JP2003009577A - Drive controller for brushless dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive controller for a brushless DC motor wherein pedal kickback and pedal vibration are prevented or reduced. SOLUTION: The drive controller for a brushless DC motor 20 is constituted so that the angular position of a rotor 24 is determined at each point of switching of the signals of magnetic pole sensors 29a to 29c; based on the state of motor revolution, the angle is corrected between the determined angular positions, and the recognized angle of the rotor 24 is thereby determined; and based on the determined recognized angle, exciting currents to exciting coils 31a to 31c are controlled. Based on the state of switching of the magnetic pole sensors, it is judged whether the rotor 24 is rotating normally or reversely. If the rotor is judged as reversely rotating, the above correction of angle is not performed, and the angular position when the reverse rotation was detected is fixed and retained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a brushless DC motor used in an electric assisted bicycle or the like, and more particularly to an improvement in a motor drive control method capable of suppressing pedal kickback and pedal vibration. .

[0002]

2. Description of the Related Art For example, in drive control of a brushless DC motor in an electric assisted bicycle, the angular position of a rotor is detected at each switching point of magnetic pole sensor signals of U, V, and W phases, and between the switching points (for example, electric power). In a section of an angle of 60 degrees, it is general to perform an angle correction to estimate the angle of the rotor based on the motor rotation speed, and thereby obtain the recognized angle of the rotor. Based on the rotor recognition angle thus obtained, feedback control is performed so that the exciting current to each exciting coil becomes the auxiliary current command value according to the pedal effort.

[0003]

However, in the above-mentioned electric assisted bicycle, in a special case such as (1) when the pedal is strongly depressed with the brake applied, (2) especially when the high pedaling force is started, the motor is May reverse, and in such a case, the recognized value of the rotor angle may deviate from the actual angle.

When the rotor angle recognition value is deviated as described above, vibration (pedal kickback) is felt from the pedal in the case of (1), and fine pedal vibration is detected in the case of (2). There is a problem that (a feeling of stiffness) is felt.

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 capable of preventing or reducing the pedal kickback and the pedal vibration.

[0006]

According to a first aspect of the present invention, the angular position of the rotor is obtained for each switching point of the magnetic pole sensor signals, and the angle correction is performed between the obtained angular positions based on the motor rotation state. In the drive control device of the brushless DC motor, the recognition angle of the rotor is determined by, and the excitation current to the excitation coil is controlled based on the determined recognition angle, based on the switching state of the magnetic pole sensor signal. It is characterized in that the rotor is normally or reversely rotated, and when it is judged that the rotor is rotated in reverse, the angle position is fixed and held when the reverse rotation is detected without performing the angle correction.

According to a second aspect of the present invention, in the same drive control device for the brushless DC motor as the first aspect, it is determined whether the rotor is rotating normally or reversely on the basis of the switching state of the magnetic pole sensor signal, and it is determined that the rotor is rotating in reverse. In this case, the exciting current value at the time of detecting reverse rotation is held fixed.

According to a third aspect of the present invention, in the first or second aspect, it is determined that the reverse rotation has occurred when the magnetic pole sensor signal is switched in a direction opposite to the order of the normal rotation. .

According to a fourth aspect of the present invention, in the third aspect, when the magnetic pole sensor signal is switched in the forward rotation direction a plurality of times after it is determined that the reverse rotation has occurred, the angular position of the rotor is set to the magnetic pole sensor signal. It is characterized in that the angle correction is restarted while returning to the value corresponding to.

[0010]

According to the first aspect of the present invention, when the rotor is rotated in the reverse direction, the angular position at the time of reverse rotation detection is fixed without performing the angle correction between the angular positions obtained from the magnetic pole sensor signal. Since it is held, it is possible to suppress the recognition angle of the rotor from deviating from the actual angle, and thus to suppress exciting the exciting coil in the reverse direction, for example, when pedaling hard when pedaling while applying the brake. Vibration (pedal kickback) can be reduced.

According to the second aspect of the present invention, when it is determined that the rotor has rotated in the reverse direction, the exciting current value is fixed to the value when the reverse rotation is detected, so that the pedaling force increases, for example, when the high pedaling force starts. The excitation current value does not increase even when the pedal is operated, and therefore the pedal vibration (rigid feeling) that occurs due to the increase of the motor assist force with the increase of the pedal effort.
Can be reduced. Further, it is possible to reduce the impact when the pawl clutch engages at the time of starting the high pedaling force.

According to the third aspect of the present invention, it is determined that the reverse rotation has occurred when the magnetic pole sensor signal is switched in the reverse direction of the forward rotation order. Reversal of can be detected.

According to the invention of claim 4, when the magnetic pole sensor signal is switched a plurality of times in the forward rotation direction after the reverse rotation occurs, the recognition angle of the rotor is returned to a value corresponding to the magnetic pole sensor signal. Therefore, it is possible to suppress the above-described pedal kickback and ruggedness that are likely to occur when the magnetic pole sensor signal reciprocates at a certain switching point.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 7 are views for explaining an embodiment of the present invention, FIG. 1 is a schematic side view of an electric assisted bicycle equipped with a control device of the present embodiment, and FIG. 2 is a schematic sectional side view of a drive motor. 3, FIG. 3 is a schematic cross-sectional front view of the drive motor, FIG. 4 is a motor drive circuit diagram, FIG. 5 is a characteristic diagram for explaining the operation of recognizing the angular position of the rotor, FIG. 6 is a motor reverse rotation processing block diagram, and FIG. Is a motor reverse rotation processing flow.

In FIG. 1, reference numeral 1 is an electric assisted bicycle, and a body frame 2 of the electric assisted bicycle has a head pipe 3, a down tube 4 extending obliquely downward and rearward of the vehicle body from the head pipe 3, and a rear end of the down tube 4. A seat tube 5 extending upright, a pair of left and right chain stays 6 extending substantially horizontally rearward from the rear end of the down tube 4, rear end portions of both chain stays 6 and the seat tube 5. It is provided with a pair of left and right seat stays 7 connecting the upper end portion and a horizontal tube 8 extending horizontally from the head pipe 3.

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 on the lower end of the front fork 9, and a steering handle 11 is fixed on the upper end. A saddle 12 is attached to 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.

A pedal unit 14 is arranged at the lower center of the body frame 2. The pedal unit 14 rotationally drives the crank shaft 15c through the crank arm 15b by the pedaling force applied to the pedal 15a by the driver, and the rotation speed of the crank shaft 15c is changed according to the gear stage of the speed change mechanism. The speed is changed and output, and the output is transmitted to the hub 18 of the rear wheel 13 by the chain 16.

Further, a pedal force sensor 17 for continuously detecting the pedal force applied to the pedal 15a is provided in the pedal unit 14. The pedal effort sensor 17 generates a pedal effort voltage according to the magnitude of the pedal effort.

A drive motor 20 is arranged in the hub 18 of the rear wheel 13. The drive motor 20 is a brushless three-phase DC motor, and generates auxiliary power according to the motor auxiliary current (excitation current) value supplied from the battery 19. The auxiliary power and the pedaling force transmitted via the chain 16 after passing through the speed change mechanism are combined to produce the hub 1
Therefore, the rear wheels 13 are driven.

A controller 21 is arranged 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 effort detected by the pedal force sensor 17. And feedback control is performed so that the auxiliary current value actually supplied to the drive motor 20 matches the motor auxiliary current command value. Thus, a motor assist power generated by multiplying the pedal effort by a predetermined assist ratio (normally 1.0) is generated, and the motor assist power is supplied to the rear wheel 13 together with the pedal effort.

As shown in FIGS. 2 and 3, the drive motor 20 is rotatable via a stator 23 fitted and fixed to the inner surface of the motor case 22 and bearings 24a and 24b in the motor case 22. The rotor 24 accommodated and held. One end of the rotary shaft 25 of the rotor 24 projects outside the motor case 22, and this projected end serves as a motor output shaft.

The stator 23 has nine field leg portions 23a projecting inward in the radial direction at equal angular intervals and an exciting coil 31a.
~ 31c is wound. The above 9 field legs 2
The exciting coils 31a to 31c wound around 3a are U, V,
It is divided into W-phase exciting coils, and a rotating magnetic field is formed at the center of the stator 23 by passing a current through the exciting coils of each phase. In the rotor 24, a cylindrical yoke 26 is fitted and fixed to the rotating shaft 25, and eight permanent magnets 27 are fixed to the outer peripheral surface of the yoke 26 at equal angular intervals.

Further, three Hall elements 29a, 29b, 29c functioning as magnetic sensors for detecting the rotational angular position of the rotor 24 are opposed to one end surface of the permanent magnet 27 in the longitudinal direction of the rotary shaft 25. And 120 °
It is arranged at intervals. In addition, this Hall element 29a-
29c is fixedly supported at a fixed position by a holding plate 30 fixed to the motor case 22.

The detection outputs of the Hall elements 29a to 29c are input to the controller 21, and the controller 2
Reference numeral 1 determines the recognition angle of the rotor 24 as described in detail below, and supplies the motor auxiliary current (excitation current) corresponding to the pedaling force described above to the exciting coils of each phase by feedback control according to the recognized angle. .

The sensor outputs of the U, V and W phases detected by the Hall elements 29a, 29b and 29c according to the rotation of the rotor 24 of the drive motor 20 are shown in FIG.
As shown in (a), it switches to high / low for every 180 electrical degrees, and forms a rectangular wave in which the phase of each phase is shifted by 120 °. Therefore, the magnetic pole sensor signal indicating the combined state of these three rectangular waves is switched every 60 electrical degrees.

When the rotor 24 is rotating normally,
The actual angle of the rotor 24 is, as shown in FIG.
0 at each switching (every edge) of the magnetic pole sensor signal
The electrical angle also changes to 0, 60, and 120 degrees. Then, according to the electrical angle, the magnetic pole sensor signal is 101,000.
As shown in FIG. 5C, the recognition angle of the rotor 24, which is determined based on the magnetic pole sensor signal, changes to 0 degrees, 60 degrees, and 120 degrees. Matches The recognition angle is 0 to 60 degrees to 1.
Between 20 degrees ... Accurately matches the actual angle due to the angle correction estimated according to the motor rotation speed.

Then, the rotor 24 thus obtained
As shown in FIG. 4, the energization control FET 32 is turned on / off by a control signal from the controller 21 according to the recognition angle of, and the U, V, and W-phase exciting coils are excited. Reference numeral 33 is a feedback current detection sensor that detects the value of the current that actually flows in the exciting coil.

Here, the magnetic pole sensor signal is 101,0.
In the case of a change such as 01, 011 ... As scheduled, the rotor 24 is determined to be rotating in the normal direction, and the recognition value of the rotation angle of the rotor 24 is determined as described above. Coincides with actual 0 degrees, 60 degrees, 120 degrees, ... And, between the detection angles of 0 degrees to 60 degrees to 120 degrees,
The angular position of the rotor is estimated by calculating backward from the motor rotation speed.

On the other hand, the rotor 24 has
When the magnetic pole sensor signal is reversed to 60 degrees when changing from 0 degrees to 180 degrees, the magnetic pole sensor signal changes to 001 without changing from 011 to 010 after switching to 011. In this way, when the magnetic pole sensor signal changes in the opposite direction to the predetermined direction, it is determined that the magnetic pole sensor has reversed, and the angle recognition value of the rotor 24 is fixed to the angle (120 degrees) at the time of the reverse rotation.

When the reverse rotation occurs in this way, the angle recognition value of the rotor 24 is fixed to the angle when the reverse rotation occurs, and the exciting current to the exciting coil is controlled according to the fixed angle. Therefore, when the pedal is strongly depressed while the brake is applied, it is possible to suppress the excitation coil from being excited in the reverse direction, and it is possible to reduce vibration (pedal kickback) from the pedal.

By the way, in the conventional device, 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,
The control of the exciting current to the exciting coil does not actually match,
There was a problem that I felt a strong kickback.

Further, since it is judged that the magnetic pole sensor signal has reversed when the magnetic pole sensor signal changes in a direction opposite to the predetermined direction, it is possible to detect the occurrence of reverse rotation with a simple and low-cost configuration.

As the angle recognition value of the rotor 24, the magnetic pole sensor signal is detected a plurality of times in the forward rotation direction (in the present embodiment, 2
At the time of switching, the normal value is returned according to the magnetic pole sensor signal. That is, for example, if the magnetic pole sensor signal is 001
From 011 to 011 and then to 010, the angle recognition value changes from 120 degrees to 180 degrees.

In this way, the magnetic pole sensor signal becomes 2 in the normal direction.
Since the angle recognition value is returned to the normal value at the time of switching, the kickback can be reliably suppressed even when the magnetic pole sensor signal reciprocates at a certain switching point in the forward rotation direction and the reverse rotation direction.

The control of the angle recognition value of the rotor 24 is shown in FIG.
Further description will be given based on the flowchart of FIG. First, it is determined whether or not the magnetic pole sensor signal has changed (step S
1) If it has changed, it is judged whether or not the reverse rotation has occurred at the previous change of the sensor signal. If not, whether the reverse rotation has occurred this time based on the order of the change of the sensor signal. It is determined whether or not (steps S2, S
3)). When it is determined that the rotation is not the reverse rotation, the rotation is recognized as normal rotation (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. Rotor angle, and the above-mentioned exciting coil (motor coil) according to the rotor angle
Is excited (steps S6 to S7).

On the other hand, when it is determined in step S2 that the motor is rotating backward last time, when it is determined that the motor is rotating in reverse this time in step S3, and when it is determined that the motor is rotating in reverse in step S10, which will be described later, the rotor 24 is rotated in reverse. After being recognized, the angular position is fixed to the previous recognition angle (steps S8 and S9), and the motor coil is excited according to the fixed recognition angle (step S7).

If there is no change in the magnetic pole sensor signal at the step S1, it is judged whether or not the reverse rotation is in progress. If not, the angle is estimated (steps S10 and S1).
1), the estimated angle is added to the recognition angle to obtain a rotor angle, and the above-described exciting coil (motor coil) is excited according to the rotor angle (steps S6 to S7).

In the above-described embodiment, when the reverse rotation occurs, the recognition angle of the rotor 24 is fixed to the angle before the reverse rotation occurs. However, in addition to this, or alone, the motor auxiliary current command value when the reverse rotation occurs. May be fixed to the current value when reverse rotation occurs.

In this case, since the motor auxiliary current (exciting current) value does not increase even if the pedal effort increases, the exciting coil is not strongly excited in the reverse direction, and for example, the value is high. It is possible to reduce pedal vibration (rigid feeling) when the pedaling force starts. Further, it is possible to reduce the impact when the one-way clutch is engaged at the time of starting.

[Brief description of drawings]

FIG. 1 is a side view of an electrically assisted bicycle equipped with a drive motor control device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional side view of the drive motor.

FIG. 3 is a schematic cross-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 a sensor output and a rotor angle for explaining a motor reverse rotation process of the control device.

FIG. 6 is a block diagram of a motor reverse rotation process of the control device.

FIG. 7 is a motor reverse rotation processing flow of the control device.

[Explanation of symbols]

20 brushless DC motor 24 rotor 29a to 29c Magnetic pole sensor 31a-31c Excitation coil

Claims (4)

[Claims] 1. An angular position of a rotor is obtained for each switching point of a magnetic pole sensor signal, and the recognized angle of the rotor is determined by performing an angle correction between the obtained angular positions based on a motor rotation state, In a drive control device for a brushless DC motor configured to control an exciting current to an exciting coil based on the determined recognition angle, it is determined whether the rotor is forward or reverse based on the switching state of the magnetic pole sensor signal. A drive control device for a brushless DC motor, characterized in that, when it is determined that the motor has rotated in the reverse direction, the angle correction is not performed and the angular position at the time of detecting the reverse rotation is fixed and held. 2. The angle of the rotor is determined for each switching point of the magnetic pole sensor signal, and the recognized angle of the rotor is determined by performing angle correction between the determined angular positions based on the motor rotation state, In a drive control device for a brushless DC motor configured to control an exciting current to an exciting coil based on the determined recognition angle, it is determined whether the rotor is forward or reverse based on the switching state of the magnetic pole sensor signal. , A brushless D characterized by holding the exciting current value at the time of reverse rotation detection fixed when it is judged that reverse rotation has occurred.
C motor drive controller. 3. The drive of a brushless DC motor according to claim 1, wherein it is determined that the reverse rotation has occurred when the magnetic pole sensor signal is switched in a direction opposite to the order of normal rotation. Control device. 4. When the magnetic pole sensor signal is switched a plurality of times in the forward rotation direction after it is determined that the reverse rotation has occurred, the angular position of the rotor is set to a value corresponding to the magnetic pole sensor signal. A drive control device for a brushless DC motor, characterized in that the angle correction is restarted upon returning.