JP2024034436A - System and method for controlling stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine an abnormality in a stepping motor by simple control.

SOLUTION: A system controls a stepping motor. The stepping motor comprises a stator and a rotor. The stator comprises a coil in an A-phase and a coil in a B-phase. The rotor is arranged by facing the stator. The system comprises a controller and a sensor. The controller controls current of the coil in the A-phase and the coil in the B-phase. The sensor detects the current. The controller controls the current of the coil in the A-phase and the coil in the B-phase so that a stable point at the time when the rotor is rotated by a predetermined unit step angle deviates by a predetermined electric angle from a position confronting the coil in the A-phase and a position confronting the coil in the B-phase. The controller determines an abnormality when an absolute value of the current of the coil in the A-phase and the coil in the B-phase becomes smaller than a threshold.

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a system and method for controlling a stepper motor.

A stepping motor includes a stator and a rotor facing the stator. The stator includes an A-phase coil and a B-phase coil. A stepping motor controller controls currents in an A-phase coil and a B-phase coil. As a result, the A-phase coil and the B-phase coil are sequentially excited, causing the rotor to rotate.

2. Description of the Related Art In a stepping motor, a method is known in which an abnormality such as a disconnection of a coil is determined based on the current value of each coil. For example, the controller detects the current value flowing through each coil, and determines that there is an abnormality when the current value is 0 mA.

However, even if there is no disconnection in the coil, if the rotor is stopped at a position directly facing the A-phase coil, the current flowing through the B-phase coil will be 0 mA. In this case, the method of determining abnormality based on the current value of each coil as described above will result in false detection of abnormality.

Therefore, conventionally, countermeasures for preventing the above-mentioned false detections have been adopted in controllers. For example, the self-diagnosis control device for a stepping motor disclosed in Patent Document 1 detects the first signal output to port D11 by OR selection of drive signal #1 to the first coil and drive signal #2 to the second coil. To detect. Further, the second signal outputted to the port D12 is detected by OR selection of the drive signal #3 to the third coil and the drive signal #4 to the fourth coil. During normal operation, an H (High) signal is always output to port D11, and an L (Low) signal is always output to port D12, but the signals from each port may become H-L-H. , or LLL, the self-diagnosis control device determines that there is an abnormality.

Japanese Patent Application Publication No. 2000-116191

According to the abnormality detection method as described above, abnormality in the stepping motor can be accurately determined. However, control in the controller becomes complicated. An object of the present invention is to accurately determine an abnormality in a stepping motor by simple control.

A system according to one aspect of the present invention is a system that controls a stepping motor. A stepping motor includes a stator and a rotor. The stator includes an A-phase coil and a B-phase coil. The rotor is placed opposite the stator. The system includes a controller and a sensor. The controller controls currents in the A-phase coil and the B-phase coil. The sensor detects current. The controller rotates the A phase so that when the rotor is rotated by a predetermined unit step angle, a stable point deviates by a predetermined electrical angle from a position directly facing the A phase coil and a position directly facing the B phase coil. and the B-phase coil. The controller determines that an abnormality occurs when the absolute value of the current in the A-phase coil and the B-phase coil becomes smaller than a threshold value.

The predetermined electrical angle may be set such that the absolute value of the current between the A-phase coil and the B-phase coil at the stable point is greater than a threshold value. The predetermined electrical angle may be 22.5 degrees.

A method according to another aspect of the invention is a method of controlling a stepping motor. A stepping motor includes a stator and a rotor. The stator includes an A-phase coil and a B-phase coil. The rotor is placed opposite the stator. In this method, when the rotor is rotated by a predetermined unit step angle, the stable point is shifted by a predetermined electrical angle from the position directly facing the A-phase coil and the position directly facing the B-phase coil. The present invention includes controlling the currents in the phase coil and the B-phase coil, and determining that an abnormality occurs when the absolute value of the current in the A-phase coil and the B-phase coil becomes smaller than a threshold value.

According to the present invention, the stable point when the rotor is rotated by a predetermined unit step angle is shifted by a predetermined electrical angle from the position directly facing the A-phase coil and the position directly facing the B-phase coil. , the currents of the A-phase coil and the B-phase coil are controlled. Therefore, the rotor does not stop at a position directly facing the A-phase coil and a position directly facing the B-phase coil. Therefore, by determining the abnormality based on the current values of the A-phase coil and the B-phase coil, it is possible to accurately determine the abnormality. Thereby, an abnormality in the stepping motor can be accurately determined by simple control.

FIG. 1 is a block diagram showing the configuration of a system according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of a stepping motor. FIG. 2 is a block diagram showing the configuration of a stepping motor and a controller. FIG. 3 is a diagram showing drive currents input from a motor driver IC to each of an A-phase coil and a B-phase coil. 5 is a diagram showing the position of the stable point of the rotor when a drive current is applied to the A-phase coil and the B-phase coil as shown in FIG. 4. FIG.

Hereinafter, a system and method for controlling a stepping motor according to an embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a system 1 according to an embodiment. The system 1 includes a stepping motor 2 and a controller 3. The system 1 according to this embodiment performs idle speed control (ISC) of the engine 4.

As shown in FIG. 1, the engine 4 includes a throttle valve 11, an intake passage 12, an auxiliary air passage 13, and a flow control valve 14. The auxiliary air passage 13 is connected to the intake passage 12 so as to bypass the throttle valve 11. The flow rate control valve 14 is provided in the auxiliary air passage 13 and adjusts the flow rate of air passing through the auxiliary air passage 13. Flow control valve 14 is connected to stepping motor 2 . The controller 3 controls the stepping motor 2 to adjust the opening degree of the flow control valve 14. In idle speed control, the controller 3 controls the flow rate control valve 14 to adjust the flow rate of intake air so that the engine rotational speed in the idle operating state becomes a target rotational speed in consideration of the load and the like.

FIG. 2 is a schematic diagram showing the configuration of the stepping motor 2. As shown in FIG. As shown in FIG. 2, the stepping motor 2 includes a stator 15 and a rotor 16. Stator 15 includes A-phase coils 17A, 18A and B-phase coils 17B, 18B. The rotor 16 is arranged with the stator 15 facing each other.

FIG. 3 is a block diagram showing the configuration of the stepping motor 2 and the controller 3. As shown in FIG. The controller 3 controls the currents of the A-phase coils 17A, 18A and the B-phase coils 17B, 18B. Specifically, the controller 3 includes an ECU 21 and a motor driver IC 22. ECU 21 includes, for example, a microcomputer. The ECU 21 inputs a pulse signal for controlling the stepping motor 2 to the motor driver IC 22.

The motor driver IC 22 inputs drive current to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B in accordance with the input pulse signal. System 1 includes a first sensor 23 and a second sensor 24. The first sensor 23 detects the drive current to the A-phase coils 17A, 18A. The second sensor 24 detects the drive current to the B-phase coils 17B and 18B. The controller 3 acquires the drive currents to the coils detected by the sensors 23 and 24.

FIG. 4 is a diagram showing drive currents input from the motor driver IC 22 to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B, respectively. Note that in FIG. 4, the drive current is shown as a ratio to a predetermined reference current value Io.

The controller 3 determines that when the rotor 16 is rotated by a predetermined unit step angle, the stable point is a predetermined electrical angle from a position directly facing the A-phase coils 17A, 18A and a position directly facing the B-phase coils 17B, 18B. The drive currents to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B are controlled so that they are shifted.

FIG. 5 is a diagram showing the position of the stable point of the rotor 16 when a drive current is applied to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B as shown in FIG. As shown in FIG. 5, in this embodiment, the unit step angle of the stepping motor 2 is 45 degrees. The predetermined electrical angle is 22.5 degrees. That is, in the controller 3, when the rotor 16 is rotated by 45 degrees, the stable point deviates by 22.5 degrees from the position directly facing the A-phase coils 17A, 18A and the position directly facing the B-phase coils 17B, 18B. Thus, the drive currents to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B are controlled.

The positions directly facing the A-phase coils 17A and 18A are at 90 degrees and 270 degrees in electrical angle. The positions directly facing the B-phase coils 17B and 18B are at 0 degrees and 180 degrees in electrical angle. The stable points at which the rotor 16 is balanced and stationary due to the magnetic force of the A-phase coils 17A, 18A and the magnetic force of the B-phase coils 17B, 18B are 22.5 degrees, 67.5 degrees, 112.5 degrees, 157.5 degrees, The drive currents to the A-phase coils 17A and 18A and the drive currents to the B-phase coils 17B and 18B are set so that the angles are 202.5 degrees, 247.5 degrees, 292.5 degrees, and 337.5 degrees. There is.

Specifically, as shown in FIG. 4, at time T1, a drive current of -0.38Io is input to the A-phase coils 17A, 18A, and a drive current of -0.92Io is input to the B-phase coils 17B, 18B. Ru. As a result, the rotor 16 rotates toward a position at an electrical angle of 22.5 degrees in FIG. At time T2, a drive current of +0.38Io is input to the A-phase coils 17A, 18A, and a drive current of -0.92Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position of 67.5 electrical degrees in FIG. 5.

At time T3, a drive current of +0.92Io is input to the A-phase coils 17A, 18A, and a drive current of -0.38Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position of 112.5 electrical degrees in FIG. 5. At time T4, a drive current of +0.92Io is input to the A-phase coils 17A, 18A, and a drive current of +0.38Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position of 157.5 electrical degrees in FIG. 5 .

At time T5, a drive current of +0.38Io is input to the A-phase coils 17A, 18A, and a drive current of +0.92Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position of 202.5 electrical degrees in FIG. 5 . At time T6, a drive current of -0.38Io is input to the A-phase coils 17A, 18A, and a drive current of +0.92Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position at an electrical angle of 247.5 degrees in FIG.

At time T7, a drive current of -0.92Io is input to the A-phase coils 17A, 18A, and a drive current of +0.38Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position at an electrical angle of 292.5 degrees in FIG. At time T8, a drive current of -0.92Io is input to the A-phase coils 17A, 18A, and a drive current of -0.38Io is input to the B-phase coils 17B, 18B. As a result, the rotor 16 rotates toward a position at an electrical angle of 337.5 degrees in FIG. After time T9, the drive current is controlled in the same manner as times T1 to T8 described above.

Note that the absolute value of the drive current input to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B is larger than the threshold value TH1. That is, the predetermined electrical angle is set such that the absolute values of the currents in the A-phase coils 17A, 18A and the B-phase coils 17B, 18B at a stable point are larger than the threshold value TH1.

The controller 3 acquires the drive currents to the coils detected by the sensors 23 and 24. The controller 3 determines whether the stepping motor 2 is abnormal by comparing the drive current with a threshold value TH1. For example, the controller 3 determines that a disconnection has occurred in the A-phase coils 17A, 18A or the B-phase coils 17B, 18B when the drive current is smaller than the threshold value TH1.

When the controller 3 determines that a wire breakage has occurred consecutively a predetermined number of times, it determines that an abnormality has occurred in the stepping motor 2. When the controller 3 determines that an abnormality has occurred in the stepping motor 2, the controller 3 stops issuing commands to the stepping motor 2, for example. When the controller 3 determines that an abnormality has occurred in the stepping motor 2, the controller 3 may turn on a warning light. Alternatively, if the controller 3 determines that an abnormality has occurred in the stepping motor 2, the controller 3 may display a warning on the display.

In the system 1 according to the present embodiment, when the rotor 16 is rotated by a predetermined unit step angle, the stable point is a predetermined point from a position directly facing the A-phase coils 17A, 18A and a position directly facing the B-phase coils 17B, 18B. The currents in the A-phase coils 17A, 18A and the B-phase coils 17B, 18B are controlled so that they are shifted by an electrical angle of . Therefore, the rotor 16 does not stop at a position directly facing the A-phase coils 17A, 18A and a position directly facing the B-phase coils 17B, 18B. Therefore, the drive current to the coil does not become zero unless a wire break occurs in the coil.

Therefore, by determining the abnormality based on the drive currents to the A-phase coils 17A, 18A and the B-phase coils 17B, 18B, it is possible to accurately determine the abnormality. Thereby, an abnormality in the stepping motor 2 can be accurately determined by simple control.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the invention.

For example, the system 1 is not limited to one that controls the idling speed of the engine 4, but may be another system for controlling the stepping motor 2. The predetermined unit step angle is not limited to 45 degrees, and may be any other angle.

The predetermined electrical angle is not limited to 22.5 degrees, and may be any other angle. The predetermined electrical angle may be the quotient of 45 degrees divided by 2. For example, the predetermined electrical angle may be 11.25 degrees. That is, the controller 3 determines that when the rotor 16 is rotated by a predetermined unit step angle, the stable point is 11 electrical degrees from the position directly facing the A-phase coils 17A, 18A and the position directly facing the B-phase coils 17B, 18B. The drive currents of the A-phase coils 17A, 18A and the B-phase coils 17B, 18B may be controlled so that they are shifted by .25 degrees. Alternatively, the predetermined electrical angle may be less than 11.25 degrees.

According to the present invention, an abnormality in a stepping motor can be accurately determined through simple control.

2: Stepping motor 3: Controller 15: Stator 16: Rotor 17A, 18A: A phase coil 17B, 18B: B phase coil 23, 24: Sensor

Claims (6)

A system for controlling a stepping motor including a stator including an A-phase coil and a B-phase coil, and a rotor disposed facing the stator,
a controller that controls currents in the A-phase coil and the B-phase coil;
a sensor that detects the current;
Equipped with
The controller includes:
The A is configured such that a stable point when the rotor is rotated by a predetermined unit step angle is shifted by a predetermined electrical angle from a position directly facing the A-phase coil and a position directly facing the B-phase coil. controlling the current between the phase coil and the B-phase coil;
When the absolute value of the current in the A-phase coil and the B-phase coil is smaller than a threshold value, it is determined that there is an abnormality.
system. The predetermined electrical angle is set such that the absolute value of the current between the A-phase coil and the B-phase coil at the stable point is greater than the threshold value.
The system of claim 1. The predetermined electrical angle is 22.5 degrees.
The system of claim 1. A method for controlling a stepping motor including a stator including an A-phase coil and a B-phase coil, and a rotor disposed facing the stator, the method comprising:
The A is configured such that a stable point when the rotor is rotated by a predetermined unit step angle is shifted by a predetermined electrical angle from a position directly facing the A-phase coil and a position directly facing the B-phase coil. controlling currents in the phase coil and the B-phase coil;
determining that there is an abnormality when the absolute value of the current in the A-phase coil and the B-phase coil is smaller than a threshold;
How to prepare. The predetermined electrical angle is set such that the absolute value of the current between the A-phase coil and the B-phase coil at the stable point during normal operation is larger than the threshold value.
The method according to claim 4. The predetermined electrical angle is 22.5 degrees.
The method according to claim 4.

Images