JP2023180771A - Motor control device and motor control method - Google Patents

Abstract

To provide a motor control device and a motor control method that can reduce the cost of control performed by detecting current flowing through a brush motor.SOLUTION: A motor control device includes: a current detection unit that detects a current value of current flowing through a brush motor; a current ripple extraction unit that extracts a current ripple included in the current based on the detected current value; a frequency analysis unit that obtains a frequency spectrum of the current ripple by frequency analysis of the extracted current ripple; an average current value calculation unit that calculates an average current value of the current based on the obtained frequency spectrum; and a drive control unit that controls driving of the brush motor based on the calculated average current value.SELECTED DRAWING: Figure 1

Description

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

A brush motor generally has a brush and a commutator, and is energized by contact between the brush and the commutator. The commutator is made up of a plurality of segments, and gaps are provided between the segments, so the brush and the commutator come into contact with each other at these gaps. If the brush and commutator come into contact with each other while energized, sparks will occur. This spark causes the brush to wear out.

Therefore, various techniques have been proposed for reducing brush wear by suppressing the generation of sparks. For example, Patent Document 1 listed below discloses a technique of cutting off current through PWM (Pulse Width Modulation) control at the timing when a brush and a commutator come into contact with each other and separate from each other. In this technique, the timing at which the brush and the commutator come into contact with each other is calculated based on the rotational speed of the rotor detected by an optical sensor, and the generation of sparks is suppressed by cutting off the current supply at the timing.

JP2020-61924A

When performing various controls such as control to suppress generation of sparks in a brush motor, the current value of the current flowing through the brush motor may be detected. Furthermore, an average current value obtained by averaging the detected current values may be used for control. In order to improve control accuracy, it is necessary to improve the detection accuracy of current values and average current values. However, in order to improve the detection accuracy of current values and average current values, additional components such as filters to smooth current values and memory to store sampling data and averaging programs are required. Yes, the cost will increase.

The present invention has been made in view of the above circumstances, and its purpose is to provide a motor control device and a motor control method that can reduce the cost of control performed by detecting the current flowing through the brush motor. It's about doing.

A motor control device according to one aspect of the present invention includes a current detection unit that detects a current value of a current flowing through a brush motor, and a current ripple extraction unit that extracts a current ripple included in the current based on the detected current value. a frequency analysis unit that obtains a frequency spectrum of the current ripple by frequency analysis of the extracted current ripple; and an average current value calculation unit that calculates an average current value of the current based on the obtained frequency spectrum. and a drive control unit that controls driving of the brush motor based on the calculated average current value.

The motor control method according to one aspect of the present invention includes a current detection step in which a current detection section detects a current value of a current flowing through a brush motor, and a current ripple extraction section in which a current ripple extraction section detects the current value based on the detected current value. a current ripple extraction step for extracting current ripples included in the current ripple; a frequency analysis step for a frequency analysis section to obtain a frequency spectrum of the current ripple by frequency analysis of the extracted current ripple; and an average current value calculation section. , an average current value calculation step of calculating an average current value of the current based on the acquired frequency spectrum; and a drive in which a drive control unit controls driving of the brush motor based on the calculated average current value. A control process.

As described above, according to the present invention, it is possible to reduce the cost of control performed by detecting the current flowing through the brush motor.

FIG. 1 is a block diagram showing an example of a schematic configuration of a motor control device according to the present embodiment. It is a figure which shows an example of the waveform which shows the time change of the electric current detected when the brush motor based on this embodiment is PWM-controlled. FIG. 3 is a diagram showing an example of a frequency spectrum obtained when the brush motor according to the present embodiment is subjected to PWM control. FIG. 3 is a diagram showing an example of a data structure of map information regarding driving states according to the present embodiment. FIG. 3 is a diagram showing an example of a data structure of map information regarding a rotational state according to the present embodiment. It is a figure showing the relationship between the drive record of the brush motor concerning this embodiment, and map information. 3 is a flowchart illustrating an example of the flow of processing according to the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings.

<1. Schematic configuration of motor control device>
A schematic configuration of a motor control device according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing an example of a schematic configuration of a motor control device according to this embodiment.
As shown in FIG. 1, the motor control device 1 includes a brush motor 11, a diode 12, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) 13, a diode 14, a power supply 15, and a current detection section 20. , a control section 30, and a storage section 40.

The brush motor 11 is a motor equipped with brushes and a commutator. In the brush motor 11, the contact between the brush and the commutator energizes the coil wound around the rotor, causing the rotor to rotate. The commutator of the brush motor 11 is composed of a plurality of segments. The commutator is provided so that a gap is created between each segment. Therefore, when the brush motor 11 is rotated by the power supplied from the power source 15, there is a timing when the brush and the commutator come into contact with each other in the gap portion. As a result, a current ripple occurs in the current flowing through the brush motor 11 as the brush motor 11 rotates.

Note that if the brush and commutator come into contact with each other while energized, sparks will be generated. These sparks cause brush wear, so in order to suppress brush wear, it is necessary to suppress the generation of sparks. In order to suppress the generation of sparks, it is sufficient that the brush and the commutator are not energized at the timing when they come into contact with each other. That is, it is sufficient if the voltage can be controlled to be turned off at the timing when the brush and the commutator come into contact with each other and turned on at the timing when the brush and the commutator come into contact again. This control can be realized by PWM (Pulse Width Modulation) control. Therefore, in this embodiment, the drive of the brush motor 11 is controlled by PWM control.

Diode 12 is a free wheel diode. MOSFET 13 constitutes a drive circuit for brush motor 11. Diode 14 is a backflow prevention diode.
The power source 15 is a power source for driving the brush motor 11. When rotating the brush motor 11, a drive signal is supplied to the gate of the MOSFET 13. As a result, MOSFET 13 is turned on, and power is supplied from power supply 15 to brush motor 11 .

The current detection unit 20 has a function of detecting the current value of the current flowing through the brush motor 11. The current detection section 20 outputs the detected current value to the control section 30.
Here, with reference to FIG. 2, the current value detected by the current detection section 20 will be explained. FIG. 2 is a diagram showing an example of a waveform showing a temporal change in current detected when the brush motor 11 according to the present embodiment is subjected to PWM control. The vertical axis of the waveform shown in FIG. 2 indicates the current value, and the horizontal axis indicates time. When the current detection unit 20 detects the current value flowing through the PWM-controlled brush motor 11 and shows the time change of the current value in a waveform, the waveform is as shown in FIG. 2, for example.

The control unit 30 has a function of controlling the overall operation of the motor control device 1. The control unit 30 is realized, for example, by causing a CPU (Central Processing Unit) included in the motor control device 1 as hardware to execute a program.
The control unit 30 generates a drive signal for driving the brush motor 11 and outputs it to the MOSFET 13. Specifically, the control unit 30 generates a signal (hereinafter also referred to as a "PWM signal") for driving the brush motor 11 by PWM control in accordance with the timing when the brush of the brush motor 11 and the commutator contact or separate. It is generated as a drive signal and output to the gate of MOSFET 13. That is, the PWM signal is a signal for controlling the MOSFET 13 to be turned on or off in accordance with the timing when the brush of the brush motor 11 and the commutator come into contact with each other or separate from each other.

The control unit 30 controls the drive of the brush motor 11 based on the current value detected by the current detection unit 20. Specifically, the control unit 30 estimates the driving state or rotational state of the brush motor 11 based on the current value, and performs control according to the estimated state.
For example, the control unit 30 estimates whether the driving state of the brush motor 11 is a normal state or an abnormal state. According to the estimation result of the drive state, the control unit 30 controls the drive of the brush motor 11 (hereinafter also referred to as "drive control"). In the drive control, for example, control to maintain or cut off power supply to the brush motor 11 is performed.
Further, the control unit 30 estimates whether the rotation state of the brush motor 11 is a low speed state, a normal state, or a high speed state. According to the estimation result of the rotation state, the control unit 30 controls the rotation speed of the brush motor 11 (hereinafter also referred to as "rotation speed control"). In the rotation speed control, for example, control is performed to maintain, increase, or decrease the rotation speed of the brush motor 11.
Note that the details of the functions of the control unit 30 will be described later.

The storage unit 40 has a function of storing various information. The storage unit 40 stores map information 41 as shown in FIG. 1, for example. The map information 41 is information used by the control unit 30 to estimate the driving state and rotational state of the brush motor 11.
Note that details of the map information 41 will be described later.

<2. Functional configuration of control section>
The schematic configuration of the motor control device 1 according to the present embodiment has been described above. Next, the functional configuration of the control unit 30 according to the present embodiment will be described with reference to FIGS. 1 to 6. As shown in FIG. 1, the control section 30 includes a current ripple extraction section 31, a frequency analysis section 32, an average current value calculation section 33, a maximum order detection section 34, a state estimation section 35, and a drive control section 36. Equipped with.

(1) Current ripple extraction section 31
The current ripple extraction unit 31 has a function of extracting current ripple from the current flowing through the brush motor 11. For example, the current ripple extraction section 31 extracts a current ripple included in the current based on the current value detected by the current detection section 20. As an example, the current ripple extraction unit 31 extracts the current ripple from the current value by passing the detected current value through a band pass filter as shown in FIG.

(2) Frequency analysis section 32
The frequency analysis unit 32 has a function of acquiring a frequency spectrum by frequency analysis. For example, the frequency analysis unit 32 acquires the frequency spectrum of the current ripple by frequency analysis of the current ripple extracted by the current ripple extraction unit 31. The frequency analysis unit 32 performs frequency analysis using, for example, Fourier transform (FT). The Fourier transform may be Fast Fourier Transform (FFT) or Discrete Fourier Transform (DFT).

Here, with reference to FIG. 3, the frequency spectrum acquired by the frequency analysis section 32 will be explained. FIG. 3 is a diagram showing an example of a frequency spectrum obtained when the brush motor 11 according to the present embodiment is subjected to PWM control. The vertical axis of the frequency spectrum shown in FIG. 3 indicates intensity, and the horizontal axis indicates order. Note that, in consideration of the ease of viewing the graph, FIG. 3 shows the frequency spectrum excluding the zero-order component from among the acquired frequency spectra.
In the frequency spectrum shown in FIG. 3, among the frequency spectra excluding the zero-order component, the component with the highest intensity is the tenth-order component. This tenth-order component is considered to be a spectrum of frequency components accompanying the rotation of the brush motor 11. In this way, the order at which the signal strength of the frequency spectrum is maximum is hereinafter also referred to as the "maximum order."
Further, in the frequency spectrum shown in FIG. 3, the intensity gradually weakens from the 11th order onward, but the intensity increases again at the 19th order. This 19th order component is considered to include noise generated by PWM control of the brush motor 11.

(3) Average current value calculation unit 33
The average current value calculation unit 33 has a function of calculating an average current value. Specifically, the average current value calculation unit 33 calculates the average current value of the current based on the frequency spectrum acquired by the frequency analysis unit 32. For example, the average current value calculation unit 33 calculates the average current value from the zero-order component of the frequency spectrum. Generally, the amplitude of the zero-order component of the frequency spectrum is said to be twice the amplitude of the average current value. Therefore, the average current value calculation unit 33 calculates a value obtained by halving the zero-order component of the frequency spectrum as the average current value.
In this way, the average current value calculation unit 33 can calculate the average current value from the zero-order component of the frequency spectrum by simple calculation processing. As a result, the motor control device 1 can omit a program for calculating the average current value through complicated calculation processing, so that the processing speed can be improved and the load on the memory can be reduced.

(4) Maximum order detection unit 34
The maximum order detection unit 34 has a function of detecting the maximum order from the frequency spectrum. For example, the maximum order detection section 34 detects the order at which the signal strength of the frequency spectrum is maximum as the maximum order from the frequency spectrum obtained by the frequency analysis section 32 excluding the zero-order component.

(5) State estimation unit 35
The state estimation unit 35 has a function of estimating the driving state and rotation state of the brush motor 11. For example, the state estimation unit 35 estimates the driving state of the brush motor 11 based on the average current value calculated by the average current value calculation unit 33. Specifically, in estimating the driving state, the state estimation unit 35 estimates whether the average current value is within the range of the target current value.
In this embodiment, the state estimating unit 35 estimates the driving state of the brush motor 11 using map information 41 indicating the correspondence between the average current value and the driving state. The map information 41 is information prepared in advance based on the driving performance of the brush motor 11.

Here, with reference to FIG. 4, the map information 41 used by the state estimation unit 35 to estimate the driving state of the brush motor 11 will be explained. FIG. 4 is a diagram showing an example of the data structure of map information 41 regarding the driving state according to the present embodiment.

As shown in FIG. 4, the data items of the map information 41 used for estimating the driving state include items for average current value and driving state. For the average current value, a range of normal average current values and a range of abnormal average current values are set based on the driving performance of the brush motor 11. The drive state is set to, for example, either "normal" indicating that the drive state is normal or "abnormal" indicating that the drive state is abnormal. That is, in the drive control of the brush motor 11, the average current value for which the drive state is "normal" in the map information 41 is set as the target current value.

As an example, the first record shows data in which the average current value is "~4.5 A" and the driving state is "abnormal." This indicates that the driving state of the brush motor 11 is "abnormal" when the calculated average current value is within the range of "~4.5 A". In this case, the drive control unit 36, which will be described later, controls the brush motor 11 to cut off the power supply.
Furthermore, the second record shows data in which the average current value is "4.5A to 5.5A" and the drive state is "normal". This indicates that the driving state of the brush motor 11 is "normal" when the calculated average current value is within the range of "4.5A to 5.5A". In this case, the drive control unit 36, which will be described later, performs control to maintain power supply to the brush motor 11.
Further, the third record shows data in which the average current value is "5.5 A~" and the driving state is "abnormal." This indicates that the driving state of the brush motor 11 is "abnormal" when the calculated average current value is within the range of "5.5 A". In this case, the drive control unit 36, which will be described later, controls the brush motor 11 to cut off the power supply.

The state estimating unit 35 estimates that the driving state of the brush motor 11 is normal or abnormal based on map information 41 as shown in FIG. If the range that includes the calculated average current value is associated with a "normal" driving state, the state estimation unit 35 estimates that the average current value is within the range of the target current value. . On the other hand, if the drive state of "abnormal" is associated with the range that includes the calculated average current value, the state estimation unit 35 estimates that the average current value is not within the range of the target current value. do.

Further, the state estimating unit 35 estimates the rotational state of the brush motor 11 based on the maximum order detected by the maximum order detecting unit 34. Specifically, the state estimation unit 35 estimates whether the rotation state of the brush motor 11 at the maximum order is within the range of the target rotation speed.
In the present embodiment, the state estimation unit 35 estimates the rotational state of the brush motor 11 using map information 41 indicating the correspondence between the order in the frequency spectrum of the current ripple and the rotational state of the brush motor 11. The map information 41 is information prepared in advance based on the driving performance of the brush motor 11.

Here, with reference to FIG. 5, the map information 41 used by the state estimation unit 35 to estimate the rotation state will be described. FIG. 5 is a diagram showing an example of the data structure of the map information 41 regarding the rotation state according to the present embodiment.

As shown in FIG. 5, the data items of the map information 41 used for estimating the rotational state include items for order and rotational state. The maximum order and the orders before and after the maximum order are set as the order based on the driving performance of the brush motor 11. The rotation state includes, for example, "low speed" indicating that the rotation state is a low speed state, "normal" indicating that the rotation state is a normal state, or "" indicating that the rotation state is a high speed state. One of the states "high speed" is set. Note that the order and the rotation state are associated so that the maximum order is "normal". That is, in controlling the rotational speed of the brush motor 11, the order whose rotational state is "normal" in the map information 41 is set as the target order, and the rotational speed corresponding to the order is set as the target rotational speed.

As an example, the first record shows data in which the order is "9th order" and the rotation state is "low speed." This indicates that when the detected maximum order is "9th order", the rotational state of the brush motor 11 is "low speed". In this case, the drive control unit 36, which will be described later, increases the rotation speed of the brush motor 11 and controls the rotation state to be "normal".
Further, the second record shows data in which the order is "10th order" and the rotation state is "normal". This indicates that the rotational state of the brush motor 11 is "normal" when the detected maximum order is "10th order". In this case, the drive control unit 36 maintains the rotation speed of the brush motor 11 and controls the rotation state to maintain the "normal" rotation state.
Further, the third record shows data in which the order is "11th order" and the rotation state is "high speed." This indicates that when the detected maximum order is "11th order", the rotational state of the brush motor 11 is "high speed". In this case, the drive control unit 36 lowers the rotation speed of the brush motor 11 to control the rotation state to be "normal".

The state estimating unit 35 estimates, based on the map information 41 as shown in FIG. 5, that the rotational state associated with the same order as the detected maximum order is the rotational state at the maximum order. If the “normal” rotational state is associated with the same order as the detected maximum order, the state estimation unit 35 determines that the rotational state of the brush motor 11 at the maximum order is within the range of the target rotational speed. It is estimated that On the other hand, if the rotation state of "low speed" or "high speed" is associated with the same order as the detected maximum order, the state estimation unit 35 determines that the rotation state of the brush motor 11 at the maximum order is the target rotation state. It is estimated that the state is not within the numerical range.

Here, with reference to FIG. 6, the relationship between the driving performance of the brush motor 11 and the map information 41 will be explained. FIG. 6 is a diagram showing the relationship between the driving record of the brush motor 11 and the map information 41 according to the present embodiment.

Based on the driving experience of the brush motor 11, when the rotation speed of the brush motor 11 is changed, the torque and current value of the brush motor 11 change, and the maximum order in the frequency spectrum of the ripple current flowing through the brush motor 11 also changes. I know it.
For example, FIG. 6 shows an example in which changes in each characteristic were actually measured when the number of rotations of the brush motor 11 was changed. In FIG. 6, characteristic A1 indicates the torque characteristic, and characteristic A2 indicates the current characteristic. As shown in FIG. 6, the torque characteristic A1 of the brush motor 11 indicates that the torque decreases as the rotation speed increases. Similarly, the characteristic A2 of the current flowing through the brush motor 11 indicates that the current value decreases as the rotation speed increases. Map information 41 is created from such actual measurement results.

As shown in FIG. 6, in the map information 41 used for estimating the driving state, a "normal" state is set for an average current value in the range of "4.5 to 5.5 A". Further, the "abnormal" state is set for a range in which the average current value is "~4.5A" or "5.5A~". That is, in the example shown in FIG. 6, the target current value range is "4.5 to 5.5 A".
Further, in the map information 41 used for estimating the rotational state, the "9th order" and "low speed" state is set for a rotation speed range of 2700±150 r/min. Further, the "normal" state of "10th order" is set for a rotation speed range of 3000±150 r/min. Further, the "11th order""highspeed" state is set for a rotation speed range of 3300±150 r/min. That is, in the example shown in FIG. 6, "10th order" is the target order, and "3000±150 r/min" is the range of the target rotation speed.

Based on the relationship shown in FIG. 6, the state estimation unit 35 can also diagnose the driving state of the brush motor 11 in more detail. For example, if the current value of the current flowing through the brush motor 11 is low and the rotation speed of the brush motor 11 is also low, the state estimation unit 35 can determine that the brush motor 11 is malfunctioning or the current detection unit 20 is malfunctioning. . Further, when the current value of the current flowing through the brush motor 11 is high and the rotation speed of the brush motor 11 is low, the state estimation unit 35 can determine that the brush motor 11 is in a restrained state. Further, when the current value flowing through the brush motor 11 is low and the rotation speed of the brush motor 11 is normal, the state estimation unit 35 can determine that there is an increase in the internal resistance of the brush motor 11, generation of sparks, etc.
Thereby, an abnormal state when the brush motor 11 is driven can be detected early.

Note that the map information 41 may be a table as shown in FIGS. 4 and 5, or may be mapped information as shown in FIG. 6.

(6) Drive control section 36
The drive control section 36 has a function of controlling the drive of the brush motor 11. For example, the drive control section 36 performs drive control of the brush motor 11 based on the average current value calculated by the average current value calculation section 33. Specifically, the drive control unit 36 controls the power supply to the brush motor based on the drive state estimated by the state estimation unit 35 based on the average current value calculated by the average current value calculation unit 33.
When the state estimation unit 35 estimates that the drive state of the brush motor 11 is “normal,” the drive control unit 36 performs control to maintain power supply to the brush motor 11.
On the other hand, when the state estimation unit 35 estimates that the drive state of the brush motor 11 is “abnormal”, the drive control unit 36 performs control to cut off power supply to the brush motor 11.

Further, the drive control section 36 controls the rotation speed of the brush motor 11 based on the rotation state estimated by the state estimation section 35 so that the rotation speed of the brush motor 11 becomes the target rotation speed. In this control, the drive control unit 36 generates a PWM signal with a duty ratio that makes the rotation speed of the brush motor 11 a target rotation speed, and outputs it to the MOSFET 13. MOSFET 13 is controlled to be turned on or off by this PWM signal. Thereby, the brush motor 11 is rotated at a desired number of rotations.

Specifically, the drive control unit 36 controls the rotation speed of the brush motor 11 so that the rotation state of the brush motor 11 at the maximum order is within the range of the target rotation speed, according to the estimation result by the state estimation unit 35. Control.
When the state estimation unit 35 estimates that the rotational state of the brush motor 11 is “normal”, the drive control unit 36 sends a PWM signal to maintain the rotational speed and maintain the rotational state as “normal”. control the duty ratio of Further, when the state estimating unit 35 estimates that the rotational state of the brush motor 11 is “low speed”, the drive control unit 36 increases the duty of the PWM signal so that the rotational speed becomes “normal” by increasing the rotational speed. Control the ratio. Further, when the state estimation unit 35 estimates that the rotational state of the brush motor 11 is “high speed”, the drive control unit 36 sets the duty of the PWM signal so that the rotational speed becomes “normal” by lowering the rotational speed. Control the ratio.

In the present embodiment, when the state estimation section 35 estimates that the drive state of the brush motor 11 is "normal", the drive control section 36 controls the rotation state estimated from the maximum order by the state estimation section 35. Based on this, the rotation speed of the brush motor 11 is controlled. In this way, the motor control device 1 can control the brush motor 11 more delicately by combining the drive control based on the average current value and the rotation speed control based on the maximum order.

<3. Processing flow>
The functional configuration of the control unit 30 according to the present embodiment has been described above. Next, the flow of processing according to this embodiment will be described with reference to FIG. 7. FIG. 7 is a flowchart showing an example of the flow of processing according to this embodiment.

As shown in FIG. 7, first, the state estimation unit 35 refers to the map information 41 stored in the storage unit 40 and sets a target current value in drive control of the brush motor 11 and a target order in rotation speed control. (Step S101).
Next, the current detection unit 20 detects the current value of the current flowing through the brush motor 11 (step S102).
Next, the current ripple extraction unit 31 extracts the current ripple included in the current flowing through the brush motor 11 based on the current value detected by the current detection unit 20 (step S103).
Next, the frequency analysis unit 32 obtains a frequency spectrum of the current ripple by performing Fourier transform on the current ripple extracted by the current ripple extraction unit 31 (step S104).
Next, the average current value calculation unit 33 calculates the average current value of the current based on the frequency spectrum acquired by the frequency analysis unit 32 (step S105).

Next, the state estimation unit 35 determines whether the average current value calculated by the average current value calculation unit 33 is normal (step S106). Specifically, the state estimating unit 35 refers to the map information 41 used for estimating the driving state and checks whether the calculated average current value is within the range of the target current value. If the average current value is within the range of the target current value, the state estimation unit 35 determines that the average current value is normal. On the other hand, if the average current value is outside the range of the target current value, the state estimation unit 35 determines that the average current value is abnormal.
If it is determined that the average current value is not normal (step S106/NO), the state estimation unit 35 advances the process to step S107. On the other hand, if it is determined that the average current value is normal (step S106/YES), the state estimation unit 35 advances the process to step S108.

If the process proceeds to step S107, the driving state of the brush motor 11 is estimated to be "abnormal" by the state estimation unit 35. In this case, the drive control unit 36 cuts off the power supply to the brush motor 11 (step S107).

If the process proceeds to step S108, the driving state of the brush motor 11 is estimated to be "abnormal" by the state estimation unit 35. In this case, the maximum order detection unit 34 detects the order with the maximum intensity as the maximum order from the frequency spectrum obtained by the frequency analysis unit 32 excluding the zero-order component (step S108).
Next, the state estimation unit 35 determines whether the maximum degree detected by the maximum degree detection unit 34 matches the target degree (step S109). Specifically, the state estimating unit 35 refers to the map information 41 used for estimating the rotational state and checks whether the detected maximum order matches the target order.
If it is determined that the maximum degree and the target degree match (step S109/YES), the state estimation unit 35 advances the process to step S110. On the other hand, if it is determined that the maximum degree and the target degree do not match (step S109/NO), the state estimation unit 35 advances the process to step S111.

When the process proceeds to step S110, the rotational state of the brush motor 11 is estimated to be "normal" by the state estimation unit 35. In this case, the drive control unit 36 controls the duty ratio of the PWM signal so that the rotational speed is maintained and the rotational state remains "normal" (step S110).

When the process proceeds to step S111, the state estimation unit 35 determines whether the maximum degree detected by the maximum degree detection unit 34 is the target degree +1 or the target degree −1 (step S111). When the maximum degree is the target degree +1 (step S111/+1), the state estimation unit 35 advances the process to step S112. On the other hand, if the maximum degree is the target degree -1 (step S111/-1), the state estimation unit 35 advances the process to step S113.

When the process proceeds to step S112, the rotational state of the brush motor 11 is estimated to be "high speed" by the state estimation unit 35. In this case, the drive control unit 36 controls the duty ratio of the PWM signal so that the rotational speed is lowered and the rotational state becomes "normal" (step S112).

If the process proceeds to step S113, the rotational state of the brush motor 11 is estimated to be "low speed" by the state estimation unit 35. In this case, the drive control unit 36 controls the duty ratio of the PWM signal so that the rotational speed is increased and the rotational state becomes "normal" (step S113).
Note that after step S107, step S110, step S112, and step S113, the process is repeated from step S106.

As explained above, the motor control device 1 according to the present embodiment detects the current value of the current flowing through the brush motor 11, extracts the current ripple included in the current based on the detected current value, and extracts the current ripple contained in the current based on the detected current value. The frequency spectrum of the current ripple is acquired by frequency analysis of the current ripple, the average current value of the current is calculated based on the acquired frequency spectrum, and the drive of the brush motor is controlled based on the calculated average current value.

With this configuration, the motor control device 1 according to the present embodiment calculates the average current value without using additional parts in order to perform control (drive control) using the average current value obtained by averaging the detected current values. Therefore, it is possible to prevent an increase in cost due to an increase in the number of parts.
Therefore, the motor control device 1 according to the present embodiment makes it possible to reduce the cost of control performed by detecting the current flowing through the brush motor 11.

Further, the motor control device 1 according to the present embodiment performs control based on the rotation speed of the brush motor 11 (rotation speed control) based on the map information 41. As a result, the motor control device 1 can control the rotation speed without using a sensor device (for example, a sensor magnet or a Hall sensor) for detecting the rotation speed, thereby preventing an increase in cost due to an increase in the number of parts. be able to. Further, since the motor control device 1 does not use a sensor device for detecting the rotation speed, the rotation speed can be controlled with high accuracy without being affected by sensor accuracy.

Further, in the brush motor 11, the rotation speed may vary due to the influence of external disturbances, and the maximum order may also vary. For example, when the number of rotations decreases due to the influence of disturbance, the maximum order may also decrease in accordance with the decrease in the number of rotations. For example, the maximum order detected by the maximum order detection unit 34 may decrease from the 10th order to the 9th order.
Even when the rotational speed fluctuates in this way, the motor control device 1 according to the present embodiment estimates the rotational state based on the maximum order that fluctuates in accordance with the rotational speed fluctuation. The tracked rotational state can be estimated. Thereby, the motor control device 1 according to the present embodiment can perform stable spark suppression control.

Further, according to the present embodiment, the motor control device 1 can suppress spark generation in the brush motor 11 without using additional parts for calculating the average current value, and can reduce the number of parts and cost. . This can contribute to minimizing the amount of resources used in devices equipped with the motor control device 1, so it is possible to achieve goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations by building resilient infrastructure. , promote inclusive and sustainable industrialization, and promote innovation.

The embodiments of the present invention have been described above. Note that all or part of the motor control device 1 in the embodiment described above may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the "computer system" herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, a "computer-readable recording medium" refers to a storage medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include a device that retains a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. Further, the above-mentioned program may be one for realizing a part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system. It may be realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and includes designs within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1... Motor control device, 11... Brush motor, 12... Diode, 13... MOSFET, 14... Diode, 15... Power supply, 20... Current detection part, 30... Control part, 31... Current ripple extraction part, 32... Frequency analysis part , 33... Average current value calculation section, 34... Maximum order detection section, 35... State estimation section, 36... Drive control section, 40... Storage section, 41... Map information

Claims (8)

a current detection unit that detects the current value of the current flowing through the brush motor;
a current ripple extractor that extracts a current ripple included in the current based on the detected current value;
a frequency analysis unit that obtains a frequency spectrum of the current ripple by frequency analysis of the extracted current ripple;
an average current value calculation unit that calculates an average current value of the current based on the acquired frequency spectrum;
a drive control unit that controls driving of the brush motor based on the calculated average current value;
A motor control device comprising: The average current value calculation unit calculates the average current value from the zero-order component of the frequency spectrum.
The motor control device according to claim 1. a state estimation unit that estimates a driving state of the brush motor based on the average current value;
Furthermore,
The drive control unit controls power supply to the brush motor based on the estimated drive state.
The motor control device according to claim 1 or claim 2. The state estimation unit estimates that the drive state of the brush motor is normal or abnormal based on map information indicating a correspondence between the average current value and the drive state,
The drive control unit controls to maintain power supply to the brush motor when the brush motor is in a normal driving state, and controls to maintain power supply to the brush motor when the brush motor is in an abnormal driving state. control to cut off the supply;
The motor control device according to claim 3. a maximum order detection unit that detects, as the maximum order, an order in which the signal strength of the frequency spectrum is maximum from the frequency spectrum excluding the zero-order component of the obtained frequency spectrum;
Furthermore,
The state estimation unit estimates a rotational state of the brush motor based on the detected maximum order,
The drive control unit controls the rotational speed of the brush motor based on the estimated rotational state so that the rotational speed of the brush motor becomes a target rotational speed.
The motor control device according to claim 3. The state estimation unit estimates whether a rotational state of the brush motor at the maximum order is within a range of the target rotational speed,
The drive control unit controls the rotation speed of the brush motor so that the rotation state of the brush motor at the maximum order is within the range of the target rotation speed, according to the estimation result by the state estimation unit. ,
The motor control device according to claim 5. The state estimation unit is configured to determine, based on map information indicating a correspondence relationship between the order and the rotational state, that the rotational state associated with the same order as the maximum order is the rotational state in the maximum order. It is estimated that
The motor control device according to claim 6. a current detection step in which the current detection section detects the current value of the current flowing through the brush motor;
a current ripple extraction step in which a current ripple extraction section extracts a current ripple included in the current based on the detected current value;
a frequency analysis step in which a frequency analysis unit obtains a frequency spectrum of the current ripple by frequency analysis of the extracted current ripple;
an average current value calculation step in which an average current value calculation unit calculates an average current value of the current based on the acquired frequency spectrum;
a drive control step in which a drive control unit controls the drive of the brush motor based on the calculated average current value;
A motor control method including:

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