JP2007124839A - Abnormality detector and motor controller therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detector and a motor controller therewith, capable of improving the reliability in detecting abnormalities and minimizing damages to a motor. <P>SOLUTION: This abnormality detector for detecting some abnormality of a DC motor 21, in which the rotational speed is controlled by a switching system, is installed with a pulse duration detector 3, which obtains a control pulse signal used in controlling the DC motor 21 and determines whether the pulse duration of the control pulse signal is beyond the standard pulse duration. Preferably, the DC motor 21 is controlled by using a switching device 13 for generating a control pulse signal by switching and a feedback device for adjusting the time interval of switching by the switching device, based on the control pulse signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality detection device that detects an abnormality of a motor and a motor control device using the abnormality detection device.

  Conventionally, motors (motors) have played an important role in various devices such as home appliances, automobiles, medical devices, and measuring devices. In these devices, if an abnormal operation occurs, an excessive load is applied to the built-in motor, and the motor may be abnormal. In addition, these devices cannot function in most cases when an abnormality occurs in the motor.

  For example, a centrifuge used in blood tests or the like includes a motor for rotating a rotor on which a specimen is mounted. In a centrifuge, if the rotor is rotated with the sample mounting position biased and the rotation balance is poor, or if the rotor is rotated with too much or too little sample loaded, Vibration may occur. Further, in a washing machine, if the laundry is unevenly distributed in the rotating tub, a large vibration may occur when performing a dehydration operation. If the operation of the motor is continued in a state where such a large vibration is generated, an abnormality occurs in the motor.

In order to prevent such an abnormality of the motor, various abnormality detections have conventionally been performed in devices equipped with a motor. For example, in Patent Document 1, when a motor for a washing machine is driven by vector control, a q-axis current that varies according to the generated torque of the motor is detected, and the motor is generated based on the detected q-axis current. An abnormality is detected.
JP 2002-360970 A

  However, when the abnormality detection method described in Patent Document 1 is adopted, the configuration of the motor, the control circuit, and the like becomes complicated, causing a problem such as an increase in device cost. In addition, the abnormality detection method described in Patent Document 1 has a problem that it can be applied only to an AC motor.

  An object of the present invention is to provide an abnormality detection device that solves the above problems, can detect an abnormality occurring in a motor with a simple configuration, and at a low cost, and a motor control device using the abnormality detection device.

  In order to achieve the above object, an abnormality detection apparatus according to the present invention is an abnormality detection apparatus for detecting an abnormality of a motor whose rotational speed is controlled by a switching method, and obtains a control pulse signal used for controlling the motor. And a pulse width detector for determining whether or not a pulse width of the control pulse signal exceeds a reference pulse width.

  In order to achieve the above object, a motor control device according to the present invention is a motor control device that controls the number of rotations of a motor by a switching method, and that generates a control pulse signal used for controlling the motor by switching. And a pulse width detector that acquires the control pulse signal and determines whether or not the pulse width of the control pulse signal exceeds a reference pulse width.

  As described above, in the present invention, it is determined whether or not the pulse width of the control pulse signal exceeds a certain value. Therefore, according to the present invention, it is possible to detect a motor abnormality with a simple configuration, and as a result, it is possible to suppress an increase in cost.

  An abnormality detection device according to the present invention is an abnormality detection device that detects an abnormality of a motor whose rotation speed is controlled by a switching method, acquires a control pulse signal used for controlling the motor, and obtains the control pulse signal. A pulse width detector for determining whether or not the pulse width exceeds the reference pulse width.

  The motor control device according to the present invention is a motor control device that controls the number of rotations of the motor by a switching method, a switching unit that generates a control pulse signal used for controlling the motor by switching, and the control And a pulse width detection unit that acquires a pulse signal and determines whether or not the pulse width of the control pulse signal exceeds a reference pulse width.

  In the abnormality detection device and the motor control device according to the present invention, the pulse width detection unit includes an integration circuit and a comparator, and the integration circuit smoothes the control pulse signal and generates a comparison signal. The comparator compares the voltage level of the comparison signal with the voltage level of the reference signal. When the voltage level of the comparison signal is greater than the voltage level of the reference signal, the pulse width of the control pulse signal is It is preferable to output an error signal indicating that the predetermined reference pulse width is exceeded. According to this aspect, the operator of the device can immediately take appropriate measures when an excessive load is applied to the motor.

  Furthermore, in the abnormality detection device and the motor control device according to the present invention, the pulse width detection unit includes an integration circuit, an A / D converter, and a calculation unit, and the integration circuit includes the control pulse signal. To generate a comparison signal, the A / D converter converts the comparison signal into a digital signal, the arithmetic means compares the count number of the digital signal with a reference count number, and the digital signal It is also preferable to output an error signal indicating that the pulse width of the control pulse signal exceeds the predetermined reference pulse width when the count number is greater than the reference count number. Also in this aspect, the operator of the device can immediately take an appropriate measure when an excessive load is applied to the motor.

  Further, in the abnormality detection device and the motor control device according to the present invention, when the time from the rise to the fall of the pulse of the control pulse signal is measured and the measured time is longer than the reference time, the control It is also preferable to output an error signal indicating that the pulse width of the pulse signal for use exceeds the reference pulse width. Also in this aspect, the operator of the device can immediately take an appropriate measure when an excessive load is applied to the motor.

  Furthermore, in the abnormality detection device and the motor control device according to the present invention, the pulse width detection unit is configured to control the motor when the pulse width of the control pulse signal exceeds the reference pulse width. It is also preferable to cut off the supply of the pulse signal. According to this aspect, the motor can be automatically stopped when an excessive load is applied to the motor.

  The motor control device according to the present invention may further include a feedback unit that adjusts a switching time interval by the switching unit based on the control pulse signal.

(Embodiment 1)
Hereinafter, the abnormality detection device and the motor control device according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating an example of an abnormality detection device and a motor control device according to Embodiment 1 of the present invention. FIG. 2 is a circuit diagram showing an example of a specific circuit configuration of the motor control device shown in FIG. FIG. 3 is a diagram illustrating how the pulse width of the control pulse signal changes according to the load of the motor. FIG. 4 is a diagram illustrating a control pulse signal input to the integration circuit constituting the pulse width detection unit and a comparison signal output from the integration circuit.

  As shown in FIG. 1, the motor control device 1 according to the first embodiment controls the rotational speed of a DC motor (DC motor) 21 by a method called a switching method or a chopper method. As shown in FIG. 1, the motor control device 1 includes an abnormality detection device 2 for detecting an abnormality of the DC motor 21.

  The motor control device 1 further includes an oscillating unit 12, a switching unit 13, and a feedback unit 14. A power supply 12 is connected to the switching unit 13. The switching unit 13 uses the input signal generated by the starting unit 12 and the power signal from the power source 12 to generate a control pulse signal used for controlling the rotational speed of the DC motor by switching. The control pulse signal output from the switching unit 13 is smoothed by the diode 16 and the capacitor 16, becomes a desired DC voltage, and then applied to the DC motor 21.

  In the first embodiment, as shown in FIG. 2, the switching unit 13 is configured by a PWM signal generation circuit including a switching element such as a thyristor or a power FET, and is controlled by a PWM (Pulse Width Modulation) method. A pulse signal is generated. The oscillating unit 12 generates an input signal that determines the pulse width (duty ratio) of the control pulse signal, and inputs this to the PWM signal generation circuit of the switching unit 13.

  However, as shown in FIG. 2, the input signal generated by the start unit 12 is input to the switching unit 13 via the feedback unit 14 in order to adjust the duty ratio by the feedback unit 14 described later. Although not shown, a sawtooth wave or a triangular wave is also input to the PWM signal generation circuit of the switching unit 13.

  The feedback unit 14 adjusts the switching time interval by the switching unit 13 based on the output control pulse signal. In the first embodiment, the feedback unit 14 controls the control pulse signal so that the voltage applied to the DC motor 21 is constant, that is, the rotation speed of the DC motor 21 is a set value. The duty ratio is adjusted. Specifically, as shown in FIG. 2, the duty ratio is adjusted by changing the voltage level of the input signal generated by the starter 12.

  For example, in the case where the DC motor 21 is used to drive the rotor of the centrifugal separator, if an abnormality such as contact of an object with the rotor or eccentricity of the rotation shaft of the rotor occurs, the abnormality occurs in the DC motor 21. Compared with the case where it is not, it takes a big load. At this time, since it is necessary to increase the electric power supplied to the motor 21 in order to keep the rotation speed constant, the feedback unit 14 shortens the switching time interval and sets the duty of the control pulse as shown in FIG. Increase the ratio (pulse width). On the other hand, when the load is small, the power supplied to the motor can be small. Therefore, as shown in FIG. 3, the feedback unit 14 increases the switching time interval and sets the duty ratio (pulse width) of the control pulse. Make it smaller.

  The abnormality detection device 2 detects an abnormality of the DC motor 21 by utilizing the characteristic that the pulse width of the control pulse signal changes according to the load applied to the DC motor 21. The abnormality detection device 2 includes a pulse width detector 3 that acquires a control pulse signal and determines whether the pulse width of the control pulse signal exceeds the reference pulse width.

  In the first embodiment, when the pulse width of the control pulse signal exceeds the reference pulse width, the pulse width detector 3 outputs an error signal indicating the fact. As shown below, in the example of FIGS. 1 and 2, whether or not the pulse width of the control pulse signal exceeds the reference pulse width is determined by comparing the comparison signal with the reference signal.

  Specifically, in the example of FIGS. 1 and 2, the pulse width detection unit 3 includes a CR integration circuit 4 and a comparator 5. The CR integration circuit 4 is connected to the switching unit 13, and a control pulse signal is input to the CR integration circuit 4. As shown in FIG. 4, when the control pulse signal is input, the CR integration circuit 4 smoothes the control pulse signal and generates a comparison signal.

  The comparator 5 compares the voltage level of the comparison signal with the voltage level of a reference signal (not shown), and outputs an error signal if the voltage level of the comparison signal is higher than the voltage level of the reference signal. The reference signal is a preset voltage signal. The voltage level of the reference signal is appropriately set according to the specifications and characteristics of the DC motor 21 and the power source 22.

  In the first embodiment, the error signal is output to a control device (not shown) of the device in which the motor control device 1 is incorporated. When an error signal is output, the device control device displays that an excessive load is applied to the DC motor 21 on the display screen (not shown) of the device, or overturns the warning lamp. Sounds a warning buzzer. As a result, the operator of the device can immediately take an appropriate measure such as stopping the operation of the device, and the damage to the DC motor 21 can be minimized.

  As described above, according to the first embodiment, the abnormality of the DC motor 21 can be determined with a simple circuit configuration. Therefore, an increase in cost of the abnormality detection device 2 and the motor control device 1 can be suppressed. Further, as described above, the first embodiment can be applied to abnormality detection of a DC motor.

  By the way, as a method of detecting abnormality of the motor, a method using a vibration sensor is also conceivable. In this method, it is determined that an abnormality has occurred in the motor when the vibration sensor detects a certain amount of vibration. However, in this method, the motor may be determined to be abnormal even when vibration other than abnormal vibration of the device, for example, vibration by another device located in the vicinity of the device is detected. In contrast, in the first embodiment, it is determined that an abnormality has occurred in the motor only when the pulse width of the control pulse signal exceeds the reference pulse width. For this reason, according to this Embodiment 1, the reliability of abnormality determination can be improved compared with the method using a vibration sensor.

  Further, as a method for detecting motor abnormality, there is also known a method for determining that an abnormality has occurred in the motor when the rotational speed of the motor does not reach a set value within a set time. However, this method has a problem that an abnormality cannot be detected when a motor having a driving force larger than the design load value applied to the device is used. On the other hand, in the first embodiment, as described above, since abnormality is determined based on whether the pulse width of the control pulse signal exceeds the reference pulse width, the motor is driven regardless of the magnitude of the driving force of the motor. Can be detected.

  In the first embodiment, the configuration of the pulse width detection unit 3 is not limited to the example shown in FIG. For example, the pulse width detector 3 shown in FIG. 5 or 6 can be used. FIG. 5 is a block diagram illustrating another example of the abnormality detection device and the motor control device according to Embodiment 1 of the present invention. FIG. 6 is a block diagram illustrating another example of the abnormality detection device and the motor control device according to Embodiment 1 of the present invention.

  In the example of FIG. 5, the pulse width detector 6 is different from the pulse width detector 3 shown in FIG. 1, and includes a calculation means 7 instead of a comparator. In other respects, the motor control device shown in FIG. 5 is configured similarly to the motor control device shown in FIG.

  Although not shown, the calculation means 7 includes an A / D converter. The comparison signal generated by the integration circuit 4 is converted into a digital signal by the A / D converter. The computing means 7 compares the count number of the digital signal with the reference count number, and outputs an error signal when the count number of the digital signal is larger than the reference count number. The reference count number is set in advance. The reference count number is also appropriately set according to the specifications and characteristics of the DC motor 21 and the power source 22.

  In the example of FIG. 6, the pulse width detector 8 measures the time from the rising edge to the falling edge of the pulse of the control pulse signal. As a result of the measurement, the pulse width detection unit 8 outputs an error signal when the measured time is longer than the reference time. The reference time is also set in advance according to the specifications and characteristics of the DC motor 21 and the power source 22.

(Embodiment 2)
Next, the abnormality detection device and the motor control device according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 7 is a block diagram showing an abnormality detection device and a motor control device according to Embodiment 2 of the present invention. FIG. 8 is a circuit diagram showing an example of a specific circuit configuration of the motor control device shown in FIG.

  As shown in FIG. 7, in the second embodiment, the pulse width detector 9 detects the control pulse signal to the DC motor 21 when the pulse width of the control pulse signal exceeds a predetermined reference pulse width. Shut off the supply. Otherwise, the motor control device in the second embodiment is the same as the motor control device in the first embodiment.

  Here, an example of a specific circuit configuration of the motor control device shown in FIG. 7 will be described with reference to FIG. As shown in FIG. 8, the pulse width detection unit 9 includes a CR integration circuit 4 and a comparator 5 like the pulse width detection unit 3 shown in FIG. The comparator 5 outputs an error signal when the pulse width of the control pulse signal exceeds a predetermined reference pulse width, that is, when the voltage level of the comparison signal exceeds the voltage level of the reference signal.

  In the second embodiment, the pulse width detection unit 9 also includes a relay 10. The relay 10 constitutes a part of a power supply line that connects the power supply 22 and the switching unit 13. The coil constituting the relay 10 is connected to the comparator 5. For this reason, when an error signal is output, the relay 10 is opened and the power supply line is shut off. When a signal other than the error signal is output from the comparator 5, the relay 10 is closed and power is supplied to the switching unit 13 through the power supply line.

  Note that the means for interrupting the power supply line is not limited to the relay 10. Instead of the relay 10, a switching element such as a transistor may be used.

  As described above, according to the second embodiment, when an excessive load is applied to the DC motor 21, the DC motor 21 can be automatically stopped. Therefore, damage to the DC motor 21 can be minimized even if the operator of the device does not take appropriate measures as in the first embodiment. Also in the second embodiment, the effects described in the first embodiment can be obtained.

(Embodiment 3)
Next, an abnormality detection device and a motor control device according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing an abnormality detection device and a motor control device according to Embodiment 3 of the present invention.

  As shown in FIG. 9, also in the third embodiment, the rotational speed of the motor is controlled by the switching method. However, in the third embodiment, the motor to be controlled is an AC motor (AC motor) 23. Further, the motor control device 20 includes an inverter 11 composed of a plurality of switching elements instead of the switching unit shown in FIG. The AC motor 23 is driven by a control pulse signal generated by the inverter 11.

  In the third embodiment, the inverter 11 is a PWM inverter, and the starting unit 12 generates an input signal and inputs it to the inverter 11. The feedback unit 14 adjusts the duty ratio (pulse width) of the control pulse signal generated by the inverter 11 based on the control pulse signal output from the inverter 11 so that the rotational speed of the AC motor 23 is constant. is doing. In the third embodiment, the duty ratio is also adjusted by changing the voltage level of the input signal generated by the starting unit 12.

  The abnormality detection device 2 is the same as that shown in FIG. 1 in the first embodiment, and has a pulse width detection unit 3 including a CR integration circuit 4 and a comparator 5. In the third embodiment, when the pulse width of the pulse signal generated by the inverter 11 exceeds the reference pulse width, an error signal indicating that is output.

  As described above, also in the third embodiment, when an abnormality occurs in the AC motor 23, the operator of the device incorporating the motor control device 20 immediately takes appropriate measures such as stopping the operation of the device. And damage to the AC motor 23 can be minimized. Further, according to the third embodiment, it is possible to detect an abnormality with a simple configuration even for an AC motor. Furthermore, the effects described in the first embodiment can also be obtained in the third embodiment.

  As described above, according to the abnormality detection device and the motor control device of the present invention, it is possible to detect abnormality of a motor mounted on a home appliance, an automobile, a medical device, a measurement device, or the like. Therefore, in the device equipped with the abnormality detection device and the motor control device of the present invention, the reliability and durability of the device itself can be improved. The abnormality detection device and motor control device of the present invention have industrial applicability.

It is a block diagram which shows an example of the abnormality detection apparatus and motor control apparatus in Embodiment 1 of this invention. It is a circuit diagram which shows an example of the concrete circuit structure of the motor control apparatus shown in FIG. It is a figure which shows a mode that the pulse width of the pulse signal for control changes according to the load of a motor. It is a figure which shows the pulse signal for control input into the integration circuit which comprises a pulse width detection part, and the comparison signal output from the integration circuit. It is a block diagram which shows the other example of the abnormality detection apparatus and motor control apparatus in Embodiment 1 of this invention. It is a block diagram which shows the other example of the abnormality detection apparatus and motor control apparatus in Embodiment 1 of this invention. It is a block diagram which shows the abnormality detection apparatus and motor control apparatus in Embodiment 2 of this invention. It is a circuit diagram which shows an example of the concrete circuit structure of the motor control apparatus shown in FIG. It is a block diagram which shows the abnormality detection apparatus and motor control apparatus in Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 Motor control apparatus 2 Abnormality detection apparatus 3, 6, 8, 9 Pulse width detection part 4 CR integration circuit 5 Comparator 7 Calculation means 10 Relay 11 Inverter 12 Oscillation part 13 Switching part 14 Feedback part 15 Diode 16 Capacitor 21 DC motor 22 Power supply 23 AC motor

Claims (11)

An abnormality detection device for detecting an abnormality of a motor whose rotation speed is controlled by a switching method,
An abnormality detection comprising a pulse width detection unit that acquires a control pulse signal used for controlling the motor and determines whether a pulse width of the control pulse signal exceeds a reference pulse width apparatus. The pulse width detection unit has an integration circuit and a comparator,
The integration circuit generates a comparison signal by smoothing the control pulse signal,
The comparator compares the voltage level of the comparison signal with the voltage level of the reference signal, and when the voltage level of the comparison signal is greater than the voltage level of the reference signal, the pulse width of the control pulse signal is previously set. The abnormality detection apparatus according to claim 1, wherein an error signal indicating that the predetermined reference pulse width is exceeded is output. The pulse width detection unit includes an integration circuit, an A / D converter, and an arithmetic means.
The integration circuit generates a comparison signal by smoothing the control pulse signal,
The A / D converter converts the comparison signal into a digital signal;
The arithmetic means compares the count number of the digital signal with a reference count number, and when the count number of the digital signal is larger than the reference count number, the pulse width of the control pulse signal is predetermined. The abnormality detection device according to claim 1, wherein an error signal indicating that the reference pulse width is exceeded is output.   The pulse width detection unit measures the time from the rise to the fall of the pulse of the control pulse signal, and when the measured time is longer than a reference time, the pulse width of the control pulse signal is the reference The abnormality detection device according to claim 1, wherein an error signal indicating that the pulse width is exceeded is output.   The pulse width detection unit cuts off the supply of the control pulse signal to the motor when the pulse width of the control pulse signal exceeds the reference pulse width. The abnormality detection device described. A motor control device that controls the rotation speed of a motor by a switching method,
A switching unit that generates a control pulse signal used for controlling the motor by switching, and a pulse that acquires the control pulse signal and determines whether the pulse width of the control pulse signal exceeds a reference pulse width A motor control device comprising: a width detection unit.   The motor control device according to claim 6, further comprising a feedback unit that adjusts a switching time interval by the switching unit based on the control pulse signal. The pulse width detection unit has an integration circuit and a comparator,
The integration circuit generates a comparison signal by smoothing the control pulse signal,
The comparator compares the voltage level of the comparison signal with the voltage level of the reference signal, and when the voltage level of the comparison signal is greater than the voltage level of the reference signal, the pulse width of the control pulse signal is previously set. 8. The motor control device according to claim 6, wherein an error signal indicating that the predetermined reference pulse width is exceeded is output. The pulse width detection unit includes an integration circuit, an A / D converter, and an arithmetic means.
The integration circuit generates a comparison signal by smoothing the control pulse signal,
The A / D converter converts the comparison signal into a digital signal;
The arithmetic means compares the count number of the digital signal with a reference count number, and when the count number of the digital signal is larger than the reference count number, the pulse width of the control pulse signal is predetermined. The motor control device according to claim 6 or 7, wherein an error signal indicating that the reference pulse width is exceeded is output.   The pulse width detection unit measures the time from the rise to the fall of the pulse of the control pulse signal, and when the measured time is longer than a predetermined reference time, the pulse of the control pulse signal The motor control device according to claim 6 or 7, wherein an error signal indicating that a width exceeds a predetermined reference pulse width is output.   The pulse width detection unit cuts off the supply of the control pulse signal to the motor when the pulse width of the control pulse signal exceeds a predetermined reference pulse width. The motor control apparatus in any one.

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