JP2020169898A - Control device - Google Patents

Abstract

To provide a control device capable of preventing an excessive increase in power storage error even during charging and discharging of a power storage device.SOLUTION: A control device for controlling charging and discharging of a power storage device is provided, comprising: a state computation unit configured to compute SOC indicative of a power storage state of the power storage device; an error computation unit configured to compute power storage error of SOC such that the error increases over time during charging and discharging of the power storage device; and an error reset unit configured to reset the power storage error when the power storage error is greater than a given error threshold.SELECTED DRAWING: Figure 4

Description

The present invention relates to a control device that controls a power storage device.

Conventionally, there is known a control device that calculates a power storage state (SOC) during charging / discharging of the power storage device and controls the power storage device based on the calculated SOC (for example, Patent Document 1). According to this control device, it is possible to prevent the power storage device from being overcharged or overdischarged and to protect the power storage device.

Japanese Unexamined Patent Publication No. 2013-217819

However, since the SOC calculated during charging / discharging is calculated using, for example, the time integral value of the current acquired during charging / discharging of the power storage device, this SOC corresponds to the integration of the current detection error. Accumulation error is included. Conventionally, since the power storage device is controlled by using the SOC including this storage error, the storage capacity corresponding to the storage error in the power storage device cannot be used up.

The SOC accumulation error generated during charging / discharging can be reset by using the voltage between terminals of the power storage device acquired while the charging / discharging of the power storage device is stopped. However, for example, during long-term use of the power storage device, since the voltage between terminals during charging / discharging stop cannot be acquired, the accumulation error cannot be reset for a long period of time, and an excessive increase in the accumulation error cannot be suppressed. There is a demand for a technique capable of suppressing an excessive increase in accumulation error even during charging / discharging of a power storage device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device capable of suppressing an excessive increase in accumulation error even during charging / discharging of a power storage device.

The first means for solving the above-mentioned problems is a control device that controls charging / discharging of the power storage device, that is, a state calculation unit that calculates an SOC indicating the storage state of the power storage device, and charging / discharging of the power storage device. It is provided with an error calculation unit that calculates the accumulation error of the SOC so as to increase with the elapsed time in the medium, and an error reset unit that resets the accumulation error when the accumulation error is larger than a predetermined error threshold. ..

Since the SOC accumulation error during charging / discharging increases with the elapsed time during charging / discharging of the power storage device, the SOC accumulation error becomes large when the elapsed time from the initial stage is long. According to the above configuration, the accumulation error is reset when the accumulation error is larger than the error threshold. As a result, it is possible to suppress an excessive increase in the accumulation error during charging / discharging of the power storage device, and it is possible to prevent a problem in using up the power storage device due to this.

In the second means, the voltage acquisition unit that acquires the voltage between the terminals during charging / discharging of the power storage device and the current that determines that the current during charging / discharging of the power storage device is smaller than a predetermined current threshold value. When the error reset unit is provided with a determination unit, and the error reset unit determines that the accumulation error is larger than the error threshold value and the current during charging / discharging of the power storage device is smaller than the current threshold value. In addition, the accumulation error is reset based on the voltage between terminals acquired by the voltage acquisition unit.

According to the above configuration, when the accumulation error is larger than the error threshold value and the current during charging / discharging is smaller than the current threshold value, the SOC accumulation error is reset based on the voltage between terminals during charging / discharging. To do. That is, if the current during charging / discharging is smaller than the current threshold value, it is determined that the voltage between terminals during charging / discharging is equivalent to the voltage between terminals during charging / discharging, and the voltage between terminals during charging / discharging. Reset the accumulation error based on. As a result, the accumulation error can be reset even during charging / discharging of the power storage device, and it is possible to suppress an excessive increase in the accumulation error.

The third means includes a current acquisition unit that acquires the current during charging / discharging of the power storage device at a predetermined cycle, and the error reset unit is the current acquisition unit when the accumulation error is larger than the error threshold. The accumulated error is reset to a reference error set based on the current acquired by, and the error calculation unit sets the accumulated error so as to increase from the reference error with the elapsed time after the reset of the accumulated error. calculate.

According to the above configuration, the reference error is set based on the current during charging / discharging. Therefore, even after the reset, the current during charging / discharging and the SOC accumulation error can be correlated. Further, depending on the current during charging / discharging, the reference error can be calculated to be small, which is advantageous in using up the power storage device.

The fourth means includes a temperature acquisition unit that acquires the temperature of the power storage device, and the error calculation unit sets the reference error according to the temperature of the power storage device.

According to the above configuration, the reference error is set according to the temperature of the power storage device. Therefore, depending on the temperature of the power storage device, the reference error can be set small, which is advantageous in using up the power storage device.

Schematic diagram of the vehicle system. The flowchart which shows the processing procedure of the control process of 1st Embodiment. The flowchart which shows the processing procedure of ΔSOC calculation processing. The flowchart which shows the processing procedure of ΔSOC reset processing. The figure which shows the relationship between an input / output current and an error amount. The figure which shows the relationship between the input / output current and a reference error. The figure which shows the relationship between an open circuit voltage and a correction coefficient. A time chart showing the transition of ΔSOC during discharge of a high-voltage battery. The figure which shows the relationship between ΔSOC and a power margin. A time chart showing changes in input / output current and closed circuit voltage CCV during the reset period. A time chart showing the transition of maximum power during discharge of a high-voltage battery. The figure which shows the correspondence information of SOC and the maximum power. The figure which shows the relationship between the input / output current, the upper limit voltage and the lower limit voltage. The flowchart which shows the processing procedure of the control process of 2nd Embodiment.

(First Embodiment)
Hereinafter, embodiments will be described with reference to the drawings. This embodiment is applied to an electric vehicle having a motor 13 as a traveling power source, and first, an outline of a vehicle system will be described with reference to FIG.

In FIG. 1, the vehicle includes a high-voltage battery 11, an inverter 12 that converts DC power of the high-voltage battery 11 into AC power, and a motor 13 as a traveling drive source driven by AC power output from the inverter 12. It has. When the vehicle is running, electric power is supplied from the high-voltage battery 11 to the motor 13 via the inverter 12 in response to the accelerator operation by the driver, and the running power is given to the vehicle by the power running drive of the motor 13 accompanying the electric power supply. To. The motor 13 is a rotary electric machine (motor generator) having a power generation function in addition to a power running function. For example, when the vehicle is decelerated, the generated power generated by the regenerative power generation is supplied to the high voltage battery 11 via the inverter 12. In this case, the motor 13 functions as a generator, and the high-voltage battery 11 is charged by the generated power. In this embodiment, the high-voltage battery 11 corresponds to a "power storage device".

The electric power of the high-voltage battery 11 is supplied to the high-voltage auxiliary machine 14 in addition to the motor 13. The high-voltage auxiliary machine 14 is, for example, an electric compressor of an air conditioner for air-conditioning the interior of a vehicle, and is driven by power supplied from the high-voltage battery 11. The high voltage battery 11 is provided with a temperature sensor 15 that detects the battery temperature TM. The high voltage battery 11 is, for example, a lithium ion storage battery, and the voltage between terminals thereof is, for example, about 200 to 300 V.

A low-voltage battery 17 and a low-voltage auxiliary machine 18 are connected to the high-voltage battery 11 via a DCDC converter 16 as a power converter. The DCDC converter 16 performs power conversion in both directions between the high voltage system and the low voltage system. The low voltage battery 17 is, for example, a lead storage battery rated at 12 V. The low-voltage auxiliary machine 18 is, for example, an electric power station, a battery fan, or the like, and in addition to being able to be driven by the electric power from the high-voltage battery 11 supplied via the DCDC converter 16, the electric power is supplied from the low-voltage battery 17. Can be driven by. The DCDC converter 16 steps down the high voltage of the high-voltage battery 11 to the voltage level of the low-voltage battery 17 or the power supply voltage level of the low-voltage auxiliary machine 18, so as to the low-voltage battery 17 and the low-voltage auxiliary machine 18. Supply power.

Further, this system includes an ECU 20 mainly composed of a microcomputer having a CPU and various memories. In addition to the temperature sensor 15 described above, the ECU 20 includes a voltage sensor 21 that detects the voltage between terminals of the high voltage battery 11, a current sensor 22 that detects the input / output current IB of the high voltage battery 11, and an accelerator operation amount AC of the driver. The accelerator sensor 23 for detecting the vehicle speed MV, the vehicle speed sensor 24 for detecting the vehicle speed MV, and the like are connected. Further, an IG switch 25, which is a vehicle start switch, is connected to the ECU 20, and the on / off state of the IG switch 25 is monitored. The ECU 20 controls charging / discharging of the high-voltage battery 11 based on the voltage between terminals of the high-voltage battery 11 and the input / output current IB and the like.

In this case, the ECU 20 calculates an SOC (State Of Charge) indicating the state of charge of the high-voltage battery 11 during charging / discharging of the high-voltage battery 11, and the calculated SOC enables input / output from the high-voltage battery 11. Maximum power WB is set. In this embodiment, the ECU 20 corresponds to a “control device”. Further, when the calculated SOC reaches the upper limit threshold value ST1 or the lower limit threshold value ST2 (see FIG. 12), the charging / discharging of the high voltage battery 11 is stopped. By controlling the charging and discharging of the high-voltage battery 11 based on the SOC, it is possible to prevent the high-voltage battery 11 from being in an overcharged state or an overdischarged state.

However, since the SOC calculated during charging / discharging is calculated using, for example, the time-integrated value of the input / output current IB acquired during charging / discharging, this SOC includes the input / output current IB in the current sensor 22. Detection error ΔSOC, which is an accumulation error according to the integration of GI, is included. Therefore, if the charging / discharging of the high-voltage battery 11 is stopped when the SOC reaches the upper limit threshold value ST1 or the lower limit threshold value ST2, the storage capacity for this ΔSOC cannot be used up. Here, the usage is to increase the storage capacity of the high-voltage battery 11 up to the upper limit threshold value ST1 at the time of charging, and to decrease the storage capacity of the high-voltage battery 11 up to the lower limit threshold value ST2 at the time of discharge.

The ΔSOC generated during charging / discharging can be reset by using the inter-terminal voltage of the high-voltage battery 11 acquired during the charging / discharging stop of the high-voltage battery 11. However, for example, during long-term use of the high-voltage battery 11, since the voltage between the terminals of the high-voltage battery 11 cannot be acquired during charging / discharging stoppage, ΔSOC cannot be reset for a long period of time, and an excessive increase in ΔSOC is suppressed. Can not.

In the present embodiment, in order to suppress an excessive increase in ΔSOC, ΔSOC during charging / discharging is calculated to increase with the elapsed time during charging / discharging of the high-voltage battery 11. In this case, when ΔSOC is larger than the error threshold value ΔST, ΔSOC is reset. As a result, it is possible to suppress an excessive increase in ΔSOC during charging / discharging of the high-voltage battery 11, and it is possible to prevent a problem in using up the high-voltage battery 11 due to this.

FIG. 2 is a flowchart showing a processing procedure of a control process for controlling charging / discharging of the high-voltage battery 11, and this process is repeatedly executed by the ECU 20 at a predetermined cycle when the IG switch 25 is turned on. To.

When the control process is started, first, in step S10, it is determined whether the high voltage battery 11 is being charged or discharged. Immediately after the IG switch 25 is switched to the ON state, since the high-voltage battery 11 has not yet started charging / discharging, a negative determination is made in step S10. In this case, in step S12, the voltage sensor 21 is used to acquire the open circuit voltage OCV, which is the voltage between the terminals of the high voltage battery 11 while the high voltage battery 11 is being charged / discharged. In the following step S14, the SOC is calculated based on the open circuit voltage OCV, and the control process is terminated. Correspondence information in which the open circuit voltage OCV and SOC are associated in advance is stored in the ECU 20, and the SOC is calculated based on the open circuit voltage OCV acquired in step S12 using this correspondence information.

On the other hand, if a predetermined period has elapsed since the IG switch 25 was switched to the ON state, the high-voltage battery 11 has started charging / discharging, and a positive determination is made in step S10. In this case, in step S16, the voltage sensor 21 is used to acquire the closed circuit voltage CCV, which is the voltage between the terminals of the high voltage battery 11 during charging / discharging of the high voltage battery 11. In the following step S18, the input / output current IB is acquired by using the current sensor 22, and the battery temperature TM is acquired by using the temperature sensor 15. That is, during charging / discharging of the high-voltage battery 11, the input / output current IB during charging / discharging of the high-voltage battery 11 is acquired at a predetermined cycle. In the present embodiment, the process of step S16 corresponds to the "voltage acquisition unit", and the process of step S18 corresponds to the "current acquisition unit and temperature acquisition unit".

In the following step S20, the SOC is calculated based on the time integral value of the input / output current IB. In the calculation of SOC based on the time integral value of the input / output current IB, the SOC corresponding to the time integral value of the input / output current IB acquired in a predetermined cycle is compared with the initial value of SOC calculated based on the open circuit voltage OCV. The SOC is calculated by adding the increase / decrease of. Assuming that the initial value of SOC calculated based on the open circuit voltage OCV is SOC (ini) and the full charge capacity of the high voltage battery 11 is CB, the SOC calculated based on the time integrated value of the input / output current IB is ( It is expressed as in equation 1). In this embodiment, the process of step S20 corresponds to the "state calculation unit".

SOC = SOC (ini) + ΣIB · dt / CB ... (Equation 1)
In the following step S22, the ΔSOC calculation process is performed. In this embodiment, the process of step S22 corresponds to the “error calculation unit”.

FIG. 3 shows a flowchart of the ΔSOC calculation process. In the ΔSOC calculation process, the ΔSOC of the SOC is calculated so as to increase with the elapsed time TP (see FIG. 8) during charging / discharging of the high-voltage battery 11.

When the ΔSOC calculation process is started, first, in step S70, the initial value ΔSOC (ini) of ΔSOC is calculated. The initial value ΔSOC (ini) is, for example, an error amount GS at the reset timing when ΔSOC is reset. In this embodiment, the initial value ΔSOC (ini) corresponds to the “initial SOC error”.

In the following step S71, the SOC error amount GS is calculated according to the input / output current IB and the battery temperature TM acquired in step S18. FIG. 5 is a diagram showing the relationship between the input / output current IB and the error amount GS. As shown in FIG. 5, the smaller the input / output current IB, the larger the error amount GS is calculated. The error amount GS is expressed as shown in (Equation 2), where J is the negative proportional coefficient and SGZ is the error amount when the input / output current IB is zero.

GS = J × IB + SGZ ... (Equation 2)
Further, since the input / output current IB fluctuates depending on the battery temperature TM, the error amount GS also fluctuates depending on the battery temperature TM. Correspondence information in which the input / output current IB, the battery temperature TM, and the error amount GS are associated in advance is stored in the ECU 20, and the error amount GS is calculated using this correspondence information.

In addition, based on the calculated error amount GS, the time increase rate θ (see FIG. 8) in which ΔSOC increases with the elapsed time TP is determined. The time increase rate θ is expressed as shown in (Equation 3), where TS is a predetermined cycle that is the acquisition cycle of the input / output current IB.

θ = GS / TS ... (Equation 3)
In the following step S72, the error amount GS from the initial stage is integrated. In the following step S74, the integrated value of the error amount GS calculated in step S72 and the initial error amount GSF calculated in step S70 are added to calculate ΔSOC, and the ΔSOC calculation process is completed. Using the initial value ΔSOC (ini), ΔSOC is expressed as (Equation 4).

ΔSOC = ΔSOC (ini) + ΣGS · dt ... (Equation 4)
Note that ΣGS · dt in (Equation 4) is a time integral value of the error amount GS, and can be expressed as Σ (J × IB + SGZ) · dt using (Equation 2). Of these, IB · dt indicates the time integral value of the input / output current IB, that is, the fluctuation amount of SOC in a predetermined period TS.

When the ΔSOC calculation process is completed, the process returns to FIG. 2, and the ΔSOC reset process is performed in step S24.

FIG. 4 shows a flowchart of the ΔSOC reset process. In the ΔSOC reset process, when a predetermined reset condition is satisfied, ΔSOC is reset during charging / discharging of the high-voltage battery 11.

When the ΔSOC reset process is started, first, in step S80, it is determined whether the ΔSOC calculated in step S72 is larger than the predetermined error threshold value ΔST (see FIG. 8). Here, the error threshold value ΔST is an accumulation error that hinders the use-up of the high-voltage battery 11, and is preset for each battery temperature TM. If a negative determination is made in step S80, the ΔSOC reset process is terminated without resetting the ΔSOC.

On the other hand, if an affirmative determination is made in step S80, that is, when ΔSOC is larger than the error threshold value ΔST, it is determined in step S82 whether ΔSOC is larger than the predetermined reference error ΔSK (see FIG. 8). Here, the reference error ΔSK is a reset error that occurs when ΔSOC is reset during charging / discharging of the high voltage battery 11, and is preset to a value larger than zero. The reference error ΔSK is set based on the input / output current IB and the battery temperature TM acquired in step S18.

FIG. 6 is a diagram showing the relationship between the input / output current IB and the reference error ΔSK. As shown in FIG. 6, the smaller the input / output current IB, the larger the reference error ΔSK is set. Further, since the input / output current IB fluctuates depending on the battery temperature TM, the reference error ΔSK also fluctuates depending on the battery temperature TM. Correspondence information in which the input / output current IB, the battery temperature TM, and the reference error ΔSK are associated in advance is stored in the ECU 20, and the reference error ΔSK is set using this correspondence information.

If a negative determination is made in step S82, the ΔSOC increases due to the reset, so the ΔSOC reset process ends without resetting the ΔSOC.

On the other hand, if an affirmative determination is made in step S82, it is determined in step S84 whether the vehicle is stopped. Here, when the vehicle is stopped, the vehicle speed MV is substantially zero, that is, the vehicle speed MV is smaller than the predetermined speed near zero. Specifically, the input / output current IB is equal to or greater than the predetermined current threshold IT. Is also small. For example, when the input / output current IB acquired in step S18 is smaller than the predetermined current threshold IT for the determination period YA, it is determined that the vehicle is stopped (see FIG. 10). ). Further, for example, when the fluctuation amount ΔV of the closed circuit voltage CCV acquired in step S16 is smaller than the predetermined fluctuation threshold value ΔVT for the determination period YA, it is determined that the vehicle is stopped. (See FIG. 10). Here, the current threshold IT is a current at which the motor 13 can be driven only by supplying electric power from the high voltage battery 11. Further, the fluctuation threshold value ΔVT is the minimum fluctuation amount of the closed circuit voltage CCV generated by driving the motor 13. In this embodiment, the process of step S84 corresponds to the "current determination unit".

If a negative determination is made in step S84, the ΔSOC reset process is terminated without resetting the ΔSOC.

On the other hand, if an affirmative determination is made in step S84, that is, if it is determined that the vehicle is stopped, it is determined in step S86 whether ΔSOC has been reset during the stopped operation. If an affirmative determination is made in step S86, it is determined in step S88 whether the determination period YA has elapsed since the previous ΔSOC was reset. If a negative determination is made in step S88, it is determined in step S90 that the vehicle is restarting. Here, the resumption of running of the vehicle means that the vehicle speed MV becomes larger than the predetermined speed near zero after it is determined that the running of the vehicle is stopped. Specifically, the input / output current IB is higher than the current threshold IT. Is also to grow. For example, when the accelerator operation amount AC by the driver becomes larger than the predetermined first accelerator threshold value AT1 (see FIG. 10), it is determined that the driving of the vehicle is restarted.

In the present embodiment, the first accelerator threshold value AT1 and the second accelerator threshold value AT2 are defined in determining the restart of traveling of the vehicle based on the accelerator operation amount AC, of which the second accelerator threshold value AT2 is the high voltage battery 11. It is the amount of accelerator operation that produces the minimum electric power that the vehicle can travel by supplying electric power from. The first accelerator threshold AT1 is set to an accelerator operation amount smaller than the second accelerator threshold AT2, and by using the first accelerator threshold AT1, it is determined that the vehicle is restarted before the vehicle actually resumes running. it can.

If a negative determination is made in step S90, the ΔSOC is not so large, so the ΔSOC reset process is terminated without resetting the ΔSOC.

On the other hand, if a negative determination is made in step S86, an affirmative determination is made in step S88, or an affirmative determination is made in step S90, ΔSOC is reset based on the closed circuit voltage CCV acquired in step S16. Specifically, in step S92, the SOC is calculated based on the closed circuit voltage CCV acquired in step S16, and the SOC is updated. In the following step S94, ΔSOC is reset to the reference error ΔSK. That is, ΔSOC is reset by updating the SOC in step S92. Therefore, after resetting ΔSOC, ΔSOC is calculated so as to increase from the reference error ΔSK with the elapsed time TP. In the following step S96, the elapsed time TP is reset to zero, and the ΔSOC reset process is completed. In this embodiment, the processes of steps S80 and 94 correspond to the "error reset unit".

When the ΔSOC reset process is completed, the process returns to FIG. 2, and in step S26, it is determined whether the high voltage battery 11 is being charged. For example, the current sensor 22 detects the input / output current IB flowing toward the high-voltage battery 11 as a positive value and the input / output current IB flowing out of the high-voltage battery 11 as a negative value, and the input / input acquired in step S18. Whether the high-voltage battery 11 is being charged can be determined based on whether the output current IB is larger than zero.

If an affirmative determination is made in step S26, the SOC calculated in step S20 or S92 plus the ΔSOC calculated in step S72 is calculated as the SOC in step S28. The SOC calculated in step S28 is the largest SOC in the SOC error range set based on ΔSOC, that is, the SOC error range having twice the width of ΔSOC centered on the SOC. In the following step S30, it is determined whether the SOC calculated in step S28 is smaller than the upper limit threshold value ST1.

If an affirmative determination is made in step S30, that is, if the SOC has not reached the upper limit threshold value ST1, in step S32, the maximum power WB is set based on the SOC calculated in step S28. That is, the maximum power WB is set based on the added value of the SOC calculated in step S20 or S92 and the ΔSOC calculated in step S72. Correspondence information (see FIG. 12) in which the SOC and the maximum power WB are associated in advance is stored in the ECU 20, and the maximum power WB is calculated based on the SOC calculated in step S28 using this correspondence information. Set. Correspondence information is set for the SOC in the range from the upper limit threshold value ST1 to the lower limit threshold value ST2, and is specified for each battery temperature TM. In the following step S34, the charge / discharge of the high voltage battery 11 is controlled by using the maximum power WB set in step S32, and the control process is terminated.

On the other hand, if a negative determination is made in step S30, that is, when the SOC reaches the upper limit threshold value ST1, the maximum power WB is set to the reference input power WK1 (see FIG. 12A) in step S36. In the following step S38, charging of the high voltage battery 11 is continued using the reference input power WK1 set in step S36.

The charge control in step S38 is performed in a high storage state in which the SOC is larger than the upper limit threshold value ST1. In this charge control, the charge stop is controlled by using the closed circuit voltage CCV. In the present embodiment, in controlling the charging stop using the closed circuit voltage CCV, the high voltage side limiting range XH (see FIG. 7A) for stopping the charging of the high voltage battery 11 is predetermined. When the closed circuit voltage CCV belongs to the high voltage side limiting range XH, that is, when the closed circuit voltage CCV reaches the upper limit voltage VT1 which is the lower limit of the high voltage side limiting range XH, the high voltage battery 11 is overcharged. In order to suppress this, charging of the high voltage battery 11 is stopped.

However, since the closed circuit voltage CCV fluctuates depending on the input / output current IB, if the high voltage side limiting range XH is constant regardless of the input / output current IB, the high voltage battery 11 becomes overcharged depending on the input / output current IB. I can't control that. The closed circuit voltage CCV is expressed as shown in (Equation 5), where RB is the internal resistance of the high voltage battery 11.

CCV = OCV + IB x RB ... (Equation 5)
Therefore, in the present embodiment, in step S40, the high voltage side limiting range XH is variably set based on the input / output current IB acquired in step S18. Specifically, the closed circuit voltage CCV and the high-voltage side limiting range XH are set to fluctuate in conjunction with each other based on the input / output current IB. As a result, it is possible to prevent the high voltage battery 11 from being overcharged regardless of the input / output current IB and the battery temperature TM.

In the following step S42, it is determined whether the closed circuit voltage CCV is larger than the upper limit voltage VT1. If a negative determination is made in step S42, the control process ends. On the other hand, if an affirmative determination is made in step S42, the reference input power WK1 set in step S36 is limited in step S44, and the control process ends. In step S44, for example, as shown in FIG. 7A, a correction coefficient that becomes smaller as the closed circuit voltage CCV becomes larger than the upper limit voltage VT1 is set in advance, and this correction coefficient is integrated into the reference input power WK1. The reference input power WK1 is limited. Therefore, the reference input power WK1 gradually decreases as the closed circuit voltage CCV rises, and charging is stopped when the reference input power WK1 becomes zero.

On the other hand, if a negative determination is made in step S26, in step S46, the SOC calculated in step S20 or S92 minus the ΔSOC calculated in step S72 is calculated as the SOC. The SOC calculated in step S46 is the smallest SOC in the SOC error range set based on ΔSOC. In the following step S48, it is determined whether the SOC calculated in step S46 is larger than the lower limit threshold value ST2.

If an affirmative determination is made in step S48, that is, if the SOC has not reached the lower limit threshold value ST2, the process proceeds to step S32. In this case, in step S32, the maximum power WB is set based on the SOC calculated in step S46. On the other hand, if a negative determination is made in step S48, that is, when the SOC reaches the lower limit threshold value ST2, the maximum power WB is set to a constant reference output power WK2 (see FIG. 12B) in step S50. In the subsequent step S52, the high voltage battery 11 is continuously discharged using the reference output power WK2 set in step S50.

The discharge control in step S50 is performed in a low storage state where the SOC is smaller than the lower limit threshold value ST2. In this discharge control, the discharge stop is controlled by using the closed circuit voltage CCV. In the present embodiment, in controlling the discharge stop using the closed circuit voltage CCV, the low voltage side limit range XL (see FIG. 7B) for stopping the discharge of the high voltage battery 11 is predetermined. When the closed circuit voltage CCV belongs to the low voltage side limit range XL, that is, when the closed circuit voltage CCV reaches the lower limit voltage VT2 which is the upper limit of the low voltage side limit range XL, the high voltage battery 11 is in an overdischarged state. The discharge of the high voltage battery 11 is stopped in order to suppress this.

In the present embodiment, in step S54, the low voltage side limit range XL is variably set based on the input / output current IB acquired in step S18. Specifically, the closed circuit voltage CCV and the low voltage side limiting range XL are set to fluctuate in conjunction with each other based on the input / output current IB. As a result, it is possible to prevent the high voltage battery 11 from being over-discharged regardless of the input / output current IB and the battery temperature TM.

In the following step S56, it is determined whether the closed circuit voltage CCV is smaller than the lower limit voltage VT2. If a negative determination is made in step S56, the control process ends. On the other hand, if an affirmative determination is made in step S56, the reference output power WK2 set in step S50 is limited in step S58, and the control process ends. In step S58, for example, as shown in FIG. 7B, a correction coefficient that becomes smaller as the closed circuit voltage CCV becomes smaller than the lower limit voltage VT2 is set in advance, and this correction coefficient is integrated into the reference input power WK1. Limit the reference output power WK2. Therefore, the reference output power WK2 gradually decreases as the closed circuit voltage CCV decreases, and the discharge is stopped when the reference output power WK2 becomes zero.

Subsequently, FIG. 8 shows an example of the ΔSOC calculation process. FIG. 8 shows the transition of ΔSOC during discharging of the high voltage battery 11. In FIG. 8, (A) shows the transition of SOC, (B) shows the transition of ΔSOC, and (C) shows the transition of the reset flag FR. Here, the reset flag FR is a flag indicating the determination result in step S80 of the ΔSOC calculation process, and is turned on when a positive determination is made in step S80 and turned off when a negative determination is made in step S80.

As shown in FIG. 8, the IG switch 25 is switched to the ON state at time t1, the motor 13 is driven by the power supply from the high voltage battery 11, and the vehicle starts running. At this time t1, SOC is calculated based on the open circuit voltage OCV, and ΔSOC is reset to zero.

When the vehicle starts running, the power supply from the high-voltage battery 11 to the motor 13 reduces the SOC. While the high voltage battery 11 is being discharged, the SOC is calculated based on the time integral value of the input / output current IB. When calculating the time integration value of the input / output current IB, the detection error GI of the current sensor 22 that detects the input / output current IB is integrated, so that the integration of the detection error GI causes ΔSOC.

In this embodiment, ΔSOC is calculated to increase with the elapsed time TP from time t1. Specifically, it is calculated so as to increase by the time increase rate θ with respect to the elapsed time TP from the time t1. This time increase rate θ is a positive value and fluctuates depending on the input / output current IB and the battery temperature TM (see time t7 and time t8). Since ΔSOC increases with the elapsed time TP, ΔSOC at time t2 is smaller than ΔSOC at time t3, which is later than time t2.

FIG. 9 is a diagram showing the relationship between ΔSOC and the power margin ΔWB of the maximum power WB. Here, the power margin ΔWB is a setting error of the maximum power WB, and is generated by setting the maximum power WB based on the SOC including ΔSOC. As shown in FIG. 9, the power margin ΔWB increases as ΔSOC increases, and when the power margin ΔWB increases, the maximum power WB cannot be set appropriately, and it is high depending on the set maximum power WB. It is not possible to use up the storage capacity of the voltage battery 11 for ΔSOC, and it is not possible to prevent the high voltage battery 11 from being over-discharged.

In the present embodiment, since ΔSOC increases with the elapsed time TP, there is a timing when ΔSOC is small, for example, at time t2. When ΔSOC is small, the power margin ΔWB is set small. Therefore, by using the timing at which the ΔSOC is small, it is possible to achieve both the exhaustion of the high-voltage battery 11 and the suppression of the over-discharged state.

When ΔSOC reaches the error threshold ΔST at the subsequent time t4, the reset flag FR is switched on. When the vehicle is stopped at time t5 with the reset flag FR turned on, ΔSOC is reset during the reset period YR from the time t5 to the time t6 when the vehicle is stopped. As a result, it is possible to suppress an excessive increase in ΔSOC, and for example, it is possible to suppress an increase in the power margin ΔWB accompanying an increase in ΔSOC, which hinders the use of the high-voltage battery 11.

When the ΔSOC is reset while the high voltage battery 11 is being discharged, the ΔSOC is reset to the reference error ΔSK. The reference error ΔSK is set based on the input / output current IB and the battery temperature TM. Therefore, depending on the input / output current IB and the battery temperature TM, the reference error ΔSK can be set small, which is advantageous in using up the high voltage battery 11.

In the reset period YR from time t5 to time t6, a reference error ΔSK is set at time t5 based on the input / output current IB at this time t5, and ΔSOC is reset to this reference error ΔSK. With the reset of ΔSOC, the reset flag FR is switched off at time t5, and the elapsed time TP is reset to zero. Then, when the vehicle resumes running at time t6, the time counting of the elapsed time TP is restarted. Therefore, it can be said that the elapsed time TP indicates the elapsed time from the reset timing at which ΔSOC was reset immediately before.

After that, the same control as above is repeated. Specifically, when ΔSOC reaches the error threshold ΔST at time t9, the reset flag FR is switched on. When the vehicle is stopped at time t10 with the reset flag FR turned on, ΔSOC is reset during the reset period YR from the time t10 to the time t11 when the vehicle is stopped.

Subsequently, FIG. 10 shows an example of the ΔSOC reset process. FIG. 10 shows the transition of the input / output current IB and the closed circuit voltage CCV in the reset period YR, and specifically shows the transition of these values in the reset period YR from the time t5 to the time t6 in FIG. In FIG. 10, (A) shows the transition of the vehicle speed MV, (B) shows the transition of the accelerator operation amount AC, (C) shows the transition of the input / output current IB, and (D) shows the transition of the closed circuit. The transition of the voltage CCV is shown, and (E) shows the transition of the fluctuation amount ΔV of the closed circuit voltage CCV.

As shown in FIG. 10, when the accelerator operation amount AC by the driver is set to zero and the vehicle speed MV becomes zero at time t5, the power supply from the high voltage battery 11 to the motor 13 decreases, and the input / output current decreases. IB decreases. Along with this, the closed circuit voltage CCV gradually rises so as to gradually approach the open circuit voltage OCV.

The fluctuation amount ΔV of the input / output current IB and the closed circuit voltage CCV due to the increase of the closed circuit voltage CCV decreases with the passage of time from the time t5, and the input / output current IB decreases below the current threshold IT at the time t21. The fluctuation amount ΔV is lower than the fluctuation threshold ΔVT at time t22, which is later than time t21. Of the time t21 and the time t22, the input / output current IB continues to be lower than the current threshold IT and the fluctuation amount ΔV is lower than the fluctuation threshold ΔVT from the later time t22 to the determination period YA. If the low state continues, it is determined that the vehicle is stopped at the time t23 when the determination period YA elapses from the time t22.

When it is determined that the vehicle is stopped at time t23, ΔSOC is first reset at this time t23. Specifically, the SOC is calculated and updated based on the closed circuit voltage CCV that has risen until it approaches the open circuit voltage OCV, and the ΔSOC is reset to the reference error ΔSK accordingly. By resetting ΔSOC based on the closed circuit voltage CCV while the vehicle is stopped, the ΔSOC can be reset even during charging / discharging of the high-voltage battery 11.

While the vehicle is stopped, the high-voltage battery 11 continues to supply electric power to the motor 13 in order to prepare for the subsequent resumption of the vehicle running. Therefore, the input / output current IB is flowing even when the vehicle is stopped, and ΔSOC increases. Therefore, while the vehicle is stopped, the ΔSOC is reset for each determination period YA. For example, the ΔSOC is reset at the time t24 when the determination period YA elapses from the time t23.

Further, while the vehicle is stopped, only YB, which is shorter than the determination period YA, has elapsed since the previous ΔSOC was reset, and even if the determination period YA has not elapsed, the vehicle is restarted. If determined, ΔSOC is reset before the vehicle is actually restarted.

Specifically, when the driver's accelerator operation is started at time t25 and the accelerator operation amount AC exceeds the first accelerator threshold value AT1 at time t26 thereafter, it is determined that the vehicle is restarted. When the accelerator operation amount AC exceeds the second accelerator threshold value AT2 at the subsequent time t6, the running of the vehicle is restarted by the power supply from the high voltage battery 11. As a result, the vehicle speed MV increases, the input / output current IB increases, and the closed circuit voltage CCV decreases apart from the open circuit voltage OCV. By determining the resumption of running of the vehicle using the first accelerator threshold value AT1, it is possible to reset the increase in ΔSOC while the running of the vehicle is stopped before the running of the vehicle is actually restarted and the ΔSOC starts to increase. As a result, it is possible to prevent the ΔSOC from being excessively increased after the vehicle is restarted.

Subsequently, FIG. 11 shows an example of control processing. FIG. 11 shows the transition of the maximum power WB during discharging of the high voltage battery 11. In FIG. 11, (A) shows the transition of SOC, (B) shows the transition of the maximum power WB, and (C) shows the transition of the closed circuit voltage CCV. In the range shown in FIG. 11, since ΔSOC does not become larger than the error threshold value ΔST, it is assumed that the ΔSOC reset process is not performed.

As shown in FIG. 11, while the high-voltage battery 11 is being discharged, the SOC is reduced by the power supply from the high-voltage battery 11 to the motor 13. Along with this decrease in SOC, the closed circuit voltage CCV decreases and the set value of the maximum power WB fluctuates. The maximum power WB is set based on the SOC. As a result, deterioration of the high-voltage battery 11 due to excess power of the high-voltage battery 11 can be suppressed, and the high-voltage battery 11 can be protected.

Specifically, the maximum power WB is set by using the correspondence information between the SOC and the maximum power WB. This correspondence information is preset in consideration of the power excess of the high voltage battery 11. FIG. 12 is a diagram showing correspondence information between SOC and maximum power WB. In FIG. 12, (A) shows correspondence information at the time of charging, and (B) shows correspondence information at the time of discharging. As shown by the solid line in FIG. 12B, the correspondence information at the time of discharge is set so that the larger the SOC, the larger the maximum power WB, and the higher the battery temperature TM, the larger the maximum power WB. Set.

During the discharge of the high-voltage battery 11, the SOC including ΔSOC, specifically, the SOC obtained by subtracting ΔSOC from the SOC in order to suppress the deterioration of the high-voltage battery 11 due to the power excess of the high-voltage battery 11 (SOC-ΔSOC). Is calculated as SOC, and the maximum power WB is set based on this SOC. Hereinafter, the value obtained by subtracting ΔSOC from SOC is referred to as SOL. As shown in FIG. 11, the SOL reaches the lower limit threshold value ST2 before the SOC due to the power supply from the high voltage battery 11 to the motor 13. When the SOL reaches the lower limit threshold value ST2, it is conceivable to stop the discharge of the high voltage battery 11 in order to prevent the high voltage battery 11 from being over-discharged.

However, when the SOL reaches the lower limit threshold value ST2, the SOC is a value obtained by adding ΔSOC to the lower limit threshold value ST2. Explaining using the correspondence information, as shown by the broken line in FIG. 12B, the correspondence information corresponding to the SOL is shifted by ΔSOC to the side where the SOL increases with respect to the correspondence information corresponding to the SOC shown by the solid line. are doing. Therefore, if the discharge of the high-voltage battery 11 is stopped when the SOL reaches the lower limit threshold value ST2, the storage capacity of the high-voltage battery 11 for ΔSOC cannot be used up.

In the present embodiment, as shown by the broken line in FIG. 12B, when the SOL reaches the lower limit threshold value ST2, the maximum power WB is set to the reference output power WK2, and the SOC is high until the lower limit threshold value ST2 is reached. Continue discharging the voltage battery 11. Therefore, even when the maximum power WB is set based on the SOL, the storage capacity for ΔSOC can be used up. Here, the reference output power WK2 is the maximum power WB associated with the lower limit threshold value ST2 in the corresponding information, and is a constant value regardless of the SOC. By setting the reference output power WK2 based on the corresponding information, it is possible to suppress the deterioration of the high voltage battery 11 due to the power excess of the high voltage battery 11 even during the continuous discharge in which the maximum power WB is set to the reference output power WK2. .. The reference output power WK2 is set to a power that allows the vehicle to travel by the motor 13.

Specifically, as shown in FIG. 11, when the SOL reaches the lower limit threshold value ST2 at time t32, the maximum power WB is set to the reference output power WK2, and the high voltage battery 11 continues to be discharged. Due to this discharge, the SOC and the closed circuit voltage CCV decrease. This discharge is performed until the closed circuit voltage CCV reaches the lower limit voltage VT2, and when the closed circuit voltage CCV reaches the lower limit voltage VT2 at time t33, that is, when the closed circuit voltage CCV belongs to the low voltage side limit range XL, FIG. The reference output power WK2 is limited by the correction coefficient shown in (B). As a result, at the time t34 when the SOC reaches the lower limit threshold value ST2, the maximum power WB becomes zero and the closed circuit voltage CCV becomes the lower limit voltage VL, so that the discharge is stopped.

In the present embodiment, the lower limit voltage VT2 is set according to the input / output current IB and the battery temperature TM. FIG. 13 is a diagram showing the relationship between the input / output current IB and the upper limit voltage VT1 and the lower limit voltage VT2. In FIG. 13, (A) shows the relationship between the input / output current IB at the time of charging and the upper limit voltage VT1, and (B) shows the relationship between the input / output current IB at the time of discharging and the lower limit voltage VT2. As shown in FIG. 13B, the lower limit voltage VT2 is set to the low voltage side as the input / output current IB is larger during discharge, and the lower limit voltage VT2 is set to the lower voltage side as the battery temperature TM is higher. Is set.

FIG. 13B also shows the relationship between the input / output current IB at the time of discharge and the closed circuit voltage CCV. At the time of discharge, the closed circuit voltage CCV fluctuates to the low pressure side as the input / output current IB increases. In the present embodiment, the lower limit voltage VT2 is changed in conjunction with the input / output current IB characteristic of the closed circuit voltage CCV. As a result, it is possible to determine whether the closed circuit voltage CCV has reached the lower limit voltage VT2 under a certain condition that does not depend on the input / output current IB, and it is possible to suppress the high voltage battery 11 from being over-discharged.

In the above, the transition of the maximum power WB during the discharge of the high voltage battery 11 is shown, but the same applies to the transition of the maximum power WB during the charging of the high voltage battery 11. Specifically, during charging of the high-voltage battery 11, the SOC is increased by supplying power from the motor 13 to the high-voltage battery 11 by regenerative power generation of the motor 13. As the SOC increases, the closed circuit voltage CCV increases and the set value of the maximum power WB fluctuates. Specifically, the maximum power WB is set using the correspondence information between the SOC and the maximum power WB, and as shown by the solid line in FIG. 12 (A), in the correspondence information at the time of charging, the larger the SOC, the maximum. The power WB is set to be large, and the higher the battery temperature TM is, the larger the maximum power WB is set.

During charging of the high-voltage battery 11, in order to suppress deterioration of the high-voltage battery 11 due to excess power of the high-voltage battery 11, SOC including ΔSOC, specifically, SOC obtained by adding ΔSOC to SOC (SOC + ΔSOC) is used as SOC. The maximum power WB is set based on this SOC. Hereinafter, the sum of SOC and ΔSOC is referred to as SOH (see FIG. 11). The SOH reaches the upper limit threshold value ST1 before the SOC by supplying power from the motor 13 to the high voltage battery 11. When the SOH reaches the upper limit threshold value ST1, it is conceivable to stop charging the high voltage battery 11 in order to prevent the high voltage battery 11 from being overcharged.

However, when the SOH reaches the upper limit threshold value ST1, the SOC is a value obtained by subtracting ΔSOC from the upper limit threshold value ST1. Explaining using the correspondence information, as shown by the broken line in FIG. 12A, the correspondence information corresponding to the SOH shifts by ΔSOC to the side where the SOL decreases with respect to the correspondence information corresponding to the SOC shown by the solid line. are doing. Therefore, if the charging of the high-voltage battery 11 is stopped when the SOH reaches the upper limit threshold value ST1, the storage capacity of the high-voltage battery 11 for ΔSOC cannot be used up.

In the present embodiment, as shown by the broken line in FIG. 12A, when the SOH reaches the upper limit threshold value ST1, the maximum power WB is set to the reference input power WK1 and the SOC is high until the upper limit threshold value ST1 is reached. Continue charging the voltage battery 11. Therefore, even when the maximum power WB is set based on the SOH, the storage capacity for ΔSOC can be used up. Here, the reference input power WK1 is the maximum power WB associated with the upper limit threshold value ST1 in the corresponding information, and is a constant value regardless of the SOC. By setting the reference input power WK1 based on the corresponding information, it is possible to suppress the deterioration of the high voltage battery 11 due to the power excess of the high voltage battery 11 even during the continuous discharge in which the maximum power WB is set to the reference input power WK1. ..

Specifically, when the SOH reaches the upper limit threshold value ST1, the maximum power WB is set to the reference input power WK1 and the charging of the high voltage battery 11 is continued. This charging increases the SOC and the closed circuit voltage CCV. This charging is performed until the closed circuit voltage CCV reaches the upper limit voltage VT1, and when the closed circuit voltage CCV reaches the upper limit voltage VT1, that is, when the closed circuit voltage CCV belongs to the high voltage side limiting range XH, FIG. 7 (A) The reference input power WK1 is limited by the correction coefficient shown in. As a result, charging is stopped at the time when the SOC reaches the upper limit threshold value ST1.

In the present embodiment, the upper limit voltage VT1 is set according to the input / output current IB and the battery temperature TM. As shown in FIG. 13 (A), during charging, the larger the input / output current IB, the higher the upper voltage VT1 is set, and the higher the battery temperature TM, the higher the upper voltage VT1 becomes. Is set. FIG. 13A also shows the relationship between the input / output current IB and the closed circuit voltage CCV during charging. At the time of charging, the closed circuit voltage CCV fluctuates toward the high voltage side as the input / output current IB increases. In the present embodiment, the upper limit voltage VT1 is changed in conjunction with the input / output current IB characteristic of the closed circuit voltage CCV. As a result, it is possible to determine whether the closed circuit voltage CCV has reached the upper limit voltage VT1 under certain conditions regardless of the input / output current IB, and it is possible to prevent the high voltage battery 11 from being overcharged.

According to the present embodiment described above, the following effects are obtained.

The ΔSOC during charging / discharging increases with the elapsed time TP during charging / discharging of the high-voltage battery 11. Therefore, when the elapsed time TP from the initial stage is long, ΔSOC becomes large. In this embodiment, ΔSOC is reset when ΔSOC is larger than the error threshold value ΔST. As a result, it is possible to suppress an excessive increase in ΔSOC during charging / discharging of the high-voltage battery 11, and it is possible to prevent a problem in using up the high-voltage battery 11 due to this.

-In the present embodiment, when ΔSOC is larger than the error threshold value ΔST, ΔSOC is reset based on the closed circuit voltage CCV when the vehicle is stopped. That is, when the vehicle is stopped, since the input / output current IB is smaller than the current threshold IT, it is determined that the closed circuit voltage CCV is equivalent to the open circuit voltage OCV, and ΔSOC is calculated based on the closed circuit voltage CCV. Reset. As a result, ΔSOC can be suitably reset even during charging / discharging of the high-voltage battery 11, and it is possible to suppress an excessive increase in ΔSOC.

-When resetting ΔSOC during charging / discharging of the high-voltage battery 11, ΔSOC is reset to the reference error ΔSK. In the present embodiment, this reference error ΔSK is set based on the input / output current IB. Therefore, the input / output current IB and ΔSOC can be correlated even after the reset. Further, when the input / output current IB is large, the reference error ΔSK can be set small, which is advantageous in using up the high voltage battery 11.

Further, in the present embodiment, the reference error ΔSK is set according to the battery temperature TM. Therefore, depending on the battery temperature TM, the reference error ΔSK can be set small, which is advantageous in using up the high voltage battery 11.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIG. 14, focusing on the differences from the first embodiment. In the first embodiment, the deterioration degree DE of the high voltage battery 11 is calculated in the control process, and the high voltage side limit range XH and the low voltage side limit range XL are variably set based on the calculated deterioration degree DE. Different from the form. Here, the degree of deterioration DE indicates the ratio of the current full charge capacity CB to the full charge capacity CB in the initial state of the high voltage battery 11.

FIG. 14 shows a flowchart of the control process of the present embodiment. Note that, in FIG. 14, the same processing as that shown in FIG. 2 above is given the same step number for convenience, and the description thereof will be omitted.

As shown in FIG. 14, in the control process of the present embodiment, when charging of the high voltage battery 11 is continued using the reference input power WK1 set in step S36 in step S38, the input / output current IB is continued in step S39. The degree of deterioration DE is calculated based on the time integral value of. Specifically, the time integral value of the input / output current IB acquired in a predetermined cycle is calculated, and the deterioration degree DE is calculated so that the larger the time integral value is, the larger the time integral value is.

In the following step S40, the high voltage side limiting range XH is variably set based on the deterioration degree DE calculated in step S39. During charging of the high voltage battery 11, the upper limit voltage VT1 is set to be on the low voltage side as the deterioration degree DE is larger.

Further, in step S52, when the discharge of the high voltage battery 11 is continued using the reference output power WK2 set in step S50, the deterioration degree DE is calculated based on the time integral value of the input / output current IB in step S53. ..

In the following step S54, the low voltage side limit range XL is variably set based on the deterioration degree DE calculated in step S53. During discharging of the high voltage battery 11, the lower limit voltage VT2 is set to be on the high voltage side as the deterioration degree DE is larger.

In the present embodiment described above, the high-voltage side limit range XH and the low-voltage side limit range XL are variably set based on the deterioration degree DE of the high-voltage battery 11. The maximum value of the storage capacity of the high-voltage battery 11 fluctuates due to deterioration, and the high-voltage side limit range XH and the low-voltage side limit range XL fluctuate accordingly. Deterioration of the high-voltage battery 11 is considered by calculating the deterioration degree DE during charging / discharging of the high-voltage battery 11 and variably setting the high-voltage side limit range XH and the low-voltage side limit range XL based on the deterioration degree DE. The high voltage battery 11 can be appropriately protected.

(Other embodiments)
In addition, each of the above-described embodiments may be modified as follows.

The high-voltage battery 11 is not limited to the lithium ion storage battery lithium, and may be another secondary battery that can be charged and discharged.

-In the above embodiment, the maximum power WB is set based on the SOC when the SOC has not reached the upper limit threshold value ST1 or the lower limit threshold value ST2, but the present invention is not limited to this. For example, in the above case, the high voltage battery 11 may be charged / discharged by setting the maximum current that can be input / output from the high voltage battery 11 based on the SOC.

-In the above embodiment, an example of calculating the SOC based on the time integral value of the input / output current IB during charging / discharging of the high voltage battery 11 has been shown, but the present invention is not limited to this. For example, the SOC may be calculated based on a battery model composed of one DC resistor and an RC equivalent circuit. The same applies to the calculation of the degree of deterioration DE.

-In the above embodiment, the charging of the high voltage battery 11 is stopped when the closed circuit voltage CCV reaches the upper limit voltage VT1 in the high storage state, but the present invention is not limited to this. For example, in the above case, the maximum power WB of the high-voltage battery 11 may be limited to prevent the high-voltage battery 11 from being overcharged.

Further, an example is shown in which the discharge of the high voltage battery 11 is stopped when the closed circuit voltage CCV reaches the lower limit voltage VT2 in the low storage state, but the present invention is not limited to this. For example, in the above case, the maximum power WB of the high-voltage battery 11 may be limited to prevent the high-voltage battery 11 from being over-discharged.

-In the above embodiment, the example in which the ECU 20 acquires the battery temperature TM by using the temperature sensor 15 is shown, but the present invention is not limited to this. For example, the ECU 20 may acquire the battery temperature TM by estimating the battery temperature TM based on the accelerator operation amount AC of the driver and the vehicle speed MV.

-In the above embodiment, when the ΔSOC is reset, the SOC is updated based on the closed circuit voltage CCV, and the ΔSOC is reset by this update. However, the present invention is not limited to this, and only the ΔSOC may be reset. ..

-For example, if the elapsed time since the last reset of ΔSOC based on the closed circuit voltage CCV is shorter than the reference time, only ΔSOC is reset, and if it is longer, the SOC is updated based on the closed circuit voltage CCV. ΔSOC may be reset.

-In this case, the reference error ΔSK when resetting ΔSOC based on the closed circuit voltage CCV and the reference error ΔSK when resetting only ΔSOC may be set to different values. For example, the reference error ΔSK when resetting only ΔSOC may be calculated to be larger than the reference error ΔSK when resetting ΔSOC based on the closed circuit voltage CCV.

-In the above embodiment, an example of setting the reference error ΔSK based on the input / output current IB acquired in the reset period YR has been shown, but the present invention is not limited to this. For example, the reference error ΔSK may be set based on the average value of the input / output current IB in the period from the previous reset of ΔSOC to the present time. In the period from the previous reset of ΔSOC to the present time, charging and discharging of the high voltage battery 11 may be switched, so set the reference error ΔSK based on the average value of the absolute values of the input / output current IB. Is preferable.

• The controls and techniques described in this disclosure are provided by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. It may be realized. Alternatively, the control device and method thereof described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control device and method thereof described in the present disclosure may be a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer.

ΔST ... Error threshold, 11 ... High voltage battery, 20 ... ECU, IB ... Input / output current, TP ... Elapsed time.

Claims (4)

A control device (20) that controls charging / discharging of the power storage device (11).
A state calculation unit (S20) that calculates an SOC indicating the power storage state of the power storage device, and
An error calculation unit (S22) that calculates the SOC accumulation error (ΔSOC) so as to increase with the elapsed time (TP) during charging / discharging of the power storage device.
A control device including an error reset unit (S80, S94) that resets the accumulation error when the accumulation error is larger than a predetermined error threshold value (ΔST). A voltage acquisition unit (S16) that acquires the voltage between terminals (CCV) during charging / discharging of the power storage device, and
A current determination unit (S90) for determining that the current (IB) during charging / discharging of the power storage device is smaller than a predetermined current threshold value (IT) is provided.
When it is determined that the accumulation error is larger than the error threshold value and the current during charging / discharging of the power storage device is smaller than the current threshold value, the voltage reset unit is used by the voltage acquisition unit. The control device according to claim 1, wherein the accumulation error is reset based on the acquired voltage between terminals. A current acquisition unit (S18) for acquiring the current (IB) during charging / discharging of the power storage device at a predetermined cycle is provided.
When the accumulation error is larger than the error threshold value, the error reset unit resets the accumulation error to a reference error (ΔSK) set based on the current acquired by the current acquisition unit.
The control device according to claim 1 or 2, wherein the error calculation unit calculates the accumulation error so as to increase from the reference error with the elapsed time after the accumulation error is reset. A temperature acquisition unit (S18) for acquiring the temperature of the power storage device is provided.
The control device according to claim 3, wherein the error calculation unit sets the reference error according to the temperature of the power storage device.

Images