JP2018182962A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the possible occurrence of an abnormality in the conventional non-isolated motor control device, in which external control equipment is connected through a common ground line, due to the flow of a motor drive current into the common ground line when a line break occurs on a power ground line.SOLUTION: A motor control device 1, having external control equipment 51 connected through a common ground line 5, is configured to include: a motor drive circuit 2 which supplies a drive current A to a motor M; a motor control circuit 3 which outputs a control signal to the motor drive circuit 2; an inner ground line 4 of the motor drive circuit 2 and the motor control circuit 3; a common ground line 5 which connects the external control equipment 51 to the inner ground line 4; and a protection circuit 6 which detects a current flowing through the common ground line 5 to output a motor stop signal to the motor control circuit 3. If a line break or the like occurs on a power ground line L2, the occurrence of abnormal motor operation and line burning caused thereby is prevented in advance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-insulated motor control apparatus to which an external control device is connected via a common ground line, and more particularly to a motor control apparatus provided with a protection circuit against an abnormal current caused by disconnection or the like.

  Conventionally, as a control device provided with a protection circuit, for example, there is one described in Patent Document 1 under the name of an electronic control system. The electronic control system described in Patent Document 1 includes a plurality of electronic control devices mounted on a vehicle, and mutually connects the electronic control devices via a shield line in which a signal line is covered by a shield member. This electronic control system is provided with protection means for preventing an overcurrent from flowing in the shield member of the shield wire when a disconnection or the like occurs between the ground terminal of each electronic control device and the negative terminal of the battery. Configuration.

Patent No. 5304620

  By the way, in a motor control device to which an external control device is connected via a common ground line, when a break or the like occurs in the power supply ground line, the drive current of the motor flows as an abnormal current to the external control device, causing damage to the ground line Abnormal operation of the motor may occur. Such abnormal operation of the motor is a situation that does not occur in the above-described electronic control system.

  Therefore, as a general protection means in the motor control device, means such as a fuse, a PTC thermistor and a resistor can be mentioned. However, in the case of using a fuse, replacement of parts is indispensable, and in the case of using other means, a voltage drop on the ground line causes an offset voltage in the indicated value of the motor, which causes an abnormal operation of the motor. Conventionally, there has been a problem in solving such problems because of the fear.

  The present invention has been made in view of the above-described conventional situation, and is a motor control device to which an external control device is connected via a common ground line, and in the case where a disconnection or the like occurs in a power supply ground line. An object of the present invention is to provide a motor control device capable of preventing occurrence of an abnormality caused by this.

  The motor control device according to the present invention is a motor control device to which an external control device is connected via a common ground line, and outputs a control signal to a motor drive circuit that supplies drive current to the motor and the motor drive circuit. And an internal ground line of the motor drive circuit and the motor control circuit. The motor control device further includes a common ground line connecting the external control device and the internal ground line, and a protection circuit detecting a current flowing in the common ground line and outputting a motor stop signal to the motor control circuit. It is set as a means, and it is set as a means for solving a subject with the said structure.

  In the motor control device according to the present invention, when the external control device is connected, the common ground line and the internal ground line function as a common ground line with the external control device. In such a motor control device, for example, when a break or the like occurs in the power supply ground line, a control circuit current flowing in the motor control circuit flows in the direction of the commonization ground line as an abnormal current. At this time, the motor control device detects the control circuit current (abnormal current) by the protection circuit provided on the common ground line, outputs a motor stop signal to the motor control circuit, and stops the motor via the motor drive circuit. Let Thus, an offset voltage does not occur in the command value of the motor due to the voltage drop of the ground line, and the drive current of the motor is prevented from flowing to the external control device side.

  In this manner, the motor control device according to the present invention is caused when a break or the like occurs in the power supply ground line in the motor control device to which the external control device is connected via the common ground line. Abnormality can be prevented in advance.

FIG. 1 is a circuit diagram for explaining a first embodiment of a motor control device according to the present invention. FIG. 5 is a circuit diagram showing a state in which a power supply ground line is disconnected in the motor control device shown in FIG. 1; FIG. 6 is a circuit diagram for explaining a second embodiment of the motor device according to the present invention. FIG. 4 is a circuit diagram showing a state in which a power supply ground line is disconnected in the motor control device shown in FIG. 3;

First Embodiment
1 and 2 are diagrams for explaining a first embodiment of a motor control device according to the present invention. In each of the drawings described below, a line through which the drive current A of the motor M flows is indicated by a thick solid line, and a line through which minute control circuit currents (substantially signals) B and C flow is indicated by a thin solid line. The drive current A of the motor M is a current value which is clearly larger than the control circuit currents B and C. Therefore, in this type of motor control device, the respective configurations are connected using lines corresponding to the magnitudes of the respective current values.

  The motor control device 1 shown in FIG. 1 is a non-insulated type in which the external control device 51 is connected via a common ground line. The motor control device 1 includes a motor drive circuit 2 for supplying a drive current A to a motor M, a motor control circuit 3 for outputting a control signal to the motor drive circuit 2, an internal ground line of the motor drive circuit 2 and the motor control circuit 3. It is equipped with four.

  In addition, motor control device 1 detects a current flowing through common ground line 5 connecting external control device 51 and internal ground line 4 and common ground line 5 and outputs a motor stop signal to motor control circuit 3. And a protection circuit 6.

  The motor drive circuit 2 is, for example, an H bridge circuit, and is connected to the power supply E by the power supply lines L1 and L2, and switches the flow direction of the drive current A to the motor M. The motor control circuit 3 is similarly connected to the power supply E by the power supply lines L1 and L2, and outputs a control signal such as an ON / OFF signal or a switching signal of the drive current A to the motor drive circuit 2. . A control circuit current B flows in the motor control circuit 3.

  Thus, the motor drive circuit 2 starts and stops the motor M in response to the ON / OFF signal from the motor control circuit 3, and performs normal rotation or reverse rotation of the motor M in response to the switching signal (control signal). The motor drive circuit 2 and the motor control circuit 3 are connected to the internal ground line 4. The internal ground line 4 is connected to the negative side of the power supply E via the power supply ground line L2.

  The common ground line 5 is connected to the internal ground line 4 and has an external terminal 5 a for connecting the ground line of the external control device 51. The protection circuit 6 will be described in detail later.

  The external control device 51 of this embodiment includes a main control circuit 51 A that controls the motor control circuit 3 in the motor control device 1. Main control circuit 51A includes power supply line L3. It is connected to the power supply E by L4 and has another ground line L5. A control circuit current C flows in the main control circuit 51A. When connected to the motor control device 1, the main control circuit 51 A connects the ground line L 5 to the external terminal 5 a of the commonization ground line 5. That is, in this embodiment, the internal ground line 4 and the common ground line 5 of the motor control device 1 are common ground lines with the external control device 51 (main control circuit 51A).

  As shown in the enlarged view in FIG. 1, when the current detection unit 10 detects the current from the internal ground line 4, the protection circuit 6 detects the current flowing through the common ground line 5 as shown in the enlarged view in FIG. 1. A first signal output unit 11 that outputs a motor stop signal to the motor control circuit 3 and a motor stop signal that is output to the motor control circuit 3 when the current detection unit 10 detects a current from the external control device 51 side. A two-signal output unit 12 is provided.

  More specifically, the protection circuit 6 has a configuration of a bidirectional current detection circuit. The current detection unit 10 includes a third resistor R3 provided on the common ground line 5, and a first resistor R1 and a second diode D2 connected to the side of the internal ground line 4 (right side in FIG. 1) of the third resistor R3. And a second resistor R2 and a first diode D1 connected to the external terminal 5a side of the third resistor R3.

  The first signal output unit 11 is a first transistor TR1 connected to the external terminal 5a side (left side in FIG. 1) of the third resistor R3, the first resistor R1 and the first diode D1. The second signal output unit 12 is a second transistor TR2 connected to the side of the internal ground line 4 of the third resistor R3 (right side in FIG. 1), the second resistor R2 and the second diode D2. The output signals of the first and second transistors TR1 and TR2 are both input to the motor control circuit 3.

  Further, as a more preferable embodiment, the protection circuit 6 has a threshold set based on the control circuit current B of the motor control circuit 3, and when the current value detected by the current detection unit 10 exceeds the threshold, The motor stop signal can be output by the one signal output unit 11 or the second signal output unit 12.

  In the protection circuit 6 described above, the third resistor R3 disposed on the common ground line 5 adds a margin to the maximum value of the current value assumed in the normal operation to form the first and second transistors TR1 and TR2. The resistance value does not exceed the threshold voltage. Thus, the protective circuit 6 holds both the first and second transistors TR1 and TR2 OFF in the normal operation. Further, since it is sufficient to flow a minute current flowing in the normal operation, the third resistor R3 hardly generates heat, so that it is not necessary to take a new heat countermeasure.

  The first and second transistors TR1 and TR2 output a signal for stopping the motor as an open collector. The threshold voltages of the transistors TR1 and TR2 are, for example, about 0.6 to 0.7V. Therefore, the operating voltage of the transistors TR1 and TR2 is sufficient by adding 1 V to the maximum value voltage of the signal for stopping the motor, and the current value of several mA or less is sufficient.

  In the state where the external control device 51 is connected, the motor control device 1 having the above configuration flows the drive current A of the motor M through the motor M and the motor drive circuit 2 as indicated by arrows in FIG. The control circuit current B of the motor control circuit 3 flows. Therefore, a total current (A + B) of the drive current A and the control circuit current B flows between the power supply lines L1 and L2 of the motor control device 1 and the power supply E. On the other hand, a control circuit current C flows in the main control circuit 51A of the external control device 51 via the power supply lines L3 and L4.

  Next, as shown in FIG. 2, in the motor control device 1, when a break (indicated by a cross) occurs in the power supply ground line L2, the external control device 51 is connected by the common ground line (4, 5). Therefore, the control circuit current B of the motor control circuit 3 flows into the common ground line 5 as an abnormal current.

  At this time, assuming that the motor control device 1 does not have the protection circuit 6, the control circuit current B of the motor control circuit 3 flows to the negative power supply line L4 via the ground line L5 of the external control device 51. Therefore, a total current (B + C) of the control circuit current B of the motor control circuit 3 and the control circuit current C of the external control device 51 flows through the power supply line L4. Then, in the motor control device 1, an offset voltage is generated in the motor instruction value due to the voltage drop of the ground line of the motor control device 1 and the external control device 51, and the motor M may operate abnormally.

  On the other hand, in the motor drive device 1, when a break (indicated by a cross) occurs in the power supply ground line L2, the control circuit current B of the motor control circuit 3 flows to the commonization ground line 5 as an abnormal current. The circuit 6 detects the control circuit current B, outputs a stop signal of the motor M to the motor control circuit 3, and stops the motor M via the motor drive circuit 2.

  That is, when the control circuit current B of the motor control circuit 3 is input to the protection circuit 6, the voltage on the internal ground line 4 side (the right side in the enlarged view in FIG. 1) of the third resistor R3 becomes high. When the first transistor TR1 is turned ON, a motor stop signal is output to the motor control circuit 3, and the motor M is stopped via the motor drive circuit 2. Thereby, the motor control device 1 can prevent the motor M from moving even if an offset voltage is generated in the command value of the motor M due to the voltage drop of the internal ground line 4 due to the disconnection of the power supply ground line L2.

  Further, assuming that the motor control device 1 does not have the protection circuit 6, when a break occurs in the power supply ground line L 2, the drive current A of the motor M passes through the commonization ground line 5 to ground the external control device 51. It flows to the line L5. At this time, since the common ground line 5 and the ground line L5 of the external control device 51 are lines for supplying the control circuit currents B and C having small current values, the drive current A of the motor M having a large current value is There is a risk of burning out.

  On the other hand, when a break occurs in the power supply ground line L2, the motor control device 1 operates the protection circuit 6 instantaneously to stop the motor M as described above. The drive current A (arrow A shown in FIG. 2) of the large motor M does not flow to the external control device 51 side. Thereby, the motor control device 1 can prevent burnout of the ground line L5 of the commonization ground line 5 and the external control device 51 in advance.

  Thus, in the non-insulated motor control device to which the external control device 51 is connected via the common ground line (4, 5), the motor control device 1 causes a break or the like in the power supply ground line L2. In this case, it is possible to prevent the occurrence of an abnormality caused by this.

  Further, since the motor control device 1 adopts the protection circuit 6 including the current detection unit 10 and the first and second signal output units 11 and 12, a simple and compact circuit configuration and a reliable protection function are realized. Thus, the protection function can be obtained inexpensively without the need to replace parts as in the case of a fuse.

  Furthermore, as apparent from FIG. 2, the motor control device 1 continues to flow the control circuit current B of the motor control circuit 3 even if the output of the motor M is turned off. Therefore, the motor control device 1 has a threshold value set based on the control circuit current B of the motor control circuit 3 in the protection circuit 6, and the current value detected by the current detection unit 10 exceeds the threshold value. The motor stop signal is output from the one signal output unit 11 or the second signal output unit 12. Thus, the motor control device 1 can always keep the output of the motor M in the OFF state at the time of abnormality such as disconnection of the power supply ground line L2.

  In the motor control device 1 described above, the protection circuit 6 includes the first and second signal output units 11 and 12 (first and second transistors TR1 and TR2). The direction of the control circuit current B flowing to the common ground line 5 is one direction. Therefore, the motor control device 1 of this embodiment can obtain the protection function even without the second signal output unit 12. However, in the second embodiment described below, it is clear that the protection circuit 6 described above sufficiently exerts its protection function, and the first and second signal output units 11 and 12 are provided. This is advantageous in achieving commonality of parts and improvement of versatility.

Second Embodiment
3 and 4 are diagrams for explaining an embodiment of a motor control system according to the present invention. The same components as those of the first embodiment are denoted by the same reference numerals and the detailed description thereof is omitted.

  The motor control system shown in FIG. 3 includes a plurality of motor control devices 1 configured by a motor drive circuit 2, a motor control circuit 3, an internal ground line 4, a common ground line 5, and a protection circuit 6.

  Then, in the motor control system, each motor control device 1 controls the motor M which is separate from each other, and is connected to the common power source E and the external control device 52. The external control device 52 of this embodiment is a potentiometer (volume). That is, in the illustrated motor control system, rotation control of the plurality of motors M is simultaneously performed by one external control device 52.

  In the external control device 52, the first terminal 52a is connected to the external terminal 5a of the common ground line 5 of each motor control device 1 via the ground line L5, and the second terminal 52b is a common line The third terminal 52 c is connected to the external terminal 5 b of each motor control device 1, and the third terminal 52 c is connected to the external terminal 5 c of the motor control device (upper stage) 1. Thus, the motor control devices 1 are mutually connected to the ground lines (4, 5) by the ground line L5 of the external control device 52.

  That is, in the motor control system of this embodiment, the internal ground line 4 and the commonization ground line 5 of each motor control device 1 are common ground lines with the external control device 52, and It is also a common ground line. Although two motor control devices 1 are shown in FIG. 3, the number of the motor control devices 1 is not limited, and two or more motor control devices 1 may be provided.

  The motor control system having the above configuration operates as follows when it is normal. That is, in the motor control device 1 at the upper stage in FIG. 3, the drive current A1 of the motor M flows to the motor M and the motor drive circuit 2, and the control circuit current B1 flows to the motor control circuit 2. Accordingly, in the power supply lines L1 and L2, a total current (A1 + B1) of the drive current A1 and the control circuit current B1 flows between the power supply E and the motor drive circuit 2.

  Further, in the motor control device 1 at the lower side in FIG. 3, the drive current A2 of the motor M flows through the motor M and the motor drive circuit 2 and the control circuit current B2 flows through the motor control circuit 2 similarly. A total current (A2 + B2) of the drive current A2 and the control circuit current B2 flows between the motor drive circuit 2 and the motor drive circuit 2.

  Next, the motor control system operates as follows at the time of abnormality shown in FIG. That is, in the motor control device 1 in the upper stage in FIG. 4, when a break (indicated by a cross) occurs in the power supply ground line L2, the control circuit current B1 of the motor control circuit 3 becomes an abnormal current and becomes a common ground line. 5 and the ground line L5 of the external control device 52, and further flows to the common ground line 5 and the internal ground line 4 of the normal motor control device 1 in the lower part of FIG.

  Thereby, in the normal motor control device 1 (lower stage), the total current of the control circuit current B1 of the motor control apparatus 1 (upper stage) in which the abnormality has occurred and its own control circuit current B2 in the internal ground line 4 B1 + B2) will flow.

  On the other hand, in the motor control device 1 (upper stage) in which the abnormality has occurred, the motor M is stopped by the protection circuit 6, and in the normal motor control device 1 (lower stage), the motor M is stopped by the protection circuit 6. Let At this time, in the motor control device 1 (upper stage) in which the abnormality has occurred and the normal motor control device 1 (lower stage), the flow directions of the currents in the respective protection circuits 6 are opposite to each other.

  At this time, in the protection circuit 6 of the motor control device 1 (upper stage) where the abnormality has occurred, the voltage on the internal ground line 4 side (right side in the enlarged view in FIG. 1) of the third resistor R3 as in the first embodiment. Becomes high, the first signal output unit 11 (first transistor TR1) is turned ON, and a motor stop signal is output to the motor control circuit 3. Thereby, the motor M is stopped via the motor drive circuit 2.

  On the other hand, in the protective circuit 6 of the normal motor control device 1 (lower stage), the voltage on the external terminal 5a side (left side in the enlarged view in FIG. 1) of the third resistor R3 becomes high. The second transistor TR2) is turned ON to output a motor stop signal to the motor control circuit 3. Thereby, the motor M is stopped via the motor drive circuit 2.

  In the motor control system, when a break or the like occurs in the power supply ground line L2 of the lower motor control unit 1 in FIG. 4, the total current before the internal ground line 4 of the upper normal motor control unit 1 (B1 + B2) flows. Thereby, the flow direction of the control circuit current (abnormal current) to each protection circuit 6 is reverse to the direction of the arrow shown in FIG. 4, but in any motor control device 1, the protection circuit 6 similarly Function to stop the motor M.

  The motor control system described above stops all motors M immediately in any motor control device 1 even if the power supply ground line L2 is disconnected, and the voltage drop of the internal ground line 4 causes the indicated value of the motor M to be reduced. Make sure that no offset voltage occurs.

  Further, in the motor control system described above, as in the previous embodiment, even when the power supply ground line L2 of any of the motor control devices 1 is disconnected, the protection circuit 6 operates instantaneously to set the motor M Stop immediately. Therefore, actually, the drive current A (arrow A shown in FIG. 4) of the motor M having a large current value does not flow to the external control device 51 side.

  Thus, the motor control system includes a plurality of motor control devices 1 that control the individual motors M using the common power supply E, and the external control device 52 is connected via the common ground lines (4, 5). In the configuration described above, when a break or the like occurs in the power supply ground line L2, occurrence of an abnormality such as an abnormal operation of the motor M or a burnout of the ground line L5 due to the disconnection is prevented beforehand.

  Further, the motor control device described above adopts the protection circuit 6 including the current detection unit 10 and the first and second signal output units 11 and 12, so that the control circuit current input to the protection circuit 6 (abnormal Since the motor stop signal can be output even if the direction of the current changes, it is more preferable as a protective function in the configuration provided with a plurality of motor control devices 1.

  The configurations of the motor control device and the motor control system of the present invention are not limited to the above embodiments, and the details of the configuration can be changed as appropriate without departing from the scope of the present invention. For example, the specific circuit configuration of the protection circuit can also be changed.

1 Motor control device 2 Motor drive circuit 3 Motor control circuit 4 Internal ground line (common ground line)
5 Common ground line (common ground line)
6 Protection circuit 10 Current detection unit 11 First signal output unit 12 Second signal output unit 51, 52 External control device A, A1, A2 Motor drive current B, B1, B2 Control circuit current C External control device control circuit current E Power supply M motor

Claims (4)

A motor control device to which an external control device is connected via a common ground line,
A motor drive circuit for supplying a drive current to the motor;
A motor control circuit that outputs a control signal to the motor drive circuit;
An internal ground line of the motor drive circuit and the motor control circuit,
Common ground line connecting external control equipment and internal ground line,
What is claimed is: 1. A motor control apparatus comprising: a protection circuit that detects a current flowing in a common ground line and outputs a motor stop signal to a motor control circuit. The protection circuit is
A current detection unit that detects the current flowing to the common ground line;
A first signal output unit that outputs a motor stop signal to the motor control circuit when the current detection unit detects a current from the internal ground line side;
The motor control device according to claim 1, further comprising: a second signal output unit that outputs a motor stop signal to the motor control circuit when the current detection unit detects a current from the external control device side. . The protection circuit is
It has a threshold set based on the control circuit current of the motor control circuit, and when the current value detected by the current detector exceeds the threshold, the motor stop signal is output by the first signal output unit or the second signal output unit The motor control device according to claim 2, wherein: A plurality of motor control devices according to any one of claims 1 to 3
A motor control system, wherein each motor control device controls each other's motor and is connected to a common power source and an external control device.

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