an inverter circuit 272 (NOT circuit) as a circuit for the A-phase coil. ing. The same circuit is provided for the B phase. The gate transistors 261 and 262 are connected to a power supply wiring 280 for regeneration. Further, as the plurality of diodes, it is preferable to use Schottky diodes excellent in low Vf characteristics.

  The AC power generated by the A-phase coil 12A during power regeneration is rectified by the full-wave rectifier circuit 252. A gate signal of the A-phase coil and its inverted signal are given to the gates of the gate transistors 261 and 262, and the gate transistors 261 and 262 are controlled to be turned on / off accordingly. Accordingly, when at least one of the mask signals TPA and BTA output from the voltage comparators 221 and 222 is at the H level, the regenerative power is output to the power supply wiring 280, while both the mask signals TPA and BTA are at the L level. Then, power regeneration is prohibited.

  As can be understood from the above description, it is possible to recover the regenerative power using the regenerative control unit 200 and the rectifier circuit 250. In addition, the regeneration control unit 200 and the rectifier circuit 250 collect the regenerative power from the A-phase coil 12A and the B-phase coil 12B in accordance with the mask signal MSKA for the A-phase coil and the mask signal MSKB for the B-phase coil. And the amount of regenerative power can be adjusted accordingly.

  As described above, in the brushless motor of the first embodiment, the shaft portion 64 is fixed to the stator portion 10, the rotor portion 30 rotates around the shaft portion 64, and a driven member such as the wheel portion 71 is attached to the rotor portion 30. Since they are connected, the driven member can be rotated without rotating the central axis of the motor.

C. Modification of the motor configuration of the first embodiment:
FIG. 18 is an explanatory diagram showing another example of the motor configuration of the first embodiment. In the first embodiment, the wheel portion 71 is attached to the outer peripheral portion of the motor. Instead, it is also possible to attach a gear 71b and use the motor main body as a part of the gear (FIG. 18A). ). Moreover, it is also possible to attach the pulley 71c instead of the gear 71b (FIG. 18B).

D. Motor Configuration of Second Embodiment FIG. 19 is an explanatory diagram showing a motor configuration of the second embodiment. The only difference from the first embodiment shown in FIG. 1 is that the permanent magnet 32 and the coil 12 are provided only on one side of the support member 14, and the other configuration is the same as that of the first embodiment. Thus, even with a single-sided excitation motor, the driven member can be rotated without rotating the central axis of the motor.

E. Motor Configuration of Third Embodiment FIG. 20 is an explanatory diagram showing the configuration of the motor of the third embodiment. The only difference from the first embodiment shown in FIG. 1 is that the permanent magnet 32 is disposed on the outer peripheral side of the coil 12, and the other configuration is the same as that of the first embodiment (FIG. 20A). )). Further, instead of the wheel portion 71, a blade 71d may be attached to form a fan motor (FIG. 20B). As described above, even if the arrangement of the permanent magnet 32 and the coil 12 is the same as that of the outer rotor type motor, the driven member can be rotated without rotating the central axis of the motor.

F. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

F1. Modification 1:
Although the two-phase brushless motor has been described in the above embodiments and modifications, the present invention can be applied to a brushless motor having an arbitrary number of phases M (M is an integer of 1 or more). Moreover, although the coil group of each phase should just contain at least 1 electromagnetic coil, it is preferable that 2 or more electromagnetic coils are included.

F2. Modification 2:
In the above embodiment, an analog magnetic sensor is used, but a digital magnetic sensor having a multi-valued analog output may be used instead of the analog magnetic sensor. An analog magnetic sensor and a digital magnetic sensor having a multi-value output are common in that they have an output signal indicating an analog change. In this specification, “an output signal indicating an analog change” includes both a digital output signal having multiple levels of three or more and an analog output signal, not an on / off binary output. Used in a broad sense.

  A digital magnetic sensor having a binary digital output may be used instead of a sensor having an output signal indicating an analog change. In this case, the ADC unit 570 and the excitation interval setting unit 590 in FIG. 8 are not necessary. Therefore, since the excitation interval is not set and the sinusoidal drive waveform is not used, the efficiency is lowered and vibration / noise is generated. However, the drive control circuit can be realized with an inexpensive IC.

F3. Modification 3:
As the PWM circuit, various circuit configurations other than the circuit shown in FIG. 10 can be adopted. For example, a circuit that performs PWM control by comparing the sensor output with a reference triangular wave may be used. Further, the drive signal may be generated by a method other than PWM control. A circuit that generates a drive signal by a method other than PWM control may be employed. For example, it is possible to employ a circuit that amplifies the sensor output and generates an analog drive signal.

  In FIG. 8, the ADC unit 570 can be changed to a voltage comparator (comparator). In this case, since the rectangular wave drive is used instead of the sine wave drive waveform, the efficiency is reduced and vibration / noise is generated. However, the drive control circuit can be realized with an inexpensive IC.

F4. Modification 4:
The present invention is also applicable to a motor that does not include a regenerative circuit and a generator that does not include a drive control circuit. Specific examples include, for example, an auto head of a projector, an auto head of a video camera, an electric vehicle, an airship, a helicopter, a jet engine (pressurizing unit), a robot, a fan motor, a clock (hand drive), and a drum type washing machine. (Single rotation), can be applied to motors of various devices such as roller coasters, vibration motors, and toys.

  FIG. 21 is an explanatory view showing a railway vehicle using a motor according to an embodiment of the present invention. This railway vehicle 1000 has a motor 1010 and wheels 1020. The motor 1010 drives the wheel 1020. Further, the motor 1010 is used as a generator during braking of the railway vehicle 1000 to regenerate electric power. As the motor 1010, the various brushless motors described above can be used.

F5. Modification 5:
In the above embodiment, the fixing screw portion 50 for attachment and detachment is provided, but the wheel portion 70 and the rotor portion 30 may be integrally formed without the fixing screw portion 50.

It is sectional drawing which shows the structure of the motor main body of the electric motor in 1st Example. It is explanatory drawing which shows the relationship between a magnetic sensor output and the back electromotive force waveform of a coil. It is a schematic diagram which shows the relationship between the applied voltage of a coil, and a counter electromotive force. It is explanatory drawing which shows the mode of the normal rotation operation | movement of the motor of 1st Example. It is explanatory drawing which shows the mode of reverse rotation operation | movement of the motor of 1st Example. It is a block diagram which shows the structure of the drive circuit unit of a motor. It is a figure which shows the internal structure of a driver circuit. It is explanatory drawing which shows the internal structure and operation | movement of a drive control part. It is explanatory drawing which shows the correspondence of a sensor output waveform and a drive signal waveform. It is a block diagram which shows the internal structure of a PWM part. It is a timing chart which shows operation | movement of the PWM part at the time of motor forward rotation. It is a timing chart which shows operation | movement of the PWM part at the time of motor reverse rotation. It is explanatory drawing which shows the internal structure and operation | movement of an excitation area setting part. It is explanatory drawing which compares and shows the various signal waveforms at the time of driving the motor of 1st Example with a rectangular wave, and driving with a sine wave. It is a figure which shows the other structure of a driver circuit. It is a graph which shows the rotation speed at the time of no load of the motor of an Example. It is a figure which shows the internal structure of a regeneration control part and a rectifier circuit. It is explanatory drawing which shows the other example of the motor structure of 1st Example. It is explanatory drawing which shows the motor structure of 2nd Example. It is explanatory drawing which shows the structure of the motor of 3rd Example. It is explanatory drawing which shows the rail vehicle using the motor by the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Stator part 12A, 12B ... Electromagnetic coil 14 ... Support member 30 ... Rotor part 30U ... Upper rotor part 30L ... Lower rotor part 31U ... Upper rotation casing part 31L. .. Lower rotating casing 32 ... Permanent magnet 32L ... Permanent magnet 32U ... Permanent magnet 34U, 34L ... Magnetic yoke 40A, 40B ... Magnetic sensor 50 ... Fixing screw 64 .. .Shaft (center axis)
64a ... shaft fixing portion 64e ... shaft end fixing member 65U, 65L ... bearing portion 70 ... wheel portion 70c ... sealing cap 71 ... wheel portion 71b ... gear 71c .. .Pulley 71d ... blade 100 ... drive control unit 102 ... bus 110 ... CPU
120A, 120B ... Driver circuit 122 ... Amplifier circuit 150 ... Driver circuit 200 ... Regenerative control unit 202,204 ... Charge switching unit 206 ... Electronic variable resistor 211,212 ... AND circuits 221 to 224 ... voltage comparators 231, 232 ... OR circuits 250 ... rectifier circuits 252 ... full-wave rectifier circuits 261, 262 ... gate transistors 271 ... buffer circuits 272 .. .Inverter circuit 278 ... drive power line 279 ... control line 280 ... power supply wiring 500 ... drive circuit unit 510 ... basic clock generation circuit 520 ... frequency divider 530 ... PWM unit 531 ... Counter 533 ... EXOR circuit 535 ... Drive waveform forming unit 540 ... Register 550 ... Multiplier 560 ... Encoding unit 570 ... AD conversion unit 580 ... Command value Register 590 ... Excitation section setting section 592 ... Electronic variable resistor 59 4,596 ... Voltage comparator 598 ... OR circuit 1000 ... Rail car 1010 ... Motor 1020 ... Wheel

Claims (11)

A brushless motor for driving a driven member ,
A stator having an A-phase coil group, a B-phase coil group, and a position sensor;
A shaft portion fixed to the stator;
While rotating around the front Kijiku portion, and which are connected to the driven member rotor,
A drive circuit unit that is provided in the stator and generates a drive signal for driving the brushless motor;
Wiring provided in at least a part of the inside of the shaft portion and connected to the drive circuit unit;
Equipped with a,
The rotor has a first rotor and a second rotor connected to the first rotor and fixed in a relative position with respect to the first rotor;
The first rotor and the second rotor sandwich the stator,
The first rotor has a first permanent magnet group and is disposed on one side of the stator,
The second rotor has a second permanent magnet group and is disposed on the other side of the stator,
The stator has a first surface and a second surface that is a surface opposite to the first surface;
The A-phase coil group is disposed on the first surface of the stator, but is not disposed on the second surface,
The B phase coil group is disposed on the second surface of the stator, but is not disposed on the first surface,
The A phase coil group and the B phase coil group are arranged with an electrical angle shifted by π / 2,
The A phase and B phase coil groups do not have a magnetic core,
The number of permanent magnets included in the first permanent magnet group is equal to the number of electromagnetic coils included in the A-phase coil group,
The number of permanent magnets included in the second permanent magnet group is equal to the number of electromagnetic coils included in the B-phase coil group,
The number of permanent magnets included in the first permanent magnet group is equal to the number of permanent magnets included in the second permanent magnet group;
The permanent magnets included in the first permanent magnet group are each arranged at a constant magnetic pole pitch, and the adjacent permanent magnets are magnetized in opposite directions,
The permanent magnets included in the second permanent magnet group are each arranged at a constant magnetic pole pitch, and the adjacent permanent magnets are magnetized in opposite directions,
The permanent magnets included in the first and second permanent magnet groups are arranged such that the magnetic poles directed to the stator have different polarities,
The pitch of the permanent magnets included in the first and second permanent magnet groups is equal to the pitch of the coils belonging to the A phase and B phase coil groups,
The direction of the magnetic flux of the first and second permanent magnet groups is perpendicular to the stator;
An AC drive signal is supplied as the drive signal to the A-phase and B-phase coil groups.
Brushless motor. The brushless motor according to claim 1,
The rotor has a shape that wraps the stator inside,
The first and second permanent magnet groups are brushless motors provided in an inner portion of the rotor. The brushless motor according to claim 1 or 2,
The position sensor is a brushless motor including a magnetic sensor that outputs an output signal indicating an analog change according to a relative position between the stator and the rotor. The brushless motor according to claim 3,
The drive circuit unit is
A brushless motor including a PWM control circuit that generates a drive signal that simulates an analog change in the output signal of the magnetic sensor by executing PWM control using an analog change in the output signal of the magnetic sensor. The brushless motor according to claim 4,
The drive circuit unit is
A brushless motor including a regenerative circuit for regenerating power from the A-phase and B-phase coil groups . The brushless motor according to claim 5,
A brushless motor, wherein wiring for recovering regenerative power from the regenerative circuit is provided inside the shaft portion. The brushless motor according to any one of claims 4 to 6,
A brushless motor in which at least a part of the A-phase and B-phase coil groups , the position sensor, and the drive circuit unit is covered with resin. The brushless motor according to any one of claims 1 to 7,
A driven member driven by the brushless motor;
A device comprising: The apparatus according to claim 8, comprising:
The device is a moving body. The apparatus of claim 9, comprising:
The apparatus, wherein the moving body is a railway vehicle.   A robot comprising the brushless motor according to any one of claims 1 to 7.

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