JP2022110849A - Motor control device and motor control method - Google Patents

Abstract

To reliably execute each interruption processing based on detection information of each of a rising edge and a falling edge of a PWM signal even if a period of the PWM signal is accelerated.SOLUTION: The present invention relates to a motor control device for controlling a motor. The motor control device includes: an edge detection unit for detecting a rising edge and a falling edge of a PWM signal for motor control; a first storage unit for storing detection information of the rising edge detected by the edge detection unit; a second storage unit that is different from the first storage unit and stores detection information of the falling edge detected by the edge detection unit; a first processing unit for executing first interruption processing based on the detection information of the rising edge stored in the first storage unit; and a second processing unit for executing second interruption processing based on the detection information of the falling edge stored in the second storage unit.SELECTED DRAWING: Figure 2

Description

The present invention relates to a motor control device and a motor control method, and more particularly to a motor control device and a motor control method for controlling a motor based on rising edges and falling edges of PWM (Pulse Width Modulation) signals for motor control.

Detect the rising edge of the PWM signal, measure the ON time from one rising edge to the next rising edge, and output the ratio of the total ON time for two PWM cycles to the time for two PWM cycles as a duty ratio. A technique is known (see, for example, Patent Document 1).

JP 2020-31374 A

If the falling edge of the PWM signal occurs immediately after the rising edge of the PWM signal is detected, there is a risk that the detection information of the rising edge will be overwritten by the detection information of the falling edge. Similarly, if the PWM signal rises immediately after the falling edge of the PWM signal is detected, the falling edge detection information may be overwritten by the rising edge detection information. If such overwriting is performed, there is a possibility that each interrupt processing based on detection information of the rising edge and falling edge of the PWM signal cannot be realized in a desired manner. Such a problem becomes conspicuous when the cycle (input frequency) of the PWM signal becomes faster.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to ensure that each interrupt processing based on detection information of the rising edge and falling edge of the PWM signal is performed even if the period of the PWM signal is increased. The purpose is to be able to run

In order to solve the above problem, one aspect of the present invention provides a motor control device that controls a motor,
an edge detection unit that detects rising edges and falling edges of a PWM signal for motor control;
a first storage unit that stores detection information of the rising edge detected by the edge detection unit;
a second storage unit, which is separate from the first storage unit and stores detection information of the falling edge detected by the edge detection unit;
a first processing unit that executes a first interrupt process based on the rising edge detection information stored in the first storage unit;
a second processing unit that executes a second interrupt process based on the falling edge detection information stored in the second storage unit;
A motor controller is provided comprising:

According to the present invention, even if the period of the PWM signal is increased, it is possible to reliably execute each interrupt process based on detection information of each of the rising edge and the falling edge of the PWM signal.

1 is a perspective view showing the configuration of an apparatus using the brushless motor of this embodiment; FIG. 1 is a block diagram showing a main part of a configuration of a control device for a brushless motor; FIG. FIG. 4 is an explanatory diagram of the operation of the control device of the embodiment; FIG. 10 is an explanatory diagram of operations according to a comparative example; FIG. 4 is an explanatory diagram of a level time filter of this embodiment; FIG. 10 is an explanatory diagram of a level filter according to a comparative example;

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the following, first, an overview of the configuration of a device using the brushless motor M will be described, and then a control device 10 (an example of a motor control device) for the brushless motor M will be described.

FIG. 1 is a perspective view showing the configuration of an apparatus using the brushless motor M of this embodiment.

As shown in FIG. 1, the brushless motor M of this embodiment is used, for example, as a part (that is, a fan motor) of a device that drives a suction-type fan unit F (FIG. 1). Note that the brushless motor M is, for example, a three-phase motor. The fan unit F can send air to an object to be cooled (for example, a radiator) by being rotated by the rotational driving force of the brushless motor M. As shown in FIG.

FIG. 2 is a block diagram showing a main part of the configuration of the control device 10 for the brushless motor M. As shown in FIG.

As shown in FIG. 2, the control device 10 includes an edge detection unit 12, a first storage unit 14, a rising interrupt processing unit 16 (an example of a first processing unit), a second storage unit 18, a falling interrupt and a processing unit 20 (an example of a second processing unit).

The edge detection unit 12 is in the form of a hardware edge detection circuit, and a PWM signal for motor control is input to the edge detection unit 12 . The PWM signal for motor control may be generated by an ECU (Electronic Control Unit) higher than control device 10 or may be generated within control device 10 . The PWM signal for motor control is a signal representing a target value for driving the brushless motor M, and the duty (ratio of ON time per single cycle) changes within a predetermined duty range. For example, a high duty state corresponds to a high output state or a high rotation state of the brushless motor M, and a low duty state corresponds to a low output state or a low rotation state of the brushless motor M.

A PWM signal is generated, for example, based on a carrier signal (for example, a triangular wave signal) having a predetermined frequency. In this case, the higher the predetermined frequency, the shorter the period of the PWM signal (that is, the higher the speed).

The edge detection unit 12 detects rising edges and falling edges of PWM signals for motor control. A rising edge of the PWM signal occurs due to a change when the level (output level) of the PWM signal changes from Low level to High level. A falling edge of the PWM signal occurs due to the change when the level (output level) of the PWM signal changes from High level to Low level.

In this embodiment, the edge detection unit 12 detects the rising edge and falling edge of the PWM signal for motor control in such a manner that the noise signal is removed by the level time filter.

Specifically, the edge detection unit 12 detects that the PWM signal rises to a high level, and the duration of the high level after the rise (that is, the ON time) is the filter setting time ΔT1 (first filter setting time). example), the rising edge associated with the rising is detected. The filter setting time ΔT1 is a suitable value set at the time of design, and is set shorter than the ON time related to the minimum duty within the duty range to be used, for example.

Further, the edge detection unit 12 determines that the PWM signal has a fall to the Low level, and the duration of the Low level after the fall (that is, the off time) is the filter setting time ΔT2 (an example of the second filter setting time). ), the falling edge associated with the falling edge is detected. The filter setting time ΔT2 is a suitable value set at the time of designing, and is set shorter than the OFF time related to the maximum duty within the duty range to be used, for example. Note that the filter setting time ΔT1 and the filter setting time ΔT2 may be the same.

The first storage unit 14 is implemented by, for example, a register. The first storage unit 14 stores detection time information (an example of rising edge detection information) of the rising edge detected by the edge detection unit 12 . The rising edge detection time information stored in the first storage unit 14 may be updated each time the edge detection unit 12 detects a new rising edge.

The second storage unit 18 is implemented by, for example, a register. However, the second storage section 18 is different from the first storage section 14 . The second storage unit 18 stores detection time information (an example of falling edge detection information) of the falling edge detected by the edge detection unit 12 . The falling edge detection time information stored in the second storage unit 18 may be updated each time the edge detection unit 12 detects a new falling edge.

The start-up interrupt processing unit 16 is implemented, for example, by the CPU executing a program. When the edge detection unit 12 detects a rising edge, the rising interrupt processing unit 16 executes rising interrupt processing based on the rising edge detection time information stored in the first storage unit 14 . The contents of the rising edge interrupt processing include, for example, storing rising edge detection time information from the first storage unit 14 to software processing variables.

The falling edge interrupt processing unit 20 is implemented by, for example, a CPU executing a program. When a falling edge is detected by the edge detecting unit 12, the falling interrupt processing unit 20 executes falling interrupt processing based on the falling edge detection time information stored in the second storage unit 18. . The falling edge interrupt processing includes, for example, storing falling edge detection time information from the second storage unit 18 to software processing variables.

Next, with reference to FIG. 3 and subsequent figures, the effect of the control device 10 of this embodiment will be described while comparing it with a comparative example.

FIG. 3 is an explanatory diagram of the operation of the control device 10 of this embodiment. Time is plotted on the horizontal axis. 2 shows the time series of the states in the storage unit 18 and the processing timings of the rising interrupt processing unit 16 and the falling interrupt processing unit 20 .

FIG. 4 is an explanatory diagram of the operation according to the comparative example, where the horizontal axis represents time, and from the top, the time-series waveform of the PWM signal, the time-series of the states in the edge time information storage unit (not shown), and the , processing timings of a rising interrupt processing unit (not shown) and a falling interrupt processing unit (not shown).

The comparative example differs from the present embodiment in that an edge time information storage section having only one storage area is used instead of the first storage section 14 and the second storage section 18 .

As shown in FIG. 4, in the case of the comparative example, when a rising edge of the PWM signal occurs at time t1, time information of the rising edge (in FIG. 4, " Rise time information (k)”) is stored. In this example, after time t1, the falling edge of the PWM signal occurs at time t2 up to time t11 at which the rising interrupt process executed in response to the detection of the rising edge is started. In this case, as indicated by an arrow 301, time information of a falling edge (in FIG. fall time information (k)”) is stored. After time t2, the rising interrupt process is started at time t11. Note that such a time delay (that is, the time from when the rising edge is detected to when the rising interrupt process starts) is caused by software processing. That is, from the detection of the rising edge to the storage of the time information of the rising edge, hardware processing by the edge detection unit 12 can be realized with a relatively small delay (see arrow 310 in FIG. 4). to the start of the rising interrupt processing, software processing by the rising interrupt processing unit 16 causes a relatively large delay (hereinafter also referred to as “delay until interrupt processing”). Such a delay until interrupt processing is the same for the falling edge (see arrow 311 in FIG. 4).

In the example shown in FIG. 4, in the rising interrupt process started at time t11, when accessing the edge time information storage unit to refer to the time information of the rising edge (see arrow 320' in FIG. 4) , the time information of the rising edge in the edge time information storage unit has been overwritten with the time information of the falling edge at time t2. In this case, there is a possibility that the startup interrupt processing cannot be realized in a desired manner. Such a problem also occurs in the trailing edge interrupt processing.

As described above, in the comparative example, there is a possibility that the time information in the edge time information storage unit is updated (overwritten) by the start of the rising edge interrupt processing or the falling edge interrupt processing due to the delay until the interrupt processing. be. Such possibility increases as the period of the PWM signal becomes shorter (that is, the speed is increased).

On the other hand, according to the present embodiment, as described above, the first storage section 14 and the second storage section 18 are provided separately, so that the rising edge time information is overwritten by the falling edge time information. or the time information of the falling edge is overwritten by the time information of the rising edge. As a result, according to this embodiment, even if a falling edge or a rising edge occurs before the start of the rising interrupt process or the falling interrupt process due to the delay until the interrupt process, as in the comparative example, The problems described above do not occur.

Specifically, in the case of this embodiment, when a rising edge of the PWM signal occurs at time t1, as indicated by an arrow 300, the time information of the rising edge (in FIG. time information (k)”) is stored. Note that when a level time filter is used in the edge detection unit 12, the processing of storing the time information of the rising edge in the first storage unit 14 may be slightly delayed (see FIG. 5), but here the filter setting time ΔT1 and the filter setting time ΔT2 are assumed to be sufficiently small. In this example, after time t1, the falling edge of the PWM signal occurs at time t2 up to time t11 at which the rising interrupt process executed in response to the detection of the rising edge is started. In this case, as indicated by an arrow 301, the second storage unit 18 stores the time information of the falling edge (abbreviated as "falling time information (k)" in FIG. 3) related to time t2.

In the case of this embodiment, in the rising interrupt process started at time t11 after time t2, when the first storage unit 14 is accessed in order to refer to the time information of the rising edge (arrow in FIG. 3). 320), the rising edge time information in the first storage unit 14 is still retained. In this case, rising interrupt processing can be realized in a desired manner based on the time information of the rising edge. This also applies to the trailing edge interrupt processing.

In this manner, according to the present embodiment, even if the period of the PWM signal is increased, it is possible to reliably execute each interrupt processing based on the detection time information of each of the rising edge and falling edge of the PWM signal. . In other words, according to this embodiment, it is possible to speed up the period of the PWM signal. For example, it is also possible to handle relatively high input frequencies from 1000 Hz to 4000 Hz. As a result, the versatility of the control device 10 can be enhanced even when the specifications of the source of the PWM signal (for example, an upper ECU) are diversified.

FIG. 5 is an explanatory diagram of the level time filter in the control device 10 of the present embodiment. Time is plotted on the horizontal axis. A time series of the states within and a time series of the states within the second storage unit 18 are shown. Note that FIG. 5 shows a case where the filter setting time ΔT1 and the filter setting time ΔT2 (both not shown) are set longer than those in FIG. 3 for explaining the level time filter.

A filter clock is a signal used to implement a level time filter, and is a pulse signal that turns on/off with a period sufficiently smaller than the period of the PWM signal. In this case, for example, the above filter setting time ΔT1 and filter setting time ΔT2 may be managed by the count number of filter clocks.

FIG. 6 is an explanatory diagram of a level filter according to a comparative example, in which the horizontal axis represents time, the upper side 601 shows a normal judgment mode, the lower side 602 shows an undesirable judgment mode, and the upper side 601 and the lower side 602 shows the time-series waveform of the PWM signal and the time-series of the previous edge detection polarity in order from the top.

In the case of the level filter, after an edge switching interrupt occurs, the PWM signal is read to confirm the current signal level. At this time, when the current signal level is "High", a rising edge is detected when the previous edge detection polarity is falling. When the current signal level is "Low", the falling edge is detected when the previous edge detection polarity is rising.

In the case of such a level filter, when the cycle of the PWM signal is shortened (that is, speeded up), the possibility of erroneously determining a normal rising edge or falling edge (that is, not a noise signal) as noise increases.

Specifically, for example, in the upper part 601 of FIG. 6, first, a falling edge is detected at time t61, and edge switching interrupt processing is generated. In this case, edge switching by the level filter is confirmed at time t62. In this case, since the PWM signal level is "Low" and the falling edge is detected, the previous edge detection polarity is "rising", so that the level filter is passed. However, in the lower part 602 of FIG. 6, the PWM signal level is "High" and the previous edge detection polarity is "rising" with respect to detection of the rising edge, so it is determined that the signal level has not changed before and after the edge switching. That is, in this case, the falling edge occurring at time t61 and the rising edge occurring at time t62 are erroneously determined as noise.

On the other hand, according to the present embodiment, as described above, unlike the level filter according to the comparative example, the level time filter is used, so that the problems occurring in the comparative example can be resolved.

Specifically, according to this embodiment, as described above, the edge detection unit 12 detects a rising edge or a falling edge without referring to the previous edge detection polarity. Therefore, even if a PWM signal such as the one on the lower side 602 in FIG. 6 is generated, as long as the OFF time (see ΔT3 in FIG. 6) exceeds the filter set time ΔT2, the falling edge at time t61 is generated. can be detected. Therefore, it is possible to prevent erroneous detection of a fall in the level of the PWM signal caused by a noise signal in which the OFF time is equal to or less than the filter set time ΔT2 as a falling edge. A level drop of the PWM signal that shortens the target can be appropriately detected as a falling edge. The same is true for rising edges.

For example, in the example shown in FIG. 5, the change to the high level of the PWM signal generated at time t1 is detected as a rising edge when the subsequent ON time exceeds the filter setting time ΔT1. As a result, the time information of the previous rising edge (abbreviated as “rising time information (k−1)” in FIG. 5) in the first storage unit 14 is changed to the time information of the rising edge at time t1 ( is overwritten with "rising time information (k)"). Further, in the example shown in FIG. 5, the change to the Low level of the PWM signal that occurs at time t2 is detected as a falling edge because the subsequent OFF time exceeds the filter set time ΔT2. As a result, the time information of the previous falling edge (abbreviated as “falling time information (k−1)” in FIG. 5) in the second storage unit 18 is changed to the time information of the falling edge at time t2. (abbreviated as “falling time information (k)” in FIG. 5).

In the example shown in FIG. 5, the change to the high level of the PWM signal generated at time t3 is such that the subsequent ON time (the time from time t3 to time t4) does not exceed the filter set time ΔT1, so noise is determined as

In this manner, according to the present embodiment, by using the level time filter, even when the period of the PWM signal is shortened (that is, the speed is increased), errors due to rising and falling edges of the PWM signal caused by noise can be eliminated. The rising edge and falling edge of a normal PWM signal can be accurately detected while reducing the possibility of determination.

In this embodiment, the storage (storage) of the edge detection time information in the first storage unit 14 or the second storage unit 18 is delayed by the filter setting time, but a constant delay time always occurs for both edges. , does not affect the time difference between edges.

By the way, the fan unit F shown in FIG. 1 is arranged in the engine room (not shown) of the vehicle. In the engine room of a vehicle, noise due to various electromagnetic waves is likely to occur. In this regard, the control device 10 according to the present embodiment implements noise countermeasures as described above, so that highly reliable operation can be realized even under such a severe environment in the engine room.

Further, according to the present embodiment, as described above, the reliability of control can be improved, and power saving can be achieved in the control of the brushless motor M. FIG. In this way, we can contribute to the promotion of carbon-free electricity supply. access to climate change” and Goal 13 “Take urgent action to combat climate change and its impacts”.

Although the embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or more of the constituent elements of the above-described embodiments.

In addition, the following additional remarks will be disclosed with respect to the above examples.

[Appendix 1]
In a motor control device (10) for controlling a motor,
an edge detection unit (12) for detecting rising edges and falling edges of PWM signals for motor control;
a first storage unit (14) for storing detection information of rising edges detected by the edge detection unit;
a second storage unit (18) which is separate from the first storage unit and stores detection information of the falling edge detected by the edge detection unit;
a first processing unit (16) that executes a first interrupt process based on the rising edge detection information stored in the first storage unit;
a second processing unit (20) that executes a second interrupt process based on the falling edge detection information stored in the second storage unit;
A motor controller comprising:

According to the configuration of Supplementary Note 1, the first storage section for storing rising edge detection information and the second storage section for storing falling edge detection information are separately provided. As a result, even if the period of the PWM signal is increased, the rising edge detection information in the first storage unit may be overwritten with the falling edge detection information before being used in the first interrupt process. Also, it is possible to reduce the possibility that the falling edge detection information in the second storage unit is overwritten with the rising edge detection information before being used in the second interrupt process. Therefore, even if the period of the PWM signal is increased, it is possible to obtain a motor control device that can reliably execute each interrupt process based on detection information of each of the rising edge and the falling edge of the PWM signal.

[Appendix 2]
When the PWM signal rises and the level duration after the rise exceeds a first filter setting time (ΔT1), the first storage unit stores detection information of the rising edge related to the rise. 1. The motor control device according to claim 1, wherein the motor control device stores:

According to the configuration of appendix 2, even if the PWM signal rises due to noise, as long as the level duration after the rise does not exceed the first filter setting time, the detection information of the rising edge related to the rise is not stored in the first storage unit. This reduces the possibility that the first interrupt process is executed due to the rise of the PWM signal due to noise.

[Appendix 3]
The second storage unit, when there is a fall of the PWM signal and the level duration after the fall exceeds a second filter setting time (ΔT2), stores the fall related to the fall. 3. The motor control device according to appendix 1 or appendix 2, wherein edge detection information is stored.

According to the configuration of appendix 3, even if the PWM signal falls due to noise, as long as the level duration after the fall does not exceed the second filter setting time, the fall related to the fall Edge detection information is not stored in the second storage unit. This reduces the possibility that the second interrupt process is executed due to the fall of the PWM signal due to noise.

[Appendix 4]
3. The motor control device according to any one of appendices 1 to 3, wherein the motor is a brushless motor (M) for a fan unit (F) arranged in an engine room of a vehicle.

According to the configuration of Supplementary Note 4, coupled with speeding up the period of the PWM signal, it is possible to realize high performance of the brushless motor for the fan unit. In addition, by combining with the configuration of Supplementary Note 3, it is possible to ensure robust performance of the brushless motor for the fan unit even in an engine room where noise is likely to occur.

[Appendix 5]
In a motor control method for controlling a motor,
an edge detection step of detecting rising edges and falling edges of PWM signals for motor control;
a step of storing detection information of the rising edge detected by the edge detection step in a first storage unit (14);
a step of storing detection information of the falling edge detected by the edge detection step in a second storage section (18) different from the first storage section;
executing a first interrupt process based on the rising edge detection information stored in the first storage unit;
executing a second interrupt process based on the falling edge detection information stored in the second storage unit;
A motor control method comprising:

According to the configuration of Supplementary Note 5, the rising edge detection information and the falling edge detection information are stored in separate first storage units and second storage units, respectively. As a result, even if the period of the PWM signal is increased, the rising edge detection information in the first storage unit may be overwritten with the falling edge detection information before being used in the first interrupt process. Also, it is possible to reduce the possibility that the falling edge detection information in the second storage unit is overwritten with the rising edge detection information before being used in the second interrupt process. Therefore, even if the period of the PWM signal is increased, a motor control method can be obtained that can reliably execute each interrupt processing based on detection information of each of the rising edge and the falling edge of the PWM signal.

10 Control Device 12 Edge Detection Section 14 First Storage Section 16 Rise Interrupt Processing Section 18 Second Storage Section 20 Fall Interrupt Processing Section F Fan Unit M Brushless Motor

Claims (5)

In a motor control device that controls a motor,
an edge detection unit that detects rising edges and falling edges of a PWM signal for motor control;
a first storage unit that stores detection information of the rising edge detected by the edge detection unit;
a second storage unit, which is separate from the first storage unit and stores detection information of the falling edge detected by the edge detection unit;
a first processing unit that executes a first interrupt process based on the rising edge detection information stored in the first storage unit;
a second processing unit that executes a second interrupt process based on the falling edge detection information stored in the second storage unit;
A motor controller comprising: The first storage unit stores detection information of the rising edge related to the rising when the PWM signal rises and the level duration after the rising exceeds the first filter setting time. A motor controller according to claim 1. The second storage unit detects the falling edge associated with the fall when the PWM signal falls and a level duration after the fall exceeds a second filter setting time. 3. A motor controller as claimed in claim 1 or claim 2, which stores information. 4. The motor control device according to claim 1, wherein said motor is a brushless motor for a fan unit arranged in an engine room of a vehicle. In a motor control method for controlling a motor,
an edge detection step of detecting rising edges and falling edges of PWM signals for motor control;
a step of storing detection information of the rising edge detected by the edge detection step in a first storage unit;
a step of storing detection information of the falling edge detected by the edge detection step in a second storage unit different from the first storage unit;
executing a first interrupt process based on the rising edge detection information stored in the first storage unit;
executing a second interrupt process based on the falling edge detection information stored in the second storage unit;
A motor control method comprising:

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