JP5506407B2 - Control device for three-phase brushless motor - Google Patents

Description

The present invention relates to a control device for a three-phase brushless motor, and more particularly to a control device for a three-phase brushless motor that can make the most of the advantages of the 180-degree energization method.
The present invention also relates to a control device for a three-phase brushless motor that can maximize the advantages of the 180-degree energization method in assist control of an electrically assisted bicycle.

  As a control method of a three-phase brushless motor, a 120-degree energization method and a 180-degree energization drive method (sine wave drive) are generally used. The 120-degree energization method has the advantage that it is easy to control and many general-purpose ICs are on the market. However, the 120-degree energization method is easier to generate noise and vibration than the 180-degree energization method, and it is efficient. There is a problem that it is inferior to the 180-degree energization method. On the other hand, the 180-degree energization method is more efficient than the 120-degree energization method and has the advantages of excellent silence and vibration characteristics. However, the 180-degree energization method is weak against transient load fluctuations and becomes uncontrollable when misalignment occurs. There is a drawback that the control is more complicated than the 120-degree energization method.

In both the 120-degree energization method and the 180-degree energization method, control is performed by detecting the phase of the rotor by a sensor such as a Hall IC attached to the motor. In the 180-degree energization method, the magnetic pole position is predicted and controlled every 60 degrees. Therefore, if a positional deviation occurs due to a transient load fluctuation during motor rotation, the magnetic pole position cannot be predicted and the operation may have to be stopped. On the other hand, in the 120-degree energization method, phase current switching control is performed based on the rotor position detected by the sensor, and control is not performed by prediction, so even if a positional deviation occurs, it is based on the position information from the sensor. The operation can be continued. Further, in the 180-degree energization method, the torque margin is small and the position is likely to be shifted with respect to an instantaneous load fluctuation, so that the torque must be increased and it is difficult to reduce the size of the motor.
As described above, the 180-degree energization method and the 120-degree energization method have advantages and disadvantages, respectively. Therefore, for example, Patent Documents 1 and 2 have proposed control methods that combine the respective energization methods to take advantage of each advantage. .

  Patent Document 1 includes a 180-degree energization drive means 10 and a 120-degree energization drive means 11, and switches the 180-degree energization drive means 10 and the 120-degree energization drive means 11 as necessary to control the drive of the synchronous motor 1. A control device for an electric vehicle is described. In this control device, the magnetic pole position θenc is calculated based on the output pulse from the rotation pulse generator 9 and the 180-degree energization drive is performed based on the magnetic pole position θenc. However, when the rotation pulse generator 9 cannot be used. The magnetic pole position θv is calculated on the basis of the phase voltage V1, and 120-degree energization driving is performed. The control device described in Patent Document 1 switches from the 180-degree energization method to the 120-degree energization method based on the motor rotation speed. However, depending on the load state, the position shift may increase in the 180-degree energization drive, and control may become impossible. There is sex.

  Patent Document 2 includes an intermittent energization drive unit (120-degree energization drive unit) 8 and a 180-degree energization drive unit 9, which performs 180-degree energization drive in a steady state to prevent disturbance due to fluctuations in power supply voltage and load torque. When detected, a synchronous motor control device that executes intermittent energization drive (for example, 120-degree energization drive) is described. In this control device, for example, a DC power supply voltage, the number of rotations of the synchronous motor, a load torque generated in the synchronous motor, a motor current that changes accompanying these, and a phase difference between the drive voltage and the motor current are detected as disturbance signals. When the disturbance signal exceeds a threshold value, the 180-degree energization drive is switched to the intermittent energization drive. However, it is assumed that the drive system is switched before the occurrence of misalignment.Thus, when switching the drive system by comparing the disturbance signal with the threshold value, it is effective when the controlled object is slow, but the controlled object is When the speed is high, a position shift occurs while determining the presence or absence of disturbance, and control becomes impossible. Therefore, the control method of Patent Document 2 cannot avoid stopping the motor when a transient and sudden load change occurs. Moreover, since a phase difference between the drive voltage and the motor current is detected, a high-performance microcomputer is necessary, and it is difficult to reduce the cost.

Japanese Patent Laid-Open No. 10-341594 JP 2001-245487 A

The objective of this invention is providing the control apparatus of the three-phase brushless motor which can prevent the stop of the motor by a transient load fluctuation more reliably.
An object of the present invention is to provide a control device for a three-phase brushless motor that can take full advantage of the 180-degree energization method.

One aspect of the present invention relates to a control device for a three-phase brushless motor, and a three-phase bridge inverter circuit (15) for supplying a drive voltage to each phase (U, V, W) of the three-phase brushless motor (37); A PWM signal having a conduction angle of less than 180 degrees is applied to the transistors (UH, UL, VH, VL, WH, WL) of the inverter circuit (15) to drive the three-phase brushless motor by a complementary intermittent energization driving method. Complementary intermittent energization drive means (32). Complementary intermittent energization drive means (32) applies PWM signals having different duty ratios to the upper and lower transistors of each phase in two of the three phases to flow current through the two-phase coil and In one phase, PWM signals having the same duty ratio are applied to the upper and lower transistors in one phase, and a current is caused to flow through any of the upper and lower transistors by the energy accumulated in the one-phase coil. A current is passed through the corner to drive the three-phase brushless motor in complementary intermittent energization. The complementary intermittent energization drive method is, for example, a complementary 120-degree energization drive method.
For example, the control device controls the three-phase brushless motor by a complementary intermittent energization driving method in at least one of a startup operation state and a transient load state.
Here, the transient load state is an overload state in which the motor load increases rapidly, and means, for example, an overload state.
According to the control of the three-phase brushless motor by the complementary intermittent energization driving method excellent in handling transient loads, it is possible to reliably prevent the motor from being stopped due to transient load fluctuations. In other words, in the motor control by the 180-degree energization driving method, since the control is performed by predicting the destination, it is necessary to stop the motor when a positional deviation occurs due to a transient load fluctuation, but in the motor control by the complementary intermittent energization driving method, Since the control is performed only based on information from the sensor, it is possible to avoid a motor stop due to a transient load fluctuation. In addition, according to the complementary intermittent energization driving method, it is possible to operate a motor having excellent silence and vibration characteristics. Further, by preventing the motor from being stopped due to a transient load fluctuation by the complementary intermittent energization driving method, it is not necessary to excessively increase the torque for the purpose of preventing the displacement, and the motor and its driving device can be downsized. It is also possible.

In one aspect of the present invention, the three-phase brushless motor is controlled by a complementary intermittent energization driving method in at least one of a startup operation state and a transient load state of the three-phase brushless motor.
When the motor is controlled by the complementary intermittent energization driving method in the start-up operation state, it is possible to reliably avoid stopping the motor even when there is a transient load fluctuation at the time of motor start-up. In addition, after the motor is reliably started, for example, by performing normal operation by a 180-degree energization drive method, it is possible to perform motor control with excellent silence, vibration characteristics, and efficiency.
In addition, when controlling a motor by a complementary intermittent energization driving method in a transient load state, for example, the motor is started by a 180 degree energization driving method, and when there is a transient load change, a motor by a complementary intermittent energization driving method When the control is switched and the transient load state is released, the 180-degree energization drive system is restored. In addition, for example, the motor is controlled by the 180-degree energization drive method during normal operation after the motor is started, and when there is a transient load change, the motor is switched to the complementary intermittent energization method. Return to the energization drive system. In this case, it is possible to control the motor efficiently by avoiding the stop of the motor due to the transient load fluctuation, and it is possible to suppress the rotation unevenness and improve the vibration characteristic and the quietness. Further, the motor and its driving device can be reduced in size by preventing the motor from being stopped in the starting operation state or the transient load state by the complementary intermittent energization driving method.

In one aspect of the present invention, a 180-degree conduction drive means (33) that applies a PWM signal having a conduction angle of 180 degrees to the inverter circuit (15) and drives the three-phase brushless motor (37) by a 180-degree conduction drive system. ) And a complementary intermittent energization drive method in the start-up operation state of the three-phase brushless motor (37), and when the operation state of the three-phase brushless motor (37) becomes a normal operation state, the 180-degree energization drive method Drive system selection means (31) for selecting
In this case, the motor is reliably started by the complementary intermittent energization drive method, and when the motor is in a normal operation state, the motor is controlled by the 180-degree energization drive method, so that silence, vibration characteristics and efficiency are excellent. The motor can be operated.

In one aspect of the present invention, intermittent energization drive means (34) for applying a PWM signal having a conduction angle of less than 180 degrees to the inverter circuit (15) to drive the three-phase brushless motor (37) by an intermittent energization drive system. The drive method selection means (31) selects the intermittent energization drive method when a transient load state of the three-phase brushless motor (37) is detected. The intermittent energization driving method is, for example, a 120-degree energization driving method.
In this case, when a transient load condition is detected during normal operation of the three-phase brushless motor, the motor is prevented from stopping by controlling the motor with an intermittent energization drive system with excellent transient load compatibility. can do. Since the intermittent energization drive method is more efficient than the complementary intermittent energization drive method, even when a transient load state continues for a long time, the motor operation can be continued while suppressing a decrease in efficiency.

In one aspect of the present invention, the drive method selection means (31) selects the intermittent energization drive method after detecting the transient load state, and then detects the 180 degree energization drive method when the release of the transient load state is detected. Return to.
In this case, when the transient load state is canceled, the control is switched from the intermittent energization drive method to the 180 ° energization drive method, so that the 180 ° energization drive method excellent in quietness, vibration characteristics and efficiency is utilized to the maximum. can do.

  In one aspect of the present invention, the drive method selection means (31) is configured such that the rotational speed of the three-phase brushless motor (37) is equal to or higher than a predetermined value and the three-phase brushless motor (37) is rotated in the positive rotation direction. When the number of times is continuously detected a predetermined number of times or more, it is determined that the startup operation state has shifted to the normal operation state.

  In one aspect of the present invention, the driving method selection means (31) determines that the three-phase brushless motor (37) is in a transient load state when rotation in the reverse direction is detected. . In this case, when a pulse edge indicating reverse rotation of the motor is detected even once, it is determined that a transient load state exists, so the transient load state is detected quickly, and the intermittent energization drive method is changed from the 180-degree energization drive method. The motor can be reliably prevented from stopping.

  In one aspect of the present invention, the three-phase brushless motor (37) is used for assist control of an electrically assisted bicycle, and the drive method selection means (31) has a predetermined rotational speed of the three-phase brushless motor (37). When the number of rotations in the positive rotation direction of the three-phase brushless motor (37) is continuously detected a predetermined number of times or more and the pedaling force range of the electrically assisted bicycle is a predetermined value or less. It is determined that the transient load state has been released.

  In one aspect of the present invention, the three-phase brushless motor (37) is used for assist control of an electrically assisted bicycle, and the drive method selection means (31) has a predetermined rotational speed of the three-phase brushless motor (37). It is determined that the transient load state has been released when the vehicle speed of the electrically assisted bicycle is equal to or greater than a predetermined value.

  One aspect of the present invention is a control device for a three-phase brushless motor, which is a three-phase bridge inverter circuit (15) for supplying a drive voltage to each phase (U, V, W) of the three-phase brushless motor (37). And a PWM signal having a conduction angle of 120 degrees is applied to the transistors (UH, UL, VH, VL, WH, WL) of the inverter circuit (15), and the three-phase brushless motor is driven by a complementary 120-degree conduction drive system. Complementary 120 degree conduction drive means (32). The complementary 120-degree energization driving means (32) applies PWM signals having different duty ratios to the upper and lower transistors of each phase in two phases out of the three phases to flow current through the two-phase coils and In one phase, PWM signals having the same duty ratio are applied to the upper and lower transistors in one phase, and a current is caused to flow through either of the upper and lower transistors by the energy accumulated in the one-phase coil. A current is passed at an electrical angle to drive the three-phase brushless motor through a complementary 120-degree conduction.

  The control device for a three-phase brushless motor according to the present invention is not limited to the complementary 120-degree energization drive system, and can be applied to any complementary intermittent drive system that drives at a conduction angle of less than 180 degrees.

  The control device for a three-phase brushless motor according to the present invention can be applied to an electric assist unit of an electric assist bicycle.

FIG. 1 is a schematic view of an electrically assisted bicycle according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a control system of the electrically assisted bicycle shown in FIG. FIG. 3 is a side view of a one-way clutch used in the electrically assisted bicycle shown in FIG. 1 and incorporating a torque detection mechanism according to an embodiment of the present invention. FIG. 4 is a view showing the configuration of the one-way clutch piece and the spring bar used in the piece part, wherein (a) is a perspective view of the piece part with the spring bar attached, ) Is a perspective view of the piece part with the spring bar removed, and FIG. 5C is a side view of the spring bar. FIG. 5 is a diagram showing a fitting state of teeth and pieces of a one-way clutch (ratchet gear) in order to explain the principle of pedaling force detection of the electrically assisted bicycle shown in FIG. FIG. 6 is a view showing an example of rotation preventing means for preventing relative rotation of the piece portion with respect to the drive shaft. (A) is a ball spline, (b) is a spline key, and (c) is a schematic configuration of a key groove. FIG. FIG. 7 is a front view and a side view of a power transmission gear used in the resultant force mechanism according to the embodiment of the present invention. FIG. 8 is a current waveform diagram of each phase in the 180-degree energization driving method. FIG. 9 is a current waveform diagram of each phase in the 120-degree energization driving method. FIG. 10 is a diagram showing the duty ratio and current path of the PWM signal in the 120-degree energization drive method. FIG. 11 is a current waveform diagram of each phase in the complementary 120-degree conduction drive method. FIG. 12 is a diagram illustrating the duty ratio and current path of the PWM signal in the complementary 120-degree energization drive method. FIG. 13 is a flowchart showing a flow of control by the motor control device according to the embodiment of the present invention. FIG. 14 is a diagram for explaining control compatibility between the 120-degree conduction drive method and the complementary 120-degree conduction method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows an outline of the electrically assisted bicycle 1. As shown in the figure, the main skeleton portion of the electrically assisted bicycle 1 is composed of a body frame 3 made of metal pipe, as in a normal bicycle. The body frame 3 includes a front wheel 20 and a rear wheel 22. , Handle 16 and saddle 18 are attached in a known manner.

  A drive shaft 4 is rotatably supported at the lower center of the vehicle body frame 3, and pedals 8L and 8R are attached to left and right ends thereof via pedal cranks 6L and 6R, respectively. A sprocket 2 is coaxially attached to the drive shaft 4 via a one-way clutch (99 in FIG. 3 described later) for transmitting only rotation in the R direction corresponding to the forward direction of the vehicle body. An endless rotating chain 12 is stretched between the sprocket 2 and a rear wheel power mechanism 10 provided at the center of the rear wheel 22.

  An electric assist unit 11 that generates an auxiliary electric force is attached to the electric assist bicycle 1. The generated auxiliary electric force is transmitted to the drive wheel (rear wheel) 22 using a resultant force mechanism described later.

  An outline of the control system of the electric assist bicycle 1 housed in the electric assist unit 11 is shown in FIG. The control system of the electric assist bicycle 1 includes a microcomputer 14 that collectively controls electronic processing of the entire bicycle, an electric motor 37 capable of PWM control, and a DC voltage based on a control signal from the microcomputer 14. And an inverter circuit 15 that converts the voltage waveform into a predetermined voltage and supplies it to the motor 37. A battery 17 (external to the electric assist unit 11) for supplying power to the electric motor 37 is connected to the inverter circuit 15. Further, the electric assist unit 11 accommodates a reduction gear or the like for reducing the rotational speed of the motor.

  The electric motor 37 is, for example, a three-phase brushless motor. The electric motor 37 is provided with, for example, a plurality of Hall ICs 371 in order to detect the magnetic pole position (rotor phase), the motor rotation speed, and the like. The Hall IC 371 outputs a pulse signal corresponding to a magnetic field generated by a permanent magnet provided in the electric motor 37. For example, three Hall ICs 371 are provided at equal intervals around the rotation axis of the electric motor 37, but only one Hall IC 371 is shown in FIG. The microcomputer 14 detects the magnetic pole position, the motor rotation speed, the number of motor rotations, and the motor rotation direction based on the pulse signal from the Hall IC 371.

  The inverter circuit 15 is a three-phase bridge inverter, and is a circuit in which transistors UH, UL, VH, VL, WH, and WU, which are six semiconductor switching elements, are connected in a three-phase bridge shape. These transistors are driven by a PWM signal supplied from the microcomputer 14, convert a DC voltage supplied from the battery 17 to generate a drive voltage, and supply it to each phase of the electric motor 37.

  The microcomputer 14 also receives a magnetic field pulse signal for detecting the crank angle formed by the pedal crank 6R (6L) with respect to the vehicle body frame 3 from a rotation angle sensor (described later), and the one-way clutch. Magnetic field signals 1, 2, and 3 for calculating a pedaling force are input from a Hall IC 162 (described later) for detecting deformation. Means for generating these input signals will be described later. A signal for designating an electric assist mode (for example, normal mode, turbo mode, eco mode, etc.) may also be input. The microcomputer 14 (a driving method selection unit 31 described later) calculates a traveling speed (vehicle speed), a crank angle, and a pedaling force from these input signals, and determines an assist ratio (an assisting force / a pedaling force) based on a predetermined algorithm. Perform electronic processing. Next, in order to instruct the electric motor 37 to generate an assist force corresponding to the determined assist ratio, the microcomputer 14 sequentially outputs PWM commands corresponding to the assist force. Details of motor control by the microcomputer 14 according to the present embodiment will be described later.

  Hereinafter, a pedal force detection mechanism, a resultant force mechanism, and a crank angle and vehicle speed detection mechanism of an electrically assisted bicycle according to an embodiment of the present invention will be described.

(Treading force detection mechanism)
A pedaling force detection mechanism that outputs magnetic field signals 1, 2, and 3 input to the microcomputer 14 will be described with reference to FIGS. The pedaling force detection mechanism detects a magnetic field that changes due to the deformation of the one-way clutch 99 according to the pedaling force.

  As shown in FIG. 3, the one-way clutch 99 includes a piece part 100 and a tooth part 112.

  As shown in FIG. 4A, the piece portion 100 has a substantially disk shape in which a piece portion bore 106 for receiving the drive shaft 4 is formed in the central portion, and is equiangular along its circumferential direction. Three rigid ratchet pieces 102 are arranged on the second engagement surface 110 side facing the tooth portion 112. Since the piece part 100 accommodates each ratchet piece 102, as shown in FIG.4 (b), the three recessed parts 170 are formed along the circumferential direction. Thus, the ratchet piece 102 rotates in a state where the rotation shaft portion is accommodated in the concave portion 170, and the ratchet piece 102 changes the angle with respect to the second engagement surface 110 in accordance with this rotation.

  Referring to FIG. 4B again, the piece portion 100 is formed with linear grooves 171 that can accommodate the spring bars 104 adjacent to the respective concave portions 170, and both end portions of the three linear grooves 171. Extends to the outer peripheral edge of the piece 100. As shown in FIG. 4C, the spring bar 104 has one end A bent substantially vertically and the other end B bent in a U shape. When the spring bar 104 is mounted in the straight groove 171 of the piece part 100, as shown in FIG. 4 (b), the U-shaped B part ties the piece part 100 while sliding the spring bar 104 in the straight groove. The spring bar 104 can be easily attached to the piece part 100 simply by being clamped. However, if this is left, the spring bar 104 may fall off due to the pulling force from the B part. Therefore, the A part bent vertically is engaged with the side wall of the piece part to prevent the spring bar from falling off. .

  When the spring bar 104 is attached to the straight groove 171 of the piece part 100, the length direction of the ratchet piece 102 makes a predetermined angle with respect to the second engagement surface 110 when no external force is applied ( It rises in the direction of equilibrium 160) in FIG. As shown in FIG. 5, when the ratchet piece 102 is biased from the equilibrium direction 160 in the ascending direction a or the descending direction b, the spring bar 104 is slightly elastic to the ratchet piece 102 so as to return the bias to the equilibrium direction 160. Effect.

  Four first anti-rotation grooves 108 extending in the axial direction 5 are formed in the inner wall of the piece bore 106. Four second anti-rotation grooves 140 extending in the axial direction 5 so as to face the first anti-rotation groove 108 are also formed on the outer wall portion of the drive shaft 4 that is in sliding contact with the inner wall of the piece bore 106. ing. As shown in FIG. 6A, the first antirotation groove 108 and the second antirotation groove 140 facing the first antirotation groove form a cylindrical groove extending along the axial direction. Inside, a large number of steel balls 150 are accommodated so as to fill them. Thereby, the piece part 100 can move along the axial direction with the minimum friction coefficient, and the relative rotation with respect to the drive shaft 4 is prevented. This is a kind of ball spline, but other types of ball splines, such as an endless rotating ball spline, can be applied as such a slidable rotation preventing means.

  Further, as a method of attaching the piece portion 100 to the drive shaft 4, it is possible to use means other than the ball spline of FIG. For example, as shown in FIG. 6B, a protrusion 140a extending in the axial direction is provided on the drive shaft 4, and a third anti-rotation groove 108a that accommodates the protrusion 140a is formed in the piece 100. A key spline type is also applicable as a rotation prevention means. In FIG. 6B, the protrusion 140a may be provided on the piece 100 side and the third rotation preventing groove 108a may be provided on the drive shaft 4 side. Further, as shown in FIG. 6C, a fourth rotation prevention groove 108b extending in the axial direction and a fifth rotation prevention groove 140b facing the groove are provided in the piece portion 100 and the drive shaft 4, respectively. A so-called key groove type in which the key plate is accommodated in a rectangular parallelepiped groove formed by the groove is also applicable as the rotation preventing means.

  As shown in FIG. 3, a disc spring 137 is interposed between the piece portion 100 and a support disk 151 fixed to the drive shaft 4. Both end portions of the disc spring 137 are in contact with the back surface of the piece portion 100 and the support disk 151, respectively. Accordingly, the disc spring 137 is opposed to the sliding of the piece portion 100 inward in the axial direction by an elastic force.

  On the other hand, as shown in FIG. 7, the tooth portion 112 is formed on a first engagement surface 121 that is a surface of the power transmission gear 200. The tooth part 112 has a plurality of ratchet pieces 114 for engaging with the ratchet piece 102. As shown in FIG. 5, the ratchet teeth 114 are formed periodically in a staggered manner along the circumferential direction of the tooth portion, and have a steeper inclination 118 with respect to the first engagement surface 121 and a gentler shape. And a slope 116. The tooth portion 112 is driven in a state where the first engagement surface 121 faces the second engagement surface 110 of the piece portion 100 and the ratchet piece 102 and the ratchet teeth 114 are engaged (FIG. 5). The shaft 4 is pivotally supported so as to be slidable. That is, the drive shaft 4 is operatively connected to the tooth portion 112 only through the engagement portion between the ratchet piece 102 and the ratchet teeth 114.

  As shown in FIG. 3, the power transmission gear 200 including the tooth portion 112 is fixed coaxially with the sprocket 2 using a fixing pin 206, and a pedal shaft is attached to the tip of the drive shaft 4. Thus, a one-way clutch (ratchet gear) 99 for connecting the drive shaft 4 and the sprocket 2 so as to transmit only the rotation by the pedal depression force in the vehicle body forward direction to the sprocket 2 is completed.

  Further, a permanent magnet 161 formed in a ring shape is attached to the piece portion 100 of the ratchet gear 99 concentrically with the drive shaft 4 and the piece portion 100. The ring-shaped permanent magnet 161 is preferably configured so that one surface of the ring is N-pole and the opposite surface is S-pole, and the ring axial direction of the permanent magnet 161 and the axial direction of the ratchet gear 99 are Arranged to align.

  Further, a plurality (three in this embodiment) of Hall ICs 162 for detecting the magnetic field are respectively arranged at three predetermined positions in a plane perpendicular to the axis of the drive shaft 4. Preferably, the three predetermined positions at which the Hall ICs are arranged are positions approximately equidistant in the radial direction and approximately equiangular in the circumferential direction around the axis. Further, the predetermined position where the Hall IC 162 is disposed corresponds to a fixed position of the vehicle body frame 3 in the vicinity of the ring-shaped permanent magnet 161. These Hall ICs 162 are connected to the microcomputer 14 (FIG. 2). As described above, the magnetic field signals (magnetic field detection signals) 1, 2, and 3 output from the three Hall ICs 162 are input to the microcomputer 14 (FIG. 2).

  As an alternative embodiment, a ring member 163 made of a magnetic material such as iron can be used instead of the ring-shaped permanent magnet 161. In this case, the magnet 164 is fixed at a position close to the Hall IC 162 on the piece unit 100. The material of the ring member 163 can also be made of any material that can change the magnetic field of the magnet 164, for example, a diamagnetic material.

  When the rider applies a pedaling force to the pedals 8R and 8L (FIG. 1) and rotates the drive shaft 4 in the vehicle body forward direction, the rotational force is pivotally supported with respect to the drive shaft 4 so that it cannot rotate and can slide. Is transmitted to the frame unit 100. At this time, as shown in FIG. 5, the ratchet piece 102 is given a force Fd corresponding to the pedal depression force from the piece portion 100, so that its tip portion comes into contact with the steep slope 118 of the ratchet teeth of the tooth portion 112. Try to transmit this force to the ratchet teeth. Since the ratchet teeth 112 are connected to the sprocket 2, the tip of the ratchet piece 102 receives a force Fp due to a load for driving from a steeper slope 118. The ratchet piece 102 to which opposite forces Fp and Fd are applied from both ends thereof rotates in the direction a and rises. At this time, the piece part 100 moves inward in the axial direction by the rising of the ratchet piece 102 and pushes the disc spring 137 interposed between the piece part 100 and the support disk 151. The disc spring 137 counteracts this and applies an elastic force Fr to the piece portion 100. This force Fr and the force reflecting the pedal depression force that moves the piece part 100 in the axial direction are balanced in a short time. Thus, the axial position of the piece 100 is a physical quantity that reflects the pedal effort.

  In the case of the embodiment using the ring-shaped permanent magnet 161, the magnetic field strength detected by the Hall IC 162 differs depending on the position of the piece portion 100 in the axial direction. That is, when the pedal depression force increases, the piece portion 100 slides inward in the axial direction, and the permanent magnet 161 approaches the Hall IC 162, so that the magnetic field strength detected by the Hall IC 162 increases. On the contrary, when the pedal depression force decreases, the piece portion 100 slides outward in the axial direction, and the permanent magnet 161 moves away from the Hall IC 162, so that the magnetic field strength detected by the Hall IC 162 decreases.

  The treading force range detection unit 40 (see FIG. 2) of the microcomputer 14 calculates the average magnetic field strength by averaging (including simple addition) the magnetic field signals 1, 2, and 3 detected by the three Hall ICs 162, and calculates the average The pedaling force range is obtained based on the magnetic field strength. In the present embodiment, the value of the magnetic field strength is divided into a plurality of ranges (stepping force ranges) in advance, and the assist ratio is set according to the pedaling force range. That is, the assist ratio is set based on the pedaling force range to which the magnetic field strength belongs.

  As described above, since the magnetic fields in the axial direction at a plurality of locations are averaged, not only can the SN ratio be improved, but also the pedal can be more accurately corrected by offsetting the variation in the magnetic field strength caused by the shake of the piece 100. The pedaling force T (the pedaling force range) can be obtained.

  In the case of an alternative embodiment using a magnetic or diamagnetic ring member 163, the magnetic field distribution of the magnet 164 changes depending on the influence of the magnetic body or diamagnetic body depending on the axial position of the ring member 163. To do. Therefore, also in the alternative embodiment, the pedal depression force T (the depression force range) can be obtained as described above based on the detected magnetic field strength.

  In the above description, the pedal force is detected by detecting the axial displacement of the piece 100 (one-way clutch 99) by the Hall IC 162. However, a strain gauge is disposed on the disc spring 137 to detect the strain of the disc spring 137. Thus, the axial displacement of the piece portion 100 (one-way clutch 99), and thus the pedaling force (the pedaling force range) may be detected. In this case, the value of the strain gauge is divided into a plurality of ranges (stepping force ranges) in advance, and the assist ratio is set according to the pedaling force range.

(Force mechanism)
FIG. 3 shows the power transmission gear 200 fixed coaxially to the sprocket 2 using the fixing pin 206 as described above. As shown in FIG. 7, the power transmission gear 200 has a plurality of teeth 204 formed on the outer periphery.

  As shown in FIG. 3, the teeth 204 of the power transmission gear 200 are engaged with a gear 220 provided at the tip of the assist force output shaft 222 of the electric assist unit 11. Therefore, the assist force output from the electric assist unit 11 is transmitted to the power transmission gear 200 via the shaft 222 and the gear 220, and the driving wheel (rear wheel) is transmitted from the power transmission gear 200 via the sprocket 2 and the chain 12. 22 is transmitted. Thus, the resultant force of the pedaling force and the assist force is achieved. Since the number of teeth 204 of the power transmission gear 200 is larger than the number of teeth of the gear 220, the power transmission gear 200 also functions as a reduction gear. The assist force output shaft 222 is driven by the above-described electric motor 37 (FIG. 2).

(Crank angle and vehicle speed detection mechanism)
A crank angle detection mechanism of the electrically assisted bicycle 1 will be described with reference to FIGS. 3 and 7.
As shown in FIG. 7, twelve permanent magnets 202 are equally divided into a circumference 12 on one plate surface side of the power transmission gear 200. These permanent magnets 202 emit one magnetic pole (N pole or S pole) to the surface of the plate surface, the other magnetic pole is directed to the opposite side of the surface, and the direction connecting both magnetic poles is the axis of the drive shaft 4. It is arranged to align in the direction. It is preferable that all the magnetic poles appearing on the surface of the plate surface are the same, but the magnetic poles of adjacent magnets 202 may be arranged alternately.

  Referring to FIG. 3, the Hall IC 210 is disposed at a position fixed to the vehicle body frame 3 adjacent to the plate surface of the power transmission gear 200 where the permanent magnet 202 is disposed. The radial distance of the Hall IC 210 from the drive shaft 4 is set to be substantially the same as the radial distance of the permanent magnet 202 from the drive shaft 4. The permanent magnet 202 and the Hall IC 210 constitute a crank rotation angle sensor. The power transmission gear 200 rotates with the rotation of the pedal, while the Hall IC 210 is stationary with respect to the vehicle body, so that the magnetic field of the permanent magnet 202 crosses the detection range of the Hall IC 210 one after another by the pedal crank rotation. Accordingly, the Hall IC 210 outputs a detection signal with the number of pulses corresponding to the pedal crank rotation speed. This magnetic field pulse signal is input to the vehicle speed detector 41 of the microcomputer 14 (FIG. 2).

  Since the power transmission gear 200 rotates together with the pedal crank and the sprocket 2, the rotational speed of the power transmission gear 200 reflects the vehicle speed and the crank angular speed. Thus, the vehicle speed detector 41 can calculate the vehicle speed and the crank angle from the number of magnetic field pulse signals counted per unit time.

(Motor control device)
Next, a control device for the electric motor 37 that generates the auxiliary electric force of the electric assist unit 11 will be described with reference to FIG. 2 and FIGS. 8 to 14.

  As described above, the motor control device according to FIG. 2 includes the inverter circuit 15 that supplies a driving voltage to the three-phase brushless electric motor 37, the microcomputer 14, and three Hall ICs 371 (only one is shown in FIG. 2). It has. The three Hall ICs 371 are arranged at equal intervals of 120 degrees in the electric motor 37, and the pulse signals Hu, Hv, Hw shown in the upper part of FIGS. Output.

  Hereinafter, for convenience of explanation, the transistors of the inverter circuit 15 connected to the U, V, and W phases of the electric motor 37 are referred to as a U phase transistor, a V phase transistor, and a W phase transistor, respectively. Among transistors, a transistor on the high potential side may be referred to as an upper transistor, and a transistor on the low potential side may be referred to as a lower transistor.

  In the microcomputer 14, the transient load state detection unit 36 receives the pulse signals Hu, Hv, Hw output from the three Hall ICs 371, and the pulse signals Hu, Hv, Hw indicate that the motor rotation is in the positive direction (CW direction). Whether or not it matches the pulse signal pattern in this case is constantly monitored. The transient load state detection unit 36 is electrically operated when the received pulse signals Hu, Hv, Hw are different from the forward pulse signal pattern, that is, when the pulse edge indicating the motor rotation in the reverse direction (CCW direction) is detected. It is determined that the motor 37 is in the hunting operation state (transient load operation state), and a transient load state detection signal is output.

Table 1 is a truth table of the pulse signals Hu, Hv, Hw output from the Hall IC 371.
As shown in Table 1, assuming that the magnetic pole position is currently in the range of 0-60 degrees and the pulse signal is detected by the Hall IC 371 as Hu, Hv, Hw = 0, 1, 0, the following 60 The signal pattern that should come in the range of −120 degrees is Hu, Hv, Hw = 0, 1, 1. Therefore, if the microcomputer 14 receives a signal pattern other than Hu, Hv, Hw = 0, 1, 1 after Hu, Hv, Hw = 0, 1, 0, the microcomputer 14 immediately reverses the motor. Judged as rotation or misalignment.

  The motor rotation speed detector 38 counts the number of switching of the pulse signal pattern (number of pulse edges) output from the Hall IC 371 and calculates the rotation speed (motor rotation speed rpm) of the electric motor 37 per minute. To do.

  The motor rotation number detection unit 39 monitors the change in the pattern of the pulse signals output from the three Hall ICs 371 and detects whether the motor rotation is in the forward direction or the reverse direction (detects a pulse edge in the forward direction or the reverse direction). At the same time, the number of rotations of the motor in the forward direction and the reverse direction is calculated by counting the number of switching of the pulse signal pattern.

  As described above, the treading force range detection unit 40 (see FIG. 2) calculates the average magnetic field strength by averaging (including simple addition) the magnetic field signals 1, 2, and 3 detected by the three Hall ICs 162, By referring to the look-up table, the pedaling force range is obtained from the average magnetic field strength. The assist ratio by the assist unit 11 is determined in consideration of the pedaling force range, but the pedaling force range in which the average value of the magnetic field signals 1, 2, and 3 corresponding to the pedaling force T is less than a predetermined value (the pedaling force range = 0). Represents no load as an internal parameter, and is set so that the assist force is not generated (assist ratio 0) in this pedaling force range.

  The vehicle speed detection unit 41 receives a detection signal (magnetic pulse signal) of the number of pulses corresponding to the pedal crank rotation speed output from the Hall IC 210, and calculates the vehicle speed, the crank angle, and the number of magnetic field pulse signals per unit time. Is calculated.

  The energization drive method selection unit 31 is based on the motor rotation speed, the number of motor rotations, the motor rotation direction, the treading force range, the vehicle speed, and the transient load state detection signal, and the 180 ° energization drive method, the 120 ° energization drive method, and the complementary 120. One of the current drive methods is selected, and a selection signal for the current drive method is output. Specifically, the energization drive method selection unit 31 outputs a complementary 120-degree energization drive selection signal when the electric motor 37 is started (starting operation state), and 180 when the electric motor 37 is normally operated (normal operation state). When the electric motor 37 is in a transient load operation state (hunting operation state), a 120 degree energization drive signal is output.

  The detection of each operation state is performed as follows as an example. It is determined that the start-up operation state satisfies both the conditions of “motor rotation speed of 50 rpm or more” and “detecting the number of positive motor rotations 60 times continuously”, and the normal operation state is satisfied when both conditions are satisfied. It is determined that

  Further, after detecting the normal operation state, if “the number of reverse rotations of the motor is detected even once”, it is determined that the state is the hunting operation state (transient load operation state).

  Further, when the three conditions of “the motor rotation speed is 126 rpm or more”, “the motor rotation number in the positive direction is continuously detected 240 times”, and “the pedal force range is 0 (internal parameter indicates no load)” are satisfied, It is determined that the normal operation state has been reached from the hunting operation state (transient load operation state). Here, “the pedaling force range is 0” is one condition, but “the pedaling force range is a predetermined value or less” may be used. The detection of the release of the hunting operation state (transient load operation state) is detected when the two conditions “motor rotational speed is 126 rpm or more” and “vehicle speed (internal speed) is 6 km / h or more” are satisfied. It may be determined that the normal operation state is reached from (transient load operation state).

  The 180-degree energization drive unit 33 calculates the magnetic pole position based on the pulse signals received from the three Hall ICs 371 installed in the electric motor 37, and based on the calculated magnetic pole position, the drive current as shown in FIG. The electric motor 37 is energized and driven 180 degrees with a waveform. Specifically, when the 180-degree energization drive unit 33 receives the 180-degree energization drive selection signal from the energization drive method selection unit 31, the assist ratio (assist value) is determined based on a predetermined algorithm from the vehicle speed, the crank angle, and the pedaling force range. Electronic processing to determine (force / pedal force). Further, the 180-degree energization drive unit 33 energizes the electric motor 37 by predicting the magnetic pole position based on the detection value of the Hall IC 371 in order to drive the electric motor 37 by 180 degrees so as to generate an assist force corresponding to the determined assist ratio. The timing is set, and the duty ratio of the PWM signal is set according to the assist ratio.

  The 120-degree energization drive unit 34 calculates the magnetic pole position based on the pulse signals received from the three Hall ICs 371 installed in the electric motor 37, and based on the calculated magnetic pole position, the drive current as shown in FIG. The electric motor 37 is energized and driven by 120 degrees with a waveform. Specifically, when the 120-degree energization drive unit 34 receives the 120-degree energization drive selection signal from the energization drive method selection unit 31, the assist ratio (assist value) is determined based on a predetermined algorithm from the vehicle speed, the crank angle, and the pedaling force range. Electronic processing to determine (force / pedal force). The 120-degree energization drive unit 34 sets the energization timing based on the magnetic pole position detected by the Hall IC 371 in order to drive the electric motor 37 by 120 degrees so as to generate an assist force corresponding to the determined assist ratio. At the same time, the duty ratio of the PWM signal is set based on the assist ratio.

  The complementary 120-degree energization drive unit 32 calculates the magnetic pole position based on the pulse signals received from the three Hall ICs 371 installed in the electric motor 37, and drives as shown in FIG. 11 based on the calculated magnetic pole position. The electric motor 37 is energized and driven by a complementary 120 degree with a current waveform. Specifically, when the complementary 120-degree energization drive unit 32 receives the complementary 120-degree energization drive selection signal from the energization drive method selection unit 31, the assist ratio is determined based on a predetermined algorithm from the vehicle speed, the crank angle, and the pedaling force range. Electronic processing for determining (assist force / stepping force) is performed. In addition, the complementary 120-degree energization drive unit 32 drives the electric motor 37 in a complementary 120-degree energization manner so as to generate an assist force corresponding to the determined assist ratio, so that the energization timing is determined based on the magnetic pole position detected by the Hall IC 371. In addition to setting, the duty ratio of the PWM signal is set.

  The PWM generator 35 is configured to set the transistors (UH, UL, VH) of the inverter circuit 15 based on the energization timing and the duty ratio set by the 180-degree energization drive 33, the 120-degree energization drive 34, and the complementary 120-degree energization drive 32. , VL, WH, WL) is generated and output for each transistor.

  The inverter circuit 15 switches each transistor according to a PWM signal output from the microcomputer 14 for 180-degree conduction drive, 120-degree conduction drive, or complementary 120-degree conduction drive, and applies a drive voltage ( Drive current).

Hereinafter, the complementary 120-degree conduction drive method will be described in comparison with the 120-degree conduction drive method.
[120 degree energization drive system]
FIG. 9 is a diagram showing the current waveform (vertical axis) of each phase of the motor with respect to the energized electrical angle (horizontal axis) in the 120-degree driving method. FIG. 10 is a diagram for explaining a duty ratio of a PWM signal applied to each transistor and a path of a current flowing in each phase of the motor in the 120-degree energization driving method. In these figures, <1> is an electrical angle of 0 to 60 degrees, <2> is an electrical angle of 60 to 120 degrees, <3> is an electrical angle of 120 to 180 degrees, <4> is an electrical angle of 180 to 240 degrees, <5> indicates an electrical angle of 240 to 300 degrees, and <6> indicates an electrical angle of 300 to 360 degrees.

  In FIG. 10, in section <1>, for example, a PWM signal with a duty ratio of 25% is applied to the upper transistor UH and the lower transistor VL of the V phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors. And closed. At this time, the current output from the battery 17 flows into the U-phase coil of the electric motor 37 through the U-phase upper transistor UH, flows out from the V-phase coil, passes through the V-phase lower transistor VL, and passes through the battery 17. Return to. At this time, no current flows through the W-phase coil.

  In the interval <2>, a PWM signal with a duty ratio of 25% is applied to the upper transistor UH of the U phase and the lower transistor WL of the W phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors and closed. At this time, the current output from the battery 17 flows into the U-phase coil of the electric motor 37 through the U-phase upper transistor UH, flows out of the W-phase coil, passes through the W-phase lower transistor WL, and passes through the battery 17. Return to. At this time, no current flows through the V-phase coil.

  In the section <3>, a PWM signal with a duty ratio of 25% is applied to the upper transistor VH of the V phase and the lower transistor WL of the W phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors and closed. At this time, the current output from the battery 17 flows into the V-phase coil of the electric motor 37 through the V-phase upper transistor VH, and current flows from the W-phase coil through the W-phase lower transistor WL. Return to battery 17. At this time, no current flows through the U-phase coil.

  In the section <4>, a PWM signal with a duty ratio of 25% is applied to the upper transistor VH of the V phase and the lower transistor UL of the U phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors and closed. At this time, the current output from the battery 17 flows into the V-phase coil of the electric motor 37 through the V-phase upper transistor VH, flows out from the U-phase coil, passes through the U-phase lower transistor UL, and passes through the battery 17. Return to. At this time, no current flows through the W-phase coil.

  In the section <5>, a PWM signal with a duty ratio of 25% is applied to the upper transistor WH of the W phase and the lower transistor UL of the U phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors and closed. At this time, the current output from the battery 17 flows into the W-phase coil of the electric motor 37 through the W-phase upper transistor WH, and current flows from the U-phase coil through the U-phase lower transistor UL. Return to battery 17. At this time, no current flows through the V-phase coil.

  In a section <6>, a PWM signal with a duty ratio of 25% is applied to the upper transistor WH of the W phase and the lower transistor VL of the V phase, and a PWM signal with a duty ratio of 0% is applied to the other transistors and closed. At this time, the current output from the battery 17 flows into the W-phase coil of the electric motor 37 through the W-phase upper transistor WH, and the current flows out from the V-phase coil through the V-phase lower transistor VL. Return to battery 17. At this time, no current flows through the U-phase coil.

  In the above description, a case where a PWM signal having a duty ratio of 25% is applied to the transistor to be conducted is described as an example, but the value of the duty ratio is changed according to the assist ratio.

  As can be seen from FIGS. 9 and 10, in the 120-degree conduction drive method, in each phase of U, V, and W, a section in which current does not flow in an electrical angle range of 60 degrees between the conduction sections of an electrical angle of 120 degrees ( Non-energized section).

[Complementary 120-degree conduction drive]
As shown in FIG. 14, the complementary 120-degree energization drive method is an energization drive method that theoretically controls compatibility of the duty ratio of the PWM signal of the 120-degree energization drive method. As shown in FIG. 14, in the 120-degree energization driving method, a PWM signal having a duty ratio of 0% is applied to both the upper and lower transistors UH and UL that are not selected as current paths. By applying a PWM signal of 50% each, the current flowing through the motor is made zero. Using this principle, the transistor that is turned on is determined by the higher one of the upper and lower transistors UH, UL. For example, as shown in the middle stage of FIG. 14, if the duty ratio of the upper transistor UH is 75% and the duty ratio of the lower transistor UL is 25%, current flows from the upper transistor UH to the motor. Conversely, if the duty ratio of the upper transistor UH is 25% and the duty ratio of the lower transistor UL is 75%, current flows from the motor into the lower transistor UH. In the complementary 120-degree energization drive method, using this principle, in the two-phase upper and lower transistors selected as the current path, the duty ratio of one of the upper and lower transistors is made larger than the duty ratio of the other transistor, In the phase not selected, the upper and lower transistors have the same duty ratio.

  FIG. 11 is a diagram showing a current waveform (vertical axis) of each phase of the motor with respect to the energized electrical angle (horizontal axis) in the complementary 120-degree driving method. FIG. 12 is a diagram for explaining a duty ratio of a PWM signal applied to each transistor and a path of a current flowing in each phase of the motor in the complementary 120-degree energization driving method. In these drawings, sections <1> to <6> indicate sections of energized electrical angles similar to those in FIGS. 9 and 10. Here, a specific duty ratio will be described as an example, but the value of the duty ratio is changed according to the assist ratio.

  In the complementary 120-degree conduction drive method, as shown in section <1> of FIG. 12, in the two-phase U and V phases (corresponding to section <1> in FIG. 10) selected as the current path in the 120-degree conduction drive system, By applying a PWM signal with a duty ratio of 75% to the transistors UH and VL, and applying a PWM signal with a duty ratio of 25% to the transistors UL and VH, the current is passed through the transistors UH and VL as in the 120-degree conduction drive method. Flowing (solid arrow). In addition, a PWM signal with a duty ratio of 50% is applied to both the W-phase upper and lower transistors WH and WL that are not selected as current paths so that the current flowing in the W-phase is theoretically zero. However, in the complementary 120-degree energization drive method, in the W phase that is not selected as the current path, the energy accumulated in the W phase coil of the motor is discharged at the timing when the transistor WL is turned on (broken arrow). This is because the current flows into the W-phase coil of the electric motor 37 in the preceding sections <5> to <6> until immediately before the section <1> (solid arrow), and the inverter circuit 15 side in the W-phase coil is in the middle. This is because energy is accumulated so that the potential is higher than the sex point. With the energy, the lower transistor WL passes through the lower transistor WL from the W-phase coil at the timing when the lower transistor WL is turned on in the section <1>. Current flows out to the potential side (dashed arrow).

  The same applies to the sections <2> to <6> other than the section <1>. In the section <2>, a current flows in the U phase and the W phase as in the section <2> of FIG. On the other hand, PWM signals having the same duty ratio (50%) are applied to the V-phase upper and lower transistors VH and VL, but the motor V in the preceding sections <6> and <1> immediately before section <2>. A current flows out of the phase coil, and energy is stored in the V-phase coil in a state where the neutral point side is at a higher potential than the inverter circuit 15 side. Therefore, when a PWM signal with a duty ratio of 50% is applied to the V-phase upper and lower transistors VH and VL in the section <2>, the upper transistor VH is turned on at the timing when a pulse is applied to the upper transistor VH, and the battery 17 Current flows into the V-phase coil from the high potential side of the first through the upper transistor VH (broken line arrow).

  In the section <3>, a current flows in the V phase and the W phase as in the section <3> of FIG. A PWM signal having the same duty ratio (50%) is applied to the U-phase upper and lower transistors UH and UL, but the U-phase coil of the motor in the preceding sections <1> and <2> until immediately before section <3>. In the U-phase coil, energy is stored in a state where the inverter circuit 15 side is at a higher potential than the neutral point side. Accordingly, when a PWM signal with a duty ratio of 50% is applied to the U-phase upper and lower transistors UH and UL in the section <3>, the lower transistor UL is turned on at the timing when a pulse is applied to the lower transistor UL, and the U-phase A current flows from the coil to the low potential side of the battery 17 via the lower transistor UL (broken arrow).

  In the section <4>, a current flows in the U phase and the V phase as in the section <4> of FIG. PWM signals having the same duty ratio (50%) are applied to the W-phase upper and lower transistors WH and WL, but in the preceding sections <2> and <3> until immediately before section <4>, the W-phase coil of the motor As a result, current flows out, and energy is stored in the W-phase coil in a state where the neutral point side is at a higher potential than the inverter circuit 15 side. Therefore, in the section <4>, when a PWM signal with a duty ratio of 50% is applied to the W-phase upper and lower transistors WH and WL, the upper transistor WH is turned on at the timing when a pulse is applied to the upper transistor WH, and the battery 17 Current flows into the W-phase coil from the higher potential side of the first through the upper transistor WH (broken arrow).

  In the section <5>, a current flows in the U phase and the W phase as in the section <5> in FIG. A PWM signal having the same duty ratio (50%) is applied to the V-phase upper and lower transistors VH and VL. The V-phase coil of the motor in the preceding sections <3> and <4> until immediately before section <5>. In the V phase coil, energy is stored in a state where the inverter circuit 15 side is at a higher potential than the neutral point. Therefore, when a PWM signal with a duty ratio of 50% is applied to the V-phase upper and lower transistors VH and VL in the section <5>, the lower transistor VL is turned on at the timing when the pulse is applied to the lower transistor VL, and the V-phase Current flows from the coil to the low potential side of the battery 17 via the lower transistor VL (broken line arrow).

  In the section <6>, current flows in the V phase and the W phase as in the section <6> of FIG. A PWM signal having the same duty ratio (50%) is applied to the U-phase upper and lower transistors UH and UL, but the U-phase coil of the motor in the preceding sections <4> and <5> until immediately before section <6>. A current flows out from the coil, and energy is stored in the U-phase coil in a state where the neutral point side is at a higher potential than the inverter circuit 15 side. Therefore, when a PWM signal with a duty ratio of 50% is applied to the U-phase upper and lower transistors UH and UL in the section <6>, the upper transistor UL is turned on at the timing when a pulse is applied to the upper transistor UL, and the battery 17 Current flows into the U-phase coil from the high potential side of the first through the upper transistor UL (broken arrow).

  As described above, in the complementary 120-degree energization drive, current flows in all the sections <1> to <6> in any of the U, V, and W phases, and there is no non-conduction section in any phase. For this reason, as shown in FIG. 11, the electric current of each phase changes continuously through an electrical angle of 360 degrees, and the electric vibration at the time of phase switching that can occur in the 120-degree conduction drive system can be suppressed. .

[Control flow]
Hereinafter, an example of motor control using the motor control apparatus according to the present embodiment will be described with reference to the flowchart of FIG.

  In step S11, the electric motor 37 is activated by complementary 120-degree energization drive.

  In step S12, it is determined whether or not the rotation speed of the electric motor 37 is 50 rpm or more and the number of rotations of the electric motor 37 in the positive direction (CW direction) is continuously detected 60 times. If any of the conditions is not satisfied, the process proceeds to step S11, and the startup operation by the complementary 120-degree energization drive is continued.

  When both conditions of step S12 are satisfy | filled, it transfers to step S13 and switches to the motor control by a 180 degree | times energization drive system.

  In step S14, it is determined whether or not a transient load fluctuation is detected. Specifically, it is determined whether or not “motor rotation in the reverse direction (CCW direction) has been detected even once”. If the motor rotation in the reverse direction is not detected, the process proceeds to step S13 and 180 ° energization is performed. Continue motor control by drive system.

  On the other hand, when the motor rotation in the reverse direction is detected in step S14, the process proceeds to step S15 to switch to motor control by the 120-degree energization drive method.

  In step S16, it is determined whether or not the transient load state is released. Specifically, when the three conditions of “motor rotation speed is 126 rpm or more”, “positive motor rotation is continuously detected 240 times” and “stepping force range is 0” are satisfied, the overload state is released. To detect. The release of the overload state may be detected when the two conditions “the motor rotation speed is 126 rpm or more” and “the vehicle speed (internal speed) is 6 km / h or more” are satisfied.

  If the release of the transient load state is not detected in step S16, the process proceeds to step S15, and the motor control by the 120-degree energization drive method is continued.

  On the other hand, when the release of the transient load state is detected in step S16, the process proceeds to step S13 to return to the motor control by the 180-degree energization drive method.

[Comparison of energization drive systems]
Table 2 shows the characteristics of each energization drive method of the 180 degree energization drive method, the 120 degree energization drive method, and the complementary 120 degree energization drive method. In the table, the double circle notation indicates that the characteristics are particularly good among the three energization drive systems, the single circle notation indicates that the characteristics are good, and the triangle notation is slightly inferior to the performance. The cross indicates that the performance is inferior.

  As shown in Table 2, the 180 degree energization driving method has particularly good silence, vibration characteristics, and efficiency. On the other hand, the 180-degree energization driving method is weak in adaptability to transient loads because it is controlled by predicting the tip, and there is a possibility that control becomes impossible if a position shift occurs due to a transient load. Further, the 180-degree energization drive method is more complicated to control than the 120-degree energization drive method.

  The 120-degree energization drive method is controlled based only on the magnetic pole position detected by the Hall IC of the motor, and is not predicted and controlled, so that the transient load response characteristic is particularly excellent. For this reason, it is possible to continue the control even during operation in an overload state due to a sudden load fluctuation, and it is possible to avoid stopping the motor. Moreover, the control is simple and the efficiency is good. However, the vibration characteristics are slightly inferior, and there are disadvantages that the quietness is inferior.

  The complementary 120-degree energization drive method is controlled based only on the magnetic pole position detected by the Hall IC of the motor, and is not predicted and controlled, so that the transient load response characteristic is particularly excellent. Excellent transient load response characteristics. For this reason, it is possible to continue the control even during operation in an overload state due to a sudden load fluctuation, and it is possible to avoid stopping the motor. In addition, silence and vibration characteristics are particularly good. On the other hand, the control is complicated and the efficiency is the worst among the three systems.

  In the above-described embodiment, during the motor start-up operation that may cause a transient load condition and that requires good silence and vibration characteristics, the motor start-up operation is performed by controlling the motor by the complementary 120-degree conduction drive method. Even when a transient load fluctuation occurs during the operation, the operation is continued while reliably avoiding the stop of the motor, thereby enabling a start-up operation with less noise and vibration.

  Also, during normal operation when the motor rotation speed and number of rotations have reached a predetermined value, the motor control is switched to the 180-degree energization drive system to enable comfortable operation with less noise and vibration, and to improve efficiency. This makes it possible to reduce power consumption.

  Also, if there is a transient load fluctuation during normal operation, the motor control can be switched to the 120-degree energization drive system to prevent the motor from being stopped and to continue the operation while suppressing the decrease in efficiency. Yes.

  In addition, when the transient load state is canceled after switching to the 120-degree conduction drive system, the operation with excellent silence, vibration characteristics and efficiency is utilized to the maximum by returning to the 180-degree conduction drive system. Is possible.

  As described above, according to the present embodiment, during the start-up operation of the motor, the motor is surely avoided from stopping while suppressing noise and vibration by the complementary 120-degree energization drive method. The degree-of-drive drive system makes it possible to maximize the use of efficient operation with less noise and vibration, and in the event of transient load fluctuations, the 120-degree conduction drive system suppresses the decrease in efficiency while maintaining the efficiency of the motor. Stops can be avoided reliably.

[Other embodiments]
In the above embodiment, when a transient load state is detected after shifting to the normal operation, control is performed to switch to the 120-degree energization drive method, but if the efficiency reduction is allowable, the normal operation is performed. When a transient load state is detected after the transition, it may be switched to the complementary 120-degree conduction drive method. In this case, driving with less noise and vibration is possible during transient load driving, and driving of the electrically assisted bicycle can be made more comfortable.

  In the above embodiment, the motor is started by the complementary 120-degree energization drive method. However, if noise and vibration can be allowed, the motor start-up operation may be performed by the 120-degree energization drive method. In this case, the efficiency at the start-up operation of the motor can be improved.

  Also, instead of the motor start control that continues the complementary 120-degree energization drive method (or 120-degree energization drive method) until the motor enters the normal operation state, the motor is started by the 180-degree energization drive method, and the transient load state It is also possible to switch to the complementary 120-degree energization drive method (or 120-degree energization drive method) and detect the release of the transient load state to return to the 180-degree energization drive method.

  In the above embodiment, the 120-degree energization driving method and the complementary 120-degree energization driving method have been described as examples. However, the present invention is not limited to 180 degrees and other intermittent operations that intermittently energize at a conduction angle other than 120 degrees. The present invention can be applied to an energization driving method and a complementary intermittent energization method.

14: Microcomputer 15: Inverter circuit 17: Battery 37: Motor 371: Hall IC

Claims (10)

A control device for a three-phase brushless motor,
A three-phase bridge inverter circuit (15) for supplying a driving voltage to each phase (U, V, W) of the three-phase brushless motor (37);
A PWM signal having a conduction angle of less than 180 degrees is applied to the transistors (UH, UL, VH, VL, WH, WL) of the inverter circuit (15) to drive the three-phase brushless motor by a complementary intermittent energization driving method. Complementary intermittent energization drive means (32) for applying PWM signals having different duty ratios to the upper and lower transistors of each phase in two out of the three phases to pass a current through the two-phase coil, and 3 In one of the phases, a PWM signal with a duty ratio of 50% is applied to both the upper and lower transistors, and a current is caused to flow through either of the upper and lower transistors by the energy accumulated in the one-phase coil. A complementary intermittent energization drive means (32) for supplying a current at all electrical angles and driving the three-phase brushless motor with complementary intermittent energization;
A control device for a three-phase brushless motor, comprising: In the control apparatus of the three-phase brushless motor according to claim 1,
A control device for a three-phase brushless motor, wherein the three-phase brushless motor is controlled by a complementary intermittent energization driving method in at least one of a startup operation state and a transient load state of the three-phase brushless motor. In the control apparatus of the three-phase brushless motor according to claim 2,
180 degree conduction drive means (33) for applying a PWM signal having a conduction angle of 180 degrees to the inverter circuit (15) and driving the three-phase brushless motor (37) by a 180 degree conduction drive system;
When the three-phase brushless motor (37) is in the starting operation state, the complementary intermittent energization driving method is selected, and when the three-phase brushless motor (37) is in the normal operation state, the 180-degree energization driving method is selected. Drive system selection means (31);
A control device for a three-phase brushless motor, further comprising: In the control device of the three-phase brushless motor according to claim 3,
An intermittent energization drive means (34) for applying a PWM signal having a conduction angle of less than 180 degrees to the inverter circuit (15) and driving the three-phase brushless motor (37) in an intermittent energization drive system;
The three-phase brushless motor control device, wherein the driving method selection means (31) selects an intermittent energization driving method when a transient load state of the three-phase brushless motor (37) is detected. In the control device of the three-phase brushless motor according to claim 4,
The drive system selection means (31) is characterized in that after the transient load state is detected and the intermittent energization drive system is selected, when the release of the transient load state is detected, the drive system selection means (31) returns to the 180-degree energization drive system. A control device for a three-phase brushless motor. In the control device of the three-phase brushless motor according to claim 3,
The drive method selection means (31) has a rotational speed of the three-phase brushless motor (37) equal to or greater than a predetermined value, and the number of rotations of the three-phase brushless motor (37) in the positive rotation direction is continuously a predetermined number of times. A control device for a three-phase brushless motor, characterized in that, when detected as described above, it is determined that the startup operation state has shifted to the normal operation state. In the control device of the three-phase brushless motor according to claim 4,
The drive system selection means (31) determines that the three-phase brushless motor (37) is in a transient load state when rotation in the reverse direction of the three-phase brushless motor (37) is detected. apparatus. In the control device of the three-phase brushless motor according to claim 5,
The three-phase brushless motor (37) is used for assist control of an electrically assisted bicycle,
The drive method selection means (31) has a rotational speed of the three-phase brushless motor (37) equal to or greater than a predetermined value, and the number of rotations of the three-phase brushless motor (37) in the positive rotation direction is continuously a predetermined number of times. A control device for a three-phase brushless motor, characterized in that it is determined that the transient load state has been released when the pedaling force range of the electrically assisted bicycle is below a predetermined value. In the control device of the three-phase brushless motor according to claim 5,
The three-phase brushless motor (37) is used for assist control of an electrically assisted bicycle,
The drive system selection means (31) cancels the transient load state when the rotational speed of the three-phase brushless motor (37) exceeds a predetermined value and the vehicle speed of the electric assist bicycle exceeds a predetermined value. A control device for a three-phase brushless motor, characterized in that it has been determined.   An electric assist unit for an electric assist bicycle, comprising the control device for a three-phase brushless motor according to any one of claims 1 to 9.