JP4643061B2 - Drive control device for brushless DC motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control device for a brushless DC motor employed in a battery-assisted bicycle or the like, and more particularly, to an improvement in a motor drive control method that can suppress pedal kickback and pedal vibration.
[0002]
[Prior art]
For example, in the drive control of a brushless DC motor in a battery-assisted bicycle, the angular position of the rotor is detected at each switching point of the magnetic pole sensor signal of each phase of U, V, and W, and between the switching points (for example, an interval of 60 degrees electrical angle) In general, the angle correction for estimating the rotor angle is performed based on the motor rotation speed to obtain the rotor recognition angle. Based on the rotor recognition angle thus determined, feedback control is performed so that the excitation current to each excitation coil becomes an auxiliary current command value corresponding to the pedal effort.
[0003]
[Problems to be solved by the invention]
However, in the above-mentioned battery-assisted bicycle (1) when the pedal is strongly depressed with the brake applied, (2) the motor may reverse in a special case such as when the high pedal force starts. In some cases, the rotor angle recognition value may deviate from the actual angle.
[0004]
When the rotor angle recognition value deviates as described above, in the case (1), vibration (pedal kickback) is felt from the pedal, and in the case (2), fine pedal vibration (grinding feeling). ) Is felt.
[0005]
The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a drive control device for a brushless DC motor that can prevent or reduce the pedal kickback and pedal vibration.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, the angular position of the rotor is obtained for each switching point of the magnetic pole sensor signal, and the recognized angle of the rotor is determined by performing angle correction based on the motor rotation state between the obtained angular positions. In the drive control device for a brushless DC motor that controls the exciting current to the exciting coil based on the determined recognition angle, the rotor is rotated forward / reversely based on the switching state of the magnetic pole sensor signal. If it is determined that the rotation is reversed, the angle position at the time of detection of the reverse rotation is fixedly held without performing the angle correction.
[0007]
According to a second aspect of the present invention, in the same brushless DC motor drive control apparatus as in the first aspect, when the forward / reverse rotation of the rotor is determined based on the switching state of the magnetic pole sensor signal, and the reverse rotation is determined. It is characterized in that fixing and holding the excitation current value, the excitation current value of the reverse rotation detection.
[0008]
A third aspect of the invention is characterized in that, in the first or second aspect, it is determined that the reverse rotation has occurred when the magnetic pole sensor signal is switched in the reverse direction to the order of forward rotation.
[0009]
According to a fourth aspect of the present invention, when the magnetic pole sensor signal is switched a plurality of times in the normal rotation direction after determining that the reverse rotation has occurred in the third aspect, the angular position of the rotor corresponds to the magnetic pole sensor signal. The angle correction is resumed and the angle correction is restarted.
[0010]
[Effects of the invention]
According to the first aspect of the present invention, when the rotor is reversed, the angular position at the time of reverse rotation is fixedly held without performing the angle correction between the angular positions obtained from the magnetic pole sensor signal. , It is possible to suppress the rotor recognition angle from deviating from the actual angle, so that it is possible to suppress the excitation coil from being excited in the reverse direction. For example, vibration from the pedal when the pedal is strongly pressed while applying the brake (pedal kick Back) can be reduced.
[0011]
According to the second aspect of the present invention, when it is determined that the rotor is reversely rotated, the excitation current value is fixed at the time of reverse rotation detection. The excitation current value does not increase, and therefore, pedal vibration (crimping feeling) caused by an increase in the motor assisting force accompanying an increase in the pedaling force can be reduced. Further, it is possible to reduce an impact when the pawl clutch is engaged when the high pedaling force starts.
[0012]
According to the invention of claim 3, since it is determined that the reverse rotation has occurred when the magnetic pole sensor signal is switched in the reverse direction to the forward rotation order, the reverse rotation of the rotor is performed by a simple method. It can be detected.
[0013]
According to the fourth aspect of the present invention, when the magnetic pole sensor signal is switched in the forward rotation direction a plurality of times after the reverse rotation occurs, the rotor recognition angle is returned to a value corresponding to the magnetic pole sensor signal. Therefore, it is possible to suppress the pedal kickback and the harsh feeling that are likely to occur when the magnetic pole sensor signal reciprocates a certain switching point.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 7 are diagrams for explaining an embodiment of the present invention. FIG. 1 is a schematic side view of a battery-assisted bicycle equipped with the control device of the present embodiment. FIG. 2 is a schematic cross-sectional side view of a drive motor. 3 is a schematic sectional front view of the drive motor, FIG. 4 is a motor drive circuit diagram, FIG. 5 is a characteristic diagram for explaining the recognition operation of the angular position of the rotor, FIG. 6 is a motor reverse rotation processing block diagram, FIG. Is a motor reverse rotation processing flow.
[0015]
In FIG. 1, reference numeral 1 denotes a battery-assisted bicycle, and a body frame 2 of the body frame 2 stands up from a head pipe 3, a down tube 4 extending obliquely downward and rearward from the head pipe 3, and a rear end of the down tube 4. A pair of left and right chain stays 6 extending substantially horizontally rearward from the rear end of the down tube 4, a rear end portion of the chain stays 6, and an upper end portion of the seat tube 5. Are provided with a pair of left and right seat stays 7 and a horizontal tube 8 extending horizontally from the head pipe 3.
[0016]
A front fork 9 is supported on the head pipe 3 so as to be rotatable left and right. A front wheel 10 is pivotally supported at the lower end of the front fork 9, and a steering handle 11 is fixed to the upper end. A saddle 12 is mounted on the upper end of the seat tube 5. Further, a rear wheel 13 is pivotally supported at the rear end of the chain stay 6.
[0017]
A pedal unit 14 is disposed at the center lower end of the vehicle body frame 2.
The pedal unit 14 rotates and drives the crankshaft 15c via the crank arm 15b by the pedaling force applied by the driver to the pedal 15a, and the gear ratio according to the gear stage of the transmission mechanism incorporating the rotation of the crankshaft 15c. The gear is shifted and output, and the output is transmitted to the hub 18 of the rear wheel 13 by the chain 16.
[0018]
A pedaling force sensor 17 for continuously detecting the pedaling force applied to the pedal 15a is disposed in the pedal unit 14. The pedal force sensor 17 generates a pedal force voltage corresponding to the magnitude of the pedal force.
[0019]
A drive motor 20 is disposed in the hub 18 of the rear wheel 13. The drive motor 20 is a brushless three-phase DC motor, and generates auxiliary power corresponding to a motor auxiliary current (excitation current) value supplied from the battery 19. The auxiliary power and the pedaling force transmitted through the rear chain 16 after passing through the speed change mechanism are combined to drive the hub 18 and thus the rear wheel 13.
[0020]
A controller 21 is disposed in the pedal unit 14. The controller 21 is for controlling the operation of the drive motor 20, and is a motor auxiliary current (excitation current) command value for generating motor auxiliary power corresponding to the pedal depression force detected by the pedal force sensor 17. And the feedback control is performed so that the auxiliary current value actually supplied to the drive motor 20 matches the motor auxiliary current command value. As a result, motor assist power is generated by multiplying the pedal depression force by a predetermined assist ratio (usually 1.0), and the motor assist power is supplied to the rear wheel 13 together with the pedal effort.
[0021]
As shown in FIGS. 2 and 3, the drive motor 20 is rotatably housed and held in a stator 23 fitted and fixed to the inner surface of a motor case 22 and in the motor case 22 via bearings 24a and 24b. And a rotor 24. One end of the rotating shaft 25 of the rotor 24 protrudes to the outside of the motor case 22, and this protruding end serves as a motor output shaft.
[0022]
The stator 23 is obtained by winding exciting coils 31a to 31c around nine field leg portions 23a protruding radially inward at equal angular intervals. The exciting coils 31a to 31c wound around the nine field leg portions 23a are divided into U, V, and W phase exciting coils. A rotating magnetic field is formed. The rotor 24 has a cylindrical yoke 26 fitted and fixed to the rotary shaft 25, and eight permanent magnets 27 are fixed to the outer peripheral surface of the yoke 26 at equal angular intervals.
[0023]
Further, three Hall elements 29 a, 29 b, and 29 c that function as a magnetic sensor for detecting the rotational angle position of the rotor 24 are opposed to the one end surface of the permanent magnet 27 in the longitudinal direction of the rotary shaft 25. And arranged at intervals of 120 °. The Hall elements 29a to 29c are fixedly supported at fixed positions by a holding plate 30 fixed to the motor case 22.
[0024]
The detection outputs of the Hall elements 29a to 29c are input to the controller 21. The controller 21 obtains the recognition angle of the rotor 24 as will be described in detail below, and the above-described excitation coils of each phase are applied to the excitation coils according to the recognition angle. The motor auxiliary current (excitation current) corresponding to the pedal depression force is supplied by feedback control.
[0025]
The U, V, and W phase sensor outputs detected by the Hall elements 29a, 29b, and 29c in accordance with the rotation of the rotor 24 of the drive motor 20 are shown in FIG. It changes to high / low every 180 degrees and forms a rectangular wave whose phases are shifted by 120 °. Therefore, the magnetic pole sensor signal indicating the combined state of the three rectangular waves is switched every 60 electrical degrees.
[0026]
When the rotor 24 is rotating forward, the actual angle of the rotor 24 is 0 degree and 60 degrees every time the magnetic pole sensor signal is switched (every edge) as shown in FIG. , 120 degrees, and the electrical angle also changes to 0 degrees, 60 degrees, and 120 degrees. Since the magnetic pole sensor signal changes to 101,001,011 according to the electrical angle, the recognition angle of the rotor 24 determined based on the magnetic pole sensor signal is 0 degree as shown in FIG. , 60 degrees and 120 degrees, which coincide with the actual angle. In addition, the above-mentioned recognition angle coincides with the actual angle more accurately by angle correction estimated according to the motor rotation speed between 0 degrees and 60 degrees and 120 degrees.
[0027]
Then, according to the recognition angle of the rotor 24 obtained in this way, as shown in FIG. 4, the energization control FET 32 is on / off controlled by the control signal from the controller 21, and the U, V, W phase excitation coils are controlled. Is excited. Reference numeral 33 denotes a feedback current detection sensor for detecting a current value actually flowing through the exciting coil.
[0028]
Here, when the magnetic pole sensor signal changes as previously planned, such as 101,001,011,..., It is determined that the rotor 24 is rotating forward as described above. The recognition value of the rotation angle of the rotor 24 coincides with the actual 0 degrees, 60 degrees, 120 degrees, etc., and the rotor angle is between the detected angles of 0 degrees to 60 degrees to 120 degrees. The position is estimated by calculating back from the motor rotation speed.
[0029]
On the other hand, when the rotor 24 is reversed to 60 degrees when the actual angle changes from 120 degrees to 180 degrees, for example, the magnetic pole sensor signal does not change from 011 to 010 after switching to 011. Will be changed to 001. Thus, when the magnetic pole sensor signal changes in the direction opposite to the predetermined direction, it is determined that the magnetic field sensor signal has been reversed, and the angle recognition value of the rotor 24 is fixed to the angle (120 degrees) at the time of the reverse rotation.
[0030]
When reverse rotation occurs in this way, the angle recognition value of the rotor 24 is fixed to the angle at the time of reverse rotation, and the excitation current to the excitation coil is controlled according to the fixed angle. When the pedal is strongly depressed while the brake is applied, the excitation coil can be prevented from being excited in the reverse direction, and vibration from the pedal (pedal kickback) can be reduced.
[0031]
Incidentally, in the conventional apparatus, as shown by the broken line in FIG. 5C, the angle is estimated even when the reverse rotation occurs, and the difference between the angle recognition value and the actual angle becomes large, and the excitation to the excitation coil is increased. There was a problem that the current control was actually not suitable and the kickback felt strong.
[0032]
In addition, since it is determined that the magnetic pole sensor signal is reversed when it changes in the direction opposite to the predetermined direction, the occurrence of reverse rotation can be detected with a simple and low-cost configuration.
[0033]
The angle recognition value of the rotor 24 is returned to the normal value corresponding to the magnetic pole sensor signal when the magnetic pole sensor signal is switched a plurality of times (in this embodiment, twice) in the forward rotation direction. That is, for example, when the magnetic pole sensor signal is switched from 001 to 011 and further switched to 010, the angle recognition value is changed from 120 degrees to 180 degrees.
[0034]
Since the angle recognition value is returned to the normal value when the magnetic pole sensor signal is switched twice in the forward direction in this way, the magnetic sensor signal reciprocates in the forward direction and the reverse direction. Even in this case, the kickback can be reliably suppressed.
[0035]
The control of the angle recognition value of the rotor 24 will be further described based on the flowchart of FIG. First, it is determined whether or not the magnetic pole sensor signal has changed (step S1). If it has changed, it is determined whether or not reverse rotation has occurred when the sensor signal has been changed last time. It is determined whether or not reverse rotation has occurred this time based on the order of changes in sensor signals (steps S2 and S3). When it is determined that the rotation is not reverse, it is recognized that the rotation is normal (step S4), the angle of the rotor 24 is recognized based on the magnetic pole sensor signal (step S5), and the estimated angle is added to the recognition angle. The rotor angle is set, and the above-described excitation coil (motor coil) is excited according to the rotor angle (steps S6 to S7).
[0036]
On the other hand, if it is determined in step S2 that the rotation has been reversed last time, if it is determined that the rotation has been reversed in step S3, and if it is determined in step S10 that will be described later that the rotation is being reversed, the rotation of the rotor 24 is recognized. The angular position is fixed at the previous recognition angle (steps S8 and S9), and the motor coil is excited according to the fixed recognition angle (step S7).
[0037]
If there is no change in the magnetic pole sensor signal in step S1, it is determined whether or not reverse rotation is being performed. If not, angle estimation is performed (steps S10 and S11), and the estimated angle is added to the recognition angle. The rotor angle is set, and the above-described excitation coil (motor coil) is excited according to the rotor angle (steps S6 to S7).
[0038]
In the above embodiment, when the reverse rotation occurs, the recognition angle of the rotor 24 is fixed to the angle before the reverse rotation occurs. In addition to this, the motor auxiliary current command value is generated when the reverse rotation occurs. You may make it fix to the electric current value of time.
[0039]
In this case, since the motor auxiliary current (excitation current) value does not increase even if the pedal depression force is increased, the excitation coil is not strongly excited in the reverse direction. This can reduce the pedal vibration (crimping feeling). Further, it is possible to reduce an impact when the one-way clutch is engaged when starting.
[Brief description of the drawings]
FIG. 1 is a side view of a battery-assisted bicycle equipped with a drive motor control device according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional side view of the drive motor.
FIG. 3 is a schematic sectional front view of the drive motor.
FIG. 4 is a drive control block diagram of the drive motor.
FIG. 5 is a characteristic diagram showing sensor output and rotor angle for explaining motor reverse rotation processing of the control device.
FIG. 6 is a block diagram of motor reverse rotation processing of the control device.
FIG. 7 is a motor reverse rotation process flow of the control device.
[Explanation of symbols]
20 Brushless DC motor 24 Rotor 29a-29c Magnetic pole sensor 31a-31c Excitation coil

Claims (4)

 The angle position of the rotor is obtained for each switching point of the magnetic pole sensor signal, and the recognized angle of the rotor is determined by performing angle correction based on the motor rotation state between the obtained angle positions, and the determined recognition In the brushless DC motor drive control device that controls the excitation current to the excitation coil based on the angle, the forward / reverse rotation of the rotor is determined based on the switching state of the magnetic pole sensor signal, and the reverse rotation is determined. In such a case, a drive control device for a brushless DC motor, wherein the angle position at the time of reverse rotation detection is fixedly held without performing the angle correction. An angle position of the rotor is obtained for each switching point of the magnetic pole sensor signal, and an angle correction based on the motor rotation state is performed between the obtained angle positions to determine the recognition angle of the rotor, and the determined recognition In a brushless DC motor drive control device that controls the excitation current to the excitation coil based on the angle,
Based on the switching state of the magnetic pole sensor signal, the forward / reverse rotation of the rotor is determined,
A drive control device for a brushless DC motor, characterized in that when it is determined that the motor is reversely rotated, the exciting current value is fixedly held at the exciting current value at the time of detecting the reverse rotation.  3. The drive control device for a brushless DC motor according to claim 1, wherein the reverse rotation is determined to occur when the magnetic pole sensor signal is switched in the reverse direction to the order of forward rotation.  4. When the magnetic pole sensor signal is switched in the forward rotation direction a plurality of times after determining that the reverse rotation has occurred in claim 3, the angle position of the rotor is returned to a value corresponding to the magnetic pole sensor signal and the angle correction is performed. The brushless DC motor drive control device.

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