JP2020038122A - Power storage system and abnormality determination method - Google Patents

Abstract

To facilitate accurate detection of abnormality on a sensor side.SOLUTION: A power storage system includes: a driving secondary battery for an electric vehicle; a load connected to the driving secondary battery; a sensor part including a first sensor for measuring a value related to a current at a given spot between the driving secondary battery and the load, and a second sensor for measuring a value related to a current at the given spot; and a process part for obtaining a signal output from the sensor part. Further, the process part refers to a prepared current-voltage characteristic, and calculates a current value input and output to and from the driving secondary battery by using the signal output from the sensor part. In the system, a first resistor is connected to an output side of the first sensor, and a second resistor is connected to an output side of the second sensor, where the first resistor and the second resistor have different resistance values.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage system and an abnormality determination method.

  The electric vehicle includes a motor for driving the vehicle, a secondary battery for supplying power to the motor, a control unit for controlling power supply from the secondary battery to the motor, and the like. The control unit is configured to control a state of charge (SOC) of the secondary battery based on an output of a current sensor that detects input / output power of the secondary battery, an output of a voltage sensor that detects a voltage of the secondary battery, and the like. Is calculated. Then, the control unit controls charging and discharging from the secondary battery based on the calculation result. There is known a technique for determining the presence or absence of an abnormality in a secondary battery using the output of the current sensor (for example, see Patent Document 1).

JP 2018-77999 A

  However, in the related art, when an abnormality such as a short-circuit current flows in the sensor, it may not be possible to determine whether an abnormality has occurred in the sensor based on the output of the sensor.

  SUMMARY An advantage of some aspects of the invention is to provide a power storage system that can accurately detect an abnormality on a sensor side and an abnormality determination method.

  (1): A power storage system according to one embodiment of the present invention includes a driving secondary battery for an electric vehicle, a load connected to the driving secondary battery, and the driving secondary battery and the load. A sensor unit including a first sensor that measures a value of the current at a predetermined location between the first sensor and a second sensor that measures a value of the current at the predetermined location, and a processing unit that acquires a signal output by the sensor unit. The processing unit refers to a current-voltage characteristic prepared in advance, using a signal output by the sensor unit, calculates a current value input / output to the driving secondary battery, A first resistor is connected to the output side of the first sensor, a second resistor is connected to the output side of the second sensor, and the first resistor and the second resistor have a large resistance. Are different.

  (2): In the above aspect (1), the processing unit calculates a difference between the magnitude of the resistance of the first resistor and the magnitude of the resistance of the second resistor with respect to the current value at the predetermined location. It is determined based on the error of the current value.

  (3): In the above aspect (1) or (2), the first sensor, the second sensor, the first resistor, and the second resistor are housed in one housing. Is what it is.

  (4): The power storage system according to one embodiment of the present invention includes a driving secondary battery for an electric vehicle, a load connected to the secondary battery, and a load between the driving secondary battery and the load. A sensor unit including a first sensor that measures a value related to the current at a predetermined location and a second sensor that measures a value related to the current at the predetermined location; and a processing unit that acquires a signal output by the sensor unit. The processing unit refers to a current-voltage characteristic prepared in advance, calculates a current value input / output to / from the driving secondary battery using a signal output by the sensor unit, A resistor is connected to the output side of the sensor, and no resistor is connected to the output side of the second sensor.

  (5) In the aspect of (4), the magnitude of the resistance of the resistor is determined based on an error between the current value at the predetermined location and the current value calculated by the processing unit.

  (6): In the above aspect (4) or (5), the first sensor, the second sensor, and the resistor are housed in one housing.

  (7): In any one of the above aspects (1) to (6), the processing unit may calculate a first current value calculated based on a signal output from the first sensor, and The apparatus further includes an abnormality determination unit that determines whether there is an abnormality in the sensor unit based on a difference from the second current value calculated based on the output signal.

  (8): In the aspect of (7), when the absolute value of the difference between the first current value and the second current value is equal to or greater than a threshold, the abnormality determination unit determines that there is an abnormality in the sensor unit. It is to judge.

  (9): In any one of the above aspects (1) to (8), in the current-voltage characteristics, a first characteristic line indicating a current-voltage characteristic of the first sensor and a current-voltage characteristic of the second sensor may be used. The inclination with the second characteristic line shown is different from each other.

  (10) In any one of the above aspects (1) to (9), in the current-voltage characteristic, a first characteristic line indicating a current-voltage characteristic of the first sensor and a current-voltage characteristic of the second sensor are used. The second characteristic line shown has an intersection, and the absolute value of the inclination of the first characteristic line is the same as the absolute value of the inclination of the second characteristic line.

  (11): The abnormality determination method according to an aspect of the present invention includes a driving secondary battery for an electric vehicle, a load connected to the driving secondary battery, the driving secondary battery, and the load. And a sensor unit including a first sensor that measures a value of the current at a predetermined location between the first sensor and a second sensor that measures a value of the current at the predetermined location. A signal output from the sensor and the second sensor is obtained, and the second characteristic line is a previously prepared current-voltage characteristic, and the first characteristic line corresponding to the first sensor has a different slope from the first characteristic line. With reference to a second characteristic line corresponding to a sensor, a first current value input / output to / from the driving secondary battery using the acquired signal output by the first sensor, and the acquired Output by one sensor A second current value input / output to / from the driving secondary battery is calculated using the obtained signal, an absolute value of a difference between the calculated first current value and the second current value, and a predetermined threshold value are calculated. Is used to determine whether the first sensor or the second sensor is abnormal.

  (12): In the aspect of (11), in the current-voltage characteristic, the first characteristic line and the second characteristic line intersect, and the inclination of the first characteristic line and the inclination of the second characteristic line are different. If they are different from each other, it is determined whether or not the absolute value of the difference between the first current value and the second current value is equal to or larger than a threshold. Is determined to have occurred.

  (13): In the above aspect (11) or (12), the threshold value is determined based on at least one of detection accuracy of the sensor unit and calculation accuracy of a current value of the computer.

  According to (1) to (13), an abnormality on the sensor side can be accurately detected.

FIG. 1 is a diagram illustrating an example of a configuration of a vehicle equipped with a power storage system 1. FIG. 3 is a diagram illustrating an example of a configuration of a current sensor unit 90. FIG. 21 is a diagram showing an example of a current-voltage characteristic diagram 201. FIG. 4 is a diagram for describing a current flow in a short circuit between pins. FIG. 21 is a diagram showing an example of a current-voltage characteristic diagram 202. FIG. 4 is a configuration diagram of a comparative configuration example. FIG. 13 is a diagram illustrating an example of a current-voltage characteristic diagram 301 in a comparative configuration example. It is a figure which shows the comparison of the graph of a short circuit part voltage. 5 is a flowchart illustrating a flow of a process performed by a processing unit. FIG. 3 is a diagram illustrating an example of a configuration of a current sensor unit 95. FIG. 209 is a diagram illustrating an example of a current-voltage characteristic diagram 203. FIG. 3 is a diagram illustrating an example of a hardware configuration of a processing unit according to the embodiment.

  Hereinafter, an embodiment of a power storage system and an abnormality determination method of the present invention will be described with reference to the drawings.

<First embodiment>
[overall structure]
FIG. 1 is a diagram illustrating an example of a configuration of an electric vehicle equipped with a power storage system 1. The electric vehicle on which the power storage system 1 is mounted is, for example, a two-wheel, three-wheel, four-wheel, or other vehicle, and its driving source is an electric motor or a combination of the electric motor and an internal combustion engine such as a diesel engine or a gasoline engine. The electric motor operates using the discharge power of the secondary battery. In the following description, as an example, the electric vehicle will be described as a hybrid vehicle that uses an engine or an electric motor as a drive source.

  As shown in FIG. 1, the power storage system 1 includes, for example, an engine 10, a motor 20, a PCU (Power Control Unit) 30, a secondary battery (storage battery) 40, driving wheels 50, a current sensor unit 90, a processing unit 100, and the like. Is mounted.

  The engine 10 is an internal combustion engine that outputs power by burning fuel such as gasoline. The engine 10 is, for example, a reciprocating engine including a cylinder and a piston, an intake valve, an exhaust valve, a fuel injection device, a spark plug, a connecting rod, a crankshaft, and the like. Further, the engine 10 may be a rotary engine.

  The motor 20 is, for example, a three-phase AC generator. The motor 20 is, for example, an electric motor for traveling. The motor 20 outputs power to the driving wheels 50 using the supplied power. Further, the motor 20 generates electric power using kinetic energy of the electric vehicle when the electric vehicle decelerates. The motor 20 drives and regenerates the electric vehicle. The regeneration is a power generation operation by the motor 20. The motor 20 may include a motor for power generation. The power generation motor generates power using, for example, motive power output from the engine 10.

  The PCU 30 includes, for example, a converter 32 and a VCU (Voltage Control Unit) 34. It should be noted that the configuration of these components as a unit as the PCU 30 is merely an example, and these components may be distributed.

  The converter 32 is, for example, an AC-DC converter. The DC terminal of the converter 32 is connected to the VCU 34 via the DC link DL. The converter 32 converts AC generated by the motor 20 into DC and outputs the DC to the DC link DL, or converts DC supplied via the DC link DL into AC and supplies the AC to the motor 20.

  The VCU 34 is, for example, a DC-DC converter. VCU 34 boosts the power supplied from secondary battery 40 and outputs the boosted power to converter 32.

  The secondary battery 40 is, for example, a secondary battery such as a lithium ion battery. The secondary battery 40 is connected to the PCU 30 via a power line 80.

  Current sensor unit 90 is arranged on power line 80. The current sensor unit 90 includes a plurality of current sensors that measure information (for example, magnetic flux) on the magnitude of current at a predetermined measurement point on the power line 80. For example, the current sensor unit 90 includes a first current sensor 91 and a second current sensor 92.

  FIG. 2 is a diagram illustrating an example of the configuration of the current sensor unit 90. The current sensor unit 90 includes a first current sensor 91 and a second current sensor 92. That is, the first current sensor 91 and the second current sensor 92 are housed in one housing.

  Further, for example, the first current sensor 91 and the second current sensor 92 are arranged adjacently or separated from each other by about several mm to several cm. The first current sensor 91 and the second current sensor 92 may be provided on, for example, one substrate. The first current sensor 91 and the second current sensor 92 are designed to output a predetermined signal according to the magnitude of the current. Although details will be described later, the first current sensor 91 and the second current sensor 92 are designed to output signals indicating different output voltage values according to the magnitude of the current. Note that the relationship between the magnitude of the current that actually flows and the magnitude of the output voltage output by each sensor is determined in a voltage-current characteristic described later.

  The current sensor unit 90 includes a power terminal VCC connected to a power terminal of the battery ECU, an output terminal OUT1 of the first current sensor 91, an output terminal OUT2 of the second current sensor, and GND. Each is connected to the processing unit 100.

  The first current sensor 91 includes a core (not shown) having an air gap, a magnetic detection IC 91A, a first resistor 91B, and the like. The core is arranged such that the power line 80 passes through the space inside the core. The magnetic detection IC 91A outputs a signal including the magnitude of a voltage corresponding to the magnetic flux generated in the air gap. The magnetic detection IC 91A includes, for example, a magnetic detection element and an operational amplifier for voltage amplification, and has various correction functions. The first resistor 91B is connected to the output side of the magnetic detection IC 91A. The signal output by the magnetic detection IC 91A is output to the processing unit 100 via the first resistor 91B and the output terminal OUT1.

  The second current sensor 92 includes a core having an air gap, a magnetic detection IC 92A, a second resistor 92B, and the like. The core is arranged such that the power line 80 passes through the space inside the core. The magnetic detection IC 92A outputs a signal including the magnitude of the voltage corresponding to the magnetic flux generated in the air gap. The second resistor 92B is connected to the output side of the magnetic detection IC 92A. The signal output by the magnetic detection IC 92A is output to the processing unit 100 via the second resistor 92B and the output terminal OUT2.

  The first resistor 91B and the second resistor 92B have different resistances. For example, the resistance value R1 of the first resistor 91B is 1 kΩ and the resistance value R2 of the second resistor 92B is 10 kΩ.

  The difference between the magnitude of the resistance of the first resistor 91B and the magnitude of the resistance of the second resistor 92B is determined by the control battery current Ib ( (To be described later). For example, the error of the first input / output current I1 calculated based on the signal output from the first resistor 91B is ± 5%, and is calculated based on the signal output from the second resistor 92B. When the error of the second input / output current I2 is ± 5%, the maximum mutual error is ± 10%. In this case, the divided voltage of the output voltage when the first current sensor 91 and the second current sensor 92 are short-circuited is set to ± 10% of the mutual difference between the first input / output current I1 and the second input / output current I2 when the short-circuit occurs. Set so as to be as described above. For example, in the case of a current-voltage characteristic to be described later (the absolute value of the gradient is the same and the polarity is opposite), the resistance of the first resistor 91B is set to 45 kΩ or less and the resistance of the second resistor 92B is set to 55 kΩ or more. As described above, the voltage division of the output voltage of the sensor can be set. The error depends on, for example, the environment (mainly temperature) of the power storage system 1. Power storage systems mounted on electric vehicles are susceptible to, for example, temperature changes. Therefore, by determining the resistance value of the resistor based on the mutual error, the accuracy of determining whether the current sensor unit 90 is abnormal can be improved.

  Returning to FIG. 1, the processing unit 100 includes a current calculation unit 111, an abnormality determination unit 113, and a storage unit 130. The current calculation unit 111 and the abnormality determination unit 113 are realized by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). In addition, some or all of these components include hardware (circuits) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), and a GPU (Graphics Processing Unit). (Including a circuitry), or may be realized by cooperation of software and hardware. The storage unit 130 includes, for example, a nonvolatile storage device such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable and Programmable Read Only Memory), a HDD (Hard Disk Drive), and a RAM (Random Access Memory) and a register. This is realized by a volatile storage device.

  The current calculator 111 obtains the output voltage V1 of the first current sensor 91 based on the voltage signal output from the output terminal OUT1. The current calculator 111 acquires the output voltage V2 of the second current sensor 92 based on the voltage signal output from the output terminal OUT2.

  The current calculation unit 111 refers to a current-voltage characteristic prepared in advance (details will be described later), and based on the obtained output voltage, a current value input / output to / from the secondary battery 40 (hereinafter, a control battery current). Ib) is calculated. The control battery current Ib is used to control charging and discharging by the secondary battery 40. Information indicating the current-voltage characteristic is stored in the storage unit 130 as current-voltage characteristic information 132. The current-voltage characteristic information 132 may be a calculation formula, a table, a graph, a diagram, a map, or the like. The “process of calculating the control battery current Ib based on the output voltage with reference to the current-voltage characteristics” includes a process of calculating the control battery current value Ib by substituting the output voltage into a calculation formula, a table, The processing includes obtaining a control battery current value Ib obtained by applying an output voltage to information indicating a correspondence relationship such as a graph, a diagram, and a map.

  For example, the current calculation unit 111 calculates the first input / output current I1 corresponding to the output voltage V1 from the first current sensor 91 with reference to the current-voltage characteristics. Further, the current calculation unit 111 calculates the second input / output current I2 corresponding to the output voltage V2 from the second current sensor 92 with reference to the current-voltage characteristics. Current calculation section 111 outputs the calculation result to abnormality determination section 113.

  When the abnormality determination unit 113 determines that there is no abnormality on the current sensor unit 90 side, the current calculation unit 111 sets the calculated first input / output current I1 or second input / output current I2 as the control battery current Ib. . For example, the current calculated based on the output from the main sensor is set as the control battery current Ib. In the embodiment, it is determined that the first current sensor 91 is a main sensor and the second current sensor 92 is a sub sensor.

  When the abnormality determination unit 113 determines that there is an abnormality, the current calculation unit 111 may not set any of the input / output currents I1 and I2 to the control battery current Ib. In this case, it is treated as a state where the control battery current Ib cannot be measured. Further, even when it is determined that the current sensor unit 90 has an abnormality, if the abnormality is not an abnormality in the sensor set as the main sensor, the current calculation unit 111 outputs the output voltage from the main sensor. May be determined as the control battery current Ib.

  FIG. 3 is a diagram illustrating an example of the current-voltage characteristic diagram 201. In the current-voltage characteristic diagram 201, the horizontal axis represents input / output current, and the vertical axis represents output voltage. The left axis of the vertical axis is the output voltage V1 from the first current sensor 91, and the right axis of the vertical axis is the output voltage V2 from the second current sensor 92. In the input / output current on the horizontal axis, a positive value is a current value of power output (discharged) from the secondary battery 40, and a negative value is a current value of power input (charged) to the secondary battery 40. Value.

  In the current-voltage characteristic diagram 201, the characteristic graph Y1 of the first current sensor 91 and the characteristic graph Y2 of the second current sensor 92 have an intersection X1. The intersection X1 is set at a position where the control battery current Ib = 0A. Further, the absolute value of the slope of the characteristic graph Y1 is the same as the absolute value of the slope of the characteristic graph Y2. For example, in FIG. 3, the characteristic graph Y1 rises in the upper right direction and the characteristic graph Y2 rises in the upper left direction with the same tendency.

  Note that the slope of the characteristic graph Y1 and the slope of the characteristic graph Y2 may be different from each other, and the absolute values of the slopes may not be the same.

  For example, when the output voltage V1 from the first current sensor 91 is Vx = Vx1, the current calculation unit 111 calculates the first input / output current I1 = -Ix1 with reference to the current-voltage characteristic diagram 201. When the output voltage V2 from the second current sensor 92 is V2 = Vx2V, the current calculation unit 111 calculates the second input / output current I2 = −Ix1A with reference to the current-voltage characteristic diagram 201. As described above, when the first input / output current I1 = the second input / output current I2 (because the abnormality determination unit 113 determines that there is no abnormality), the current calculation unit 111 The current value of the control battery current Ib is determined to be -Ix1.

  The abnormality determination unit 113 determines whether there is an abnormality in the current sensor unit 90 based on the difference between the first input / output current I1 and the second input / output current I2 calculated by the current calculation unit 111. For example, when the absolute value of the difference between the first input / output current I1 and the second input / output current I2 is less than the threshold th1, the abnormality determination unit 113 determines that the current sensor unit 90 has no abnormality. On the other hand, when the absolute value of the difference between the first input / output current I1 and the second input / output current I2 is equal to or larger than the threshold th1, the abnormality determination unit 113 determines that the current sensor unit 90 has an abnormality. For example, when the threshold value th1 = 20, the first input / output current I1 = −200 A, and the second input / output current I2 = + 200 A, the absolute value of the difference (| I1−I2 |) = 400. For this reason, the abnormality determination unit 113 determines that there is an abnormality on the current sensor side. When the threshold value th1 = 10, the first input / output current I1 = + 5 A, and the second input / output current I2 = + 3 A, the absolute value of the difference (| I1-I2 |) = 2. Therefore, the abnormality determination unit 113 determines that there is no abnormality on the current sensor side.

  The threshold value th1 is not limited to this, and can be set arbitrarily. For example, the threshold th1 is determined based on at least one of the detection accuracy of the current sensor unit 90 (the first current sensor 91 and the second current sensor 92) and the calculation accuracy of the current value of the current calculation unit 111. For example, when the detection error of the first current sensor 91 is about 5% of the actual value and the detection error of the second current sensor 92 is about 5% of the actual value, at least about 10% The threshold is set so that the margin is included in the threshold. When the calculation error of the current calculation unit 111 is about 5% of the actual value, the threshold is set so that at least a margin of about 15% is included in the threshold.

  Hereinafter, a process performed when an inter-pin short has occurred will be described. FIG. 4 is a diagram for describing a current flow in a short circuit between pins. The pin-to-pin short is caused by, for example, a point P1 between the first resistor 91B and the output terminal OUT1 and a point between the second resistor 92B and the output terminal OUT2 due to harness jamming or a malfunction of the output terminal. P2 is short-circuited, and a short-circuit current flows between point P1 and point P2.

  When a short circuit occurs between the pins, the output voltage V1 from the first current sensor 91 and the output voltage V2 from the second current sensor 92 have the same value.

For example, a voltage (hereinafter, a short-circuit portion voltage Vs) when a short circuit occurs between pins is obtained by the following equation (1) or equation (2).
Vs = (R2 * V'1 + R1 * V'2) / R1 + R2 (1)
Vs = V'2 + (R2 * Is) (2)
Is = ΔV / (R1 + R2) (3)
V′1 is a voltage value that should have been output from the first current sensor 91 when no short circuit occurred between the pins.
V′2 is a voltage value that should have been output from the second current sensor 92 when a short circuit between the pins did not occur.
ΔV is the difference in magnitude between V′1 and V′2.

  According to the above equation, the short circuit voltage Vs is not constant because R1 and R2 are different. For example, when V′1 = 2.8V, V′2 = 2.2V, R1 = 1 kΩ, and R2 = 10 kΩ, the short-circuit voltage Vs is 2.75V. When V′1 = 0.8 V, V′2 = 4.2 V, R1 = 1 kΩ, and R2 = 10 kΩ, the short circuit voltage Vs is 3.89 V. In other words, by configuring the resistance values of the first resistor 91B and the second resistor 92B to be different from each other, the output voltage at the time of short between pins becomes V′1 and V′2, It becomes dependent on R1 and R2.

  FIG. 5 is a diagram illustrating an example of the current-voltage characteristic diagram 202. The current-voltage characteristic diagram 202 includes a graph Y3 of the short-circuit portion voltage Vs that satisfies Expression (1) described above. Note that the description that overlaps with the current-voltage characteristic diagram 201 shown in FIG. 3 is omitted. For example, if the short-circuit voltage Vs = Vx11, the current calculator 111 calculates the first input / output current I1 = −Ix11 and the second input / output current I2 = + Ix11. The abnormality determination unit 113 determines whether the absolute value of the difference between the first input / output current I1 and the second input / output current I2 is equal to or smaller than a threshold th1. When the absolute value of the difference (| −Ix11−Ix11 |) = 2 × (Ix11) is equal to or larger than the threshold th1, the abnormality determination unit 113 determines that there is an abnormality.

  The present invention is not limited to this, and the abnormality determination unit 113 may determine that there is an abnormality when the control battery current Ib calculated by the current calculation unit 111 does not match. Also in this case, for example, the presence or absence of an abnormality can be determined by the above-described method (a method of comparing the absolute value of the difference with the threshold th1).

[Comparison with comparative configuration example]
Next, a comparative configuration example will be described with reference to FIGS. FIG. 6 is a configuration diagram of a comparative configuration example. As shown in FIG. 6, the comparative configuration example includes a current sensor 71 and a current sensor 72. The current sensor 71 includes a core (not shown) having an air gap, a magnetic detection IC 71A, a resistor 71B, and the like. The current sensor 72 includes a core (not shown) having an air gap, a magnetic detection IC 72A, a resistor 72B, and the like. The comparative configuration example is not limited to this, and for example, may be a configuration that does not include a resistor on the output side of both sensors.

  In the comparative configuration example shown in FIG. 6, when a short between pins occurs, the output voltage V71 from the current sensor 71 and the output voltage V72 from the current sensor 72 have the same value (in the case where no short between pins occurs). (An intermediate value of the voltage that should have been output from each current sensor).

For example, the short-circuit voltage Vsp is obtained by the following equation (4) or equation (5).
Vsp = (R72 * V'71 + R71 * V'72) / R71 + R72 (4)
Vsp = V'72 + (R72 * Isp) (5)
Isp = ΔVp / (R71 + R72) (6)
V′71 is a voltage value that should have been output from the current sensor 71 when no short circuit occurred between the pins.
V′72 is a voltage value that should have been output from the current sensor 72 when a short circuit between pins did not occur.
ΔVp is the difference between the magnitudes of V′71 and V′72.

  According to the above equation, since R71 and R72 are the same, the short circuit voltage Vsp is constant. For example, the short circuit voltage Vsp = (V'71 + V'72) / 2. More specifically, the short circuit voltage Vsp in the case of V'71 = 2.8 V, V'72 = 2.2 V, R71 = 1 kΩ, and R72 = 1 kΩ is 2.5 V. That is, even if V'71 and V'72 are different values, the short circuit voltage Vsp is always 2.5V.

  FIG. 7 is a diagram illustrating an example of a current-voltage characteristic diagram 301 in the comparative configuration example. The current-voltage characteristic diagram 301 is a graph in which the short-circuit portion voltage Vsp in the comparative configuration example is plotted. The characteristic graph Y31 of the current sensor 71 and the characteristic graph Y32 of the current sensor 72 have an intersection X33 similarly to the above-described characteristic graphs Y1 and Y2, and have the same absolute value of the slope. In the comparative configuration example, when a short between pins occurs, the output voltage becomes an intermediate value (for example, 2.5 V) of the output voltage that would have been output from each current sensor when the short between pins did not occur. . Therefore, the graph of the short-circuit portion voltage Vsp becomes like Y34. That is, the control battery current Ib when the short circuit occurs between the pins is always Ix21. Therefore, it is indistinguishable between the case where the control battery current Ib becomes Ix21 (when the actual current value is Ix21) and the case where the inter-pin short occurs when no short-circuit between the pins has occurred. Was.

  As described above, in the present embodiment, as shown in FIG. 8, the output voltage characteristic at the time of short-circuiting is a characteristic line in which Y34 rotates clockwise to approach Y1 with the intersection point with Y1 as a fulcrum. That is, the characteristics of the short-circuit portion voltage are closer to the current-voltage characteristics of the smaller resistance value of the resistor. When Y3 is compared with Y34, the short-circuit portion voltage changes in accordance with the voltage value that should have been output from the current sensor 71 when the inter-pin short did not occur. , Y34 are always constant values.

  As described above, the power storage system 1 can accurately detect an abnormality in the current sensor based on the current value of the first current sensor and the current value of the second current sensor at the time of short-circuit.

[flowchart]
FIG. 9 is a flowchart showing the flow of processing by the processing unit 100. First, the current calculator 111 acquires an output voltage V1 based on a signal output from the first current sensor 91 (Step S101). The current calculation unit 111 calculates the first input / output current I1 corresponding to the output voltage V1 from the first current sensor 91 with reference to the current-voltage characteristic diagram stored in the storage unit 130 (Step S103). Next, the current calculator 111 acquires the output voltage V2 based on the signal output from the second current sensor 92 (Step S105). The current calculation unit 111 calculates the second input / output current I2 corresponding to the output voltage V2 from the second current sensor 92 with reference to the current-voltage characteristic diagram stored in the storage unit 130 (Step S107).

  The abnormality determination unit 113 calculates the absolute value of the difference between the first input / output current I1 and the second input / output current I2 calculated by the current calculation unit 111, and determines whether the calculated absolute value of the difference is smaller than the threshold th1. It is determined whether or not it is (step S109). If the calculated absolute value of the difference is less than the threshold th1, the abnormality determination unit 113 determines that there is no abnormality in the current sensor unit 90 (step S111). On the other hand, when the calculated absolute value of the difference is equal to or larger than the threshold th1, the abnormality determination unit 113 determines that the current sensor unit 90 has an abnormality (step S113).

  Note that the threshold th1 may be determined based on a voltage value at the time of short between pins. For example, the threshold value th1 may be increased as the voltage value increases (increases or decreases) from the intersection X in the current-voltage characteristic diagram.

  The threshold value th1 is such that when a voltage value that should have been output from the current sensor unit 90 when a short circuit between pins did not occur is equal to or higher than a predetermined value, it can be determined that a short circuit between pins has occurred. Value may be set. By doing so, the influence of the erroneous detection of the input / output power of the secondary battery 40 is higher when the output voltage is high than when the output voltage is low.

  According to the first embodiment described above, the drive secondary battery 40 for the electric vehicle, the load connected to the secondary battery 40, and the current at a predetermined location between the secondary battery 40 and the load A current sensor unit 90 including a first current sensor 91 for measuring a value, a second current sensor 92 for measuring a value related to a current at a predetermined location, and a processing unit 100 for acquiring a signal output by the current sensor unit 90. The processing unit 100 calculates a current value input to and output from the secondary battery 40 using the signal output from the current sensor unit 90 with reference to a current-voltage characteristic prepared in advance. The first resistor 91B is connected to the output side of the one current sensor 91, the second resistor 92B is connected to the output side of the second current sensor 92, and the first resistor 91B and the second resistor 92B , Because of the different resistance The capacitors side of abnormality can be accurately detected.

<Second embodiment>
FIG. 10 is a diagram illustrating an example of the configuration of the current sensor unit 95. Note that the description of the same content as the description using FIG. 2 is omitted. The current sensor unit 95 includes a first current sensor 96 and a second current sensor 97. That is, the first current sensor 96 and the second current sensor 97 are housed in one housing. The first current sensor 96 includes a core (not shown) having an air gap, and a magnetic detection IC 96A. The second current sensor 97 includes a core (not shown) having an air gap, a magnetic detection IC 97A, and a resistor 97B. That is, a resistor is connected to the output side of the second current sensor 97, and no resistor is connected to the output side of the first current sensor 96. Note that, instead of the resistor 97B, the first current sensor 96 may have a configuration including a resistor. That is, only one of the first current sensor 96 and the second current sensor 97 includes a resistor. For example, the resistance value of the resistor 97B is 10 kΩ.

  According to the second embodiment described above, the same effects as those of the first embodiment can be obtained.

<Third embodiment>
For example, in the current-voltage characteristic diagram, the first characteristic graph showing the current-voltage characteristic of the first current sensor 91 and the second characteristic graph showing the current-voltage characteristic of the second current sensor 92 have no intersection. There may be.

  FIG. 11 is a diagram illustrating an example of the current-voltage characteristic diagram 203. Here, points different from the current-voltage characteristic diagram 201 shown in FIG. 3 will be described. In the current-voltage characteristic diagram 203, the characteristic graph Y11 of the first current sensor 91 and the characteristic graph Y12 of the second current sensor 92 have no intersection. The inclination of the characteristic graph Y11 is the same as the inclination of the characteristic graph Y12. The inclination of the characteristic graph Y11 may be different from the inclination of the characteristic graph Y12.

  Y13 is a graph showing the characteristics of the output voltage (short-circuit portion voltage Vs) when the pins are short-circuited. For example, when the short-circuit voltage Vs = Vx31, the current calculation unit 111 calculates the first input / output current I1 = Ix31 and the second input / output current I2 = Ix32. The abnormality determination unit 113 determines whether the absolute value of the difference between the first input / output current I1 and the second input / output current I2 is within a predetermined range including the threshold th2. If the absolute value of the difference is not within the predetermined range including the threshold th2, the abnormality determination unit 113 determines that the current sensor unit 90 has an abnormality. On the other hand, when the absolute value of the difference is within the predetermined range including the threshold th2, the abnormality determination unit 113 determines that the current sensor unit 90 has no abnormality.

[Hardware configuration]
The processing unit 100 of the power storage system 1 according to the above-described embodiment is realized by, for example, a hardware configuration as illustrated in FIG. FIG. 12 is a diagram illustrating an example of a hardware configuration of a processing unit according to the embodiment.

  The processing unit 100 includes a communication controller 100-1, a CPU 100-2, a RAM 100-3, a ROM 100-4, a secondary storage device 100-5 such as a flash memory or an HDD, and a drive device 100-6 which are connected to an internal bus or dedicated communication. They are connected to each other by wires. A portable storage medium such as an optical disk is mounted on the drive device 100-6. The program 100-5a stored in the secondary storage device 100-5 is developed in the RAM 100-3 by a DMA controller (not shown) or the like, and is executed by the CPU 100-2, thereby realizing a functional unit of the processing unit 100. You. The program referred to by the CPU 100-2 may be stored in a portable storage medium mounted on the drive device 100-6, or may be downloaded from another device via the network NW.

The above embodiment can be expressed as follows.
A storage device;
A hardware processor that executes a program stored in the storage device,
A signal output by a sensor unit including a first sensor that measures a value related to a current at a predetermined location between the driving secondary battery and the load and a second sensor that measures a value related to a current at the predetermined location is acquired. ,
With reference to a current-voltage characteristic prepared in advance, using a signal output by the sensor unit, a current value input / output to / from the driving secondary battery is calculated,
A first resistor is connected to an output side of the first sensor,
A second resistor is connected to an output side of the second sensor,
The power storage system is configured such that the first resistor and the second resistor have different resistances.

  As described above, the embodiments for carrying out the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments at all, and various modifications and substitutions may be made without departing from the gist of the present invention. Can be added.

10 Engine 20 Motor 30 PCU
32 converter 34 VCU
40 secondary battery 90 current sensor unit 91 first current sensor 92 second current sensor 100 processing unit 111 current calculation unit 113 abnormality determination unit 130 storage unit

Claims (13)

A driving secondary battery for an electric vehicle;
A load connected to the driving secondary battery,
A sensor unit including a first sensor that measures a value related to a current at a predetermined location between the driving secondary battery and the load, and a second sensor that measures a value related to a current at the predetermined location;
A processing unit that acquires a signal output by the sensor unit,
The processing unit refers to a current-voltage characteristic prepared in advance, and calculates a current value input / output to / from the driving secondary battery by using a signal output by the sensor unit.
A first resistor is connected to an output side of the first sensor,
A second resistor is connected to an output side of the second sensor,
The first resistor and the second resistor have different resistances;
Energy storage system. The difference between the magnitude of the resistance of the first resistor and the magnitude of the resistance of the second resistor is determined based on an error in the current value calculated by the processing unit with respect to the current value at the predetermined location.
The power storage system according to claim 1. The first sensor, the second sensor, the first resistor, and the second resistor are housed in one housing.
The power storage system according to claim 1. A driving secondary battery for an electric vehicle;
A load connected to the driving secondary battery,
A sensor unit including a first sensor that measures a value related to a current at a predetermined location between the driving secondary battery and the load, and a second sensor that measures a value related to a current at the predetermined location;
A processing unit that acquires a signal output by the sensor unit,
The processing unit refers to a current-voltage characteristic prepared in advance, and calculates a current value input / output to / from the driving secondary battery by using a signal output by the sensor unit.
A resistor is connected to an output side of the first sensor,
A power storage system in which a resistor is not connected to an output side of the second sensor. The magnitude of the resistance of the resistor is determined based on an error in the current value calculated by the processing unit with respect to the current value at the predetermined location.
The power storage system according to claim 4. The first sensor, the second sensor, and the resistor are housed in one housing.
The power storage system according to claim 4. Based on a difference between a first current value calculated based on a signal output from the first sensor and a second current value calculated based on a signal output from the second sensor, Further comprising an abnormality determination unit that determines whether there is an abnormality in the sensor unit,
The power storage system according to any one of claims 1 to 6. When the absolute value of the difference between the first current value and the second current value is equal to or greater than a threshold, the abnormality determination unit determines that the sensor unit has an abnormality.
The power storage system according to claim 7. In the current-voltage characteristics, a slope of a first characteristic line indicating a current-voltage characteristic of the first sensor is different from a slope of a second characteristic line indicating a current-voltage characteristic of the second sensor.
The power storage system according to claim 1. In the current-voltage characteristics, a first characteristic line indicating a current-voltage characteristic of the first sensor and a second characteristic line indicating a current-voltage characteristic of the second sensor have an intersection, and the slope of the first characteristic line is The absolute value and the absolute value of the slope of the second characteristic line are the same,
The power storage system according to claim 1. A driving secondary battery for an electric vehicle;
A load connected to the driving secondary battery,
An electric vehicle comprising: a first sensor that measures a value related to a current at a predetermined location between the driving secondary battery and the load; and a sensor unit that includes a second sensor that measures a value related to a current at the predetermined location. The computer mounted on the
Acquiring signals output by the first sensor and the second sensor;
A first characteristic line corresponding to the first sensor and a second characteristic line corresponding to the second sensor having a different slope from the first characteristic line, wherein the first characteristic line corresponds to the first sensor;
A first current value input / output to / from the driving secondary battery using the obtained signal output by the first sensor; and a driving current using the obtained signal output by the first sensor. Calculating a second current value input / output to / from the secondary battery,
Determining an abnormality of the first sensor or the second sensor based on an absolute value of a difference between the calculated first current value and the second current value and a predetermined threshold value;
Abnormality determination method. In the current-voltage characteristics, when the first characteristic line and the second characteristic line intersect and the inclination of the first characteristic line and the inclination of the second characteristic line are different from each other, the first current value and the second characteristic line It is determined whether or not the absolute value of the difference with the second current value is equal to or greater than a threshold, and if the difference is equal to or greater than the threshold, it is determined that an abnormality has occurred in the sensor unit.
An abnormality determination method according to claim 11. The threshold is determined based on at least one of the detection accuracy of the sensor unit and the calculation accuracy of the current value of the computer,
An abnormality determination method according to claim 11.

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