JP5541189B2 - Current sensor abnormality determination device - Google Patents

Description

  The present invention relates to an apparatus for determining an abnormality of a current sensor that detects a battery current when a vehicle-mounted battery is charged and discharged.

  2. Description of the Related Art Conventionally, a technique for providing a current sensor for detecting a battery current when a battery is charged / discharged and controlling the operation of a generator and the like so as to optimize the state of charge of the battery based on the value of the current sensor is known. Yes. Patent Document 1 describes an apparatus for determining whether or not the current sensor is abnormal as follows. That is, when the generator mounted on the vehicle starts regenerative power generation, the battery current value increases rapidly with regenerative charging. Therefore, if the detection value of the current sensor at the start of regenerative power generation does not change by a predetermined value or more, it is determined that the current sensor is abnormal.

JP 2007-51943 A

  However, in the above-described conventional apparatus, since abnormality of the current sensor can be determined only when regenerative power generation is started, it has been desired to increase the chance of abnormality determination.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a current sensor abnormality determination device that increases opportunities for abnormality determination.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In the first invention, a generator mounted on a vehicle, a battery that charges electric power generated by the generator and discharges to an electric load mounted on the vehicle, and a battery current that flows through the battery when charging and discharging. It is assumed that the present invention is applied to a vehicle power supply system including a current sensor for detecting the

  And a charging determination unit that determines whether or not the battery is being charged, and an absolute value of a detection value of the current sensor when the charging determination unit determines that the battery is charging. A charging abnormality determining unit that determines that the current sensor is abnormal if the threshold is equal to or greater than a threshold, and the charging threshold is output from the generator when the generator is operating at a maximum output. It is characterized in that it is set based on the maximum power generation current value that is the value of the current to be generated.

  The maximum generated current value, which is the current value when the generator is operating at maximum output, is determined from the performance of the generator. Therefore, the current value that flows into the battery during charging should not exceed the maximum power generation current value. Therefore, if the detection value of the current sensor exceeds the maximum power generation current value, it can be said that there is a high probability that the current sensor is abnormal.

  In the above invention in view of this point, a charging threshold is set based on the maximum power generation current value when the generator is operating at the maximum output, and the absolute value of the detection value of the current sensor is charged during charging. If it is equal to or greater than the hour threshold, it is determined to be abnormal. Therefore, since abnormality of the current sensor can be determined during charging, the chance of abnormality determination can be increased as compared with the above-described conventional device that can determine abnormality only when regenerative power generation is started.

In a second aspect of the invention, the charging threshold is changed during vehicle operation so that the charging threshold is lowered as the power generation output level of the generator is lower.

  As the power generation output degree (corresponding to the horizontal axis “Fduty” in FIG. 6) is higher, the power generation maximum current of the generator (corresponding to the vertical axis “alter max current” in FIG. 6) also increases. Therefore, when the charging threshold is fixed and set contrary to the above invention, the charging threshold is set to the maximum power generation current value (about 150 A in the example of FIG. 6) when the Fduty is the maximum (100%). It is required to do. On the other hand, in the said invention, the threshold value at the time of charge is set low, so that the power generation output degree is low. Therefore, for example, in the case of FIG. 6, when the Fduty is less than 100% and the maximum power generation current value is less than 150A, the charging threshold is set to a value lower than 150A. Accuracy can be improved.

In a third aspect of the invention, when the charging abnormality determination unit determines that the charging determination unit determines that charging is being performed and the positive or negative value of the detection value of the current sensor is a value on the discharge side, the current sensor is It is determined to be abnormal.

  For example, in a current sensor provided to detect a detection value during charging with a positive value, if the detection value during charging is a negative value, it can be said that there is a high probability that the current sensor is abnormal. Therefore, in the above invention, since the abnormality is determined when the positive / negative of the detection value at the time of charging is a value on the discharge side, the accuracy of the abnormality determination can be improved.

In a fourth aspect of the invention, the plurality of electric loads mounted on the vehicle includes a constant voltage required electric load that is applied by boosting the voltage of the discharge power of the battery with a booster circuit. In the case of having a current detection circuit for detecting its own output current value, the charging threshold value is set based on a value obtained by subtracting the detected current value by the current detection circuit from the maximum generated current value. It is characterized by that.

  By the way, among the electric loads mounted on the vehicle, there is a problem that the operation content of the device is reset when the voltage of the supplied power is lower than a predetermined value, such as a navigation device or an audio device. In particular, since a large current is required to drive the starter motor of the internal combustion engine, when the internal combustion engine is started, the above-described device (constant voltage required electric load) is reset as the battery voltage temporarily decreases greatly. There is a concern about the malfunction that will be done. Therefore, conventionally, a technique of boosting power by a booster circuit (DCDC converter) and supplying power to a constant voltage required electric load has been widely adopted. Many booster circuits have a current detection circuit for detecting their own output current value.

  The above invention pays attention to setting a threshold value at the time of charging using a current detection circuit included in such a booster circuit. That is, if a current (boosted current) is flowing into the constant voltage demand electric load, the current value flowing into the battery during charging should not exceed the value obtained by subtracting the boosted current from the maximum generated current. The boosted current can be detected by a current detection circuit. In the above invention in view of this point, the charging threshold is set based on the value obtained by subtracting the detected current value from the current detection circuit from the maximum generated current value, so that the charging threshold is set to a value smaller than the maximum generated current. Determination by the abnormality determination means at the time of charge can be implemented. Therefore, the determination accuracy by the charging abnormality determination unit can be improved.

In the fifth and sixth aspects of the invention, the discharge determination means for determining whether or not the battery is being discharged and the detection value of the current sensor when the discharge determination means determines that the battery is discharging A discharge abnormality determining unit that determines that the current sensor is abnormal if the absolute value is equal to or greater than a predetermined discharge threshold, wherein the discharge threshold is a plurality of the electric loads mounted on the vehicle. It is set based on the sum of the maximum current consumption values.

  The value of current flowing out of the battery during discharging should not exceed the sum of the maximum current consumption values (maximum current consumption values) of a plurality of electrical loads. Therefore, if the detection value of the current sensor exceeds the total of the maximum current consumption values, it can be said that there is a high probability that the current sensor is abnormal.

  In the above invention in view of this point, a discharge threshold value is set based on the total of the respective maximum current consumption values, and it is abnormal if the absolute value of the detection value of the current sensor is equal to or greater than the discharge threshold value during discharge. Judge that there is. For this reason, the abnormality of the current sensor can be determined during discharging, so that the chance of abnormality determination can be increased as compared with the above-described conventional apparatus in which the abnormality can be determined only at the start of regenerative power generation.

In a seventh aspect of the invention, when the discharge abnormality determination unit determines that the discharge determination unit determines that the discharge is being performed and the positive / negative value of the detection value of the current sensor is a charge side value, the current sensor It is determined to be abnormal.

  For example, in a current sensor provided to detect a detection value at the time of discharge with a negative value, if the detection value at the time of discharge is a positive value, it can be said that there is a high probability that the current sensor is abnormal. Therefore, in the above invention, since the abnormality is determined when the positive / negative of the detected value at the time of discharge is the value on the charging side, the accuracy of the abnormality determination can be improved.

In an eighth aspect of the invention, a constant voltage required electric load is applied to the plurality of electric loads mounted on the vehicle by boosting and applying the voltage of the discharge power of the battery by a boosting circuit, and without boosting by the boosting circuit. In the case where a general electric load to which discharge power is supplied is included, and the booster circuit has a current detection circuit that detects its own output current value, the threshold during discharge is the value of the general electric load. It is set based on a value obtained by adding a current value detected by the current detection circuit to a sum of maximum current consumption values.

  As described above, many booster circuits (DCDC converters) provided for constant voltage required electrical loads such as navigation devices and audio devices have current detection circuits for detecting their own output current values. Exists. The above invention pays attention to setting a threshold value at the time of discharge using a current detection circuit included in such a booster circuit.

  In other words, if the current (boosted current) is flowing into the constant voltage demand electric load, the current value that flows out of the battery during discharging is the sum of the maximum current consumption values of the general electric load plus the boost current. It should not exceed. The boosted current can be detected by a current detection circuit. In the above invention in view of this point, since the discharge threshold is set based on the sum of the maximum current consumption values of the general electric load and the detected current value by the current detection circuit, the general electric load and the constant voltage required electric load are set. It is possible to perform the determination by the discharge abnormality determining means while setting the discharge threshold value to a value smaller than the total of the maximum current consumption values. Therefore, the determination accuracy by the discharge abnormality determination unit can be improved.

In a ninth aspect of the invention, the discharge determination means determines whether or not the battery is discharging based on whether or not the power generator is stopped.

  If the generator is generating power, the battery may be in a discharged state or in a charged state. However, if power generation is stopped, the battery is reliably discharged. In the above-mentioned invention in view of this point, it is determined whether or not the discharge is being performed based on whether or not the power generation is stopped. An abnormality determination by means can be performed. Therefore, the possibility of erroneous determination by the discharge determination means can be eliminated, and consequently the accuracy of abnormality determination by the discharge abnormality determination means can be improved.

1 is a diagram illustrating a vehicle power supply system to which a current sensor abnormality determination device is applied in a first embodiment of the present invention. In 1st Embodiment, it is a figure explaining the method of detecting a disconnection short circuit abnormality with respect to a current sensor. (A) is a figure which shows the flow of an electric current when the battery is charged, (b) is a figure explaining the method of detecting characteristic abnormality at the time of battery charge. (A) is a figure which shows the flow of the electric current when the battery is discharging, (b) is a figure explaining the method of detecting characteristic abnormality at the time of battery discharge. 5 is a flowchart illustrating a procedure for determining a characteristic abnormality in the first embodiment. It is a graph which shows the result of the test which detected alternator max electric current when changing Fduty. It is a flowchart which shows the determination procedure of characteristic abnormality in 2nd Embodiment of this invention. In 3rd Embodiment of this invention, it is a figure which shows the vehicle power supply system with which a current sensor abnormality determination apparatus is applied. In 3rd Embodiment, it is a figure which shows the flow of an electric current when the battery is charged. In 3rd Embodiment, it is a figure which shows the flow of an electric current when the battery is discharging. 10 is a flowchart illustrating a procedure for determining a characteristic abnormality in the third embodiment.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
A vehicle on which the in-vehicle power supply device according to the present embodiment is mounted is a vehicle that uses an internal combustion engine as a travel drive source. When a predetermined automatic stop condition is satisfied, the internal combustion engine is automatically stopped, and a predetermined automatic restart condition is established. The engine has an idle stop function that automatically restarts the internal combustion engine when the condition is satisfied. In addition, although the starter motor which rotates a crankshaft at the time of the start of an internal combustion engine is mounted in the vehicle concerning this embodiment, the motor for driving which assists vehicle driving | running | working is not mounted.

  As shown in FIG. 1, the vehicle includes an alternator 10 (generator), a regulator 11 (power generation control means), a battery 20, various electric loads 31, 32, and an electronic control unit (ECU 40) described below. The electric loads 31 and 32 and the battery 20 are electrically connected to the alternator 10 in parallel.

  The electric power generated by the alternator 10 is supplied to the various electric loads 31 and 32 and is also supplied to the battery 20. When driving of the internal combustion engine is stopped and power generation by the alternator 10 is stopped, power is supplied from the battery 20 to the electric loads 31 and 32.

  Of the electric loads 31 and 32, a load indicated by reference numeral 31 is a starter motor that starts the internal combustion engine, and a load indicated by reference numeral 32 is a general electric load other than the starter motor 31. Specific examples of the general electric load 32 include a headlight, a wiper such as a front windshield, a blower fan for an air conditioner, and a defroster heater for a rear windshield.

The battery 20 is a well-known lead storage battery. Specifically, the positive electrode active material is lead dioxide (PbO ₂ ), the negative electrode active material is lead (Pb), and the electrolytic solution is sulfuric acid (H ₂ SO ₄ ). And the some battery cell comprised from these electrodes is connected in series, and is comprised.

  The alternator 10 generates electric power using the rotational energy of the crankshaft. Specifically, when the rotor of the alternator 10 is rotated by the crankshaft, an alternating current is induced in the stator coil according to the exciting current flowing through the rotor coil 10a, and is converted into a direct current by a rectifier (not shown). And the regulator 11 adjusts the exciting current which flows into the rotor coil 10a, and it adjusts so that the voltage (power generation voltage) of the direct current generated may become a target voltage (for example, 14V).

  In short, the regulator 11 functions to adjust the generated voltage stably to the target voltage even if the crankshaft rotational speed (engine rotational speed NE) and the power consumption of the electric loads 31 and 32 fluctuate. For example, as the power consumption of the electric loads 31 and 32 is larger or the NE is lower, the exciting current flowing through the rotor coil 10a is increased so as to maintain the generated voltage at the target voltage. On the other hand, the smaller the power consumption of the electric loads 31, 32, or the higher the NE, the smaller the exciting current that flows to the rotor coil 10a in order to maintain the generated voltage at the target voltage.

  The excitation current is adjusted by duty control, and the excitation current becomes maximum when the duty ratio is 100%. Therefore, the duty ratio is 100% because the power generation amount is insufficient with respect to the power consumption of the electric loads 31 and 32 even though the alternator 10 is generating power at the maximum output. Yes, the generated voltage is lower than the target voltage. Therefore, when the duty ratio is 100%, the battery 20 is not charged. When the duty ratio is less than 100%, it can be said that the battery 20 is being charged.

  The voltage sensor 41 shown in FIG. 1 detects the terminal voltage (battery voltage) of the battery 20. Incidentally, since the battery 20 is connected in parallel with the alternator 10, the battery voltage detected by the voltage sensor 41 matches the voltage (power generation voltage) on the output side of the alternator 10. The current sensor 42 shown in FIG. 1 detects a battery current that flows into the battery 20 when the battery 20 is charged, and a battery current that flows out of the battery 20 when the battery 20 is discharged. The current sensor 42 according to the present embodiment detects a battery current during charging with a positive value and a battery current during discharging with a negative value.

  The ECU 40 calculates the SOC (State of charge) of the battery 20 based on the detected values of the voltage sensor 41 and the current sensor 42. When the SOC is out of the proper range and is in an overdischarge or overcharge state, the battery 20 is rapidly deteriorated. Therefore, the ECU 40 controls the operation of the regulator 11 so as to reduce the target voltage (power generation voltage) and suppress the charging of the battery 20 when the calculated SOC is out of the proper range and is overcharged. . On the other hand, in the case of overdischarge, the operation of the regulator 11 is controlled so as to increase the target voltage (generated voltage) and promote the charging of the battery 20.

  Moreover, in this embodiment, the deceleration regeneration which makes the alternator 10 generate electric power with the regeneration energy of a vehicle and charges the battery 20 is performed. This deceleration regeneration is performed when a condition such as that the vehicle is in a decelerating state or that the fuel injection to the internal combustion engine is cut is satisfied. In this way, when performing deceleration regeneration, the target voltage may be raised to increase the amount of recovered regenerative energy.

  As described above, the detected value of the current sensor 42 is used for the ECU 40 to control the SOC of the battery 20 to be within an appropriate range. Therefore, detecting an abnormality of the current sensor 42 is important for avoiding early deterioration of the battery 20. Therefore, in the present embodiment, the disconnection or short circuit abnormality detection is performed for the current sensor 42, and the characteristic abnormality in which the characteristic of the current sensor 42 changes beyond the limit due to aging deterioration is detected.

  FIG. 2 is a diagram for explaining a detection method of a disconnection / short circuit abnormality. In FIG. 2, the vertical axis represents the output value of the current sensor 42 and is converted into a range of 0 V to 5 V that can be processed by the microcomputer. Indicates the value of. However, 0.5V to 4.5V is set as the current value detection range, the lowest detectable current (−300A) corresponds to 0.5V, and the highest detectable current (+ 100A) is 4.5V. It corresponds to.

  Therefore, when the signal line connecting the current sensor 42 and the ECU 40 or the signal line inside the current sensor 42 is disconnected, the output value of the current sensor 42 becomes higher than the detection range. Therefore, when the output value of the current sensor 42 exceeds 4.5V or becomes 5V, the ECU 40 determines that the disconnection is abnormal. Further, when the current sensor 42 is grounded, the output value of the current sensor 42 becomes lower than the detection range. Therefore, when the output value of the current sensor 42 becomes lower than 0.5V or becomes 0V, the ECU 40 determines that the short circuit is abnormal.

  By the way, even if the output value of the current sensor 42 is within the detection range, the output value is offset when the output value is offset from the actually flowing current value or when the output gain changes over time. May have deteriorated over time. Hereinafter, a method for detecting such an abnormality of aging will be described with reference to FIGS.

  FIG. 3A is a diagram showing the flow of current when the battery 20 is charged, the current of the generated power output from the alternator 10 being the generated current IALT, the current flowing into the battery 20 being the battery current IB, Currents flowing into each of the plurality of electric loads 32 are represented as load currents I1 and I2. The relationship between these current values is IALT = IB + I1 + I2 according to Kirchhoff's law.

  Therefore, the battery current IB becomes maximum when the generated current IALT is maximum and the load currents I1 and I2 are zero. In other words, during charging, the battery current IB should not increase beyond the maximum value (alter max current) of the generated current IALT. In addition, the battery current IB should not be negative during charging. That is, if the current sensor 42 is normal, the detected value of the battery current IB should fall within the range of 0 A to alternator max current.

  In view of this point, in this embodiment, the value of the alternator max current (maximum power generation current value) is set to the charging threshold THin, and the detected value of the current sensor 42 exceeds the charging threshold THin during charging. If it is larger or a negative value, it is determined that the characteristic is abnormal (see FIG. 3B).

  FIG. 4A is a diagram showing a current flow when the battery 20 is discharged. At this time, the generated current IALT is zero, the battery current IB detected by the current sensor 42 is a negative value, and −IB = I1 + I2 according to Kirchhoff's law.

  Therefore, the battery current IB becomes minimum (the absolute value of IB is maximum) when all of the plurality of electric loads 32 are driven by the maximum load, and the sum of the maximum consumption currents of the respective electric loads 32 ( Consumption max current) is the minimum value of the battery current IB. In other words, at the time of discharging, the battery current IB should not decrease beyond the sum of the maximum current consumption of the electric load 32 (maximum current consumption). In addition, the battery current IB should not be positive during discharging. That is, if the current sensor 42 is normal, the detected value of the battery current IB should fall within the range of the consumed max current to 0A.

  In the present embodiment in view of this point, the value of the consumed max current is set to the discharge threshold THout, and when the value detected by the current sensor 42 is smaller than the discharge threshold THout during discharge, Alternatively, when the value is positive, it is determined that the characteristic is abnormal (see FIG. 4B).

  FIG. 5 is a flowchart showing a procedure for performing the above-described characteristic abnormality determination, and this process is repeatedly executed at a predetermined cycle by the microcomputer of the ECU 40. This process is executed on condition that the above-described disconnection short circuit abnormality is not detected.

  First, in steps S10 (discharge determination means) and S20 (charge determination means) shown in FIG. 5, it is determined whether the battery 20 is being charged or discharged. Specifically, if the engine is in an idle stop (S10: YES), it is determined that the battery is being discharged. Further, when the engine is not idling stop (S10: NO), if the power generation output degree Fduty described above is not 100% (S20: YES), it is determined that charging is in progress. Even when the idle stop is not being performed (S10: NO), if the Fduty is 100% (S20: NO), the generated voltage is lower than the target voltage as described above. It is determined that the battery is being discharged.

  If it is determined that charging is in progress, the process proceeds to step S30, and the value of the charging threshold THin used for the deterioration abnormality determination is set based on the power generation output degree Fduty. FIG. 6 is a graph showing the results of a test in which the alternator max current is detected when Fduty is changed, and shows that the alternator max current decreases as Fduty decreases. In this test, the engine speed NE is kept constant, and the ambient temperature is changed to minus 30 ° C., 25 ° C., and 90 ° C. for testing. Solid lines L1, L2, and L3 indicate the relationship between Fduty and alternator max current at −30 ° C., 25 ° C., and 90 ° C., respectively.

  In step S30, the charging threshold THin is set based on the alternator max current at −30 ° C. That is, for example, when Fduty is 100%, THin = 150A is set according to the solid line L1. For example, when Fduty is 20%, THin = 30A is set according to the solid line L1.

  In subsequent step S40 (charging abnormality determination means), the determination of FIG. That is, it is determined whether or not the value of the battery current IB detected by the current sensor 42 is within the range of 0A to the charging threshold THin. When it determines with it being in the said range (S40: YES), it determines with the current sensor 42 being normal in subsequent step S50. On the other hand, if it is determined that it is not within the range (S40: NO), it is determined in the subsequent step S60 that the current sensor 42 is abnormal in characteristics.

  If it is determined in steps S10 and S20 that the battery is being discharged, the process proceeds to step S70 (discharge abnormality determining means) and the determination shown in FIG. That is, it is determined whether or not the value of the battery current IB detected by the current sensor 42 is within the range of the discharge threshold value THout to 0A. When it determines with it being in the said range (S70: YES), it determines with the electric current sensor 42 being normal in subsequent step S50. On the other hand, if it is determined that it is not within the range (S70: NO), it is determined in the subsequent step S60 that the current sensor 42 is abnormal in characteristics.

  As described above, according to the present embodiment, it is possible to determine the characteristic abnormality of the current sensor 42 during charging and discharging. Therefore, the chance of characteristic abnormality determination can be increased as compared with the conventional device described in Patent Document 1 described above, which can determine abnormality only at the start of regenerative power generation.

  Further, since the charging threshold THin is set lower as the power generation output degree Fduty is lower, it is possible to prevent the range used for the determination in step S40 of FIG. Can be improved.

(Second Embodiment)
In the first embodiment, whether the battery 20 is being charged or discharged is determined depending on whether or not there is a characteristic abnormality. In the present embodiment shown in FIG. The presence / absence of characteristic abnormality is determined without performing case classification. In FIG. 7, the same reference numerals as those in FIG. The hardware configuration of the vehicle power supply system in the present embodiment is the same as that in the first embodiment shown in FIG.

  First, in step S30 in FIG. 7, a charging threshold THin is set based on the power generation output degree Fduty. Since Fduty = 0% when power generation is stopped, the charging threshold THin is set to zero.

  In a succeeding step S45, it is determined whether or not the value of the battery current IB detected by the current sensor 42 is within a range from the discharge threshold THout to the charge threshold THin. When it determines with it being in the said range (S45: YES), it determines with the current sensor 42 being normal in subsequent step S50. On the other hand, when it is determined that it is not within the above range (S45: NO), it is determined in the subsequent step S60 that the current sensor 42 is abnormal in characteristics.

  As described above, according to the present embodiment as well, it is possible to determine the characteristic abnormality of the current sensor 42 during charging or discharging, so it is possible to increase the chance of characteristic abnormality determination. However, although an abnormality in which the detection value of the current sensor 42 is negative during power generation and an abnormality in which the detection value of the current sensor 42 is positive during discharge can be detected in the first embodiment, in this embodiment, It cannot be detected.

(Third embodiment)
In the present embodiment shown in FIG. 8, a vehicle on which a constant voltage required electrical load 33 described below is mounted is an object. Specific examples of the constant voltage requesting electric load 33 include a navigation device and an audio. However, the electric load 33 has a problem that the operation content of the device is reset when the voltage of the supplied power drops below a predetermined value. Occurs. In particular, since a large current is required to drive the starter motor 31, a large current flows into the starter motor 31 when the internal combustion engine is started, and the battery voltage is temporarily greatly reduced. Then, there is a concern that the constant voltage request electric load 33 is reset.

  Therefore, in this embodiment, the discharged power of the battery 20 or the generated power of the alternator 10 is boosted by the DCDC converter 50 (boost circuit) and supplied to the electric load 33. The DCDC converter 50 includes a current detection circuit 51 that detects its own output current value. For example, the DCDC converter 50 performs boost control using the detection value of the current detection circuit 51.

  In the present embodiment, the characteristic abnormality determination is set as follows using the detection value of the current detection circuit 51 of the DCDC converter 50 as described above. Specifically, the DCDC converter 50 and the ECU 40 are connected by a communication line, and the detection value of the current detection circuit 51 is input to the ECU 40. The ECU 40 sets the charging threshold THin and the discharging threshold THout in consideration of the detection value of the current detection circuit 51. This setting method will be described below with reference to FIGS. 9 and 10.

  FIG. 9 is a diagram showing the flow of current when the battery 20 is charged. The current flowing into each of the general electric loads 32 is represented as load currents I1 and I2 and flows into each of the constant voltage requesting electric loads 33. The current is expressed as load currents I3 and I4. The current flowing through the DCDC converter 50, that is, the detection value of the current detection circuit 51 is represented as IDC. A relationship of IALT = IB + I1 + I2 + I3 + I4 and a relationship of IDC = I3 + I4 are established.

  Here, according to the method of FIG. 3 according to the first embodiment, “the battery current IB becomes maximum when the generated current IALT is maximum and the load currents I1, I2, I3, and I4 are zero. Based on the idea that the battery current IB should not increase beyond the maximum value (alter max current) of the generated current IALT, the characteristic abnormality is determined.

  However, in the present embodiment, since the current value of I3 + I4 (detection value IDC) can be acquired by the current detection circuit 51, “the battery current IB does not increase beyond the value obtained by subtracting the detection value IDC from the alternator max current. Characteristic abnormality can be determined according to the idea of “is.” That is, if the current sensor 42 is normal, the detected value of the battery current IB should fall within the range of 0A to alternator max current-IDC.

  In view of this point, in the present embodiment, a value obtained by subtracting the current detection value IDC from the DCDC converter 50 from the value of the alternator max current is set as the charging threshold THin, and the detection value of the current sensor 42 is charged during charging. When the charging threshold value THin is exceeded, it can be determined that the characteristic is abnormal.

  FIG. 10 is a diagram showing the flow of current when the battery 20 is discharging. In this case, the detected value (battery current IB) of the current sensor 42 is a negative value, and the relationship is −IB = I1 + I2 + I3 + I4. , And IDC = I3 + I4.

  Here, according to the method of FIG. 4 according to the first embodiment, “the battery current IB is minimized because the plurality of general electric loads 32 and the constant voltage required electric loads 33 are all driven at the maximum load. Characteristic abnormality is determined based on the idea that “battery current IB should not decrease beyond the sum of the maximum current consumption (maximum current consumption) of electric loads 32 and 33” based on the idea that Will be.

  However, in the present embodiment, the current value of I3 + I4 (detection value IDC) can be acquired by the current detection circuit 51, so that “the battery exceeds the value obtained by adding the detection value IDC to the total of the maximum current consumption of the general electric load 32. Characteristic abnormality can be determined according to the idea that the current IB should not be small. That is, if the current sensor 42 is normal, the detected value of the battery current IB should be within the range of the sum of the maximum current consumption of the general electric load 32 + IDC to 0A.

  In view of this point, in the present embodiment, a value obtained by adding the current detection value IDC by the DCDC converter 50 to the sum of the maximum current consumption (IRmax) of the general electric load 32 is set as the discharge threshold THout. When the detection value of the current sensor 42 is smaller than the discharge threshold THout, it can be determined that the characteristic is abnormal.

  FIG. 11 is a flowchart showing a procedure of characteristic abnormality determination according to the present embodiment, and the difference from FIG. 5 will be mainly described. In this embodiment, instead of step S30 in FIG. 5 in which the charging threshold THin is set based on Fduty, the charging threshold THin is set in step S31 based on the current detection value IDC and Fduty by the DCDC converter 50. That is, the charging threshold THin is set to a value obtained by subtracting IDC from the alternator max current corresponding to Fduty shown in FIG.

  Further, in the present embodiment, step S35 is added, and the discharge threshold value THout is set based on the current detection value IDC by the DCDC converter 50. That is, the discharge threshold value THout is set to a value obtained by adding IDC to the total maximum current consumption (IRmax) of the general electric load 32.

  As described above, according to the present embodiment as well, it is possible to determine the characteristic abnormality of the current sensor 42 during charging or discharging, so it is possible to increase the chance of characteristic abnormality determination. Moreover, since the charging threshold THin and the discharging threshold THout are set in consideration of the current detection value IDC by the DCDC converter 50, the charging threshold THin can be made small and the discharging threshold THout can be made large. That is, the range used for determining the characteristic abnormality can be narrowed so as to be close to the range of detection values that the normal current sensor 42 can take. Therefore, it is possible to improve the accuracy of determining the characteristic abnormality of the current sensor 42.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In each of the above embodiments, the charging time threshold THin is set based on the alternator max current value (power generation maximum current value) that varies depending on the power generation output degree Fduty. On the other hand, the charging threshold THin may be set based on the alternator max current value (power generation maximum current value) when the duty ratio is 100% regardless of the change in Fduty. That is, in the example of FIG. 6, the charging threshold THin is fixed to 150A.

  According to this, although the characteristic abnormality determination accuracy is lowered, the processing threshold for characteristic abnormality determination can be reduced because the charging threshold THin is fixed.

  In each of the above embodiments, the value of the threshold value THin during charging is changed based on the power generation output degree Fduty. However, the value of the alternator max current also changes depending on the engine speed NE and the ambient temperature. You may make it change the value of threshold value THin at the time of charge based on NE or temperature.

DESCRIPTION OF SYMBOLS 10 ... Alternator (generator), 32 ... General electric load, 33 ... Constant voltage request | requirement electric load, 42 ... Current sensor, 50 ... DCDC converter (boost circuit), 51 ... Current detection circuit, Fduty ... Power generation output degree, S10 ... , S20: Charge determination means, S40: Charge abnormality determination means, S70: Discharge abnormality determination means, THin: Charge threshold, THout: Discharge threshold.

Claims (9)

A generator mounted on the vehicle; a battery that charges the generated power by the generator and discharges to an electric load mounted on the vehicle; and a current sensor that detects a battery current flowing through the battery when charging and discharging. Applied to a vehicle power supply system comprising
Charging determination means for determining whether or not the battery is being charged;
When it is determined by the charging determination means that charging is in progress, if the absolute value of the detected value of the current sensor exceeds a predetermined charging threshold, it is determined that the current sensor is abnormal. An abnormality determination means during charging;
With
The charging threshold is set based on a power generation maximum current value that is a value of a current output from the generator when the generator is operating at a maximum output ,
The current sensor abnormality determination device, wherein the charging threshold value is changed during vehicle operation so that the charging threshold value is lowered as the power generation output level of the generator is lower. A generator mounted on the vehicle; a battery that charges the generated power by the generator and discharges to an electric load mounted on the vehicle; and a current sensor that detects a battery current flowing through the battery when charging and discharging. Applied to a vehicle power supply system comprising
Charging determination means for determining whether or not the battery is being charged;
When it is determined by the charging determination means that charging is in progress, if the absolute value of the detected value of the current sensor exceeds a predetermined charging threshold, it is determined that the current sensor is abnormal. An abnormality determination means during charging;
With
The charging threshold is set based on a power generation maximum current value that is a value of a current output from the generator when the generator is operating at a maximum output,
The plurality of electric loads mounted on the vehicle includes a constant voltage required electric load that is applied by boosting the voltage of the discharge power of the battery by a boosting circuit,
In the case where the booster circuit has a current detection circuit that detects its own output current value,
The charging threshold value is set based on a value obtained by subtracting a current value detected by the current detection circuit from the power generation maximum current value. 3. The current sensor abnormality determination device according to claim 2 , wherein the threshold value at the time of charging is changed during vehicle operation so that the threshold value at the time of charging is lowered as the power generation output level of the generator is lower. . The charging abnormality determining unit determines that the current sensor is abnormal if the detected value of the current sensor is a value on the discharge side when the charging determining unit determines that charging is being performed. The current sensor abnormality determination device according to any one of claims 1 to 3, wherein Discharge determination means for determining whether or not the battery is discharging;
When the discharge determination means determines that the current sensor is discharging, if the absolute value of the detection value of the current sensor is equal to or greater than a predetermined discharge threshold value, it is determined that the current sensor is abnormal. Means,
With
The current sensor according to any one of claims 1 to 4, wherein the discharge threshold value is set based on a sum of maximum current consumption values of the plurality of electric loads mounted on the vehicle. Abnormality judgment device. A generator mounted on the vehicle; a battery that charges the generated power by the generator and discharges to an electric load mounted on the vehicle; a current sensor that detects a battery current when the battery is charged and discharged; Applied to a vehicle power system comprising
Discharge determination means for determining whether or not the battery is discharging;
When the discharge determination means determines that the current sensor is discharging, if the absolute value of the detection value of the current sensor is equal to or greater than a predetermined discharge threshold value, it is determined that the current sensor is abnormal. Means,
With
The discharge threshold value is set based on the sum of the maximum current consumption values of the plurality of electric loads mounted on the vehicle ,
The plurality of electric loads mounted on the vehicle are supplied with a constant voltage required electric load that is applied by boosting the voltage of the discharge power of the battery by a booster circuit, and the discharge power without being boosted by the booster circuit. Includes general electrical loads,
In the case where the booster circuit has a current detection circuit that detects its own output current value,
The discharge threshold value is set based on a value obtained by adding a current value detected by the current detection circuit to a sum of maximum current consumption values of the general electric load. The plurality of electric loads mounted on the vehicle are supplied with a constant voltage required electric load that is applied by boosting the voltage of the discharge power of the battery by a booster circuit, and the discharge power without being boosted by the booster circuit. Includes general electrical loads,
In the case where the booster circuit has a current detection circuit that detects its own output current value,
6. The current sensor abnormality according to claim 5, wherein the discharge threshold value is set based on a value obtained by adding a current value detected by the current detection circuit to a sum of maximum current consumption values of the general electric load. Judgment device. The discharge abnormality determination means determines that the current sensor is abnormal if the detected value of the current sensor is a charge-side value when it is determined that the discharge determination means is discharging. The current sensor abnormality determination device according to claim 5, wherein the abnormality determination device is a current sensor abnormality determination device.   The discharge determination means determines whether or not the battery is discharging based on whether or not the generator is generating electricity. 9. The current sensor abnormality determination device described.

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