JP6066201B2 - Electronic control unit - Google Patents

Description

  The present invention estimates the temperature of the temperature estimation object based on the measurement value of the temperature measurement unit provided in the vicinity of the temperature estimation object, and maintains the power supply even after the power switch is turned off. The present invention relates to an electronic control device that continues to estimate temperature.

  For example, in an electronic control device for electric power steering that applies a steering assist force to an automobile steering system by an electric motor, as disclosed in Patent Documents 1 to 4, when the temperature of an object cannot be directly measured, In some cases, the temperature of the object is estimated based on the measurement value of the temperature measurement unit installed in the vicinity of the object. In this type of electronic control device, the overheat protection control of the electric motor is performed based on the estimated temperature when the power switch is turned on, but in order to protect the electric motor from overheating even after the power switch is turned off or abnormally stopped, Various measures have been taken.

  An electronic control device disclosed in Patent Document 1 includes a power supply self-holding unit that self-holds a power supply, a CPU that estimates a temperature of the motor from a current value flowing through the motor, and determines a current limit value of the electric motor based on the estimated temperature. It has. Then, after the power supply to the motor is cut off, the CPU calculates the self-holding time based on the estimated temperature of the motor, and until the self-holding time elapses, the power supply self-holding means self-holds the power, and the CPU Continues the temperature estimation process.

  The electronic control device disclosed in Patent Document 2 is a power self-holding means that can control its own power stop after power is turned on by a key switch, a temperature that estimates the temperature of the electric motor, and performs temperature control of the electric motor based on the estimated temperature. And an estimation means. Even if the power stop signal is input by the key switch, the power self-holding means keeps the power supply while the estimated temperature does not fall below the predetermined value, and the temperature estimating means continues the temperature estimation process.

  The electronic control device of Patent Literature 3 includes temperature estimation means for estimating the temperature of an electric motor or a heating element based on a detection value of a temperature sensor, and an EEPROM. Then, when the engine is stopped due to the engine stall, the estimated temperature of the temperature estimating means is recorded in the EEPROM, and when the steering wheel operation is resumed, the detected temperature of the temperature sensor and the estimated temperature recorded in the EEPROM are high. This is the initial value for the temperature estimation means to estimate the temperature.

  The electronic control device of Patent Document 4 includes a temperature estimation state storage unit and an initial value setting unit in addition to the power supply self-holding unit and the temperature estimation unit as in Patent Document 2. The temperature estimation state storage unit stores predetermined data indicating the state of the temperature estimation process in the storage unit before the temperature estimation unit stops. The initial value setting means sets an initial value of the estimated temperature value based on predetermined data in the storage unit when the ignition switch is turned on again and the temperature estimating means is activated.

JP-A-6-247324 JP 2002-362393 A JP 2005-263010 A No. 2008/153162

  In the electronic control devices disclosed in Patent Documents 1 and 2, the power is self-held after the power switch is turned off, and the temperature estimation process is continued. However, at that time, if any abnormality such as removal of the battery or disconnection of the power supply line occurs and the power supply of the electronic control device cannot be maintained, the temperature estimation process is interrupted. If the power switch is turned on after a short time, the overheat protection control cannot be performed properly, and the overheat protection target (electric motor) may be damaged due to overheating. In contrast, in Patent Documents 3 and 4, the temperature estimation initial value is set based on the temperature estimation information before the previous stop after the power switch is turned on.

  An object of the present invention is to provide an electronic control device capable of preventing the overheat protection target from failing due to overheating even when the temperature estimation process is interrupted because the power supply cannot be maintained due to an abnormality. is there.

An electronic control device according to the present invention is based on predetermined input information, a control unit that controls a control target, a temperature measurement unit installed in the vicinity of the temperature estimation target, and a temperature measurement unit based on a measurement value of the temperature measurement unit. The temperature estimation unit for estimating the temperature of the estimation detection target, the threshold storage unit for storing the overheat protection temperature threshold for detecting the overheat state of the temperature estimation target, and the estimated temperature and threshold storage unit of the temperature estimation unit are stored. Based on the result of comparison with the overheat protection temperature threshold, an output limiting unit for limiting the control output for the control unit to control the control target, a power supply self-holding unit for self-holding the power after the power switch is turned off, and normal Set according to the normal end storage unit for storing the completion, the normal end writing unit for writing the normal end in the normal end storage unit, the measured value of the temperature measurement unit and the estimated temperature of the temperature estimation unit Meet the prescribed conditions A condition determination unit that determines whether or not the normal end storage unit stores a normal end confirmation unit that checks whether or not the normal end storage unit stores the normal end, and an overheat protection temperature threshold value. And a threshold value writing unit that writes an abnormal time threshold value to the threshold value storage unit so as to detect an overheating state more strictly than the threshold value. When the condition determination unit determines that the predetermined condition has been satisfied after the power switch is turned off, the normal end writing unit writes the normal end storage unit to the normal end storage unit, and the power supply self-holding unit Stop holding. Further, when the power switch is turned on, when it is confirmed that the normal end confirmation unit stores the normal end in the normal end storage unit, the threshold writing unit overwrites the normal threshold in the threshold storage unit, When the normal end confirmation unit confirms that the normal end storage unit does not store the normal end information, the threshold value writing unit overwrites the threshold value storage unit with the abnormal threshold value.

  According to the above, even if the power estimation cannot be held due to the occurrence of an abnormality and the temperature estimation process is interrupted, it is not stored in the normal end storage unit when the power switch is turned on. The threshold value at the time of abnormality is stored in the threshold value storage unit as the overheat protection temperature threshold value. For this reason, based on the result of comparing the estimated temperature of the temperature estimation unit with the abnormal threshold value, the control output for the control unit to control the control target is severely restricted, and the overheat protection target is prevented from being damaged due to overheating. It becomes possible to do.

  In the present invention, in the electronic control device, the threshold value writing unit may overwrite the normal value threshold value in the threshold value storage unit after a predetermined time has elapsed after the abnormal value threshold value is overwritten in the threshold value storage unit.

  According to the present invention, in the above electronic control device, the self-holding time for setting the self-holding time for the power supply self-holding unit to self-hold the power based on the difference between the measured value of the temperature measuring unit and the estimated temperature of the temperature estimating unit. A time setting unit may be further provided, and the condition determination unit may determine whether the self-holding time has elapsed in a state where the power switch is off and the power supply self-holding unit holds the power supply as a predetermined condition. .

  In the present invention, in the electronic control device, the condition determination unit determines whether the difference between the measured value of the temperature measurement unit and the estimated temperature of the temperature estimation unit is less than a predetermined value as the predetermined condition. May be.

  Furthermore, in the present invention, the electronic control device may be an electric power steering control device mounted on a vehicle. In this case, the control object and the temperature estimation object are composed of an electric motor whose drive is controlled by an electric power steering control device in order to generate a steering assist force, and the power switch is composed of an ignition switch of the vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, even if it becomes impossible to carry out self-holding of a power supply by abnormality and a temperature estimation process is interrupted, the electronic control apparatus which can prevent a target object from failing by overheating can be provided. .

It is a block diagram of the electronic control apparatus by embodiment of this invention. 2 is a flowchart showing an operation of the electronic control device of FIG. 1. 2 is a flowchart showing an operation of the electronic control device of FIG. 1. It is the flowchart which showed the detail of the assist control process of FIG. 2A. It is the flowchart which showed the detail of the self-holding time setting process of FIG. 2B. It is a time chart at the time of normal of the electronic controller of FIG. It is a time chart at the time of abnormality of the electronic controller of FIG. It is the flowchart which showed operation | movement of the electronic control apparatus by other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  First, the configuration of the electronic control device 100 of the present embodiment will be described with reference to FIG.

  FIG. 1 is a block diagram of the electronic control device 100. The electronic control device 100 includes an ECU (electric power steering control device) used in the electric power steering system 200 of the automobile. The electronic control device 100 drives the electric motor 20 with the electric power of the battery 30 to apply a steering assist force to the steering system of the automobile.

  The electronic control device 100 includes a microcomputer 1, a power supply self-holding unit 2, a motor driving unit 3, a current detection unit 4, and a thermistor 5. The microcomputer 1 includes a motor control unit 6, an output limiting unit 7, a temperature estimation unit 8, a threshold storage unit 9, a self-holding time setting unit 10, a normal end storage unit 11, a normal end writing unit 12, a condition determination unit 13, A normal end confirmation unit 14, a threshold writing unit 15, a threshold confirmation unit 16, and a time measurement unit 17 are provided.

  Electric power is supplied to the electronic control device 100 from the battery 30 via an IG (ignition) switch 18. Electric power is supplied to the motor drive unit 3 from the battery 30 via a separate path from the IG switch 18.

  The motor controller 6 receives a steering torque from a torque sensor (not shown) and a vehicle speed from a vehicle speed sensor (not shown). The motor control unit 6 sets a current command value (control output) for controlling the electric motor 20 based on the input steering torque and vehicle speed.

  The motor drive unit 3 drives the electric motor 20 by causing a current to flow through the electric motor 20 based on a current command value input from the motor control unit 6 via the output limiting unit 7. The current detection unit 4 detects the value of the current flowing through the electric motor 20 and outputs it to the motor control unit 6. The motor control unit 6 performs feedback control of the electric motor 20 via the motor driving unit 3 based on the value of the current flowing through the electric motor 20.

  The motor control unit 6 is an example of the “control unit” in the present invention. The electric motor 20 is an example of the “control target” in the present invention.

  The thermistor 5 is installed in the vicinity of the electric motor 20. The temperature estimation unit 8 estimates the temperature of the electric motor 20 based on the measured value (temperature) of the thermistor 5. The thermistor 5 is an example of the “temperature measurement unit” in the present invention. The electric motor 20 is an example of the “temperature estimation target” in the present invention.

  The threshold storage unit 9 is composed of a nonvolatile memory. The threshold storage unit 9 stores an overheat protection temperature threshold for detecting the overheat state in order to protect the electric motor 20 from overheating. The threshold value writing unit 15 writes, as the overheat protection temperature threshold value, a normal time threshold value or an abnormal time threshold value that detects an overheat condition more strictly than the normal time threshold value in the threshold value storage unit 9.

  The output limiting unit 7 is a current command for the motor control unit 6 to control the electric motor 20 based on the result of comparing the estimated temperature of the temperature estimation unit 8 and the overheat protection temperature threshold value stored in the threshold value storage unit 9. Limit the value. The electric motor 20 is also an overheat protection target.

  Power is supplied from the battery 30 to the power supply self-holding unit 2 through a different path from the IG switch 18. After the IG switch 18 is turned off, the power supply self-holding unit 2 self-holds the power supply of the electronic control device 100. The IG switch 18 is an example of the “power switch” in the present invention.

  After the IG switch 18 is turned off, the temperature estimation process of the electric motor 20 is continued by the thermistor 5 and the temperature estimation unit 8 while the power supply is held by the power supply self-holding unit 2.

  The assist control process for generating the steering assist force by the motor control unit 6, the output limiting unit 7, the motor driving unit 3, the current detection unit 4, and the electric motor 20 is performed while the IG switch 18 is on, This is not done while switch 18 is off.

  Based on the measured value of the thermistor 5 and the estimated temperature of the temperature estimation unit 8, the self-holding time setting unit 10 sets a self-holding time during which the power supply self-holding unit 2 self-holds the power after the IG switch 18 is turned off. .

  The normal end storage unit 11 includes a nonvolatile memory. The normal end storage unit 11 is provided with a normal end flag 11a area. As will be described later, the normal end writing unit 12 turns on the normal end flag 11a to write the normal end in the normal end storage unit 11.

  As will be described later, the condition determination unit 13 determines whether or not a predetermined condition set based on the measured value of the thermistor 5 and the estimated temperature of the temperature estimation unit 8 is satisfied. When the condition determination unit 13 determines that the predetermined condition is satisfied, the normal end writing unit 12 turns on the normal end flag 11a, and the power supply self-holding unit 2 stops the power supply self-holding.

  When the IG switch 18 is turned on, the normal end confirmation unit 14 confirms whether or not the normal end storage unit 11 stores a normal end, that is, whether or not the normal end flag 11a is on.

  When the normal end confirmation unit 14 confirms that the normal end storage unit 11 stores information indicating the normal end, the threshold value writing unit 15 overwrites the threshold value storage unit 9 with the normal threshold value. When the normal end confirmation unit 14 confirms that the normal end storage unit 11 does not store the normal end information, the threshold value writing unit 15 overwrites the threshold value storage unit 9 with the abnormal threshold value.

  The threshold value confirmation unit 16 confirms the overheat protection temperature threshold value stored in the threshold value storage unit 9. The time measurement part 17 measures the predetermined time mentioned later.

  Next, the operation of the electronic control device 100 will be described with reference to FIGS. 2A to 6.

  2A and 2B are flowcharts showing the operation of the electronic control device 100. FIG. FIG. 3 is a flowchart showing details of the assist control process in step S15 of FIG. 2A. FIG. 4 is a flowchart showing details of the self-holding time setting process in step S18 of FIG. 2B. FIG. 5 is a time chart when the electronic control device 100 is normal. FIG. 6 is a time chart when the electronic control apparatus 100 is abnormal.

  Each process in FIGS. 2A to 4 is executed by the microcomputer 1 in FIG. 1 controlling each unit.

  First, when the IG switch 18 is turned on (step S1 in FIG. 2A, T1 in FIGS. 5 and 6), initial processing of each part of the electronic control device 100 is performed (step S2 in FIG. 2A). This initial process includes resetting of the power supply via the IG switch 18 (see FIGS. 5 and 6). When the initial processing of each unit is completed, the power supply self-holding unit 2 turns on (starts) power supply self-holding (step S3 in FIG. 2A, T2 in FIGS. 5 and 6).

  Next, the normal end confirmation unit 14 refers to the normal end storage unit 11 and confirms whether or not the normal end flag 11a is on (step S4 in FIG. 2A). If the normal end flag 11a is on (step S4 in FIG. 2A: YES), the threshold writing unit 15 overwrites the threshold value storage unit 9 with the normal threshold as the overheat protection temperature threshold (step S5 in FIG. 2A). ).

  Next, the normal end writing unit 12 rewrites the normal end flag 11a of the normal end storage unit 11 to OFF (step S8 in FIG. 2A, T3 in FIGS. 5 and 6). And the temperature estimation part 8 estimates the temperature of the electric motor 20 based on the measured value of the thermistor 5 (temperature estimation process of step S9 of FIG. 2A, T4 of FIG. 5 and FIG. 6). At this time, the temperature estimation initial value is a value obtained by adding a predetermined value to the measurement value of the thermistor 5.

  Next, when the threshold value confirmation unit 16 confirms that the normal time threshold value is stored as the overheat protection temperature threshold value in the threshold value storage unit 9 (step S10 in FIG. 2A: YES), the state is maintained (FIG. 5 and FIG. 5). T5 in FIG. 6).

  If the IG switch 18 remains on (step S14 in FIG. 2A: NO), assist control processing is performed by the motor control unit 6 or the like (step S15).

  Specifically, as shown in FIG. 3, when the steering torque and the vehicle speed of the steering are input to the microcomputer 1 (step S31: YES), the motor control unit 6 determines the current command value of the electric motor 20 based on the steering torque and the vehicle speed. Is set (step S32). Next, the output restriction unit 7 compares the estimated temperature estimated by the temperature estimation unit 8 with the overheat protection temperature threshold value (in this case, the normal time threshold value) stored in the threshold value storage unit 9 (step S33), Based on the comparison result, the current command value of the electric motor 20 is limited (step S34). Here, for example, the current command value of the electric motor 20 is decreased based on the difference between the estimated temperature and the overheat protection temperature threshold.

  Then, based on the limited current command value, the motor driving unit 3 drives the electric motor 20 (step S35). As a result, a steering assist force is applied to the steering system of the automobile, and the driver can operate the steering with a small force. Moreover, the actual temperature and estimated temperature of the electric motor 20 and the measured value of the thermistor 5 rise.

  When the steering torque is not input to the microcomputer 1 (step S31: NO), the processing of steps S32 to S35 is not executed, and the assist control processing is terminated.

  When the assist control process ends, the processes after step S9 in FIG. 2A are executed again.

  Thereafter, when the IG switch 18 is turned off (step S14 in FIG. 2A: YES, T6 in FIG. 5), the time measuring unit 17 starts measuring time (step S16 in FIG. 2B).

  At this time, as shown after T6 in FIG. 5, no power is supplied to the microcomputer 1 via the IG switch 18, but the power supply self-holding unit 2 self-holds the power, so that the power supply self-holding unit 2 From the battery 30 to the microcomputer 1. Further, the driving of the electric motor 20 is stopped, and the actual temperature and the estimated temperature of the electric motor 20 and the measured value of the thermistor 5 are lowered.

  Next, it is confirmed whether or not the self-holding time for holding the power supply by the power supply self-holding unit 2 is set by the self-holding time setting unit 10 (step S17 in FIG. 2B). At this time, if the self holding time is not set (step S17: NO), the self holding time setting unit 10 sets the self holding time based on the measured value of the thermistor 5 and the estimated temperature of the temperature estimating unit 8. (Step S18).

  Specifically, as shown in FIG. 4, first, the difference ΔT between the two values is calculated by subtracting the estimated temperature of the temperature estimating unit 8 from the measured value of the thermistor 5 (step S41). Based on the difference ΔT and the predetermined function f, the self-holding time is calculated (step S42).

  2B, the condition determination unit 13 refers to the self-holding time setting unit 10 and the time measuring unit 17, and the IG switch 18 is off and the power supply self-holding unit 2 holds the power supply. In the state, it is determined whether the self-holding time has elapsed. At this time, if the self-holding time has not elapsed (step S19: NO), the processing after step S9 in FIG. 2A is executed again.

  2B, if the self-holding time has elapsed (step S19: YES), the time measurement is stopped (step S20), and the normal end writing unit 12 rewrites the normal end flag 11a to ON. (Step S21, T7 in FIG. 5). Then, power supply self-holding by the power supply self-holding unit 2 is turned off (stopped) (step S22 in FIG. 2B, T8 in FIG. 5).

  On the other hand, if an abnormality occurs, for example, when the battery 30 is removed or the power line from the battery 30 is disconnected while the loop of steps S9 to S15 in FIG. 2A is being executed, the electronic control unit 100 is shut down. To do. For this reason, as shown in T10 of FIG. 6, the power supply via the IG switch 18 is turned off, and the self-holding of the power supply by the power supply self-holding unit 2 is also turned off (stopped). 2A and 2B is interrupted, temperature measurement by the thermistor 5 is stopped, and temperature estimation by the temperature estimation unit 8 is also stopped.

  Thereafter, when the power is restored and the electronic control device 100 is restarted, after confirming that the IG switch 18 is turned on (step S1 in FIG. 2A), initial processing of each part is performed (step in FIG. 2A). S2, T11 in FIG. 6).

  When the initial processing of each unit is completed, the power supply self-holding unit 2 turns on the power supply self-holding (step S3 in FIG. 2A, T12 in FIG. 6), and the normal end confirmation unit 14 checks the state of the normal end flag 11a ( Step S4 in FIG. 2A). At this time, the normal end flag 11a remains off in step S8 before restart (step S4: NO). For this reason, the threshold writing unit 15 overwrites the threshold storage unit 9 with the abnormal threshold as the overheat protection temperature threshold (step S6 in FIG. 2A, T13 in FIG. 6), and the time measurement unit 17 starts measuring the threshold return time. (Step S7 in FIG. 2A).

  Next, the normal end writing unit 12 keeps the normal end flag 11a off (step S8 in FIG. 2A), and the temperature estimation unit 8 estimates the temperature of the electric motor 20 (step S9 in FIG. 2A, FIG. 6). T14).

  Thereafter, the threshold value confirmation unit 16 confirms that the abnormal time threshold value is stored in the threshold value storage unit 9 as the overheat protection temperature threshold value (step S10 in FIG. 2A: NO). If the threshold return time has not elapsed (step S11: NO) and the IG switch 18 remains on (step S14: NO), an assist control process is performed (step S15).

  At this time, as described above, each process of FIG. 3 is executed. In step S33, the output restriction unit 7 detects the estimated temperature by the temperature estimation unit 8 and the overheat protection temperature threshold value (stored in the threshold value storage unit 9). In this case, an abnormal threshold value) is compared. Then, the current command value of the electric motor 20 is limited based on the comparison result (step S34). As a result, the current command value of the electric motor 20 is limited to be smaller than that in the normal state described above, and the temperature increase of the electric motor 20 is suppressed.

  Thereafter, when the threshold return time has elapsed (step S11 in FIG. 2A: YES, T15 in FIG. 6), the time measuring unit 17 stops measuring the threshold return time (step S12 in FIG. 2A), and the threshold writing unit 15 The normal threshold value is overwritten in the threshold value storage unit 9 as the overheat protection temperature threshold value (step S13).

  When the IG switch 18 is turned off (step S14: YES), as described above, the processing after step S16 in FIG. 2B is executed.

  In the above embodiment, when an abnormality occurs, the electronic control unit 100 of the electric power steering system 200 shuts down, and the power supply self-holding unit 2 cannot self-hold the power, and the temperature estimation process by the temperature estimation unit 8 is interrupted. Is done. However, when the IG switch 18 is subsequently turned on, the normal end storage unit 11 does not store the fact that the normal end has been completed (the normal end flag 11a is off), so that the threshold writing unit 15 sets the overheat protection temperature threshold value. The abnormal threshold value is written in the threshold value storage unit 9. For this reason, since the control output for controlling the steering assisting electric motor 20 is severely limited by the output limiting unit 7 based on the result of comparing the estimated temperature of the temperature estimating unit 8 and the abnormality threshold value, It is possible to prevent the motor 20 from being damaged due to overheating.

  In the above embodiment, the threshold value writing unit 15 overwrites the threshold value storage unit 9 with the normal time threshold when a predetermined threshold return time elapses after the abnormal value threshold value is written in the threshold value storage unit 9. For this reason, after the actual temperature of the electric motor 20 approaches the estimated temperature value, the normal threshold value can be reset in the threshold value storage unit 9 as the overheat protection temperature threshold value. And by controlling the electric motor 20 based on the result of comparing the estimated temperature of the temperature estimation unit 8 and the normal threshold value, the performance of the electric motor 20 can be sufficiently exhibited without impairing the performance. .

  Furthermore, in the above embodiment, the self-holding time setting unit 10 sets the self-holding time for the power supply self-holding unit 2 to self-hold the power based on the difference between the measured value of the thermistor 5 and the estimated temperature of the temperature estimation unit 8. It is set. When the condition determination unit 13 determines that the self-holding time has elapsed in a state where the IG switch 18 is off and the power supply self-holding unit 2 self-holds the power, the normal end writing unit 12 sets the normal end flag. 11a is turned on (a state in which normal termination is written), and the power supply self-holding unit 2 stops the power supply self-holding.

  As a result, after the self-holding time has elapsed, the actual temperature of the electric motor 20 decreases, and after the temperature approaches the estimated temperature of the temperature estimating unit 8, the self-holding of the power source and the temperature estimation are stopped, and the normal It can be recorded in the end storage unit 11 that the end is normal. Further, when the self-holding of the power source and the temperature estimation are interrupted due to the occurrence of an abnormality before the self-holding time elapses, it is not recorded in the normal end storage unit 11 that the normal end is completed (normal end flag 11a Off state). Then, when the IG switch 18 is turned on next time, the normal threshold value or the abnormal threshold value can be appropriately set in the threshold value storage unit 9 as the overheat protection temperature threshold value.

  The present invention can employ various embodiments other than those described above. For example, in the above embodiment, the normal end flag 11a is turned on when the self-holding time has elapsed with the IG switch 18 off and the power supply self-holding unit 2 holding the power supply. Is not limited to this. Other than this, for example, the following may be used. After the IG switch 18 is turned off (step S14 in FIG. 2A: YES), the condition determining unit 13 sets the difference (temperature difference) ΔT between the measured value of the thermistor 5 and the estimated temperature of the temperature estimating unit 8 as shown in FIG. Calculate (step S23). If the difference ΔT is less than the predetermined value (step S24: YES), the normal end flag 11a is turned on (step S21), and the self-holding of the power source by the power source self-holding unit 2 is stopped (step S22). If the difference ΔT is greater than or equal to the predetermined value (step S24: NO), the process returns to step S9.

  As a result, the actual temperature of the electric motor 20 decreases, and after the temperature approaches the estimated temperature of the temperature estimation unit 8, the self-holding of the power source and the temperature estimation are stopped, and the normal termination storage unit 11 is normally terminated. It can be recorded. When the difference between the measured value of the thermistor 5 and the estimated temperature of the temperature estimation unit 8 is greater than or equal to a predetermined value, if the self-holding of the power source and the temperature estimation are interrupted due to the occurrence of an abnormality, the normal end storage unit 11 Thus, it is possible not to record the fact of normal end (the normal end flag 11a is off). Then, when the IG switch 18 is turned on next time, the normal threshold value or the abnormal threshold value can be appropriately set in the threshold value storage unit 9 as the overheat protection temperature threshold value.

  Further, in the above embodiment, after the threshold value writing unit 15 writes the threshold value at the time of abnormality in the threshold value storage unit 9 and the threshold value recovery time elapses, the threshold value storage unit 9 is overwritten with the normal time threshold value, and overheat protection is performed. Although the example which changed the temperature threshold was shown, this invention is not limited only to this. In addition to this, for example, after the abnormality threshold value is written in the threshold value storage unit 9, the estimated temperature of the temperature estimation unit 8 falls below a predetermined value, or the difference between the estimated temperature of the temperature estimation unit 8 and the measured value of the thermistor 5 is When it becomes less than the predetermined value, the threshold value storage unit 9 may be overwritten with the normal time threshold value to change the overheat protection temperature threshold value.

  Moreover, although the example which used the thermistor 5 as a temperature measurement part was shown in the above embodiment, this invention is not limited only to this. In addition to this, for example, a measurement unit that measures the temperature based on the current value of the electric motor 20, a temperature detection element other than the thermistor 5, or the like may be used as the temperature measurement unit.

  In the above embodiment, the example in which the control target, the temperature estimation target, and the overheat protection target are the electric motor 20 has been shown. There may be. Further, the control target, the temperature estimation target, and the overheat protection target may be different from each other, or any two of them may be the same. For example, the temperature estimation target and the overheat protection target may be a heating element such as a relay or an electrolytic capacitor included in the motor driving unit 3, or may be a motor or an electric actuator separate from the electronic control device. . The control target may also be an electric motor or an electric actuator that is separate from the electronic control device.

  Furthermore, although the example which applied this invention to the electronic controller 100 of the electric power steering system 200 of a motor vehicle was given in the above embodiment, it is not restricted to this, For vehicles, household appliances, or other than this The present invention can also be applied to an electronic control device for OA (office automation) or the like.

2 Power supply self-holding unit 5 Thermistor 6 Motor control unit 7 Output limiting unit 8 Temperature estimation unit 9 Threshold storage unit 10 Self-holding time setting unit 11 Normal end storage unit 11a Normal end flag 12 Normal end writing unit 13 Condition determination unit 14 Normal End confirmation unit 15 Threshold writing unit 18 IG (ignition) switch 20 Electric motor 100 Electronic control unit

Claims (5)

A control unit that controls a control object based on predetermined input information;
A temperature measurement unit installed in the vicinity of the temperature estimation target;
Based on the measurement value of the temperature measurement unit, a temperature estimation unit that estimates the temperature of the temperature estimation target;
A threshold storage unit for storing an overheat protection temperature threshold for detecting an overheat state of the temperature estimation target ;
Based on the result of comparing the estimated temperature of the temperature estimation unit and the overheat protection temperature threshold stored in the threshold storage unit, the output limiting unit that limits the control output for the control unit to control the control target When,
A power supply self-holding unit for holding the power supply after turning off the power switch;
A normal end storage unit for storing the normal end;
A normal end writing unit for writing the normal end in the normal end storage unit;
A condition determination unit for determining whether or not a predetermined condition set based on the measurement value of the temperature measurement unit and the estimated temperature of the temperature estimation unit is satisfied;
A normal termination confirmation unit for confirming whether or not the normal termination storage unit stores a normal termination;
As the overheat protection temperature threshold value, a threshold value writing unit that writes a normal time threshold value or an abnormal time threshold value that is more severely detected than the normal time threshold value to the threshold value storage unit, and
When the condition determination unit determines that the predetermined condition is satisfied after the power switch is turned off, the normal end writing unit writes in the normal end storage unit that the normal end has been completed, and the power supply self-holding unit Stops self-holding of the power supply,
When the power switch is turned on, when the normal end confirmation unit confirms that the normal end storage unit stores the normal end, the threshold writing unit sets the normal threshold value to the threshold storage unit. When the normal end confirmation unit confirms that the normal end storage unit is not stored in the normal end storage unit, the threshold value writing unit overwrites the threshold value storage unit with the abnormal threshold value. An electronic control device characterized by that. The electronic control device according to claim 1.
The electronic control apparatus, wherein the threshold value writing unit overwrites the threshold value storage unit with the normal time threshold when a predetermined time elapses after the threshold value storage unit is overwritten with the abnormal time threshold value. The electronic control device according to claim 1 or 2,
Based on the difference between the measured value of the temperature measurement unit and the estimated temperature of the temperature estimation unit, the power supply self-holding unit further comprises a self-holding time setting unit that sets a self-holding time for self-holding the power supply,
The condition determining unit determines, as the predetermined condition, whether or not the self-holding time has elapsed in a state where the power switch is off and the power self-holding unit self-holds power. Electronic control device. The electronic control device according to claim 1 or 2,
The condition determination unit determines, as the predetermined condition, whether or not a difference between a measured value of the temperature measurement unit and an estimated temperature of the temperature estimation unit is less than a predetermined value. apparatus. The electronic control device according to any one of claims 1 to 4,
The electronic control device comprises an electric power steering control device mounted on a vehicle,
The control object and the temperature estimation object include an electric motor whose drive is controlled by the electric power steering control device in order to generate a steering assist force,
The electronic control device, wherein the power switch is an ignition switch of a vehicle.

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