JP2021061695A - Abnormality detection device for motor and vehicle with the same - Google Patents

Abstract

To detect abnormality of a motor generating power for vehicle in an actual use state.SOLUTION: An abnormality detection device 1 comprises: a movement sensor 10 which detects a moving speed of a vehicle; a current sensor 20 which detects a current flowing to a motor 5 to generate a current detection value M; an extraction circuit 30 which extracts a low-frequency component ML corresponding to the rotating speed of the motor 5 and a high-frequency component MH as a higher harmonic of the low-frequency component ML from the current detection value M; and a determination circuit 40 which analyzes the low-frequency component ML and high-frequency component MH when the movement sensor 10 indicates that variation in moving speed of the vehicle is within a predetermined range to determine abnormality of the motor 5. Thus, a determination on abnormality of the motor is made on condition that the variation in moving speed of the vehicle is within the predetermined range, so the abnormality detection can be performed in real time in a period in which variation in load condition is small during actual use.SELECTED DRAWING: Figure 1

Description

The present invention relates to an abnormality detection device for a motor, and more particularly to an abnormality detection device for a motor that is a power source for a vehicle.

As an abnormality detecting device for detecting an abnormality before the motor breaks down, the devices described in Patent Documents 1 and 2 are known. The device described in Patent Document 1 performs self-diagnosis by applying a step-like angle command to the motor and comparing the angular velocity at the time when the angular acceleration becomes zero with a preset maximum speed value. There is. Further, the apparatus described in Patent Document 2 analyzes the load current signal of the motor by spectrum analysis, and determines an abnormality based on the power frequency of the motor and the average order or dispersion order of the harmonic spectrum thereof.

Japanese Patent No. 3858350 Japanese Unexamined Patent Publication No. 11-083686

However, since the apparatus described in Patent Document 1 needs to be evaluated in a state where the load conditions are fixed, it is not possible to make a diagnosis in actual use when the load conditions change. Further, since the device described in Patent Document 2 converts the load current signal of the motor into a digital signal and performs spectral analysis based on the digital signal, the burden of hardware and software required for signal processing is burdened. There was a problem that it was big.

Moreover, the devices described in Patent Documents 1 and 2 are intended to be motors used for fixed devices such as radars and pumps. On the other hand, the motor, which is the power of a moving device such as a vehicle, has large fluctuations in load conditions and also causes changes in acceleration due to the movement of the vehicle. Therefore, it has been described in Patent Documents 1 and 2. It is difficult for the device to detect anomalies.

Therefore, an object of the present invention is to provide an abnormality detecting device capable of detecting an abnormality of a motor, which is a power of a vehicle, in actual use. Another object of the present invention is to provide a vehicle provided with such an abnormality detection device.

The abnormality detection device according to the present invention is a motor abnormality detection device that is the power of the vehicle, and is a movement sensor that detects the movement speed of the vehicle and a current that generates a current detection value by detecting the current flowing through the motor. The sensor, the extraction circuit that extracts the low-frequency component corresponding to the rotation speed of the motor and the high-frequency component that is the harmonic of the low-frequency component from the current detection value, and the change in the moving speed of the vehicle are within the predetermined range. When the mobile sensor indicates that, it is characterized by including a determination circuit for determining an abnormality of the motor by analyzing a low frequency component and a high frequency component. Further, the vehicle according to the present invention is provided with the above-mentioned abnormality detection device.

According to the present invention, since the abnormality determination of the motor is performed on the condition that the change in the moving speed of the vehicle is within a predetermined range, the abnormality is detected in real time during a period in which the change in the load condition is small during actual use. Can be done.

In the present invention, the determination circuit may make a determination when the movement sensor indicates that the moving speed of the vehicle is constant. According to this, it is possible to perform abnormality detection during a period in which the load condition does not change due to acceleration / deceleration of the vehicle. In this case, the determination circuit may make a determination when the movement sensor indicates that the moving direction of the vehicle is constant. According to this, it is possible to perform abnormality detection during a period in which the load condition does not change due to the turning of the vehicle.

In the present invention, the determination circuit may perform determination based on the difference or ratio between the low frequency component and the high frequency component. According to this, it is possible to detect an abnormality by a simple arithmetic process.

In the present invention, the extraction circuit is an analog circuit including a high-pass filter, and a high-frequency component may be extracted by inputting a current detection value to the high-pass filter. According to this, it is possible to reduce the load of digital processing.

In the present invention, the extraction circuit is an analog circuit including a low-pass filter and a subtractor, and a low-frequency component is extracted by inputting a current detection value to the low-pass filter, and a low-frequency component is extracted from the current detection value using a subtractor. It may be the one that extracts the high frequency component by reducing. In this case as well, the load of digital processing can be reduced.

In the present invention, the current sensor generates a current detection value by detecting a magnetic field generated by the current flowing through the motor, and the extraction circuit is an analog circuit including a low-pass filter and a compensation coil, and the current detection value is input to the low-pass filter. By doing so, the low frequency component is extracted, and the current corresponding to the low frequency component is passed through the compensation coil, thereby canceling the magnetic field component corresponding to the low frequency component contained in the magnetic field to extract the high frequency component. It doesn't matter if there is. In this case as well, the load of digital processing can be reduced.

As described above, according to the present invention, it is possible to detect an abnormality of the motor, which is the power of the vehicle, in real time during actual use.

FIG. 1 is a block diagram for explaining the configuration of a vehicle provided with the abnormality detection device 1 according to the first embodiment of the present invention. FIG. 2 is a schematic graph for explaining the relationship between the frequencies of the high frequency component MH and the low frequency component ML and the cutoff frequency of the filter. FIG. 3 is an example of a waveform diagram of the current detection value M. FIG. 4 is a waveform diagram showing an example of the difference (ML-MH) between the low frequency component ML and the high frequency component MH. FIG. 5 is a flowchart for explaining an example of the operation of the determination circuit 40. FIG. 6 is a block diagram for explaining the configuration of the vehicle provided with the abnormality detection device 2 according to the second embodiment of the present invention. FIG. 7 is a block diagram for explaining the configuration of a vehicle provided with the abnormality detection device 3 according to the third embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram for explaining the configuration of a vehicle provided with the abnormality detection device 1 according to the first embodiment of the present invention.

The vehicle shown in FIG. 1 has a wheel 4 for moving the vehicle body, a motor 5 for rotating the wheel 4, a three-phase AC power supply 6 for driving the motor 5, and an abnormality for detecting an abnormality before the motor 5 fails. It is provided with an abnormality detection device 1. The type of vehicle is not particularly limited, but it may be an automatic guided vehicle used in a factory or warehouse. Since the automatic guided vehicle is not operated by the operator, it is difficult to find a defect in the motor that is the power source. However, according to the present embodiment, it is possible to detect an abnormality in the motor during actual use. As a result, it is possible to prevent the motor from breaking down, and thus the maintainability is improved.

The abnormality detection device 1 includes a movement sensor 10, a current sensor 20, an extraction circuit 30, a determination circuit 40, a control unit 50, and an I / O device 60. The movement sensor 10 is a sensor capable of detecting at least the movement speed of the vehicle, and in the example shown in FIG. 1, it is composed of an acceleration sensor 11 and a low-pass filter 12. The acceleration sensor 11 is a sensor that detects the moving speed and turning direction of the vehicle by detecting the acceleration applied to the vehicle. The low-pass filter 12 is used to remove a noise component included in the output signal from the acceleration sensor 11. The output signal Ac of the mobile sensor 10 is supplied to the determination circuit 40.

However, it is not essential to use the acceleration sensor 11 for the movement sensor 10, and the movement speed of the vehicle may be detected by a method such as image recognition by a gyro sensor, radar, or camera shooting. However, as will be described later, since the abnormality detection device 1 according to the present embodiment has a configuration in which the abnormality determination is performed on the condition that the moving speed of the vehicle is constant or within a predetermined range, the movement sensor 10 is accelerated. It is most preferable to use the sensor 11.

The current sensor 20 generates a current detection value M by detecting the current flowing from the three-phase AC power supply 6 to the motor 5. The current sensor 20 used in the present embodiment includes a magnetic sensor that detects a magnetic field generated by a current flowing through the motor 5, but the present invention is not limited thereto. The type of element used in the magnetic sensor is not particularly limited, and a fluxgate element, a magnetic impedance element, a Hall element, an AMR element, a GMR element, a TMR element, or the like can be used. The current detection value M, which is an output signal of the current sensor 20, is supplied to the extraction circuit 30.

The extraction circuit 30 is an analog circuit including a low-pass filter 31, 35, 36, a high-pass filter 32, and buffers 33, 34. The low-pass filter 31 extracts the low-frequency component ML corresponding to the rotation speed of the motor 5 from the current detection value M, and the high-pass filter 32 extracts the high-frequency component MH which is a harmonic of the low-frequency component ML. The low frequency component ML is a component that matches the power supply frequency of the three-phase AC power supply 6, and is supplied to the determination circuit 40 via the buffer 33 and the low-pass filter 35. The cutoff frequencies f ₃₁ and f ₃₅ of the low-pass filters 31 and 35 are as shown in FIG. 2A, and another low-pass filter is used to remove the noise component MN contained in the output of the low-pass filter 31. 35 is inserted. However, it is not essential to provide such a low-pass filter 35 in the present invention. The buffer 33 is inserted to separate the front and rear filters.

On the other hand, the high frequency component MH is a harmonic of the low frequency component ML and is supplied to the determination circuit 40 via the buffer 34 and the low pass filter 36. _{The cutoff frequencies f 32} and f ₃₆ of the high-pass filter 32 and the low-pass filter 36 are as shown in FIG. 2 (b), respectively, and the cut-off frequencies are used to remove the noise component MN contained in the output of the high-pass filter 32. A high low-pass filter 36 is inserted. However, it is not essential to provide such a low-pass filter 36 in the present invention. The buffer 34 is inserted to separate the front and rear filters.

The determination circuit 40 is a circuit that receives the low frequency component ML and the high frequency component MH supplied from the extraction circuit 30 and digitally analyzes the low frequency component ML and the high frequency component MH to determine an abnormality of the motor 5. The determination by the determination circuit 40 can be performed based on the difference (ML-MH) or ratio (MH / ML) between the low frequency component ML and the high frequency component MH. Here, the determination circuit 40 does not constantly analyze the low-frequency component ML and the high-frequency component MH and determine the abnormality, but indicates that the change in the moving speed of the vehicle is within a predetermined range. Execute on the condition that Ac indicates. This is because when the moving speed of the vehicle changes significantly, that is, when the vehicle is accelerating or decelerating, the load condition of the motor 5 changes, so that the low frequency component ML and the high frequency component MH are used. This is because it is difficult to correctly determine the abnormality even if it is analyzed. On the other hand, when the change in the moving speed of the vehicle is within a predetermined range, the load condition of the motor 5 hardly changes. Therefore, by analyzing the low frequency component ML and the high frequency component MH, the abnormality can be correctly determined. It becomes possible to do.

The determination circuit 40 may analyze the low frequency component ML and the high frequency component MH and determine an abnormality on condition that the output signal Ac of the movement sensor 10 indicates that the moving speed of the vehicle is constant. Absent. When the moving speed of the vehicle is constant, the load condition of the motor 5 is substantially constant, so that it is possible to correctly determine the abnormality. In addition to this, the determination circuit 40 analyzes the low frequency component ML and the high frequency component MH and determines an abnormality on condition that the output signal Ac of the movement sensor 10 indicates that the moving direction of the vehicle is constant. You can go. When the moving speed and moving direction of the vehicle are constant, that is, when the vehicle is moving linearly at a constant speed, the load condition of the motor 5 is almost completely constant, so that the abnormality can be determined more. It will be possible to do it correctly.

FIG. 3 is an example of a waveform diagram of the current detection value M, where reference numeral A indicates a waveform when an abnormality has not occurred in the motor 5, and reference numeral B indicates a waveform when an abnormality has occurred in the motor 5. There is. As shown in FIG. 3, even if the moving conditions of the vehicle are the same, there is a difference in the current detection value M between the case where the motor 5 has no abnormality (A) and the case where the abnormality has occurred (B). ..

FIG. 4 is a waveform diagram showing an example of the difference (ML-MH) between the low frequency component ML and the high frequency component MH. Shows the difference when an abnormality occurs in. As shown in FIG. 4, it can be seen that when the motor 5 has an abnormality (B), the peak of the ML-MH value becomes larger than when the motor 5 has no abnormality (A). .. Therefore, the determination circuit 40 can determine the abnormality of the motor 5 based on the peak of the value of ML-MH.

Then, when the determination circuit 40 determines the abnormality of the motor 5, the determination circuit 40 notifies the control unit 50 of this. The control unit 50 is a device that controls the operation of the entire vehicle, and when an abnormality of the motor 5 is detected by the determination circuit 40, an abnormality is sent to the operator via an I / O device 60 including a lamp, a buzzer, and the like. Notify. This allows the operator to recognize the occurrence of an abnormality before the motor 5 actually fails.

FIG. 5 is a flowchart for explaining an example of the operation of the determination circuit 40.

In the operation of the determination circuit 40, the operator first sets the upper limit value AcUL of the acceleration, the lower limit value AcLL of the acceleration, and the failure determination value FL (step S1). When the setting of various values is completed, it waits (step S2) and acquires the current acceleration Ac (step S3). This means that the output signal Ac from the movement sensor 10 including the acceleration sensor 11 is taken in. Then, the acquisition of the current detection value M is started on condition that the acquired acceleration Ac is less than the upper limit value AcUL (step S4) and exceeds the lower limit value AcLL (step S5) (step S6). That is, the acquisition of the current detection value M is started on condition that the change in the moving speed of the vehicle is within a predetermined range. Here, if the difference between the upper limit value AcUL and the lower limit value AcLL is set small, a more accurate determination operation can be performed. On the other hand, if the acquired acceleration Ac is equal to or higher than the upper limit value AcUL or equal to or lower than the lower limit value AcLL, the process returns to step S2 and waits. That is, when the change in the moving speed of the vehicle exceeds a predetermined range, the current detection value M is not acquired.

In the acquisition operation of the current detection value M, the count value N is first reset to 0 (step S7), the acquired high frequency component MH is integrated to calculate the high frequency integrated value MHt (step S8), and the acquired low frequency is acquired. The low frequency integrated value MLt is calculated by integrating the component ML (step S9). Next, the count value N is incremented (step S10), and the process returns to step S8 (step S11). This operation is repeated until the count value N exceeds a predetermined value (for example, 16), and when the count value N exceeds the predetermined value, the value of MHt / MLt is calculated (step S12). Then, when the value of MHt / MLt exceeds the failure determination value FL, an abnormal signal is output and the process ends (step S13). On the other hand, when the value of MHt / MLt is equal to or less than the failure determination value FL, the process returns to step S2 and waits.

As described above, the abnormality detection device 1 according to the present embodiment acquires the current detection value M on the condition that the change in the moving speed of the vehicle is within a predetermined range, and analyzes the high frequency component MH and the low frequency component ML. By doing so, it is determined whether or not there is an abnormality in the motor 5. Therefore, it is possible to determine the presence or absence of an abnormality in real time during actual use without being affected by the load fluctuation of the motor 5. Moreover, since the extraction circuit 30 is an analog circuit including a high-pass filter and a low-pass filter, the load of digital processing can be minimized.

Further, as shown in the flowchart shown in FIG. 5, if the high frequency component MH and the low frequency component ML are integrated to calculate the high frequency integrated value MHt and the low frequency integrated value MLt, and the presence or absence of an abnormality is determined based on these, an error is made. It is possible to reduce the number of judgments.

FIG. 6 is a block diagram for explaining the configuration of the vehicle provided with the abnormality detection device 2 according to the second embodiment of the present invention.

As shown in FIG. 6, the abnormality detection device 2 according to the second embodiment of the present invention differs from the abnormality detection device 1 according to the first embodiment in that the extraction circuit 30 is replaced with the extraction circuit 30A. ing. Since the other basic configurations are the same as those of the abnormality detection device 1 according to the first embodiment, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

The extraction circuit 30A omits the high-pass filter 32 included in the extraction circuit 30, and instead includes an amplifier 37 and a subtractor 38. The amplifier 37 receives the low frequency component ML output from the low-pass filter 31 and feeds it back to the subtractor 38. The subtractor 38 extracts the high frequency component MH by subtracting the low frequency component ML from the current detection value M output from the current sensor 20. The extracted high-frequency component MH is supplied to the determination circuit 40 via the buffer 34 and the low-pass filter 36.

As illustrated by the present embodiment, in the present invention, it is not essential to extract the high frequency component MH using a high-pass filter, and the high frequency component MH may be extracted using a feedback circuit that cancels the low frequency component ML. Absent.

FIG. 7 is a block diagram for explaining the configuration of a vehicle provided with the abnormality detection device 3 according to the third embodiment of the present invention.

As shown in FIG. 7, the abnormality detection device 3 according to the third embodiment of the present invention differs from the abnormality detection device 2 according to the second embodiment in that the extraction circuit 30A is replaced with the extraction circuit 30B. ing. Since the other basic configurations are the same as those of the abnormality detection device 2 according to the second embodiment, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

The extraction circuit 30B omits the subtractor 38 included in the extraction circuit 30A and includes a compensation coil 39 instead. A compensation current output from the amplifier 37, that is, a current corresponding to the low frequency component ML flows through the compensation coil 39. As a result, of the magnetic field generated by the current flowing through the motor 5, the component corresponding to the low frequency component ML is canceled, so that the high frequency component MH is extracted. The extracted high-frequency component MH is supplied to the determination circuit 40 via the buffer 34 and the low-pass filter 36.

As illustrated by the present embodiment, in the present invention, it is not essential to extract the high frequency component MH by analog processing with respect to the current detection value M, and by using the compensation coil 39, the magnetic field component corresponding to the low frequency component ML can be obtained. The high frequency component MH may be extracted by canceling.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and these are also the present invention. Needless to say, it is included in the range.

1-3 Abnormality detection device 4 Wheel 5 Motor 6 Three-phase AC power supply 10 Mobile sensor 11 Acceleration sensor 12 Low-pass filter 20 Current sensor 30, 30A, 30B Extraction circuit 31, 35, 36 Low-pass filter 32 High-pass filter 33, 34 Buffer 37 Amplifier 38 Subtractor 39 Compensation coil 40 Judgment circuit 50 Control unit M Current detection value MH High frequency component ML Low frequency component MN Noise component

Claims (8)

It is an abnormality detection device for the motor that powers the vehicle.
A movement sensor that detects the moving speed of the vehicle and
A current sensor that generates a current detection value by detecting the current flowing through the motor, and
An extraction circuit that extracts a low-frequency component corresponding to the rotation speed of the motor and a high-frequency component that is a harmonic of the low-frequency component from the current detection value.
When the movement sensor indicates that the change in the moving speed of the vehicle is within a predetermined range, a determination circuit for determining an abnormality of the motor by analyzing the low frequency component and the high frequency component, and a determination circuit. An abnormality detection device for a motor, which comprises. The motor abnormality detection device according to claim 1, wherein the determination circuit makes the determination when the movement sensor indicates that the moving speed of the vehicle is constant. The motor abnormality detection device according to claim 2, wherein the determination circuit makes the determination when the movement sensor indicates that the moving direction of the vehicle is constant. The motor abnormality detection device according to any one of claims 1 to 3, wherein the determination circuit makes the determination based on the difference or ratio between the low frequency component and the high frequency component. The extraction circuit is an analog circuit including a high-pass filter, and according to any one of claims 1 to 4, the high-frequency component is extracted by inputting the current detection value to the high-pass filter. Motor abnormality detector. The extraction circuit is an analog circuit including a low-pass filter and a subtractor, and the low-frequency component is extracted by inputting the current detection value to the low-pass filter, and the subtractor is used to extract the low-frequency component, and the current detection value is used to extract the low-frequency component. The motor abnormality detection device according to any one of claims 1 to 4, wherein the high frequency component is extracted by reducing the low frequency component. The current sensor generates a current detection value by detecting a magnetic field generated by a current flowing through the motor.
The extraction circuit is an analog circuit including a low-pass filter and a compensation coil, and the low-frequency component is extracted by inputting the current detection value to the low-pass filter, and the current corresponding to the low-frequency component is applied to the compensation coil. The motor according to any one of claims 1 to 4, wherein the high-frequency component is extracted by canceling the magnetic field component corresponding to the low-frequency component contained in the magnetic field. Abnormality detection device. A vehicle provided with the abnormality detection device according to any one of claims 1 to 7.

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