JP2010148274A - Motor control apparatus and electric power steering arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress relay wear as much as possible without impairing the function of the relay. <P>SOLUTION: When a system pre-trigger check of a motor control apparatus is started, a control circuit 31 executes an abnormality determination process by turning on a relay 15 for an electric motor to determine whether the relay is abnormal. If no abnormality is found with the abnormality determination process, the system of the motor control apparatus is triggered. If an abnormality is found with the abnormality determination process while the number of times of executing the determination process is less than a predetermined number of times, the relay 15 is turned off to execute the abnormality determination process again. If abnormality is found with the abnormality determination process while the number of times of executing the determination process is equal to or more than a predetermined number of times, the relay 15 is turned on/off repeatedly for a predetermined period of time, and then the abnormality determination process is executed again. If there exists abnormality with the relay 15, the system of the motor control apparatus is stopped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device and an electric power steering device.

  The electric power steering device of an automobile assists the driver's steering by using the driving force of the electric motor controlled by the motor control device. The electric motor used in the electric power steering apparatus starts its operation after the relay for the electric motor is turned on when the automobile is started and control by the motor control apparatus becomes possible.

Incidentally, dust or the like may adhere to the relay contact for the electric motor or an oxide film may be formed. In such a case, the relay for the electric motor cannot function normally, and as a result, the electric motor cannot be operated. Therefore, in the motor control device described in Patent Document 1 below, before starting the system, the relay is repeatedly turned on and off a predetermined number of times to remove dust and the like attached to the relay contacts.
JP 2005-253156 A

  However, in the conventional technique, before starting the system, the relay is unconditionally repeatedly turned on / off several times each time. Therefore, for example, when dust or the like is not attached to the relay contact or when dust or the like is removed immediately, the relay is repeatedly turned on and off unnecessarily. When the relay is repeatedly turned on and off, the wear of the relay advances and the life is shortened. It is also conceivable that once the relay is turned on / off, dust once removed will adhere to the relay contact again.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a motor control device and an electric power steering device that can suppress the consumption of the relay as much as possible without impairing the function of the relay.

  In order to achieve the above object, a motor control device according to the present invention includes a control unit that controls an electric motor for a vehicle, and a motor relay that turns on / off a connection between the control unit and the electric motor. Before starting control of the electric motor, the control unit turns on the motor relay and executes an abnormality determination process for determining whether or not the motor relay has an abnormality. When it is determined that there is no abnormality, control of the electric motor is started, and when it is determined that there is an abnormality in the abnormality determination process, the abnormality determination process is executed again after the motor relay is turned off.

  When such a configuration is adopted, it is possible to determine whether or not the motor relay has an abnormality at least once before starting the control of the electric motor. If there is an abnormality, the relay is turned on / off. The deposits on the relay contacts can be removed. On the other hand, if there is no abnormality, the control of the electric motor can be started as it is. Therefore, the consumption of the relay can be suppressed as much as possible without impairing the function of the relay.

  In the motor control device, the control unit counts the number of times the abnormality determination process has been performed as the number of determination process executions, and determines that the abnormality determination process has an abnormality, and the number of determination process executions is a predetermined number. When the upper limit number has been reached, the abnormality determination process can be executed after the motor relay is repeatedly turned on / off for a predetermined time.

  As a result, the number of executions of the abnormality determination process can be limited, and the relay can be turned on / off repeatedly for a predetermined time even when the deposit cannot be removed only by the on / off operation during the abnormality determination process. Since the abnormality determination process can be executed after that, the deposits can be more reliably removed.

  In the motor control device, the control unit measures the time elapsed since the start of the execution of the abnormality determination process as an elapsed time, and determines that there is an abnormality in the abnormality determination process, and the elapsed time When the predetermined upper limit time has been reached, the abnormality determination process can be executed after repeating the ON / OFF of the motor relay for a predetermined time.

  As a result, the execution time of the abnormality determination process can be limited, and the relay is turned on / off repeatedly for a predetermined time even when the deposit cannot be removed only by the on / off operation during the abnormality determination process. Since the abnormality determination process can be executed after that, the deposits can be more reliably removed.

  In the motor control device, the control unit may stop the control of the electric motor when it is determined that there is an abnormality in the abnormality determination process executed after the motor relay is turned on / off repeatedly for a predetermined time. it can.

  Thereby, when the deposit | attachment which cannot be removed even if ON / OFF is repeated for a predetermined time has adhered, control of an electric motor can be stopped.

  In the motor control device, if the control unit determines that there is an abnormality in the abnormality determination process that is executed after the on / off of the motor relay is repeated for a predetermined time, the potential difference between the contacts of the motor relay is calculated. The abnormality determination process can be executed after setting a predetermined potential difference that may cause arc discharge.

  As a result, when the deposit cannot be removed even if the relay is turned on and off for a predetermined time, the deposit can be removed using arc discharge, so that the deposit can be more reliably removed. It can be removed.

  In the motor control device, the control unit stops the control of the electric motor when it is determined that there is an abnormality in the abnormality determination process performed after setting the potential difference between the contacts of the motor relay to a predetermined potential difference. be able to.

  Thereby, when the deposit | attachment which cannot be removed even if it uses arc discharge has adhered, control of an electric motor can be stopped.

  In the motor control device, when the controller determines that there is an abnormality in the abnormality determination process, the abnormality determination process is performed after setting the potential difference between the contacts of the motor relay to a predetermined potential difference that can cause arc discharge. Can be executed.

  Thereby, when it is determined that there is an abnormality in the abnormality determination process, the deposit can be removed using arc discharge, so that the deposit can be more reliably removed.

  In the motor control device, if the controller determines that there is an abnormality in the abnormality determination process performed after setting the potential difference between the contacts of the motor relay to a predetermined potential difference, The abnormality determination process can be executed after increasing the potential difference within a range not reaching the predetermined upper limit potential difference.

  As a result, when deposits that cannot be removed with a small arc discharge are adhered, the deposits can be removed while gradually increasing the arc discharge. It becomes possible to make it.

  In the motor control device, the control unit can stop the control of the electric motor when the potential difference between the contacts of the motor relay is equal to or greater than a predetermined upper limit potential difference.

  Thereby, since the magnitude of the current that causes arc discharge can be limited, it is possible to prevent problems such as relay welding and circuit breakdown caused by excessive increase in current.

  In the motor control device, the control unit sets the potential difference between the contacts of the motor relay by setting the duty ratio of the drive signal for outputting the current flowing in each phase of the electric motor to a different value. be able to.

  Thus, by adjusting the duty ratio of each drive signal, the potential difference between the contact points of the relay can be adjusted to a potential difference at which arc discharge can occur.

  An electric power steering apparatus according to the present invention includes a steering shaft, an electric motor that applies an auxiliary steering torque to the steering shaft, and the motor control device described above.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the motor control apparatus and electric power steering apparatus which can suppress the consumption of a relay as much as possible, without impairing the function of a relay.

Preferred embodiments of a motor control device and an electric power steering device according to the present invention will be described below with reference to the accompanying drawings.
[First embodiment]

  First, a schematic configuration of the electric power steering apparatus according to the first embodiment will be described with reference to FIG.

  As shown in the figure, the electric power steering apparatus includes a steering shaft (not shown) connected to the handle 1, a steering column 2 provided outside the steering shaft, and an electric motor that applies auxiliary steering torque to the steering shaft. 20 and an ECU 30 that controls the electric motor 20.

  A steering shaft disposed inside the steering column 2 is connected to a tire rod 6 of a traveling vehicle via universal joints 4a and 4b, a pinion rack mechanism 5 and the like. A torque sensor 10 that detects the steering torque of the handle 1 is provided on the steering shaft. The electric motor 20 is connected to the steering shaft via the reduction gear 3.

  The ECU 30 that controls the electric motor 20 is supplied with electric power from the battery 14 via the ignition key 11 and the power supply relay 13. The ECU 30 calculates a steering assist command value of the assist command based on the steering torque detected by the torque sensor 10 and the vehicle speed detected by the vehicle speed sensor 12, and the electric motor 20 based on the calculated steering assist command value. To control the current supplied to the.

  With reference to FIG. 2, the structure of the motor control apparatus in this embodiment is demonstrated.

  As shown in the figure, the motor control device includes a control circuit 31 (control unit) that controls the entire system, a motor drive circuit 32 that drives an electric motor according to an instruction from the control circuit 31, and a motor according to an instruction from the control circuit 31. The relay 15 for the electric motor 20 (motor relay) for turning on / off the connection between the drive circuit 32 and the electric motor 20 is provided. The control circuit 31 and the motor drive circuit 32 are circuits included in the ECU 30 shown in FIG.

  The motor drive circuit 32 includes six FETs (Field Effect Transistors) 321 to 326 and functions as a three-phase inverter. Specifically, an A-phase arm that supplies current to the A-phase of the electric motor 20 is configured by the FETs 321 and 324, and a B-phase arm that supplies current to the B-phase of the electric motor 20 is configured by the FETs 322 and 325. 326 constitutes a C-phase arm that supplies current to the C-phase of the electric motor 20. The motor drive circuit 32 supplies current to the electric motor 20 in accordance with the gate signal output from the control circuit 31.

  The control circuit 31 controls the entire system by inputting / outputting control signals to / from various devices and circuits. Below, control related to the present invention will be described among various controls performed by the control circuit 31.

  The control circuit 31 executes an abnormality determination process for the relay 15 before starting control of the electric motor 20. This abnormality determination process is a process for determining whether or not there is an abnormality in the relay 15 by turning on the relay 15. Whether there is an abnormality in the relay 15 can be determined, for example, based on whether an open abnormality is detected. More specifically, the value of the current flowing through the relay 15 that is turned on is detected, and when the detected value is smaller than a predetermined lower limit value, it is determined that there is an open abnormality, and it is determined that the relay 15 is abnormal. To do. The control circuit 31 counts the number of times that the abnormality determination process has been executed as the number of determination process executions.

  The control circuit 31 starts control of the electric motor 20 when it is determined in the abnormality determination process that there is no abnormality in the relay 15. That is, when there is no abnormality in the relay 15, the control of the electric motor is started without performing the abnormality determination process again. Therefore, useless relay ON / OFF can be omitted and relay consumption can be suppressed. In addition, it is possible to prevent a dust or oxide deposit that has been removed from adhering to the relay again.

  When the control circuit 31 determines that the relay 15 is abnormal in the abnormality determination process, the control circuit 31 determines whether or not the number of determination process executions has reached a predetermined upper limit number.

  If the number of determination process executions has not reached the predetermined upper limit number, the control circuit 31 turns off the relay 15 and then executes the abnormality determination process. When the determination processing execution count has reached the predetermined upper limit count, the control circuit 31 repeats the ON / OFF of the relay 15 for a predetermined time and then executes the abnormality determination processing. This is because if the abnormality determination process does not become normal even after being repeated a predetermined upper limit number of times, it is considered that a large amount of dust or the like has adhered to the relay contacts, and therefore the relay 15 is repeatedly turned on / off for a predetermined time. This is done to remove large dust and the like.

  The control circuit 31 performs the abnormality determination process after repeating ON / OFF of the relay 15 for a predetermined time, but the condition for repeating ON / OFF is not limited to this. For example, the abnormality determination process may be executed after the relay 15 is turned on / off a predetermined number of times.

  The control circuit 31 stops the control of the electric motor 20 and determines the motor control device when it is determined that the relay 15 is abnormal in the abnormality determination process executed after the relay 15 is turned on / off for a predetermined time. The driver is informed that an abnormality has occurred by turning on a warning lamp. As a result, when dust or the like that cannot be removed even if ON / OFF is repeated for a predetermined time adheres to the relay contact, the control of the electric motor 20 is stopped and the driver is informed to that effect. Can do.

  Next, the operation of the motor control device in the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart illustrating a processing procedure for a pre-system startup check performed in the motor control device.

  First, when the ignition key 11 is rotated to the start position and the engine is started, a check before starting the system of the motor control device is started (step S101).

  Subsequently, the control circuit 31 sets “1” as an initial value in a counter for counting the number of determinations (step S102).

  Subsequently, the control circuit 31 executes an abnormality determination process. That is, the relay 15 for the electric motor is turned on (step S103), an open abnormality is detected (step S104), and it is determined whether or not there is an abnormality in the relay 15 (step S105). If it is determined in this determination that there is no abnormality in the relay 15 (step S105; NO), the control circuit 31 activates the system of the motor control device (step S106). Thereby, the control of the electric motor 20 by the motor control device is started.

  On the other hand, if it is determined in step S105 that the relay 15 is abnormal (step S105; YES), the control circuit 31 determines whether the determination count counted by the counter is equal to or greater than a predetermined upper limit count. Is determined (step S107). If it is determined in this determination that the number of determinations is less than the predetermined upper limit number (step S107; NO), the control circuit 31 turns off the relay 15 (step S108) and counts up the counter for the determination number. Then, 1 is added to the number of determinations (step S109). Then, the process proceeds to step S103 described above.

  On the other hand, when it is determined in step S107 that the number of determinations is equal to or greater than the predetermined upper limit number (step S107; YES), the control circuit 31 repeatedly turns on / off the relay 15 for a predetermined time (step S107). S110). Subsequently, the control circuit 31 executes the abnormality determination process again. That is, the relay 15 is turned on (step S111), an open abnormality is detected (step S112), and it is determined whether there is an abnormality in the relay 15 (step S113). When it is determined that there is no abnormality in the relay 15 by this determination (step S113; NO), the control circuit 31 activates the system of the motor control device (step S106). Thereby, the control of the electric motor 20 by the motor control device is started.

  On the other hand, if it is determined in step S113 that the relay 15 is abnormal (step S113; YES), the control circuit 31 stops the system of the motor control device (step S114), and causes the motor control device to Inform the driver that an abnormality has occurred by turning on a warning lamp.

  As described above, according to the motor control device in the first embodiment, it is possible to determine whether or not there is an abnormality in the motor relay before starting control of the electric motor 20. When there is an abnormality, dust or the like attached to the relay contact can be removed by the on / off operation of the relay 15, and when there is no abnormality, the control of the electric motor 20 can be started. Therefore, the consumption of the relay 15 can be suppressed as much as possible without impairing the function of the relay 15.

  In addition, the number of executions of the abnormality determination process can be limited, and even when dust or the like cannot be removed only by the on / off operation during the abnormality determination process, the relay 15 is turned on / off repeatedly for a predetermined time. Since the abnormality determination process can be executed, dust and the like can be more reliably removed.

In the first embodiment described above, whether or not the number of determination process executions has reached a predetermined upper limit number is adopted as a determination condition when repeatedly executing the abnormality determination process. It is not limited. For example, the time elapsed since the start of the first abnormality determination process is measured as the elapsed time, and whether or not this elapsed time has reached a predetermined upper limit time is adopted as the determination condition. Also good.
[Second Embodiment]

  A second embodiment of the present invention will be described. The motor control device according to the second embodiment is characterized in that when it is determined that there is an abnormality in the relay, arc discharge is generated by the relay, and dust or the like attached to the relay contact is more reliably removed.

  Since the configurations of the motor control device and the electric power steering device in the second embodiment are the same as the configurations of the motor control device and the electric power steering device in the first embodiment, description of each component will be omitted. In the following, differences from the first embodiment will be mainly described.

  The motor control device in the first embodiment described above stops the control of the electric motor 20 when it is determined that there is an abnormality in the abnormality determination process that is executed after the relay 15 is turned on / off for a predetermined time. On the other hand, the motor control device according to the second embodiment differs in that the following processing is performed when it is determined that there is an abnormality in the abnormality determination processing that is executed after the relay 15 is turned on / off for a predetermined time. .

  The control circuit 31 sets the potential difference between the contacts of the relay 15 to a predetermined potential difference when it is determined that there is an abnormality in the relay 15 in the abnormality determination process executed after the relay 15 is turned on / off for a predetermined time. Then, the abnormality determination process is executed. Here, the predetermined potential difference is a potential difference at which arc discharge can occur in the relay 15 and is set to a potential difference at which no inrush current flows. This is because if the current that generates arc discharge is greater than the inrush current, problems such as relay welding and circuit breakdown may occur. By setting such a predetermined potential difference, it is possible to generate arc discharge and prevent problems such as relay welding and circuit breakdown caused by excessively large current that generates arc discharge. it can.

  The control circuit 31 sets the duty ratio of the drive signal output to the arm of each phase of the motor drive circuit 32 to a different value in order to set the potential difference between the relay 15 contacts to a predetermined potential difference. Specifically, for example, the duty ratio of the drive signal to the A phase arm is set to 60%, the duty ratio of the drive signal to the B phase arm is set to 40%, and the duty ratio of the drive signal to the C phase arm is set to 0%. To. Thereby, the voltage of the contact of the relay 15 on the motor drive circuit 32 side can be made higher than the voltage of the contact of the relay 15 on the electric motor 20 side, and a potential difference that can cause arc discharge between the contacts of the relay 15 is increased. Can be generated.

  When the control circuit 31 determines that there is an abnormality in the abnormality determination process executed after setting the potential difference between the contacts of the relay 15 to a predetermined potential difference, the control circuit 31 stops the control of the electric motor 20 and Inform the driver that an abnormality has occurred by turning on a warning lamp. As a result, when dust or the like that cannot be removed by using arc discharge is attached, the control of the electric motor 20 is stopped, and the driver can be informed to that effect.

  Next, the operation of the motor control device in the second embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a processing procedure for a pre-system startup check performed in the motor control device.

  Note that the processes in steps S201 to S213 shown in FIG. 4 are the same as the processes in steps S101 to S113 detailed in the first embodiment (see FIG. 3). Processing in steps S214 to S219 different from the form will be described.

  First, when it is determined in step S213 shown in FIG. 4 that the relay 15 is abnormal (step S213; YES), the control circuit 31 turns off the relay 15 (step S214), and the relay 15 Is set to a predetermined potential difference (step S215).

  Subsequently, the control circuit 31 executes the abnormality determination process again. That is, the relay 15 is turned on (step S216), an open abnormality is detected (step S217), and it is determined whether or not there is an abnormality in the relay 15 (step S218). When it is determined that there is no abnormality in the relay 15 by this determination (step S218; NO), the control circuit 31 activates the system of the motor control device (step S206). Thereby, the control of the electric motor 20 by the motor control device is started.

  On the other hand, when it is determined in step S218 that the relay 15 is abnormal (step S218; YES), the control circuit 31 stops the system of the motor control device (step S219), and the motor control device is abnormal. The driver is informed that a warning has occurred, for example, by turning on a warning lamp.

  In this processing procedure, the control circuit 31 turns off the relay 15 (step S214) and sets the potential difference between the relay 15 contacts to a predetermined potential difference (step S215). It is not limited and the reverse order may be sufficient. That is, the control circuit 31 may set the potential difference between the relay 15 contacts to a predetermined potential difference and then turn off the relay 15.

  As described above, the motor control device according to the second embodiment has the same effects as the motor control device according to the first embodiment described above, and also has the following effects. According to the motor control device in the second embodiment, when dust or the like cannot be removed even if the relay 15 is repeatedly turned on / off for a predetermined time, the dust or the like can be removed using arc discharge. Dust and the like can be reliably removed.

In the motor control device according to the second embodiment described above, the abnormality determination process is repeatedly executed until the determination process execution count reaches the predetermined upper limit count, and the relay 15 is turned on / off for a predetermined time. Although the abnormality determination process is executed, it is not always necessary to perform these processes. That is, when it is determined that there is an abnormality in the relay in the first abnormality determination process, the abnormality determination process may be executed after the relay is turned off and the potential difference between the relay contacts is set to a predetermined potential difference.
[Third embodiment]

  A third embodiment of the present invention will be described. The motor control device according to the third embodiment generates an arc discharge in the relay when it is determined that the relay is abnormal, and gradually increases the arc discharge when the abnormality is still not resolved, thereby providing a relay contact. It is characterized in that adhered dust and the like are more reliably removed.

  Since the configurations of the motor control device and the electric power steering device in the third embodiment are the same as the configurations of the motor control device and the electric power steering device in the first embodiment, description of each component will be omitted. In the following, differences from the first embodiment will be mainly described.

  When the motor control device in the first embodiment described above determines that there is an abnormality in the abnormality determination process executed first, the abnormality determination process is repeatedly executed within a range in which the number of determinations does not reach the upper limit number. On the other hand, the motor control device according to the third embodiment differs in that the following processing is performed when it is determined that there is an abnormality in the abnormality determination processing that is executed first.

  When it is determined that there is an abnormality in the abnormality determination process that is executed first, the control circuit 31 sets the potential difference between the contacts of the relay 15 to a predetermined potential difference and then executes the abnormality determination process. Note that the predetermined potential difference and the method of setting the predetermined potential difference are the same as those in the second embodiment described above, and thus the description thereof is omitted here.

  When the control circuit 31 determines that there is an abnormality in the abnormality determination process performed after setting the potential difference between the contacts of the relay 15 to a predetermined potential difference, the control circuit 31 sets the potential difference between the contacts of the relay 15 to a predetermined upper limit potential difference. The abnormality determination process is executed after increasing within a range not exceeding. As the predetermined upper limit potential difference, for example, a potential difference in which no inrush current flows is applicable. By setting such an upper-limit potential difference, it is possible to prevent a situation in which the current that generates arc discharge reaches the inrush current, so that problems such as relay welding and circuit breakdown caused by excessive current increase can be prevented. It can be prevented in advance.

  In order to increase the potential difference between the relay 15 contacts, for example, the setting may be changed so that the difference between the duty ratio of the drive signal to the A-phase arm and the duty ratio of the drive signal to the B-phase arm increases. This will be described using a specific example. For example, first, the duty ratio of the drive signal to the A phase arm is set to 55%, the duty ratio of the drive signal to the B phase arm is set to 45%, and the duty ratio of the drive signal to the C phase arm is set to 0%. The duty ratio of the drive signal to the A phase arm is changed to 60%, the duty ratio of the drive signal to the B phase arm is changed to 40%, and the duty ratio of the drive signal to the C phase arm is changed to 0%. %. As a result, the voltage at the contact on the motor drive circuit 32 side of the relay 15 increases and the voltage on the contact on the electric motor 20 side of the relay 15 decreases, so that the potential difference between the relay 15 contacts can be widened, and arc discharge is prevented. Can be increased.

  When the potential difference between the contacts of the relay 15 exceeds a predetermined upper limit potential difference, the control circuit 31 stops the control of the electric motor 20 and lights up a warning lamp that an abnormality has occurred in the motor control device. Let the driver know. As a result, when dust or the like that cannot be removed by using arc discharge is attached, the control of the electric motor 20 is stopped, and the driver can be informed to that effect.

  Next, the operation of the motor control device in the third embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a processing procedure for a pre-system startup check performed in the motor control device.

  First, when the ignition key 11 is rotated to the start position and the engine is started, a check before starting the system of the motor control device is started (step S301).

  Subsequently, the control circuit 31 executes an abnormality determination process. That is, the relay 15 for the electric motor is turned on (step S302), an open abnormality is detected (step S303), and it is determined whether or not there is an abnormality in the relay 15 (step S304). When it is determined that there is no abnormality in the relay 15 by this determination (step S304; NO), the control circuit 31 activates the system of the motor control device (step S305). Thereby, the control of the electric motor 20 by the motor control device is started.

  On the other hand, when it is determined in step S304 that the relay 15 is abnormal (step S304; YES), the control circuit 31 determines whether or not the potential difference between the contacts of the relay 15 is equal to or greater than a predetermined upper limit potential difference. Is determined (step S306). In this determination, when the potential difference between the contacts of the relay 15 is equal to or greater than the predetermined upper limit potential difference (step S306; YES), the control circuit 31 stops the system of the motor control device (step S309), causing the motor control device to malfunction. The driver is informed that a warning has occurred, for example, by turning on a warning lamp.

  On the other hand, when it is determined in step S306 that the potential difference between the contacts of the relay 15 is less than the predetermined upper limit potential difference (step S306; NO), the control circuit 31 turns off the relay 15 (step S307). ) Increase the potential difference between the contacts of the relay 15 within a range not exceeding the predetermined upper limit potential difference (step S308). Then, the process proceeds to step S302 described above.

  In this processing procedure, since the control circuit 31 turns off the relay 15 (step S307), the potential difference between the relay 15 contacts is increased within a range not exceeding a predetermined upper limit potential difference (step S308). The order of processing is not limited to this, and may be reversed. That is, the control circuit 31 may increase the potential difference between the contact points of the relay 15 within a range not exceeding the predetermined upper limit potential difference, and then turn off the relay 15.

  As described above, according to the motor control device of the third embodiment, it is possible to determine whether or not there is an abnormality in the motor relay before starting control of the electric motor 20. When there is an abnormality, dust or the like attached to the relay contact can be removed using arc discharge, and when there is no abnormality, the control of the electric motor 20 can be started. Therefore, the consumption of the relay 15 can be suppressed as much as possible without impairing the function of the relay 15.

  In addition, when dust or the like that cannot be removed by a small arc discharge is attached, the dust or the like can be removed while gradually increasing the arc discharge, so that the dust or the like can be reliably removed. Become.

  In the motor control device in the third embodiment described above, when it is determined in the abnormality determination process that the relay is abnormal, the abnormality determination process is executed while gradually increasing the potential difference between the relay contacts. The processing procedure is not limited to this. For example, as in the motor control devices in the first and second embodiments described above, the abnormality determination process is repeatedly executed until the determination process execution number reaches a predetermined upper limit number, or the relay 15 is turned on / off. Even if the abnormality determination process is executed after being repeated for a predetermined time, the abnormality determination process may be executed while the potential difference between the relay contacts is gradually increased.

  Moreover, in each embodiment mentioned above, although the relay 15 for electric motors is provided only in A phase connection, the location which provides a relay is not limited to this. For example, it is good also as providing a relay in the connection of two or more phases among the connection of each phase, such as providing in the connection of A phase and the connection of C phase, respectively. That is, the relay should just be provided in at least one connection among the connection of each phase. And about each relay, what is necessary is just to perform control, such as an abnormality determination process and ON / OFF, according to the process sequence demonstrated in each embodiment mentioned above.

It is a figure showing a schematic structure of an electric power steering device in each embodiment. It is a figure which shows the structure of the motor control apparatus in each embodiment. It is a flowchart for demonstrating the process sequence in the motor control apparatus of 1st Embodiment. It is a flowchart for demonstrating the process sequence in the motor control apparatus of 2nd Embodiment. It is a flowchart for demonstrating the process sequence in the motor control apparatus of 3rd Embodiment.

Explanation of symbols

  2 ... Steering column, 11 ... Ignition key, 13 ... Power relay, 14 ... Battery, 15 ... Electric motor relay, 20 ... Electric motor, 30 ... ECU, 31 ... Control circuit, 32 ... Motor drive circuit, 321-326 ... FET.

Claims (11)

A control unit for controlling the electric motor for the vehicle;
A motor relay for turning on / off the connection between the control unit and the electric motor,
Before the control unit starts control of the electric motor,
An abnormality determination process is performed to determine whether there is an abnormality in the motor relay by turning on the motor relay,
When it is determined that there is no abnormality in the abnormality determination process, the control of the electric motor is started,
When it is determined that there is an abnormality in the abnormality determination process, the abnormality determination process is executed again after turning off the motor relay.   The control unit counts the number of times the abnormality determination process has been performed as the number of determination process executions, and also determines that the abnormality determination process has an abnormality, and the number of determination process executions reaches a predetermined upper limit number. 2. The motor control device according to claim 1, wherein when it has reached, the abnormality determination process is executed after the on / off of the motor relay is repeated for a predetermined time.   The control unit measures a time elapsed since the execution of the abnormality determination process as an elapsed time, and determines that the abnormality determination process has an abnormality, and the elapsed time is a predetermined upper limit. 2. The motor control device according to claim 1, wherein when the time has been reached, the abnormality determination process is executed after repeating ON / OFF of the motor relay for a predetermined time.   The control unit stops the control of the electric motor when it is determined that there is an abnormality in the abnormality determination process executed after the on / off of the motor relay is repeated for a predetermined time. The motor control device according to claim 2.   When the controller determines that there is an abnormality in the abnormality determination process executed after the on / off of the motor relay has been repeated for a predetermined time, the control unit determines the potential difference between the contacts of the motor relay as arc discharge. The motor control device according to claim 2, wherein the abnormality determination process is executed after setting to a predetermined potential difference that may cause a failure.   The control unit stops the control of the electric motor when it is determined that there is an abnormality in the abnormality determination process executed after setting the potential difference between the contacts of the motor relay to the predetermined potential difference. The motor control device according to claim 5, wherein   When it is determined that there is an abnormality in the abnormality determination process, the control unit sets the potential difference between the contacts of the motor relay to a predetermined potential difference that can cause arc discharge, and then executes the abnormality determination process. The motor control device according to claim 1.   When the controller determines that there is an abnormality in the abnormality determination process performed after setting the potential difference between the contacts of the motor relay to the predetermined potential difference, the controller determines the potential difference between the contacts of the motor relay. The motor control device according to claim 7, wherein the abnormality determination process is executed after increasing within a range not reaching a predetermined upper limit potential difference.   The motor control device according to claim 8, wherein the control unit stops the control of the electric motor when a potential difference between the contacts of the motor relay is equal to or greater than a predetermined upper limit potential difference.   The control unit sets the potential difference between the contacts of the motor relay by setting the duty ratio of the drive signal for outputting the current flowing in each phase of the electric motor to a different value. The motor control device according to any one of claims 5 to 9. A steering shaft;
An electric motor for applying auxiliary steering torque to the steering shaft;
The motor control device according to any one of claims 1 to 10,
An electric power steering apparatus comprising:

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