JP6696314B2 - Power supply voltage abnormality determination device - Google Patents

Description

  The present invention relates to a power supply voltage abnormality determination device.

2. Description of the Related Art Conventionally, there has been known a technique for determining an abnormality in a power supply voltage in a load drive system that drives a load such as a motor by the electric power of a DC power supply such as a battery.
For example, in the technique disclosed in Patent Document 1, when the amount of decrease in the output voltage of the auxiliary power supply connected in series to the main power supply per unit time exceeds a predetermined amount of time decrease, the output destination of the power supply device, that is, An abnormality determination is performed to determine that the load side circuit is abnormal.
Here, the technique of Patent Document 1 is applied to an electric power steering device, and the device is downsized under conditions where the mounting space is severely restricted.

JP2012-91768A

Possible causes for the power supply voltage acquired by the determination device to be lower than normal are a short circuit abnormality in the load circuit and a power line disconnection abnormality in which the power source voltage applied to the load circuit is monitored. In the present specification, the “short circuit abnormality” is not limited to the state where the resistance is completely 0, but includes the state of “rare short” in which the resistance approaches 0 as compared with the normal state.
By the way, in reality, not only when a short circuit abnormality of the load circuit or a disconnection abnormality of the load circuit power supply line occurs, but also the voltage may momentarily drop due to chattering due to poor contact of wiring. In a vehicle equipped with an engine, in a system in which the same battery power is branched and supplied to an electric power steering motor and a starter, the power supply voltage may momentarily drop due to cranking at the time of engine start. ..

However, in the conventional technique of Patent Document 1, it is not possible to determine whether or not the cause of the abnormality in which the amount of decrease in the output voltage per unit time exceeds a predetermined amount of time decrease is a load circuit short circuit abnormality. Therefore, after that, even in the case of an instantaneous voltage drop in which the normal state is restored, if the system stop or the like is performed in the same manner as when the short circuit abnormality occurs, the system function is lost.
Further, in a motor drive device of an electric power steering device, generally, a power supply voltage applied to a load circuit and a power supply voltage applied to a control signal circuit are applied from the same DC power supply. Therefore, when the voltage of the load circuit drops, the voltage of the signal circuit drops at the same time. However, Patent Document 1 does not mention anything about the voltage drop of the signal circuit.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply voltage abnormality determination device capable of determining whether or not the cause of the abnormality in the load circuit voltage drop is a short circuit abnormality in the load circuit. To provide.

The power supply voltage abnormality determination device of the present invention is a load drive system in which a power supply voltage is applied to the load circuit (50) and the signal circuit (40) from the same DC power supply (10), and the load circuit voltage (V _LC ) and the signal. Monitor the circuit voltage (V _SC ). Here, the load circuit voltage is a power supply voltage applied to the load circuit, and the signal circuit voltage is a power supply voltage applied to the signal circuit.

This power supply voltage abnormality determination device includes an abnormality detection unit (60) and an abnormality determination unit (80).
Abnormality detection unit, the value of the load circuit voltage when lower than the voltage drop determination threshold (V _LC th), to detect "abnormal reduction state of the load circuit voltage".
The abnormality determination unit, when the abnormality of the load circuit voltage drop state is detected, changes the signal circuit voltage which is the difference between the signal circuit voltage value before the abnormality detection (V _SC _tr_pd) and the signal circuit voltage value after the abnormality detection. The cause of the voltage drop abnormality is determined based on the amount (ΔV _SC ).

More specifically, the abnormality determining unit determines that the signal circuit voltage change amount is equal to or more than the change amount threshold value (ΔV _SC _th) and is “a load circuit short-circuit abnormality”, and the signal circuit voltage change amount is less than the change amount threshold value. In this case, it is determined that “the load circuit has a power line disconnection abnormality or an instantaneous voltage drop”.
Accordingly, in the present invention, in a load drive system in which a power supply voltage is applied to the load circuit and the signal circuit from the same DC power supply, it is appropriately determined whether the cause of the load circuit voltage drop is a load circuit short circuit abnormality. Can be determined.

Preferably, when the signal circuit voltage change amount is less than the change amount threshold value, the abnormality determination unit further compares the load circuit voltage value with the normal recovery determination threshold value (V _LC re_th). Then, when the number of times (Cop) that the updated value of the load circuit voltage is determined to be less than the normal recovery determination threshold value is equal to or greater than a predetermined fixed value (Cop_fix), it is determined that "the power supply line disconnection abnormality of the load circuit" has occurred. judge.

Accordingly, when the cause of the voltage drop abnormality is not the load circuit short circuit abnormality, it is possible to further determine whether the load circuit is a power line disconnection abnormality or an instantaneous voltage drop.
Therefore, if the load circuit is short-circuited or the power line is broken, the drive of the load is stopped, and if the voltage drops momentarily, the drive of the load is continued. be able to.

1 is a schematic configuration diagram of a load drive system to which a microcomputer (power supply voltage abnormality determination device) of the first embodiment is applied. 3 is a control block diagram of the microcomputer of the first embodiment. FIG. The flowchart of load circuit voltage drop abnormality detection. The flowchart of the signal circuit voltage calculation process before abnormality detection. The flowchart of the voltage calculation process before abnormality detection which added the erroneous determination prevention measure. The timing chart of the signal circuit voltage calculation process before abnormality detection. 5 is a flowchart of cause determination and abnormality treatment when a load circuit voltage drop is abnormal. The timing chart of load circuit voltage drop abnormality treatment (short circuit abnormality). The timing chart of load circuit voltage drop abnormality treatment (disconnection abnormality). Timing chart of load circuit voltage drop abnormality treatment (instantaneous voltage drop). FIG. 6 is a control block diagram of the microcomputer according to the second embodiment having a plurality of input voltage processing units. The flowchart of the majority vote process by a several input voltage process part. The flowchart of (a) minimum value, (b) maximum value, and (c) average value calculation by a several input voltage process part.

Hereinafter, an embodiment of a power supply voltage abnormality determining device will be described with reference to the drawings. In each embodiment, the microcomputer functions as a “power supply voltage abnormality determination device”.
(First embodiment)
The power supply voltage abnormality determination device of the first embodiment will be described with reference to FIGS. 1 to 10.
First, with reference to FIG. 1, an overall configuration of a load drive system to which a microcomputer 43 as a “power supply voltage abnormality determination device” is applied will be described. This load drive system is used, for example, as a system for driving a steering assist motor in an electric power steering device of a vehicle.
In the example of FIG. 1, the microcomputer 43 configures the ECU 30 that controls the drive target 55 together with the regulator 42, the driver circuit 44, the load drive circuit 54, and the like. For example, the load drive circuit 54 is an inverter or the like that converts DC power into AC power, and the drive target 55 is a motor or the like that generates torque by the power supplied from the inverter. Here, the load drive circuit 54 and the drive target 55 are considered as a “load 56” as a control target of the ECU 30.

In FIG. 1, a circuit including a load drive circuit 54 and a load 56, which is supplied with a power current from the load circuit connector 36 via the load circuit power supply line 37, is defined as a “load circuit 50”. A circuit including the microcomputer 43 and the driver circuit 44, which operates based on the power supply voltage input from the signal circuit connector 31 via the signal circuit power supply line 32 and the regulator 42, is defined as a “signal circuit 40”. .. The circuit from the signal circuit connector 31 to the regulator 42 may be interpreted as a “signal circuit” in a narrow sense.
Hereinafter, the power supply voltage applied to the load circuit 50 is referred to as “load circuit voltage V _LC ”, and the power supply voltage applied to the signal circuit 40 is referred to as “signal circuit voltage V _SC ”. “LC” means “Load Circuit”, and “SC” means “Signal Circuit”.

  The ECU 30 has two connectors 31, 32 to which DC power is input from the same battery 10. The positive electrode of the battery 10 is connected to a power supply voltage terminal of a signal circuit connector 31 via a power supply fuse 21 for a signal circuit and an external switch 22 such as an ignition switch. The positive electrode of the battery 10 is connected to the power supply voltage terminal of the load circuit connector 36 via the power supply fuse 26 for the load circuit. The negative electrode of the battery 10 is connected to the ground terminals of the signal circuit connector 31 and the load circuit connector 36.

Inside the ECU 30, a regulator 42, a microcomputer 43, a driver circuit 44, load circuit power supply relay switches 51 and 52, a load drive circuit 54, and the like are provided.
The regulator 42 generates a microcomputer power supply based on the signal circuit voltage V _SC input via the signal circuit power supply line 32.
The microcomputer 43 is driven by the microcomputer power supply generated by the regulator 42, and calculates a command signal to the driver circuit 44 by various control calculations. Note that illustration of signal inputs of vehicle information and feedback information used for control calculation is omitted.
The driver circuit 44 operates the load circuit power supply relay switches 51 and 52 and the switches in the load drive circuit 54 based on the command signal calculated by the microcomputer 43.

  The load drive circuit 54 is connected to the load circuit connector 36 via the load circuit power supply line 37. The load circuit power supply relay switches 51 and 52 are provided in the middle of the load circuit power supply line 37 and can interrupt the load circuit power supply line 37. The power circuit relay switches 51 and 52 for the load circuit function when the polarity of the battery 10 is connected in the positive direction and the normal power relay switch 51, and when the polarity of the battery 10 is incorrectly connected in the reverse direction. It is composed of a relay switch 52 for preventing reverse connection.

Further, the microcomputer 43 of the present embodiment monitors the signal circuit voltage V _SC via the signal circuit voltage monitoring line 34 connected to the monitoring point 41 of the signal circuit power supply line 32. Further, the microcomputer 43 monitors the load circuit voltage V _LC via the load circuit voltage monitoring line 38 connected to the monitoring point 53 of the load circuit power supply line 37.

In the present specification, the short circuit abnormality of the load circuit is included including the following phenomena.
(A) When the drain-source of the switching element that constitutes the inverter is short-circuited.
(B) When the motor winding of either phase is short-circuited to the power supply line of the inverter or grounded to the ground line of the inverter.
(C) When the motor windings of different phases are short-circuited between the phases.
In all cases, the “short circuit abnormality” is not limited to the state where the resistance is completely 0, but includes the state of “rare short” in which the resistance approaches 0 as compared with the normal state. When a short circuit abnormality occurs, an element, a board component, or the like may be destroyed due to overcurrent or heat generated due to the overcurrent. This is called "system destruction".

Further, the case where the battery 10 and the monitoring point 53 are disconnected is referred to as "power line disconnection abnormality of load circuit". In the description of the embodiment, the “power supply line” is omitted and simply referred to as “load circuit disconnection abnormality”. That is, the disconnection on the load 56 side from the monitoring point 53, for example, the open failure of the switching element forming the inverter and the disconnection of the motor winding are not included in the “disconnection abnormality of the load circuit” in the present embodiment.
The "wire breakage abnormality" is not limited to the state where the resistance becomes infinite, but includes the state where the resistance becomes extremely large compared to the normal state.
Hereinafter, when the term “short circuit / disconnection abnormality of load circuit” is used, the description of the load circuit reference numeral “50” is omitted.

When there is a short circuit abnormality or a wire breakage abnormality, the load circuit voltage value V _LC monitored by the microcomputer 43 via the load circuit voltage monitoring line 38 is lower than in a normal state. Therefore, the microcomputer 43 can detect these abnormalities based on the decrease in the load circuit voltage value V _LC . When an abnormality occurs, the ECU power is turned off and appropriate measures such as stopping the system are taken to prevent the system from being destroyed.

By the way, in reality, not only when a short circuit abnormality of the load circuit or a disconnection abnormality of the load circuit power supply line occurs, but also the voltage may momentarily drop due to chattering due to poor contact of wiring. In a vehicle equipped with an engine, in a system in which electric power of the same battery is branched and supplied to an electric power steering motor and a starter, the power supply voltage may momentarily drop due to cranking when the engine is started. ..
If the system is stopped every time in the case of such an instantaneous voltage drop, the function originally required for the system, for example, the steering assist function in the electric power steering device is lost, and the convenience of the user is impaired.

For example, Japanese Patent Application Laid-Open No. 2012-91768, which is a conventional technique, discloses a technique of determining an abnormality in an output destination of a power supply device based on a reduction amount of an output voltage per unit time. In the case of an instantaneous voltage drop due to chattering or the like, erroneous determination may occur.
In addition to the above, various methods have been conventionally proposed for determining a power supply voltage drop abnormality. However, in most of them, one voltage level is monitored, and when the monitored voltage drops, it is determined to be abnormal and the driving of the load circuit is stopped.
In contrast to such a conventional technique, the microcomputer 43 of the present embodiment detects a decrease in the load circuit voltage V _LC , and the cause of the voltage decrease is any one of a load circuit short circuit abnormality, a disconnection abnormality, or an instantaneous voltage reduction. It is possible to determine whether there is any.

Next, details of the power supply voltage abnormality determination by the microcomputer 43 will be described.
In FIG. 2 showing the detailed configuration of the microcomputer 43, “V _LC ” means “load circuit voltage” or “load circuit voltage value”, and “V _SC ” is “signal circuit voltage” or “signal circuit voltage value”. Means. The presence or absence of “value” is used properly according to the context. For example, when describing a change in a physical quantity such as "the voltage drops", "value" is not attached. In addition, when comparing values such as "voltage value is larger than threshold value", "value" is attached.

The microcomputer 43 roughly has three functional units, that is, a load circuit voltage drop abnormality detection unit 60, a pre-abnormality detection signal circuit voltage calculation unit 70, and a load circuit voltage drop abnormality determination unit 80.
In the present embodiment, in order to distinguish between the configuration related to the load circuit voltage V _{LC and the} configuration related to the signal circuit voltage V _SC , the names of the respective parts tend to be inevitably long. Therefore, the official name is described at the first appearance, and the parts that can be understood even if omitted are omitted as appropriate.

First, in the present embodiment, the only voltage at which the "decrease abnormality" is detected is the load circuit voltage _VLC . Incidentally, the signal circuit voltage V _SC is simply determined whether it is within the normal value range or outside the normal value range. Further, the abnormality that is the detection target of the load circuit voltage V _LC is limited to the “voltage drop abnormality”. Therefore, the load circuit voltage drop abnormality detection unit 60 is omitted as the "abnormality detection unit 60", and the load circuit voltage drop abnormality determination unit 80 is omitted as the "abnormality determination unit 80". This abbreviated name corresponds to the "abnormality detection unit" and the "abnormality determination unit" described in the claims.

Further, “before abnormality detection” of the signal circuit voltage calculation unit 70 before abnormality detection means before decrease abnormality detection of the load circuit voltage V _LC , and therefore the only voltage to be calculated at this stage is the signal circuit voltage V _SC. Absent. Therefore, the pre-abnormality detection signal circuit voltage calculation unit 70 is omitted as the “pre-abnormality detection voltage calculation unit 70”. This abbreviated name corresponds to the “pre-abnormality detection voltage calculation unit” described in the claims.

The load circuit voltage V _LC monitored by the microcomputer 43 via the load circuit voltage monitoring line 38 shown in FIG. 1 is acquired by the abnormality detection unit 60 and the abnormality determination unit 80. Further, the signal circuit voltage V _SC monitored by the microcomputer 43 via the signal circuit voltage monitoring line 34 is acquired by the pre-abnormality detection voltage calculation unit 70 and the abnormality determination unit 80.

The abnormality detection unit 60 includes a load circuit voltage drop determination unit 61 and a drop state abnormality determination unit 62.
The load circuit voltage drop determination unit 61 determines that the load circuit voltage V _LC has dropped _{below a} predetermined voltage drop determination threshold value. The drop state abnormality determination unit 62 determines the load circuit voltage drop state abnormality using a counter that counts the number of times of voltage drop abnormality determination. Then, the drop state abnormality determination unit 62 outputs information on normality / abnormality of the load circuit voltage drop state.

The pre-abnormality detection voltage calculation unit 70 includes a pre-abnormality detection voltage value use permission determination unit 71, a pre-abnormality detection voltage buffer calculation unit 72, and a voltage buffer cancellation timer processing unit 73. In FIG. 2, as described in the name of the block as “V _SC ”, “voltage” or “voltage value” in the names of these units 71, 72, 73 means “signal circuit voltage” or “signal circuit”. It means "voltage value".

The pre-abnormality voltage value use permission determining unit 71 uses the “pre-abnormality signal circuit voltage value” used by the abnormality determining unit 80 to calculate the signal circuit voltage change amount ΔV _SC when an abnormality in the load circuit voltage drop state is detected. The use permission is determined for “V _{SC —} tr — pd”. In addition, "tr" in a symbol means "trouble", and "pd" means "pre-detection".
That is, it is assumed that the signal circuit voltage value V _SC _tr_pd before abnormality detection is not stable immediately after the power is turned on, or is decreased as the load circuit voltage V _LC is decreased. In such a case, if the abnormality determination unit 80 calculates the signal circuit voltage change amount ΔV _SC based on the voltage value V _SC _tr_pd, there is a possibility that an erroneous determination may occur.

Therefore, the pre-abnormality detection voltage value use permission determination unit 71 outputs the pre-abnormality detection signal circuit voltage value V _SC _tr_pd that can be appropriately used in the abnormality determination by the abnormality determination unit 80.
As means for that purpose, the pre-abnormality detection voltage buffer calculation unit 72 calculates the buffer value V _SC _tr_pd_bf of the pre-abnormality detection signal circuit voltage. The voltage buffer release timer processing unit 73 counts up the timer from the start of the voltage buffer to the release.

The abnormality determination unit 80 includes a signal circuit voltage change amount calculation unit 81, a load circuit short circuit determination unit 82, and a load circuit disconnection determination unit 83. When the abnormality detection unit 60 detects an abnormality in the load circuit voltage drop state, the abnormality determination unit 80 determines the cause of the abnormality and takes an abnormal action.
The signal circuit voltage change amount calculation unit 81 includes the pre-abnormality-detection voltage circuit voltage value V _SC _tr_pd output from the pre-abnormality-detection voltage value use permission determination unit 71 of the pre-abnormality-voltage calculation unit 70 and the signal circuit voltage after the abnormality detection. The “signal circuit voltage change amount ΔV _SC ”, which is the difference from the value V _SC , is calculated. That is, it is expressed as “ΔV _SC = V _SC —tr_pd−V _SC ”.

The load circuit short-circuit determination unit 82 determines whether or not there is a load circuit short-circuit abnormality based mainly on the signal circuit voltage change amount ΔV _SC . When it is determined that the load circuit is short-circuited abnormally, the load circuit short-circuit determination unit 82 outputs an ECU power off signal.
When the load circuit short circuit determination unit 82 determines that the load circuit short circuit abnormality is not the load circuit short circuit abnormality, the load circuit short circuit determination unit 83 uses a counter that counts the number of times of the wire circuit abnormality determination to determine whether the load circuit short circuit abnormality occurs. Determine. When it is determined that the load circuit has a disconnection abnormality, the load circuit disconnection determination unit 83 outputs an ECU power off signal.
On the other hand, when it is determined that the load circuit is not a disconnection abnormality but an instantaneous voltage drop, the load circuit disconnection determination unit 83 outputs an ECU normal signal.

  Next, the processing of each functional unit 60, 70, 80 will be described in order with reference to the flowcharts and timing charts of FIGS. In the description of each flowchart, the symbol "S" means a step. These processing routines are repeatedly executed at a predetermined cycle while the ECU power is on, or by using some signal as a trigger.

<Abnormality detection part>
FIG. 3 shows a flowchart of load circuit voltage drop abnormality detection by the abnormality detection unit 60.
In S11, the load circuit voltage drop determination unit 61 compares the load circuit voltage value V _LC with the voltage drop determination threshold value V _LC th.
When the load circuit voltage value V _LC is less than the voltage drop determination threshold value V _LC th and YES is obtained in S11, the process proceeds to S12. When the load circuit voltage value V _LC is equal to or higher than the voltage drop determination threshold value V _LC th and NO in S11, the process proceeds to S15, and the abnormality determination count value Ctr is set to 0 times. If the abnormality determination count value Ctr has been counted up in the routine up to the previous time, the count value Ctr is reset in S15.

In S12, the lowered state abnormality determination unit 62 determines whether or not the abnormality determination count value Ctr has reached a predetermined fixed value Ctr_fix. When the abnormality determination count value Ctr has not reached the definite value Ctr_fix, NO is determined in S12, and the count value Ctr is incremented in S14. In the following flowchart, the increment is indicated by the symbol "++".
When the abnormality determination count value Ctr reaches the fixed value Ctr_fix, YES is determined in S12, and it is determined that the "current value of the load circuit voltage drop state" is abnormal in S13.
Further, the time from when the abnormality determination count value Ctr reaches 0 to the fixed value Ctr_fix is referred to as “voltage drop abnormality fixed waiting time Ttr_fix”. The voltage drop abnormality confirmation waiting time Ttr_fix is referred to in the timing charts of FIGS. 6 and 8 to 10 described later.

<Voltage calculation unit before abnormality detection>
4 to 6 show a flowchart and a timing chart of the pre-abnormality detection signal circuit voltage calculation processing by the pre-abnormality detection voltage calculation unit 70. In FIG. 4, S23 and S24 are omitted in order to correspond step numbers to those in FIG. 5 described later.
In the examples shown in FIGS. 4 to 6, before the abnormality detection, when the update processing of the signal circuit voltage value V _SC _tr_pd before abnormality detection is executed every 1 [ms] and the decrease of the load circuit voltage V _LC is detected. The signal circuit voltage value V _SC _tr_pd is updated. The update cycle of 1 [ms] may be changed according to the system.

When the AND conditions are satisfied for the following three conditions, the pre-abnormality-state voltage value use permission determination unit 71 determines YES in S21, and proceeds to S22. If the AND condition is not satisfied for the three conditions, the abnormality value before voltage detection use permission determination unit 71 determines NO in S21, skips S22, and proceeds to S25.
<Condition 1> The voltage buffer use permission timer value Tap is the judgment time X [ms] or more. <Condition 2> The current value of the load circuit voltage drop state is abnormal. <Condition 3> The previous value of the load circuit voltage drop state is normal. "Ap" of the buffer use permission timer value Tap means "approval".

In S22, the voltage buffer usage permission judgment time X [ms] before the voltage buffer value _{V SC _tr_pd_bf (X [ms]} ) is updated as the abnormality detection before the signal circuit voltage V _SC _tr_pd. At this time, voltage buffer values older than X [ms] before are discarded.
Abnormality detection before voltage buffer calculation unit 72, in S25, step S26 updates the voltage buffer value V _SC _tr_pd_bf, acquired latest signal circuit voltage V _SC voltage buffer value V _SC _tr_pd_bf (0 [ms] before) Will be updated as.

In S27, it is determined whether the current value of the load circuit voltage drop state is abnormal.
When the current value of the load circuit voltage drop state is abnormal and YES in S27, the voltage buffer release timer processing unit 73 sets the voltage buffer use permission timer value Tap to 0 [ms] in S29. That is, the voltage buffer is released due to the occurrence of an abnormality in the load circuit voltage drop state.

When the current value of the load circuit voltage drop state is normal and NO in S27, the voltage buffer release timer processing unit 73 determines in S28 that the voltage buffer use permission timer value Tap is the voltage buffer use permission determination time X [ms]. To determine whether or not.
If the voltage buffer use permission timer value Tap has not reached the determination time X and YES is obtained in S28, the timer value Tap is incremented in S30. That is, the time obtained by adding 1 [ms] to the previous timer value Tap is updated as a new timer value Tap.
When the voltage buffer use permission timer value Tap has reached the determination time X and the answer is NO in S28, the voltage buffer release timer processing unit 73 ends the timer operation.

Next, FIG. 5 shows a flowchart of the before-abnormality-detection signal circuit voltage calculation processing in which an erroneous determination prevention measure is added to the processing of FIG. 4, and differences from the processing of FIG. 4 will be described.
In the process of FIG. 5, S23 is executed after S22. In S23, the pre-abnormality detection voltage buffer operation unit 72 determines whether or not the system power-on duration Tsys_on has reached the system voltage stabilization wait time Tsys_th.

When the system power-on duration Tsys_on has not reached the stabilization waiting time Tsys_th and the result in S23 is YES, the process proceeds to S24. In S24, the default voltage value V _SC _def is used as the pre-abnormality detection signal circuit voltage buffer value V _SC _tr_pd_bf (0 to X [ms]) 0 to X [ms] ago. The default voltage value V _SC _def is set so that the load circuit short-circuit determination unit 82 of the abnormality determination unit 80 can reliably determine that the load circuit is short-circuited.
On the other hand, if the system power-on duration Tsys_on has reached the stabilization waiting time Tsys_th and the answer is NO in S23, the process proceeds to S25. Hereinafter, it is the same as that of FIG.

The timing chart of FIG. 6 shows the system power supply, the signal circuit voltage V _SC , the load circuit voltage V _LC , and the system power-on duration Tsys_on in order from the top. Further shows the abnormality detection before the signal circuit voltage buffer value V _SC _tr_pd_bf, voltage buffer grant timer value the Tap, normality / abnormality of the load circuit brownout conditions, the abnormality detection before the signal circuit voltage V _SC _tr_pd. Abnormality detection before the signal circuit voltage buffer value V _SC _tr_pd_bf is the value from the previous voltage buffer usage permission judgment time X [ms] to 0 [ms] before. Here, the voltage buffer use permission determination time X [ms], the system voltage stabilization wait time Tsys_th, the default voltage value V _SC _def, etc. are set for each system.

The values on the time axis in FIG. 6 are described as discrete values for each 1 [ms].
The part from the time t0 to the time t2 is referred to for the explanation of the “pre-abnormality detection signal circuit voltage calculation processing after system power-on”. Further, the portion after time t5 is related to “abnormality detection before signal circuit voltage calculation processing after normal recovery from instantaneous voltage drop” related to FIG. 10 described later.
It should be noted that, from time t3 to time t5, the description of the operation of returning to normal after the load circuit voltage value V _LC temporarily falls below the voltage drop determination threshold value V _LC th is omitted here.
Further, the S numbers in the description indicate steps in the flowcharts of FIGS. 4 and 5.

Before the system power is turned on before time t0, the signal circuit voltage value V _SC and the load circuit voltage value V _LC are naturally 0 [V]. At time t0, the system power supply is turned on by the external switch, and at the same time, the signal circuit voltage value V _SC rises. In the example of FIG. 6, the load circuit voltage value V _LC rises 1 [ms] after the system power is turned on.
From time t0 to time t1 when the system power-on duration Tsys_on reaches the system voltage stabilization wait time Tsys_th, the default voltage value V _SC _def is used as the pre-abnormality detection signal circuit voltage value V _SC _tr_pd.

  At time t1, when the system power-on duration Tsys_on reaches the system voltage stabilization wait time Tsys_th, it is determined that the system voltage is stable, and the voltage buffer is started. That is, the voltage buffer release timer processing unit 73 starts counting up the voltage buffer use permission timer value Tap.

At time t2 when the voltage buffer use permission determination time X [ms] has elapsed from time t1, the voltage buffer use permission timer value Tap reaches the voltage buffer use permission determination time X [ms]. Then, the pre-abnormality detection voltage value use permission determination unit 71 determines that the voltage buffer value V _{SC —} tr_pd_bf (before X [ms]) can be used.

Therefore, when the voltage drop abnormality determination is confirmed at time t4 after the voltage drop abnormality is detected at time t3, the voltage buffer value V _{SC —} tr_pd_bf (before X [ms]) is determined to be the signal circuit voltage before abnormality detection at S22. It is used as the value V _SC _tr_pd.
At this time, at the same time, the voltage buffer release timer processing unit 73 initializes the voltage buffer use permission timer value Tap in S29.
After that, at time t5 when the load circuit voltage value V _LC returns to normal, the voltage buffer release timer treatment unit 73 starts counting up the voltage buffer use permission timer value Tap again.

<Abnormality determination part>
FIG. 7 shows a flowchart of the cause determination and the abnormality treatment by the abnormality determination unit 80 when the load circuit voltage is abnormally low.
The determination result of "the load circuit voltage drop state current value is abnormal?" In S41 is YES, which is a prerequisite for executing the process by the abnormality determining unit 80. If NO in S41, the routine of FIG. 7 ends.
In S42, the signal circuit voltage change amount calculation unit 81 calculates the signal circuit voltage change amount ΔV _SC by subtracting the current, ie, the signal circuit voltage value V _SC after the abnormality detection from the signal circuit voltage value V _SC _tr_pd before the abnormality detection. To do. If the signal circuit voltage value V _SC after the abnormality is detected is slightly lower than that before the abnormality is detected, the signal circuit voltage change amount ΔV _SC becomes a positive value.

When the OR condition is satisfied for the following three conditions, the load circuit short circuit determination unit 82 determines YES in S43, that is, the load circuit short circuit abnormality, and proceeds to S44. If the OR condition is not satisfied for the three conditions, the load circuit short circuit determination unit 82 determines NO in S43, and proceeds to S45.
<Condition 1> The signal circuit voltage change amount ΔV _SC is equal to or more than the short circuit judgment change amount threshold ΔV _SC _th <Condition 2> The signal circuit voltage value V _SC is outside the normal value range <Condition 3> The load circuit voltage value V _LC is the short circuit judgment voltage Below threshold _VLC sh_th In S44, the ECU power supply is turned off.

In S45, the load circuit disconnection determination unit 83 compares the load circuit voltage value V _LC with the normal recovery determination voltage threshold V _LC re_th. Note that "re" means "return".
When the load circuit voltage value V _LC is less than the normal recovery determination voltage threshold V _LC re_th and YES in S45, the process proceeds to S46, and the load circuit disconnection determination unit 83 increments the load circuit disconnection count value Cop. Note that “op” means “open”.
Subsequently, in S47, the load circuit disconnection determination unit 83 determines whether or not the load circuit disconnection count value Cop has reached a predetermined fixed value Cop_fix.

When the load circuit disconnection count value Cop has not reached the definite value Cop_fix, NO is determined in S47, the updated values of the signal circuit voltage value V _SC and the load circuit voltage value V _LC are acquired in S48, and before S42. Return to. That is, during the waiting time until the disconnection abnormality of the load circuit is determined, the presence or absence of the short circuit abnormality is re-determined in S43, and if NO in S43, the disconnection abnormality of the load circuit is re-determined in steps S45 and below.

When the load circuit disconnection count value Cop reaches the definite value Cop_fix, YES is determined in S47 and the disconnection abnormality of the load circuit is confirmed. Then, the process proceeds to S44, and the ECU power is turned off as in the case of the short circuit abnormality.
When the load circuit voltage value V _LC is equal to or higher than the normal recovery determination voltage threshold V _LC re_th and NO in S45, the load circuit disconnection determination unit 83 determines that the cause of the voltage drop abnormality is an instantaneous voltage drop such as chattering. The determination is made, and the process proceeds to S49.
In S49, the operation of the ECU 30 is continued.

FIG. 8, FIG. 9, and FIG. 10 are timing charts of the cause determination and the abnormality treatment when the abnormality causes are a short circuit abnormality, a disconnection abnormality, and an instantaneous voltage drop. The vertical axis of each figure is, in order from the top, the load circuit voltage V _LC , the normal / abnormal state of the load circuit voltage drop state, the signal circuit voltage V _SC , the signal circuit voltage value V _SC _tr_pd before the abnormality detection, and the load circuit disconnection count value Cop. , And ON / OFF of the ECU power supply. The S numbers in the description indicate steps in the flowchart of FIG. 7.

Commonly on the time axis of each figure, in the initial stage before time t3, the load circuit voltage value V _LC is higher than the voltage drop determination threshold value V _LC th, and the voltage drop state is normal. Abnormality detection before the signal circuit voltage V _SC _tr_pd has a default voltage value V _SC _def indicated by a broken line. The load circuit disconnection count value Cop is 0, and the ECU power supply is on.

At time t3, it is detected that the load circuit voltage V _LC has dropped _{below the} voltage drop determination threshold V _LC th due to some cause of abnormality. At this time, the signal circuit voltage buffer value V _SC _tr_pd_bf (X [ms] before) is assumed to be enabled. Therefore, at time t4, which is after the voltage drop abnormality confirmation waiting time Ttr_fix from time t3, the signal circuit voltage value V _SC before the voltage buffer use permission determination time X [ms] is set as the pre-abnormality detection signal circuit voltage value V _SC _tr_pd. It
The operation after time t4 will be described for each cause of abnormality.

In the case of the short circuit abnormality shown in FIG. 8, at time t3, the load circuit voltage V _LC drops and the signal circuit voltage V _SC also drops at the same time. Therefore, the signal circuit voltage change amount ΔV _SC (= V _SC _tr_pd−V _SC ) calculated at time t4 is equal to or greater than the short circuit determination change amount threshold value ΔV _SC _th. Therefore, the load circuit short circuit determination condition is satisfied in S43. Therefore, the load circuit short-circuit determination unit 82 of the abnormality determination unit 80 determines that the cause of the abnormality is a load circuit short-circuit abnormality, and turns off the ECU power supply.

In the case of the disconnection abnormality shown in FIG. 9 and the instantaneous voltage drop shown in FIG. 10, when the load circuit voltage V _LC drops at time t3, the signal circuit voltage V _SC does not change. Therefore, the signal circuit voltage change amount ΔV _SC (= V _SC _tr_pd−V _SC ) calculated at time t4 is less than the short circuit determination change amount threshold value ΔV _SC _th. Further, the signal circuit voltage value V _SC at time t3 is within the normal value range, and the load circuit voltage value V _LC is greater than or equal to the short circuit determination voltage threshold V _LC sh_th. Therefore, the load circuit short-circuit determination condition is not satisfied in S43.
Further, since the load circuit voltage value V _LC at time t4 is less than the normal recovery determination voltage threshold V _LC re_th, YES is determined in S45 and the load circuit disconnection count value Cop starts to be incremented.

In the case of the disconnection abnormality shown in FIG. 9, after the time t4, the state where the load circuit voltage value V _LC is less than the normal recovery determination voltage threshold V _LC re_th continues. Further, since the signal circuit voltage value V _SC and the signal circuit voltage change amount ΔV _SC are constant, “S45: YES → S46 → S47: NO → S48 → S42 until the load circuit disconnection count value Cop reaches the definite value Cop_fix. → S43: NO → S45 ”loop is repeated. Then, at time t6 when the load circuit disconnection count value Cop reaches the fixed value Cop_fix, the load circuit disconnection determination condition is satisfied in S47. Therefore, the load circuit disconnection determination unit 83 of the abnormality determination unit 80 determines that the cause of the abnormality is the load circuit disconnection abnormality, and turns off the ECU power supply.

In the case of the instantaneous voltage drop shown in FIG. 10, at time t5 after time t4, the load circuit voltage value V _LC becomes a normal value equal to or higher than the normal recovery determination voltage threshold V _LC re_th. Then, NO is determined in S45, and the increment of the load circuit disconnection count value Cop is stopped. Further, the on state of the ECU power supply is maintained and the system operation is continued.

(effect)
The effects of the first embodiment will be described. In the part of the effect explanation, in order to correspond to the description of the claims, “abnormality of disconnection of power supply line of load circuit” is described without being omitted.
(1) The abnormality determination unit 80 determines that the load circuit is short-circuited abnormally when the signal circuit voltage change amount ΔV _SC is greater than or equal to the change amount threshold ΔV _{SC —} th. On the other hand, when the signal circuit voltage change amount ΔV _SC is less than the change amount threshold ΔV _SC _th, it is determined that “the power supply line disconnection abnormality of the load circuit or the instantaneous voltage drop”.
Accordingly, in the load drive system in which the power supply voltage is applied from the same battery 10 to the load circuit 50 and the signal circuit 40, it is appropriately determined whether the cause of the load circuit voltage drop abnormality is a load circuit short circuit abnormality. be able to.

(2) When the signal circuit voltage change amount ΔV _SC is less than the change amount threshold ΔV _SC _th, the abnormality determination unit 80 further compares the load circuit voltage value V _LC with the normal recovery determination threshold V _LC re_th. Then, when the number of times Cop determined that the updated value of the load circuit voltage V _LC is less than the normal recovery determination threshold V _LC re_th becomes equal to or greater than the predetermined definite value Cop_fix, it is determined that the load circuit of the load circuit is abnormal. To do.
Accordingly, when the cause of the voltage drop abnormality is not the load circuit short circuit abnormality, it is possible to further determine whether the load circuit is a power line disconnection abnormality or an instantaneous voltage drop.

(3) The abnormality determination unit 80 stops driving the load circuit 50 when it is determined that the load circuit is short-circuited or the power line is disconnected. Further, the abnormality determination unit 80 determines that the signal circuit voltage change amount ΔV _SC is less than the change amount threshold ΔV _SC _th and that the update value of the load circuit voltage V _LC is normal before the power supply line disconnection abnormality determination of the load circuit is confirmed. When the return determination threshold value V _LC _re_th or more is restored, the drive of the load circuit 50 is continued.
In the case of a short circuit abnormality in the load circuit or a power line disconnection abnormality, the system can be prevented from being broken by stopping the system. On the other hand, in the case of instantaneous voltage drop, unnecessary system stop can be avoided and system operation can be maintained.

(4) The abnormality determination unit 80 further acquires the updated value of the signal circuit voltage V _SC while repeatedly acquiring the updated value of the load circuit voltage V _LC until the determination of the power supply line disconnection abnormality of the load circuit is confirmed. Then, to implement the short abnormality determination of the load circuit by comparing the signal circuit voltage variation [Delta] V _SC based on the updated value of the signal circuit voltage V _SC and the change amount threshold value [Delta] V _SC - th.
Accordingly, when a short circuit abnormality occurs during the power line disconnection abnormality confirmation waiting time of the load circuit, it is possible to determine the short circuit abnormality and prevent system breakdown.

(5) The microcomputer 43 further includes a pre-abnormality detection voltage calculation unit 70 that calculates the pre-abnormality detection signal circuit voltage value V _SC _tr_pd that can be used by the malfunction determination unit 80 for abnormality determination.
Accordingly, the abnormality determination section 80 may be abnormality determination using an appropriate abnormality detection before the signal circuit voltage V _SC _tr_pd.

(6) The voltage detection unit before abnormality detection 70, after the judgment time X [ms] has elapsed since the voltage buffer was started, the voltage buffer value V _SC _tr_pd_bf (X [ms] before the judgment time X [ms] from the present ] Before) is used as the signal circuit voltage value before abnormality detection V _SC _tr_pd.
As a result, it is possible to avoid the use of the signal circuit voltage value V _SC _tr_pd when the load circuit voltage V _LC is decreasing in accordance with the decrease in the load circuit voltage V _LC , and prevent erroneous determination.

(7) The pre-abnormality detection voltage calculation unit 70 starts buffering the signal circuit voltage V _SC _tr_pd after the power-on duration Tsys_on from the start of power supply by the battery 10 reaches the voltage stabilization waiting time Tsys_th.
This makes it possible to avoid the use of the signal circuit voltage value V _SC when the system voltage is not stable and prevent erroneous determination.

(8) fault detection before voltage calculation unit 70, except when the abnormality detection before the signal circuit voltage V _SC _tr_pd are usable voltage buffer value V _SC _tr_pd_bf, the abnormality detection before the signal circuit voltage default values V _SC _def Used as the value V _SC _tr_pd.
By using the default value V _SC _def that is set so that the abnormality determination unit 80 determines that there is a load circuit short-circuit abnormality, it is possible to avoid detection omission of the load circuit short-circuit abnormality by making a safe determination. It is possible to prevent destruction.

(Second embodiment)
The power supply voltage abnormality determination device of the second embodiment will be described with reference to FIGS. 11 to 13. In FIG. 11, the same components as those in FIG. 2 of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
In the second embodiment, a plurality of voltage values are input to the microcomputer 43 for at least one of the load circuit voltage V _{LC and the} signal circuit voltage V _SC . In the example of FIG. 11, a plurality of load circuit voltage values V _LC [0], V _LC [1], ..., V _LC [N-1] and a plurality of signal circuit voltage values V _SC [0], V _SC [1], ..., V _SC [N-1] are input to the microcomputer 43.

As an assumed system configuration, for example, assuming that a voltage drop abnormality of one of the load circuits affects the entire system, a plurality of load circuits are provided, the voltage value of each load circuit, and the corresponding A system in which a microcomputer monitors the voltage value of each signal circuit is conceivable.
Alternatively, in a system having a plurality of load circuit power supply lines connected to one load circuit, or a system having a plurality of signal circuit power supply lines connected to one signal circuit, the voltage value of each power supply line is set by a microcomputer. It can also be applied to systems monitored by.

  The microcomputer 43 has a multiple input voltage processing unit 90 including a load circuit voltage value selection unit 91, a signal circuit voltage value selection unit 92, and a pre-abnormality detection buffer signal circuit voltage value selection unit 93. Each selection unit 91, 92, 93 of the multiple input voltage processing unit 90 calculates and outputs a voltage selection value based on the multiple input voltage values.

The load circuit voltage value selection unit 91 outputs the load circuit voltage selection value V _LC _sel to the load circuit voltage drop determination unit 61, the load circuit short circuit determination unit 82, and the load circuit disconnection determination unit 83. The signal circuit voltage value selection unit 92 outputs the signal circuit voltage selection value V _SC _sel to the load circuit short circuit determination unit 82. The pre-abnormality detection signal circuit voltage value selection unit 93 outputs the buffering signal circuit voltage selection value V _SC _bf_sel to the pre-abnormality voltage buffer calculation unit 72.
The configuration of the microcomputer 43 other than that shown in FIG. 11 is similar to that of FIG. Further, the processing of the microcomputer 43 after each voltage selection value is input is the same as that of the first embodiment.

The interpretation of the term "selection" in each selection unit 91, 92, 93 will be described.
The “selection” includes extracting any one of the plurality of input voltage values, for example, the maximum value or the minimum value as a representative value. Further, the “selection” includes calculating an average value by a simple average or a weighted average, other function values, a map reference value, etc., based on a plurality of input voltage values. Further, "selection" includes performing a majority decision process based on the distribution of a plurality of input voltage values.
In the following description of the specific example of selection, the load circuit voltage V _LC and the signal circuit voltage V _SC are not distinguished and are collectively referred to as the “input voltage value V _IN ”. Further, the number of input interfaces of the input voltage value V _IN is “N (≧ 2)”, and a variable that takes an integer value from 1 to N is represented as “n”.

FIG. 12 shows a flowchart of the majority voting process.
In S61 to S65, the N input voltage values V _IN are sequentially compared with the voltage threshold Vth, and the number of input voltage values V _IN equal to or higher than the voltage threshold Vth is counted.
In S61, the initial value of the variable n is set to 0. When the variable n is from 0 to (N-1), YES is determined in S62, and the process proceeds to the determination step of S63. When the n-th input voltage value V _IN [n] is equal to or higher than the voltage threshold Vth, YES is determined in S63, and the majority count value Cmv is incremented in S64. Next, in S65, the variable n is moved to the next value. This loop is repeated until the variable n reaches the number of inputs N and NO is determined in S62.

In S66, it is determined whether or not the majority vote count value Cmv is a majority of the input number.
When the majority count value Cmv is a majority, it is determined as YES in S66, and the majority voltage value Vmv is set as the voltage threshold Vth in S67. On the other hand, when the majority count value Cmv is less than half, it is determined as NO in S66, and the majority voltage value Vmv is set to 0 in S68.
In this method, the binary value of the voltage threshold value Vth or 0 is alternatively selected as the selected value. Further, if the determination in S66 is changed to “Cmv = N?”, It is possible to determine the total match.

FIG. 13 shows a flowchart of (a) minimum value, (b) maximum value, and (c) average value calculation.
The meaning of each symbol is as follows.
V _MIN : Minimum voltage value, MIN (): Minimum value selection function V _MAX : Maximum voltage value, MAX (): Maximum value selection function V _AVE : Average voltage value, AVE (): Average value selection function

In S7A of FIG. 13A, the minimum value V _MIN of N input voltage values V _IN [0], V _IN [1], V _IN [2], ..., V _IN [N−1] is It is calculated as a selected value.
In S7B of FIG. 13B, the maximum value V _MAX of N input voltage values V _IN [0], V _IN [1], V _IN [2], ..., V _IN [N−1] is obtained. It is calculated as a selected value.
In S7C of FIG. 13C, the average value V _AVE of the N input voltage values V _IN [0], V _IN [1], V _IN [2], ..., V _IN [N−1] is It is calculated as a selected value.

  In the second embodiment, in a system in which a plurality of voltage values are input to the microcomputer 43, the method of calculating a selection value based on a plurality of input voltage values can be changed according to needs. For example, in a system that prioritizes fail-safe when a voltage drop abnormality occurs, the voltage value may be selected so that the ECU power-off treatment can be easily performed based on the abnormality determination. On the other hand, in a system that prioritizes the securing of system functions, the voltage value may be selected so that it is easy to continue the operation.

(Other embodiments)
(A) In the configuration of FIG. 1, the voltage of the battery 10 is directly input to the signal circuit connector 31 and the load circuit connector 36. However, a DCDC converter or the like may be provided between the battery 10 and the connectors 31 and 36 so that the transformed voltage is input to the connectors 31 and 36. If the system uses the same power supply voltage of the DC power supply as the load circuit voltage V _LC and the signal circuit voltage V _SC in common, the configuration of the present invention is established.

(B) In the configuration of FIG. 2, the microcomputer 43 configures the ECU 30 together with the load drive circuit 54 and the like. However, the ECU 30 may not be configured as a control unit, and independent signal circuits 40 and load circuits 50 may be electrically connected.
(C) In a system in which the signal circuit voltage value V _SC before abnormality detection is always stable to the extent that it can be used for the determination of the abnormality determination unit 80, the pre-abnormality detection voltage calculation unit 70 may not be provided.

(D) In a system in which there is almost no possibility of a disconnection abnormality between the battery 10 and the monitoring point 53, only a short circuit abnormality of the load circuit may be determined as the cause of the voltage drop abnormality.
(E) You may set "once" as the abnormality determination fixed value Ctr_fix of FIG. 3 and the disconnection abnormality fixed value Cop_fix of FIG. In that case, the abnormality can be confirmed at the stage of the first abnormality determination.

(F) The load of the ECU in the electric power steering device may be an H bridge circuit and a DC motor instead of the inverter and the AC motor. Further, the power supply voltage abnormality determination device of the present invention is not limited to a motor drive device such as an electric power steering device, but is applied to any load drive system in which a power supply voltage is applied to a load circuit and a signal circuit from the same power supply. May be.
As described above, the present invention is not limited to the above-described embodiment and can be implemented in various forms without departing from the spirit of the invention.

10 ... Battery (DC power supply),
40 ... Signal circuit,
43 ... Microcomputer (power supply voltage abnormality determination device),
50 ... Load circuit,
60 ... (load circuit voltage drop) abnormality detection unit,
70 ... Voltage calculation unit before abnormality detection (signal circuit),
80 ... (Load circuit voltage drop) abnormality determination unit.

Claims (9)

In a load driving system in which a power supply voltage is applied to the load circuit (50) and the signal circuit (40) from the same DC power supply (10), a load circuit voltage (V _LC ) which is a power supply voltage applied to the load circuit, And a power supply voltage abnormality determining device for monitoring a signal circuit voltage (V _SC ) which is a power supply voltage applied to the signal circuit,
An abnormality detection unit (60) for detecting an abnormality in the reduced state of the load circuit voltage when the value of the load circuit voltage falls below a voltage reduction determination threshold value (V _LC th);
When an abnormality of the load circuit voltage drop state is detected, a signal circuit voltage change amount (which is a difference between the signal circuit voltage value (V _SC _tr_pd) before the abnormality detection and the signal circuit voltage value after the abnormality detection ( ΔV _SC ), if the signal circuit voltage change amount is equal to or more than the change amount threshold value (ΔV _SC _th), it is determined that the load circuit has a short circuit abnormality, and the signal circuit voltage change amount is less than the change amount threshold value. An abnormality determination unit (80) for determining that the power supply line of the load circuit is abnormal, or an instantaneous voltage drop,
A power supply voltage abnormality determination device including. The abnormality determination unit,
When the signal circuit voltage change amount is less than the change amount threshold value, the load circuit voltage value is further compared with a normal recovery determination threshold value (V _LC re_th), and the update value of the load circuit voltage is less than the normal recovery determination threshold value. The power supply voltage abnormality determination device according to claim 1, wherein when the number of times (Cop) determined to be equal to or more than a predetermined definite value (Cop_fix) is determined, it is determined that there is a power supply line disconnection abnormality of the load circuit. The abnormality determination unit,
When it is determined that there is a short circuit abnormality of the load circuit or a power line disconnection abnormality, the drive of the load circuit is stopped,
When the change amount of the signal circuit voltage is less than the change amount threshold value, and when the update value of the load circuit voltage returns to the normal return determination threshold value or more before the power line disconnection abnormality determination of the load circuit is confirmed, The power supply voltage abnormality determination device according to claim 2, wherein the drive of the load circuit is continued. The abnormality determination unit,
While repeatedly acquiring the update value of the load circuit voltage until the determination of the power line disconnection abnormality of the load circuit is confirmed, the update value of the signal circuit voltage is further acquired, and based on the update value of the signal circuit voltage. The power supply voltage abnormality determination device according to claim 2, wherein a short circuit abnormality determination of the load circuit is performed by comparing the signal circuit voltage variation amount with the variation amount threshold value.   The power supply voltage according to any one of claims 1 to 4, further comprising a pre-abnormality detection voltage calculation unit (70) for calculating the signal circuit voltage value before the abnormality detection that can be used by the abnormality determination unit for abnormality detection. Anomaly judgment device. The voltage calculation unit before abnormality detection,
After a predetermined voltage buffer use permission determination time (X [ms]) has elapsed since the buffer of the signal circuit voltage was started, the buffer value (V of the signal circuit voltage before the voltage buffer use permission determination time from the present) _{SC _tr_pd_bf} (X [ms] ago)) supply voltage abnormality determination apparatus according to claim 5 for use as a signal circuit a voltage value before the abnormality detecting. The voltage calculation unit before abnormality detection,
The power supply voltage abnormality determination device according to claim 6, wherein after the power-on duration (Tsys_on) from the start of power supply by the DC power supply reaches a voltage stabilization wait time (Tsys_th), the buffer of the signal circuit voltage is started. . The voltage calculation unit before abnormality detection,
A default value set to be determined as a short circuit abnormality of the load circuit in the abnormality determination unit, except when the buffer value of the signal circuit voltage can be used as the signal circuit voltage value before the abnormality detection. The power supply voltage abnormality determination device according to claim 6, wherein (V _SC def) is used as the signal circuit voltage value before the abnormality detection. At least one of the load circuit voltage or the signal circuit voltage, a power supply voltage abnormality determination device to which a plurality of voltage values are input,
A plurality of selection values of the load circuit voltage or the signal circuit voltage are calculated based on a plurality of input voltage values (V _IN [0], V _IN [1], ..., V _IN [N-1]). The power supply voltage abnormality determination device according to claim 1, further comprising an input voltage processing unit (90).

Images