JP2013090466A - Stepping motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stepping motor control device achieving an actuator function providing a user with reduced strangeness, while reducing effective power.SOLUTION: A stepping motor includes: a control device 10 for controlling drive of stepping motors 31-33; a mode switch control unit 11 included in the control device 10, for switching a drive mode of the stepping motors 31-33 to a normal mode allowing low torque high speed drive or a low voltage mode allowing high torque low speed drive on the basis of a power supply voltage detected by a power supply voltage detection unit 22; and an output suppression control unit 12 included in the mode switch control unit 11, for, when power supply protection conditions are established and the plurality of stepping motors 31-33 are simultaneously driven, for setting the drive mode to the low voltage mode, and executing output suppression control for setting at least a part of a low frequency output signal to an output signal having a PWM waveform.

Description

  The present invention relates to a stepping motor control device that controls driving of a stepping motor.

2. Description of the Related Art Conventionally, in a stepping motor control device that controls the driving of a plurality of stepping motors, a device that prevents a shortage of torque due to a low voltage by switching the driving mode of the stepping motor according to a power supply voltage is known (for example, Patent Documents). 1).
This conventional stepping motor control device drives the stepping motor at low torque and high speed during normal times when the power supply voltage is equal to or higher than a predetermined voltage, and drives the stepping motor at high torque and low speed at low voltage below the predetermined voltage. Torque shortage during voltage is prevented.
Furthermore, in the prior art, when driving a plurality of stepping motors at the same time, in order to prevent an adverse effect due to a decrease in driving speed, after stopping a plurality of actuators, the stepping motors are ordered in descending order of priority. It is driven one by one.

Japanese Patent No. 4660833

By the way, if a plurality of stepping motors are driven at the same time, the load on the power supply increases, and the power protection performance decreases.
Therefore, in order to protect the power supply when driving a plurality of stepping motors at the same time, when applying the above technology, all the stepping motors are temporarily stopped and driven in order from the highest priority stepping motor. The following problems arise.
That is, when a plurality of stepping motors are driven one by one in order from the one with the highest priority, the other stepping motors remain stopped until the stepping motor with the higher priority finishes moving. Therefore, the user feels uncomfortable because the function of the stopped stepping motor is not exhibited.
In addition, the stepping motor once stopped requires a large starting force at the time of restarting, and accordingly, the load on the power supply increases and the operation time also increases, leading to deterioration of the power protection performance.

  Therefore, an object of the present invention is to provide a stepping motor control device that realizes a driving state of a stepping motor that protects the power supply and does not give the user a sense of incongruity.

  To achieve the above object, the present invention provides a plurality of stepping motors, a driving power source for these stepping motors, a driving condition detecting unit including a voltage detecting unit for detecting the voltage of the driving power source, and this driving condition detecting A drive control unit for controlling the drive of the stepping motor by outputting an ON / OFF drive signal of a set frequency to the stepping motor based on an input from the unit, and included in the drive control unit in advance. When a plurality of stepping motors are driven simultaneously when a set power supply protection condition is satisfied, an ON waveform of the drive signal is formed with a PWM waveform having a frequency higher than the frequency in a part thereof, and the remaining waveform part is formed. An output suppression control unit that executes an output suppression process for forming a non-PWM waveform for suppressing the speed reduction. And a stepping motor controller according to symptoms.

In the stepping motor control device of the present invention, when a plurality of stepping motors are driven simultaneously when the power load condition is satisfied, the output suppression control unit executes the output suppression process, and the ON waveform of the drive signal is included in a part of the high-frequency PWM. A waveform is formed, and a non-PWM waveform for suppressing a decrease in speed is formed.
Therefore, since a plurality of stepping motors are driven at the same time, it is less likely to give the user a sense of discomfort than a case where the stepping motors are driven in order after stopping all of them once.
And, since part of the ON waveform of the drive signal to the stepping motor is a PWM waveform, the ON time is thinned out, so that the power load can be reduced compared to the case where the ON waveform is fully turned ON, and the stopped state Compared with the case of starting from the power supply, it is possible to reduce the power load and protect the power supply.
In addition, at this time, in order to form a non-PWM waveform that suppresses the speed reduction due to the PWM waveform in the ON waveform, the step-out due to the speed reduction or stop is compared with the case where all of the ON waveforms are PWM waveforms. Can be suppressed.

It is a block diagram which shows the stepping motor control apparatus of embodiment of this invention. It is a time chart which shows the waveform of the output signal in the normal mode and the waveform of the output signal in the low voltage mode in the stepping motor control device of the embodiment. It is a time chart explaining the inertial drive by the load at the time of an output signal stop in the stepping motor control device of an embodiment. It is a time chart which shows the waveform of the output signal when the output suppression process is performed in the stepping motor control device of the embodiment. It is a circuit block diagram which shows the structure of the part which forms the waveform of an output signal in the stepping motor control apparatus of embodiment. It is a flowchart which shows the flow of the mode switching process and output suppression process in the stepping motor control apparatus of embodiment. It is a characteristic view which shows the relationship between the drive mode characteristic and threshold value of the stepping motor control apparatus of an embodiment. It is a time chart which shows the waveform of the output signal at the time of execution of output control processing in the stepping motor control device of an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A stepping motor control apparatus according to an embodiment will be described with reference to FIGS.

  The control device (drive control unit) 10 controls driving of the plurality of stepping motors 31, 32, 33 and other actuator groups 34.

The stepping motors 31 to 33 are driven to change the opening degree of the doors 41, 42, 43 such as intake doors and mode doors in the air conditioner mounted on the vehicle. In the figure, three stepping motors 31 to 33 and doors 41 to 43 are shown, but the number of stepping motors and doors to be controlled is limited to “3” as long as the number is two or more. It is not something.
The other actuator group 34 is an actuator other than the stepping motors 31 to 33 in the air conditioner including a fan or a compressor of the air conditioner.

The control device 10 receives signals from the sensor group 21, the power supply voltage detection unit 22, and the operation unit 23. The sensor group 21 includes a passenger compartment temperature sensor, a vehicle exterior temperature sensor, a solar radiation amount sensor, and the like for the temperature environment of the passenger compartment necessary for controlling the air conditioner.
The power supply voltage detector 22 detects a power supply voltage Vde that is a voltage of the drive power supply 50 that drives the stepping motors 31 to 33 and the like.
The operation unit 23 is a part where an occupant performs setting operations such as temperature and air volume for controlling the air conditioner.

  The control device 10 controls each of the stepping motors 31 to 33 and the actuator group in order to control the air volume and the blown air temperature of the air conditioner based on the input signals from the sensor group 21, the power supply voltage detection unit 22, and the operation unit 23. 34 is driven to control the operation of the air conditioner including the opening degrees of the doors 41 to 43.

Furthermore, the control device 10 switches the driving mode of the plurality of stepping motors 31 to 33 based on the power supply voltage Vde detected by the power supply voltage detection unit 22 when controlling the driving of the plurality of stepping motors 31 to 33. A switching control unit 11 is provided.
The mode switching control unit 11 performs control to switch the driving mode of the stepping motors 31 to 33 in order to reduce the effective power when the power supply voltage Vde is lowered. This mode switching control will be described below. .

In the present embodiment, a normal mode and a low voltage mode are set as drive modes of the stepping motors 31 to 33.
The normal mode is a mode in which the stepping motors 31 to 33 are driven at a low torque and a high speed. In this normal mode, the mode switching control unit 11 outputs two-phase ON / OFF pulse signals of x and y shown in FIG. 2 when the stepping motors 31 to 33 are driven at low torque and high speed. The frequency at this time is defined as a first frequency f1. As shown in FIG. 2, the output time of the ON signal of one pulse in the normal mode is tp1.

On the other hand, in the low voltage mode, the mode switching control unit 11 drives the stepping motors 31 to 33 at high torque and low speed. In this low voltage mode, as shown in FIG. 2, the mode switching control unit 11 sends a two-phase ON / OFF pulse signal of x and y to a second frequency f2 having a frequency lower than the first frequency f1. To output. When driven in this low voltage mode, the power consumption of the stepping motors 31 to 33 is reduced compared to the normal mode. Further, as shown in FIG. 2, in the low voltage mode, the output time (wavelength) tp2 of the ON signal of one pulse in the output signal is longer than the output time tp1 of the ON signal in the normal mode.
Note that the output signals to the stepping motors 31 to 33 are not limited to the two-phase ones as shown in the figure, and three-phase, five-phase, etc. output signals are used according to the winding structure of the stepping motor. May be.

Next, the load of each stepping motor 31 to 33 will be described.
As shown in FIG. 1, loads including doors 41 to 43 are attached to the stepping motors 31 to 33, respectively. Therefore, as shown in FIG. 3, when the output signals to the stepping motors 31 to 33 are stopped at the time point Ts shown in the figure, the stepping motors 31 to 33 perform inertial driving, and the time Tina is required to completely stop. Cost. Therefore, in the normal mode and the low voltage mode, the OFF time of the ON / OFF output signal is set to a time shorter than this time Tina, and the stepping motors 31 to 33 do not stop.

Next, the output suppression control unit 12 shown in FIG. 1 will be described.
The output suppression control unit 12 executes output suppression processing when a plurality of stepping motors 31 to 33 are simultaneously driven in the above-described low voltage mode.

In this output suppression process, a part of the ON output signal in the low voltage mode is shortened by shortening the ON output time as a PWM waveform having a frequency higher than that of the second frequency f2, as shown in FIG. Further, in the present embodiment, the entire output time tp2 of the ON output in the low voltage mode is left as it is, a part thereof is a PWM waveform as described above, and the stepping motors 31 to 31 are provided at the end of the ON output signal. A non-PWM waveform portion Pa for suppressing the speed reduction of 33 is formed. In other words, in the ON output signal of one cycle in the low voltage mode, the time tp3 from the start to the preset middle is set as the PWM waveform, and the remaining time (tp2-tp3) is left as the non-PWM waveform portion Pa. ing.
That is, in the embodiment, the non-PWM waveform portion Pa is formed so that the stepping motors 31 to 33 do not step out or stop due to insufficient torque due to the PWM waveform of the ON output signal. The speed before waveform conversion is restored.
This will be described with reference to FIG. 4. When the ON output signal is thinned with a PWM waveform for a time tp3, the driving speed of the stepping motors 31 to 33 gradually decreases. Therefore, the speed of the stepping motors 31 to 33 is returned to the speed before the PWM waveform is obtained by the output of the non-PWM waveform portion Pa. The output time (tp2-tp3) of the non-PWM waveform portion Pa is set in advance to a time during which the drive speed can be restored.

A circuit configuration for performing the above-described mode switching control and output suppression processing will be described with reference to FIG.
In the part that outputs signals from the mode switching control unit 11 of the control device 10 shown in FIG. 5 to the stepping motors 31 and 32, output circuits that output two phases x and y to the stepping motors 31 and 32, respectively. 10a and 10b are provided. Further, the mode switching control unit 11 outputs an interrupt signal (INT1, INT2) for turning off the output of the output circuits 10a, 10b to the output circuits 10a, 10b, and the interrupt time of the OFF signal is switched. The output signal of the low torque high speed drive shown in FIG. 2 and the output signal of the high torque low speed drive are formed.

Returning to FIG. 5, a switch element 10c is connected to each of the output circuits 10a and 10b. When a high frequency waveform is given to the switch element 10c from the output suppression control unit 12 of the control device 10 via the circuit 10d, the ON output signals of the output circuits 10a and 10b are intermittently transmitted as shown in FIG. Pulled to form a PWM waveform. In addition, as shown in FIG. 5, the PWM waveform formation in the ON output signal in the low voltage mode by the switch element 10c is executed while the Hi output from the circuit 10f is stopped and the switch element 10e is in the OFF state. Is done. When the switch element 10e is output to Hi and the switch element 10e is in the ON state, the switch element 10c is turned OFF, and the PWM waveform in the ON output signal is not formed, and the non-PWM waveform portion Pa can be formed. .
Here, the output to the switch element 10e is triggered by the rise or fall of the aforementioned interrupt signal (INT1, INT2).
In FIG. 5, the switch elements 10c and 10e are shown connected only to the x-phase output circuit 10a, but the same configuration is also connected to the y-phase output circuit 10b. The PWM waveform is also formed in the ON output signal.

Next, the flow of mode switching by the mode switching control unit 11 and output suppression processing by the output suppression control unit 12 will be described with reference to the flowchart of FIG.
First, in step S1, the power supply voltage Vde detected by the power supply voltage detector 22 is read, and the process proceeds to the next step S2.

  In step S2, drive mode determination is performed based on the power supply voltage Vde read in step S1 and the preset drive mode characteristics shown in FIG. 7, and then the process proceeds to step S3. As shown in FIG. 7, two threshold values Vs1 and Vs2 to which hysteresis is given are set as drive mode characteristics. That is, the drive mode characteristics are set such that the drive mode is changed from the normal mode to the low voltage mode when the power supply voltage Vde decreases to become equal to or lower than the threshold value Vs1. The drive mode characteristics are set so that the drive mode is changed from the low voltage mode to the normal mode when the power supply voltage Vde rises and becomes equal to or higher than the threshold value Vs2. The drive mode characteristics may be set to a stop mode in which each of the stepping motors 31 to 33 is stopped when the power supply voltage Vde is lower than a threshold voltage lower than the threshold value Vs1, as in the conventional technique. .

In step S3, it is determined whether the drive mode determination result in step S2 is the normal mode or the low voltage mode. If it is the normal mode, the process proceeds to step S4, and if it is the low voltage mode, the process proceeds to step S5.
In step S4, which proceeds in the normal mode, when driving each of the stepping motors 31 to 33, low torque high speed driving (see FIG. 2) is performed, and one process is completed.

  On the other hand, in step S5 which proceeds in the low voltage mode, it is determined whether or not the control state of the control device 10 is a control state in which two or more (plural) stepping motors 31 to 33 are simultaneously driven. The process proceeds to step S6, and in the case of simultaneous driving, the process proceeds to step S7.

In step S6, one of the stepping motors 31 to 33 is independently driven at high torque and low speed (see FIG. 2), and then one process is terminated.
In step S7, when simultaneously driving a plurality of stepping motors 31 to 33, the output suppression process is performed, and then one process is terminated. That is, as described above, in the output suppression process, as shown in FIG. 4, the ON output signal for driving each of the stepping motors 31 to 33 at a high torque and low speed is thinned by the PWM waveform and the ON output signal Processing to leave the non-PWM waveform portion Pa at the end is performed.
Furthermore, in this embodiment, in this output suppression process, the cueing timing of the waveform of the output signal to each of the stepping motors 31 to 33 is shifted. As a result, the output timing of the non-PWM waveform portion Pa differs depending on the stepping motors 31 to 33 and is not simultaneously output. The control of the output timing is performed by shifting the timing of giving the interrupt signals (INT1, INT2) to the output circuits 10a, 10b in the control device 10.

  As described above, in the present embodiment, the condition for performing the output suppression process is that the power supply voltage Vde is lower than one of the threshold values Vs1 and Vs2, the low voltage mode is set, and the stepping motor 31 This is a case where a plurality of .about.33 are driven simultaneously. Therefore, in this embodiment, the low voltage mode is set when a preset power protection condition is satisfied.

Next, the operation of the embodiment will be described.
(Normal mode)
In the stepping motor control device according to the embodiment, when the power supply voltage Vde is larger than the threshold value Vs1 or when the power supply voltage Vde rises to the threshold value Vs2 or more from the state where the power supply voltage Vde is lower than the threshold value Vs1, the normal mode is determined in the drive mode determination in step S2 It is determined.

  When it is determined that the normal mode is selected, the stepping motors 31 to 33 are driven by the ON / OFF output signal having the frequency of the first frequency f1 shown in FIG. Low torque and high speed drive.

(Low voltage mode)
When the power supply voltage Vde is less than the threshold value Vs1 or lower than the threshold value Vs2 when rising from a lower voltage state than this, the low voltage mode is determined in the drive mode determination of step S2.

In this low voltage mode, the stepping motors 31 to 33 perform high torque low speed driving by an ON / OFF output signal having a frequency of the second frequency f2 shown in FIG. Therefore, torque shortage due to low voltage can be prevented, and occurrence of step-out due to torque shortage can be prevented.
Furthermore, in this embodiment, in this low voltage mode, the waveform of the output signal is made different between when the stepping motors 31 to 33 are driven alone and when they are driven plurally.
That is, when the stepping motors 31 to 33 are driven independently, a low voltage mode signal having an ON output signal having the wavelength (output time tp2) shown in FIG. 2 is output. In this case, since the number of stepping motors 31 to 33 to be driven is one, power consumption can be suppressed.
On the other hand, when a plurality of stepping motors 31 to 33 are driven at the same time, as shown in FIG. 8, a part of the waveform of the ON output signal at the second frequency f2 in the low voltage mode is thinned and output as a PWM waveform. Thus, by simultaneously driving the stepping motors 31 to 33, after all the stepping motors 31 to 33 are temporarily stopped, it is possible to suppress a sense of incongruity given to the user as compared with the case of sequentially driving the PWM. The power load can be reduced compared to the case where the waveform is not used.

As described above, the stepping motor control device according to the embodiment has the effects listed below.
a) In this embodiment,
A plurality of stepping motors 31 to 33;
Drive power supply 50 for these stepping motors 31-33,
A drive condition detector (21, 22, 23) including a power supply voltage detector 22 for detecting the voltage of the drive power supply 50;
Based on the input from this drive condition detection part (21,22,23), the ON / OFF drive signal of the set frequency is output with respect to the stepping motors 31-33, and the drive of the stepping motors 31-33 is controlled. A control device 10 for
When a plurality of stepping motors 31 to 33 are simultaneously driven when a preset power supply protection condition is satisfied, which is included in the control device 10, an ON waveform of the drive signal is generated, and a PWM waveform having a frequency higher than the above frequency is included in a part thereof. An output suppression control unit 12 that executes an output suppression process for forming a non-PWM waveform part Pa for suppressing a decrease in speed in the remaining waveform part,
It was set as the structure provided with.
Therefore, in the embodiment, when the stepping motors 31 to 33 are driven at the same time when the power load condition is satisfied, the output suppression control unit 12 executes the output suppression process, and the ON waveform of the drive signal is a part of the high frequency. And a non-PWM waveform for suppressing a reduction in speed.
As described above, since a plurality of stepping motors 31 to 33 are simultaneously driven, it is less likely to give the user a sense of incongruity as compared with a case in which the stepping motors 31 to 33 are all driven once after being stopped once.
Since the ON time is thinned out by using a part of the ON waveform of the drive signal to the stepping motors 31 to 33 as a PWM waveform, the power load can be reduced as compared with the case where the ON waveform is fully output. Compared with the case where the apparatus is started from the stopped state, the power load can be reduced and the drive power supply 50 can be protected.
In addition, at this time, in order to form a non-PWM waveform that suppresses the speed reduction due to the PWM waveform in the ON waveform, the step-out due to the speed reduction or stop is compared with the case where all of the ON waveforms are PWM waveforms. Can be suppressed.

b) In the embodiment, the control device 10 sets the drive mode of the stepping motors 31 to 33 based on the power supply voltage Vde detected by the power supply voltage detection unit 22 to a low torque and high speed drive by a signal output of the first frequency f1. A mode switching control unit 11 that switches between a normal mode to be driven and a low voltage mode in which high torque and low speed driving is performed by a signal output of a second frequency f2 lower than the first frequency f1;
The output suppression control unit 12 sets the drive mode as the low voltage mode when the power supply protection condition is satisfied.
Therefore, the output suppression control unit 12 executes output suppression processing when driving the plurality of stepping motors 31 to 33 when the power supply voltage Vde decreases and the drive mode is set to the low voltage mode, and the drive power supply 50 Can be protected.

c) The output suppression control unit 12 performs timing control so that the non-PWM waveform portions Pa in the output signals for the plurality of stepping motors 31 to 33 are not simultaneously output.
Therefore, compared with the case where the non-PWM waveform portion Pa is output at the same time, it is possible to further reduce the power load and protect the drive power supply 50.

d) In forming the PWM waveform portion, the output suppression control unit 12 sets a part of the ON output waveform as the PWM waveform while keeping the output time tp2 of the original ON output waveform of the high torque low speed driving as it is. I made it.
For this reason, it is not necessary to change the output frequency to the output circuits 10a and 10b between the output suppression process and the non-output suppression process, and the control can be simplified and the configuration of the control device 10 can be simplified.

e) In this embodiment, when forming the PWM waveform portion, in order to form an output waveform of a predetermined period to the stepping motors 31 to 33, it is formed using the timing of the interrupt signal forming the OFF state. I did it.
For this reason, it is easier to form an output signal as compared with the case where a signal having a different period is newly formed and a part thereof is a PWM waveform, and the control device 10, the mode switching control unit 11, the output suppression control unit Twelve configurations can be simplified.

  f) In the present embodiment, the non-PWM waveform portion Pa is set at the end of the ON output signal. With such ON / OFF switching, the torque of the stepping motors 31 to 33 is reduced. For this reason, compared with the non-PWM waveform portion Pa set at the start point or the middle of the ON output signal, torque fluctuation during the output of the ON output signal can be suppressed, and the drive characteristics are more preferable. .

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the embodiment, an example in which a stepping motor is applied to an air conditioner has been described. However, the scope of application of the present invention is not limited to an air conditioner as long as the apparatus uses a stepping motor.

  In the embodiment, when the non-PWM waveform portion is formed, the position where the non-PWM waveform portion is formed in the ON output signal is not limited to the end, and may be formed at the start end or the middle of the ON output signal.

In the output suppression control unit, the power protection condition set in advance is the low voltage mode, but the power protection condition is not limited to this.
For example, the power supply protection condition is when the power supply voltage Vde is equal to or lower than the second threshold set to a voltage lower than the threshold Vs1 for switching between the low voltage mode and the normal mode, or lower than the second threshold. May be estimated. In this case, similarly to the embodiment, a PWM waveform and a non-PWM waveform are formed in the output signal of the high torque low speed drive.
The power source protection condition is that when a plurality of stepping motors are driven in a situation where the power source voltage Vde is between the threshold value Vs1 and the threshold value Vs2 or is equal to or higher than the threshold value Vs2 and a plurality of stepping motors are simultaneously driven in the normal mode, Furthermore, it may be a case where it is predicted that the power supply voltage Vde will be lower than a preset threshold value by driving another actuator. In this case, similarly to the embodiment, the PWM output and the non-PWM waveform may be formed in the ON output signal of the high torque low speed drive. However, unlike the embodiment, the ON output of the low torque high speed drive is different. A PWM waveform and a non-PWM waveform may be formed in the signal. Alternatively, a PWM waveform and a non-PWM waveform may be formed in the waveform of an ON output signal such as intermediate torque intermediate speed drive different from high torque low speed drive and low torque high speed drive.

10 Control device (drive controller)
11 Mode switching control unit 12 Output suppression control unit 21 Sensor group (drive condition detection unit)
22 Power supply voltage detector (drive condition detector)
23 Operation unit (drive condition detection unit)
31 Stepping motor 32 Stepping motor 33 Stepping motor 50 Driving power supply f1 First frequency f2 Second frequency Pa Non-PWM waveform portion

Claims (3)

Multiple stepping motors,
Driving power for these stepping motors,
A drive condition detector including a voltage detector for detecting the voltage of the drive power supply;
A drive control unit for controlling the driving of the stepping motor by outputting an ON / OFF driving signal having a set frequency to the stepping motor based on an input from the driving condition detection unit;
When a plurality of stepping motors are driven simultaneously when a preset power protection condition is established, the drive signal includes an ON waveform of the drive signal, and a PWM waveform having a frequency higher than the frequency as a part thereof. And an output suppression control unit that executes an output suppression process for forming a non-PWM waveform for suppressing a decrease in speed in the remaining waveform portion,
A stepping motor control device comprising: The drive control unit, based on the power supply voltage detected by the voltage detection unit, sets the drive mode of the stepping motor to a normal mode in which a low-torque high-speed drive is performed by a signal output of a first frequency, and from the first frequency Also has a mode switching control unit that switches to a low voltage mode that drives high torque and low speed by low frequency signal output,
2. The stepping motor control device according to claim 1, wherein the output suppression control unit is when the preset power supply protection condition is satisfied when the drive mode is set to the low voltage mode.   3. The output suppression control unit performs timing control so that the non-PWM waveform portion in the output signal is not simultaneously output to the stepping motor that is driven simultaneously. The stepping motor control device described.