Motor drive control device, motor unit and motor drive control method

Abstract

The present invention relates to a motor drive control device, a motor unit, and a motor drive control method. The motor drive control device (1) includes: a feedback control unit (12) that calculates the motor operation amount (Sad) in such a way that the rotational speed (S3) of the motor (4) is consistent with the target rotational speed (S1); a drive control signal generation unit (14) that generates a drive control signal (Sd) based on the operation amount; a current variation detection unit (16) that detects the variation of the current flowing to the motor; a correction indication unit (19) that instructs the correction of the operation amount when the current variation detection unit detects the variation of the current flowing to the motor; and a correction unit (13) that corrects the operation amount and provides the corrected operation amount (S2) to the drive control signal generation unit when the correction of the operation amount is instructed by the correction indication unit.

Description

Technical Field

[0001] This invention relates to a motor drive control device, a motor unit, and a motor drive control method. Background Technology

[0002] As methods for controlling the speed (rotational speed) of a motor, known feedback control methods include PI (Proportional-Integral) control and PID (Proportional-Integral-Differential) control.

[0003] For example, a motor drive control device employing PID control performs proportional (P), integral (I), and derivative (D) operations based on the deviation between the target rotational speed (target value) and the actual rotational speed (control quantity) of the motor. In this way, the operating quantity of the motor is calculated in such a way that the deviation becomes 0 (zero), and the motor is driven based on the operating quantity (for example, see Patent Document 1). Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-153224 Summary of the Invention The problem that the invention aims to solve

[0005] However, when controlling the rotation of a motor using PI control or PID control, the following problems exist.

[0006] For example, when using PID control to keep the motor speed constant, if the input is inappropriate, the motor may exhibit an unstable state where its rotational speed fluctuates periodically with a differential frequency at intervals of several seconds. This instability is attributed to excessive input, i.e., an excessively short cycle (hereinafter referred to as the "feedback control cycle") for adjusting the power (current) supplied to the motor, or an excessively large power (current) supplied to the motor in each feedback control cycle.

[0007] Previously, determining whether a motor was in an unstable state was done by observing the actual operating sound and current waveform of the motor. Therefore, when applications requiring changes in motor size or specifications necessitated such changes, designers would simultaneously observe the motor's operating sound and current waveform while adjusting the power supplied to the motor and the feedback control cycle in each feedback control cycle to ensure stable motor operation. Consequently, adjusting the motor drive control algorithm during specification changes required considerable time.

[0008] The present invention is intended to eliminate the above-mentioned problems. Its purpose is to automatically adjust the motor operation amount in motor drive control without relying on human observation of the motor's operating state. Technical solution

[0009] A representative embodiment of the motor drive control device of the present invention is characterized by comprising: a control circuit for generating a drive control signal for controlling the drive of a motor; and a drive circuit for driving the motor according to the drive control signal. The control circuit includes: a feedback control unit for calculating an operating amount of the motor in a manner that makes the rotational speed of the motor consistent with a target rotational speed; a drive control signal generation unit for generating the drive control signal based on the operating amount; a current variation detection unit for detecting a variation in the current flowing to the motor; a correction indication unit for indicating a correction of the operating amount when a variation in the current flowing to the motor is detected by the current variation detection unit; and a correction unit for correcting the operating amount calculated by the feedback control unit according to the indication from the correction indication unit. The correction unit provides the operating amount calculated by the feedback control unit to the drive control signal generation unit without correction when no correction is indicated from the correction indication unit, and corrects the operating amount calculated by the feedback control unit and provides it to the drive control signal generation unit when correction is indicated from the correction indication unit. Invention Effects

[0010] According to one aspect of the present invention, the operating parameters of the motor in motor drive control can be adjusted automatically without relying on human observation of the motor's operating state. Attached Figure Description

[0011] Figure 1 This diagram illustrates the configuration of a motor unit equipped with a motor drive control device according to an embodiment of the present invention. Figure 2 This is a diagram illustrating an example of the configuration of a feedback control unit. Figure 3 This is a diagram illustrating an example of the periodic variation in motor current. Figure 4 This is a diagram illustrating an example of a correction method for the operational quantity implemented by the correction unit. Figure 5 This is a diagram illustrating the concept of operational quantity correction. Figure 6 This is a flowchart illustrating the process of correcting the operating quantity implemented by the motor drive control device of this embodiment. Detailed Implementation

[0012] 1. Overview of the implementation method First, a summary description of representative embodiments of the invention disclosed in this application will be given. It should be noted that, as an example, parentheses are used to refer to the reference numerals in the accompanying drawings corresponding to the constituent elements of the invention in the following description.

[0013] [1] A representative embodiment of the motor drive control device (1) of the present invention is characterized by comprising: a control circuit (2) for generating a drive control signal (Sd) for controlling the drive of a motor (4); and a drive circuit (3) for driving the motor according to the drive control signal. The control circuit includes: a feedback control unit (12) for calculating the operation amount (Sad) of the motor in such a way that the rotational speed of the motor is consistent with the target rotational speed (S1); a drive control signal generation unit (14) for generating the drive control signal based on the operation amount; a current variation detection unit (16) for detecting the variation of the current flowing to the motor; and a correction unit. The indicator unit (19) indicates the correction of the operating amount when the current change detection unit detects a change in the current flowing to the motor; and the correction unit (13) corrects the operating amount calculated by the feedback control unit according to the instruction from the correction indicator unit. If the correction unit does not indicate the correction of the operating amount from the correction indicator unit, it provides the operating amount calculated by the feedback control unit to the drive control signal generation unit without correction. If the correction unit indicates the correction of the operating amount from the correction indicator unit, it corrects the operating amount calculated by the feedback control unit and provides it to the drive control signal generation unit.

[0014] [2] In the motor drive control device described in [1] above, the correction indicator indicates the correction of the operating amount when the current variation detection unit detects a periodic change in the current flowing to the motor.

[0015] [3] In the motor drive control device described in [1] or [2] above, the correction indicator unit may further include a correction counter (20), which counts the number of times the current flow to the motor is detected by the current change detection unit, and the correction unit increases the amount of correction operation in stages according to the count value of the correction counter.

[0016] [4] In any of the motor drive control devices described in [1] to [3] above, the correction unit performs at least one of the following as a correction of the operating amount: reducing the operating amount provided to the drive control signal generation unit; and lengthening the cycle for updating the operating amount provided to the drive control signal generation unit.

[0017] [5] In the motor drive control device described in [4] above, the drive control signal is a PWM signal, the feedback control unit calculates a value of the duty cycle of the specified PWM signal as the operation quantity, and the correction unit corrects the operation quantity in a way that makes the value of the specified duty cycle calculated by the feedback control unit smaller.

[0018] [6] In the motor drive control device described in [4] above, the drive control signal is a PWM signal, the feedback control unit calculates the value of the duty cycle of the specified PWM signal as the operation quantity, and the correction unit corrects the operation quantity by updating and outputting the value of the specified duty cycle calculated by the feedback control unit in a longer period.

[0019] [7] The motor unit (100) of a representative embodiment of the present invention is characterized in that it includes the motor drive control device (1) and the motor (4) described in any one of [1] to [6] above.

[0020] [8] A representative embodiment of the present invention is a motor drive control method implemented by a motor drive control device (1), the motor drive control device (1) comprising: a control circuit (2) for generating a drive control signal (Sd) for controlling the drive of a motor (4); and a drive circuit (3) for driving the motor according to the drive control signal. The method is characterized by comprising: a first step (S12), in which the control circuit calculates an operation amount (Sad) of the motor in such a way that the rotational speed (S3) of the motor is consistent with a target rotational speed (S1); a second step (S12), in which the control circuit generates the drive control signal based on the operation amount; and a third step (S16-S18), in which the control circuit corrects the operation amount calculated in the first step when a change in the current flowing to the motor is detected.

[0021] 2. Specific examples of implementation methods Hereinafter, specific examples of embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that in the following description, common constituent elements in various embodiments will be given the same reference numerals and repeated descriptions will be omitted.

[0022] Implementation Method Figure 1 This diagram illustrates the configuration of a motor unit equipped with a motor drive control device according to an embodiment of the present invention.

[0023] Figure 1 The motor unit 100 shown includes a motor 4, a position detection device 5, and a motor drive control device 1.

[0024] Motor 4 is, for example, a brushless DC (direct current) motor with a single-phase coil (winding). The position detection device 5 is a device that generates a position detection signal Sp corresponding to the rotation of the rotor of the motor 4. The position detection device 5 is, for example, a Hall element. For instance, a Hall element corresponding to the coil of the motor 4 is disposed around the rotor of the motor 4 as the position detection device 5. The Hall element detects the magnetic poles of the rotor and generates and outputs a Hall signal with a voltage change based on the rotation of the rotor. The Hall signal output from the Hall element is input to the motor drive control device 1 as the position detection signal Sp. The position detection signal Sp is, for example, a pulse signal.

[0025] The motor drive control device 1 is a device for controlling the drive of the motor 4. The motor drive control device 1 obtains information such as the rotational position and rotational speed of the motor 4 based on the position detection signal Sp output from the position detection device 5, thereby detecting the rotational state of the motor 4 and controlling the drive of the motor 4.

[0026] It should be noted that encoders, rotary transformers, or other devices can be used instead of the Hall effect sensors to serve as the position detection device 5, and their detection signals can be input to the motor drive control device 1 as the position detection signal Sp. Furthermore, if the motor drive control device 1 performs motor 4 drive control based on a sensorless method, the position detection device 5 may not be required.

[0027] The motor drive control device 1 includes, for example, a control circuit 2 and a drive circuit 3. The motor drive control device 1 receives a DC voltage Vdc from an external DC power source. The DC voltage Vdc is supplied to the power line Lvdd via a protection circuit (not shown), and is then input to the control circuit 2 and the drive circuit 3 as the power supply voltage.

[0028] The power supply line Lvdd is a power supply path that supplies power to the control circuit 2 and then to the drive circuit 3 for driving the motor 4; for example, it is a wiring. In addition to the wiring, the power supply line Lvdd is also connected to a stabilizing capacitor for stabilizing the voltage of the power supply line Lvdd, the aforementioned protection circuit, etc.

[0029] It should be noted that, alternatively, the voltage of the power line Lvdd may not be directly supplied to the control circuit 2. Instead, for example, the voltage of the power line Lvdd may be stepped down by a regulator circuit and supplied to the control circuit 2 as the power supply voltage.

[0030] The drive circuit 3 is a circuit that drives the motor 4 based on the drive control signal Sd output from the control circuit 2, which will be described later. The drive control signal Sd is a signal used to control the drive of the motor 4, such as a PWM (Pulse Width Modulation) signal.

[0031] The drive circuit 3 switches the connection destination of the motor 4's coil between the power line Lvdd and the ground potential GND (Ground) based on the PWM signal, which serves as the drive control signal Sd. This switches the direction of the motor current, causing the motor 4 to rotate. For example, the drive circuit 3 consists of an inverter circuit (not shown) and a pre-drive circuit (not shown). The inverter circuit consists of multiple switching elements (e.g., transistors), and the pre-drive circuit generates multiple drive signals based on the drive control signal Sd to supply sufficient power to the switching elements of the inverter circuit.

[0032] Control circuit 2 is a circuit used to comprehensively control the operation of motor drive control device 1. In this embodiment, control circuit 2 is, for example, a program processing device configured as follows: a processor such as a CPU, various storage devices such as RAM (random access memory), ROM (read-only memory), flash memory, etc., and peripheral circuits such as counters (timers), A / D (analog-digital) conversion circuits, D / A (digital-to-analog) conversion circuits, clock generation circuits, and input / output interface circuits are interconnected via buses and dedicated lines. For example, control circuit 2 is a microcontroller (MCU).

[0033] It should be noted that the control circuit 2 and the drive circuit 3 can be packaged into a single semiconductor integrated circuit device (IC), or they can be packaged into separate integrated circuit devices, mounted on a circuit board, and electrically connected to each other on the circuit board.

[0034] Control circuit 2 has the following function: generating a drive control signal Sd and providing it to drive circuit 3, thereby controlling the energization of motor 4. Specifically, control circuit 2 performs feedback control as follows: based on a drive command signal Sc input from an external source (e.g., a host device) indicating a target value for the drive of motor 4 and a position detection signal Sp input from position detection device 5, it calculates an operation amount Sad to make motor 4 enter the drive state specified by the drive command signal Sc. Control circuit 2 generates a drive control signal Sd corresponding to the calculated operation amount Sad and provides it to drive circuit 3.

[0035] In addition, the control circuit 2 has the following function: when detecting changes in the motor current by monitoring the current flowing to the coil of the motor 4 (hereinafter also referred to as "motor current"), it corrects the operating quantity Sad calculated based on feedback control.

[0036] like Figure 1 As shown, the control circuit 2, as a functional unit for implementing the above-mentioned functions, includes, for example, a drive command signal parsing unit 11, a feedback control unit 12, a correction unit 13, a drive control signal generation unit 14, a rotation speed calculation unit 15, a current variation detection unit 16, and a correction indication unit 19.

[0037] The aforementioned functional units of control circuit 2 are implemented, for example, through program processing by the MCU that constitutes control circuit 2. Specifically, the processor constituting the MCU of control circuit 2 performs various calculations based on the program stored in the memory, controls various peripheral circuits constituting the MCU, thereby realizing the aforementioned functional units.

[0038] The drive command signal parsing unit 11 receives, for example, a drive command signal Sc output from a host device (not shown). As described above, the drive command signal Sc is a signal that indicates a target value for the drive of the motor 4, such as a speed command signal that indicates a target rotational speed of the motor 4.

[0039] The drive command signal parsing unit 11 parses the target rotational speed specified by the drive command signal Sc. For example, if the drive command signal Sc is a PWM signal with a duty cycle corresponding to the target rotational speed, the drive command signal parsing unit 11 parses the duty cycle of the drive command signal Sc and outputs the information of the rotational speed corresponding to that duty cycle as the target rotational speed S1.

[0040] The rotation speed calculation unit 15 is a functional unit that measures the rotation speed of the motor 4. For example, the rotation speed calculation unit 15 measures the rotation speed of the motor 4 based on the position detection signal (Hall signal) Sp of the Hall element, which is the position detection device 5, and outputs the measurement result as the rotation speed (actual rotation speed) S3.

[0041] The feedback control unit 12 is a functional unit that calculates the operation amount Sad of the motor 4 in a way that makes the rotational speed S3 of the motor 4 match the target rotational speed S1. Specifically, the feedback control unit 12 calculates the operation amount Sad of the motor 4 in a way that makes the deviation between the target rotational speed S1 output from the drive command signal parsing unit 11 and the rotational speed S3 output from the rotational speed calculation unit 15 zero. For example, the feedback control unit 12 calculates the operation amount Sad of the motor 4 according to each preset cycle (feedback control cycle). That is, the operation amount Sad is updated according to each preset feedback control cycle.

[0042] Figure 2 This is a diagram illustrating an example of the configuration of a feedback control unit. like Figure 2 As shown, the feedback control unit 12, as a specific example, has the function of performing PID control, and for example includes a subtractor 21, a PID controller 22, and an adder 26. The subtractor 21 calculates the difference between the target rotational speed S1 and the rotational speed S3, and outputs this difference (deviation) as the rotational speed error Sdif. The PID controller 22 performs PID calculations based on the rotational speed error Sdif output from the subtractor 21. Specifically, the PID controller 22 has a proportional (P) calculation unit 23, an integral (I) calculation unit 24, and a derivative (D) calculation unit 25.

[0043] The proportional operation unit 23 multiplies the rotational speed error Sdif output from the subtractor 21 by the proportional gain Gp to calculate the proportional operation value Sgp. The integral operation unit 24 multiplies the rotational speed error Sdif by the integral gain Gi and integrates the multiplied value over time to calculate the integral operation value Sgi. The differential operation unit 25 multiplies the rotational speed error Sdif by the differential gain Gd and differentiates the multiplied value over time to calculate the differential operation value Sgd.

[0044] Adder 26 adds the proportional operation value Sgp, the integral operation value Sgi, and the derivative operation value Sgd to obtain the value as the operation quantity Sad of motor 4.

[0045] Here, the operational quantity Sad contains information specifying the amount of drive required for the motor 4 to achieve a rotational speed S3 that matches the target rotational speed S1. For example, in the case where the motor 4 is driven by PWM as in this embodiment, the operational quantity Sad contains a value specifying the duty cycle (ratio of pulse on-time to PWM1 period) of the drive control signal Sd, which is a PWM signal. The operational quantity Sad is updated every preset feedback control cycle and output from the adder 26.

[0046] The current variation detection unit 16 is a functional unit that monitors the current flowing to the motor 4 (motor current) to determine whether there is a variation in the motor current. When a variation in the motor current is detected, the current variation detection unit 16 outputs a variation detection signal Sf. More preferably, the current variation detection unit 16 outputs a variation detection signal Sf when a periodic variation in the motor current is detected.

[0047] like Figure 1 As shown, the current variation detection unit 16 includes a current sampling unit 17 and a variation determination unit 18. The current sampling unit 17 samples the motor current per unit time and converts the sampled value into a digital signal, which is then output to the variation determination unit 18.

[0048] In this embodiment, a current detection circuit 6 is provided between the power supply line Lvdd and the ground potential to detect the motor current. The current detection circuit 6 is, for example, a voltage divider circuit consisting of resistors R1 and R2 connected in series between the power supply line Lvdd and the ground potential. For example, when driving the motor 4, power is supplied to the motor 4 via the power supply line Lvdd and the drive circuit 3. At this time, current flows in the power supply line Lvdd, and therefore, due to the parasitic resistance present in the power supply line Lvdd, the voltage of the power supply line Lvdd changes with the change in motor current. The current detection circuit 6 is a circuit that detects the change in this power supply voltage as a change in the power supply current (motor current).

[0049] The voltage detected by the current detection circuit 6 is input to the current sampling unit 17. The current sampling unit 17 samples the voltage input from the current detection circuit 6 as the measured value of the motor current.

[0050] It should be noted that, in this embodiment, an example is shown where a current detection circuit 6 is provided between the power supply line Lvdd and the ground potential to detect the motor current, but the method for monitoring the motor current is not limited to this. For example, as a method for monitoring the motor current, a resistor can be connected between the inverter circuit constituting the drive circuit 3 and the ground potential to detect the motor current, or a circuit can be provided to monitor the current (phase current) of each phase of the motor 4.

[0051] The change determination unit 18 is a functional unit that determines whether the motor current has changed based on the sampled value of the motor current measured by the current sampling unit 17. Here, the sampled value used to determine the change of motor current is, for example, the peak value of the motor current.

[0052] Specifically, the variation determination unit 18 determines whether there is a variation in the motor current by comparing the sampled values ​​of the motor current obtained by the current sampling unit 17. For example, the variation determination unit 18 detects the maximum and minimum values ​​of the current sampled values ​​within a certain period, and determines that there is a variation in the motor current if the difference between the maximum and minimum values ​​exceeds a predetermined threshold.

[0053] Figure 3 This is a diagram illustrating an example of the periodic variation in motor current. exist Figure 3 In the diagram, the horizontal axis represents time, and the vertical axis represents current. Referring to reference numeral 300, this indicates the change in current (motor current) flowing to motor 4 over time.

[0054] As described above, even if the externally input drive command signal Sc is a constant value, if the operating quantity (electricity) supplied to the motor in the motor's feedback control is inappropriate, the motor will still exhibit an unstable state where its rotational speed varies periodically with a differential frequency at intervals of several seconds. In this case, such as Figure 3 As shown, the motor current varies periodically.

[0055] In this embodiment, the current variation detection unit 16 detects variations in the motor current. More preferably, the current variation detection unit 16 detects variations such as... Figure 3 The periodic variation of the motor current is shown. For example, the variation determination unit 18 calculates the difference between the maximum and minimum values ​​of the sampled values ​​at regular intervals and determines whether a state in which the difference exceeds a predetermined threshold occurs periodically.

[0056] For example, such as Figure 3 As shown, the configuration is such that, in the range indicated by reference numeral 301 (also called range 301), the range indicated by reference numeral 302 (also called range 302), and the range indicated by reference numeral 303 (also called range 303), the variation determination unit 18 detects that the difference between the maximum and minimum values ​​of the sampled values ​​exceeds a predetermined threshold.

[0057] In this case, the variation determination unit 18 determines whether the time interval T1 between the detected range 301 of the first motor current variation and the detected range 302 of the second motor current variation, and the time interval T2 between the detected range 302 of the second motor current variation and the detected range 303 of the third motor current variation, are approximately the same (for example, within ±20% error range). If the intervals T1 and T2 are approximately the same, the variation determination unit 18 determines that a periodic variation in the motor current has occurred and outputs a variation detection signal Sf.

[0058] It should be noted that in the above example, when three changes in motor current are detected at predetermined intervals, the change determination unit 18 determines that a periodic change in motor current has occurred. However, it is not limited to this. When two changes in motor current are detected at predetermined intervals, the change determination unit 18 can quickly determine that a periodic change in motor current has occurred. When four or more changes in motor current are detected at predetermined intervals, the change determination unit 18 can determine that a periodic change in motor current has occurred.

[0059] The calibration indicator 19 is a functional unit that indicates the calibration of the operation quantity Sad. The correction instruction unit 19 instructs the correction unit 13 to correct the operating amount Sad calculated by the feedback control unit 12 based on the change detection signal Sf output from the change determination unit 18. If no change in motor current is detected by the current change detection unit 16, the correction instruction unit 19 does not instruct the correction of the operating amount Sad. On the other hand, if a change in motor current is detected by the current change detection unit 16, the correction instruction unit 19 instructs the correction of the operating amount Sad.

[0060] The calibration indication unit 19 includes, for example, a calibration counter 20 that counts the number of times the motor current changes detected by the current variation detection unit 16. The calibration indication unit 19 outputs the count value of the calibration counter 20 as a calibration indication signal S5.

[0061] Whenever a change detection signal Sf is output from the change determination unit 18, the correction instruction unit 19 increments the correction counter 20 (n→+1). On the other hand, for example, when the motor drive control device 1 is started, when the target rotation speed S1 specified by the drive command signal Sc changes, or when the input content of the drive command signal Sc changes, the correction instruction unit 19 resets the correction counter 20 (n→0).

[0062] The correction unit 13 is a function unit that corrects the operating quantity Sad calculated by the feedback control unit 12 according to the instruction from the correction instruction unit 19.

[0063] When the correction unit 13 is not instructed by the correction indication signal S5 to correct the operation quantity Sad, that is, when the count value of the correction counter 20 is 0 (zero), the correction unit 13 directly provides the operation quantity Sad calculated by the feedback control unit 12 as the operation quantity S2 to the drive control signal generation unit 14 without correction. For example, when the feedback control unit 12 updates the operation quantity Sad every cycle Tp1 (feedback control cycle), the correction unit 13 supplies the operation quantity Sad output from the feedback control unit 12 to the drive control signal generation unit 14 at the same cycle as the calculation cycle of the operation quantity Sad obtained by the feedback control unit 12. In other words, whenever the feedback control unit 12 calculates the operation quantity Sad, the correction unit 13 updates the operation quantity Sad and supplies it to the drive control signal generation unit 14.

[0064] On the other hand, when the correction instruction signal S5 indicates the correction of the operation quantity Sad, that is, when the count value of the correction counter 20 is 1 or more, the correction unit 13 corrects the operation quantity Sad calculated by the feedback control unit 12 and provides the corrected operation quantity S2 to the drive control signal generation unit 14. Hereinafter, the correction method implemented by the correction unit 13 will be described with reference to the accompanying drawings.

[0065] Figure 4 This is a diagram illustrating an example of a correction method for the operating quantity Sad implemented by the correction unit 13. Figure 5 This is a diagram illustrating the concept of correction for the operational quantity Sad.

[0066] As a specific method for correcting the operational quantity Sad implemented by the correction unit 13, an example can be shown. Figure 4 The two methods are shown.

[0067] like Figure 4 As shown, as a first correction example (correction example 1), the correction unit 13 corrects the operation quantity Sad by reducing (shrinking) the duty cycle of the PWM signal that serves as the drive control signal Sd. Specifically, the correction unit 13 outputs an operation quantity S2 that contains a value smaller than the value of the duty cycle of the PWM signal contained in the specified operation quantity Sad.

[0068] For example, such as Figure 5 As shown in the correction example 1, when the duty cycle of the PWM signal specified by the operation quantity Sad is D1%, the correction unit 13 outputs a corrected operation quantity S2 that includes a value of D2% that is smaller than the duty cycle D1% specified by the operation quantity Sad.

[0069] Therefore, compared with the case where the motor 4 is driven solely by the operating quantity Sad obtained from PID control calculation, the duty cycle of the drive control signal Sd is reduced, thus reducing the power (current) supplied to the motor 4 (coil).

[0070] Next, as Figure 4 As shown, as a second correction example (correction example 2), the correction unit 13 corrects the operation amount Sad by extending the period for updating the duty cycle value of the PWM signal provided to the drive control signal generation unit 14. That is, the correction unit 13 makes the period for updating the duty cycle of the drive control signal Sd longer than the period for calculating the operation amount Sad by the feedback control unit 12.

[0071] For example, such as Figure 5 As shown in the previous paragraph of the specific example of correction example 2, when the operation quantity Sad is not corrected, the correction unit 13 updates the operation quantity Sad provided to the drive control signal generation unit 14 with the same period as the period Tp1 (feedback control period) of the operation quantity Sad calculated by the feedback control unit 12, as described above.

[0072] On the other hand, such as Figure 5 As shown in the next paragraph of the specific example of correction example 2, when correcting the operation quantity Sad, the correction unit 13 updates the operation quantity S2 provided to the drive control signal generation unit 14 with a period Tp2 that is longer than the period Tp1 (feedback control period) of the operation quantity Sad calculated by the feedback control unit 12. As a result, the drive control signal generation unit 14 receives the operation quantity S2 (=Sad) by an amount greater than the timing delay (Tp2-Tp1) of the update of the operation quantity Sad by the feedback control unit 12.

[0073] As a result, the actual feedback control cycle becomes longer than the preset feedback control cycle, thus enabling the power supplied to motor 4 to change slowly.

[0074] It should be noted that the correction unit 13 may also correct the operation amount Sad by combining the first correction example and the second correction example described above. For example, if the duty cycle of the PWM signal (drive control signal Sd) specified by the operation amount Sad calculated by the feedback control unit 12 is D1%, and the period of the operation amount Sad provided to the drive control signal generation unit 14 is updated to Tp1, the correction unit 13 corrects the operation amount Sad by changing the duty cycle of the PWM signal to D2%, which is smaller than D1%, and provides the corrected operation amount S2 to the drive control signal generation unit 14 with a period Tp2, which is longer than the period Tp1. This allows for a further reduction in the amount of power supplied to motor 4.

[0075] In this way, the correction unit 13 performs at least one of the following as a correction of the operating amount: reducing the operating amount provided to the drive control signal generation unit 14 (first correction example) and lengthening the cycle of updating the operating amount provided to the drive control signal generation unit 14 (second correction example).

[0076] More preferably, the correction unit 13 may increase the amount of correction operation quantity Sad in stages according to the count value of the correction counter 20 (correction indication signal S5).

[0077] For example, the correction unit 13 may correct the operating quantity Sad by reducing the duty cycle of the drive control signal Sd by an amount of "n×Δd" based on the correction example 1 described above, when the count value of the correction counter 20 is "n" (n is an integer greater than or equal to 1). Here, Δd is the unit reduction rate of the duty cycle. For example, the correction unit 13 corrects the operation quantity Sad by decreasing the duty cycle of the drive control signal Sd by "1×Δd" when the count value of the correction counter 20 is "1", and by decreasing the duty cycle of the drive control signal Sd by "2×Δd" when the count value of the correction counter 20 is "2".

[0078] Alternatively, for example, the correction unit 13 may correct the operation amount Sad by increasing the period of the operation amount S2 (=Sad) updated to the drive control signal generation unit 14 by an amount of "n×ΔT" when the count value of the correction counter 20 is "n". Here, ΔT is the unit extension time of the update period. For example, the correction unit 13 corrects the operation amount Sad by increasing the period of the updated operation amount S2 (=Sad) provided to the drive control signal generation unit 14 by "1×ΔT" when the count value of the correction counter 20 is "1", and by increasing the period of the updated operation amount S2 (=Sad) provided to the drive control signal generation unit 14 by "2×ΔT" when the count value of the correction counter 20 is "2".

[0079] It should be noted that, alternatively, the correction unit 13 may correct the operating amount Sad by periodically changing the duty cycle of the drive control signal Sd and the operating amount S2 (=Sad) updated and provided to the drive control signal generation unit 14 according to the count value of the correction counter 20.

[0080] For example, the correction unit 13 corrects the operation amount Sad by increasing the period of the updated operation amount S2 (=Sad) supplied to the drive control signal generation unit 14 by ΔT when the count value of the correction counter 20 is "1", and by increasing the period of the updated operation amount S2 (=Sad) supplied to the drive control signal generation unit 14 by "ΔT" and decreasing the duty cycle of the drive control signal Sd by "Δd" when the count value of the correction counter 20 is "2".

[0081] Alternatively, the correction unit 13 may correct the operation amount Sad by increasing the period of the operation amount S2 (=Sad) updated to the drive control signal generation unit 14 by 2×ΔT and decreasing the duty cycle of the drive control signal Sd by "Δd" when the count value of the correction counter 20 is "3".

[0082] When the correction unit 13 resets the count value of the correction counter 20 (count value = 0), it stops the correction of the operation quantity and, as described above, provides the operation quantity Sad calculated by the feedback control unit 12 as the operation quantity S2 to the drive control signal generation unit 14 without correction.

[0083] In the following description, the correction unit 13 corrects the operation amount Sad in a manner that, as described above, changes at least one of the duty cycle of the drive control signal Sd and the cycle of the operation amount S2 (=Sad) updated and provided to the drive control signal generation unit 14 in stages, based on the count value of the correction counter 20 (correction indication signal S5).

[0084] The drive control signal generation unit 14 is a functional unit that generates a drive control signal Sd as a PWM signal based on the operation quantity S2 output from the correction unit 13. Specifically, the drive control signal generation unit 14 generates a PWM signal having a duty cycle specified by the operation quantity S2 provided from the correction unit 13 and outputs it as the drive control signal Sd. Whenever the value of the duty cycle specified by the operation quantity S2 is updated, the drive control signal generation unit 14 changes and outputs the duty cycle of the drive control signal Sd.

[0085] A drive control signal Sd is provided to the drive circuit 3, which drives the motor 4 based on the drive control signal Sd. This suppresses fluctuations in the motor current, and the motor 4 rotates at the target rotational speed S1.

[0086] Next, the process of correcting the operating quantity implemented by the motor drive control device 1 of this embodiment will be described.

[0087] Figure 6 This is a flowchart illustrating the process of correcting the operating quantity implemented by the motor drive control device 1 of this embodiment.

[0088] For example, when a DC voltage Vdc is applied to the motor drive control device 1 and the motor drive control device 1 starts, the motor drive control device 1 first determines whether a drive command signal Sc has been input (step S11). If no drive command signal Sc has been input (step S11: no), the motor drive control device 1 stands still until the drive command signal Sc is input.

[0089] When a drive command signal Sc is input (step S11: Yes), the motor drive control device 1 begins feedback control of the motor 4 (step S12). Specifically, the feedback control unit 12 calculates the operation quantity Sad through PID control calculation to make the rotational speed S3 of the motor 4 match the target rotational speed S1 specified by the drive command signal Sc. The drive control signal generation unit 14 generates a drive control signal Sd based on the operation quantity Sad (=S2). As a result, the motor 4 rotates.

[0090] Next, the motor drive control device 1 begins monitoring the motor current (step S13). Specifically, the current sampling unit 17 starts measuring (sampling) the voltage input from the current detection circuit 6 as the motor current, and the change determination unit 18 starts determining whether there is a change in the motor current based on the sampled value of the motor current measured by the current sampling unit 17.

[0091] Next, the motor drive control unit 1 determines whether the drive command signal Sc has been changed (step S14). Specifically, if the drive command signal Sc has been input when it was never input before, and the target rotation speed S1 re-specified by the drive command signal Sc is inconsistent with the previously specified target rotation speed S1, the motor drive control unit 1 determines that the drive command signal Sc has been changed (step S14: Yes). In this case, the correction instruction unit 19 resets the count value of the correction counter (n→0), stops the correction of the operational quantity, and returns to step S14 (step S15).

[0092] On the other hand, if the target rotation speed S1 specified by the drive command signal Sc is the same as the previously specified target rotation speed S1, the motor drive control device 1 determines that the drive command signal Sc has not been changed (step S14: no), and determines whether a change in motor current is detected (step S16).

[0093] Specifically, the variation determination unit 18 determines whether a periodic variation in the motor current is detected. If a periodic variation in the motor current is detected (step S16: Yes), the correction indication unit 19 increments the count value of the correction counter 20 (step S17).

[0094] Next, the motor drive control device 1 corrects the operating quantity Sad calculated by the feedback control unit 12 (step S18). Specifically, as described above, the correction unit 13 corrects the operating quantity Sad based on the count value of the correction counter 20 and outputs the corrected operating quantity S2 in such a way that at least one of the duty cycle of the PWM signal, which is the drive control signal Sd, and the period of updating the duty cycle is adjusted. After that, the motor drive control device 1 returns to step S14.

[0095] On the other hand, if no periodic variation in the motor current is detected (step S16: No), the motor drive control device 1 determines whether the count value of the correction counter 20 is 0 (step S19). If the count value of the correction counter 20 is not 0, that is, the count value is 1 or more (step S19: No), the motor drive control device 1 corrects the operating quantity Sad calculated by the feedback control unit 12 based on the count value of the correction counter 20 (step S18).

[0096] If the count value of the calibration counter 20 is 0 (step S19: Yes), the motor drive control device 1 does not perform calibration of the operation quantity Sad (step S20). After that, the motor drive control device 1 returns to step S14.

[0097] In this embodiment, the motor drive control device 1 corrects the operating quantity based on feedback control when it detects a change in the current (motor current) flowing to the motor 4. Therefore, the operating quantity Sad in feedback control can be automatically corrected without relying on observations of the motor's operating state performed manually.

[0098] Specifically, when the motor drive control device 1 detects a periodic change in the motor current, it corrects the operating quantity Sad calculated by the feedback control unit 12. Thus, when the motor experiences an unstable state in which its rotational speed changes periodically with a differential frequency at intervals of several seconds, the motor drive control device 1 can detect this unstable state and automatically correct the operating quantity Sad in the feedback control (e.g., PID control), thereby stabilizing the rotation of the motor 4.

[0099] In addition, the motor drive control device 1 also has a correction counter 20 that counts the number of times the motor current changes detected by the current change detection unit 16, and the motor drive control device 1 increases the amount of correction operation quantity Sad in stages according to the count value of the correction counter 20.

[0100] Therefore, the operation quantity Sad is corrected in stages until the variation in motor current is eliminated, thereby automatically setting the appropriate operation quantity required to achieve stable motor rotation.

[0101] In addition, the motor drive control device 1 performs at least one of the following as correction of the operating amount Sad: reducing the operating amount Sad provided to the drive control signal generation unit 14 and lengthening the cycle of updating the operating amount Sad provided to the drive control signal generation unit 14. Specifically, the motor drive control device 1 corrects the operating quantity Sad by reducing the value of the duty cycle of the drive control signal Sd (PWM signal) calculated by the feedback control unit 12. As a result, the power (current) supplied to the motor 4 (coil) can be reduced as described above, thus eliminating the motor instability caused by excessive operating quantity based on feedback control calculations.

[0102] Furthermore, the motor drive control device 1 corrects the operating quantity Sad by lengthening the period during which the duty cycle of the drive control signal Sd (PWM signal) provided to the drive control signal generation unit 14 is increased. As a result, the actual feedback control cycle is lengthened, thus allowing the power supplied to the motor 4 to change slowly, eliminating motor instability caused by excessive operating quantity based on feedback control calculations.

[0103] Extension of Implementation Methods The invention made by the inventors has been specifically described above based on the embodiments, but the invention is not limited thereto and various modifications can be made without departing from its spirit.

[0104] For example, in the above embodiment, the feedback control was described as PID control, but the feedback control is not limited to PID control and can also be PI control, etc.

[0105] Furthermore, in the above embodiment, an example is shown where the correction unit 13 corrects the operating amount when the variation determination unit 18 of the motor drive control device 1 detects a periodic change in the motor current. However, it is not limited to this and can also be configured such that the correction unit 13 quickly corrects the operating amount when the variation determination unit 18 detects a change in the motor current.

[0106] Furthermore, in the above embodiments, the following example was described: calculating the difference between the maximum and minimum values ​​of the sampled motor current, and determining a change in motor current if the difference exceeds a predetermined threshold, but this is not limited to this. Alternatively, for example, the change determination unit 18 may calculate the average value of the sampled motor current at regular intervals, and determine a change in motor current if the difference between the average values ​​of motor current in adjacent periods exceeds a predetermined threshold.

[0107] Furthermore, the flowchart above is just an example and is not limited to these limitations. For example, other processes can be inserted between steps, or the processes can be parallelized.

[0108] In the above embodiments, the type of motor 4 is not limited to a brushless DC motor. Furthermore, the motor 4 is not limited to a single phase, but can also be a multi-phase (e.g., three-phase) brushless DC motor. Explanation of reference numerals in the attached figures

[0109] 1: Motor drive control device 2: Control Circuit 3: Drive circuit 4: Motor 5: Position detection device 6: Current detection circuit 11: Drive command signal parsing unit 12: Feedback Control Department 13: Correction Department 14: Drive control signal generation unit 15: Rotational Speed ​​Calculation Unit 16: Current Variation Detection Unit 17: Current sampling section 18: Change Judgment Department 19: Calibration Indicator Section 20: Calibration Counter 100: Motor Unit S1: Target rotation speed S2: Operation quantity S3: Rotation speed S5: Calibration indicator signal Sad: Operational volume Sc: Drive command signal Sd: Drive control signal Sf: Change detection signal Sp: Position detection signal Lvdd: Power cord Vdc: DC voltage Gp: Proportional Gain Gi: Integral gain Gd: Differential gain Sdif: Rotational speed error Sgp: Scale operation value Sgi: Integral value Sgd: Differential value 21: Subtractor 22: PID controller 23: Proportional Calculation Section 24: Integral Operations Department 25: Differential Operations Unit 26: Adder

Claims

1. A motor drive control device, the motor drive control device comprising: A control circuit that generates a drive control signal for controlling the drive of the motor; and A drive circuit that drives the motor according to the drive control signal. The control circuit has: A feedback control unit calculates the operating quantity of the motor in a manner that makes the rotational speed of the motor match the target rotational speed; A drive control signal generation unit, which generates the drive control signal based on the operation quantity; A current variation detection unit detects variations in the current flowing to the motor; The calibration indicator, when the current variation detection unit detects a variation in the current flowing to the motor, indicates a correction of the operating amount; and A calibration unit that corrects the operating quantity calculated by the feedback control unit based on an instruction from the calibration instruction unit. The current variation detection unit detects the maximum and minimum values ​​of the sampled current flowing to the motor within a certain period. If the difference between the maximum and minimum values ​​exceeds a predetermined threshold, it is determined that there is a current variation flowing to the motor. If the correction unit does not indicate the correction of the operation amount from the correction instruction unit, it provides the operation amount calculated by the feedback control unit to the drive control signal generation unit without correction. If the correction unit indicates the correction of the operation amount from the correction instruction unit, it corrects the operation amount calculated by the feedback control unit and provides it to the drive control signal generation unit.

2. The motor drive control device according to claim 1, wherein, When the current variation detection unit detects a periodic variation in the current flowing to the motor, the correction indicator indicates a correction of the operating amount.

3. The motor drive control device according to claim 1, wherein, The calibration indicator also includes a calibration counter that counts the number of times the current variation detection unit detects changes in the current flowing to the motor. The correction unit increases the amount of correction operation in stages based on the count value of the correction counter.

4. The motor drive control device according to claim 1, wherein, The correction unit performs at least one of the following as a correction of the operating amount: reducing the operating amount provided to the drive control signal generation unit; and lengthening the cycle for updating the operating amount provided to the drive control signal generation unit.

5. The motor drive control device according to claim 4, wherein, The drive control signal is a PWM signal. The feedback control unit calculates the value of the duty cycle of the specified PWM signal as the operational quantity. The correction unit corrects the operating quantity in such a way that the value of the specified duty cycle calculated by the feedback control unit is reduced.

6. The motor drive control device according to claim 4, wherein, The drive control signal is a PWM signal, and the feedback control unit calculates the value of the duty cycle of the specified PWM signal as the operation quantity. The correction unit corrects the operational quantity by increasing the period during which it updates and outputs the value of the specified duty cycle calculated by the feedback control unit.

7. A motor unit, the motor unit comprising: The motor drive control device and the motor as described in any one of claims 1 to 6.

8. A motor drive control method implemented by a motor drive control device, the motor drive control device comprising: a control circuit, the control circuit generating a drive control signal for controlling the drive of the motor; and a drive circuit, wherein the drive circuit drives the motor according to the drive control signal, wherein, The motor drive control method includes: In the first step, the control circuit calculates the operating quantity of the motor in a manner that makes the rotational speed of the motor consistent with the target rotational speed; The second step is that the control circuit generates the drive control signal based on the operational quantity; and In the third step, if the control circuit detects a change in the current flowing to the motor, it corrects the operating amount calculated in the first step; if no change in the current flowing to the motor is detected, it does not correct the operating amount calculated in the first step. The third step includes the following steps: the control circuit detects the maximum and minimum values ​​of the sampled current flowing to the motor within a certain period of time, and determines that the current flowing to the motor changes when the difference between the maximum and minimum values ​​exceeds a specified threshold.

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