JP6672993B2 - Steering control device - Google Patents

Description

  The present invention relates to a steering control device.

  2. Description of the Related Art Conventionally, as described in Patent Document 1, for example, an electric power steering device for a vehicle (hereinafter, referred to as “EPS”) that generates an assist torque by a motor is known. The EPS control device controls the torque generated by the motor according to the steering torque detected through the torque sensor. The control device energizes the coil of the motor according to the rotation angle of the motor detected through the rotation angle sensor. The control device calculates a steering angle, which is a rotation angle of the steering shaft, based on the rotation angle and the rotation speed of the motor detected through the rotation angle sensor. The steering angle is used for controlling the EPS or for controlling another vehicle-mounted system.

  Here, in the EPS, even when the power switch of the vehicle is turned off and the assist function is stopped, the steering shaft may be rotated by some external force. For this reason, when a configuration in which the steering angle is calculated based on the rotation angle and the rotation speed of the motor is adopted, it is necessary to monitor the rotation state of the motor even while the power switch is turned off. However, in this case, from the viewpoint of suppressing the consumption of the battery mounted on the vehicle, it is required to reduce the power consumption while the power switch is turned off.

  Therefore, the control device of Patent Document 1 detects the number of rotations of the motor by intermittently operating the rotation angle sensor while the power switch is turned off. Further, the control device switches the intermittent cycle according to the rotation state of the motor. The control device sets the operation cycle of the rotation angle sensor to be shorter as the rotation speed of the motor is higher, and sets the operation cycle of the rotation angle sensor to be longer as the rotation speed of the motor is lower. As a result, power consumption is reduced. When the power switch is turned on, the control device calculates the steering angle in consideration of the rotation speed detected while the power switch is turned off.

Registered Patent No. 5140122

  2. Description of the Related Art In recent years, there has been a tendency for computerization of vehicles to progress more and more. From the viewpoint of further enhancing the safety or convenience of the vehicle, various electronic devices or electronic systems are mounted on the vehicle. The power consumption increases as the number of electronic devices mounted on the vehicle increases, so that the load on the battery also increases. For this reason, it is still an issue to reduce power consumption of an electronic device or the like, or to reduce a load on a battery. Further reduction in power consumption while the power switch is off is required.

  An object of the present invention is to provide a steering control device that can further reduce power consumption during a period in which the vehicle power is off.

  A steering control device capable of achieving the above object controls a motor that is a source of torque applied to a steering mechanism of a vehicle according to a steering state when a vehicle power supply is turned on, and is detected through a sensor. A main processing unit that calculates an absolute steering angle using the relative rotation angle of the motor and the rotation speed of the motor, a rotation detection circuit that detects the rotation speed of the motor through the sensor, and supplies power to the rotation detection circuit. And a sub-operation unit including a control circuit for controlling the operation of these three circuits. The control circuit stops the operation of the abnormality detection circuit when the vehicle power is turned off and intermittently operates the rotation detection circuit, and continuously operates the abnormality detection circuit when the vehicle power is on. It is to let. The main processing unit is configured such that when the vehicle power is turned on, the detection result of the abnormality detection circuit does not indicate an abnormality of the power supply circuit, and the vehicle power is turned off immediately before the vehicle power is turned on. When the rotation of the motor is detected during a certain period, the absolute steering angle is calculated in consideration of the number of rotations of the motor obtained through the rotation detection circuit during the off period.

  According to this configuration, the operation of the abnormality detection circuit that detects abnormality of the power supply circuit is stopped during a period in which the vehicle power supply is turned off, so that only the amount of power required to operate the abnormality detection circuit is reduced. Power consumption can be reduced. In addition, if an abnormality occurs in the power supply circuit while the vehicle power supply is turned off, the state in which the abnormality has occurred is basically assumed to be continued even after the electric vehicle power supply is turned on, and the vehicle It is possible to detect an abnormality in the power supply circuit that occurs during the period when the power is off, even after the vehicle power is turned on. Further, when the vehicle power is on, the required level for saving power consumption is lower than when the vehicle power is off. For this reason, from the viewpoint of saving power consumption during the period when the vehicle power supply is off, it is preferable to operate the abnormality detection circuit when the vehicle power supply is turned on.

  In the steering control device described above, the abnormality detection circuit may be configured to capture electric power supplied from the power supply circuit to the rotation detection circuit, and to detect abnormality of the power supply circuit based on the supplied electric power. In this case, it is preferable that the abnormality detection circuit includes a filter that removes noise included in the fetched power.

  According to this configuration, the abnormality detection circuit can detect the abnormality of the power supply circuit based on the power after the noise has been removed by the filter. Therefore, the detection accuracy or detection reliability of the abnormality detection circuit is further improved. Note that, as described above, when the vehicle power is on, the required level for saving power consumption is lower than when the vehicle power is off. For this reason, it is possible to more appropriately secure the processing time of the filter.

  In the above steering control device, when the vehicle power is turned on, the main arithmetic unit is configured to detect when the detection result of the abnormality detection circuit indicates an abnormality of the power circuit, and immediately before the vehicle power is turned on. Preferably, when the rotation of the motor is detected during a period in which the vehicle power is off, the rotation speed of the motor detected by the rotation detection circuit during the off period is invalidated.

  When the rotation detection circuit operates based on the power of the power supply circuit in which the abnormality is detected, there is a concern about the reliability of the motor rotation speed calculated by the rotation detection circuit. In this regard, according to the above configuration, it is possible to avoid calculation of an erroneous absolute steering angle based on the rotational speed of the motor that may be erroneous.

  In the above-described steering control device, when the abnormality detection circuit that detects the abnormality of the power supply circuit is a first abnormality detection circuit, the sub-operation unit performs the abnormality detection of the rotation detection circuit while the vehicle power is off. It is preferable to have the 2nd abnormality detection circuit which detects this. In this case, when the vehicle power is turned on, the main arithmetic unit determines that none of the detection results of the first abnormality detection circuit and the second abnormality detection circuit indicates abnormality, and When the rotation of the motor is detected during a period in which the vehicle power supply is turned off immediately before the vehicle is turned on, the absolute value is taken into consideration in consideration of the number of rotations of the motor obtained through the rotation detection circuit during the off period. Preferably, the steering angle is calculated.

  According to this configuration, the abnormality of the rotation detection circuit can be detected by the second abnormality detection circuit while the vehicle power is off. When no abnormality is detected in any of the power supply circuit and the rotation detection circuit, and when the rotation of the motor is detected during a period in which the vehicle power is off immediately before the vehicle power is turned on, the motor is turned off. The absolute steering angle is calculated in consideration of the number of rotations of the motor obtained through the rotation detection circuit during a certain period. Therefore, the reliability of the absolute steering angle can be further improved.

  In the above steering control device, when the vehicle power is turned on, at least one of the first abnormality detection circuit and the second abnormality detection circuit indicates an abnormality when the vehicle power is turned on. When the rotation of the motor is detected during a period in which the vehicle power is off immediately before the vehicle power is turned on, the rotation of the motor detected by the rotation detection circuit during the off period Preferably, the number is invalidated.

  Not only when an abnormality is detected in the rotation detection circuit, but also when the rotation detection circuit operates based on the power of the power supply circuit in which the abnormality is detected, the reliability of the rotation speed of the motor calculated by the rotation detection circuit is reduced. I am concerned. In this regard, according to the above configuration, it is possible to avoid calculation of an erroneous absolute steering angle based on the rotational speed of the motor that may be erroneous.

  In the steering control device described above, the main calculation unit calculates a basic component of a target torque to be generated by the motor based on at least a steering torque as a state quantity indicating the steering state, and calculates the basic component based on the absolute steering angle. The compensation control for the component may be executed. In this case, when the vehicle power supply is turned on, the main processing unit may perform the compensation when at least one of the first abnormality detection circuit and the second abnormality detection circuit indicates an abnormality. It is preferable to stop the execution of the control.

  When an abnormality is detected in the power supply circuit or when an abnormality is detected in the rotation detection circuit, the reliability of the rotation speed of the motor calculated by the rotation detection circuit is calculated using the rotation speed of the motor. There is concern about the reliability of the absolute steering angle. In this regard, according to the above-described configuration, the execution of the compensation control using the absolute steering angle, for which reliability is concerned, is avoided, so that the steering control with a higher priority on safety can be executed.

  According to the steering control device of the present invention, it is possible to further reduce the power consumption while the vehicle power is off.

1 is a schematic configuration diagram illustrating an embodiment of an electric power steering device. FIG. 1 is a block diagram of an electronic control device according to one embodiment. FIG. 2 is a block diagram of a backup operation unit according to one embodiment. 9 is a flowchart illustrating a processing procedure of a control circuit in the backup operation unit according to the embodiment. 5 is a flowchart illustrating a processing procedure of motor control according to the embodiment.

Hereinafter, an embodiment in which the steering control device is embodied in an ECU (electronic control device) of an electric power steering device (hereinafter, referred to as “EPS”) will be described.
<Schematic configuration of EPS>
As shown in FIG. 1, the EPS 10 controls a steering mechanism 20 that steers steered wheels based on a driver's steering operation, a steering assist mechanism 30 that assists the driver in steering operation, and an operation of the steering assist mechanism 30. The ECU 40 is provided.

  The steering mechanism 20 includes a steering wheel 21 operated by a driver, and a steering shaft 22 that rotates integrally with the steering wheel 21. The steering shaft 22 includes a column shaft 22a connected to the steering wheel 21, an intermediate shaft 22b connected to a lower end of the column shaft 22a, and a pinion shaft 22c connected to a lower end of the intermediate shaft 22b. The lower end of the pinion shaft 22c is engaged with a rack shaft 23 (more precisely, a portion 23a having rack teeth) extending in a direction intersecting the pinion shaft 22c. Therefore, the rotational movement of the steering shaft 22 is converted into a reciprocating linear movement of the rack shaft 23 by the rack and pinion mechanism 24 including the pinion shaft 22c and the rack shaft 23. The reciprocating linear motion is transmitted to the left and right steered wheels 26, 26 via tie rods 25 connected to both ends of the rack shaft 23, respectively, so that the steered angles θta of the steered wheels 26, 26 are changed. You.

  The steering assist mechanism 30 includes a motor 31 that is a source of a steering assist force (assist force). As the motor 31, for example, a three-phase brushless motor is employed. The motor 31 is connected to the column shaft 22a via a speed reduction mechanism 32. The reduction mechanism 32 reduces the rotation of the motor 31 and transmits the reduced rotation force to the column shaft 22a. That is, the driver's steering operation is assisted by applying the torque of the motor 31 to the steering shaft 22 as a steering assist force.

The ECU 40 acquires detection results of various sensors provided in the vehicle as information (state quantity) indicating a driver's request, a traveling state, and a steering state, and controls the motor 31 according to the acquired various information. . Examples of the various sensors include a vehicle speed sensor 51, a torque sensor 52, and a rotation angle sensor 53. The vehicle speed sensor 51 detects a vehicle speed (running speed of the vehicle) V. The torque sensor 52 is provided on, for example, the column shaft 22a. The torque sensor 52 detects a steering torque τ applied to the steering shaft 22. The rotation angle sensor 53 is provided on the motor 31. Rotation angle sensor 53 generates an electrical signal S _theta corresponding to the rotation angle theta _m of the motor 31.

ECU40 detects a rotation angle theta _m of the motor 31 on the basis of the electric signal S _theta generated by the rotation angle sensor 53, the motor 31 is vector control using the rotation angle theta _m being the detection. Further, the ECU 40 calculates a steering angle θs, which is a rotation angle of the steering wheel 21. The ECU 40 calculates a target assist torque based on the steering torque τ, the vehicle speed V, and the steering angle θs, and supplies the motor 31 with drive power for causing the steering assist mechanism 30 to generate the calculated target assist torque.

<Configuration of ECU>
As shown in FIG. 2, the ECU 40 includes a drive circuit (inverter) 41, a microcomputer 42, a backup operation unit 43, and a power supply detection unit 44.

  Power is supplied to the drive circuit 41, the microcomputer 42, and the backup operation unit 43 from a DC power supply 61 such as a battery mounted on the vehicle. The first power supply line 62 connects the microcomputer 42 and the DC power supply 61 (more precisely, its positive terminal). The first power supply line 62 is provided with a vehicle power switch 63 such as an ignition switch. On the first power supply line 62, a first connection point 64 is set between the power switch 63 and the microcomputer 42. The second connection line 65 is connected between the first connection point 64 and the drive circuit 41. In the first power supply line 62, a second connection point 66 is set between the DC power supply 61 and the power switch 63. The third connection line 67 is connected between the second connection point 66 and the backup operation unit 43. When the power switch 63 is turned on, the power of the DC power supply 61 is supplied to the microcomputer 42 via the first power supply line 62 and to the drive circuit 41 via the second power supply line 65. Further, the power of the DC power supply 61 is supplied to the backup operation unit 43 via the third power supply line 67. Electric power of a DC power supply 61 is supplied to the rotation angle sensor 53 via a power supply line (not shown).

  The drive circuit 41 has two switching elements such as field-effect transistors (FETs) connected in series as an arm as a basic unit, and has three arms corresponding to three phases (U, V, W). This is a PWM inverter connected in parallel. The drive circuit 41 converts DC power supplied from the DC power supply 61 into three-phase AC power based on a control signal generated by the microcomputer 42. The three-phase AC power is supplied to the motor 31 (more precisely, the motor coil of each phase) via a power supply path of each phase (not shown).

The microcomputer 42 calculates a basic component of a target assist torque to be generated by the motor 31 based on the steering torque τ and the vehicle speed V. The microcomputer 42 is configured to computes the rotation angle theta _m of the motor 31 on the basis of the electric signal S _theta generated by the rotation angle sensor 53, calculates the steering angle θs based on the rotation angle theta _m being the calculation. The microcomputer 42 calculates various compensation components based on the calculated steering angle θs as part of compensation control for the basic component of the target assist torque. These compensation components include, for example, a steering return control component for returning the steering wheel 21 to the neutral position. The microcomputer 42 calculates a current command value according to a value obtained by adding a basic component of the target assist torque and various compensation components, and performs a current feedback control for causing an actual current value supplied to the motor 31 to follow the current command value. To generate a control signal for the drive circuit 41. This control signal defines the on-duty of each switching element of the drive circuit 41. The actual current value supplied to the motor 31 is detected via a current sensor (not shown) provided in a power supply path between the drive circuit 41 and the motor 31. When a current corresponding to the control signal is supplied to the motor 31 through the drive circuit 41, the motor 31 generates a torque corresponding to the target assist torque. The torque of the motor 31 is applied to the vehicle steering mechanism (in this example, the column shaft 22a) via the speed reduction mechanism 32 as an assist force to assist the driver in steering.

The backup calculator 43 calculates the number of rotations of the motor 31 and the direction of rotation of the motor 31 based on the electric signal _Sθ generated by the rotation angle sensor 53.
The power detection unit 44 detects whether the power switch 63 is turned on (vehicle power on) or off (vehicle power off). The power detection unit 44 may detect the state of the power switch 63 based on the position of the power switch 63, or may detect the state of the power switch 63 based on the voltage between the power switch 63 and the microcomputer 42 on the first power supply line 62. May be detected. The power detection unit 44 generates an electric signal _SIG indicating whether the power switch 63 is turned on or off.

<Steering angle detection processing>
Next, detection processing of the steering angle θs will be described in detail.
As the rotation angle sensor 53, for example, an MR sensor (a magnetoresistive sensor), which is a type of a magnetic sensor, is employed. The MR sensor generates an electric signal _Sθ corresponding to the magnetic field direction of a bias magnet having a pair of magnetic poles (N pole and S pole) provided at the end of the output shaft of the motor 31. The electric signal S _theta, sine signal (sin signal) which varies sinusoidally with respect to the rotation angle theta _m of the motor 31, and the cosine signal that varies in a cosine wave with respect to the rotation angle theta _m of the motor 31 (cos signal) including. Each of the sine signal and the cosine signal is a signal having a period during which the motor 31 rotates by an angle (here, 360 °) corresponding to one magnetic pole pair of the bias magnet. The microcomputer 42 detects the rotation angle θ _m of the motor 31 by calculating the arc tangent value of the sine signal and the cosine signal.

However, the rotation angle theta _m of the motor 31 which is calculated on the basis of the electric signal S _theta generated (sine and cosine signals) by the rotational angle sensor 53 is a relative angle. On the other hand, for example, the steering angle θs used for the steering return control is an absolute angle. Therefore, the microcomputer 42 calculates the steering angle θs as an absolute value by applying, for example, the rotation angle θ _m (electrical angle) of the motor 31 to the following equation (1).

Steering angle (absolute angle) θs = (θ _m + N La 360 °) / Gr ... (1)
However, "N" is one period of the rotation angle theta _m, that is, the rotational speed of the case where it has been defined as one revolution varying from 0 over an electrical angle of up to 360 ° (the number of cycles). The rotation speed N is obtained through the backup operation unit 43. “Gr” is a gear ratio (reduction ratio) of the reduction mechanism 32 that reduces the rotation of the motor 31. Information indicating the gear ratio Gr is stored in a storage device (not shown) of the microcomputer 42.

<When the power switch is turned off>
Here, the microcomputer 42 when the power switch 63 is turned off, is stored in a storage device (not shown) the rotational speed N acquired through the rotation angle theta _m and the backup operation unit 43 of the motor 31 in the immediately preceding. This is to calculate an accurate steering angle θs when the power switch 63 is turned on again.

However, there is a concern that the steering wheel 21 may be operated for some reason while the power switch 63 is off. In this case, by different rotation angle theta _m and the rotational speed N of the actual rotation angle theta _m and the rotational speed N of the motor 31 stored in the storage device immediately before the supply of electric power to the microcomputer 42 is stopped, the power switch When 63 is turned on again, there is a possibility that an accurate steering angle θs cannot be obtained. Therefore, it is preferable to monitor at least the rotation speed N of the motor 31 even when the power switch 63 is turned off.

  Therefore, in this example, even when the power switch 63 is turned off, the power supply to the rotation angle sensor 53 and the backup operation unit 43 is continued, so that the rotation speed N of the motor 31 is continuously counted. Further, in order to ensure the detection reliability of the rotation speed N, the backup operation unit 43 is also required to have its own abnormality detection function (self-diagnosis function). This is because while the power switch 63 is off, the power supply to the microcomputer 42 is cut off in order to suppress the consumption of the DC power supply 61. The specific configuration of the backup operation unit 43 is as follows.

<Backup operation part>
As shown in FIG. 3, the backup operation unit 43 has a power supply circuit 71, a rotation detection circuit 72, a first abnormality detection circuit 73, a second abnormality detection circuit 74, and a control circuit 75.

  The power supply circuit 71 converts power supplied from the DC power supply 61 into power suitable for the operation of the rotation detection circuit 72 and other electric circuits (not shown). Incidentally, the other electric circuits include those that operate when the power switch 63 is turned on. The power supply circuit 71 is a constant voltage source that keeps its output voltage constant.

The rotation detection circuit 72 operates by consuming the electric power generated by the power supply circuit 71. The rotation detection circuit 72 captures a sine signal and a cosine signal as the electric signal _Sθ generated by the rotation angle sensor 53 at a predetermined sampling cycle, and based on the captured sine signal and cosine signal, the rotation speed N of the motor 31. And the rotation direction D of the motor 31 are calculated. The rotation detection circuit 72 generates a rotation detection signal _Sr0 including the rotation speed N and the rotation direction D of the motor 31. Incidentally, the rotation detection circuit 72 is a digital circuit, and the rotation detection signal _Sr0 generated by the rotation detection circuit 72 is a digital signal.

The rotation detection circuit 72 detects the rotation direction D of the motor 31 as follows. That is, the rotation detection circuit 72 plots the coordinates (cos θ _m , sin θ _m ), which are a set of values of the sine signal and the cosine signal, in the rectangular coordinate system of cos θ _m and sin θ _m, and the plotted coordinates are located. The rotation direction D of the motor 31 is detected based on the change of the quadrant. Incidentally, the rotation detection circuit 72 determines the quadrant where the plotted coordinates are located, based on the sign of the values of sin θ _m and cos θ _m . When the coordinates change from the first quadrant to the second quadrant, for example, the rotation detection circuit 72 determines that the rotation direction D of the motor 31 is the forward direction. In addition, when the coordinates change from the first quadrant to the fourth quadrant, for example, the rotation detection circuit 72 determines that the rotation direction D of the motor 31 is the reverse direction.

The rotation detection circuit 72 detects the rotation speed N of the motor 31 as follows. That is, the rotation detection circuit 72 has a counter. The rotation detecting circuit 72 increments the count value by a constant value (eg, a positive natural number such as 1 or 2) each time the quadrant where the coordinates (cos θ _m , sin θ _m ), which is a set of sine signal and cosine signal values, is switched. Increase or decrease. When the rotation direction D of the motor 31 is the forward direction, the rotation detection circuit 72 increments the count value by a constant value each time the coordinates change by one quadrant. When the rotation direction D of the motor 31 is the reverse direction, the rotation detection circuit 72 decreases the count value by a fixed value each time the coordinates change by one quadrant. The rotation detection circuit 72 detects the rotation speed N of the motor 31 based on the count value.

The first abnormality detection circuit 73 detects an abnormality of the power supply circuit 71. The first abnormality detection circuit 73 captures, for example, the output voltage of the power supply circuit 71 and detects an abnormality in the output voltage by comparing the captured output voltage with a threshold. The first abnormality detection circuit 73 generates a first abnormality detection signal _Sr1 indicating whether the power supply circuit 71 is normal or abnormal as a detection result of the abnormality of the power supply circuit 71. Further, the first abnormality detection circuit 73 has a filter 73a. The filter 73a removes noise superimposed on the output voltage of the power supply circuit 71.

The second abnormality detection circuit 74 detects an abnormality of the rotation detection circuit 72. The second abnormality detection circuit 74 captures the rotation detection signal _Sr0 generated by the rotation detection circuit 72, and performs rotation based on the rotation speed N and the rotation direction D of the motor 31 included in the captured rotation detection signal _Sr0. An abnormality of the detection circuit 72 is detected. The second abnormality detection circuit 74 generates a second abnormality detection signal _Sr2 indicating whether the rotation detection circuit 72 is normal or abnormal as a detection result of the abnormality of the rotation detection circuit 72.

The second abnormality detection circuit 74 detects the rotation by utilizing the fact that, for example, when the motor 31 is rotating normally, the coordinates (cos θ _m , sin θ _m ) plotted in the rectangular coordinate system transition by one quadrant. An abnormality of the circuit 72 is detected. That is, it is impossible for the coordinates to suddenly transition to the next quadrant (quadrants located diagonally to each other in the orthogonal coordinate system). For example, when the motor 31 rotates forward, the coordinates located in the first quadrant do not skip the second quadrant and transition to the third quadrant. Therefore, when the coordinates transition to the next quadrant, this can be detected as abnormal.

The control circuit 75 captures the electric signal _SIG generated by the power detection unit 44 and determines whether the power switch 63 is on or off based on the captured electric signal _SIG . The control circuit 75 controls the operations of the power supply circuit 71, the rotation detection circuit 72, the first abnormality detection circuit 73, and the second abnormality detection circuit 74 according to the state of the power switch 63. Specifically, according to the state of the power switch 63, the control circuit 75 operates in response to an operation control signal S1 for the power supply circuit 71, an operation control signal S2 for the rotation detection circuit 72, and an operation control signal S4 for the first abnormality detection circuit 73. , And an operation control signal S3 for the second abnormality detection circuit 74. The operation control signal S1 is a command signal for operating and stopping the power supply circuit 71. The operation control signals S2 and S3 are command signals for intermittently operating the rotation detection circuit 72 and the second abnormality detection circuit 74, respectively. The operation control signal S4 is a command signal for continuously operating the first abnormality detection circuit 73 or stopping the operation. The control circuit 75 supplies operating power to the first abnormality detection circuit 73 and the second abnormality detection circuit 74, respectively.

<Process of control circuit>
Next, a processing procedure of the control circuit 75 will be described.
As shown in the flowchart of FIG. 4, the control circuit 75 determines whether the power switch 63 is turned off based on the electric signal _SIG generated by the power detection unit 44 (Step S101).

  When it is determined that the power switch 63 is off (YES in step S101), the control circuit 75 stops the operation of the first abnormality detection circuit 73, while the power circuit 71, the rotation detection circuit 72, and the second Are operated intermittently (step S102).

  Specifically, the control circuit 75 generates an operation control signal S4 for instructing the first abnormality detection circuit 73 to stop the operation. At this time, the control circuit 75 may stop supplying power to the first abnormality detection circuit 73. Further, the control circuit 75 generates operation control signals S1, S2, S3 for instructing the power supply circuit 71, the rotation detection circuit 72, and the second abnormality detection circuit 74 to operate intermittently. The power switch 63 is turned off by stopping the operation of the first abnormality detection circuit 73 in addition to intermittently operating the power supply circuit 71, the rotation detection circuit 72, and the second abnormality detection circuit 74. The power consumption during this period is more suitably suppressed.

  When it is determined that the power switch 63 is not turned off (NO in step S101), the control circuit 75 determines that the power switch 63 is on, and continuously operates the power circuit 71 and the first abnormality detection circuit 73. Make it work. Further, the control circuit 75 causes the rotation detection circuit 72 and the second abnormality detection circuit 74 to operate intermittently (step S103).

  Specifically, the control circuit 75 generates operation control signals S1 and S4 for instructing the power supply circuit 71 and the first abnormality detection circuit 73 to operate continuously. Further, the control circuit 75 generates operation control signals S2 and S3 for instructing the rotation detection circuit 72 and the second abnormality detection circuit 74 to operate intermittently. When the power switch 63 is turned on, the power circuit 71 is operated continuously (always operating) because the electric power generated by the power circuit 71 is used in other electric circuits other than the rotation detection circuit 72. It is.

  As described above, in the backup operation unit 43, after the power switch 63 is turned on, the first abnormality detection circuit 73 is operated to detect the abnormality of the power supply circuit 71. Is determined based on the following two viewpoints (A) and (B).

  (A) If an abnormality occurs in the power supply circuit 71 while the power switch 63 is turned off, the state in which the abnormality has occurred basically continues even after the power switch 63 is turned on.

  (B) When the power switch 63 is on, the required level for reducing power consumption is lower than when the power switch 63 is off. This is because, for example, in the case of a gasoline vehicle, when the engine is operating, the electric power generated by the alternator is charged in the DC power supply 61.

<Motor control processing procedure>
Next, a processing procedure of control of the motor 31 executed by the microcomputer 42 will be described. The power switch 63 is off.

As shown in the flowchart of FIG. 5, when the power switch 63 is turned on (step S201), the microcomputer 42 outputs the first abnormality detection result obtained by the first abnormality detection circuit 73 and the second abnormality detection circuit 74. The abnormality detection signal _Sr1 and the second abnormality detection signal _Sr2 are captured (Step S202).

Next, the microcomputer 42 determines whether the power supply circuit 71 is abnormal based on the second abnormality detection signal _Sr2 (step S203).
When it is determined that the power supply circuit 71 is not abnormal (NO in step S203), the microcomputer 42 determines whether the rotation detection circuit 72 is abnormal based on the first abnormality detection signal _Sr1 (step S204). .

  When it is determined that the rotation detection circuit 72 is not abnormal, the microcomputer 42 calculates the steering angle θs as an absolute value in consideration of the rotation speed N of the motor 31 during the period when the power switch 63 is off (step S1). S205).

Knowing the number of revolutions N (count value) between the power switch 63 is turned off, the last power switch 63 is found to the rotation angle theta _m of between being turned off until the power switch 63 current is turned on. When the power switch 63 is turned on again, the microcomputer 42 sets the rotation angle θ _m (relative angle) stored when the power switch 63 was last turned off to the rotation angle (while the power switch 63 is turned off). by adding the change angle), to detect the current rotation angle theta _m. The microcomputer 42 calculates the steering angle by using the current rotational angle theta _m (absolute angle).

  However, the reason why the rotation speed N of the motor 31 during the period when the power switch 63 is off is taken into consideration is that the rotation of the motor 31 is detected during the period when the power switch 63 is off immediately before the power switch 63 is turned on. Only when it is done. This is because when the rotation of the motor 31 is not detected while the power switch 63 is off, the rotation speed N to be taken into account is not detected.

The microcomputer 42 controls the power supply to the motor 31 with the current rotation angle theta _m of the motor 31 (step S206). Further, the microcomputer 42 executes compensation control such as steering return control using the steering angle θs.

  When the microcomputer 42 determines that the rotation detection circuit 72 is abnormal (YES in step S204), and when determines that the power supply circuit 71 is abnormal (YES in step S203), the microcomputer 42 turns on the power switch 63. Is invalidated during the period in which is turned off (step S207).

  This is not only when an abnormality is detected in the rotation detection circuit 72, but also when the rotation detection circuit 72 operates based on the power of the power supply circuit 71 in which the abnormality is detected. This is because reliability with respect to the rotation speed N of 31 is concerned. Therefore, the microcomputer 42 does not use the rotation speed N detected by the rotation detection circuit 72 until it is determined that the rotation detection circuit 72 is not abnormal. Accordingly, it is possible to avoid calculation of an erroneous steering angle (absolute angle) θs based on the rotational speed N of the motor 31 which may be erroneous.

  However, the number of revolutions N of the motor 31 during the period when the power switch 63 is off is invalidated because the rotation of the motor 31 is stopped during the period when the power switch 63 is off immediately before the power switch 63 is turned on. Only when detected. This is because when the rotation of the motor 31 is not detected while the power switch 63 is turned off, the rotation speed N to be invalidated is not detected.

The microcomputer 42 does not considering the rotational speed N of the period the power switch 63 has been turned off, by using the rotation angle theta _m of the motor 31 to be detected through the rotational angle sensor 53 to control the power supply to the motor 31 (Step S206). Further, the microcomputer 42 stops executing the compensation control based on the steering angle θs such as the steering return control. This is because it is not possible to calculate the correct steering angle (absolute angle) θs unless the correct rotation speed N is known, and thus it is not possible to execute appropriate compensation control. By avoiding the execution of the compensation control using the steering angle θs for which reliability is concerned, it is possible to execute the steering control giving higher priority to safety.

<Effects of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) While the power switch 63 of the vehicle is off, the operation of the first abnormality detection circuit 73 is stopped. Therefore, while the power switch 63 is off, the power consumption can be reduced by the amount of power required to operate the first abnormality detection circuit 73. Note that it is difficult to stop the operation of the second abnormality detection circuit 74 while the power switch 63 is off. This is because it is necessary to detect an abnormality of the rotation detection circuit 72 that operates while the power switch 63 is off.

  (2) Further, the abnormality of the power supply circuit 71 (such as an abnormality in the output voltage) that occurs during the period in which the power switch 63 is off basically continues after the power switch 63 is turned on. For this reason, it is possible to detect an abnormality of the power supply circuit 71 that occurs during a period in which the power switch 63 is off, even after the power switch 63 is turned on. Further, when the power switch 63 is turned on, the required level for saving current consumption is lower than when the power switch 63 is turned off. Therefore, from the viewpoint of further saving power consumption during the period when the power switch 63 is off, it is preferable to operate the first abnormality detection circuit 73 when the power switch 63 is turned on.

  (3) Further, by adopting a configuration in which the first abnormality detection circuit 73 is operated when the power switch 63 of the vehicle is turned on, the filter 73a can be provided in the first abnormality detection circuit 73. . This is because, when the power switch 63 is turned on, the required level for saving power consumption is lower than when the power switch 63 is turned off, and the processing time of the filter 73a is more appropriately secured. Is possible.

  The shorter the processing time of the filter 73a, the lower the power consumption of the filter 73a. However, in this case, there is a concern that noise is not sufficiently removed. On the other hand, if the processing time of the filter 73a is more appropriately secured, noise is more appropriately removed, but as the processing time of the filter 73a becomes longer, the power consumption of the filter 73a increases. In this regard, if the power switch 63 is turned on, more appropriate processing time of the filter 73a can be secured. In this case, the first abnormality detection circuit 73 can detect an abnormality of the power supply circuit 71 based on the output voltage after noise has been more appropriately removed by the filter 73a. Therefore, it is possible to prevent the first abnormality detection circuit 73 from erroneously detecting an abnormality in the power supply circuit 71. That is, the detection accuracy or detection reliability for the abnormality of the power supply circuit 71 by the first abnormality detection circuit 73 is further improved.

  By the way, in the case where the configuration in which the first abnormality detection circuit 73 is operated even during the period when the power switch 63 is off is adopted, from the viewpoint of further saving power consumption during the period when the power switch 63 is off, In some cases, it may be difficult to provide the filter 73a in the abnormality detection circuit 73. This is because providing a filter leads to an increase in power consumption. In the case where the first abnormality detection circuit 73 is configured to operate intermittently while the power switch 63 is turned off, the operation cycle of the first abnormality detection circuit 73 (the period during which the operation power is supplied) is It takes about several tens μs (for example, 40 μs). For this reason, it is difficult to employ a filter that can accurately remove noise within the operation cycle of the first abnormality detection circuit 73.

  Whether a filter is provided in the second abnormality detection circuit 74 depends on whether the rotation detection circuit 72 is a digital circuit that generates a digital signal or an analog circuit that generates an analog signal. When the rotation detection circuit 72 is a digital circuit, the second abnormality detection circuit 74 may not be provided with a filter. This presupposes that a digital signal is less susceptible to noise than an analog signal, and that noise countermeasures are taken in an analog circuit portion before generating a digital signal.

<Other embodiments>
The present embodiment may be implemented with the following modifications.
When the control circuit 75 determines that the power switch 63 is off (YES in step S101 in the flowchart of FIG. 4), the control circuit 75 may operate the power circuit 71 continuously. That is, the control circuit 75 may always operate the power supply circuit 71 regardless of the state of the power switch 63.

When the power switch 63 is turned on and the electric power generated by the power supply circuit 71 is not used in another electric circuit other than the rotation detection circuit 72, the control circuit 75 uses the power supply circuit 71 by the first abnormality detection circuit 73. The operation of the power supply circuit 71 may be stopped after the abnormality of the power supply circuit 71 is detected. Specifically, when the control circuit 75 detects that the power switch 63 has been turned on based on the electric signal _SIG generated by the power detection unit 44, the control circuit 75 generates the first abnormality generated by the first abnormality detection circuit 73. Of the abnormality detection signal _Sr1 . When the received first abnormality detection signal _Sr1 indicates an abnormality of the power supply circuit 71, the control circuit 75 instructs the first abnormality detection circuit 73 to stop the operation. A signal S4 is generated.

  When it is determined that the power switch 63 is not turned off (NO in step S101 in the flowchart of FIG. 4), the control circuit 75 stops the operations of the rotation detection circuit 72 and the second abnormality detection circuit 74, respectively. It may be. This is for the following reason. That is, when the power switch 63 is switched from off to on, in order for the microcomputer 42 to calculate a more accurate steering angle θs, it is only necessary to detect the rotation of the motor 31 during the period when the power switch 63 is off. . Therefore, when the power switch 63 is turned on, the operation of the rotation detection circuit 72 may be stopped. When the rotation detection circuit 72 is stopped, it is not necessary to detect the abnormality. Therefore, when the operation of the rotation detection circuit 72 is stopped, the operation of the second abnormality detection circuit 74 may be stopped.

  -As the 1st abnormality detection circuit 73, you may employ | adopt the structure which omitted the filter 73a. Even in this case, the first abnormality detection circuit 73 can detect an abnormality of the power supply circuit 71.

  A configuration in which the second abnormality detection circuit 74 is omitted as the backup operation unit 43 may be employed. This makes it impossible to detect the abnormality of the rotation detection circuit 72, but the amount of power required to operate the second abnormality detection circuit 74 during the period when the power switch 63 is turned off. Only power consumption can be reduced. When the configuration in which the second abnormality detection circuit 74 is omitted is adopted, the determination processing in step S204 in the flowchart of FIG. 5 is also omitted. That is, when it is determined that the power supply circuit 71 is not abnormal (NO in step S203), the process proceeds to step S205.

  The steering angle θs calculated by the microcomputer 42 may be used not only in the EPS 10 but also in a control device of another vehicle-mounted system. Other on-vehicle systems include, for example, a vehicle stability control system or various driving support systems.

  In this example, the microcomputer 42 executes the compensation control based on the steering angle θs. However, a configuration in which the compensation control is not executed based on the steering angle θs may be adopted depending on the product specifications. However, in this case, the ECU 40 or the microcomputer 42 may have a function of calculating the steering angle θs. The steering angle θs may not be used in the EPS 10 but may be used in another vehicle-mounted system.

  In this example, the steering control device is embodied in the ECU 40 of the EPS 10, but may be embodied in a steer-by-wire (SBW) type steering device control device having a clutch function. Some SBW steering devices have the following configuration on the assumption that the steering wheel and the steered wheels are mechanically separated. That is, the steering device includes a clutch that interrupts a power transmission path between the steering wheel and the steered wheels, a reaction force motor that is a source of a steering reaction force applied to the steering shaft, and a steering wheel that steers the steered wheels. It has a steering motor that is a source of steering force.

  When the vehicle is running, the control device of the steering device releases the clutch to maintain a state in which the steering wheel and the steered wheels are mechanically separated. Further, the control device calculates a target steering angle of the steered wheels using the steering angle calculated based on the rotation angle of the reaction motor and the rotation angle of the steering motor. The control device controls the power supply to the turning motor so that the actual turning angle detected based on the rotation angle of the turning motor matches the target turning angle. When an abnormality occurs in the reaction motor or the like or when the power of the vehicle is turned off, the control device connects the clutch based on a viewpoint of fail-safe or the like.

  Here, even when the power of the vehicle is turned off, there is a concern that the steering shaft is rotated by some external force. In this case, since the rotation angle of the reaction force motor immediately before the power supply of the vehicle is turned off is different from the actual rotation angle, there is a possibility that an accurate steering angle cannot be obtained when the power supply of the vehicle is turned on again. Therefore, similarly to the EPS 10, in the SBW-type steering device, it is preferable to monitor the rotation of the reaction motor when the power of the vehicle is turned off. In addition, it is the same as the EPS 10 that the power consumption is required to be reduced while the power is off. Therefore, it is preferable that the control device of the SBW type steering device also has the same functions (the rotation speed monitoring function and the power saving function) as those of the backup operation unit 43 of the present example.

  Reference Signs List 20: steering mechanism, 31: motor, 40: ECU (steering control device), 42: microcomputer (main calculation unit), 43: backup calculation unit (sub calculation unit), 53: rotation angle sensor (sensor), 72: Rotation detection circuit, 71: power supply circuit, 73: first abnormality detection circuit (abnormality detection circuit), 73a: filter, 74: second abnormality detection circuit, 75: control circuit.

Claims (6)

When the vehicle power is turned on, the motor that is the source of the torque applied to the steering mechanism of the vehicle is controlled in accordance with the steering state, and the relative rotation angle of the motor and the rotation of the motor detected through a sensor. A main calculation unit that calculates the absolute steering angle using the number,
A rotation detection circuit that detects the number of rotations of the motor through the sensor, a power supply circuit that supplies power to the rotation detection circuit, an abnormality detection circuit that detects an abnormality in the power supply circuit, and control that controls operations of these three circuits A sub-operation unit including a circuit,
The control circuit stops the operation of the abnormality detection circuit when the vehicle power is turned off and intermittently operates the rotation detection circuit, and continuously operates the abnormality detection circuit when the vehicle power is on. And intermittently operate or stop the rotation detection circuit,
The main processing unit is configured such that when the vehicle power is turned on, the detection result of the abnormality detection circuit does not indicate an abnormality of the power circuit, and the vehicle power is turned off immediately before the vehicle power is turned on. A steering control device that calculates the absolute steering angle by taking into account the number of rotations of the motor obtained through the rotation detection circuit during the off period when the rotation of the motor is detected during the off period. The steering control device according to claim 1,
The abnormality detection circuit captures power supplied from the power supply circuit to the rotation detection circuit, and detects an abnormality of the power supply circuit based on the captured power.
The steering control device, wherein the abnormality detection circuit includes a filter that removes noise included in the fetched electric power. In the steering control device according to claim 1 or 2,
When the vehicle power is turned on, when the detection result of the abnormality detection circuit indicates an abnormality of the power circuit, and when the vehicle power is turned off immediately before the vehicle power is turned on, A steering control device that, when rotation of the motor is detected during a certain period, invalidates the rotation speed of the motor detected by the rotation detection circuit during the off period. In the steering control device according to claim 1 or 2,
When the abnormality detection circuit that detects the abnormality of the power supply circuit is a first abnormality detection circuit, the sub-operation unit detects a second abnormality that detects an abnormality of the rotation detection circuit while the vehicle power supply is off. Having a detection circuit,
When the vehicle power is turned on, the main processing unit does not show any abnormality in the detection results of the first abnormality detection circuit and the second abnormality detection circuit, and the vehicle power is turned on. When the rotation of the motor is detected during a period in which the vehicle power supply is turned off immediately before, the absolute steering angle is calculated by taking into account the number of rotations of the motor obtained through the rotation detection circuit during the off period. A steering control device that calculates. The steering control device according to claim 4,
When the vehicle power is turned on, the main arithmetic unit is configured to determine whether at least one of the first abnormality detection circuit and the second abnormality detection circuit indicates an abnormality, and When the rotation of the motor is detected during a period in which the vehicle power supply is turned off immediately before being turned on, a steering control for invalidating a rotation speed of the motor detected by the rotation detection circuit during the off period. apparatus. In the steering control device according to claim 4 or 5,
The main calculation unit calculates a basic component of a target torque to be generated by the motor based on at least a steering torque as a state quantity indicating the steering state, and executes compensation control for the basic component based on the absolute steering angle. Thing,
The main processing unit is configured to execute the compensation control when a vehicle power supply is turned on and when at least one of the first abnormality detection circuit and the second abnormality detection circuit indicates an abnormality. To stop the steering control.

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