JP7351214B2 - Motor control device, electronic equipment, and failure detection method - Google Patents

Description

The present invention relates to a motor control device, an electronic device, and a failure detection method.

Patent Document 1 below discloses that for the purpose of detecting a failure of a motor control device having an H-bridge circuit, when the H-bridge circuit is in a driving state, the terminal voltage on the high potential side detected by a motor terminal voltage detection circuit is A technique has been disclosed in which it is determined that a ground fault has occurred at a motor terminal when the voltage falls below a driving threshold that changes in proportion to the power supply voltage and the duty ratio of PWM control.

However, with the prior art, it is not possible to determine whether the fault is a ground fault in the harness connecting the H-bridge circuit and the DC motor or a fault in the H-bridge circuit.

In order to solve the above-mentioned problems of the prior art, the present invention aims to make it possible to determine whether the fault is a ground fault in the harness connecting the H-bridge circuit and the DC motor or a fault in the H-bridge circuit. purpose.

In order to solve the above problems, a motor control device of the present invention includes a first transistor and a second transistor connected in series between a power source and ground, and a first transistor and a second transistor connected in series between a power source and ground. An H-bridge circuit that has a third transistor and a fourth transistor, and controls the operation of the DC motor by controlling the switching of these four transistors, and the first transistor and the second transistor. a first voltage detection unit that detects a voltage value between the first connection point and ground as the first voltage value; and a second connection point between the third transistor and the fourth transistor. a second voltage detection unit that detects a voltage value between the ground and the ground as a second voltage value; and a voltage value between the third connection point between the second transistor and the fourth transistor and the ground. A third voltage detection unit detects the voltage as a third voltage value, and a current path from the H-bridge circuit to the DC motor based on the first voltage value, the second voltage value, and the third voltage value. and a failure detection unit that determines a generated failure according to the type of failure, and the failure detection unit detects a current based on the first voltage value and the second voltage value when all four transistors are in the off state. A first failure determination process is performed to determine a failure occurring in the road according to the type of failure, and in the first failure determination process, when both the first voltage value and the second voltage value are equal to or less than a predetermined threshold value. Based on the third voltage value when current is supplied from the H-bridge circuit to the DC motor, it is determined whether there is a ground fault in the harness connecting the H-bridge circuit and the DC motor, or there is a failure in the H-bridge circuit. A second failure determination process is performed to determine whether the

According to the present invention, it is possible to determine whether the fault is a ground fault in the harness connecting the H-bridge circuit and the DC motor or a fault in the H-bridge circuit.

A diagram showing the configuration of an electronic device according to an embodiment of the present invention A diagram showing an example of failure determination criteria used in a failure detection device according to an embodiment of the present invention. A diagram showing an example of failure determination criteria used in a failure detection device according to an embodiment of the present invention. A flowchart showing an example of a processing procedure by a failure detection device according to an embodiment of the present invention A diagram showing a normal state of a motor control device according to an embodiment of the present invention A diagram showing a state of a motor control device according to an embodiment of the present invention when a harness ground fault occurs A diagram showing a state of a motor control device according to an embodiment of the present invention when a motor disconnection occurs. A diagram showing a state of a motor control device according to an embodiment of the present invention when an H-bridge circuit fails. A diagram illustrating the state of the motor control device according to an embodiment of the present invention when the H-bridge circuit fails and when the second determination process is performed. A diagram illustrating the state of the motor control device according to an embodiment of the present invention when a harness ground fault occurs and when the second determination process is performed. A diagram showing a state of the motor control device according to an embodiment of the present invention when the H-bridge circuit fails and when the DC motor rotates in the forward direction. A diagram illustrating a state of a motor control device according to an embodiment of the present invention when the H-bridge circuit fails and when the DC motor rotates in reverse.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

(Configuration of electronic device 1)
FIG. 1 is a diagram showing the configuration of an electronic device 1 according to an embodiment of the present invention. The electronic device 1 shown in FIG. 1 includes a motor control device 10 and a DC motor 20. The motor control device 10 controls the rotation operation (rotation speed, rotation direction, rotation angle, etc.) of a rotation shaft (not shown) included in the DC motor 20 . The DC motor 20 realizes one function of the electronic device 1 by rotating a rotating member (not shown) included in the electronic device 1 . Note that the electronic device 1 may be any electronic device as long as it includes at least a rotating member that is rotated by the drive of the DC motor 20.

As shown in FIG. 1, the motor control device 10 includes an H-bridge circuit 12, a voltage detection circuit 16, and a failure detection device 18.

The H-bridge circuit 12 includes four transistors Tr1 to Tr4.

The first transistor Tr1 and the second transistor Tr2 are connected in series between the power supply PW and ground. The first transistor Tr1 is provided on the power supply PW side. The second transistor Tr2 is provided on the ground side. One end of the DC motor 20 is connected via a harness 22 to a connection point P1 (an example of a "first connection point") between the first transistor Tr1 and the second transistor Tr2.

The third transistor Tr3 and the fourth transistor Tr4 are connected in series between the power supply PW and ground. The third transistor Tr3 is provided on the power supply PW side. The fourth transistor Tr4 is provided on the ground side. The other end of the DC motor 20 is connected via a harness 22 to a connection point P2 (an example of a "second connection point") between the third transistor Tr3 and the fourth transistor Tr4.

The H-bridge circuit 12 controls the supply of current to the DC motor 20 and the direction of the current flowing through the DC motor 20 by controlling the switching of four transistors Tr1 to Tr4 from a host controller (not shown). can do. Thereby, the H-bridge circuit 12 can rotate the rotating shaft of the DC motor 20 in two directions in different rotational directions.

Voltage detection circuit 16 has resistors R1 to R6. The resistor R1 has one end connected to the connection point P5 between the power supply PW and the third transistor Tr3, and the other end connected to the connection point P2 between the third transistor Tr3 and the fourth transistor Tr4. and the harness 22 at a connection point P6.

Resistor R2 and resistor R3 are connected in series between connection point P6 and ground. The resistor R2 is provided on the connection point P6 side. Resistor R3 is provided on the ground side. A failure detection device 18 is connected to a detection point P9 between the resistors R2 and R3. The failure detection device 18 is supplied with a signal SC1 that represents the voltage value detected at the detection point P9 as a "second voltage value." Resistor R2 and resistor R3 constitute a "second voltage detection section".

Resistor R4 and resistor R5 are connected in series between connection point P7 and ground. The connection point P7 is provided between the harness 22 and the connection point P1 between the first transistor Tr1 and the second transistor Tr2. The resistor R4 is provided on the connection point P7 side. Resistor R5 is provided on the ground side. A failure detection device 18 is connected to a detection point P8 between the resistors R4 and R5. The failure detection device 18 is supplied with a signal SC2 that represents the voltage value detected at the detection point P8 as a "first voltage value." Resistor R4 and resistor R5 constitute a "first voltage detection section".

The resistor R6 is provided between a connection point P3 (an example of a "third connection point") between the second transistor Tr2 and the fourth transistor Tr4 in the H-bridge circuit 12, and the ground. A failure detection device 18 is connected to a detection point P10 between the connection point P3 and the resistor R6. The failure detection device 18 is supplied with a signal IS that represents the voltage value detected at the detection point P10 as a "third voltage value." Resistor R6 constitutes a "third voltage detection section".

The failure detection device 18 is an example of a "failure detection unit." The failure detection device 18 detects signals from the H-bridge circuit 12 to the DC motor 20 based on the signal SC1 supplied from the detection point P9, the signal SC2 supplied from the detection point P8, and the signal IS supplied from the detection point P10. It is possible to detect failures that have occurred up to this point by type of failure. The voltage detection circuit 16 is realized by, for example, an IC (Integrated Circuit), a microcomputer, or the like.

(Example of failure judgment criteria)
2 and 3 are diagrams illustrating an example of failure determination criteria used in the failure detection device 18 according to an embodiment of the present invention.

As a first failure determination process, the failure detection device 18 detects the logical value of the signal SC1 and the signal when all four transistors Tr1 to Tr4 of the H-bridge circuit 12 are in the off state before the DC motor 20 operates. Based on the logical value of SC2 and the failure determination criteria shown in FIG. 2, failures occurring between the H-bridge circuit 12 and the DC motor 20 are detected by type of failure.

Note that the ethical values of the signals SC1 and SC2 can be "H (High)" or "L (Low)". "H" can be taken when the voltage values of the signals SC1 and SC2 are equal to or higher than a predetermined voltage threshold determined in advance. "L" can be taken when the voltage values of the signals SC1 and SC2 are less than a predetermined voltage threshold determined in advance. The predetermined voltage threshold value determined in advance is stored in advance in a memory provided with the predetermined voltage threshold value.

For example, if the logical value of the signal SC1 is "H" and the logical value of the signal SC2 is "H", the failure detection device 18 determines that the signal is "normal" according to the failure determination criteria shown in FIG. do.

Further, for example, when the logical value of the signal SC1 is “L” and the logical value of the signal SC2 is “L”, the failure detection device 18 detects the “harness ground” according to the failure determination criteria shown in FIG. It is determined that the fault is caused by a circuit failure or an H-bridge circuit failure. In this case, the failure detection device 18 determines whether it is a "harness ground fault" or an "H bridge circuit failure" by performing a second failure determination process.

Further, for example, when the logical value of the signal SC1 is "H" and the logical value of the signal SC2 is "L", the failure detection device 18 detects "motor disconnection" according to the failure determination criteria shown in FIG. It is judged as 'failure'.

Further, for example, when the logical value of the signal SC1 is "L" and the logical value of the signal SC2 is "H", the failure detection device 18 detects "other failures" according to the failure determination criteria shown in FIG. ”.

Furthermore, when the failure detection device 18 determines in the first failure determination process that it is a "harness ground fault" or "H bridge circuit failure", it performs a second failure determination process. In the second failure determination process, the failure detection device 18 turns on the first transistor Tr1 and the fourth transistor Tr4, or turns on the second transistor Tr2 and the third transistor Tr3. Switch. Then, based on the voltage value of the signal IS supplied from the detection point P10, the failure detection device 18 determines whether it is a "harness ground fault" or an "H bridge circuit failure" according to the failure determination criteria shown in FIG. Determine if there is.

For example, in the second failure determination process, if the voltage value of the signal IS is other than 0V, the failure detection device 18 determines that there is an "H bridge circuit failure" according to the failure determination criteria shown in FIG.

Further, for example, in the second failure determination process, if the voltage value of the signal IS is 0V, the failure detection device 18 determines that it is a "harness ground fault failure" according to the failure determination criteria shown in FIG.

(Example of processing procedure by failure detection device 18)
FIG. 4 is a flowchart showing an example of a processing procedure by the failure detection device 18 according to an embodiment of the present invention.

First, when the failure detection device 18 confirms that the DC motor 20 is in a stopped state (step S401), it acquires the signal SC1 supplied from the detection point P9 and the signal SC2 supplied from the detection point P8 ( Step S402).

Next, the failure detection device 18 determines whether the condition that "the logical value of the signal SC1 is 'H' and the logical value of the signal SC2 is 'H'" is satisfied (step S403). .

In step S403, if it is determined that the conditions are satisfied (step S403: Yes), the failure detection device 18 determines that the condition is "normal" (step S404), and ends the series of processes shown in FIG.

On the other hand, if it is determined in step S403 that the conditions are not satisfied (step S403: No), the failure detection device 18 detects that "the logical value of signal SC1 is "H" and the logical value of signal SC2 is " It is determined whether the condition "L" is satisfied (step S405).

In step S405, if it is determined that the condition is satisfied (step S405: Yes), the failure detection device 18 determines that it is a "motor disconnection failure" (step S406), and ends the series of processes shown in FIG. 4.

In step S405, if it is determined that the conditions are not satisfied (step S405: No), the failure detection device 18 detects that "the logical value of the signal SC1 is "L" and the logical value of the signal SC2 is "H". It is determined whether the condition "is satisfied" (step S407).

In step S407, if it is determined that the condition is satisfied (step S407: Yes), the failure detection device 18 determines that it is an "other failure" (step S408), and ends the series of processes shown in FIG. 4.

On the other hand, if it is determined in step S407 that the condition is not satisfied (step S407: No), the failure detection device 18 switches the first transistor Tr1 and the fourth transistor Tr4 to the on state, or By switching the second transistor Tr2 and the third transistor Tr3 to the on state, the control state of the motor by the H bridge circuit 12 is switched to the on state (step S409).

The failure detection device 18 then determines whether the voltage value of the signal IS supplied from the detection point P10 is 0V (step S410).

If it is determined in step S410 that the voltage value of the signal IS is 0V (step S410: Yes), the failure detection device 18 determines that there is a "harness ground fault" (step S411). The failure detection device 18 then ends the series of processes shown in FIG.

On the other hand, if it is determined in step S410 that the voltage value of the signal IS is not 0V (step S410: No), the failure detection device 18 determines that there is an "H bridge circuit failure" (step S412). The failure detection device 18 then ends the series of processes shown in FIG.

(Status of motor control device 10: normal)
FIG. 5 is a diagram showing a normal state of the motor control device 10 according to an embodiment of the present invention. As shown in FIG. 5, when the DC motor 20 is in a stopped state (that is, when all four transistors are in an off state) and when no abnormality has occurred between the motor control device 10 and the DC motor 20, A current is supplied from the power source PW to the wiring between the connection point P1 and the connection point P2 via the resistor R1.

Therefore, a current flows from the connection point P6 on the wiring between the connection point P1 and the connection point P2 to the ground via the resistors R2 and R3. Therefore, at the detection point P9 between the resistor R2 and the resistor R3, a voltage equal to or higher than a predetermined threshold is generated, and therefore, the logic value of the signal SC1 supplied from the detection point P9 becomes "H".

Similarly, a current flows from the connection point P7 on the wiring between the connection point P1 and the connection point P2 to the ground via the resistors R4 and R5. Therefore, at the detection point P8 between the resistor R4 and the resistor R5, a voltage equal to or higher than a predetermined threshold is generated, and therefore, the logic value of the signal SC2 supplied from the detection point P8 becomes "H".

Therefore, the failure detection device 18 determines that the DC motor 20 is "normal" when the logical value of the signal SC1 is "H" and the logical value of the signal SC2 is "H" when the DC motor 20 is in a stopped state. can do.

(Status of motor control device 10: At the time of harness ground fault)
FIG. 6 is a diagram showing a state of the motor control device 10 according to an embodiment of the present invention at the time of a harness ground fault. A harness ground fault is a fault in which the harness 22 is shorted to ground.

As shown in FIG. 6, when the DC motor 20 is in the stopped state (that is, when all four transistors are in the off state) and when a harness ground fault has occurred, the power is supplied from the power source PW via the resistor R1. The current supplied to the wiring between the connection point P1 and the connection point P2 flows to the ground from the harness ground fault location.

Therefore, almost no current flows through the wiring from the connection point P6 to the ground via the resistors R2 and R3, and therefore, no voltage higher than a predetermined threshold is generated at the detection point P9 on this wiring. The logical value of the signal SC1 supplied from the detection point P9 is "L".

Similarly, almost no current flows in the wiring from the connection point P7 to the ground via the resistors R4 and R5, so at the detection point P8 on this wiring, no voltage higher than the predetermined threshold is generated. The logical value of the signal SC2 supplied from the detection point P8 is "L".

Therefore, when the DC motor 20 is in a stopped state and the logical value of the signal SC1 is "L" and the logical value of the signal SC2 is "L", the failure detection device 18 detects a "harness ground fault fault". ” can be determined.

(Status of motor control device 10: At the time of motor disconnection failure)
FIG. 7 is a diagram showing a state of the motor control device 10 according to an embodiment of the present invention at the time of a motor disconnection failure. The motor disconnection failure is a failure in which a coil or the like of the DC motor 20 is disconnected.

As shown in FIG. 7, when the DC motor 20 is in a stopped state (that is, when all four transistors are in an off state) and when a motor disconnection fault has occurred, a connection is made from the power supply PW via the resistor R1. The current supplied to the wiring between the point P1 and the connection point P2 flows upstream of the DC motor 20 (on the connection point P2 side) in the wiring between the connection point P1 and the connection point P2. It does not flow downstream from the DC motor 20 (to the connection point P1 side).

Therefore, a current flows from the connection point P6 located upstream of the DC motor 20 to the ground via the resistors R2 and R3. Therefore, at the detection point P9 between the resistor R2 and the resistor R3, a voltage equal to or higher than a predetermined threshold is generated, and therefore, the logic value of the signal SC1 supplied from the detection point P9 becomes "H".

On the other hand, almost no current flows in the wiring from the connection point P7 downstream of the DC motor 20 to the ground via the resistors R4 and R5. Therefore, the logical value of the signal SC2 supplied from the detection point P8 becomes "L".

Therefore, when the DC motor 20 is in a stopped state, the failure detection device 18 detects a "motor disconnection failure" when the logical value of the signal SC1 is "H" and the logical value of the signal SC2 is "L". It can be determined that

(Status of motor control device 10: At the time of H bridge circuit failure)
FIG. 8 is a diagram showing a state of the motor control device 10 when the H-bridge circuit fails according to an embodiment of the present invention. The H-bridge circuit failure is, for example, a failure in which any of the four transistors included in the H-bridge circuit 12 is short-circuited.

For example, as shown in FIG. 8, when the DC motor 20 is in a stopped state (that is, when all four transistors are in an off state), and when the fourth transistor Tr4 included in the H bridge circuit 12 is short-circuited. A current supplied from the power source PW to the wiring between the connection point P1 and the connection point P2 via the resistor R1 flows out to the ground via the fourth transistor Tr4.

Therefore, almost no current flows through the wiring from the connection point P6 to the ground via the resistors R2 and R3, and therefore, no voltage higher than a predetermined threshold is generated at the detection point P9 on this wiring. The logical value of the signal SC1 supplied from the detection point P9 is "L".

Similarly, almost no current flows in the wiring from the connection point P7 to the ground via the resistors R4 and R5, so at the detection point P8 on this wiring, no voltage higher than the predetermined threshold is generated. The logical value of the signal SC2 supplied from the detection point P8 is "L".

Therefore, when the DC motor 20 is in a stopped state and the logical value of the signal SC1 is "L" and the logical value of the signal SC2 is "L", the failure detection device 18 detects an "H bridge circuit failure". ” can be determined.

However, also in the case of the "harness ground fault" shown in FIG. 6, the logical value of the signal SC1 is "L" and the logical value of the signal SC2 is "L". Therefore, the failure detection device 18 cannot determine whether it is an "H-bridge circuit failure" or a "harness ground fault" only by the first determination process. Therefore, the failure detection device 18 can determine whether it is an "H bridge circuit failure" or a "harness ground fault" by further performing a second determination process.

(Status of motor control device 10: At the time of H bridge circuit failure and at the time of second determination processing)
FIG. 9 is a diagram illustrating a state of the motor control device 10 according to an embodiment of the present invention when the H-bridge circuit fails and when the second determination process is performed.

For example, during the second determination process, as shown in FIG. 9, the failure detection device 18 detects a set of transistors (in the example shown in FIG. 9, the first transistor Tr1 and the fourth transistor Tr4) are turned on.

Here, as shown in FIG. 9, when a short-circuit failure occurs in the fourth transistor Tr4 included in the H-bridge circuit 12, the power is supplied from the power source PW to the DC motor 20 via the first transistor Tr1. The current flows to ground via the fourth transistor Tr4, the connection point P3, and the resistor R6. Therefore, a voltage is generated at the detection point P10 between the connection point P3 and the resistor R6.

Therefore, in the second determination process, if the signal IS supplied from the detection point P10 has a voltage value (that is, not 0 V), the failure detection device 18 determines that there is an "H bridge circuit failure". I can do it.

(Status of motor control device 10: At the time of harness ground fault failure and at the time of second determination processing)
FIG. 10 is a diagram showing a state of the motor control device 10 according to an embodiment of the present invention at the time of a harness ground fault and at the time of the second determination process.

For example, during the second determination process, as shown in FIG. 10, the failure detection device 18 detects a set of transistors (in the example shown in FIG. 10, the first transistor Tr1 and the fourth transistor Tr4) are turned on.

Here, as shown in FIG. 10, when a harness ground fault occurs, the current supplied from the power source PW to the DC motor 20 via the first transistor Tr1 flows out from the harness ground fault to the ground. do. Therefore, no current flows in the wiring from the connection point P3 to the ground via the resistor R6, and therefore no voltage is generated at the detection point P10 between the connection point P3 and the resistor R6.

Therefore, during the second determination process, the failure detection device 18 determines that there is a "harness ground fault" when the signal IS supplied from the detection point P10 has no voltage value (that is, when it is 0V). be able to.

(How to identify a malfunctioning transistor)
Note that during the second determination process, the failure detection device 18 uses the voltage value (third voltage value) of the signal IS when the DC motor 20 is rotated in the forward direction and the voltage value (third voltage value) when the DC motor 20 is rotated in the reverse direction. Based on the voltage value (third voltage value) of the signal IS, it is possible to determine which transistor has failed in the H-bridge circuit 12.

For example, FIG. 11 is a diagram illustrating a state of the motor control device 10 according to an embodiment of the present invention when the H-bridge circuit fails and when the DC motor 20 rotates in the forward direction. As shown in FIG. 11, when a short-circuit failure occurs in the fourth transistor Tr4, when the first transistor Tr1 and the fourth transistor Tr4 are turned on and the DC motor 20 is rotated in the forward direction, Since the resistance value of the transistor Tr4 of No. 4 is different from the predetermined resistance value, the voltage value detected at the detection point P10 is different from the target voltage value.

On the other hand, FIG. 12 is a diagram showing a state of the motor control device 10 according to an embodiment of the present invention when the H-bridge circuit fails and when the DC motor 20 rotates in reverse. As shown in FIG. 12, when a short-circuit failure occurs in the fourth transistor Tr4, when the second transistor Tr2 and the third transistor Tr3 are turned on and the DC motor 20 is reversely rotated, Since the resistance value of the transistor Tr4 of No. 4 becomes a predetermined resistance value, the voltage value detected at the detection point P10 becomes the target voltage value.

Therefore, during the second determination process, the failure detection device 18 causes the DC motor 20 to rotate forward and reverse, so that the voltage value of the signal IS supplied from the detection point P10 becomes different from the target voltage value. At this time, it can be determined that the transistor on the current path from the DC motor 20 to the ground is malfunctioning.

As described above, the failure detection device 18 according to the embodiment of the present invention detects the first voltage value represented by the signal SC1 and the second voltage value represented by the signal SC2 when all four transistors Tr1 to Tr4 are in the off state. Based on the voltage value of , a first failure determination process is performed in which failures occurring in the current path from the H-bridge circuit 12 to the DC motor 20 are determined by type of failure. Then, in the first failure determination process, the failure detection device 18 according to one embodiment of the present invention detects the Based on the third voltage value represented by the signal IS when current is supplied to the DC motor, it is determined whether there is a ground fault in the harness 22 that connects the H-bridge circuit 12 and the DC motor 20, or whether there is a ground fault in the H-bridge circuit 12. A second failure determination process is performed to determine whether there is a failure.

Thereby, the failure detection device 18 according to an embodiment of the present invention determines whether the failure is a ground fault in the harness 22 connecting the H-bridge circuit 12 and the DC motor 20 or a failure in the H-bridge circuit 12. can do.

Further, in the failure detection device 18 according to an embodiment of the present invention, in the second failure determination process, if the third voltage value is 0V, the failure detection device 18 determines that there is a ground fault failure in the harness 22, If the third voltage value is not 0V, it can be determined that the H-bridge circuit 12 has failed.

As a result, the failure detection device 18 according to an embodiment of the present invention determines whether it is a ground fault in the harness 22 or a failure in the H-bridge circuit 12, depending on whether the third voltage value is 0V. can be determined.

Furthermore, in the failure detection device 18 according to an embodiment of the present invention, in the second failure determination process, the failure detection device 18 detects a third voltage value when the DC motor 20 is rotated in the forward direction, and a third voltage value when the DC motor 20 is rotated in the forward direction. It is possible to determine which transistor among the four transistors Tr1 to Tr4 is in failure based on the third voltage value obtained when the transistors are reversely rotated.

Thereby, the failure detection device 18 according to the embodiment of the present invention can simplify the determination of the location of the failure by the failure responder, so that the failure responder can quickly respond to the failure.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments, and various modifications and variations can be made within the scope of the gist of the present invention as described in the claims. Changes are possible.

1 Electronic equipment 10 Motor control device 12 H bridge circuit 16 Voltage detection circuit 18 Failure detection device (failure detection unit)
20 DC motor 22 Harness P1 to P7 Connection points P8 to P10 Detection points R1 to R6 Resistance Tr1 First transistor Tr2 Second transistor Tr3 Third transistor Tr4 Fourth transistor

JP2002-204593A

Claims (6)

It has a first transistor and a second transistor connected in series between the power supply and the ground, and a third transistor and a fourth transistor connected in series between the power supply and the ground, and these four transistors are connected in series between the power supply and the ground. an H-bridge circuit that controls the operation of a DC motor by controlling the switching of transistors;
a first voltage detection unit that detects a voltage value between a first connection point between the first transistor and the second transistor and ground as a first voltage value;
a second voltage detection unit that detects a voltage value between a second connection point between the third transistor and the fourth transistor and ground as a second voltage value;
a third voltage detection unit that detects a voltage value between a third connection point between the second transistor and the fourth transistor and ground as a third voltage value;
A failure that occurs in a current path from the H-bridge circuit to the DC motor is determined by type of failure based on the first voltage value, the second voltage value, and the third voltage value. Equipped with a detection part and
The failure detection section includes:
a first failure determination process of determining a failure occurring in the current path by type of failure based on the first voltage value and the second voltage value when all of the four transistors are in an off state; and
In the first failure determination process, if both the first voltage value and the second voltage value are below a predetermined threshold value, the Based on the voltage value of step 3, a second failure determination process is performed to determine whether the failure is a ground fault in a harness connecting the H-bridge circuit and the DC motor or a failure in the H-bridge circuit. A motor control device characterized by: The failure detection section includes:
In the second failure determination process, if the third voltage value is 0V, it is determined that there is a ground fault in the harness, and if the third voltage value is not 0V, it is determined that the H-bridge circuit has failed. The motor control device according to claim 1, characterized in that: The failure detection section includes:
In the second failure determination process, based on the third voltage value when the DC motor is rotated in the forward direction and the third voltage value when the DC motor is rotated in the reverse direction, the The motor control device according to claim 2, further comprising: determining which transistor has a failure among the two transistors. The failure detection section includes:
When the third voltage value does not reach a predetermined target voltage value when the DC motor is rotated forward or reverse, a transistor provided on the current path from the DC motor to the ground is caused to malfunction. 4. The motor control device according to claim 3, wherein the motor control device is determined to be a transistor in which . An electronic device comprising: the DC motor; and the motor control device according to any one of claims 1 to 4. It has a first transistor and a second transistor connected in series between the power supply and the ground, and a third transistor and a fourth transistor connected in series between the power supply and the ground, and these four transistors are connected in series between the power supply and the ground. A failure detection method for determining failures occurring in a current path from an H-bridge circuit that controls the operation of a DC motor to the DC motor by type of failure by controlling switching of a transistor,
a first voltage value that is a voltage value between a first connection point between the first transistor and the second transistor and ground when all of the four transistors are in an off state; A fault occurring in the current path is determined based on a second voltage value that is a voltage value between a second connection point between the third transistor and the fourth transistor and the ground. a first failure determination process for performing a first failure determination process for determining each type;
In the first failure determination processing step, if both the first voltage value and the second voltage value are below a predetermined threshold, the connecting the H-bridge circuit and the DC motor based on a third voltage value that is a voltage value between a third connection point between the second transistor and the fourth transistor and ground; A second failure determination processing step of performing a second failure determination process for determining whether it is a ground fault in a harness or a failure in the H-bridge circuit.

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