WO2022255491A1

WO2022255491A1 - Motor control device

Info

Publication number: WO2022255491A1
Application number: PCT/JP2022/022672
Authority: WO
Inventors: 祐貴伊達; 亮介小栗; 将太藤井
Original assignee: 株式会社デンソー
Priority date: 2021-06-04
Filing date: 2022-06-03
Publication date: 2022-12-08
Also published as: JP2022186494A

Abstract

A motor control device (11) comprises a control unit (21) that controls a direct-current motor M and that calculates the rotational amount of the direct-current motor M on the basis of the number of peaks in a detected electric current waveform. The control unit (21) includes: a predicted cycle calculating unit (23) that calculates the rotational speed at a time of startup on the basis of the electric current waveform at the time of startup, and calculates a predicted cycle for peaks of the electric current waveform on the basis of the calculated rotational speed; a missing peak detecting unit (24) that detects instances of missing peaks of the detected electric current waveform on the basis of the predicted cycle calculated by the predicted cycle calculating unit (23); and a rotational amount calculating unit (25) that, in accordance with the instances of missing peaks detected by the missing peak detecting unit (24), corrects the number of peaks of the detected electric current waveform, and calculates the rotational amount of the direct-current motor (M).

Description

motor controller

Cross-reference to related applications

This application is based on Japanese Application No. 2021-094751 filed on June 4, 2021, and the contents thereof are incorporated herein.

The present disclosure relates to a motor control device.

Conventionally, in a DC motor having a commutator and power supply brushes that are in sliding contact with the commutator, ripples occur in current and induced voltage due to switching of the contact state of the power supply brushes with the commutator segments. Some motor control devices include a control unit that detects peaks in a current waveform or an induced voltage waveform and calculates the amount of rotation of the DC motor based on the number of peaks. In such a motor control device, since a large number of commutator segments are provided in the circumferential direction, it is possible to detect a fine rotation angle of the rotor of the DC motor and to calculate the amount of rotation with high accuracy.

However, in a DC motor, for example, the switching of the contact state of the power supply brush to the commutator segment becomes uneven, so the amplitude of the waveform is not constant. A so-called missing peak, which cannot be detected, may occur.

Therefore, for example, while detecting the peak of the waveform, there is a technique that compares the period with the average ripple period, which is the period of the peak during the past steady operation, and detects and corrects the omission of the peak (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2011-109880

However, with the above-described peak dropout detection technology, it is not possible to use the average ripple period during steady-state operation at startup, more specifically, during speed fluctuations during the period from startup until the rotation speed stabilizes. , there is a problem that the amount of rotation cannot be calculated with high accuracy.

An object of the present disclosure is to provide a motor control device capable of calculating a rotation amount at startup with high accuracy.
In one aspect of the present disclosure, a motor control device is a motor control device that includes a control unit that controls a DC motor and calculates an amount of rotation of the DC motor based on the number of peaks of a detected current waveform, a prediction cycle calculation unit for calculating a rotation speed at startup based on a current waveform at startup, and calculating a prediction cycle of a peak of the current waveform based on the calculated rotation speed; a peak missing detection unit for detecting missing peaks in the detected current waveform based on the prediction period calculated by the unit; and a rotation amount calculation unit that calculates the rotation amount of the DC motor by correcting the number of .

According to the same configuration, the prediction cycle calculation unit calculates the rotation speed at startup based on the current waveform at startup, and calculates the peak prediction cycle of the current waveform based on the calculated rotation speed. Further, the missing peak of the detected current waveform is detected by the missing peak detection unit based on the prediction cycle calculated by the prediction cycle calculation unit. Then, the amount of rotation of the DC motor is calculated by correcting the number of detected peaks of the current waveform according to the missing peak detected by the peak missing detection unit by the rotation amount calculating unit, so that the amount of rotation of the DC motor is calculated. The amount of rotation can be calculated with high accuracy.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a schematic circuit diagram of a motor control device in one embodiment; FIG. 2 is a flow diagram for explaining calculation processing of the control unit in one embodiment, FIG. 3 is a characteristic diagram of current versus time in one embodiment; FIG. 4 is a characteristic diagram of rotation speed with respect to current in one embodiment, FIG. 5 is a characteristic diagram of rotation speed against time in one embodiment, FIG. 6 is a characteristic diagram of period versus time in one embodiment.

An embodiment of the motor control device 11 will be described below with reference to FIGS. 1 to 6. FIG.
As shown in FIG. 1, a motor controller 11 is connected to a DC motor M. As shown in FIG. The DC motor M includes a commutator 13 in which commutator segments 12 are arranged in parallel in the circumferential direction, and a pair of power supply brushes 14 that are in sliding contact with the commutator 13 . The DC motor M has a rotor that is drivingly connected to the driven part 15 .

In the DC motor M, each time the power supply brush 14 in sliding contact with the commutator 13 is switched between the commutator segments 12, that is, the power supply brush 14 in contact with one commutator segment 12 when the commutator 13 rotates The adjacent commutator segments 12 are also in contact with each other, and the resistance value changes each time the commutator segments 12 are crossed, thereby generating a current ripple waveform. A peak appears.

The motor control device 11 includes a control section 21 connected to a pair of power supply brushes 14 and an ammeter 22 connected between one of the power supply brushes 14 and the control section 21 .
The control unit 21 includes 1) one or more processors that execute various processes according to a computer program (software), and 2) an application specific integrated circuit (ASIC) that executes at least part of the various processes. It may be configured as circuitry including one or more dedicated hardware circuits, or 3) combinations thereof. A processor includes a CPU and memory, such as RAM and ROM, which stores program code or instructions configured to cause the CPU to perform processes. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer.

The control unit 21 supplies a driving current to the pair of power supply brushes 14 to control the DC motor M, and calculates the amount of rotation of the DC motor M based on the number of peaks of the current waveform detected by the ammeter 22. do.

Specifically, the control unit 21 includes a prediction period calculation unit 23 , a peak missing detection unit 24 , and a rotation amount calculation unit 25 .
The prediction period calculation unit 23 calculates the rotation speed at startup based on the current waveform at startup, more specifically, the period from startup until the rotation speed stabilizes, and calculates the peak of the current waveform based on the calculated rotation speed. , that is, the prediction period between peaks.

The peak dropout detector 24 detects the peak dropout of the detected current waveform based on the prediction cycle calculated by the prediction cycle calculator 23 .
The rotation amount calculation unit 25 calculates the rotation amount of the DC motor M by correcting the number of detected peaks in the current waveform according to the peak dropout detected by the peak dropout detection unit 24 .

Next, specific operations and actions of the control section 21 described above will be described with reference to FIG.
As shown in FIG. 2, when starting the DC motor M, the control unit 21 performs the calculation process of step S1 and subsequent steps.

As shown in FIG. 3, in step S1, the control unit 21 holds the current waveform X1 detected by the ammeter 22 at the time of start-up, more specifically, during the period from start-up until the rotation speed stabilizes. Move to S2.

In step S2, the predicted period calculator 23 of the controller 21 calculates the rotation speed at startup based on the current waveform X1 at startup, and calculates the predicted period Y1 of the peak of the current waveform X1 based on the calculated rotation speed. After calculating, the process proceeds to step S3.

Specifically, in step S2, the prediction cycle calculation unit 23 first converts the current waveform X1 at startup into a quadratic approximation formula X2. In addition, in FIG. 3, the waveform of the quadratic approximation formula X2 is illustrated with a dashed line.

Next, as shown in FIG. 4, the prediction period calculation unit 23 creates a characteristic map X3 from the inrush current I1, the steady current I2, and the steady rotation speed V1. Note that the inrush current I1 is the maximum current value that flows immediately after the drive current is supplied to the DC motor M in the stopped state, and the steady-state current I2 is the steady-state rotation speed V1 at which the rotation speed of the DC motor M is stable. It is the value of the current that flows. That is, the predicted period calculator 23 creates a linear function characteristic map X3 from the inrush current I1 when the rotation speed is 0 and the steady-state current I2 when the rotation speed is V1.

Next, as shown in FIG. 5, the prediction period calculation unit 23 calculates the rotation speed V2 at the time of starting from the quadratic approximation formula X2 based on the characteristic map X3.
Then, as shown in FIG. 6, the prediction cycle calculation unit 23 calculates the prediction cycle Y1, which is the reciprocal of the rotation speed V2, more specifically, the prediction cycle Y1 of the peak of the current waveform X1, based on the rotation speed V2 at the time of startup. do.

Next, in step S3, the peak dropout detection unit 24 of the control unit 21 detects the peak dropout of the detected current waveform based on the prediction period Y1, and the process proceeds to step S4.
Specifically, as shown in FIG. 6, the peak missing detection unit 24 first calculates period threshold values Z1 and Z2 using the prediction period Y1 and the integral multiple prediction periods Y2 and Y3, which are integral multiples of the prediction period Y1. do. Specifically, the peak missing detection unit 24 of the present embodiment calculates integral multiple prediction cycles Y2 and Y3 that are at least twice and three times the prediction cycle Y1, and doubles the intermediate value between them. It is calculated as period threshold values Z1 and Z2 corresponding to 3 times. In FIG. 6, the lower limit considered to be within the range of the prediction cycle Y1 is illustrated as the lower limit threshold Z3, and the upper limit considered to be within the range of the integral multiple prediction cycle Y3 corresponding to three times the prediction cycle Y1 is illustrated as the upper threshold Z4. Illustrated. The lower threshold value Z3 is, for example, a value lower than the prediction cycle Y1 by half a cycle of the prediction cycle Y1, and the upper threshold value Z4 is, for example, a value higher than the integer multiple prediction cycle Y3 corresponding to 3 times by a half cycle of the prediction cycle Y1. can be considered.

Then, the peak dropout detection unit 24 compares the calculated period threshold values Z1 and Z2 with the detected peak period P of the current waveform to detect the peak dropout of the current waveform. Specifically, the peak missing detection unit 24 compares the calculated plurality of period threshold values Z1 and Z2 with the detected peak period P of the current waveform X1 to detect the peak missing of the current waveform in a plurality of stages. Specifically, the peak missing detection unit 24 of the present embodiment detects, for example, a peak whose amplitude is equal to or greater than a certain value from the current waveform X1, and sets the period P of the peak to the lower threshold value Z3, the period threshold values Z1 and Z2, and the upper Compare with threshold Z4. Then, for example, when the peak cycle P is between the lower limit threshold value Z3 and the cycle threshold value Z1, the peak dropout detection unit 24 determines that there is no peak dropout. For example, when the peak cycle P is between the cycle threshold value Z1 and the cycle threshold value Z2, the peak dropout detection unit 24 determines that the peak dropout has occurred only once. For example, when the peak cycle P is between the cycle threshold value Z2 and the upper limit threshold value Z4, the peak dropout detection unit 24 determines that the peak dropout has occurred twice in succession.

Next, in step S4, the rotation amount calculation unit 25 of the control unit 21 corrects the number of peaks of the detected current waveform X1 according to the peak dropout detected by the peak dropout detection unit 24, and corrects the number of peaks of the DC motor M is calculated, and the calculation process ends.

Specifically, the rotation amount calculation unit 25 corrects the number of peaks of the detected current waveform X1 in multiple steps according to the peak dropout detected in multiple steps by the peak dropout detection unit 24, and rotates the DC motor M. Calculate quantity. That is, when the peak dropout detection unit 24 determines that the peak dropout has occurred only once, the rotation amount calculation unit 25 corrects the number of peaks only once, and the peak dropout detection unit 24 corrects the number of peaks. If it is determined that the omission has occurred twice in succession, the number of peaks is corrected twice. Then, the rotation amount calculator 25 calculates the rotation amount of the DC motor M based on the corrected number of peaks.

When the amount of rotation of the DC motor M is calculated in this way, the calculation process is completed. becomes possible.

Next, the effects of the above embodiment will be described below.
(1) The predicted period calculator 23 calculates the rotation speed V2 at startup based on the current waveform X1 at startup, and calculates the predicted period Y1 of the peak of the current waveform X1 based on the calculated rotation speed V2. . Further, the missing peak of the detected current waveform X1 is detected by the peak missing detection unit 24 based on the prediction cycle Y1 calculated by the prediction cycle calculation unit 23 . Then, the amount of rotation of the DC motor M is calculated by the amount of rotation calculator 25 by correcting the number of detected peaks of the current waveform X1 according to the missing peak detected by the peak missing detection unit 24. , the amount of rotation at startup can be calculated with high accuracy.

(2) The peak missing detection unit 24 calculates period threshold values Z1 and Z2 corresponding to at least two and three times the predicted period Y1. are compared to detect a missing peak in the current waveform in a plurality of steps. Then, the number of detected peaks of the current waveform X1 is corrected in multiple steps by the rotation amount calculating unit 25 in accordance with the missing peaks detected in multiple steps by the peak missing detection unit 24, and the DC motor M rotates. Amount is calculated. Therefore, for example, even if peak omission occurs twice in succession, the number of peaks is corrected twice, and the amount of rotation can be calculated with high accuracy.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- The prediction period calculation part 23 of the above-described embodiment may be configured to calculate the prediction period Y1 of the peak of the current waveform X1 by other calculations or the like.

The peak dropout detector 24 of the above embodiment may be configured to detect the peak dropout of the detected current waveform X1 by other calculations or the like.
For example, the peak dropout detection unit 24 of the above embodiment is configured to detect peak dropouts in two stages. It is good also as a structure which carries out. Further, the peak dropout detection unit 24 may be configured to detect peak dropouts in one stage, that is, to determine that peak dropouts have occurred only once even if peak dropouts have occurred twice in succession. By doing so, the amount of calculation of the peak missing detection unit 24 and the amount of rotation calculation unit 25 can be reduced.

·Although not particularly mentioned in the above embodiment, the amount of rotation of the DC motor M other than at startup may be detected or calculated by other methods. That is, the above-described method of calculating the amount of rotation at startup is a method of calculating the amount of rotation suitable for speed fluctuations at the time of startup. It may be detected or calculated by a method.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to those examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

Claims

A motor control device (11) comprising a control section (21) for controlling a DC motor (M) and calculating the amount of rotation of the DC motor based on the number of peaks of a detected current waveform (X1), ,
The control unit
a predicted period calculation unit (23) that calculates a rotation speed (V2) at startup based on the current waveform at startup and calculates a predicted period (Y1) of the peak of the current waveform based on the calculated rotation speed;
a peak missing detection unit (24) for detecting a missing peak in the detected current waveform based on the prediction cycle calculated by the prediction cycle calculation unit;
a rotation amount calculation unit (25) for calculating the amount of rotation of the DC motor by correcting the number of peaks of the detected current waveform according to the peak dropout detected by the peak dropout detection unit. Device.
The prediction period calculation unit converts the current waveform at startup into a quadratic approximation formula (X2), and creates a characteristic map ( 2. The motor control device according to claim 1, wherein the rotational speed at startup is calculated from the quadratic approximation based on X3), and the predicted cycle of the peak of the current waveform is calculated based on the calculated rotational speed at startup.
The peak missing detection unit calculates period threshold values (Z1, Z2) based on the prediction period calculated by the prediction period calculation unit and the integer multiple prediction period (Y2, Y3) that is an integral multiple of the prediction period. 3. The motor control device according to claim 1, wherein the calculated period threshold is compared with the period (P) of the peak of the detected current waveform to detect the omission of the peak of the current waveform.
The peak missing detection unit calculates period thresholds corresponding to at least two and three times the predicted period, compares the calculated plurality of period thresholds with the period of the detected peak of the current waveform, and compares the period of the peak of the current waveform. 4. The motor control device according to claim 3, wherein the disconnection is detected in a plurality of steps.
The rotation amount calculation unit calculates the rotation amount of the DC motor by correcting the number of detected peaks of the current waveform in multiple steps according to the peak dropouts detected in multiple steps by the peak dropout detection unit. 5. A motor control device according to claim 4.