JP4631427B2 - Fault detector for rotational speed detector - Google Patents

Description

  The present invention relates to a failure detection device for a rotational speed detector that detects the rotational direction and rotational speed of a rotating body such as a motor.

  FIG. 8 is a block diagram showing a schematic configuration of a conventional rotational speed detector 10. The rotational speed detector 10 has a two-phase phase shifted by 90 degrees in synchronization with the rotation of a rotating body (not shown). An encoder 1 that outputs a pulse signal, and a direction discriminating circuit that determines the rotation direction of the rotating body based on the two-phase pulse signal and outputs the up signal 70 or the down signal 80 synchronized with the rotation based on the determination result 2 and an up / down counter 3 that counts the up signal 70 or the down signal 80, and the rotation direction and rotation of the rotating body based on the increase / decrease direction of the count value of the up / down counter 3 and the amount of change per unit time. The speed is detected (see Patent Document 1).

In order to detect an abnormality of the rotational speed detector 10, a disconnection detection device 90 is provided. The disconnection detection device 90 includes a disconnection determination unit 91 to which a count value is supplied from the up / down counter 3, a disconnection detection counter 92 that counts up the count value according to an instruction from the disconnection determination unit 91, and a count value of the up / down counter 3 The disconnection determination unit 91 compares the count value of the up / down counter 3 with the counter stored value stored in the count value storage unit 93, and determines both values. When the absolute value of the difference between the two is less than 2, the count value of the disconnection detection counter 92 is counted up, and when the count value is equal to or greater than a preset value, it is determined that a disconnection has occurred. .
Japanese Patent Laid-Open No. 2001-249154 Japanese Examined Patent Publication No. 4-26067

  However, in the conventional disconnection detecting device 90, the presence or absence of disconnection by the up signal 70 or the down signal 80 output based on the state of the other signal when one of the A phase signal 50 or the B phase signal 60 changes. Is judged. Therefore, although it can be used for disconnection detection of the speed detector of the rotating body at both-phase edges using the A-phase signal 50 and the B-phase signal 60, the speed detecting device of the rotating body at one-phase one-edge. There is a problem that it cannot be applied to the detection of disconnection.

The disconnection determination unit 91 determines that a disconnection has occurred when the absolute value of the difference between the count value of the up / down counter 3 and the counter stored value stored in the count value storage unit 93 is less than 2. . Therefore, even when the rotating body is rotating at a low speed and the up signal 70 or the down signal 80 is counted only once in a certain period, the rotating body is erroneously determined to be disconnected and can detect the disconnection. There is a problem that the speed range is limited.
The present invention has been made to solve the above-described problems of the prior art, and the object thereof can be applied to a speed detector using an A-phase signal and a B-phase signal regardless of the detection method thereof. An object of the present invention is to provide a disconnection detecting device capable of detecting disconnection in a wide range of speeds of a rotating body.

  According to a first aspect of the present invention, there is provided a failure determination device for a rotational speed detector according to a first frequency signal proportional to a rotational frequency of a rotating body, and the first frequency signal having the same frequency as the first frequency signal. In a failure detection device for a rotational speed detector that detects the rotational direction and rotational speed of the rotating body based on a second frequency signal having a predetermined phase difference with respect to the frequency signal of the first frequency signal, A first counter that counts in synchronization, resets or decrements the count value in synchronization with the second frequency signal, and counts in synchronization with the second frequency signal; A second counter that resets or decrements in synchronization with the first frequency signal, and when one of the count values exceeds a predetermined value, the rotation speed detector is turned off. It characterized by having a a determining means for determining a.

  According to a second aspect of the present invention, there is provided a failure determination device for a rotational speed detector according to a first frequency signal proportional to a rotational frequency of a rotating body, and the same frequency as the first frequency signal. In a failure detection apparatus for a rotational speed detector that detects a rotational direction and a rotational speed of the rotating body based on a second frequency signal having a predetermined phase difference with respect to the first frequency signal, the first frequency A first counter that counts in synchronization with the signal, resets or decrements the first count value in synchronization with the second frequency signal, and counts in synchronization with the second frequency signal; A second counter that resets or decrements the second count value in synchronization with the first frequency signal; and counts in synchronization with a third frequency signal having a fixed period; A third counter for resetting or decrementing the count value in synchronization with the first frequency signal and resetting or decrementing in synchronization with the second frequency signal; and the first count value or the second count value Determining means for determining that the rotational speed detector is faulty when one of the two exceeds a predetermined value, or when the third count value exceeds a predetermined value. To do.

According to a third aspect of the present invention, there is provided the failure detector for a rotational speed detector according to the first aspect, wherein the first frequency signal and the second frequency signal are pulses. And the first counter and the second counter perform the counting and the resetting or decrementing at an edge portion of the pulse signal.
According to a fourth aspect of the present invention, there is provided a malfunction detector for a rotational speed detector according to the second aspect, wherein the first frequency signal, the second frequency signal, and the second frequency signal are the same. The frequency signal of 3 is a pulse signal, and the first counter, the second counter, and the third counter perform the count and the reset or decrement at an edge portion of the pulse signal. .

According to the present invention, the speed detector of the rotating body using the A-phase signal and the B-phase signal can be determined by using the first frequency signal and the second frequency signal directly to determine the failure of the rotational speed detector. In the disconnection detection in, it can be applied regardless of the speed detection method.
In particular, according to the inventions according to claims 2 and 4, even when the rotating body rotates at a low speed by the configuration in which the failure of the rotation speed detector is determined using the third frequency signal having a constant period. A failure can be determined appropriately, and the speed range of the rotating body capable of determining the failure can be expanded.

A first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a failure detector for a rotational speed detector according to a first embodiment of the present invention provided in the rotational speed detector. The rotational speed detector 10 is a rotating body ( Encoder 1 that outputs a two-phase pulse signal that is out of phase in synchronization with the rotation (not shown), and determines the rotation direction of the rotating body based on the two-phase pulse signal and rotates based on the determination result And a direction discriminating circuit 2 that outputs an up signal 70 or a down signal 80 synchronized with the above, and an up / down counter 3 that counts the up signal 70 or the down signal 80, and the increase / decrease direction of the count value of the up / down counter 3 and The rotational direction and rotational speed of the rotating body are detected based on the amount of change per unit time.

  In this case, the encoder 1 outputs the A-phase signal 50 and the B-phase signal 60 that are 90 degrees out of phase as two-phase pulse signals, and when the rotating body is rotating forward, the B-phase signal When the phase of 60 is 90 degrees behind the phase A signal 50 and is rotating in reverse, the phase A is set so that the phase A signal 50 is 90 degrees behind the phase B signal 60. The signal 50 and the B phase signal 60 are output.

As shown in FIG. 1, the failure detection device 4 includes a counter 41, a counter 42, and a disconnection determination unit 43.
The counter 41 generates both rising and falling edge portions of the A-phase signal 50 as the count signal 11 and counts this to count up the count value 13 and both rising and falling edge portions of the B-phase signal 60. Is generated as the reset signal 12, and the count value 13 is reset (zero cleared).

The counter 42 generates both rising and falling edge portions of the B-phase signal 60 as the count signal 21 and counts this to count up the count value 23 and both rising and falling edge portions of the A-phase signal 50. Is generated as the reset signal 22 and the count value 23 is reset.
The disconnection determination unit 43 receives the count value 13 and the count value 23 from the counter 41 and the counter 42, and the count value 13 or the count value 23 is equal to or greater than a predetermined threshold (predetermined value). And disconnection detection signal (not shown) is output.

  Here, the threshold value for disconnection determination can be arbitrarily determined, so that the rotating body rotates at a low speed and the count signals 11 and 21 are counted only once in a certain period, or In the case of pulse cracking of the A-phase signal 50 or the B-phase signal 60, it can be easily avoided that the wire is determined to be disconnected.

  FIG. 2 is a timing chart showing the state of each signal when both signal lines of the A-phase signal and the B-phase signal are not disconnected, and when the A-phase signal 50 and the B-phase signal 60 are not disconnected. Since the phases of the A-phase signal 50 and the B-phase signal 60 are shifted by 90 degrees, the edge portions of the A-phase signal 50 and the B-phase signal 60 appear alternately. Therefore, the counter 41 and the counter 42 generate the count signal 11 or the count signal 21 and the reset signal 12 or the reset signal 22 alternately. As a result, the count value 13 and the count value 23 of the counter 41 and the counter 42 are alternately counted up to the count value 1 and reset to the count value 0, and the count value takes 0 or 1.

  FIG. 3 is a timing chart showing the state of each signal when the signal line of the B-phase signal is disconnected. When the B-phase signal 60 is disconnected, the edge portion starts from the B-phase signal 60. Therefore, the count signal 21 and the reset signal 12 are not generated. Therefore, since the counter 42 does not generate the count signal 21 but generates the reset signal 22 at each edge portion of the A-phase signal 50, the count value 23 continues to take 0 in the reset state. Since the counter 41 generates the count signal 11 but does not generate the reset signal 12 at each edge portion of the B-phase signal 60, the count value 13 continues to be counted up without being reset.

FIG. 4 is a timing chart showing the state of each signal when the signal line for the A phase signal is disconnected. Even when the A phase signal 50 is disconnected, the count signal 11 and the reset signal 22 are Since it is not generated, the count value 13 of the counter 41 continues to take 0, while the count value 23 of the counter 42 continues to be counted up.
The disconnection determination unit 43 that has received the count value 13 and the count value 23 of the counter 41 and the counter 42 has a value of the count value 13 or the count value 23 equal to or greater than a predetermined value (2 in the present embodiment). Is determined that the B-phase signal 60 or the A-phase signal 50 is disconnected, and outputs a disconnection detection signal.

As described above, since the failure detection device 4 determines the disconnection by directly using the output signals (A phase signal 50 and B phase signal 60) of the encoder 1, both phases of the A phase signal 50 and the B phase signal 60 are determined. The present invention is not limited to speed detectors at both edges, and can be applied regardless of the speed detection method.
Further, pulse signals are used as the A-phase signal 50 and the B-phase signal 60, and the counter 41 and the counter 42 perform simple counting and resetting or decrementing at both edges of the pulse signal, thereby making it easy to use a known circuit. Detailed failure detection is also possible with a simple configuration.

Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a block diagram showing a schematic configuration of a failure detection device for a rotation speed detector according to the second embodiment of the present invention provided in the rotation speed detector. The failure detection device 5 includes a counter 41, A counter 42, a disconnection determination unit 43, an OR circuit 56, a counter 54, and a disconnection determination unit 55 are provided.

In addition, the same code | symbol is attached | subjected to the structure similar to what was demonstrated using FIG. 1 in 1st Embodiment, and the description is abbreviate | omitted.
The OR circuit 56 receives the A-phase signal 50 and the B-phase signal 60 from the encoder 1, and both the rising and falling edge portions of the A-phase signal 50 and the rising and falling edge portions of the B-phase signal 60 are all. At the edge portion, a reset signal 61 is generated and output to the counter 54.

  The counter 54 receives a pulse signal 57 having a constant period, which is sufficiently higher in frequency than the A-phase signal 50 and the B-phase signal 60, such as a clock signal, and counts both rising and falling edge portions of the pulse signal 57. This is generated as a signal 62 and counted to count up the count value 63, and the count value 63 is reset by a reset signal 61 input from the OR circuit 56.

The disconnection determination unit 55 receives the count value 63 of the counter 54, determines that it is disconnected when the count value 63 is equal to or greater than a predetermined threshold value (predetermined value), and detects a disconnection detection signal ( (Not shown) is output.
In the present embodiment, as the threshold value for disconnection determination, the maximum value counted by the counter 54 when one phase of the A phase signal 50 or the B phase signal 60 is normal is based on the speed command to the rotating body. A value slightly larger than the value is set.

  FIG. 6 is a timing chart showing a state of each signal when both signal lines of the A phase signal and the B phase signal are not disconnected. When the A phase signal 50 and the B phase signal 60 are not disconnected, FIG. The counter 54 receives the reset signal 61 at regular intervals. As a result, the count value 63 of the counter 54 repeatedly takes a numerical value within a certain range (such as 0, 1, 2, 0, 1, 2,...).

  FIG. 7 is a timing chart showing the state of each signal when the signal line for the A phase signal and the signal line for the B phase signal are disconnected, and the A phase signal 50 and the B phase signal 60 are disconnected. In this case, since the edge portion cannot be detected from the A-phase signal 50 and the B-phase signal 60, the reset signal 61 is not output from the OR circuit 56. Therefore, the counter 54 does not receive the reset signal 61, but generates the count signal 62 at the edge portion of the pulse signal 57, so the count value 63 continues to be counted up without being reset.

  The disconnection determination unit 55 that receives the count value 63 of the counter 54 is a value that the counter 54 counts when the count value 63 of the counter 54 is normal in one of the A-phase signal 50 and the B-phase signal 60. When the value is a little larger than the maximum value, it is determined that both phases of the A-phase signal 50 and the B-phase signal 60 are disconnected, and a disconnection detection signal (not shown) is output.

As described above, the disconnection detection can be performed not only when one phase of the A phase signal 50 or the B phase signal 60 is disconnected but also when both phases of the A phase signal 50 and the B phase signal 60 are disconnected.
Moreover, since the threshold value for the disconnection determination of the disconnection determination unit 55 can be set based on the speed command or the estimated speed value to the rotating body, for example, the rotating body is rotating at a low speed and is in a certain period. In the case where the count signal 62 is counted only once, or in the case of pulse cracking of the A-phase signal 50 or the B-phase signal 60, it can be easily avoided that it is determined that the wire is broken. It is also possible to easily detect a disconnection in an appropriate detection time corresponding to the rotation speed.

Further, the pulse signal 57 is used as the A-phase signal 50 and the B-phase signal 60, and the counter 41, the counter 42, and the counter 54 are known by performing counting and resetting at all edge portions of the pulse signal. Detailed failure detection is possible with a simple configuration using a circuit.
As mentioned above, although embodiment of this invention was described, this invention is not limited to this, A various change and improvement can be performed.

For example, the rotational speed detector failure detection apparatus according to the present invention is applied to a speed detector at both edges of the A-phase signal 50 and the B-phase signal 60 in this embodiment. It can also be applied to velocity detectors at one-phase one-edge.
In this embodiment, pulse signals are used as the A-phase signal 50, the B-phase signal 60, and the pulse signal 57. However, the present invention is not limited to this, and a frequency signal such as a sine wave signal may be used. Good.

In the present embodiment, the count signals 11 and 21 and the reset signals 12 and 22 are generated at both rising and falling edges of the A-phase signal 50 and the B-phase signal 60. If it is synchronized with the B-phase signal 60, it can be generated at an arbitrary timing.
The counter 41 and the counter 42 alternately generate the count signals 11 and 21 or the reset signals 12 and 22, and the count value 13 and the count value 23 are alternately counted up to the count value 1 and reset to the count value 0. If the count signals 11 and 21 or the reset signals 12 and 22 are synchronized with the A-phase signal 50 or the B-phase signal 60, the count values 13 and 23 are set by the count signals 11 and 21, respectively. It is also possible to reset to 0 by reset signals 12 and 22 after counting up to a numerical value within a certain range.

  Similarly, in the present embodiment, the count signal 62 is generated at each edge portion of the pulse signal 57 and both the rising and falling edge portions of the A phase signal 50 and both the rising and falling edge portions of the B phase signal 60 are generated. The reset signal 61 is generated at all the edge portions of the signal. However, if the count signal 62 or the reset signal 61 is synchronized with the pulse signal 57, the A-phase signal 50, or the B-phase signal 60, any timing is possible. Can be generated. Further, the counter 54 receives the reset signal 61 at regular intervals, and the count value 63 of the counter 54 repeatedly takes a numerical value within a certain range, but the counter 54 generates the count signal 62. Alternatively, the reset signal 61 may be alternately received, and the count value 63 may be alternately incremented to the count value 1 and reset to the count value 0.

  Further, in the present embodiment, the counters 41 and 42 generate the reset signals 12 and 22, and the counter 54 receives the reset signal 61, the count values 13, 23 and 63 are reset to 0. Each time the reset signal 12, 22 or 61 is generated or received, the count values 13, 23 and 63 can be decremented (count down by 1).

  In the present embodiment, circuits for generating the count signals 11 and 21 and reset signals 12 and 22 are incorporated in the counters 41 and 42, and a circuit for generating the count signal 62 is incorporated in the counter 54. However, the circuit for generating the count signals 11, 21, 62 and the circuit for generating the reset signals 12, 22 may be provided independently. In the present embodiment, these circuits are configured as analog circuits. However, they can be configured as digital processing by being configured as software and processed by a microcomputer or the like.

It is a block diagram which shows schematic structure of the failure detection apparatus of the rotational speed detector which concerns on the 1st Embodiment of this invention with which the rotational speed detector was equipped. It is a timing chart figure which shows the state of each signal when both signal lines of A phase signal and B phase signal are not disconnected. It is a timing chart figure which shows the state of each signal when the signal line of a B-phase signal is disconnected. It is a timing chart figure which shows the state of each signal when the signal line of A phase signal is disconnected. It is a block diagram which shows schematic structure of the failure detection apparatus of the rotational speed detector which concerns on the 2nd Embodiment of this invention with which the rotational speed detector was equipped. It is a timing chart figure which shows the state of each signal when both signal lines of A phase signal and B phase signal are not disconnected. It is a timing chart figure which shows the state of each signal when the signal line of A phase signal and the signal line of B phase signal are disconnected. It is a block diagram which shows schematic structure of the disconnection detection apparatus with which the rotational speed detector by the encoder described in patent document 1 was equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Encoder 2 Direction discrimination circuit 3 Up / down counter 4 Failure detection device 5 Failure detection device 10 Rotation speed detector 11 Count signal 12 Reset signal 13 Count value 21 Count signal 22 Reset signal 23 Count value 41 Counter 42 Counter 43 Disconnection determination part 50 A phase signal 54 Counter 55 Disconnection determination unit 56 OR circuit 57 Pulse signal 60 B phase signal 61 Reset signal 62 Count signal 63 Count value 70 Up signal 80 Down signal 90 Conventional disconnection detection device 91 Disconnection determination unit 92 Disconnection detection counter 93 Count Value storage

Claims (4)

A first frequency signal proportional to the rotational frequency of the rotating body, and a second frequency signal having the same frequency as the first frequency signal and having a predetermined phase difference with respect to the first frequency signal. In a failure detection device for a rotational speed detector that detects the rotational direction and rotational speed of the rotating body based on
A first counter that counts in synchronization with the first frequency signal and resets or decrements the count value in synchronization with the second frequency signal;
A second counter that counts in synchronization with the second frequency signal and resets or decrements the count value in synchronization with the first frequency signal;
A determination means for determining that the rotational speed detector is faulty when either one of the count values exceeds a predetermined value;
A failure detection device for a rotational speed detector. A first frequency signal proportional to the rotational frequency of the rotating body, and a second frequency signal having the same frequency as the first frequency signal and having a predetermined phase difference with respect to the first frequency signal. In a failure detection device for a rotational speed detector that detects the rotational direction and rotational speed of the rotating body based on
A first counter that counts in synchronization with the first frequency signal and resets or decrements the first count value in synchronization with the second frequency signal;
A second counter that counts in synchronization with the second frequency signal and resets or decrements the second count value in synchronization with the first frequency signal;
Counting in synchronization with a third frequency signal having a fixed period, resetting or decrementing the third count value in synchronization with the first frequency signal, and resetting or decrementing in synchronization with the second frequency signal A third counter to
When either one of the first count value or the second count value exceeds a predetermined value, or when the third count value exceeds a predetermined value, the rotational speed detector is regarded as a failure. Determination means for determining;
A failure detection device for a rotational speed detector.   The first frequency signal and the second frequency signal are pulse signals, and the first counter and the second counter perform the count and the reset or decrement at an edge portion of the pulse signal. The failure detection device for a rotation speed detector according to claim 1, wherein   The first frequency signal, the second frequency signal, and the third frequency signal are pulse signals, and the first counter, the second counter, and the third counter are configured to count and reset or decrement, The failure detection apparatus for a rotation speed detector according to claim 2, wherein the failure detection apparatus performs the detection at an edge portion of the pulse signal.

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