JP7172857B2 - Control device - Google Patents

Description

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

As a control device of this type, for example, a device that includes a voltage detection unit and determines whether the battery is abnormal based on the battery voltage detected by the voltage detection unit is known, as disclosed in Patent Document 1 below. This device determines whether the battery is over-discharged based on the battery voltage. Further, the abnormality of the voltage detection unit is determined, and when the voltage detection unit is determined to be abnormal, the charging/discharging current of the battery is suppressed more than the normal time. As a result, the battery can be used continuously while the charge/discharge current of the battery is suppressed, and the influence on the system using the battery is reduced.

JP-A-2000-357541

However, if the voltage detector is abnormal, it is not possible to determine the over-discharged state of the battery based on the battery voltage. In order to determine the over-discharge 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 charging and discharging current of the battery detected by the current detection unit, It is also conceivable to determine the over-discharge state of the battery based on this SOC.

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

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device capable of improving the accuracy of overcharge/discharge determination of a battery even when a voltage detector is abnormal. It is in.

A first means for solving the above problems includes a current detection section for detecting a charging/discharging current of a battery, a voltage detecting section for detecting a battery voltage of the battery, and a a conversion unit that converts the battery voltage into a first digital signal that indicates a current value, and that converts the battery voltage into a second digital signal that indicates the voltage value of the battery voltage; A control device for calculating an SOC indicating a state of charge of the battery based on the signal and determining an overcharge/discharge state of the battery based on the second digital signal, the control device determining an abnormality of the voltage detection unit. and a current range in which the conversion unit converts the charge/discharge current into the first digital signal when the abnormality determination unit determines that there is an abnormality, from a first range to the first range. a state determination unit that switches to a narrower second range and determines an overcharge/discharge state of the battery based on the first digital signal converted in the second range.

In the battery monitoring device, the converter converts the charge/discharge current detected by the current detector into a first digital signal, and converts the battery voltage detected by the voltage detector into a second digital signal. A control device of the battery monitoring device calculates the SOC of the battery based on the first digital signal and determines the overcharge/discharge state of the battery based on the second digital signal. Further, when it is determined that the voltage detection unit is abnormal, the overcharge/discharge state of the battery is determined based on the first digital signal. In other words, when the voltage detection unit is abnormal, overcharge/discharge determination of the battery is performed based on the current detected by the current detection unit instead of overcharge/discharge determination based on the voltage detected by the voltage detection unit. However, the current detection by the current detection unit has low accuracy in order to handle a wide range of charging and discharging currents, but it widens the current range for detecting charging and discharging currents. Accuracy of overcharge/discharge determination cannot be ensured 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 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 charge/discharge of the battery so that the charge/discharge current becomes smaller than a predetermined value when the abnormality determination unit determines that there is an abnormality, The state determination unit switches the current range to the second range after the charge/discharge limiter starts limiting.

If the charge/discharge current fluctuates beyond the second range after the current range of the converter is switched to the second range, the charge/discharge current cannot be accurately detected, and the accuracy of overcharge/discharge determination deteriorates. In this regard, in the above configuration, charging and discharging of the battery is restricted so that the charging and discharging current becomes smaller than a predetermined value when the voltage detecting section is abnormal. Therefore, after the current range of the conversion unit is switched to the second range, it is possible to suppress the charge/discharge current from fluctuating beyond the second range, thereby improving the accuracy of overcharge/discharge determination.

The third means includes a current determination unit that determines whether the charge/discharge current has become smaller than the predetermined value after the charge/discharge limit unit starts limiting, and the state determination unit determines whether the current determination unit When it is determined that the current is smaller than the predetermined value, the current range is switched to the second range.

According to the above configuration, the current range is switched to the second range when it is determined that the charging/discharging current is smaller than the predetermined value. Therefore, after the current range of the conversion unit is switched to the second range, the charge/discharge current can be reliably suppressed from fluctuating beyond the second range, and the accuracy of overcharge/discharge determination can be preferably improved.

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

During charging of the battery, when the SOC is large, it is preferable to limit the charging current to a greater extent than when the SOC is small, and it is preferable to set the predetermined value, which is the upper limit of the charging current, to a small value. On the other hand, if the predetermined value is set to a small value even when the SOC is small, the charging current will be excessively limited, and charging of the battery will be hindered. In this regard, in the above configuration, the predetermined value is set so that the larger the SOC, the smaller the value. Therefore, it is possible to suitably prevent the battery from being overcharged while suppressing the excessive limitation of the charging current.

Further, when the SOC is small during battery discharge, it is preferable to limit the charging current to a greater extent than when the SOC is large, and the predetermined value, which is the upper limit of the charging current, may be set smaller. preferable. On the other hand, if the predetermined value is set to a small value even when the SOC is large, the discharge current will be excessively limited, which will interfere with the discharge of the battery. In this regard, in the above configuration, the predetermined value is set so that the smaller the SOC, the smaller the value. Therefore, it is possible to prevent the battery from being over-discharged while suppressing excessive restriction of the discharge current.

In the fifth means, the state determination section can change the width of the second range, and the second range is narrowed as the charge/discharge current decreases.

According to the above configuration, by narrowing the width of the second range as the charge/discharge current converges, it is possible to improve the accuracy of overcharge/discharge determination.

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

According to the above configuration, it is possible to improve the estimation accuracy of the integrated value at the start of current integration, and to enhance the accuracy of overcharge/discharge determination.

1 is an overall configuration diagram of a battery monitoring device according to a first embodiment; FIG. 4 is a flowchart of determination processing according to the first embodiment; FIG. 5 is a diagram showing a process of determining an overcharged state when the voltage sensor is abnormal; The figure which shows the relationship between the charging/discharging current which concerns on 1st Embodiment, and a 1st digital signal. FIG. 4 is a diagram showing the relationship between the resolution of a current sensor and detection error; The figure which shows the conversion process of the charging/discharging current by a conversion part. 9 is a flowchart of determination processing according to the second embodiment; FIG. 4 is a diagram showing the relationship between SOC and a predetermined current value; FIG. 4 is a diagram showing transition of a predetermined current value during charging of a battery; The whole block diagram of the battery monitoring apparatus which concerns on 3rd Embodiment. The figure which shows the relationship between the charging/discharging current which concerns on 3rd Embodiment, and a 1st digital signal. 10 is a flowchart of determination processing according to the third embodiment; The figure which shows the relationship between a charging/discharging current and a 2nd range. The figure which shows the switching process of the 2nd range in control processing.

(First embodiment)
A first embodiment in which a control device according to the present invention is applied to an in-vehicle battery monitoring device 100 will be described below 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 state of charge (SOC) indicating the state of charge of the battery 40 and the charge/discharge state. The battery 40 is a chargeable/dischargeable storage battery, and specifically, an assembled battery in which a plurality of lithium ion storage batteries 41 are connected in series. Note that the battery 40 may be another type of storage battery.

Battery 40 is connected to rotating electric machine 10 via inverter 20 . The rotating electrical machine 10 inputs and outputs electric power to and from the battery 40. During power running, the electric power supplied from the battery 40 provides propulsion to the vehicle, and during regeneration, the vehicle deceleration energy is used. It generates power and outputs power to the battery 40 .

The battery monitoring device 100 includes a voltage sensor 30 as a voltage detector, a relay switch 31, a current sensor 32 as a current detector, and a BMU (Battery Management Unit) 50. The voltage sensor 30 detects the terminal voltages of the lithium-ion storage batteries 41 that constitute the battery 40, and detects the battery voltage VB that is the sum of these terminal voltages.

The current sensor 32 is provided on a connection line LC that connects the battery 40 and the inverter 20, and detects a charging/discharging current IS of the battery 40 flowing through the connection line LC. Relay switch 31 is provided between battery 40 and current sensor 32 on connection line LC, and switches the connection state between battery 40 and rotary electric machine 10 .

The BMU 50 includes a conversion section 51 and a control section 60 . The conversion unit 51 converts the charging/discharging current IS output from the current sensor 32 into a first digital signal DS1 indicating the current value of the charging/discharging current IS. Specifically, the current sensor 32 outputs a sensor voltage VS corresponding to the detected charge/discharge current IS to the converter 51, and the converter 51 converts the sensor voltage VS into a 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 obtained first digital signal DS1. Also, the control unit 60 determines the overcharge/discharge state of the battery 40 based on the obtained 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 driving unit (not shown), and outputs a control signal CS for switching the connection state of the relay switch 31 to the relay switch 31 . The control unit 60 is also communicably connected to a travel control ECU 70 via an in-vehicle network interface 61 , and outputs commands for controlling 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, for example, a known interface such as CAN (Controller Area Network) or LIN (Local Interconnect Network) can be used. The travel control ECU 70 controls the inverter 20 based on the command from the control unit 60 so as to control the control amount of the rotating electric machine 10 according to the command. The controlled variable 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, it cannot determine the overcharge/discharge state of the battery 40 when the voltage sensor 30 is abnormal. In order to determine the overdischarged state of battery 40 even when voltage sensor 30 is abnormal, it is conceivable to determine the overdischarged state of battery 40 based on the SOC calculated from charge/discharge current IS.

In this case, since the SOC is calculated based on the integrated value of the charging/discharging current IS, the current range HI in which the current sensor 32 detects the charging/discharging current IS needs to be set wide so as to correspond to a wide range of charging/discharging 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. , the overdischarged state cannot be accurately determined.

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

The first range setting section 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 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 section 60 .

The first operational amplifier 53 outputs a voltage corresponding to the maximum current IJ (see FIG. 4) in the first range HI1 from the output terminal 55C to the current sensor 32 based on the voltages input to the input terminals 53A and 53B. In this embodiment, the first range HI1 is set to a range symmetrical to the zero current IE (see FIG. 4). 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 to can be set.

The second range setting section 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 section 60 . The second operational amplifier 55 outputs a voltage corresponding to the maximum current IH (see FIG. 4) in the second range HI2 from the output terminal 55C to the current sensor 32 based on the voltages 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) in the second range HI2 from the output terminal 55C to the current sensor 32 based on the voltages input to the input terminals 55A and 55B. In this embodiment, the second range HI2 is set to a zero current IE symmetrical range. 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, thereby setting the second range HI2. can be set.

When setting the current range HI of the conversion unit 51 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. make it The control unit 60 also 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. When switching the current range HI from the first range HI1 to the second range HI2, the control unit 60 switches the range setting unit CV for outputting the reference voltage VK from the first range setting unit CV1 to the second range setting unit CV2. , and the resolution BC specified for the conversion unit 51 is also switched.

Then, when the voltage sensor 30 is abnormal, the control unit 60 performs determination processing 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 overcharge/discharge determination can be improved.

FIG. 2 shows a flowchart of the determination processing of this embodiment. In the present embodiment, a flowchart of determination processing during regeneration of the rotating electric machine 10, that is, during charging of the battery 40 is shown. The control unit 60 repeats the determination process every predetermined period 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. An abnormality of the voltage sensor 30 is, for example, disconnection of wiring connecting the voltage sensor 30 and the conversion unit 51. When the battery voltage VB output from the voltage sensor 30 is lower than the first determination voltage Vtg1, the voltage sensor 30 is determined to be abnormal. In addition, in this embodiment, the process of step S10 corresponds to an "abnormality determination part."

If a negative determination is made in step S10, the restriction command RB is canceled in step S12. Note that the restriction command RB will be described later in detail. In subsequent step S14, the current range HI of the conversion unit 51 is switched to the first range HI1. In the previous determination process, if it was determined that the voltage sensor 30 was not abnormal, the limit command RB had already been canceled, and the current range HI of the conversion unit 51 had already been switched to the first range HI1. , steps S12 and S14 may be omitted.

In step S16, voltage sensor 30 is used to detect battery voltage VB. In subsequent step S18, average voltage VBA is calculated using battery voltage VB detected in step S16. The average voltage VBA is the average value of the battery voltages VB detected during a specified period longer than twice the specified 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 higher than the threshold voltage Vth. In this 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 overcharged, 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 ends. Moreover, when the battery 40 is in an overcharged state, an affirmative 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 ends.

On the other hand, if an affirmative determination is made in step S10, that is, if it is determined that the voltage sensor 30 is abnormal, it is determined in step S26 whether the current sensor 32 is abnormal. An abnormality of the current sensor 32 is, for example, disconnection of wiring connecting the range setting units CV1, CV2 and the current sensor 32, or disconnection of wiring connecting the current sensor 32 and the conversion unit 51. If the voltage VS is lower than the predetermined second determination voltage Vtg2, it is determined that the current sensor 32 is abnormal.

If an affirmative determination is made in step S26, the overcharge/discharge state of the battery 40 cannot be determined, so in step S48 the relay switch 31 is switched to the off state, and the determination process ends. On the other hand, if a negative determination is made in step S26, a restriction command RB is output to the travel control ECU 70 in step S28. Here, limit command RB is a command for limiting charging and discharging of battery 40 so that charging/discharging current IS becomes smaller than predetermined current value IK. In this 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 rotating electrical machine 10 according to the limit command RB, the charging/discharging 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 limiter", and the predetermined current value IK corresponds to the "predetermined value".

After outputting the limit command RB, in step S30, it is determined whether the charging/discharging current IS has become 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 at the first range HI1 in step S32. In addition, in this embodiment, the process of step S28 corresponds to a "current determination part."

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 has become 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 2 Switch to range HI2.

After the current range HI is set in steps S32 and S34, an integrated value Σ used to determine whether the battery 40 is in an overcharged state is calculated. Here, the integrated value Σ is the integrated value of the charge/discharge current IS, and more specifically, the 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 or not the initial value Σs of the integrated value Σ has already been set. If a negative determination is made in step S36, an initial value Σs is set in step S38 based on the average voltage VBA calculated in the previous determination process. Note that the average voltage VBA is calculated when it is determined that the voltage sensor 30 is not 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. It should be noted that in the present 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 current sensor 32 is used to detect the charging/discharging current IS in step S40. In subsequent step S42, the integrated value Σ is calculated using the charging/discharging current IS detected in step S40. The integrated value Σ is calculated by integrating the charge/discharge current IS detected after the initial value Σs is set to the initial value Σs.

In step S44, the overcharged state of 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 determined based on the first digital signal DS1 converted in the second range HI2. be judged.

Specifically, it is determined whether the integrated value Σ is greater than the threshold integrated value Σth. In this embodiment, the threshold integrated value Σth is set to an integrated value Σ corresponding to the overcharged state. For example, when the actual battery capacity PS of the battery 40 is slightly smaller than 80% (75%) is set to the integrated value Σ. In addition, in this embodiment, the process of step S44 corresponds to a "state determination part."

If the battery 40 is not overcharged, 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 ends. Moreover, when the battery 40 is in an overcharged state, an affirmative determination is made in step S44. In this case, in step S48, the relay switch 31 is turned off, and the determination process ends.

Next, FIG. 3 shows an example of determination processing. FIG. 3 shows the process of determining the overcharge/discharge state of the battery 40 when the voltage sensor 30 becomes abnormal while the battery 40 is being charged.

In FIG. 3, (A) shows changes in the battery voltage VB, (B) shows changes in the current sensor 32, (C) shows changes in the limit command RB, and (D) shows charge/discharge. It shows the transition of the current IS. In addition, (E) indicates 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

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

In the illustrated example, voltage sensor 30 becomes abnormal at time t1, and battery voltage VB drops. Thereafter, when battery voltage VB becomes lower than first determination voltage Vtg1 at time t2, control unit 60 determines that voltage sensor 30 is abnormal, and outputs restriction command RB. As a result, the charging/discharging current IS is limited, and the charging/discharging current IS decreases.

At time t2, the calculation of integrated value Σ is started, and the overcharged state of 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 calculated. In the illustrated example, the charging/discharging current IS is greater than the predetermined current value IK at the time t2 when the limitation of the charging/discharging current IS is started, so the current range HI is maintained at the first range HI1. 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 increasing with the first slope θ1 with respect to the elapsed time.

After that, when the charging/discharging current IS becomes lower than 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 the first digital signal DS1 converted in the second range HI2 is obtained. 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 2KM. 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 smaller the resolution BC, the smaller the detection error. Therefore, the detection error of the current sensor 32 is suppressed by switching the second range HI2 to the first range HI1.

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 It rises to a second slope θ2 that is greater than the first slope θ1 by the slope difference Δθ. In this embodiment, the slope θ of the integrated value Σ decreases with the passage of time due to the decrease in the charge/discharge current IS. However, by switching the current range HI from the first range HI1 to the second range HI2, the slope θ of the integrated value Σ at the time t3 is the first slope θ1, that is, the slope is lower than when the first range HI1 is maintained. It rises to the second slope θ2 that is larger by the difference Δθ.

FIG. 6 shows an example where the second slope θ2 increases. Specifically, when the current range HI is the first range HI1, the charge/discharge current IS from the current IX to the current IZ is converted into the gradation value KX indicating the voltage value of the current IX, as indicated by the dashed line. It is assumed that In this case, the current range HI is switched to the second range HI2. It is assumed that the charging/discharging current IS up to is switched to be converted into the 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 indicates a voltage value equal to or higher than 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 dashed lines in FIGS. 1 inclination θ1 is maintained. In this case, the integrated value Σ reaches the threshold integrated value Σth at time t6 after the time t5 when the actual battery capacity PS of the battery 40 reaches 80%, and the battery 40 is overcharged. is switched off. Since the battery 40 is determined to be overcharged after the actual battery capacity PS of the battery 40 has reached an overcharged state greater than 80%, the overcharged state cannot be accurately determined.

On the other hand, in the present embodiment, as indicated by solid lines in FIGS. 3G and 3H, 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 time t4 before time t5, it is determined that the battery 40 is overcharged, and the relay switch 31 is turned off. Since the battery 40 is determined to be overcharged before the battery 40 reaches the overcharged state, it is possible to accurately determine the overcharge.

According to this embodiment detailed above, the following effects can be obtained.

In the battery monitoring device 100, the converter 51 converts the charging/discharging current IS detected by the current sensor 32 into a first digital signal DS1, and converts the battery voltage VB detected by the voltage sensor 30 into a second digital signal DS2. 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 overcharge/discharge state of the battery 40 based on the second digital signal DS2. Further, when it is determined that the voltage sensor 30 is abnormal, the overcharge/discharge state of the battery 40 is determined based on the first digital signal DS1. That is, when voltage sensor 30 is abnormal, overcharge/discharge determination of battery 40 is performed based on the current detected by current sensor 32 instead of overcharge/discharge determination of battery 40 based on the voltage detected by voltage sensor 30 . However, the current detection by the current sensor 32 has low accuracy in order to correspond to a wide range of charging/discharging current IS, but widens the current range HI for detecting the charging/discharging current IS. Merely switching the discharge determination parameter from voltage to current cannot guarantee the accuracy of overcharge/discharge determination.

In this regard, 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 overcharge/discharge state of the battery 40 is determined based on. As a result, when the voltage sensor 30 is abnormal, it is possible to improve the accuracy of overcharge/discharge determination.

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 accurately detected, and the SOC cannot be calculated. Accuracy deteriorates, and the accuracy of overcharge/discharge determination also deteriorates. In this regard, in the present embodiment, when the voltage sensor 30 is abnormal, the charge/discharge of the battery 40 is restricted so that the charge/discharge current IS becomes smaller than the predetermined current value IK. Therefore, after the current range HI of the conversion unit 51 is switched to the second range HI2, it is possible to suppress the charge/discharge current IS from fluctuating beyond the second range HI2, thereby improving the calculation accuracy of the SOC. Accuracy of overcharge/discharge determination can be improved.

Especially in the present embodiment, when it is determined that the charging/discharging current IS has become smaller than the predetermined current value IK, the current range HI is switched to the second range HI2. Therefore, after the current range HI of the conversion unit 51 is switched to the second range HI2, it is possible to reliably suppress the charge/discharge current IS from fluctuating beyond the second range HI2. can be preferably increased in accuracy.

- For example, if the charge/discharge current IS in the first range HI1 can be detected with the resolution BC in the second range HI2, there is no need to switch the current range HI. However, since the current sensor 32 with a wide current range HI and a small resolution BC is expensive, using such a current sensor 32 increases the manufacturing cost of the battery monitoring device 100 . In this regard, in the present embodiment, the current sensor 32 with a wide current range HI and a large resolution BC and the current sensor 32 with a narrow current range HI and a small resolution BC are used in combination. can be suppressed, and the manufacturing cost of the battery monitoring device 100 can be suppressed.

In this 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 that is the average value of the battery voltages VB detected before the abnormality determination. Therefore, it is possible to improve the accuracy of estimating the integrated value Σ at the start of calculation, and to improve the accuracy of overcharge/discharge determination.

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

This embodiment differs from the first embodiment in that the predetermined current value IK is variable. Therefore, in the determination process of the present embodiment, the predetermined current value IK is set when the charging/discharging of the battery 40 is restricted by the restriction command RB.

FIG. 7 shows a flowchart of determination processing according to the present embodiment. In the determination process of the present embodiment, if a negative determination is made in step S26, in step S50 a predetermined current value IK is set based on the SOC of the battery 40, and the process proceeds to step S28. It should be noted that in the present 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. 8A shows the relationship between the SOC and the predetermined current value IK when the battery 40 is discharged, and FIG. 8B shows the relationship between the SOC and the predetermined current value IK when the battery 40 is charged.

As shown in FIG. 8A, when the battery 40 is discharged, the predetermined current value IK is set so as to decrease as the SOC decreases. Specifically, when the SOC is from 0% to the first state of charge SK1, the first predetermined current value IK1 is set. From the first state of charge SK1 to the second state of charge SK2 in which the SOC is greater than the first state of charge SK1, the SOC is set to a second predetermined current value IK2 greater than the first predetermined current value IK1. From the second state of charge SK2 to the third state of charge SK3 in which the SOC is greater than the second state of charge SK2, the SOC is set to a third predetermined current value IK3 greater than the second predetermined current value IK2.

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

FIG. 9 shows the transition of the predetermined current value IK while the battery 40 is being charged. As shown in FIG. 9, in this embodiment, the predetermined current value IK is set not as a constant value but as variable based on the SOC. Specifically, in the period from time t15 to time t16, the SOC rises beyond the second state of charge SK2, so the predetermined current value IK is set to a relatively small first predetermined current value IK1. . When charging the battery 40, when the SOC is high, it is preferable to limit the charging current to a greater extent than when the SOC is low, and the predetermined current value IK, which is the upper limit of the charging current, is set small. is preferred.

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 even when 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. charging of the battery 40 is hindered.

According to the present embodiment described above, the predetermined current value IK is set so as to decrease as the SOC increases. Therefore, it is possible to suitably prevent the battery 40 from being overcharged while suppressing excessive limitation of the charging current.

Further, in the present embodiment, when the SOC is small during discharging of the battery 40, it is preferable to increase the degree of limitation of the discharge current compared to when the SOC is large. It is preferable to set the value IK small.

On the other hand, in order to suppress the overdischarge 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 even when the SOC is large, the discharge current is excessively limited even though the possibility of overcharging is low, and sufficient propulsion cannot be applied to the vehicle. For example, the discharge of the battery 40 is hindered.

According to this embodiment, the predetermined current value IK is set such that the smaller the SOC, the smaller the value. Therefore, it is possible to suitably prevent the battery 40 from being over-discharged while suppressing excessive restriction of the discharge current.

(Third Embodiment)
The third embodiment will be described below with reference to FIGS. 10 to 14, focusing on differences from the first embodiment. In FIG. 10, for convenience, the same components as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

This embodiment differs from the first embodiment in that the battery monitoring device 100 includes a plurality of current sensors 32A-32D. The current ranges HI of the first to fourth current sensors 32A to 32D are preset to constant values, and the BMU 50 is not provided with the range setting section CV for setting the current ranges HI.

The conversion section 51 includes first to fourth current conversion sections 56A to 56D corresponding to the first to fourth current sensors 32A to 32D and a voltage conversion section 58 corresponding to the voltage sensor 30. FIG. The first current converter 56A converts the charging/discharging current IS output from the first current sensor 32A into a first digital signal DS1 indicating the current value of the charging/discharging current IS. Specifically, the first current sensor 32A outputs a 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 converts the sensor voltage VS to the first Convert to digital signal DS1. The same applies to the second to fourth current converters 56B to 56D. The voltage converter 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 uses the selected current sensor 32 to detect the charging/discharging current IS. When selecting the first current sensor 32A, 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. will not be output. The same applies to the second to fourth current sensors 32A-32D. In addition, since the resolution BC corresponding to the first current sensor 32A is preset in the first current converter 56A, the controller 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 this embodiment. The first to fourth current sensors 32A to 32D have different current ranges HI, and the current range HI of the first current sensor 32A is the first range HI1. The current ranges HI of the second to fourth current sensors 32B to 32D are the first to third detection ranges HD1 to HD3, and the first to third detection ranges HD1 to HD3 constitute the second range HI2. ing.

As shown in FIG. 11, the second range HI2 is set narrower than the first range HI1. is set. Therefore, in this 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 symmetrically with respect to the zero current IE (see FIG. 4), and the maximum currents IJ, IH, IG, IF is set to decrease in this order. Also, 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 2KM. Therefore, the resolution BC in the first range HI1 and the first to third detection ranges HD1 to HD3 is set to decrease in this order.

Thus, in this 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 switching the current range HI from the first range HI1 to the second range HI2.

FIG. 12 shows a flowchart of determination processing according to the present embodiment. In the determination process of the present embodiment, if an affirmative determination is made in step S30, in step S60 the detection range HD is set based on the charge/discharge current IS, 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 charging/discharging current IS, the narrower the detection range HD is set. Specifically, the charge/discharge current IS is set to the third detection range HD3 from zero current to the first determination current Itg1. A second detection range HD2 is set between the first determination current Itg1 and the second determination current Itg2 in which the charging/discharging current IS is larger than the first determination current Itg1. The charge/discharge current IS is set to the first detection range HD1 from the second determination current Itg2 to the predetermined current value IK.

Next, FIG. 14 shows an example of determination processing according to this embodiment. FIG. 14 shows the process of switching the second range HI2 when the charging of the battery 40 is restricted after the voltage sensor 30 becomes abnormal while the battery 40 is being charged.

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

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

After that, when the charging/discharging 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. Accordingly, at time t22, the second slope θ2 increases by the second slope difference Δθ2 from the case where the first detection range HD1 is maintained. 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. Accordingly, at time t23, the second slope θ2 increases by the third slope difference Δθ3 from the case where the second detection range HD2 is maintained.

- According to this 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 overcharge/discharge determination can be improved.

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

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

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

In the above embodiment, when the current range HI is switched from the first range HI1 to the second range HI2 after the limit command RB is output, it is determined whether the charge/discharge current IS has become smaller than the predetermined current value IK. However, it is not limited to this. For example, if 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 charging/discharging current IS is maintained to be greater than the predetermined current value IK beyond the reference period, a not-shown host ECU or the like may be notified of this fact.

In the above embodiment, the initial value Σs of the integrated value Σ is set based on the average voltage VBA. However, the initial value Σs may be set based on the SOC. , may be set based on the battery voltage VB detected immediately before the abnormality determination.

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

- Although the battery monitoring apparatus 100 showed the example provided with the four current sensors 32 in the said 3rd Embodiment, it is not restricted to this. For example, the battery monitoring device 100 may have two or three current sensors 32, or five or more current sensors 32. FIG.

In the above embodiment, as a configuration for realizing the current sensor 32 with a wide current range HI and a large resolution BC and the current sensor 32 with a narrow current range HI and a small resolution BC, a plurality of range setting units CV are provided, Although an example in which a plurality of current sensors 32 are provided has been shown, the present invention is not limited to this. For example, a plurality of range setting units CV 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... First range HI2... Second range IS... Charging Discharge current, VB...battery voltage.

Claims (6)

a current detection unit (32) that detects the charge/discharge current (IS) of the battery (40);
a voltage detection unit (30) for detecting the battery voltage (VB) of the battery;
a conversion unit (51) for converting the charging/discharging current into a first digital signal indicating the current value of the charging/discharging current and converting the battery voltage into a second digital signal indicating the voltage value of the battery voltage; ,
and calculates an SOC indicating the state of charge of the battery based on the first digital signal, and determines the overcharge/discharge state of the battery based on the second digital signal A control device for
The current detection unit has a plurality of current sensors (32A to 32D), each of which detects the charge/discharge current and has a different current range converted into the first digital signal,
The conversion unit has a current conversion unit (56A to 56D) provided for each of the current sensors, and each current conversion unit converts the charge/discharge current corresponding to the predetermined output range of the first digital signal. a conversion range is determined according to the current range of each current sensor;
an abnormality determination unit that determines an abnormality of the voltage detection unit;
When the abnormality determination unit determines that there is an abnormality, switching between the current sensors in the current detection unit and the current conversion units in the conversion unit changes the conversion range in the conversion unit to a first A state determination unit that switches from the range (HI1) to a second range (HI2) that is narrower than the first range, and determines an overcharge/discharge state of the battery based on the first digital signal converted in the second range. When,
A control device comprising: a charging/discharging limiting unit that limits charging/discharging of the battery so that the charging/discharging current becomes smaller than a predetermined value (IK) when the abnormality determination unit determines that there is an abnormality;
The control device according to claim 1, wherein the state determination unit switches the conversion range to the second range after the charging/discharging limiter starts limiting. A current determination unit that determines whether the charge/discharge current has become smaller than the predetermined value after the start of limitation by the charge/discharge limiter,
The control device according to claim 2, wherein the state determination unit switches the conversion range to the second range when the current determination unit determines that the current is smaller than the predetermined value. The predetermined value is set so as to decrease as the SOC increases during charging of the battery, and to decrease as the SOC decreases during discharging of the battery. 4. The control device according to claim 2, further comprising a value setting section. 5. Any one of claims 2 to 4, wherein the state determination section is capable of changing the width of the second range, and the width of the second range becomes narrower as the charge/discharge current decreases. The control device according to . The state determination unit determines an overcharge/discharge state of the battery using the integrated value (Σ) of the charge/discharge current,
An initial value setting unit for setting an initial value of the integrated value based on an average value (VBA) of the battery voltage detected before the abnormality determination when the abnormality determination unit determines that there is an abnormality. Control device according to any one of claims 1 to 5.

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