JP2013051880A - Brushless electrical machine and device, mobile object, electric generator, and robot including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which improves the utilization efficiency of a magnetic field in a brushless electrical machine and thereby improving the efficiency of the electrical machine.SOLUTION: A brushless electrical machine of this invention has: a first driving member 30U having multiple permanent magnets 32U; a second driving member 10 having multiple electromagnetic coils and moving relative to the first driving member 30U; and a third driving member 30L which is disposed at the opposite side of the first driving member 30U across the second driving member 10 and having the fixed relative positional relationship with the first driving member 30U. The second driving member 10 includes magnetic sensors 40A, 40B detecting the relative position of the first driving member and the second driving member and a control circuit utilizing output signals of the magnetic sensors and controlling the brushless electrical machine. The third driving member 30L has magnetic field strengthening members 32L, strengthening a magnetic field at a position of the second driving member 10 in cooperation with the respective permanent magnets of the first driving member 30U, at positions which face the respective permanent magnets of the first driving member 30U.

Description

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

  As a brushless electric machine 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

  FIG. 26 is a conceptual diagram showing an example of the configuration of a conventional brushless motor. This brushless motor includes an electromagnetic coil array 12 and a magnet array 32. A magnetic field is illustrated in the vicinity of the magnet array 32. In the conventional brushless motor, since the magnetic field by the permanent magnet is in an open state, the use efficiency of the magnetic field by the electromagnetic coil array 12 is considerably low. Such a problem is not only a motor but also a problem common to generators, and is generally a problem common to brushless electric machines.

  An object of the present invention is to provide a technique for improving the efficiency of an electric machine by increasing the use efficiency of a magnetic field in a brushless electric machine.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A brushless electric machine,
A first drive member having a plurality of permanent magnets;
A second drive member having a plurality of electromagnetic coils and movable relative to the first drive member;
A third drive member disposed on the opposite side of the first drive member across the second drive member, the relative positional relationship with the first drive member being fixed;
A magnetic sensor provided on the second driving member for detecting a relative position of the first and second driving members;
A control circuit for controlling the operation of the brushless electric machine using an output signal of the magnetic sensor;
With
The third driving member has a magnetic field strengthening member that strengthens the magnetic field at the position of the second driving member in cooperation with each permanent magnet at a position facing each permanent magnet of the first driving member. Brushless electric machine.

  According to this configuration, since the permanent magnet and the magnetic field enhancing member strengthen the magnetic field jointly, it is possible to increase the use efficiency of the magnetic field by the permanent magnet and improve the efficiency of the electric machine.

[Application Example 2]
A brushless electric machine according to Application Example 1,
The brushless electric machine, wherein the magnetic field enhancing member is a permanent magnet.

  According to this configuration, since the second drive member is sandwiched from above and below by the permanent magnet, the magnetic field at the position of the second drive member can be extremely increased.

[Application Example 3]
A brushless electric machine according to Application Example 1,
The magnetic field enhancing member is a brushless electric machine made of a ferromagnetic material.

  According to this configuration, the magnetic field at the position of the second driving member can be strengthened using fewer permanent magnets.

[Application Example 4]
The brushless electric machine according to any one of Application Examples 1 to 3,
Each permanent magnet is a brushless electric machine having a protrusion protruding to the side facing the second drive member.

  According to this configuration, the magnetic field near the protrusion can be further increased.

[Application Example 5]
The brushless electric machine according to any one of Application Examples 1 to 4,
The plurality of electromagnetic coils have a coil group of M phases (M is an integer of 2 or more) each having N (N is an integer of 1 or more) electromagnetic coils,
The control circuit is a brushless electric machine that drives the M-phase coil group so that the M-phase coil group generates a driving force at the same time.

  According to this configuration, since the M-phase coil group simultaneously generates a driving force, a large driving force can be generated.

[Application Example 6]
The brushless electric machine according to any one of Application Examples 1 to 5,
The magnetic sensor is a brushless electric machine that outputs an output signal indicating an analog change in accordance with a relative position of the first and second driving members.

  According to this configuration, it is possible to efficiently drive the brushless electric machine using the analog change of the magnetic sensor.

[Application Example 7]
A brushless electric machine according to Application Example 6,
The control circuit includes 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. Brushless electric machine.

  According to this configuration, since the brushless electric machine 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.

[Application Example 8]
The brushless electric machine according to any one of Application Examples 1 to 7,
The brushless electric machine, wherein the control circuit includes a regenerative circuit that regenerates electric power from the electromagnetic coil.
According to this structure, it is possible to generate electric power using a brushless electric machine.

  The present invention can be realized in various forms, for example, in the form of a brushless motor, a brushless generator, a control method (or drive method) thereof, an actuator using the same, or a power generator. can do.

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 explanatory drawing which shows the relationship between the use of the electric machine of an Example, and a preferable material. 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 showing other composition 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 motor structure of the 1st modification of 1st Example. It is explanatory drawing which shows the motor structure of the 2nd modification of 1st Example. It is explanatory drawing which shows the mode of the normal rotation operation | movement of a three-phase brushless motor. It is explanatory drawing which shows the structure of the three-phase linear motor of the 3rd modification of 1st Example. It is sectional drawing which shows the structure of the motor main body of the electric motor in 2nd Example. It is explanatory drawing which shows the mode of the normal rotation operation | movement of the motor of 2nd Example. It is explanatory drawing which shows the motor structure of the 1st modification of 2nd Example. It is a conceptual diagram which shows an example of a structure of the conventional brushless motor. It is explanatory drawing which shows the projector using the motor by the Example of this invention. It is explanatory drawing which shows the fuel cell type mobile telephone using the motor by the Example of this invention. It is explanatory drawing which shows the electric bicycle (electric assisted bicycle) as an example of the moving body using the motor / generator by the Example of this invention. It is explanatory drawing which shows an example of the robot using the motor by the Example of this invention.

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. Overview of motor configuration and operation of the second embodiment:
E. 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. This motor body has a stator portion 10, an upper rotor portion 30U, and a lower rotor portion 30L. Each of these members 10, 30U, 30L has a substantially disk shape. FIG. 1B is a horizontal sectional view of the lower rotor portion 30L. The lower rotor portion 30L includes four permanent magnets 32L each having a substantially fan shape. Since the upper rotor portion 30U has the same configuration as the lower rotor portion 30L, the illustration is omitted. The upper rotor portion 30U and the lower rotor portion 30L are fixed to the central shaft 64 and rotate simultaneously. The magnetization directions of the magnets 32U and 32L are parallel to the rotation axis 64.

  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 B-phase coil 12B side. In this example, four B-phase coils 12B are provided, each wound in a substantially fan shape. The same applies to the A-phase coil 12A. The stator unit 10 is further provided with a drive circuit unit 500. As shown in FIG. 1A, the stator portion 10 is fixed to the casing 62.

  FIG. 1D is a conceptual diagram showing the relationship between the stator portion 10 and the two rotor portions 30U and 30L. 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 A-phase sensor 40A is arranged with the B-phase coil 12B on the lower surface of the support member 14, but may instead be arranged on the upper surface of the support member 14. The same applies to the B-phase sensor 40B. As can be understood from FIG. 1C, in this embodiment, since the A-phase sensor 40A is arranged inside the B-phase coil 12B, there is an advantage that it is easy to secure a space for arranging the sensor 40A.

  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 the open magnetic field shown in FIG. 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.

  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 and the motor is driven, a counter 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 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 improves. 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.

FIG. 6 shows the relationship between the use of an electric machine as an embodiment of the present invention and a preferred material. For example, there are uses that give priority to the following items.
(1) The price is low.
(2) It must be small.
(3) Low power consumption.
(4) Durability against vibration and impact.
(5) Usability in high temperature environment.
(6) It must be lightweight.
(7) A large torque can be generated.
(8) High rotation is possible.
(9) Be environmentally friendly.

  In the right column of each application in FIG. 6, permanent magnets, rotor materials (support members for the rotor portions 30U and 30L), bobbin materials (coil core materials), and materials suitable for the case materials are shown. ing. The “expensive magnet” means a neodymium magnet, a samarium cobalt magnet, an alnico magnet, or the like. “General resin” means various resins (especially synthetic resins) excluding carbon-based resins and vegetable resins. “Carbon-based resin” means glassy carbon (carbon fiber reinforced resin (CFRP), carbon fiber, etc.) As metals for rotor materials, aluminum, stainless steel, titanium, magnesium, copper, silver, gold Fine ceramics, steatite ceramics, alumina, zircon, and glass can be used as “ceramics”, and plants and wood can be used as “natural materials”. In addition, materials using earth and sand (for example, vegetable resin) can be used.

  As can be understood from these examples, in the electric machine as the embodiment of the present invention, various nonmagnetic and nonconductive materials can be used as the rotor material, bobbin material (core material), and case material. Is possible. However, a metal material such as aluminum or an alloy thereof may be used as the rotor material in consideration of strength. Also in this case, it is preferable that the bobbin material and the case material are made of a substantially non-magnetic and non-conductive material. Here, “substantially non-magnetic and non-conductive material” means that a small part is allowed to be a magnetic substance or a conductor. For example, whether or not the bobbin material is formed of a substantially non-magnetic non-conductive material can be determined by whether or not cogging exists in the motor. Further, whether or not the case material is formed of a substantially non-conductive material is determined by whether or not the iron loss (eddy current loss) due to the case material is equal to or less than a predetermined value (for example, 1% of input). be able to.

  In addition, among structural materials for electric machines, there are also members that are preferably made of a metal material, such as a rotating shaft and a bearing portion. Here, the “structural material” means a member used to support the shape of the electric machine, and means a main member that does not include a small part or a fixture. Rotor material and case material are also a kind of structural material. In the electric machine of the embodiment, the main structural material other than the rotating shaft and the bearing portion can be formed of a nonmagnetic and nonconductive material.

B. Configuration of drive circuit unit:
FIG. 7 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. 7, 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. 8 shows the configuration of the A-phase driver circuit 120A and the B-phase driver circuit 120B included in the driver circuit 150 (FIG. 7). 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.

  FIG. 9 is an explanatory diagram showing the internal configuration and operation of the drive control unit 100 (FIG. 7). 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. Note that the drive control unit 100 is a circuit that generates both the A-phase drive signal and the B-phase drive signal, but only the A-phase circuit configuration is illustrated in FIG. 9A for convenience of illustration. ing. For the B phase, the same circuit as the A phase is 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. 8) 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.

  FIGS. 9B to 9E 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. 9B to 9E, 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 positive. However, these are described together in FIGS. For convenience, the second drive signal DRVA2 is drawn as a negative pulse.

  FIGS. 10A to 10C are explanatory diagrams illustrating the 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 in FIG. 9, 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. 10C 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. 10B 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 near the middle point of the back electromotive force waveform (that is, near 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. 7). 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. 11 is a block diagram illustrating an example of an internal configuration of the PWM unit 530 (FIG. 9). The PWM unit 530 includes a counter 531, an EXOR circuit 533, and a drive waveform forming unit 535. These operate as follows.

  FIG. 12 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. 12, 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, of the output S1 of the counter 531, the signal during the period when 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 when the output S2 is at the H level is output as the second drive signal DRVA2. Output as. In the vicinity of the right end of FIG. 12, 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. 13 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, it can be understood that the two drive signals DRVA1 and DRVA2 are interchanged from FIG. 12, and as a result, the motor reverses.

  FIG. 14 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. 14B 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. 14B, 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. 15 shows various signal waveforms when the motor of this embodiment described above is driven by a rectangular wave and when it is driven by a sine wave. 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. 16 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. 7). 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 shown in FIG. 8, 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. 7 preferably supplies a variable power supply voltage VDD to the driver circuit 150.

  FIG. 17 shows the rotation 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.

  18 is a diagram illustrating an internal configuration of the regeneration control unit 200 and the rectifier circuit 250 illustrated in FIG. 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 can independently set whether to generate a driving force using the A-phase coil 12A and whether to generate a driving force using the B-phase coil 12B. It may be configured. 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. Accordingly, 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.

  AC power generated by the A-phase coil 12 </ b> A 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 according to 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, the brushless motor of the first embodiment employs a configuration in which both sides of a plurality of electromagnetic coils are sandwiched between permanent magnets, so that the magnetic field at the position of the electromagnetic coils can be strengthened and efficiency can be increased. .

C. Modification of the motor configuration of the first embodiment:
FIG. 19 is an explanatory diagram showing a configuration of a brushless motor as a first modification of the first embodiment. In the rotor portions 30Ua and 30La of the brushless motor, convex portions 36 (FIG. 22B) protruding toward the stator portion 10 are provided at the center portions of the permanent magnets 32Ua and 32Ub, respectively. Other configurations are the same as those of the motor shown in FIG. The convex portion 36 at the center of the permanent magnets 32Ua and 32Ub has a width corresponding to the effective coil portion ECP of the coils 12A and 12B shown in FIG. The effective coil portion ECP of the coils 12A and 12B is a coil portion that generates an effective driving force, and the other coil portions generate little driving force (force in the rotational direction in a rotary motor). Therefore, it is possible to more effectively utilize the magnetic field of the magnet by providing each permanent magnet with a convex portion 36 having substantially the same width as the effective coil portion ECP.

  FIG. 20 is an explanatory diagram showing a configuration of a three-phase brushless motor as a second modification of the first embodiment. This brushless motor is different from the motor shown in FIG. 1 in that the stator portion 10a has a three-phase coil, and the configurations of the rotor portions 30U and 30L are the same as those in FIG. As shown in FIG. 20D, the stator portion 10a has a three-layer structure of an A-phase coil 12A, a B-phase coil 12B, and a C-phase coil 12C. These three-phase coils 12A, 12B, and 12C are arranged with a phase difference of 2π / 3. 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 middle position between the two B-phase coils 12B, and the C-phase sensor 40C is also arranged at the middle position between the two C-phase coils 12C. It is not necessary to arrange the coils for three phases in a three-layer structure, and for example, it is possible to arrange them in a one-layer structure (that is, on the same surface). However, if the three-layer structure is adopted, more coils can be arranged, which has an advantage that a large torque can be generated.

  21 (A) to 21 (C) are explanatory views showing the state of forward rotation of the three-phase brushless motor of FIG. FIGS. 21A to 21C show states immediately before the phases are 0, 2π / 3, and 4π / 3, respectively. In the three-phase drive, as is well known, the excitation direction of any phase is reversed every π / 3 period. A description of the reverse operation of the three-phase brushless motor is omitted.

  FIG. 22 shows a configuration of a three-phase linear motor as a third modification of the first embodiment. The linear motor 1000 includes a fixed guide part 1100 and a moving part 1200. As shown in FIG. 22A, a large number of permanent magnets 32 are arranged along the moving direction on the upper and lower portions of the fixed guide portion 1100, respectively. The moving part 1200 is provided at a position sandwiched by these permanent magnets 32 in the vertical direction, and three-phase coils 12A, 12B, and 12C are provided. A magnetic sensor is provided between adjacent coils of each phase, but is not shown here. As shown in FIG. 22B, the moving unit 1200 is provided with a drive control unit 1250. The drive controller 1250 has a self-supporting power supply device (not shown) such as a fuel cell. The moving part 1200 is slidably held on the fixed guide part 1100 by a bearing part 1140. The embodiment of the present invention can also be realized as such a linear motor. The linear motor can be configured as a two-phase brushless motor.

D. Overview of motor configuration and operation of the second embodiment:
FIGS. 23A to 23D are cross-sectional views showing the configuration of the motor body of the brushless motor as the second embodiment of the present invention. This motor body is obtained by changing the configuration of the lower rotor portion 30L of the motor shown in FIG. 1, and the other configurations are the same as those in FIG. As shown in FIGS. 23A and 23D, the lower rotor portion 30Lb is provided with a magnetic yoke 38 formed of a ferromagnetic material instead of a permanent magnet. These magnetic yokes 38 have a function of strengthening the magnetic field (in particular, the magnetic field at the position of the stator unit 10) by the permanent magnet 32 of the upper rotor unit 30U.

  As can be understood from the first and second embodiments, a permanent magnet is provided on one side of both sides of the coil, and a magnetic field enhancing member for strengthening the magnetic field at the coil position is provided on the other side in cooperation with the permanent magnet. Is possible. In the first embodiment shown in FIG. 1, the permanent magnet 32L functions as a magnetic field enhancing member, and in the second embodiment shown in FIG. 23, the magnetic yoke 38 functions as a magnetic field enhancing member. In these configurations, since the magnetic field at the coil position is strengthened, the use efficiency of the magnetic field in the brushless motor can be increased and the motor efficiency can be improved.

  As shown in FIG. 23D, the same number of magnetic yokes 38 as the permanent magnets 32U may be provided at positions facing the individual permanent magnets 32U, or opposed to a plurality of permanent magnets. Such a plate-shaped magnetic yoke may be used. In the latter case, it is possible to use one flat yoke member as a magnetic field enhancing member for a plurality of permanent magnets. As shown in FIG. 23D, each magnetic yoke 38 preferably has a convex portion at a position facing each individual permanent magnet 32U.

  FIGS. 24A to 24D are explanatory views showing the reverse operation of the brushless motor of the second embodiment. 24A to 24D show states in which the phases are immediately before 0, π / 2, π, and 3π / 2, respectively. This operation is basically the same as that shown in FIG. The reverse operation is the same as that shown in FIG.

  FIG. 25 is an explanatory diagram showing a motor configuration of a first modification of the second embodiment. The brushless motor 2000 is configured as a fan motor. That is, the blades 2100 are fixed to the outer peripheral portion of the upper rotor portion 30Ub. The permanent magnet 32Ub of the upper rotor portion 30Ub has a convex portion protruding toward the stator portion 10. This convex part is a device for further improving the motor efficiency as described in FIG.

  The brushless motor of the second embodiment can also be realized as a three-phase motor shown in FIG. 20 or a linear motor shown in FIG.

  By the way, in the linear motor of FIG. 22, the member in which the electromagnetic coil is provided moves, and the member in which the permanent magnet is provided is fixed. This relationship is the reverse of the configuration shown in FIGS. That is, in the motor shown in FIG. 1, a member (stator portion 10) provided with an electromagnetic coil is fixed, and a member (rotor portions 30U, 30L) provided with a permanent magnet (or magnetic yoke 38). Move. As can be understood from these examples, the electric machine according to the embodiment of the present invention is provided with a first member (also referred to as a “first driving member”) provided with a permanent magnet and an electromagnetic coil. A second member (also referred to as “second drive member”) and a third member (also referred to as “third drive member”) provided with a magnetic field enhancing member (permanent magnet 32L or magnetic yoke 38). The first and third drive members can be realized as various electric machines configured to move relative to the second drive member.

E. 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.

E1. Modification 1:
In the above-described embodiments and modifications, the two-phase brushless motor and the three-phase brushless motor have been described. However, 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). For example, the present invention can be applied to a single-phase motor. The one-phase motor can be realized, for example, by omitting one phase of the two-phase coils of the motor shown in FIG. In addition, 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.

E2. 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. 9 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.

E3. Modification 3:
As the PWM circuit, various circuit configurations other than the circuit shown in FIG. 11 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. 9, 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.

E4. 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 are applicable to motors of various devices such as a fan motor, a timepiece (hand drive), a drum-type washing machine (single rotation), a roller coaster, and a vibration motor. When the present invention is applied to a fan motor, various effects (low power consumption, low vibration, low noise, low rotation unevenness, low heat generation, long life) are particularly remarkable. Such fan motors are, for example, various devices such as digital display devices, in-vehicle devices, fuel cell computers, fuel cell digital cameras, fuel cell video cameras, fuel cell mobile phones, and other fuel cell equipment. It can be used as a fan motor for the device. The motor of the present invention can also be used as a motor for various home appliances and electronic devices. For example, the motor according to the present invention can be used as a spindle motor in an optical storage device, a magnetic storage device, a polygon mirror drive device, or the like. The motor according to the present invention can also be used as a motor for a moving body or a robot.

  FIG. 27 is an explanatory diagram showing a projector using a motor according to an embodiment of the present invention. The projector 600 includes three light sources 610R, 610G, and 610B that emit light of three colors of red, green, and blue, and three liquid crystal light valves 640R, 640G, and 640B that modulate these three colors of light, respectively. A cross dichroic prism 650 that synthesizes the modulated three-color light, a projection lens system 660 that projects the combined three-color light onto the screen SC, a cooling fan 670 for cooling the inside of the projector, and the projector 600 And a control unit 680 for controlling the whole. As the motor for driving the cooling fan 670, the various brushless motors described above can be used.

  FIGS. 28A to 28C are explanatory views showing a fuel cell type mobile phone using a motor according to an embodiment of the present invention. FIG. 28A shows the appearance of the mobile phone 700, and FIG. 28B shows an example of the internal configuration. The mobile phone 700 includes an MPU 710 that controls the operation of the mobile phone 700, a fan 720, and a fuel cell 730. The fuel cell 730 supplies power to the MPU 710 and the fan 720. The fan 720 is used to supply air to the fuel cell 730 from the outside to the inside of the mobile phone 700 or to discharge moisture generated by the fuel cell 730 from the inside of the mobile phone 700 to the outside. It is. Note that the fan 720 may be disposed on the MPU 710 as shown in FIG. 28C to cool the MPU 710. As the motor for driving the fan 720, the various brushless motors described above can be used.

  FIG. 29 is an explanatory diagram showing an electric bicycle (electric assist bicycle) as an example of a moving body using a motor / generator according to an embodiment of the present invention. In this bicycle 800, a motor 810 is provided on the front wheel, and a control circuit 820 and a rechargeable battery 830 are provided on a frame below the saddle. The motor 810 assists running by driving the front wheels using the power from the rechargeable battery 830. Further, the electric power regenerated by the motor 810 is charged to the rechargeable battery 830 during braking. The control circuit 820 is a circuit that controls driving and regeneration of the motor. As the motor 810, the various brushless motors described above can be used.

  FIG. 30 is an explanatory diagram showing an example of a robot using a motor according to the embodiment of the present invention. The robot 900 includes first and second arms 910 and 920 and a motor 930. The motor 930 is used when horizontally rotating the second arm 920 as a driven member. As the motor 930, the above-described various brushless motors can be used.

DESCRIPTION OF SYMBOLS 10 ... Stator part 12A, 12B, 12C ... Electromagnetic coil 14 ... Support member 30 ... Rotor part 30L ... Lower rotor part 30U ... Upper rotor part 32 ... Permanent magnet 32L ... Permanent magnet (magnetic field reinforcement member)
34U, 34L ... Magnetic yoke 36 ... Projection 38 ... Magnetic yoke (magnetic field enhancing member)
40A, 40B ... Magnetic sensor 62 ... Casing 64 ... Rotating shaft (center axis)
DESCRIPTION OF SYMBOLS 100 ... Drive control part 102 ... Bus 110 ... CPU
120A, 120B ... Driver circuit 122 ... Amplifier circuit 150 ... Driver circuit 200 ... Regeneration control unit 202, 204 ... Charge switching unit 206 ... Electronic variable resistor 211, 212 ... AND circuit 221-224 ... Voltage comparator 231, 232 ... OR Circuit 250 ... Rectifier circuit 252 ... Full wave rectifier circuit 261, 262 ... Gate transistor 271 ... Buffer circuit 272 ... Inverter circuit 280 ... Power supply wiring 500 ... Drive circuit unit 510 ... Basic clock generation circuit 520 ... Divider 530 ... PWM unit 531 ... Counter 533 ... EXOR circuit 535 ... Drive waveform forming unit 540 ... Register 550 ... Multiplier 560 ... Encoding unit 570 ... AD converter 580 ... Command value register 590 ... Excitation section setting unit 592 ... Electronic variable resistor 594,596 ... Voltage comparator 598 ... OR Road 600 ... projector 610R, 610G, 610B ... light source 640R, 640G, 640B ... liquid crystal light valves 650 ... cross dichroic prism 660 ... projection lens system 670 ... cooling fan 680 ... control unit 700 ... mobile phone 710 ... MPU
720 ... Fan 730 ... Fuel cell 800 ... Electric bicycle (Electric assist bicycle)
DESCRIPTION OF SYMBOLS 810 ... Motor 820 ... Control circuit 830 ... Rechargeable battery 900 ... Robot 910 ... Arm 920 ... Arm 930 ... Motor 1000 ... Linear motor 1100 ... Fixed guide part 1140 ... Bearing part 1200 ... Moving part 1250 ... Drive control part 2000 ... Brushless motor ( Fan motor)
2100 ... feather

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
A first aspect of the present invention is a brushless electric machine,
With permanent magnets,
An electromagnetic coil movable relative to the permanent magnet;
A magnetic field enhancing member disposed on the opposite side of the permanent magnet across the electromagnetic coil and having a fixed relative positional relationship with the permanent magnet;
With
The permanent magnet and the magnetic field strengthening member are arranged so that different magnetic poles face each other,
In the permanent magnet and the magnetic field strengthening member, the area of the first surface facing the electromagnetic coil is smaller than the area of the second surface opposite to the first surface .
According to this aspect, since the permanent magnet and the magnetic field enhancing member strengthen the magnetic field jointly, the use efficiency of the magnetic field by the permanent magnet can be increased and the efficiency of the electric machine can be improved.

C. Modification of the motor configuration of the first embodiment:
FIG. 19 is an explanatory diagram showing a configuration of a brushless motor as a first modification of the first embodiment. In the rotor portions 30Ua and 30La of the brushless motor, convex portions 36 (FIG. 19B ) protruding toward the stator portion 10 are provided at the center portions of the permanent magnets 32Ua and 32Ub, respectively. Other configurations are the same as those of the motor shown in FIG. Permanent magnets 32Ua, the convex portion 36 of the central 32Ub, the coil 12A shown in FIG. 19 (D), has a width corresponding to the effective coil portion ECP of 12B. The effective coil portion ECP of the coils 12A and 12B is a coil portion that generates an effective driving force, and the other coil portions generate little driving force (force in the rotational direction in a rotary motor). Therefore, it is possible to more effectively utilize the magnetic field of the magnet by providing each permanent magnet with a convex portion 36 having substantially the same width as the effective coil portion ECP.

Claims (10)

A brushless electric machine,
A first drive member having a plurality of permanent magnets;
A second drive member having a plurality of electromagnetic coils and movable relative to the first drive member;
A third drive member disposed on the opposite side of the first drive member across the second drive member, the relative positional relationship with the first drive member being fixed;
A magnetic sensor provided on the second driving member for detecting a relative position of the first and second driving members;
A control circuit for controlling the operation of the brushless electric machine using an output signal of the magnetic sensor;
With
The third driving member has a magnetic field strengthening member that strengthens the magnetic field at the position of the second driving member in cooperation with each permanent magnet at a position facing each permanent magnet of the first driving member. Brushless electric machine. The brushless electric machine according to claim 1,
The brushless electric machine, wherein the magnetic field enhancing member is a permanent magnet. The brushless electric machine according to claim 1,
The magnetic field enhancing member is a brushless electric machine made of a ferromagnetic material. A brushless electric machine according to any one of claims 1 to 3,
Each permanent magnet is a brushless electric machine having a protrusion protruding to the side facing the second drive member. A brushless electric machine according to any one of claims 1 to 4,
The plurality of electromagnetic coils have a coil group of M phases (M is an integer of 2 or more) each having N (N is an integer of 1 or more) electromagnetic coils,
The control circuit is a brushless electric machine that drives the M-phase coil group so that the M-phase coil group generates a driving force at the same time. A brushless electric machine according to any one of claims 1 to 5,
The magnetic sensor is a brushless electric machine that outputs an output signal indicating an analog change in accordance with a relative position of the first and second driving members. The brushless electric machine according to claim 6,
The control circuit includes 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. Brushless electric machine. A brushless electric machine according to any one of claims 1 to 7,
The brushless electric machine, wherein the control circuit includes a regenerative circuit that regenerates electric power from the electromagnetic coil. A brushless electric machine according to claim 1;
A driven member driven by the brushless electric machine;
A device comprising:   A moving body comprising the brushless electric machine according to claim 1.

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