JP2020193875A - Control device - Google Patents

Abstract

To provide a control device that can increase the accuracy of determining overcharge/discharge of a battery even when a voltage detection part is abnormal.SOLUTION: A control device includes a current detection unit that detects overcharging/discharging current of a battery, a voltage detection unit that detects the battery voltage of the battery, and a conversion unit that converts the charging/discharging current into a first digital signal and converts the battery voltage into a second digital signal. The SOC of the battery is calculated on the basis of the first digital signal. The overcharged/discharged state of the battery is determined on the basis of the second digital signal. The control device moreover includes an abnormality determination unit that determines an abnormality of the voltage detection unit, and a state determination unit that, upon the determination of the abnormality by the abnormality determination unit, changes the current range where the conversion unit converts the charging/discharging current into the first digital signal from a first range to a second range, which is smaller than the first range, and determines the overcharged/discharged state of the battery on the basis of the first digital signal converted in the second range.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device applied to a battery monitoring device.

As a control device of this type, for example, as seen in Patent Document 1 below, a device having a voltage detection unit and determining a battery abnormality based on the battery voltage detected by the voltage detection unit is known. In this device, the over-discharged state of the battery is determined based on the battery voltage. Further, when the abnormality of the voltage detection unit is determined and the voltage detection unit is determined to be abnormal, the charge / discharge current of the battery is suppressed as compared with the normal time. As a result, the battery can be continuously used while suppressing the charge / discharge current of the battery, and the influence on the system using the battery is reduced.

Japanese Unexamined Patent Publication No. 2000-357541

However, when the voltage detection unit is abnormal, the over-discharged state of the battery cannot be determined based on the battery voltage. In order to determine the over-discharged state of the battery even when the voltage detection unit is abnormal, for example, a current detection unit is provided, and the SOC is calculated using the integrated value of the charge / discharge current of the battery detected by the current detection unit. It is also conceivable to determine the over-discharged state of the battery based on this SOC.

In this case, since the SOC is calculated based on the integrated value of the charge / discharge current, the current range in which the current detection unit detects the charge / discharge current needs to be set widely so as to correspond to a wide range of charge / discharge current. The wider the current range of the current detection unit, the worse the detection accuracy of the charge / discharge current. Therefore, even if the over-discharge state of the battery is determined based on the integrated value of the charge / discharge current, the over-discharge state cannot be accurately determined.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a control device capable of improving the accuracy of battery overcharge / discharge determination even when the voltage detection unit is abnormal. It is in.

The first means for solving the above-mentioned problems is a current detection unit that detects the charge / discharge current of the battery, a voltage detection unit that detects the battery voltage of the battery, and the charge / discharge current of the charge / discharge current. The first digital is applied to a battery monitoring device including a conversion unit that converts the battery voltage into a second digital signal indicating a current value and a second digital signal indicating the voltage value of the battery voltage. It is a control device that calculates the SOC indicating the charge state of the battery based on the signal and determines the overcharge / discharge state of the battery based on the second digital signal, and determines the abnormality of the voltage detection unit. The current range in which the conversion unit converts the charge / discharge current into the first digital signal when the abnormality determination unit and the abnormality determination unit determine that the abnormality is present is set from the first range to the first range. Also includes a state determination unit that switches to a narrow second range and determines the overcharged / discharged state of the battery based on the first digital signal converted in the second range.

In the battery monitoring device, the conversion unit converts the charge / discharge current detected by the current detection unit into the first digital signal, and also converts the battery voltage detected by the voltage detection unit into the second digital signal. The control device of the battery monitoring device calculates the SOC of the battery based on the first digital signal, and determines the overcharged / discharged state of the battery based on the second digital signal. When the voltage detection unit is determined to be abnormal, the overcharge / discharge state of the battery is determined based on the first digital signal. That is, when the voltage detection unit is abnormal, the battery overcharge / discharge determination is performed based on the current detected by the current detection unit, instead of the battery overcharge / discharge determination based on the detection voltage of the voltage detection unit. However, the current detection by the current detector has low accuracy in order to correspond to a wide range of charge / discharge currents, but it widens the current range for detecting the charge / discharge currents, and is simply a parameter for determining battery overcharge / discharge. The accuracy of overcharge / discharge determination cannot be guaranteed simply by switching from voltage to current.

In this regard, in the above configuration, when the voltage detection unit is abnormal, the conversion unit switches the current range for converting the charge / discharge current into the first digital signal from the first range to the second range narrower than the first range. Since the configuration is such that the overcharge / discharge state of the battery is determined based on the first digital signal converted in the second range, the accuracy of the overcharge / discharge determination can be improved.

The second means includes a charge / discharge limiting unit that limits the charging / discharging of the battery so that the charging / discharging current becomes smaller than a predetermined value when the abnormality determining unit determines that the abnormality is present. The state determination unit switches the current range to the second range after the start of the limitation by the charge / discharge limiting unit.

If the charge / discharge current fluctuates beyond the second range after the current range of the conversion unit is switched to the second range, the charge / discharge current cannot be detected accurately, and the accuracy of the overcharge / discharge determination deteriorates. In this respect, in the above configuration, when the voltage detection unit is abnormal, the charge / discharge of the battery is limited so that the charge / discharge current becomes smaller than a predetermined value. Therefore, it is possible to suppress the charge / discharge current from fluctuating beyond the second range after the current range of the conversion unit is switched to the second range, and it is possible to improve the accuracy of the overcharge / discharge determination.

The third means includes a current determination unit that determines whether the charge / discharge current is smaller than the predetermined value after the start of restriction by the charge / discharge limiting unit, and the state determination unit is provided by the current determination unit. When it is determined that the value becomes smaller than the predetermined value, the current range is switched to the second range.

According to the above configuration, when it is determined that the charge / discharge current becomes smaller than the predetermined value, the current range is switched to the second range. Therefore, it is possible to reliably suppress the charge / discharge current from fluctuating beyond the second range after the current range of the conversion unit is switched to the second range, and it is possible to suitably improve the accuracy of the overcharge / discharge determination.

In the fourth means, the predetermined value is set so that the larger the SOC is, the smaller the value is when the battery is being charged, and the smaller the SOC is, the smaller the value is when the battery is discharged. A predetermined value setting unit for setting a predetermined value is provided.

When charging the battery, when the SOC is large, it is preferable to increase the degree of limitation of the charging current as compared with the case where the SOC is small, and it is preferable to set a predetermined value which is the upper limit of the charging current to be small. On the other hand, if the predetermined value is set to a small value until the SOC is small, the charging current is excessively limited, and charging of the battery is hindered. In this respect, in the above configuration, since the predetermined value is set so that the larger the SOC is, the smaller the value is, it is possible to preferably suppress the battery from being overcharged while suppressing an excessive limitation of the charging current.

Further, when the SOC is small when the battery is discharged, it is preferable to increase the degree of limitation of the charging current as compared with the case where the SOC is large, and it is possible to set a predetermined value which is the upper limit of the charging current to be small. preferable. On the other hand, if the predetermined value is set to a small value until the SOC is large, the discharge current is excessively limited and the battery discharge is hindered. In this respect, in the above configuration, since the predetermined value is set so that the smaller the SOC is, the smaller the value is, it is possible to preferably suppress the battery from being over-discharged while suppressing an excessive limitation of the discharge current.

In the fifth means, the state determination unit can change the width of the second range, and the width of the second range becomes narrower as the charge / discharge current becomes smaller.

According to the above configuration, the accuracy of the overcharge / discharge determination can be improved by narrowing the width of the second range as the charge / discharge current converges.

In the sixth means, the state determination unit determines the overcharge / discharge state of the battery using the integrated value of the charge / discharge current, and when the abnormality determination unit determines that the battery is abnormal, the abnormality determination is made. An initial value setting unit for setting an initial value of the integrated value is provided based on the previously detected average value of the battery voltage.

According to the above configuration, the estimation accuracy of the integrated value at the start of current integration can be improved, and the accuracy of the overcharge / discharge determination can be improved.

The overall block diagram of the battery monitoring apparatus which concerns on 1st Embodiment. The flowchart of the determination process which concerns on 1st Embodiment. The figure which shows the determination process of the overcharge state at the time of abnormality of a voltage sensor. The figure which shows the relationship between the charge / discharge current and the 1st digital signal which concerns on 1st Embodiment. The figure which shows the relationship between the resolution of a current sensor and the detection error. The figure which shows the conversion process of charge / discharge current by a conversion part. The flowchart of the determination process which concerns on 2nd Embodiment. The figure which shows the relationship between SOC and a predetermined current value. The figure which shows the transition of the predetermined current value during charging of a battery. The overall block diagram of the battery monitoring apparatus which concerns on 3rd Embodiment. The figure which shows the relationship between the charge / discharge current and the 1st digital signal which concerns on 3rd Embodiment. The flowchart of the determination process which concerns on 3rd Embodiment. The figure which shows the relationship between the charge / discharge current and the 2nd range. The figure which shows the switching process of the 2nd range in a control process.

(First Embodiment)
Hereinafter, the first embodiment in which the control device according to the present invention is applied to the vehicle-mounted battery monitoring device 100 will be described with reference to the drawings.

As shown in FIG. 1, the battery monitoring device 100 according to the present embodiment is a device that monitors the SOC (State Of Charge) indicating the charge state of the battery 40 and the charge / discharge state. The battery 40 is a rechargeable and dischargeable storage battery, specifically, an assembled battery in which a plurality of lithium ion storage batteries 41 are connected in series. The battery 40 may be another type of storage battery.

The battery 40 is connected to the rotary electric machine 10 via the inverter 20. The rotary electric machine 10 inputs and outputs electric power to and from the battery 40. At the time of power running, the electric power supplied from the battery 40 gives a propulsive force to the vehicle, and at the time of regeneration, the deceleration energy of the vehicle is used. It generates electricity and outputs electric power to the battery 40.

The battery monitoring device 100 includes a voltage sensor 30 as a voltage detection unit, a relay switch 31, a current sensor 32 as a current detection unit, and a BMU (Battery Management Unit) 50. The voltage sensor 30 detects the voltage between the terminals of each of the lithium ion storage batteries 41 constituting the battery 40, and detects the battery voltage VB which is the sum of the voltages between these terminals.

The current sensor 32 is provided on the connection line LC connecting the battery 40 and the inverter 20, and detects the charge / discharge current IS of the battery 40 flowing through the connection line LC. The relay switch 31 is provided between the battery 40 and the current sensor 32 on the connection line LC, and switches the connection state between the battery 40 and the rotary electric machine 10.

The BMU 50 includes a conversion unit 51 and a control unit 60. The conversion unit 51 converts the charge / discharge current IS output from the current sensor 32 into a first digital signal DS1 indicating the current value of the charge / discharge current IS. Specifically, the current sensor 32 outputs the sensor voltage VS corresponding to the detected charge / discharge current IS to the conversion unit 51, and the conversion unit 51 converts the sensor voltage VS into the first digital signal DS1. Further, the conversion unit 51 converts the battery voltage VB output from the voltage sensor 30 into a second digital signal DS2 indicating the voltage value of the battery voltage VB.

The control unit 60 stores the first digital signal DS1 and the second digital signal DS2 output from the conversion unit 51 in an internal RAM or the like. The control unit 60 calculates the SOC of the battery 40 based on the acquired first digital signal DS1. Further, the control unit 60 determines the overcharge / discharge state of the battery 40 based on the acquired second digital signal DS2.

The control unit 60 is a control device including a CPU, a ROM, a RAM, and the like. The control unit 60 is connected to the relay switch 31 via a relay drive unit (not shown), and outputs a control signal CS for switching the connection state of the relay switch 31 to the relay switch 31. Further, the control unit 60 is communicably connected to the travel control ECU 70 via the vehicle-mounted network interface 61, and outputs a command to control the rotary electric machine 10 based on the SOC of the battery 40 to the travel control ECU 70. As the in-vehicle network interface 61, a well-known interface such as CAN (Controller Area Network) or LIN (Local Interconnect Network) can be used. Based on a command from the control unit 60, the travel control ECU 70 controls the inverter 20 in order to control the control amount of the rotary electric machine 10 according to the command. The control amount is, for example, torque.

By the way, since the control unit 60 determines the overcharge / discharge state of the battery 40 based on the battery voltage VB, if the voltage sensor 30 is abnormal, the overcharge / discharge state of the battery 40 cannot be determined. In order to determine the over-discharged state of the battery 40 even when the voltage sensor 30 is abnormal, it is conceivable to determine the over-discharged state of the battery 40 based on the SOC calculated from the charge / discharge current IS.

In this case, since the SOC is calculated based on the integrated value of the charge / discharge current IS, the current range HI in which the current sensor 32 detects the charge / discharge current IS needs to be set widely so as to correspond to the wide range charge / discharge current IS. There is. The wider the current range HI of the current sensor 32, the worse the detection accuracy of the charge / discharge current IS. Therefore, in a state where the current range HI is set wider, the over-discharged state of the battery 40 is based on the integrated value of the charge / discharge current IS. However, the over-discharged state cannot be accurately determined.

Therefore, in the present embodiment, when the voltage sensor 30 is abnormal, the control unit 60 narrows the current range HI of the conversion unit 51 from the first range HI1 corresponding to the wide range charge / discharge current IS to the first range HI1. Switch to the second range HI2 (see FIG. 4). Specifically, the BMU 50 includes a first range setting unit CV1 for setting the first range HI1 and a second range setting unit CV2 for setting the second range HI2.

The first range setting unit CV1 includes a first DC power supply 52, a first operational amplifier 53, and first and second resistors R1 and R2. The first DC power supply 52 is connected to the ground voltage GND via the first and second resistors R1 and R2 connected in series, and the connection point between the first resistor R1 and the second resistor R2 is It is connected to one input terminal 53A of the first operational amplifier 53. The other input terminal 53B of the first operational amplifier 53 is connected to the control unit 60.

The first operational amplifier 53 outputs a voltage corresponding to the maximum current IJ (see FIG. 4) of the first range HI1 from the output terminal 55C to the current sensor 32 based on the voltage input to the input terminals 53A and 53B. In this embodiment, the first range HI1 is set to a range of zero current IE (see FIG. 4) symmetry. Therefore, the current sensor 32 can set the maximum current IJ and the minimum current IA (see FIG. 4) based on the voltage output from the first range setting unit CV1, thereby setting the first range HI1. Can be set.

The second range setting unit CV2 includes a second DC power supply 54, a second operational amplifier 55, and third and fourth resistors R3 and R4. The second DC power supply 54 is connected to the ground voltage GND via the third and fourth resistors R3 and R4 connected in series, and the connection point between the third resistor R3 and the fourth resistor R4 is It is connected to one input terminal 55A of the second operational amplifier 55. The other input terminal 55B of the second operational amplifier 55 is connected to the control unit 60. The second operational amplifier 55 outputs a voltage corresponding to the maximum current IH (see FIG. 4) of the second range HI2 from the output terminal 55C to the current sensor 32 based on the voltage input to the input terminals 55A and 55B.

The second operational amplifier 55 outputs a voltage corresponding to the maximum current IH (see FIG. 4) of the second range HI2 from the output terminal 55C to the current sensor 32 based on the voltage input to the input terminals 55A and 55B. In this embodiment, the second range HI2 is set to a range of zero current IE symmetry. Therefore, the current sensor 32 can set the maximum current IH and the minimum current IB (see FIG. 4) based on the voltage output from the second range setting unit CV2, whereby the second range HI2 can be set. Can be set.

When the current range HI of the conversion unit 51 is set to the first range HI1, the control unit 60 outputs the reference voltage VK to the first range setting unit CV1 and does not output the reference voltage VK to the second range setting unit CV2. To do so. Further, the control unit 60 designates the resolution BC corresponding to the first range HI1 to the conversion unit 51. The same applies to the case where the current range HI is set to the second range HI2. Then, when the current range HI is switched from the first range HI1 to the second range HI2, the control unit 60 changes the range setting unit CV that outputs the reference voltage VK from the first range setting unit CV1 to the second range setting unit CV2. At the same time, the resolution BC specified for the conversion unit 51 is switched to.

Then, when the voltage sensor 30 is abnormal, the control unit 60 performs a determination process for determining the overcharge / discharge state of the battery 40 based on the first digital signal DS1 converted in the second range HI2. Therefore, even when the voltage sensor 30 is abnormal, the accuracy of the overcharge / discharge determination can be improved.

FIG. 2 shows a flowchart of the determination process of the present embodiment. In this embodiment, a flowchart of the determination process at the time of regeneration of the rotary electric machine 10, that is, at the time of charging the battery 40 is shown. The control unit 60 repeatedly executes the determination process at predetermined intervals while the battery 40 is being charged.

When the determination process is started, first, in step S10, it is determined whether the voltage sensor 30 is abnormal. Abnormalities include irreversible abnormalities (failures) and reversible abnormalities. The abnormality of the voltage sensor 30 is, for example, a disconnection of the wiring connecting the voltage sensor 30 and the conversion unit 51, and when the battery voltage VB output from the voltage sensor 30 is smaller than the first determination voltage Vtg1, the voltage sensor 30 It is determined that 30 is abnormal. In this embodiment, the process of step S10 corresponds to the "abnormality determination unit".

If a negative determination is made in step S10, the restriction command RB is released in step S12. The restriction command RB will be described in detail later. In the following step S14, the current range HI of the conversion unit 51 is switched to the first range HI1. When it is determined in the previous determination process that the voltage sensor 30 is not abnormal, the limit command RB has already been released, and the current range HI of the conversion unit 51 has already been switched to the first range HI1. , Steps S12 and S14 may be omitted.

In step S16, the voltage sensor 30 is used to detect the battery voltage VB. In the following step S18, the average voltage VBA is calculated using the battery voltage VB detected in step S16. The average voltage VBA is the average value of the battery voltage VB detected in a specified period longer than twice a predetermined period.

In step S20, the overcharged state of the battery 40 is determined based on the average voltage VBA calculated in step S18. Specifically, it is determined whether the average voltage VBA is larger than the threshold voltage Vth. In the present embodiment, the threshold voltage Vth is set to the battery voltage VB corresponding to the overcharged state, for example, the battery voltage VB when the actual battery capacity PS of the battery 40 is 80%.

If the battery 40 is not in the overcharged state, a negative determination is made in step S20. In this case, in step S22, the relay switch 31 is maintained in the ON state, and the determination process is terminated. Further, when the battery 40 is in the overcharged state, a positive determination is made in step S20. In this case, in step S24, the relay switch 31 is switched to the off state, and the determination process is terminated.

On the other hand, if an affirmative determination is made in step S10, that is, if the voltage sensor 30 is determined to be abnormal, it is determined in step S26 whether the current sensor 32 is abnormal. The abnormality of the current sensor 32 is, for example, a disconnection of the wiring connecting the range setting units CV1 and CV2 and the current sensor 32, or the wiring connecting the current sensor 32 and the conversion unit 51, and the sensor output from the current sensor 32. When the voltage VS is smaller than the predetermined second determination voltage Vtg2, the current sensor 32 determines that the abnormality is present.

If an affirmative determination is made in step S26, the overcharged / discharged state of the battery 40 cannot be determined. Therefore, in step S48, the relay switch 31 is switched to the off state to end the determination process. On the other hand, if a negative determination is made in step S26, the restriction command RB is output to the travel control ECU 70 in step S28. Here, the limit command RB is a command for limiting the charge / discharge of the battery 40 so that the charge / discharge current IS becomes smaller than the predetermined current value IK. In the present embodiment, the predetermined current value IK is set to the maximum current IH in the second range HI2. By limiting the control amount of the rotary electric machine 10 according to the limit command RB, the charge / discharge current IS is controlled to be smaller than the predetermined current value IK. In the present embodiment, the process of step S28 corresponds to the “charge / discharge limiting unit”, and the predetermined current value IK corresponds to the “predetermined value”.

After the output of the limit command RB, in step S30, it is determined whether the charge / discharge current IS becomes smaller than the predetermined current value IK. If a negative determination is made in step S30, the current range HI of the conversion unit 51 is maintained in the first range HI1 in step S32. In this embodiment, the process of step S28 corresponds to the "current determination unit".

On the other hand, if an affirmative determination is made in step S30, that is, if it is determined that the charge / discharge current IS is smaller than the predetermined current value IK, in step S34, the current range HI of the conversion unit 51 is changed from the first range HI1 to the first. Switch to 2 range HI2.

When the current range HI is set in steps S32 and S34, the integrated value Σ used for determining the overcharged state of the battery 40 is calculated. Here, the integrated value Σ is an integrated value of the charge / discharge current IS, and more specifically, is an integrated value of the first digital signal DS1 converted in the current range HI set in steps S32 and S34.

Specifically, in step S36, it is determined whether the initial value Σs of the integrated value Σ has already been set. If a negative determination is made in step S36, the initial value Σs is set in step S38 based on the average voltage VBA calculated in the determination process before the previous time. The average voltage VBA is calculated when the voltage sensor 30 is determined not to be abnormal. Therefore, it can be said that the initial value Σs is set based on the average value of the battery voltage VB detected before the abnormality determination. In this embodiment, the process of step S38 corresponds to the "initial value setting unit".

If an affirmative determination is made in step S36, or if the initial value Σs is set in step S38, the charge / discharge current IS is detected using the current sensor 32 in step S40. In the following step S42, the integrated value Σ is calculated using the charge / discharge current IS detected in step S40. The integrated value Σ is calculated by integrating the charge / discharge current IS detected after setting the initial value Σs with the initial value Σs.

In step S44, the overcharged state of the battery 40 is determined based on the integrated value Σ calculated in step S42. Therefore, when the current range HI of the conversion unit 51 is switched to the second range HI2 in step S34, the overcharged state of the battery 40 is changed based on the first digital signal DS1 converted in the second range HI2. It is judged.

Specifically, it is determined whether the integrated value Σ is larger than the threshold integrated value Σth. In the present embodiment, the threshold integrated value Σth is set to the integrated value Σ corresponding to the overcharged state, and for example, when the actual battery capacity PS of the battery 40 is a value (75%) slightly smaller than 80%. It is set to the integrated value Σ of. In this embodiment, the process of step S44 corresponds to the "state determination unit".

If the battery 40 is not in the overcharged state, a negative determination is made in step S44. In this case, in step S46, the relay switch 31 is maintained in the ON state, and the determination process is terminated. Further, when the battery 40 is in the overcharged state, a positive determination is made in step S44. In this case, in step S48, the relay switch 31 is switched to the off state to end the determination process.

Subsequently, FIG. 3 shows an example of the determination process. FIG. 3 shows a process of determining an overcharged / discharged state of the battery 40 when the voltage sensor 30 becomes abnormal while charging the battery 40.

In FIG. 3, (A) shows the transition of the battery voltage VB, (B) shows the transition of the current sensor 32, (C) shows the transition of the limit command RB, and (D) shows the charge / discharge. The transition of the current IS is shown. Further, (E) shows the transition of the current range HI, (F) indicates the transition of the actual battery capacity PS, (G) indicates the transition of the integrated value Σ, and (H) is the relay switch 31. Shows the transition of the connection status of.

Further, in FIGS. 3 (G) and 3 (H), when the voltage sensor 30 is abnormal, the transition F1 of each value when the current range HI is switched from the first range HI1 to the second range HI2 is shown by a solid line. It is shown. Further, even when the voltage sensor 30 is abnormal, the transition F2 of each value when the current range HI is maintained in the first range HI1 is shown by a broken line.

In the illustrated example, the voltage sensor 30 becomes abnormal at time t1, and the battery voltage VB drops. After that, when the battery voltage VB becomes smaller than the first determination voltage Vtg1 at time t2, the control unit 60 determines that the voltage sensor 30 is abnormal, and the limit command RB is output. As a result, the charge / discharge current IS is limited, and the charge / discharge current IS decreases.

Further, the calculation of the integrated value Σ is started at time t2, and the overcharged state of the battery 40 is determined based on the calculated integrated value Σ. Specifically, the initial value Σs is set based on the average voltage VBA calculated before the abnormality determination of the voltage sensor 30, and the integrated value Σ is based on the first digital signal DS1 converted in the predetermined current range HI. Is calculated. In the illustrated example, at the time t2 when the limitation of the charge / discharge current IS is started, the current range HI is maintained in the first range HI1 because the charge / discharge current IS is larger than the predetermined current value IK. Therefore, at time t2, the integrated value Σ is calculated based on the first digital signal DS1 converted in the first range HI1, and the integrated value Σ starts to rise with the first slope θ1 with respect to the elapsed time.

After that, when the charge / discharge current IS drops below the predetermined current value IK at time t3, the current range HI is switched from the first range HI1 to the second range HI2, and becomes the first digital signal DS1 converted in the second range HI2. Based on this, the integrated value Σ is calculated.

FIG. 4 shows the relationship between the charge / discharge current IS and the first digital signal DS1. As shown in FIG. 4, the second range HI2 is set narrower than the first range HI1. On the other hand, the first range HI1 and the second range HI2 are converted into the first digital signal DS1 having the same gradation number of 2 KM. Therefore, the resolution BC of the current sensor 32 in the first range HI1 is smaller than the resolution BC in the second range HI2.

FIG. 5 shows the relationship between the resolution BC of the current sensor 32 and the detection error. As shown in FIG. 5, the detection error becomes smaller as the resolution BC becomes smaller. Therefore, by switching the second range HI2 to the first range HI1, the detection error of the current sensor 32 is suppressed.

In the example illustrated in FIG. 3, the current range HI is switched from the first range HI1 to the second range HI2 at time t3, and as a result of suppressing the detection error of the current sensor 32, the slope θ of the integrated value Σ becomes the second. It rises to the second slope θ2, which is larger than the slope θ1 by the slope difference Δθ. In the present embodiment, the slope θ of the integrated value Σ decreases with the elapsed time due to the decrease in the charge / discharge current IS. However, when the current range HI is switched from the first range HI1 to the second range HI2, the slope θ of the integrated value Σ at time t3 is tilted more than when it is maintained at the first slope θ1, that is, the first range HI1. It rises to the second slope θ2, which is larger by the difference Δθ.

As an example in which the second slope θ2 rises, there is a case shown in FIG. 6, for example. Specifically, when the current range HI is the first range HI1, the charge / discharge current IS from the current IX to the current IX is converted into a gradation value KX indicating the voltage value of the current IX, as shown by the broken line. Imagine a case. In this case, the current range HI is switched to the second range HI2, and as shown by the solid line, among the charge / discharge current IS from the current IX to the current IZ, the current IY to the current IZ between the current IX and the current IZ It is assumed that the charge / discharge current IS up to is switched so as to be converted into a gradation value KY indicating the voltage value of the current IY. In this case, since the first digital signal DS1 converted in the second range HI2 shows a voltage value equal to or higher than that of the first digital signal DS1 converted in the first range HI1, the slope θ of the integrated value Σ increases.

Even if the voltage sensor 30 is abnormal, as shown by the broken lines in FIGS. 3 (G) and 3 (H), if the current range HI is maintained in the first range HI1, the slope θ of the integrated value Σ becomes the first. It is maintained at 1 inclination θ1. In this case, when the integrated value Σ reaches the threshold integrated value Σth at the time t6 after the time t5 when the actual battery capacity PS of the battery 40 reaches 80%, the battery 40 is determined to be overcharged, and the relay switch 31 Is switched off. Since the battery 40 is determined to be overcharged after the actual battery capacity PS of the battery 40 is greater than 80%, the overcharged state cannot be accurately determined.

On the other hand, in the present embodiment, as shown by the solid lines in FIGS. 3 (G) and 3 (H), the current range HI is switched from the first range HI1 to the second range HI2 when the voltage sensor 30 is abnormal. In this case, when the integrated value Σ reaches the threshold integrated value Σth at the time t4 before the time t5, the battery 40 is determined to be overcharged, and the relay switch 31 is switched to the off state. Since the battery 40 is determined to be overcharged before the battery 40 is in the overcharged state, the overcharge determination can be accurately determined.

According to the present embodiment described in detail above, the following effects can be obtained.

In the battery monitoring device 100, the conversion unit 51 converts the charge / discharge current IS detected by the current sensor 32 into the first digital signal DS1 and converts the battery voltage VB detected by the voltage sensor 30 into the second digital signal DS2. To do. The control unit 60 of the BMU 50 calculates the SOC of the battery 40 based on the first digital signal DS1 and determines the overcharged / discharged state of the battery 40 based on the second digital signal DS2. When the voltage sensor 30 is determined to be abnormal, the overcharge / discharge state of the battery 40 is determined based on the first digital signal DS1. That is, when the voltage sensor 30 is abnormal, the overcharge / discharge determination of the battery 40 is performed based on the detection current of the current sensor 32 instead of the overcharge / discharge determination of the battery 40 based on the detection voltage of the voltage sensor 30. However, the current detection by the current sensor 32 has low accuracy in order to correspond to the charging / discharging current IS over a wide range, but the current range HI for detecting the charging / discharging current IS is widened, and the battery 40 is simply overcharged. The accuracy of overcharge / discharge determination cannot be guaranteed simply by switching the discharge determination parameter from voltage to current.

In this respect, in the present embodiment, when the voltage sensor 30 is abnormal, the current range HI of the conversion unit 51 is switched from the first range HI1 to the second range HI2, and the first digital signal DS1 converted in the second range HI2. The overcharged / discharged state of the battery 40 is determined based on the above. As a result, the accuracy of the overcharge / discharge determination can be improved when the voltage sensor 30 is abnormal.

On the other hand, if the charge / discharge current IS fluctuates beyond the second range HI2 after the current range HI of the conversion unit 51 is switched to the second range HI2, the charge / discharge current IS cannot be detected accurately and the SOC is calculated. As the accuracy deteriorates, the accuracy of overcharge / discharge determination deteriorates. In this respect, in the present embodiment, when the voltage sensor 30 is abnormal, the charge / discharge of the battery 40 is limited so that the charge / discharge current IS becomes smaller than the predetermined current value IK. Therefore, it is possible to suppress the charge / discharge current IS from fluctuating beyond the second range HI2 after the current range HI of the conversion unit 51 is switched to the second range HI2, and it is possible to improve the SOC calculation accuracy. The accuracy of overcharge / discharge determination can be improved.

-In particular, in the present embodiment, when it is determined that the charge / discharge current IS becomes smaller than the predetermined current value IK, the current range HI is switched to the second range HI2. Therefore, it is possible to surely suppress the charge / discharge current IS from fluctuating beyond the second range HI2 after the current range HI of the conversion unit 51 is switched to the second range HI2, and the SOC calculation accuracy and the overcharge / discharge determination can be determined. The accuracy of the above can be suitably increased.

-For example, if the charge / discharge current IS of the first range HI1 can be detected by the resolution BC in the second range HI2, it is not necessary to switch the current range HI. However, since the current sensor 32 having a wide current range HI and a small resolution BC is expensive, the use of such a current sensor 32 increases the manufacturing cost of the battery monitoring device 100. In this respect, in the present embodiment, the current sensor 32 having a wide current range HI and a large resolution BC and the current sensor 32 having a narrow current range HI and a small resolution BC are used in combination, so that the current sensor 32 is costly. It can be suppressed, and the manufacturing cost of the battery monitoring device 100 can be suppressed.

In the present embodiment, when the voltage sensor 30 is abnormal, the initial value Σs of the integrated value Σ is set based on the average voltage VBA which is the average value of the battery voltage VB detected before the abnormality determination. Therefore, the estimation accuracy of the integrated value Σ at the start of calculation can be improved, and the accuracy of overcharge / discharge determination can be improved.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 7 to 9, focusing on the differences from the first embodiment. In FIG. 7, the same processes as those shown in FIG. 2 above are given the same step numbers for convenience, and the description thereof will be omitted.

The present embodiment is different from the first embodiment in that the predetermined current value IK is variable. Therefore, in the determination process of the present embodiment, a predetermined current value IK is set when the charge / discharge of the battery 40 is restricted by the restriction command RB.

FIG. 7 shows a flowchart of the determination process according to the present embodiment. In the determination process of the present embodiment, if a negative determination is made in step S26, a predetermined current value IK is set based on the SOC of the battery 40 in step S50, and the process proceeds to step S28. In this embodiment, the process of step S50 corresponds to the "predetermined value setting unit".

FIG. 8 shows the relationship between the SOC and the predetermined current value IK. In FIG. 8, (A) shows the relationship between the SOC and the predetermined current value IK when the battery 40 is discharged, and (B) shows the relationship between the SOC and the predetermined current value IK when the battery 40 is charged.

As shown in FIG. 8A, a predetermined current value IK is set so that the smaller the SOC is, the smaller the value is when the battery 40 is discharged. Specifically, the SOC is set to the first predetermined current value IK1 from 0% to the first storage state SK1. From the first storage state SK1 to the second storage state SK2 in which the SOC is larger than the first storage state SK1, the second predetermined current value IK2 is set to be larger than the first predetermined current value IK1. From the second storage state SK2 to the third storage state SK3 in which the SOC is larger than the second storage state SK2, the third predetermined current value IK3 is set to be larger than the second predetermined current value IK2.

Further, as shown in FIG. 8B, a predetermined current value IK is set so that the larger the SOC, the smaller the value when the battery 40 is charged. Specifically, the SOC is set to the third predetermined current value IK3 from 0% to the first storage state SK1. The SOC is set to the second predetermined current value IK2 from the first storage state SK1 to the second storage state SK2. The SOC is set to the third predetermined current value IK3 from the second storage state SK2 to the third storage state SK3.

FIG. 9 shows the transition of the predetermined current value IK during charging of the battery 40. As shown in FIG. 9, in the present embodiment, the predetermined current value IK is not a constant value but is set variably based on the SOC. Specifically, in the period from time t15 to time t16, since the SOC rises beyond the second storage state SK2, the predetermined current value IK is set to the first predetermined current value IK1 which is relatively small. .. When charging the battery 40, when the SOC is large, it is preferable to increase the degree of limitation of the charging current as compared with the case where the SOC is small, and set the predetermined current value IK, which is the upper limit of the charging current, to be small. Is preferable.

On the other hand, in order to suppress the overcharged state, it is conceivable to set the predetermined current value IK to a small value regardless of the SOC. However, if the predetermined current value IK is set to a small value until the SOC is small, the charging current is excessively limited even though the possibility of overcharging is low, and the deceleration energy of the vehicle is sufficiently recovered. It may not be possible to charge the battery 40.

According to the present embodiment described above, the predetermined current value IK is set so that the larger the SOC, the smaller the value. Therefore, it is possible to preferably suppress the battery 40 from being overcharged while suppressing an excessive limitation of the charging current.

Further, in the present embodiment, when the SOC is small during discharge of the battery 40, it is preferable to increase the degree of limitation of the discharge current as compared with the case where the SOC is large, and a predetermined current which is an upper limit of the discharge current It is preferable to set the value IK small.

On the other hand, in order to suppress the over-discharged state, it is conceivable to set the predetermined current value IK to a small value regardless of the SOC. However, if the predetermined current value IK is set to a small value until the SOC is large, the discharge current is excessively limited even though the possibility of overcharging is low, and sufficient propulsive force cannot be given to the vehicle. For example, the discharge of the battery 40 is hindered.

According to this embodiment, the predetermined current value IK is set so that the smaller the SOC, the smaller the value. Therefore, it is possible to preferably suppress the battery 40 from being over-discharged while suppressing an excessive limitation of the discharge current.

(Third Embodiment)
Hereinafter, the third embodiment will be described with reference to FIGS. 10 to 14 focusing on the differences from the first embodiment. In FIG. 10, the same configurations as those shown in FIG. 1 above are designated by the same reference numerals for convenience, and the description thereof will be omitted.

The present embodiment is different from the first embodiment in that the battery monitoring device 100 includes a plurality of current sensors 32A to 32D. The current range HI of the first to fourth current sensors 32A to 32D is set to a constant value in advance, and the BMU 50 is not provided with a range setting unit CV for setting the current range HI.

The conversion unit 51 includes first to fourth current conversion units 56A to 56D corresponding to the first to fourth current sensors 32A to 32D, and a voltage conversion unit 58 corresponding to the voltage sensor 30. The first current conversion unit 56A converts the charge / discharge current IS output from the first current sensor 32A into a first digital signal DS1 indicating the current value of the charge / discharge current IS. Specifically, the first current sensor 32A outputs the sensor voltage VS corresponding to the detected charge / discharge current IS to the first current conversion unit 56A, and the first current conversion unit 56A outputs this sensor voltage VS to the first current conversion unit 56A. Convert to digital signal DS1. The same applies to the second to fourth current conversion units 56B to 56D. The voltage conversion unit 58 converts the battery voltage VB output from the voltage sensor 30 into a second digital signal DS2 indicating the voltage value of the battery voltage VB.

The control unit 60 selects one current sensor 32 from the first to fourth current sensors 32A to 32D, and detects the charge / discharge current IS using the selected current sensor 32. When the first current sensor 32A is selected, the control unit 60 outputs the reference voltage VK to the first current conversion unit 56A corresponding to the first current sensor 32A, and outputs the reference voltage VK to the other current conversion units 56B to 56D. Do not output. The same applies to the second to fourth current sensors 32A to 32D. Since the resolution BC corresponding to the first current sensor 32A is preset in the first current conversion unit 56A, the control unit 60 does not need to set the resolution BC.

FIG. 11 shows the relationship between the charge / discharge current IS and the first digital signal DS1 in the present embodiment. The first to fourth current sensors 32A to 32D each have a different current range HI, and the current range HI of the first current sensor 32A is the first range HI1. The current range HI of the second to fourth current sensors 32B to 32D is the first to third detection ranges HD1 to HD3, and the second range HI2 is configured by these first to third detection ranges HD1 to HD3. ing.

As shown in FIG. 11, the second range HI2 is set narrower than the first range HI1, and in the second range HI2, the current range HI of the first to third detection ranges HD1 to HD3 is narrower in this order. It is set. Therefore, in the present embodiment, the width of the second range HI2 can be changed by selecting the second to fourth current sensors 32B to 32D.

Specifically, the first range HI1 and the first to third detection ranges HD1 to HD3 are set in a range symmetrical with zero current IE (see FIG. 4), and the maximum currents IJ, IH, IG in each range are set. The IF is set to decrease in this order. Further, the minimum currents IA, IB, IC, and ID in each range are set to increase in this order. On the other hand, the first range HI1 and the first to third detection ranges HD1 to HD3 are converted into the first digital signal DS1 having the same gradation number of 2 KM. Therefore, the resolution BCs in the first range HI1 and the first to third detection ranges HD1 to HD3 are set to be smaller in this order.

As described above, in the present embodiment, the width of the second range HI2 can be changed. Therefore, in the determination process of the present embodiment, the detection range HD is set when the current range HI is switched from the first range HI1 to the second range HI2.

FIG. 12 shows a flowchart of the determination process according to the present embodiment. In the determination process of the present embodiment, if an affirmative determination is made in step S30, the detection range HD is set based on the charge / discharge current IS in step S60, and the process proceeds to step S34.

FIG. 13 shows the relationship between the charge / discharge current IS and the second range HI2. As shown in FIG. 13, the smaller the charge / discharge current IS, the narrower the detection range HD is set. Specifically, the charge / discharge current IS from zero current to the first determination current Itg1 is set in the third detection range HD3. The charge / discharge current IS from the first determination current Itg1 to the second determination current Itg2, which is larger than the first determination current Itg1, is set in the second detection range HD2. The charge / discharge current IS from the second determination current Itg2 to the predetermined current value IK is set in the first detection range HD1.

Subsequently, FIG. 14 shows an example of the determination process according to the present embodiment. FIG. 14 shows a process of switching the second range HI2 when the charging of the battery 40 is restricted after the voltage sensor 30 becomes abnormal during the charging of the battery 40.

In FIG. 14, (A) shows the transition of the charge / discharge current IS, (B) shows the transition of the second range HI2, and (C) shows the transition of the integrated value Σ of the charge / discharge current IS. In the illustrated example, the charge / discharge current IS is monotonically reduced after the charging of the battery 40 is limited.

In the illustrated example, when the charge / discharge current IS drops below the predetermined current value IK at time t21, the current range HI is switched from the first range HI1 to the second range HI2. Since the charge / discharge current IS is larger than the second determination current Itg2 at the time t21 when the second range HI2 is switched to, the first detection range HD1 of the second range HI2 is set. In the present embodiment, the slope θ of the integrated value Σ decreases with the elapsed time due to the decrease in the charge / discharge current IS. However, when the current range HI is switched from the first range HI1 to the first detection range HD1, the slope θ of the integrated value Σ at time t21 is maintained at the first slope θ1, that is, the first range HI1. It rises to the second slope θ2, which is larger by the first slope difference Δθ1.

After that, when the charge / discharge current IS becomes lower than the second determination current Itg2 at time t22, the current range HI is switched to the second detection range HD2. Along with this, at time t22, the second inclination θ2 increases by the second inclination difference Δθ2 as compared with the case where the second inclination θ2 is maintained in the first detection range HD1. Further, when the charge / discharge current IS becomes lower than the first determination current Itg1 at time t23, the current range HI is switched to the third detection range HD3. Along with this, at time t23, the second inclination θ2 increases by the third inclination difference Δθ3 as compared with the case where the second inclination θ2 is maintained in the second detection range HD2.

-According to the present embodiment described above, the width of the second range HI2 is narrowed as the charge / discharge current IS converges. As a result, the detection error of the current sensor 32 can be suppressed, and the accuracy of the overcharge / discharge determination can be improved.

-In the present embodiment, the slope θ of the integrated value Σ can be increased as the detection error in the current sensor 32 is suppressed. As a result, the time for the integrated value Σ to reach the threshold integrated value Σth can be shortened, and the battery 40 can be suitably suppressed from being overcharged.

(Other embodiments)
The present invention is not limited to the contents described in the above embodiments, and may be implemented as follows.

-In the above embodiment, an example of outputting the limit command RB when the voltage sensor 30 is abnormal is shown, but the present invention is not limited to this. For example, when the voltage sensor 30 is abnormal and the charge / discharge current IS is smaller than the predetermined current value IK, it is not necessary to output the limit command RB.

In the above embodiment, it is determined whether the charge / discharge current IS becomes smaller than the predetermined current value IK when the current range HI is switched from the first range HI1 to the second range HI2 after the output of the limit command RB. Although shown, it is not limited to this. For example, when the reference period TK (see FIG. 1), which is the maximum period required for the charge / discharge current IS to become smaller than the predetermined current value IK after the limit command RB is output, is known in advance. After this reference period, the current range HI may be switched to the second range HI2.

In this case, if the charge / discharge current IS is maintained in a state of being larger than the predetermined current value IK beyond the reference period, a higher-level ECU or the like (not shown) may be notified to that effect.

-In the above embodiment, an example is shown in which the initial value Σs of the integrated value Σ is set based on the average voltage VBA, but the present invention is not limited to this, and the initial value Σs may be set based on the SOC. , It may be set based on the battery voltage VB detected immediately before the abnormality determination.

-In the above embodiment, the conversion unit 51 is provided inside the BMU 50, but it may be provided outside the BMU 50.

-In the third embodiment, the battery monitoring device 100 includes four current sensors 32, but the present invention is not limited to this. For example, the battery monitoring device 100 may include two or three current sensors 32, or may include five or more current sensors 32.

In the above embodiment, there is an example in which a plurality of range setting units CV are provided as a configuration for realizing a current sensor 32 having a wide current range HI and a large resolution BC and a current sensor 32 having a narrow current range HI and a small resolution BC. An example in which a plurality of current sensors 32 are provided has been shown, but the present invention is not limited to this. For example, a plurality of range setting units CV may be provided and a plurality of current sensors 32 may be provided.

30 ... Voltage sensor, 32 ... Current sensor, 40 ... Battery, 51 ... Conversion unit, 60 ... Control unit, 100 ... Battery monitoring device, HI ... Current range, HI1 ... 1st range, HI2 ... 2nd range, IS ... Discharge current, VB ... Battery voltage.

Claims (6)

A current detector (32) that detects the charge / discharge current (IS) of the battery (40), and
A voltage detection unit (30) that detects the battery voltage (VB) of the battery, and
With a conversion unit (51) that converts the charge / discharge current into a first digital signal indicating the current value of the charge / discharge current, and converts the battery voltage into a second digital signal indicating the voltage value of the battery voltage. ,
The SOC is applied to the battery monitoring device (100) including the above, and the SOC indicating the charge state of the battery is calculated based on the first digital signal, and the overcharge / discharge state of the battery is determined based on the second digital signal. It is a control device that
An abnormality determination unit that determines an abnormality in the voltage detection unit,
When the abnormality determination unit determines that the abnormality is present, the current range in which the conversion unit converts the charge / discharge current into the first digital signal is narrower than the first range (HI1) to the first range. A control device including a state determination unit that switches to a second range (HI2) and determines an overcharge / discharge state of the battery based on the first digital signal converted in the second range. A charge / discharge limiting unit for limiting the charging / discharging of the battery so that the charging / discharging current becomes smaller than a predetermined value (IK) when the abnormality determining unit determines that the battery is abnormal is provided.
The control device according to claim 1, wherein the state determination unit switches the current range to the second range after the start of restriction by the charge / discharge limiting unit. A current determination unit for determining whether the charge / discharge current becomes smaller than the predetermined value after the start of restriction by the charge / discharge limiting unit is provided.
The control device according to claim 2, wherein the state determination unit switches the current range to the second range when the current determination unit determines that the value is smaller than the predetermined value. A predetermined value is set so that the larger the SOC is, the smaller the value is when the battery is charged, and the smaller the SOC is, the smaller the predetermined value is set when the battery is discharged. The control device according to claim 2 or 3, further comprising a value setting unit. The state determination unit can change the width of the second range, and any one of claims 2 to 4 makes the second range a narrower range as the charge / discharge current becomes smaller. The control device described in. The state determination unit determines the overcharge / discharge state of the battery using the integrated value (Σ) of the charge / discharge current.
It is provided with an initial value setting unit that sets an initial value of the integrated value based on the average value (VBA) of the battery voltage detected before the abnormality determination when the abnormality determination unit determines that the abnormality is present. The control device according to any one of claims 1 to 5.

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