JP7775147B2 - Motor drive control device, motor unit, and motor drive control method - Google Patents

Description

The present invention relates to a motor drive control device, a motor unit, and a motor drive control method.

Conventionally, motor drive control devices that externally input a PWM (Pulse Width Modulation) signal with a duty ratio corresponding to the motor's target rotation speed are known (see, for example, Patent Document 1). The motor drive IC (Integrated Circuit) in Patent Document 1 shows a configuration in which the PWM signal is smoothed by a filter circuit before being input.

Japanese Patent Application Laid-Open No. 2016-226263

However, as in Patent Document 1, if a disturbance such as noise occurs for some reason when a PWM signal is input from an external device as a target speed command, the duty ratio of the PWM signal may change relatively significantly due to the influence of the disturbance, resulting in an unstable target speed command value, which may result in an incorrect target speed command value and an inability to achieve the target motor rotation speed.
Furthermore, even when the drive command received from outside is not a target speed command but a target position command, if the external target position command value changes suddenly, there is a problem in that the target position command value becomes unstable, just as the target speed command value becomes unstable. For example, when the rotational torque is high, the load at the start of rotation is high so the motor does not rotate immediately, and it begins to rotate only after the motor drive output becomes large, so the target position command value can easily be exceeded, and it may become necessary to rotate in the reverse direction.

The inventors of this application therefore recognized the need for a new motor drive control technology that can maintain stable motor rotation even when external drive commands change suddenly.

The present invention aims to solve the above-mentioned problems by providing a motor drive control device, motor unit, and motor drive control method that can maintain stable rotational operation of the motor even when external drive commands change suddenly.

A motor drive control device according to a representative embodiment of the present invention includes a motor drive unit that applies a voltage to the motor coil to drive the motor based on a drive control signal for controlling the drive of the motor; a control unit that generates the drive control signal based on an operation command signal for the motor and outputs the drive control signal to the motor drive unit; and an operation command signal output circuit that receives an external drive command signal and outputs the operation command signal to the control unit. The control unit has a command value conversion processing unit that converts the operation command included in the operation command signal into a target command value, and a follow-up drive control signal generation unit that acquires the target command value from the command value conversion processing unit and, when the acquired target command value changes, generates the drive control signal based on a follow-up command value, which is a command value that has been subjected to follow-up processing so that the acquired target command value changes by a predetermined percentage of the amount of change over a predetermined number of times.

One aspect of the present invention provides a motor drive control device, motor unit, and motor drive control method that can maintain stable rotational operation of a motor even when external drive commands change suddenly.

1 is a diagram showing a specific example of the configuration of a motor unit 1 equipped with a motor drive control device 20 according to a first embodiment. 2 is a block diagram showing the internal configuration of a control unit 200 of a motor drive control device 20 according to the first embodiment. FIG. 10 is a diagram showing an example of a change in a follow-up command value S3 when a target speed command value S2 is changed. FIG. FIG. 10 is a diagram showing another example of a change in the follow-up command value S3 when the target speed command value S2 is changed. 10 is a flowchart of a follow-up process by a speed command follow-up processing unit 221 according to the first embodiment. 3 is a diagram for explaining an example of signal waveforms between components in the control unit 200. FIG. 10 is a diagram showing a comparison of a command value obtained by the tracking process of the first embodiment with a command value obtained by conventional moving average processing when a speed command value is changed; FIG. FIG. 6B is a diagram visually showing the change in the command value of FIG. 6A. 10A and 10B are diagrams illustrating a comparison of command values obtained by the tracking process according to the first embodiment with command values obtained by conventional moving average processing when noise is superimposed; FIG. 7B is a diagram visually showing the change in the command value of FIG. 7A. FIG. 10 is a diagram showing a specific example of the configuration of a motor unit 1A equipped with a motor drive control device 20A according to a second embodiment. FIG. 10 is a block diagram showing the internal configuration of a control unit 200A of a motor drive control device 20A according to a second embodiment. 10 is a flowchart of a follow-up process according to a second embodiment. FIG. 10 is a diagram showing an example of a change in rotational position (current position) when a target position command value is changed in a conventional motor drive control device. 10A and 10B are diagrams illustrating an example of a change in a follow-up command value S3a and a change in a rotational position (current position) when a target position command value S2a is changed in a motor drive control device 20A according to the second embodiment.

1. Overview of the Embodiments First, an overview of representative embodiments of the invention disclosed in this application will be described. Note that in the following description, as an example, reference numerals in the drawings corresponding to components of the invention are written in parentheses.

[1] A motor drive control device (20, 20A) according to a representative embodiment of the present invention comprises a motor drive unit (300) that applies a voltage to the coil of a motor (10) to drive the motor based on a drive control signal (Sd) for controlling the drive of the motor, a control unit (200, 200A) that generates the drive control signal (Sd) based on an operation command signal (Sc1, Sc2) of the motor and outputs the drive control signal to the motor drive unit, and an operation command signal (PWM, STMP) that receives an external drive command signal and outputs the operation command signal to the control unit. The control unit includes an output circuit (100, 100A), and the control unit includes a command value conversion processing unit (210, 210A) that converts the operation command included in the operation command signal into a target command value (S2, S2a), and a follow-up drive control signal generation unit (220, 220A) that acquires the target command value from the command value conversion processing unit and, when the acquired target command value changes, generates the drive control signal based on a follow-up command value (S3, S3a), which is a command value that has been subjected to follow-up processing so that the acquired target command value changes by a predetermined rate of change over a predetermined number of times.

[2] In the motor drive control device described in [1] above, the follow-up drive control signal generation unit may include a speed command follow-up processing unit that determines that the acquired target speed command value has changed when there is a difference between the current speed command value, which is the previous follow-up command value, and the target speed command value, which is the newly acquired target command value, and performs follow-up processing to set a new follow-up command value that is the current speed command value that is closer to the target speed command value by a preset value at predetermined follow-up processing intervals until the current speed command value reaches the target speed command value; and a drive control signal generation unit that generates the drive control signal based on the new follow-up command value.

[3] In the motor drive control device described in [1] above, the follow-up drive control signal generation unit may include a speed command follow-up processing unit that determines that the acquired target speed command value has changed when there is a difference between the current speed command value, which is the previous follow-up command value, and the target speed command value, which is the newly acquired target command value, and performs follow-up processing to set a new follow-up command value that approaches the current speed command value to the target speed command value by a value determined according to the difference at predetermined follow-up processing intervals until the current speed command value reaches the target speed command value; and a drive control signal generation unit that generates the drive control signal based on the new follow-up command value.

[4] In the motor drive control device described in [3] above, the speed command tracking processing unit may set the predetermined tracking processing interval to a smaller value as the difference becomes smaller, and set the value that brings the current speed command value closer to the target speed command value to a larger value.

[5] In the motor drive control device described in [1] above, the follow-up drive control signal generation unit may include a position command follow-up processing unit that determines that the acquired target position command value has changed when there is a difference between the current position command value, which is the previous follow-up command value, and the target position command value, which is the newly acquired target command value, and performs follow-up processing to set a new follow-up command value that approaches the current position command value to the target position command value by a preset value at predetermined follow-up processing intervals until the current position command value reaches the target position command value; and a drive control signal generation unit that generates the drive control signal based on the new follow-up command value.

[6] In the motor drive control device described in [1] above, the follow-up drive control signal generation unit may include a position command follow-up processing unit that determines that the acquired target position command value has changed when there is a difference between a current position command value, which is the previous follow-up command value, and a target position command value, which is a newly acquired target command value, and performs follow-up processing to set a new follow-up command value that brings the current position command value closer to the target position command value by a value determined according to the difference at predetermined follow-up processing intervals until the current position command value reaches the target position command value; and a drive control signal generation unit that generates the drive control signal based on the new follow-up command value.

[7] A motor unit according to a representative embodiment of the present invention comprises the motor drive control device described in any one of [1] to [6] above and the motor.

[8] A motor drive control method according to a representative embodiment of the present invention is a motor drive control method using a motor drive control device that includes a motor drive unit that applies a voltage to the motor coil based on a drive control signal for controlling the drive of the motor to drive the motor, a control unit that generates the drive control signal based on an operation command signal for the motor and outputs the drive control signal to the motor drive unit, and an operation command signal output circuit that receives an external drive command signal and outputs the operation command signal to the control unit, and includes a command value conversion processing step in which the control unit converts the operation command included in the operation command signal into a target command value, and a follow-up drive control signal generation step in which, when the target command value converted in the command value conversion processing step changes, the control unit generates the drive control signal based on a follow-up command value that is a command value that has been subjected to follow-up processing so as to change a predetermined number of times at a predetermined rate of change in the acquired target command value.

2. Specific Examples of Embodiments Specific examples of embodiments of the present invention will be described below with reference to the drawings. In the following description, components common to the embodiments will be designated by the same reference numerals, and repeated description will be omitted.

First Embodiment
FIG. 1 is a diagram showing a specific example of the configuration of a motor unit 1 equipped with a motor drive control device 20 according to a first embodiment.

The motor unit 1 shown in Figure 1 includes a motor 10 and a motor drive control device 20.

Motor 10 is a motor having at least one coil. For example, motor 10 is a brushless DC motor having three-phase (U-phase, V-phase, and W-phase) coils (windings) Lu, Lv, and Lw.

The motor drive control device 20 is a device that controls the drive of the motor 10. The motor drive control device 20 drives the motor 10 based on, for example, a rotation speed command (drive command) contained in a PWM signal (an example of a drive command signal) PWM from the higher-level device 2.

Specifically, the motor drive control device 20 includes a PWM output circuit (an example of an operation command signal output circuit) 100, a control unit 200, and a motor drive unit 300. The motor drive control device 20 receives a DC voltage from an external DC power supply (not shown). The DC voltage is supplied to a power supply line (not shown) within the motor drive control device 20, for example, via a protection circuit or the like, and is input to the PWM output circuit 100, the control unit 200, and the motor drive unit 300 via the power supply line.

The motor drive unit 300 is a circuit that drives the motor 10 based on a drive control signal Sd output from the control unit 200 (described below). The drive control signal Sd is a signal for controlling the drive of the motor 10. For example, the drive control signal Sd is a PWM signal for driving the motor 10.

The motor drive unit 300 switches the connection of the motor 10 coil between the power supply voltage and ground potential based on the drive control signal Sd, thereby switching the direction of the coil current and rotating the motor 10.

The control unit 200 is a circuit for comprehensively controlling the operation of the motor drive control device 20. In the first embodiment, the control unit 200 is, for example, a program processing device configured as shown in FIG. 1, in which a timer with input capture function, ROM, RAM, a clock generation circuit, a processor (such as a CPU), and an input/output I/F circuit are connected to each other via a bus or dedicated lines. For example, the control unit 200 is a microcontroller (MCU: Micro Controller Unit). The control unit 200 may also include various storage devices such as flash memory, a timer as a counter, an A/D conversion circuit, a D/A conversion circuit, and other peripheral circuits.

The control unit 200 and motor drive unit 300 may be packaged as a single semiconductor integrated circuit (IC), or may be packaged as separate integrated circuits mounted on a circuit board and electrically connected to each other on the circuit board.

The PWM output circuit 100 is a circuit that receives a PWM signal (an example of a drive command signal) PWM from an external device (e.g., a higher-level device 2), generates a PWM signal (an example of an operation command signal) Sc1 that includes an operation command indicating a target value for the operation of the motor 10 (in this embodiment, the rotational speed), and outputs this signal to the control unit 200.

The control unit 200 has the basic function of controlling the energization of the motor 10 by generating a drive control signal Sd and providing it to the motor drive unit 300. Specifically, the control unit 200 generates a drive control signal Sd based on the input PWM signal Sc1 so that the motor 10 is in the operating state specified by the operation command included in the PWM signal Sc1 and provides it to the motor drive unit 300.

In addition to the above basic functions, the control unit 200 also has a function (hereinafter also referred to as the "tracking processing function") of generating a drive control signal Sd corresponding to a command value that has been tracked so that it changes a predetermined number of times at a predetermined rate of change in the target command value when the target command value (in this embodiment, the target speed command value) specified in the operation command included in the PWM signal Sc1 changes.

FIG. 2 is a block diagram showing the internal configuration of the control unit 200 of the motor drive control device 20 according to the first embodiment.
As shown in FIG. 2, the control unit 200 has, as functional units for realizing the above-mentioned functions, for example, a command value conversion processing unit 210 having a duty comparison unit 211 and a speed command conversion unit 212, a tracking drive control signal generation unit 220 having a speed command tracking processing unit 221 and a drive control signal generation unit 222, and a memory unit 230.

Each of the above-mentioned functional units of the control unit 200 is realized, for example, by program processing of the MCU that serves as the control unit 200. Specifically, each of the above-mentioned functional units is realized by a processor that constitutes the MCU that serves as the control unit 200 performing various calculations in accordance with programs stored in memory and controlling the various peripheral circuits that make up the MCU.

The command value conversion processing unit 210 receives the PWM signal Sc1 input from the PWM output circuit 100. The PWM signal Sc1 is a signal that indicates a target value for the operation of the motor 10, and includes, for example, a signal that indicates the target rotational speed of the motor 10.

The command value conversion processing unit 210 analyzes the target rotation speed specified by the PWM signal Sc1 and outputs information about the rotation speed corresponding to the duty ratio as the target speed command value S2. As a specific example, if the input PWM signal Sc1 is a PWM signal having a duty ratio corresponding to the target rotation speed, the duty comparison unit 211 in the command value conversion processing unit 210 captures the PWM signal input as the PWM signal Sc1 at the timing of the internal clock signal CLK and outputs it to the speed command conversion unit 212 as a duty ratio signal S1 indicating the duty ratio of the PWM signal. Upon receiving the duty ratio signal S1, the speed command conversion unit 212 outputs information about the rotation speed corresponding to the duty ratio of the PWM signal Sc1 as the target speed command value S2.

When the target speed command value S2 acquired from the command value conversion processing unit 210 changes, the follow-up drive control signal generation unit 220 generates a drive control signal Sd based on a follow-up command value S3, which is a command value that has been subjected to follow-up processing so that the obtained target speed command value S2 changes at a predetermined rate over a predetermined number of times. Specifically, the speed command follow-up processing unit 221 calculates the follow-up command value S3 through follow-up processing, and the drive control signal generation unit 222 calculates the operation amount of the motor 10 so that the rotational speed of the motor 10 matches the rotational speed specified by the follow-up command value S3, and generates a drive control signal Sd based on the calculated operation amount. Details of the follow-up processing, which is one of the functions of the follow-up drive control signal generation unit 220, will be described later.

The memory unit 230 stores the addition/subtraction unit value and addition/subtraction interval referenced in the tracking process. The addition/subtraction unit value is the magnitude of the speed that is added or subtracted as a predetermined percentage of the change in the target speed command value S2, and is set according to the specifications of the motor 10 and the motor drive unit 300. The addition/subtraction interval is the time interval (hereinafter also referred to as the "tracking process interval") at which a predetermined percentage of the change in the target speed command value S2 is changed (added or subtracted), and is set according to the specifications of the motor 10 and the motor drive unit 300.

When the target speed command value S2 acquired from the command value conversion processing unit 210 changes, the speed command tracking processing unit 221 performs tracking processing by referencing the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230 as necessary, to calculate a tracking command value S3, and outputs this to the drive control signal generation unit 222. When the target speed command value S2 acquired from the command value conversion processing unit 210 does not change, the speed command tracking processing unit 221 outputs the same speed command value as before as the tracking command value S3 to the drive control signal generation unit 222.

The drive control signal generation unit 222 calculates the operation amount of the motor 10 based on the rotation speed and the operation interval specified by the operation command value S3 received from the speed command operation processing unit 221, generates a PWM signal having a PWM period and an ON period determined based on the calculated operation amount as the drive control signal Sd, and outputs it to the motor drive unit 300.

The motor drive unit 300 is a circuit that drives the motor 10 based on the drive control signal Sd output from the drive control signal generation unit 222 of the control unit 200. The drive control signal Sd is a PWM signal having a PWM period and on-period corresponding to the rotation speed, which is the tracking command value S3. The motor drive unit 300 switches the connection destination of the motor 10 coil between the power supply voltage and ground potential based on the PWM signal of the drive control signal Sd, thereby switching the direction of the coil current and rotating the motor 10 at the rotation speed, which is the tracking command value S3.

Here, we will further explain how the speed command tracking processing unit 221 calculates the tracking command value S3 through tracking processing.

FIG. 3A is a diagram showing an example of a change in the follow-up command value S3 when the target speed command value S2 is changed.
FIG. 3B is a diagram showing another example of a change in the follow-up command value S3 when the target speed command value S2 is changed.

The speed command tracking processing unit 221 executes tracking processing when the target speed command value S2 acquired from the command value conversion processing unit 210 (speed command conversion unit 212) changes. The tracking processing is a process in which, even when the target speed command value S2 changes, the amount of change in the target speed command value S2 is not changed all at once, but a tracking command value S3 is generated that changes over a predetermined number of times at a predetermined rate of the amount of change in the acquired target speed command value S2, and is output as a new tracking command value S3 to the drive control signal generation unit 222.

Specifically, if there is a difference between the current speed command value, which is the previous follow-up command value S3, and the newly acquired command value, which is the target speed command value S2, the speed command follow-up processing unit 221 determines that the acquired target speed command value S2 has changed and executes follow-up processing.

As a tracking process, the speed command tracking processing unit 221 specifically calculates a tracking command value S3 that changes with respect to the target speed command value S2 as shown in Figure 3A or 3B, and outputs this to the drive control signal generation unit 222.

In the tracking process shown in FIG. 3A, the speed command tracking processing unit 221 sets a new tracking command value S3 by bringing the current speed command value, which is the previous tracking command value S3, closer to the target speed command value S2 by a preset value at each specified tracking process interval until the current speed command value reaches the target speed command value S2.

In the tracking process shown in FIG. 3B, the speed command tracking processing unit 221 sets a new tracking command value S3 by bringing the current speed command value, which is the previous tracking command value S3, closer to the target speed command value S2 by a value determined based on the difference between the current speed command value and the target speed command value S2 at each predetermined tracking process interval until the current speed command value S3 reaches the target speed command value S2.

In Figures 3A and 3B, the vertical axis represents the rotation speed at the speed command value, and the horizontal axis represents the time elapsed during tracking processing of the speed command value. In the example shown in Figure 3A, the predetermined tracking processing interval is a fixed time, and the preset value is, for example, 1000 rpm. In this case, it can be seen that the tracking command value S3 changes linearly.

In the example shown in Figure 3B, as the target speed command value S2 is approached (as the difference between the current speed command value and the target speed command value S2 becomes smaller), the predetermined tracking processing interval becomes smaller, and the value determined in accordance with the difference between the current speed command value and the target speed command value S2 (the value that brings the current speed command value closer to the target speed command value S2) becomes larger. In this case, it can be seen that the tracking command value S3 changes in a curved line.

In this way, in the tracking process of the first embodiment, either the rotation speed in the speed command value or the tracking process interval may be changed, as shown in Figure 3A, or both the rotation speed in the speed command value and the tracking process interval may be changed, as shown in Figure 3B. By changing both the rotation speed and the tracking process interval, the degree of change in the rotation speed in the tracking process can be adjusted.

Next, we will explain the flow of the tracking process performed by the speed command tracking processing unit 221 of the motor drive control device 20 described above.

Figure 4 is a flowchart of the tracking process performed by the speed command tracking processing unit 221 in the first embodiment.

First, the speed command tracking processing unit 221 acquires the target speed command value S2 (step S101), compares the acquired target speed command value S2 with the previous tracking command value S3, which is the current speed command value, and determines whether the acquired target speed command value S2 is greater than the current speed command value (the previous tracking command value S3) (step S102).

In step S102, if the speed command tracking processing unit 221 determines that the acquired target speed command value S2 is not greater than the current speed command value (previous tracking command value S3) (step S102: NO), it further determines whether the acquired target speed command value S2 is smaller than the current speed command value (previous tracking command value S3) (step S103).

In step S103, if the speed command tracking processing unit 221 determines that the acquired target speed command value S2 is not smaller than the current speed command value (previous tracking command value S3) (step S103: NO), the acquired target speed command value S2 is equal to the current speed command value (previous tracking command value S3), and the processing ends.

On the other hand, if the speed command tracking processing unit 221 determines in step S102 that the acquired target speed command value S2 is greater than the current speed command value (step S102: YES), it sets the addition unit value and addition interval by referring to the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230 (step S104).

The speed command tracking processing unit 221 calculates the rotation speed and tracking processing interval based on the addition unit value and addition interval set in step S104 (step S105). Specifically, the rotation speed and tracking processing interval specified by the current tracking command value S3 are increased by the addition unit value, and the tracking processing interval is increased by the addition interval.

The speed command follow-up processing unit 221 changes the follow-up command value S3 so as to specify the rotation speed and follow-up processing interval calculated in step S105 (step S106).
On the other hand, in step S103, if the speed command tracking processing unit 221 determines that the acquired target speed command value S2 is smaller than the current speed command value (step S103: YES), it sets the subtraction unit value and subtraction interval by referring to the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230 (step S107).

The speed command tracking processing unit 221 calculates the rotation speed and tracking processing interval based on the subtraction unit value and subtraction interval set in step S107 (step S108). Specifically, the rotation speed is reduced by the subtraction unit value relative to the rotation speed and tracking processing interval specified by the current tracking command value S3, and the tracking processing interval is reduced by the subtraction interval.

The speed command tracking processing unit 221 changes the tracking command value S3 to specify the rotation speed and tracking processing interval calculated in step S108 (step S106).

When the speed command tracking processing unit 221 completes processing of step S106, it returns to processing of step S101.

The drive control signal generator 222 generates a drive control signal Sd based on the tracking command value S3 changed by the above tracking process, thereby gradually changing the rotation speed of the motor 10 until it reaches the target rotation speed.

Figure 5 is a diagram illustrating an example of signal waveforms between each component within the control unit 200.

Figure 5 shows the target speed command value S2 received by the control unit 200 as the PWM signal Sc1 when the duty is constant, when the duty is variable, and when noise is superimposed.

When the PWM signal Sc1 has a constant duty, the duty comparison unit 211 outputs a duty ratio signal S1 indicating a constant duty ratio of 40%, for example, to the speed command conversion unit 212, as shown in the graph on the left side of Figure 5, and the speed command conversion unit 212 outputs a constant target speed command value S2 corresponding to the constant duty ratio of 40%, for example, 16,000 rpm, to the speed command tracking processing unit 221. In this case, the speed command tracking processing unit 221 continues to output 16,000 rpm as the constant tracking command value S3, which is the same as the target speed command value S2 of 16,000 rpm.

When the duty of PWM signal Sc1 changes, the duty comparison unit 211 outputs a duty ratio signal S1 indicating that the duty ratio has changed, for example, from 40% to 80%, to the speed command conversion unit 212, as shown in the center graph of Figure 5. The speed command conversion unit 212 outputs, for example, 32,000 rpm as the target speed command value S2 corresponding to the duty ratio at the time the duty ratio changes from 40% to 80%, to the speed command tracking processing unit 221. In this case, the speed command tracking processing unit 221 outputs, as the tracking command value S3, a rotational speed of (16,000 + α) rpm (α is a value that gradually increases to 16,000) set so that the change amount of 16,000 rpm in the target speed command value S2 relative to the current speed command value of 16,000 rpm changes by a predetermined ratio over a predetermined number of times.

When noise is superimposed on the PWM signal Sc1, the duty comparison unit 211 outputs a duty ratio signal S1 to the speed command conversion unit 212, indicating that the duty ratio has changed, for example, from 40% to 0%, as shown in the graph on the right side of Figure 5. The speed command conversion unit 212 outputs 0 rpm to the speed command tracking processing unit 221 as the target speed command value S2 corresponding to the duty ratio when the duty ratio changes from 40% to 0%. In this case, the speed command tracking processing unit 221 outputs a rotational speed (16,000 + α) rpm (α is a value that gradually decreases to 0) as the tracking command value S3, which is set so that the change in the target speed command value S2 from the current speed command value of 16,000 rpm, 16,000 rpm, changes at a predetermined rate over a predetermined number of times. However, because this change is due to noise, the value returns to its original value after a temporary change. Although the rotation speed changes temporarily, it does not change suddenly, so the rotation of the motor 10 does not become unstable. In other words, the tracking process of the first embodiment allows the motor 10 to maintain stable rotational operation.

The maintenance of stable rotational operation of the motor 10 using the tracking process of the first embodiment will be further explained in comparison with conventional moving average processing.

FIG. 6A is a diagram showing a comparison between a command value obtained by the conventional moving average process and a command value obtained by the follow-up process according to the first embodiment when a speed command value is changed.
FIG. 6B is a graph visually illustrating the change in the command value of FIG. 6A.

FIG. 7A is a diagram showing a comparison between command values obtained by conventional moving average processing and command values obtained by the tracking processing of the first embodiment when noise is superimposed.
FIG. 7B is a graph visually illustrating the change in the command value of FIG. 7A.

In Figures 6A to 7B, the speed command tracking processing unit 221, as in Figure 3A, performs tracking processing to set a new tracking command value S3 by bringing the current speed command value, which is the previous tracking command value S3, closer to the target speed command value S2 by a preset value at regular tracking processing intervals until the current speed command value reaches the target speed command value S2. In this example, the preset value (resolution) in the tracking processing is 500 rpm, and the moving average used is a value obtained by moving average processing over four steps.

(1) When the Speed Command Value is Changed In FIG. 6A, consider the case where the target speed command value S2 changes from a stopped state (target speed command value S2 is 0 rpm) to 10,000 rpm. In the first step after the change in target speed command value S2, the follow-up command value S3 obtained by the follow-up process is 500 rpm, but the moving average value obtained by the moving average process is 2,500 rpm because it is the average value of the current command rotational speed Va0 and the command rotational speeds up to three steps ago (command rotational speed Va-3 three steps ago, command rotational speed Va-2 two steps ago, and command rotational speed Va-1 one step ago). Similarly, in the second step, the follow-up command value S3 is 1,000 rpm, but the moving average value is 5,000 rpm. As a result, in the case of moving average processing, the moving average value becomes 10,000 rpm at the fourth step, but in the case of follow-up processing, the follow-up command value S3 becomes 10,000 rpm at the 20th step.

As shown in FIG. 6B, the moving average value reaches the target speed command value S2 in four steps, and the following command value S3 also reaches the target speed command value S2 in 20 steps.
Furthermore, when the target speed command value S2 changes to 5000 rpm at the 21st step, in the case of moving average processing, the moving average value becomes 5000 rpm at the 24th step, whereas in the case of following processing, the following command value S3 becomes 5000 rpm at the 30th step.
That is, it can be seen that the target speed command value S2 can be reached by either the moving average process or the following process. As described above, the following process according to the present embodiment causes a delay in reaching the target speed command value S2 compared to the conventional moving average process, but the delay is negligible.

(2) When Noise is Superimposed As shown in FIG. 7A , consider the case where noise is superimposed when the target speed command value S2 is 10,000 rpm, causing the target speed command value S2 to temporarily change to 0 rpm (from step N4 to step N9). In the first step (step N4) after the change in the target speed command value S2, the tracking command value S3 obtained by the tracking process is 9,500 rpm, but the moving average value obtained by the moving average process is 7,500 rpm. Similarly, in the second step (step N5), the tracking command value S3 is 9,000 rpm, but the moving average value is 5,000 rpm. As a result, in the case of moving average process, the moving average value becomes 0 rpm in the fourth step (step N7). However, in the case of tracking process, even in the sixth step (step N9), which is the last step affected by noise, the tracking command value S3 remains 7,000 rpm, not 0 rpm.

As shown in Figure 7B, in the case of moving average processing, the moving average value is completely affected by noise in four steps (N7 step), including the step (N4 step) in which the target speed command value S2 changes, and reaches 0 rpm. Once the influence disappears, it returns to its original value in four steps, which shows that the rotational operation of the motor 10 is unstable. On the other hand, in the case of tracking processing, the noise only slightly affects the tracking command value S3, and the noise does not cause a large change, so it shows that the stable rotational operation of the motor 10 can be maintained.

The motor drive control device 20 of the first embodiment described above makes it possible to maintain stable rotational operation of the motor 10 even if the external drive command changes suddenly.

Second Embodiment
Next, a motor drive control device 20A according to a second embodiment will be described.

FIG. 8 is a diagram showing a specific example of the configuration of a motor unit 1A equipped with a motor drive control device 20A according to the second embodiment.
As shown in FIG. 8, the motor drive control device 20A includes a pulse output circuit (an example of an operation command signal output circuit) 100A, a control unit 200A, and a motor drive unit 300.
FIG. 9 is a block diagram showing the internal configuration of a control unit 200A of a motor drive control device 20A according to the second embodiment.

In the motor drive control device 20 of the first embodiment, a PWM signal PWM is input from the upper device 2 as a drive command signal indicating a target speed for driving the motor 10. However, in the motor drive control device 20A of the second embodiment, a pulse signal (an example of a drive command signal) STMP and a signal indicating the rotation direction (hereinafter also referred to as the "rotation direction signal CW/CCW") are input from the upper device 2A as a drive command signal including a drive command indicating a target value for driving the motor 10 as a target rotation position. In the motor drive control device 20 of the first embodiment, the PWM output circuit 100 generates a PWM signal (an example of an operation command signal) Sc1 based on the PWM signal PWM from the upper device 2, and the command value conversion processing unit 210 converts this to a target speed command value S2. In contrast, the motor drive control device 20A of the second embodiment differs in that it includes a pulse output circuit (an example of an operation command signal output circuit) 100A that inputs the pulse signal STMP and generates and outputs a pulse signal (an example of an operation command signal) Sc2, and a command value conversion processing unit 210A that converts the input pulse signal Sc2 and rotation direction signal CW/CCW into a target position command value S2a. The rest of the configuration is the same as that of the motor drive control device 20 of the first embodiment, so a description thereof will be omitted.

The control unit 200A is a circuit for comprehensively controlling the operation of the motor drive control device 20A. In the second embodiment, the control unit 200A is a program processing device having a configuration in which a timer with input capture function, ROM, RAM, a clock generation circuit, a processor (such as a CPU), and an input/output I/F circuit are connected to each other via a bus or dedicated line, as shown in FIG. 8. For example, the control unit 200A is a microcontroller (MCU: Micro Controller Unit). The control unit 200A may also include various storage devices such as flash memory, a timer as a counter, an A/D conversion circuit, a D/A conversion circuit, and other peripheral circuits.

The control unit 200A and the motor drive unit 300 may be packaged as a single semiconductor integrated circuit (IC), or may be packaged as separate integrated circuits mounted on a circuit board and electrically connected to each other on the circuit board.

The pulse output circuit 100A is a circuit that generates a pulse signal Sc2 based on a pulse signal STMP input from an external device (e.g., a higher-level device 2A) and inputs the pulse signal Sc2 to the control unit 200A. The pulse output circuit 100A can be configured, for example, by a damping resistor and a pull-down resistor.
Control unit 200A has a basic function of controlling the energization of motor 10 by generating a drive control signal Sd and providing it to motor drive unit 300. Specifically, based on the input operation command signals, pulse signal Sc2 and rotation direction signal CW/CCW, control unit 200A generates drive control signal Sd and provides it to motor drive unit 300 so that motor 10 is in the operating state specified by the operation command (rotational position command in this embodiment) included in pulse signal Sc2. In the second embodiment, the number of steps of motor 10 is specified by pulse signal Sc2, and the rotation direction signal CW/CCW is used to specify the rotation direction of motor 10, thereby specifying a target rotation position of motor 10.

In addition to the above basic functions, the control unit 200A also has a tracking processing function that, when a target command value specified in an operation command included in the pulse signal Sc2 changes, generates a drive control signal Sd corresponding to a command value that has been tracked so that it changes at a predetermined rate of change in the target command value over a predetermined number of times.

As shown in FIG. 9, the control unit 200A has functional units for realizing the above-mentioned functions, such as a command value conversion processing unit 210A having an interrupt circuit unit 211A, a direction determination unit 212A, and a counter 213A, a tracking drive control signal generation unit 220A having a position command tracking processing unit 221A and a drive control signal generation unit 222A, and a memory unit 230A.

The above-mentioned functional units of the control unit 200A are realized, for example, by program processing of the MCU that serves as the control unit 200A. Specifically, the above-mentioned functional units are realized by a processor that constitutes the MCU that serves as the control unit 200A performing various calculations in accordance with programs stored in memory and controlling the various peripheral circuits that make up the MCU.

The command value conversion processing unit 210A receives, for example, the pulse signal Sc2 and rotation direction signal CW/CCW input to the pulse output circuit 100A. The pulse signal Sc2 and rotation direction signal CW/CCW function as operation command signals and indicate target values related to the operation of the motor 10. The pulse signal Sc2 and rotation direction signal CW/CCW include, for example, a signal indicating the target rotation position of the motor 10.

The command value conversion processing unit 210A analyzes the number of steps and rotation direction specified by the operation command signal (pulse signal Sc2 and rotation direction signal CW/CCW) and outputs information on the rotation position corresponding to the number of steps and rotation direction as a target position command value S2a. Specifically, for example, in the command value conversion processing unit 210A, the interrupt circuit unit 211A outputs the number of steps S1a required to reach the target position analyzed from the pulse signal Sc2 to the counter 213A, and the direction determination unit 212A outputs a rotation direction indication signal S1b indicating whether the rotation direction is forward CW or reverse CCW from the rotation direction signal CW/CCW to the counter 213A. In the command value conversion processing unit 210A, the counter 213A adds the number of steps S1a to its count value when the rotation direction is forward CW, and subtracts the number of steps S1a from its count value when the rotation direction is reverse CCW. Counter 213A outputs the calculated count value as the target position command value S2a.

When the target position command value S2a acquired from the command value conversion processing unit 210A changes, the follow-up drive control signal generation unit 220A generates a drive control signal Sd based on a follow-up command value S3a, which is a command value that has been subjected to follow-up processing so that the value changes a predetermined number of times at a predetermined rate of the amount of change in the acquired target position command value S2a. Specifically, the position command follow-up processing unit 221A calculates the follow-up command value S3a through follow-up processing, and the drive control signal generation unit 222A calculates the operation amount of the motor 10 so that the rotational position of the motor 10 matches the rotational position specified by the follow-up command value S3a, and generates a drive control signal Sd based on the calculated operation amount. Details of the follow-up processing, which is one of the functions of the follow-up drive control signal generation unit 220A, will be described later.

Memory unit 230A stores the addition/subtraction unit value and addition/subtraction interval referenced in the tracking process. The addition/subtraction unit value is the size of the number of steps indicating the position to be added or subtracted as a predetermined percentage of the change in the target position command value S2a, and is set according to the specifications of motor 10 and motor drive unit 300. The addition/subtraction interval is the time interval (hereinafter also referred to as the "tracking process interval") at which a predetermined percentage of the change in the target position command value S2a is changed (added or subtracted), and is set according to the specifications of motor 10 and motor drive unit 300.

When the target position command value S2a acquired from the command value conversion processing unit 210A changes, the position command tracking processing unit 221A performs tracking processing by referencing the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230A as necessary, to calculate a tracking command value S3a, and outputs this to the drive control signal generation unit 222A. When the target position command value S2a acquired from the command value conversion processing unit 210A does not change, the position command tracking processing unit 221A outputs the same position command value as before as the tracking command value S3a to the drive control signal generation unit 222A.

The drive control signal generation unit 222A calculates the operation amount of the motor 10 based on the rotational position and the operation interval specified by the operation command value S3a received from the position command operation processing unit 221A, generates a PWM signal having a PWM period and an ON period determined based on the calculated operation amount as the drive control signal Sd, and outputs it to the motor drive unit 300.

Next, we will explain the flow of the tracking process performed by the position command tracking processing unit 221A of the motor drive control device 20A described above.

FIG. 10 is a flowchart of the tracking process by the position command tracking processor 221A according to the second embodiment.
First, the position command tracking processing unit 221A acquires the target position command value S2a (step S201), compares the acquired target position command value S2a with the previous tracking command value S3a, which is the current position command value, and determines whether the acquired target position command value S2a is greater than the current position command value (the previous tracking command value S3a) (step S202).

In step S202, if the position command tracking processing unit 221A determines that the acquired target position command value S2a is not greater than the current position command value (previous tracking command value S3a) (step S202: NO), it further determines whether the acquired target position command value S2a is smaller than the current position command value (previous tracking command value S3a) (step S203).

In step S203, if the position command tracking processing unit 221A determines that the acquired target position command value S2a is not smaller than the current position command value (previous tracking command value S3a) (step S203: NO), the acquired target position command value S2a is equal to the current position command value (previous tracking command value S3a), and the processing ends.

On the other hand, if the position command tracking processing unit 221A determines in step S202 that the acquired target position command value S2a is greater than the current position command value (step S202: YES), it sets the addition unit value and addition interval by referencing the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230A (step S204).

The position command tracking processing unit 221A calculates the rotation position and tracking processing interval based on the addition unit value and addition interval set in step S204 (step S205). Specifically, the rotation position is increased by the addition unit value relative to the rotation position and tracking processing interval specified by the current tracking command value S3a, and the tracking processing interval is increased by the addition interval.

The position command follow-up processing unit 221A changes the follow-up command value S3a so as to specify the rotational position and follow-up processing interval calculated in step S205 (step S206).
On the other hand, in step S203, if the position command tracking processing unit 221A determines that the acquired target position command value S2a is smaller than the current position command value (step S203: YES), it sets the subtraction unit value and subtraction interval by referring to the addition/subtraction unit value and addition/subtraction interval stored in the memory unit 230A (step S207).

The position command tracking processing unit 221A calculates the rotation position and tracking processing interval based on the subtraction unit value and subtraction interval set in step S207 (step S208). Specifically, the rotation position is returned by the subtraction unit value relative to the rotation position and tracking processing interval specified by the current tracking command value S3a, and the tracking processing interval is reduced by the subtraction interval.

The position command tracking processing unit 221A changes the tracking command value S3a to specify the rotational position and tracking processing interval calculated in step S208 (step S206).

When the processing of step S206 is completed, the position command tracking processing unit 221A returns to step S201.

The drive control signal generator 222A generates a drive control signal Sd based on the tracking command value S3a changed by the above tracking process, thereby gradually changing the rotational position of the motor 10 until it reaches the target rotational position.

Here, we will further explain the method by which the position command tracking processing unit 221A calculates the tracking command value S3a through tracking processing, comparing it with a conventional motor drive control device that does not perform tracking processing.

Figure 11A shows an example of the change in rotational position (current position) when the target position command value is changed in a conventional motor drive control device.

In conventional motor drive control devices, the drive control signal generation unit generates a drive control signal based on a target rotational position command value, and the motor drive unit drives the motor. However, for example, when printing thick paper such as a passport on a printer or copier, the motor does not rotate immediately due to the heavy load. For this reason, it begins to rotate only after the motor drive output of the motor drive unit increases. Because the motor rotates with a high drive output, as a result, as shown in Figure 11A, it rotates beyond the target position command value, and it is therefore necessary to rotate in the reverse direction to return to the position specified by the target position command value.

Figure 11B is a diagram showing an example of the change in the tracking command value S3a and the change in the rotational position (current position) when the target position command value S2a is changed in the motor drive control device 20A of the second embodiment.

The position command tracking processing unit 221A executes tracking processing when the target position command value S2a acquired from the command value conversion processing unit 210A changes. The tracking processing is a process in which, even when the target position command value S2a changes, the amount of change in the target position command value S2a is not changed all at once, but rather a tracking command value S3a that changes over a predetermined number of times at a predetermined rate of the amount of change in the acquired target position command value S2a is output as a new tracking command value S3a to the drive control signal generation unit 222A.

Specifically, if there is a difference between the current position command value, which is the previous tracking command value S3a, and the newly acquired command value, which is the target position command value S2a, the position command tracking processing unit 221A determines that the acquired target position command value S2a has changed and executes tracking processing.

Specifically, as part of the tracking process, the position command tracking processing unit 221A does not change the amount of change in the target position command value S2a all at once, but instead outputs a new tracking command value S3a, which is a value that changes over a predetermined number of times at a predetermined rate relative to the amount of change in the acquired target position command value S2a, to the drive control signal generation unit 222A.

In the tracking process shown in Figure 11B, the position command tracking processing unit 221A sets the new tracking command value S3a by bringing the current position command value, which is the previous tracking command value S3a, closer to the target position command value S2a by a preset value at each specified tracking process interval until it reaches the target position command value S2a. As shown in Figure 11B, this tracking command value S3a changes the rotational position of the motor 10 more slowly than the target position command value S2a, so it can be seen that it can be stopped near the target position command value S2a.

As another tracking process, the position command tracking processing unit 221A may set as a new tracking command value S3a a value obtained by bringing the current position command value, which is the previous tracking command value S3a, closer to the target position command value S2a by a value determined based on the difference between the current position command value and the target position command value S2a at each predetermined tracking processing interval until the current position command value S3a reaches the target position command value S2a.

Furthermore, as another tracking process, the position command tracking processing unit 221A may set the predetermined tracking processing interval to a smaller value as the current position command value approaches the target position command value S2a (as the difference between the current position command value and the target position command value S2a becomes smaller), and set the value determined in accordance with the difference between the current position command value and the target position command value S2a (the value that brings the current position command value closer to the target position command value S2a) to a larger value. In this case, the tracking command value S3a will change in a curved manner.

In this way, in the tracking process of the second embodiment, either the rotational speed or the tracking process interval in the target position command value S2a may be changed, or both the rotational position and the tracking process interval in the target position command value S2a may be changed. By changing both the rotational position and the tracking process interval, the degree of change in the rotational position in the tracking process can be adjusted.

The motor drive control device 20A of the second embodiment described above makes it possible to maintain stable rotational operation of the motor 10 even if the external drive command changes suddenly.

<<Extension of Embodiment>>
The invention made by the inventor has been specifically described above based on an embodiment, but it goes without saying that the invention is not limited thereto and can be modified in various ways without departing from the spirit of the invention.

For example, in the above embodiment, the motor 10 is described as a brushless DC motor having three-phase (U-phase, V-phase, and W-phase) coils (windings) Lu, Lv, and Lw, but the number of phases and type of motor are not limited to these.

Furthermore, while the first embodiment uses a PWM signal as the signal input from the higher-level device and the second embodiment uses a pulse signal as an example, this is not limiting. The signal input from the higher-level device may also be, for example, a level-changing signal. In the case of a level-changing signal, a level-changing signal output circuit having an AD converter can be used instead of a PWM output circuit or pulse output circuit.

Although the motor drive control device 20 described above does not have a feedback control function, it is possible to provide the motor drive control device 20 with this function by, for example, providing a position detector that detects the rotational position of the motor 10 and outputs the result as a position detection signal. In this case, the drive control signal generator 222 may calculate the actual rotational speed of the motor 10 based on the position detection signal, and then perform control calculation processing such as PID (Proportional-Integral-Differential) to calculate the operation amount (PWM period and on-period) of the motor 10 so that the calculated actual rotational speed matches the rotational speed specified by the tracking command value S3. In this case, the position detector may be, for example, a Hall element, a Hall IC, an encoder, or a resolver.

Furthermore, the above-described flowcharts are merely examples and are not intended to be limiting. For example, other processes may be inserted between each step, or the processes may be parallelized.

1, 1A...motor unit, 2, 2A...host device, 10...motor, 20, 20A...motor drive control device, 100...PWM output circuit (an example of an operation command signal output circuit), 100A...pulse output circuit (an example of an operation command signal output circuit), 200, 200A...control unit, 210, 210A...command value conversion processing unit, 211...duty comparison unit, 212...speed command conversion unit, 211A...interrupt circuit unit, 212A...direction determination unit, 213A...counter, 220, 220A...following drive control signal generation unit, 221...speed command following processing unit, 221 A...position command tracking processing unit, 222, 222A...drive control signal generation unit, 230...storage unit, 300...motor drive unit, S1...duty ratio signal, S1a...step count, S1b...rotation direction command signal, S2...target speed command value, S2a...target position command value, S3, S3a...tracking command value, PWM...PWM signal (an example of a drive command signal), STMP...pulse signal (an example of a drive command signal), Sc1...PWM signal (an example of an operation command signal), Sc2...pulse signal (an example of an operation command signal), Sd...drive control signal, CW/CCW...rotation direction signal

Claims (5)

a motor driving unit that applies a voltage to a coil of the motor based on a drive control signal for controlling the driving of the motor, thereby driving the motor;
a control unit that generates the drive control signal based on an operation command signal for the motor and outputs the drive control signal to the motor drive unit;
an operation command signal output circuit that receives a drive command signal from an external device and outputs the operation command signal to the control unit;
The control unit
a command value conversion processing unit that converts the operation command included in the operation command signal into a target command value;
a follow-up drive control signal generation unit that acquires the target command value from the command value conversion processing unit, and when the acquired target command value changes, generates the drive control signal based on a follow-up command value that is a command value that has been subjected to follow-up processing so as to change a predetermined number of times at a predetermined rate of change in the acquired target command value ,
The follow-up drive control signal generation unit
a speed command tracking processing unit that determines that the acquired target speed command value has changed when there is a difference between a current speed command value that is a previous tracking command value and a target speed command value that is a newly acquired target command value, and executes tracking processing to set a value that approaches the current speed command value to the target speed command value by a value determined according to the difference at each predetermined tracking processing interval until the current speed command value reaches the target speed command value;
a drive control signal generation unit that generates the drive control signal based on the new tracking command value;
the speed command tracking processing unit sets the predetermined tracking processing interval to a smaller value as the difference becomes smaller, and sets the value that brings the current speed command value closer to the target speed command value to a larger value .
Motor drive control device. a motor driving unit that applies a voltage to a coil of the motor based on a drive control signal for controlling the driving of the motor, thereby driving the motor;
a control unit that generates the drive control signal based on an operation command signal for the motor and outputs the drive control signal to the motor drive unit;
an operation command signal output circuit that receives a drive command signal from an external device and outputs the operation command signal to the control unit;
The control unit
a command value conversion processing unit that converts the operation command included in the operation command signal into a target command value;
a follow-up drive control signal generation unit that acquires the target command value from the command value conversion processing unit, and when the acquired target command value changes, generates the drive control signal based on a follow-up command value that is a command value that has been subjected to follow-up processing so as to change a predetermined number of times at a predetermined rate of change in the acquired target command value,
The follow-up drive control signal generation unit
a position command tracking processing unit that determines that the acquired target position command value has changed when there is a difference between a current position command value that is a previous tracking command value and a target position command value that is a newly acquired target command value, and executes tracking processing to set a new tracking command value as a value that brings the current position command value closer to the target position command value by a value determined according to the difference at each predetermined tracking processing interval until the current position command value reaches the target position command value;
a drive control signal generation unit that generates the drive control signal based on the new tracking command value;
the position command tracking processing unit sets the predetermined tracking processing interval to a smaller value as the difference becomes smaller, and sets the value that brings the current position command value closer to the target position command value to a larger value .
Motor drive control device. The motor drive control device according to claim 1 or 2 ;
A motor unit comprising the motor. A motor drive control method using a motor drive control device including: a motor drive unit that applies a voltage to a coil of the motor based on a drive control signal for controlling drive of the motor to drive the motor; a control unit that generates the drive control signal based on an operation command signal of the motor and outputs the drive control signal to the motor drive unit; and an operation command signal output circuit that receives a drive command signal from an external device and outputs the operation command signal to the control unit,
The control unit
a command value conversion processing step of converting the operation command included in the operation command signal into a target command value;
a follow-up drive control signal generating step of generating the drive control signal based on a follow-up command value which is a command value that has been subjected to follow-up processing so as to change a predetermined number of times at a predetermined rate of change in the acquired target command value when the target command value converted in the command value conversion processing step has changed ,
The follow-up drive control signal generating step includes:
a speed command tracking processing substep of determining that the acquired target speed command value has changed when there is a difference between a current speed command value that is a previous tracking command value and a target speed command value that is a newly acquired target command value, and executing tracking processing to set a value that approaches the current speed command value to the target speed command value by a value determined according to the difference at each predetermined tracking processing interval until the current speed command value reaches the target speed command value;
a drive control signal generating substep of generating the drive control signal based on the new tracking command value;
the speed command tracking substep sets the predetermined tracking processing interval to a smaller value as the difference becomes smaller, and sets a value that brings the current speed command value closer to the target speed command value to a larger value.
Motor drive control method. A motor drive control method using a motor drive control device including: a motor drive unit that applies a voltage to a coil of the motor based on a drive control signal for controlling drive of the motor to drive the motor; a control unit that generates the drive control signal based on an operation command signal of the motor and outputs the drive control signal to the motor drive unit; and an operation command signal output circuit that receives a drive command signal from an external device and outputs the operation command signal to the control unit,
The control unit
a command value conversion processing step of converting the operation command included in the operation command signal into a target command value;
a follow-up drive control signal generating step of generating the drive control signal based on a follow-up command value which is a command value that has been subjected to follow-up processing so as to change a predetermined number of times at a predetermined rate of change in the acquired target command value when the target command value converted in the command value conversion processing step has changed,
The follow-up drive control signal generating step includes:
a position command tracking processing substep of determining that the acquired target position command value has changed when there is a difference between a current position command value that is the previous tracking command value and a target position command value that is a newly acquired target command value, and executing a tracking processing to set a new tracking command value as a value that brings the current position command value closer to the target position command value by a value determined according to the difference at every predetermined tracking processing interval until the current position command value reaches the target position command value;
a drive control signal generating substep of generating the drive control signal based on the new tracking command value;
the position command tracking processing substep sets the predetermined tracking processing interval to a smaller value as the difference becomes smaller, and sets a value that brings the current position command value closer to the target position command value to a larger value.
Motor drive control method.