JP2022115007A - Motor control device, motor control system, and motor control method - Google Patents

Abstract

To provide a motor control device capable of stabilizing rotation of a motor even if an encoder pulse temporarily shifts upward.SOLUTION: A motor control device has a position signal counter (41), a frequency signal generation unit (42), and a speed determination unit (43) for determining a rotation speed of a motor calculated based on a count number when the count number of the position signal counter (41) is equal to or more than a predetermined value as a rotation speed of the motor, and determining a smaller speed of the rotation speed of the motor determined based on the position signal counter and a speed upper limit value as the speed of the motor when the position signal counter (41) does not count. The speed determination unit (43) determines the speed upper limit value so that the rotation speed of the motor determined may be smaller according to a continuous frequency of a low count period that is a period when the position signal counter (41) does not count in the predetermined period.SELECTED DRAWING: Figure 2

Description

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

Japanese Unexamined Patent Application Publication No. 2002-200002 describes a motor control device that monitors motor rotation by an encoder to control motor speed and drive amount. The motor controller detects pulses indicative of motor rotation by single-sided edges of the pulse signal output by the sensor during high speed control. The motor controller detects pulses indicative of motor rotation by both edges of the pulse signal output by the sensor during low speed control. Furthermore, the motor control device controls the motor speed and drive amount by performing interrupt processing based on the detected pulses.

JP-A-9-266686

In the motor control device, the rotational speed of the motor is determined for each periodic interrupt interval that occurs at predetermined time intervals, and speed control can be executed based on the determined rotational speed of the motor. Methods of determining the speed include a method of calculating the rotational speed of the motor at each periodic interrupt interval and a method of calculating the rotational speed of the motor only in a predetermined case. In the method of calculating the rotation speed of the motor only in a predetermined case, the motor control device calculates the rotation speed of the motor, for example, when encoder pulses are counted in the periodic interrupt interval. If not, then at the next periodic interrupt interval, the motor controller uses the previous motor rotation speed.

However, if the previous rotation speed of the motor is also used in the next periodic interrupt interval, if the encoder pulse temporarily overshoots due to vibration or the like, the motor controller will detect that the speed is much higher than the actual rotation speed of the motor. may be misunderstood. As a result of misrecognition, speed control may become unstable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems. It is to provide a system and a motor control method.

In order to solve the above problems, the motor control device described in one embodiment includes a position signal counter that counts the number of times a position signal is received each time the motor rotates by a predetermined angle, and a and a periodic signal generating unit that generates a periodic signal at the current timing of generating the periodic signal when the count number of the position signal counter in the predetermined period is equal to or greater than a predetermined value. If it is determined as velocity and the position signal counter does not count in the predetermined period, the time from the time when the position signal counter last received the position signal to the time when the position signal was received immediately before the last time. The smaller one of the motor rotation speed determined based on the time until the current periodic signal generation timing and the speed upper limit value that is the upper limit of the speed that can be determined as the speed at the current periodic signal generation timing. and a drive signal generator for generating a drive signal for driving the motor according to the determined speed, wherein the speed determination unit determines the rotation speed of the motor to be determined However, the upper speed limit value is determined so that the low count period, which is the period during which the position signal counter does not count in the predetermined period, decreases according to the number of consecutive times.

INDUSTRIAL APPLICABILITY According to the motor control device, motor control system, and motor control method of the present invention, it is possible to stabilize the rotation of the motor even if the rotation speed of the motor temporarily increases.

1 is a schematic configuration diagram showing an example of a motor control system according to a first embodiment; FIG. 2 is a schematic configuration diagram showing a configuration example of a control unit 4 of a motor control device 3; FIG. 4 is a flow chart showing an example of encoder interrupt operation in the operation of the motor control system; 5 is a flow chart showing an example of periodic interrupt operation in operation of the motor control system; FIG. 4 is a diagram for explaining a signal output from an encoder; FIG. FIG. 5 is a diagram showing an example of controlling the rotation speed of a motor when vibration and rotation unevenness occur; FIG. 4 is a diagram showing the relationship between encoder interrupts and periodic interrupts and speed;

1. Outline of Embodiment First, an outline of a representative embodiment of the invention disclosed in the present application will be described. In the following description, as an example, reference numerals on the drawings corresponding to constituent elements of the invention are described with parentheses.

[1] A motor control device according to a representative embodiment of the present invention includes a position signal counter (41) for counting the number of times a position signal is received each time the motor rotates by a predetermined angle, and a periodic signal generator (42) for generating a periodic signal every time, and when the count number of the position signal counter (41) in the predetermined period is equal to or greater than a predetermined value, the rotation of the motor calculated based on the count number. The speed is determined as the rotational speed of the motor at the current period signal generation timing, and if the position signal counter (41) does not count in the predetermined period, the position signal counter finally outputs the position signal. Motor rotation speed determined based on the time from the time when the position signal was received until the time when the position signal was received immediately before the last time, and the speed upper limit value that is the upper limit of the speed that can be determined as the speed at the timing of generating the current periodic signal and a speed determination unit (43) for determining the smaller speed of the motor as the rotation speed of the motor at the current timing of generating the periodic signal, and a drive for driving the motor according to the determined rotation speed of the motor a drive signal generator (50) for generating a signal, and the speed determination unit (43) determines whether the rotational speed of the motor to be determined is not counted by the position signal counter (41) in the predetermined period. The speed upper limit value is determined so that the low count period, which is the period of the low count, becomes smaller according to the number of consecutive times.

[2] In the motor control device described in [1] above, the periodic signal generator may generate the periodic signal at the same time intervals regardless of the rotation speed of the motor.

[3] In the motor control device described in [1] or [2] above, the speed determining unit, when the number of counts of the position signal counter in the predetermined cycle is equal to or greater than a predetermined value, controls the speed of the motor. Based on the number of times the position signal is generated per rotation, the predetermined period, and the number of counts of the position signal counter in the predetermined period, the rotational speed of the motor at the current period signal generation timing is determined. may be determined.

[4] The motor control device according to any one of [1] to [3] above, wherein the speed determination unit determines the number of times the position signal is generated per rotation of the motor; The upper speed limit is determined based on a predetermined cycle, the number of counts of the position signal counter in the predetermined cycle, and the number of consecutive low count cycles.

[5] A motor control system according to a representative embodiment of the present invention includes the motor control device according to any one of [1] to [4] above, and a drive signal output from the motor control device. and an encoder for detecting the rotational position of the motor.

[6] A motor control method according to a representative embodiment of the present invention includes a position signal counting step for counting the number of times a position signal is received each time the motor rotates by a predetermined angle; determining the rotational speed of the motor calculated based on the number of counts of the periodic signal generating step for generating the periodic signal and the position signal counting step in the predetermined period as the rotational speed of the motor at the current timing of generating the periodic signal; If the position signal count step in the predetermined cycle is not counted, the position signal counter is used during the time from the time when the position signal was last received to the time when the position signal was received immediately before the last time. The motor rotation speed at the current periodic signal generation timing is the smaller one of the motor rotation speed determined based on the current frequency and the speed upper limit value that is the upper limit of the speed that can be determined as the speed at the current periodic signal generation timing. and a drive signal generation step of generating a drive signal for driving the motor so as to achieve the determined rotation speed of the motor, wherein the speed determination step includes: is determined such that the rotational speed of is decreased according to the number of consecutive low count cycles, which are cycles in which the position signal count steps are not counted in the predetermined cycle.

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, constituent elements common to each embodiment are denoted by the same reference numerals, and repeated descriptions are omitted.

(First embodiment)
First, the motor control device, motor control system, and motor control method of the first embodiment will be described.

FIG. 1 is a schematic configuration diagram showing an example of the motor control system of the first embodiment. The motor control system of this embodiment controls the driving of the motor. As shown in FIG. 1, the motor control system of this embodiment includes a motor 1, an encoder 2 that detects the rotation angle of the motor 1, and a motor control device 3 that receives a position signal from the encoder 2 and controls the motor 1. and

The rotor of the motor 1 rotates around the main shaft when the drive current output from the motor control device 3 flows through the coils. In this specification, the rotation of the rotor in the motor 1 is also referred to as the rotation of the motor 1 . The rotational speed of the motor 1 (hereinafter also simply referred to as “speed”) is controlled by the motor control device 3 by adjusting the drive current flowing through the coils.

The encoder 2 outputs encoder pulses each time the motor 1 rotates by a predetermined angle. An encoder pulse is a position signal indicating that the motor 1 has rotated by a predetermined angle. An encoder pulse is generated each time the motor 1 rotates by a predetermined angle. The generated encoder pulse is output to the motor control device 3 . Either an incremental rotary encoder or an absolute rotary encoder may be used as the encoder 2 . The detection method of the encoder 2 may be optical or magnetic, and may be optical, transmissive, or reflective. In the following description of this specification, a transmissive incremental rotary encoder will be described as an example, but the present invention is not limited to this.

The motor control device 3 includes a control section 4 and a storage section 5 storing various programs and parameter groups. The motor control device 3 receives encoder pulses output from the encoder 2, determines the rotational speed of the motor 1, and controls the current flowing through the coils of the motor 1 in accordance with the determined rotational speed to rotate the motor 1. to control.

FIG. 2 is a schematic configuration diagram showing a configuration example of the control section 4 of the motor control device 3. As shown in FIG. The control unit 4 includes, for example, a processor such as a CPU (Central Processing Unit), various memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), a timer (counter), an A/D conversion circuit, an input/output I/ It has hardware elements such as an F circuit and a clock generation circuit, and is composed of a program processing unit (for example, a microcontroller: MCU) in which each component is connected to each other via a bus or a dedicated line. Alternatively, the control unit 4 may be configured by an FPGA (Field Programmable Gate Array) configured to implement functions equivalent to the hardware elements of the program processing device.

2 by controlling peripheral circuits such as an A/D conversion circuit and an input/output I/F circuit. The structure of the functional part is realized. That is, as shown in FIG. 2, the control unit 4 includes a speed determination processing unit 40, a PWM control unit 50, and a drive current control unit 60 as functional units.

The speed determination processing unit 40 determines the rotation speed of the motor 1 by receiving encoder pulses, and executes processing for generating speed information. The speed determination processing section 40 includes an encoder counter 41 (an example of a position signal counter), a periodic signal generation section 42 and a speed determination section 43 .

The encoder counter 41 counts the number of encoder interrupts. The encoder counter 41 measures the time from the time when the previous encoder interrupt was performed to the time when the current encoder interrupt was performed. The encoder counter 41 holds the counted number of encoder interrupts as an encoder count value. The encoder counter 41 that has counted encoder interrupts executes an encoder interrupt operation. In the encoder interrupt operation, the encoder counter 41 notifies the speed determination unit 43 of the encoder count value and the measured time. The encoder counter 41 counts the number of encoder interrupts at the timing of receiving encoder pulses. Therefore, the encoder count value obtained by counting the number of encoder interrupts is equal to the number of encoder pulses. Similarly, the time from the previous encoder interrupt to the current encoder interrupt is equal to the time from the time the previous encoder pulse was received to the time the current encoder pulse was received. be equal. The timing for counting encoder interrupts may be either the rising edge of the encoder pulse or the falling edge of the encoder pulse.

A periodic signal generator 42 generates a periodic signal at a predetermined period. The predetermined period is set to a constant time interval. The periodic signal is a signal that serves as a trigger for determining the rotational speed of the motor in the speed determining section 43 . The predetermined cycle is set according to the assumed rotation speed of the motor 1 . For example, in a stepping motor used as a normal actuator, any time interval such as 1/35,000 second interval can be set as the predetermined cycle, and is not limited to 1/35,000 second interval. As the stepping motor, any one of a VR type VR stepping motor, a PM type PM stepping motor, and an HB type HB stepping motor may be used.

The speed determination unit 43 determines the rotation speed of the motor based on the encoder count value, triggered by the generation of the periodic signal. Specifically, the speed determination unit 43 acquires the encoder count value from the encoder counter 41 . The speed determination unit 43 subtracts the previously acquired encoder count value from the last acquired encoder count value to calculate an increase in the encoder count value. The speed determination unit 43 determines the rotational speed of the motor using different methods depending on the increment of the encoder count value. For example, the speed determining unit 43 determines the rotation speed of the motor by different methods depending on whether the increment of the encoder count value is equal to or greater than a predetermined value or when the increment of the encoder count value is less than the predetermined value. The predetermined value is a threshold for determining the method by the speed determination unit 43 . The predetermined value may be, for example, a boundary value (for example, 2) between the number of encoder pulses for judging that the motor 1 is rotating at a low speed and the number of encoder pulses for judging that the motor 1 is rotating at a high speed. good.

When the encoder count value is equal to or greater than a predetermined value, the speed determination unit 43 determines the number of encoder pulses generated by the encoder 2 per one rotation of the motor 1, the period at which the periodic signal generation unit 42 generates the periodic signal, The speed is calculated based on the increment value of the encoder count value. Specifically, the speed determining unit 43 calculates the speed V1 based on (Equation 1). The speed determination unit 43 determines the calculated value V1 as the rotation speed V of the motor at the current generation timing of the periodic signal (hereinafter also simply referred to as “speed V”).

V1=2πp/αT (Formula 1)
In the above (Equation 1), α is the number of encoder pulses generated in the encoder 2 per one rotation of the motor 1 . T is the pulse interval of the encoder. p is the increment value of the encoder count value. π is the circular constant. Note that the speed determination unit 43 may be configured to calculate the speed by means other than (Formula 1). For example, the speed determining unit 43 may be configured to calculate the speed using a coefficient or a constant for the value obtained using (Formula 1).

When the increase value of the encoder count value is less than a predetermined value, the speed determination unit 43 determines the rotation speed V of the motor by different methods depending on whether the increase value is 0 or not. First, the case where the increment value is 0 will be described. The speed determination unit 43 has a periodic signal counter 44 . The periodic signal counter 44 is a counter that counts the number of times the incremented value of the encoder count value becomes 0 consecutively. In the present embodiment, a cycle in which the increment value of the encoder count value becomes 0 is called a low count cycle. That is, the periodic signal counter 44 is a counter that counts the number of consecutive low count periods. When the increment value of the encoder count value is 0, the speed determination unit 43 counts the number of consecutive low count cycles by incrementing the cycle signal counter 44 by one. The speed determination unit 43 calculates the speed upper limit value based on the count value of the periodic signal counter 44 . The speed determining unit 43 sets the count value of the periodic signal counter 44 to "0" when the increment value of the encoder count value is not zero.

The speed upper limit value is a value that decreases according to the number of consecutive low count cycles. The speed upper limit value is, for example, a value that decreases according to the count value of the periodic signal counter 44 . The speed upper limit value is a value Vm that is the upper limit of the speed that can be determined as the speed at the current periodic signal generation timing when the increment value of the encoder count value is 0 in the speed determination unit 43 . The speed determination unit 43 is based on the number of times the encoder pulse is generated in the encoder 2 per one rotation of the motor 1, the period in which the periodic signal generation unit 42 generates the periodic signal, and the count value of the periodic signal counter 44. to calculate the speed upper limit value Vm. Specifically, the speed determining unit 43 can use the speed upper limit value Vm calculated based on the following (Equation 2).

Vm=2π/αnT (Formula 2)
In the above (Equation 2), α is the number of encoder pulses generated in the encoder 2 per one rotation of the motor 1 . T is a predetermined period for generating the periodic signal in the periodic signal generator 42 . n is the count value of the periodic signal counter 44 . π is the circular constant.

When the increment of the encoder count value is less than the predetermined value and the increment is 0, the speed determination unit 43 compares the calculated upper limit speed Vm with the speed V2, and determines the smaller speed. is determined as the rotation speed V of the motor. Note that the speed V2 is determined by the speed determination unit 43 based on the notification by the encoder interrupt operation.

Here, the speed V2 determined by the speed determination unit 43 based on the notification by the encoder interrupt operation will be specifically described. The speed determination unit 43 performs processing for determining the rotation speed of the motor with the generation of the periodic signal as a trigger, as well as processing for determining the rotation speed of the motor with the encoder interrupt operation as a trigger. Triggered by the encoder interrupt operation, the speed determination unit 43 determines the number of encoder pulses generated by the encoder 2 per one rotation of the motor 1 and the time from when the previous encoder pulse was received to when the current encoder pulse is received. and the velocity V2 is calculated based on the time of . Specifically, the speed determination unit 43 calculates the speed V2 based on the following (Equation 3).

V2=2π/αt (Formula 3)
In (Equation 3) above, α is the number of encoder pulses generated in the encoder 2 per one rotation of the motor 1 . t is the time from the time when the previous encoder pulse was received to the time when the current encoder pulse was received. The unit of t is seconds. π is the circular constant. Note that the speed determination unit 43 may be configured to calculate the speed V2 by means other than (Equation 3). For example, the speed determination unit 43 may be configured to calculate the speed using a coefficient or a constant for the value obtained using (Formula 3).

Next, the rotational speed of the motor determined by the speed determination unit 43 triggered by the generation of the periodic signal when the increment value of the encoder count value is less than the predetermined value and not 0 will be described. If the increment value of the encoder count value is less than the predetermined value and the increment value is not 0, the speed determination unit 43 sets the speed V2 calculated based on the last encoder interrupt operation as the rotation speed V of the motor. decide.

The speed determination unit 43 generates speed information based on the determined rotational speed of the motor and transfers the speed information to the PWM control unit 50 . The speed determining unit 43 can generate, for example, a predicted value of the current rotational speed of the motor 1 as speed information. The PWM control unit 50 generates a PWM signal based on speed information and a target speed indicating a target value of rotation speed. The generated PWM signal is a signal that gives the motor 1 a torque that brings the speed information closer to the target speed.

A PWM control unit 50 generates a PWM signal based on the speed information. The PWM control unit 50 generates a PWM signal for controlling the motor 1 to rotate at a rotation speed corresponding to the speed determined by the speed determination unit 43 .

The drive current control section 60 adjusts the amount of current to be supplied to the coils of the motor 1 based on the PWM signal received from the PWM control section 50 . By adjusting the amount of current flowing through the coils of the motor 1, the speed of the motor 1 can be controlled.

Next, operation of the motor control system of the first embodiment will be described.

FIG. 3 is a flow chart showing an example of encoder interrupt operation in the operation of the motor control system. The encoder counter 41 counts the number of encoder interrupts and holds the counted number of encoder interrupts as an encoder count value (step S101). In step S101, the encoder counter 41 measures the time from the last encoder interrupt to the current encoder interrupt. The encoder counter 41 passes the measured time to the speed determining section 43 (step S102).

The speed determination unit 43 calculates the speed V2 based on (Equation 3) (step S103). The speed determination unit 43 can calculate the speed V2 based on the time passed from the encoder counter 41 .

FIG. 4 is a flow chart showing an example of periodic interrupt operation in the operation of the motor control system. The speed determining unit 43 subtracts the previously acquired encoder count value from the last acquired encoder count value to calculate an increase in the encoder count value (step S201).

The speed determination unit 43 determines whether or not the increase in the encoder count value of the encoder counter 41 is equal to or greater than a predetermined value (step S202). When the speed determination unit 43 determines that the increase in the encoder count value is equal to or greater than the predetermined value (step S202: YES), the speed determination unit 43 calculates the speed V1 according to (Equation 1) (step S203). The speed determination unit 43 determines the calculated speed V1 as the rotation speed V of the motor.

When the speed determination unit 43 determines that the increase in the encoder count value is not equal to or greater than the predetermined value (step S202: NO), it determines whether the increase in the encoder count value is 0 (step S204). When the increment value of the encoder count value is 0 (step S204: YES), the speed determination unit 43 calculates the speed upper limit value Vm according to (Equation 2) (step S205).

The speed determination unit 43 compares the calculated speed upper limit value Vm and the speed V2, and determines the smaller speed as the rotation speed V of the motor (step S206).

When the increment of the encoder count value is less than the predetermined value and the increment is not 0 (step S204: NO), the speed determination unit 43 determines the speed V2 as the rotation speed V of the motor (step S207).

After step S203, step S206, or step S207, the speed determining unit 43 generates speed information based on the calculated or determined rotational speed V of the motor (step S208). The speed determination unit 43 can pass the generated speed information to the PWM control unit 50 . The speed determination unit 43 can generate a command value according to the calculated or determined rotational speed V of the motor as speed information. For example, the command value can be set such that the determined motor rotation speed V becomes the target rotation speed of the motor 1 .

The PWM control unit 50 generates a PWM signal based on the speed information and transfers it to the drive current control unit 60 (step S209). Upon receiving the PWM signal, the drive current control unit 60 adjusts the amount of current based on the received PWM signal and outputs it to the motor 1 (step S210).

As shown in FIG. 4 , the speed determining unit 43 determines the rotational speed V of the motor that is adjusted so as not to exceed the speed upper limit value Vm that decreases according to the count value n of the periodic signal counter 44 . Even if the encoder pulse temporarily rises due to motor vibration or rotation unevenness, the speed determination unit 43 can update the speed more quickly. Therefore, the motor control device 3 can drive the motor 1 more stably.

Temporary upswing of encoder pulses due to motor vibration and rotational unevenness will now be described.

5 and 6 are diagrams showing examples of encoder pulses output from the encoder. The control unit 4 detects the rotational speed and rotational direction of the motor by counting the rising edges or falling edges of the encoder pulses output in two phases (A phase and B phase) from the encoder 2. there is When the motor rotates at a constant rotational speed, the encoder 2 outputs encoder pulses at constant intervals in the A phase and B phase. For example, the control unit 4 can detect the rotation speed of the motor based on how many rising edges are counted during a predetermined period in the A phase and the B phase. Further, the control unit 4 can detect the rotation direction based on the order of the phases in which the encoder pulses are counted. For example, when the controller 4 counts the rising edge in the A phase and then counts the rising edge in the B phase, it can detect that the motor is rotating forward. Conversely, when the controller 4 counts the rising edge in the A phase after counting the rising edge in the B phase, it can detect that the motor is rotating in the reverse direction.

FIG. 5(a) shows encoder pulse output in the case of forward rotation. An encoder pulse of A in FIG. 5(a) indicates an A-phase encoder pulse. An encoder pulse of B in FIG. 5A indicates a B-phase encoder pulse. FIG. 5(b) shows the encoder pulse output in the case of reverse rotation. An encoder pulse of A in FIG. 5B indicates an A-phase encoder pulse. The B encoder pulse in FIG. 5B indicates the B-phase encoder pulse. According to FIG. 5, when the motor 1 is rotating normally, A-phase encoder pulses and B-phase encoder pulses are alternately output.

FIG. 6A shows encoder pulse output when vibration occurs. An encoder pulse of A in FIG. 6A indicates an A-phase encoder pulse. An encoder pulse of B in FIG. 6A indicates a B-phase encoder pulse. When the motor 1 is rotating normally, the rising pulse of the B-phase encoder pulse b1 is output after the rising pulse of the A-phase encoder pulse a1. However, when the motor 1 vibrates, the encoder pulse output changes. For example, the encoder 2 outputs the rising and falling pulses of the B-phase encoder pulse b1 twice after outputting the falling pulse of the encoder pulse a1. Thus, when vibration occurs, the encoder 2 may continuously output encoder pulses b1 indicating the same rotational position. In this case, the encoder 2 outputs more encoder pulses than the number of encoder pulses resulting from the actual rotation, resulting in a temporary upward swing of the encoder pulses.

FIG. 6(b) shows the encoder pulse output when rotation unevenness occurs. An encoder pulse of A in FIG. 6B indicates an A-phase encoder pulse. When rotation unevenness occurs in the motor 1, the encoder 2 outputs encoder pulses whose intervals are locally wide or narrow. For example, according to FIG. 6B, the output intervals of encoder pulses a1, a2, a3, b1 and b2 are different. In this way, when rotation unevenness occurs, the encoder 2 outputs encoder pulses at different intervals, making it difficult for the motor control device 3 to stably control the speed.

Even if the motor is controlled to always rotate constantly, the influence of disturbances and the like may cause vibrations and uneven rotation, resulting in temporary overshoot in encoder pulses. In the motor control system of the present embodiment, the speed determination section 43 can update the speed more quickly even if there is a temporary upward deflection of the encoder pulse.

FIG. 7 is a diagram showing the relationship between encoder interrupts and period interrupts and speed. FIG. 7A shows that an encoder interrupt due to vibration and an encoder interrupt due to rotation unevenness occur at intervals of period T of the period interrupt timing. In FIG. 7A, solid lines indicate periodic interrupt timings S1, S2, S3, . . . S11, and broken lines indicate encoder interrupt timings. FIG. 7(b) shows temporal changes in the rotation speed of the motor determined by the speed determining unit 43 at the periodic interrupt timing shown in FIG. 7(a).

In the example shown in FIG. 7, an encoder interrupt due to vibration occurs between timings S2 and S3 of the periodic interrupt, and an encoder interrupt due to vibration occurs between timings S5 and S6 of the periodic interrupt. As shown in FIG. 3, the speed determination unit 43 calculates the speed V2 using (Equation 3) when there is a timing at which an encoder interrupt occurs.

As shown in FIG. 4, the speed determination unit 43 calculates the speed V1 when the increment of the encoder count value at the timing of the periodic interrupt is equal to or greater than a predetermined value. Therefore, when vibration or rotation unevenness occurs and the increment of the encoder count value becomes equal to or greater than a predetermined value at the timing of the periodic interrupt, the speed determination unit 43 calculates the speed V1 based on the temporary overrun encoder count value. do. The rotation speed V of the motor is determined to be V1 at the timing of the periodic interrupt.

In the example shown in FIG. 7, it is considered that the increment value of the encoder count value is "2" at the timing S3 of the periodic interrupt, and the increment value of the encoder count value is "3" at the timing S6 of the periodic interrupt. be done. Under the condition that the predetermined value of the encoder count value is "2", the speed determining unit 43 determines that the increment of the encoder count value is equal to or greater than the predetermined value at both the periodic interrupt timings S3 and S6. Therefore, the speed determination unit 43 determines V11 calculated based on (Equation 1) as the rotational speed V of the motor at the timing S3 of the periodic interrupt, and calculates based on (Equation 1) at the timing S6 of the periodic interrupt. The resulting V12 is determined as the rotation speed V of the motor.

In the motor control system of this embodiment, in the case of a temporary overrun due to vibration or rotation unevenness, the encoder count value becomes less than the predetermined value at the timing of the next periodic interrupt. Therefore, at the timing of the next periodic interrupt, the speed determination unit 43 determines the motor rotation speed V2 as the motor rotation speed V depending on whether the increment value of the encoder count value is 0 or not. The rotational speed V of the motor is adjusted by calculating the speed upper limit value Vm.

In the example shown in FIG. 7, it is considered that the increment value of the encoder count value is 0 at the timings S4 and S7 of the periodic interrupts subsequent to the timings S3 and S6 of the periodic interrupts. Therefore, the speed determination unit 43 calculates the upper limit speed _Vm1 at the timing S4 of the periodic interrupt, and compares V2 calculated at the timing of the encoder interrupt with the upper limit speed _Vm1 , and selects the smaller one as the motor speed. is determined as the rotation speed V of . Similarly, the speed determination unit 43 calculates the upper limit speed _Vm2 at the timing S7 of the periodic interrupt, and compares V2 calculated at the timing of the encoder interrupt with the upper limit speed _Vm2 , and selects the smaller one. Determine the rotation speed V of the motor. In FIG. 7, V _m1 and V _m2 calculated at the timings S3 and S7 of the periodic interrupt are shown to be smaller than V2 calculated at the timing of the encoder interrupt.

In the case of a temporary upswing, the low count cycle continues like the cycle interrupt timings S4 to S5 and S7 to S10 in FIG. Therefore, the speed determining unit 43 determines the rotational speed V of the motor by calculating that the speed upper limit value Vm is V _m1 and (1/2)V _m1 at the timings S4 to S5 of successive periodic interrupts. Similarly, the speed determination unit 43 sets the speed upper limit value Vm to _Vm2 , (1/2) _Vm2 , (1/3) _Vm2 , (1/n)V _m2 , and the rotational speed V of the motor is determined. The speed upper limit values V _m1 and V _m2 decrease according to the number of consecutive low count cycles. Therefore, every time the low count cycle continues, the motor rotation speed V determined by the speed determination unit 43 gradually decreases and is updated to a value close to the original speed.

As described above, in the motor control system of this embodiment, even if the encoder pulse temporarily rises, the temporarily increased speed is updated to a value close to the original speed at the timing of the periodic interrupt. Therefore, the rotation of the motor can be stabilized.

(Modification of embodiment)
In the above embodiment, a specific example has been described using the motor control system having the configuration shown in FIG. 1, but the configuration is not limited to that shown in FIG. Similarly, the configurations of the motor 1, the encoder 2, and the motor control device 3 are not particularly limited to the examples described above.

In the above embodiment, the processing flows shown in FIGS. 3 and 4 are specific examples, and the processing flows are not limited to these. For example, as shown in FIG. 4, the process of resetting the count value n of the periodic signal counter 44 to 0 (step S203) may be executed before the process of calculating the rotation speed V of the motor (step S202).

REFERENCE SIGNS LIST 1 Motor 2 Encoder 3 Motor control device 4 Control unit 5 Storage unit 40 Speed determination processing unit 41 Encoder counter 42 Periodic signal generation unit 43 Speed determination unit 44 ... periodic signal counter, 50 ... PWM control section, 60 ... drive current control section

Claims (6)

a position signal counter that counts the number of times a position signal that is generated each time the motor rotates by a predetermined angle is received;
a periodic signal generation unit that generates a periodic signal for each predetermined period;
If the number of counts of the position signal counter in the predetermined cycle is equal to or greater than a predetermined value, the rotation speed of the motor calculated based on the number of counts is determined as the rotation speed of the motor at the current generation timing of the periodic signal, and If the position signal counter does not count in a predetermined cycle, the time from the time when the position signal counter last received the position signal to the time when the position signal was received immediately before the last time is used. The smaller one of the determined motor rotation speed and the speed upper limit value that is the upper limit of the speed that can be determined as the speed at the current periodic signal generation timing is the motor rotation speed at the current periodic signal generation timing. a speed determining unit for determining;
a drive signal generator that generates a drive signal for driving the motor according to the determined rotation speed of the motor,
The speed determination unit controls the speed upper limit so that the rotational speed of the motor to be determined becomes smaller according to the number of consecutive low count cycles, which are cycles in which the position signal counter does not count in the predetermined cycle. A motor controller that determines the value. The motor control device according to claim 1,
The periodic signal generator generates periodic signals at the same time intervals regardless of the rotation speed of the motor.
motor controller. The motor control device according to claim 1 or 2,
When the number of counts of the position signal counter in the predetermined cycle is equal to or greater than a predetermined value, the speed determination unit determines the number of times the position signal is generated per rotation of the motor, the predetermined cycle, and the determining the rotational speed of the motor at the timing of generating the current periodic signal based on the number of counts of the position signal counter in a predetermined period;
motor controller. The motor control device according to any one of claims 1 to 3,
The speed determination unit includes the number of times the position signal is generated per rotation of the motor, the predetermined period, the count number of the position signal counter in the predetermined period, and the number of consecutive low count periods. and determining the upper speed limit based on
motor controller. a motor control device according to any one of claims 1 to 4;
a motor rotationally driven based on a drive signal output from the motor control device;
an encoder that detects the rotational position of the motor;
motor control system. a position signal counting step of counting the number of times a position signal is received each time the motor rotates a predetermined angle; a periodic signal generating step of generating a periodic signal every predetermined period; The rotation speed of the motor calculated based on the number of counts of the signal count step is determined as the rotation speed of the motor at the time when the periodic signal is generated this time. is the rotation speed of the motor determined based on the time from the time when the position signal counter received the last position signal to the time when the position signal was received immediately before the last time, and the timing of generating the current periodic signal. a speed determination step of determining, as the rotation speed of the motor at the current generation timing of the periodic signal, the smaller one of the speed upper limit, which is the upper limit of the speed that can be determined as the speed;
a drive signal generating step for generating a drive signal for driving the motor so as to achieve the determined rotational speed of the motor;
In the speed determination step, the rotational speed of the motor to be determined is reduced according to the number of consecutive low count cycles, which are cycles in which the position signal count step is not counted in the predetermined cycle. A motor control method, including determining an upper limit.

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