WO2013094743A1

WO2013094743A1 - Battery system

Info

Publication number: WO2013094743A1
Application number: PCT/JP2012/083297
Authority: WO
Inventors: 巧大矢
Original assignee: 三菱重工業株式会社
Priority date: 2011-12-22
Filing date: 2012-12-21
Publication date: 2013-06-27
Also published as: JP2013130504A; JP5272069B2

Abstract

A battery system according to the present invention has an acquisition unit for acquiring the current value of the charging and discharging of a secondary battery, a calculation unit for calculating a first state of charge of the secondary battery, an acquisition unit for acquiring the voltage across the terminals of the secondary battery, an estimation unit for estimating a second state of charge of the secondary battery, a determination unit that determines whether the difference between a representative voltage value derived from the acquired voltage value across the terminals and the voltage value across the terminals commensurate with the first state of charge is attributable to the internal resistance value of the secondary battery, and a correction unit for correcting the first state of charge on the basis of the second state of charge when the difference between the representative voltage value and the voltage value across the terminals is not attributable to the internal resistance value.

Description

Battery system

The present invention relates to a battery system, and more particularly to a battery system for obtaining a charging rate of a secondary battery.

2. Description of the Related Art Conventionally, in vehicles such as automobiles, industrial vehicles, and construction machinery, a secondary battery that can be charged and discharged as a drive source for driving a load such as a motor, and a control device that monitors and controls the secondary battery A battery system is used. In the battery system, for example, the control device can calculate the charge rate (SOC: State Of Charge) of the secondary battery, set an allowable current value according to the calculated charge rate, and supply the load to the load. Various controls such as limiting the current value of the secondary battery are performed.

Here, as one of methods for obtaining the charging rate of the secondary battery, a method of calculating based on the integrated value of the charge / discharge current of the secondary battery is generally known. However, in this method, since the charging rate is obtained by integrating the charging / discharging current, an error has occurred due to factors such as battery temperature. As a result, various control results by the control device are adversely affected.

Therefore, in Patent Document 1, as a method of correcting the charging rate based on the integrated value of the charging / discharging current, when the charging / discharging state of the secondary battery is reversed (when the charging state is reversed from the discharging state or from the charging state) When reversing to the discharging state), the voltage between the terminals of the secondary battery (open voltage) is measured, the charging rate based on the voltage between the terminals is estimated, and the charging rate based on the integrated value of the charging / discharging current is corrected. A method is disclosed.

Japanese Patent Laid-Open No. 11-206028

However, in the technique described in Patent Document 1, since the charge rate based on the integrated value of the charge / discharge current is corrected when the charge / discharge state of the secondary battery is reversed, for example, the charge / discharge state is reversed. If the number is small, there is not enough time to correct the charging rate of the secondary battery, and the charging rate with accumulated errors will be used in each control of the control device, which will adversely affect various control results by the control device. Still had problems.

Therefore, in view of the above problems, the present invention provides a simple new battery system capable of appropriately correcting the charging rate of the secondary battery even when the reversal of the charge / discharge state of the secondary battery is small. For the purpose.

The battery system of one aspect of the present invention integrates the current value acquired by the current value acquisition unit that acquires the current value of the charge / discharge current of the secondary battery over time and the current value acquired by the current value acquisition unit. A charging rate calculation unit that calculates a first charging rate of the secondary battery based on an integrated value, a voltage value acquisition unit that acquires a voltage value between terminals of the secondary battery, and the current value acquisition unit includes the current value Is obtained at a predetermined value or less and continuously for a predetermined time, using the inter-terminal voltage value acquired by the voltage value acquisition unit, based on the correlation between the inter-terminal voltage value of the secondary battery and the charging rate. The voltage value when the absolute value of the difference between the charge rate estimation unit for estimating the second charge rate of the secondary battery and the first charge rate and the second charge rate is equal to or greater than a correction target value. Based on the representative voltage value determined from the inter-terminal voltage value acquired by the acquisition unit and the correlation. A determination unit that determines whether or not the difference between the inter-terminal voltage value according to the estimated first charging rate is due to the internal resistance value of the secondary battery, and the determination unit determines the result, Correction for correcting the first charging rate based on the second charging rate when the difference between the representative voltage value and the voltage value between the terminals according to the first charging rate is not caused by the internal resistance value Part.

According to such a battery system, when the current value is equal to or less than a predetermined value and continues for a predetermined time, the first charging rate calculated by integrating the current value of the charge / discharge current of the secondary battery is calculated between the terminals of the secondary battery. By correcting based on the second charging rate estimated by the voltage value, a charging rate with less error can be used in various controls of the control device, and the influence on the control result can be suppressed.

Here, the inter-terminal voltage value acquired for estimating the second charging rate can be the inter-terminal voltage value when the load is being driven, so depending on the current value of the secondary battery required by the load The voltage drop value due to the internal resistance of the secondary battery may be greatly affected. As a result, depending on the timing at which the inter-terminal voltage value is measured, the inter-terminal voltage value varies greatly, and the second charging rate estimated by the inter-terminal voltage value may not be accurate. Nevertheless, if the first charging rate is corrected based on this second charging rate, the second charging rate that deviates from the actual charging rate rather than the first charging rate is used for various controls of the control device. There is also a risk.

However, according to the battery system of one aspect of the present invention, the first charge can be performed at an appropriate second charge rate by considering the accuracy of the second charge rate estimated based on the internal resistance value of the secondary battery. The rate can be corrected, and the charging rate with less error can be reliably used in various controls of the control device.

In the battery system according to one aspect of the present invention, the determination unit has an internal resistance value of the secondary battery when an absolute value of a difference between the first charging rate and the second charging rate is equal to or greater than a correction target value. The difference between the representative voltage value determined from the inter-terminal voltage value acquired by the voltage value acquisition unit and the inter-terminal voltage value according to the first charging rate estimated by the correlation Is determined to be greater than a voltage drop value due to an internal resistance value of the secondary battery, and the correction unit determines the representative voltage value and the first charging rate as a result of the determination by the determination unit. When the absolute value of the difference from the corresponding inter-terminal voltage value is larger than the voltage drop value, the first charging rate may be corrected based on the second charging rate.

In the battery system according to an aspect of the present invention, the determination unit is configured to acquire the current value acquired by the current value acquisition unit for a certain period including a time point when the voltage value acquisition unit acquires a voltage value between terminals of the secondary battery. Whether the current fluctuation of the current value acquired by the current value acquisition unit is within the predetermined range for the certain period of time. When determined, the first charging rate may be corrected based on the second charging rate.

In the battery system of one embodiment of the present invention, the determination unit is configured to determine whether the secondary battery is in a charged state or a discharged state for a certain period including a time point when the voltage value acquiring unit acquires a voltage value between terminals of the secondary battery. It is further determined whether or not it is in one of the states, and the correction unit determines that the determination unit is in one of the charged state or the discharged state of the secondary battery for the certain period of time. The first charging rate may be corrected based on the second charging rate.

The battery system according to an aspect of the present invention further includes a temperature acquisition unit that acquires the temperature of the secondary battery, and the determination unit has an absolute value of a difference between the first charging rate and the second charging rate. When the correction target value is equal to or higher than the correction target value, a minimum allowable temperature is set according to the internal resistance value of the secondary battery, and it is determined whether the temperature acquired by the temperature acquisition unit is equal to or higher than the minimum allowable temperature. The correction unit corrects the first charging rate based on the second charging rate when the temperature acquired by the temperature acquisition unit is equal to or higher than the minimum allowable temperature as a result of the determination by the determination unit. May be.

According to the battery system of the present invention configured as described above, it is possible to appropriately correct the charging rate of the secondary battery even for a load with few drive stops.

The schematic block diagram of the battery system of this embodiment is shown. An explanatory view for explaining an outline of a work vehicle to which a battery system of this embodiment is applied is shown. In the battery system of this embodiment, the schematic functional block of BMU is shown. In the battery system of this embodiment, an example of the table showing the relationship between the voltage value between terminals of a secondary battery, temperature, and a charging rate is shown. In the battery system of the present embodiment, the usage range of the charging rate of the secondary battery, the calculated first charging rate and the estimated second charging rate are exemplarily shown, and the first charging rate ASOC is the actual charging. The time is smaller than the rate TrSOC. In the battery system of the present embodiment, the usage range of the charging rate of the secondary battery, the calculated first charging rate and the estimated second charging rate are exemplarily shown, and the first charging rate ASOC is the actual charging. The time when it is larger than the rate TrSOC is shown. In the battery system of this embodiment, an example of the table showing the relationship between the internal resistance value of a secondary battery, temperature, and a charge rate is shown, and the case of the internal resistance value at the time of discharge is shown. In the battery system of this embodiment, an example of the table showing the relationship between the internal resistance value of a secondary battery, temperature, and a charge rate is shown, and the case of the internal resistance value at the time of charge is shown. In the battery system of this embodiment, an example of transition of the charging / discharging current of a secondary battery is shown. It is a flowchart which shows the operation processing content of the battery system of this embodiment. It is a flowchart which shows the operation processing content of the battery system of this embodiment.

In the battery system of the present embodiment, the first charge rate ASOC, which may include an error calculated by integrating the charge / discharge current of the secondary battery, is calculated as the second charge rate ESOC estimated by the voltage value between the terminals of the secondary battery. One of the features is that the correction is determined in consideration of the influence caused by the internal resistance value of the secondary battery.

Preferred embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the battery system 1 of this embodiment is demonstrated taking the thing mounted in the work vehicle (for example, unmanned work vehicle) 100 as an example. FIG. 1 is a schematic configuration diagram of the battery system 1, and FIG. 2 is a diagram for explaining an outline of the work vehicle 100.

As shown in FIG. 1, the battery system 1 includes a battery device 2, a host control device 3, a power load 4, and a power receiving unit 5. Battery device 2 includes a plurality of secondary batteries 20 (20a to 20h) as a drive source for driving work vehicle 100. The host controller 3 controls the driving of the work vehicle 100 while exchanging information with the battery device 2. The electric power load 4 is a motor for driving the work vehicle 100 or the like. The power receiving unit 5 receives power from an external power source.

Here, first, the work vehicle 100 will be briefly described with reference to FIG. As shown in FIG. 2, the work vehicle 100 is used as a vehicle that circulates around the stations 111 provided in various places on the circuit 110, receives an object at one station 111, and delivers the object at another station 111. The The work vehicle 100 travels using the secondary battery 20, which is a component of the battery system 1, as a drive source, and receives power supplied from a power supply facility 112 provided at a predetermined location of the circuit 111 via the power receiving unit 5. The secondary battery 20 can be charged by receiving power. The power supply facility 112 has, for example, a power supply line (not shown) arranged along the circuit 110, and supplies external power received from a commercial power source to the work vehicle 100 through the power supply line. For example, when the work vehicle 100 travels, the power receiving unit 5 is an electromagnetic coil disposed along the power supply line, and receives power supplied from the power supply line by electromagnetic induction. Such work vehicle 100 can be driven without stopping for 24 hours while repeatedly charging and discharging the secondary battery 20 of the battery system 1.

Hereinafter, the battery device 2 and the host control device 3 which are components of the battery system 1 will be described in detail.

As shown in FIG. 1, the battery device 2 includes an assembled battery 21 including a plurality of secondary batteries 20 (20a to 20h), which are power sources necessary for driving the work vehicle 100, and a battery management device 22. The The battery device 2 can discharge the power charged in the plurality of secondary batteries 20a to 20h to the power load 4, and can also receive the power received from the commercial power source (not shown) via the power receiving unit 5. Thus, the secondary batteries 20a to 20h can be charged. The secondary batteries 20a to 20h may be secondary batteries that can be charged and discharged, and are, for example, lithium ion secondary batteries.

The assembled battery 21 is configured by connecting a first arm and a second arm in parallel. The first arm includes four secondary batteries 20a to 20d connected in series. The second arm includes four secondary batteries 20e to 20h connected in series. In the assembled battery 21 of the present embodiment, a case where eight secondary batteries 20a to 20h are connected in series or in parallel as shown in FIG. 1 will be described as an example. However, the present invention is not limited to this case. Instead, the number of secondary batteries connected in series or in parallel may be changed as appropriate, or a plurality of secondary batteries may be connected only in series or connected only in parallel.

Also, the battery device 2 is provided with temperature sensors TA to TH, voltage sensors VA to VH, a current sensor IA, and a current sensor IB, respectively. The temperature sensors TA to TH measure the respective temperatures (for example, the temperature of the battery container surface) Ta to Th of the secondary batteries 20a to 20h. Voltage sensors VA to VH measure inter-terminal voltages (cell voltages) Va to Vh between the positive terminals and the negative terminals of the secondary batteries 20a to 20h, respectively. The current sensor IA measures the current Ia flowing through the secondary batteries 20a to 20d of the first arm. The current sensor IB measures the current Ib flowing through the secondary arm secondary batteries 20e to 20h.

Battery management device (Battery Management System: BMS) 22 is a device that centrally manages a plurality of secondary batteries 20a to 20h and transmits / receives various signals to / from host control device 3. The battery management device 22 includes CMUs (Cell Monitor Units) 221 </ b> A and 221 </ b> B and BMUs (Battery Management Units) 222.

The CMU 221A is a unit for monitoring each temperature Ta to Td and each terminal voltage Va to Vd of the secondary batteries 20a to 20d of the first arm, and communicates with the temperature sensors TA to TD and the voltage sensors VA to VD. Connected through a line. The CMU 221A receives, for example, measurement information (temperatures Ta to Td, inter-terminal voltages Va to Vd) measured and output by the above-mentioned various sensors as analog signals, and these analog signals are converted into analog-digital converters (Analog Digital Converter). : ADC), the digital signal corresponding to each is converted, and then an identification ID is assigned to each measurement information and output to the BMU 222 in order to identify the secondary batteries 20a to 20d.

The CMU 221B is a unit for monitoring the temperatures Te to Th and the inter-terminal voltages Ve to Vh of the secondary batteries 20e to 20h of the second arm, and communicates with the temperature sensors TE to TH and the voltage sensors VE to VH. Connected through a line. The CMU 221B receives, for example, measurement information (temperatures Te to Th and terminal voltages Ve to Vh) measured and output by the various sensors as analog signals, and these analog signals are received by an analog-to-digital converter (ADC). After conversion into a digital signal corresponding to each, an identification ID is assigned to each measurement information and output to the BMU 222 in order to identify the secondary batteries 20a to 20d.

In the battery system 1 of the present embodiment, the

CMUs

221A and 221B are provided for each arm to which a plurality of secondary batteries 20 are connected in series. However, the present invention is not limited to this case. It is good also as a structure provided with CMU for every two secondary batteries made, and it is good also as a structure provided with CMU for every individual secondary battery, The structure can be changed suitably.

The BMU 222 is connected to the

CMUs

221A and 221B and the host controller 3 via communication lines, and each piece of measurement information (temperatures Ta to Th, terminal voltages Va to Vh) converted from the

CMUs

221A and 221B into digital signals. Receive. The BMU 222 is connected to the current sensors IA and IB via a communication line in order to monitor the current Ia flowing through the first arm and the current Ib flowing through the second arm. For example, the current sensors IA and IB Measurement information (currents Ia and Ib) to be measured and output are received as analog signals, and these analog signals are converted into corresponding digital signals by an analog-digital converter (ADC). The BMU 222 calculates the charging rate based on the measurement information and transmits / receives various signals to / from the host control device 3.

For example, as shown in FIG. 3, the BMU 222 has a current value acquisition unit 23, a charge rate calculation unit 24, a voltage value acquisition unit 25, and a temperature acquisition unit 26 as processing functions for deriving the charge rate of the battery device 2. A charging rate estimation unit 27, a determination unit 28, and a correction unit 29. The current value acquisition unit 23 acquires information on the currents Ia and Ib from the current sensors IA and IB. The charging rate calculation unit 24 calculates the first charging rate ASOC from the information on the currents Ia and Ib acquired by the current value acquisition unit 23. The voltage value acquisition unit 25 acquires information on the inter-terminal voltage values Va to Vh of the secondary batteries 20a to 20h from the

CMUs

221A and 221B. The temperature acquisition unit 26 acquires information on the temperatures Ta to Th of the secondary batteries 20a to 20h from the

CMUs

221A and 221B. The charging rate estimation unit 27 estimates the second charging rate ESOC based on the information on the inter-terminal voltage values Va to Vh and the temperatures Ta to Th acquired by the voltage value acquisition unit 25 and the temperature acquisition unit 26. The determination unit 28 determines whether to correct the first charging rate ASOC based on the second charging rate ESOC. The correcting unit 29 corrects the first charging rate ASOC based on the second charging rate ESOC. The BMU 222 includes a charge rate storage unit 30 and a table storage unit 31. The charging rate storage unit 30 stores the first charging rate ASOC calculated by the charging rate calculation unit 24 and the second charging rate ESOC estimated by the charging rate estimation unit 27 as the charging rate of the assembled battery 21. The table storage unit 31 stores various tables used by the charging rate estimation unit 27 for estimating the second charging rate ESOC. The BMU 222 includes, for example, a processor for performing various computations and controls, a RAM that temporarily stores information (data), functions as a working area at the time of control, a ROM that stores programs, and peripheral circuits. The processing functions of the above units can be realized.

The current value acquisition unit 23 acquires information on the current values Ia and Ib of the charge / discharge currents flowing through the secondary batteries 20a to 20h in the battery device 2 from the current sensors IA and IB over time. The timing for acquiring the current values Ia and Ib can be appropriately set according to factors such as the characteristics of the work vehicle 100 and the driving situation. For example, the timing for acquiring the current values Ia and Ib is set every 100 msec. Set. The current value acquisition unit 23 notifies the charging rate calculation unit 24 of information on the acquired current values Ia and Ib. In addition, when the current value acquisition unit 23 acquires the current values Ia and Ib below a predetermined value and continuously for a predetermined time, the current value acquisition unit 23 notifies the charging rate estimation unit 27 of information to that effect.

Here, when the current value acquisition unit 23 acquires the current values Ia and Ib below the predetermined value and continuously for a predetermined time, the inter-terminal voltage values Va to Vh of the secondary batteries 20a to 20h are the no-load voltage. For example, the predetermined value can be set to 100 A, and the predetermined time can be set to 10 sec. Note that the predetermined value and the predetermined time can be appropriately set according to factors such as the electric power required to drive the work vehicle 100 and the specifications of the secondary battery.

The charging rate calculation unit 24 integrates the current values Ia and Ib acquired by the current value acquisition unit 23, and based on the integrated value, the first of the assembled battery 21 including a plurality of secondary batteries 20a to 20h. The charging rate ASOC is calculated. The first charging rate ASOC can be calculated by setting the charging rate SOC stored in the charging rate storage unit 30 as the initial charging rate and adding (or subtracting) the charging rate variation to the initial charging rate, The charging rate calculation unit 24 overwrites the calculated first charging rate ASOC in the charging rate storage unit 30 as the charging rate SOC. The method itself for calculating the charging rate by integrating the current values of the charge / discharge current can be the same as the conventional calculation method.

The voltage value acquisition unit 25 acquires the inter-terminal voltage values Va to Vh of the secondary batteries 20a to 20h transmitted from the

CMUs

221A and 221B. The voltage value acquisition unit 25 notifies the information on the acquired inter-terminal voltage values Va to Vh to the charging rate estimation unit 27 and the correction unit 29.

Similarly to the voltage value acquisition unit 25, the temperature acquisition unit 26 acquires the temperatures Ta to Th of the secondary batteries 20a to 20h transmitted from the

CMUs

221A and 221B. The temperature acquisition unit 26 notifies the charging rate estimation unit 27 of information on the acquired temperatures Ta to Th.

Note that the timing at which the voltage value acquisition unit 25 acquires the inter-terminal voltage values Va to Vh and the timing at which the temperature acquisition unit 26 acquires the temperatures Ta to Th depend on factors such as characteristics of the work vehicle 100 and driving conditions. For example, the timing for acquiring each voltage value and temperature may be set every 500 msec, or the current value acquisition unit 23 keeps the current values Ia and Ib below a predetermined value and continues for a predetermined time. When acquired, the timing for acquiring each voltage value and temperature may be the time when the voltage value acquisition unit 25 and the temperature acquisition unit 26 receive information from the current value acquisition unit 23, respectively.

When the charge rate estimation unit 27 receives information indicating that the current values Ia and Ib are continuously acquired for a predetermined time or less from the current value acquisition unit 23, the voltage value acquisition unit 25 acquires Using the voltage values Va to Vh and the temperatures Ta to Th acquired by the temperature acquisition unit 26, the correlation between the voltage value between the terminals of the secondary battery, the temperature, and the charging rate stored in the table storage unit 31 in advance is calculated. With reference to the table shown in FIG. 4, the charging rates ESOC [a] to ESOC [h] of the secondary batteries 20a to 20h are estimated. The charging rate estimation unit 27 further estimates a second charging rate ESOC that is a charging rate of the assembled battery 21 from the estimated charging rates ESOC [a] to ESOC [h] of the respective secondary batteries 20a to 20h. If all the secondary batteries 20a to 20h have the same characteristics, the table may be stored in advance in the table storage unit 31. If at least one secondary battery has different characteristics from other secondary batteries, the table may be stored in the table storage unit 31 in advance for the number of the different characteristics.

Here, normally, the charging rate of the secondary battery 20 has a correlation with the terminal voltage (open voltage OCV) of the secondary battery 20 when there is no load (the current value of the secondary battery is approximately 0 A). Therefore, if the open circuit voltage OCV of the secondary battery 20 can be confirmed, the charging rate of the secondary battery 20 can be estimated. Even when the load is not stopped and the current value of the secondary battery 20 is not approximately 0 A as in the work vehicle 100 of the present embodiment, the current value of the secondary battery 20 is less than or equal to a predetermined value and If it is the voltage between the terminals of the secondary battery 20 when it continues for a predetermined time, the charging rate approximated to the actual charging rate can be estimated while maintaining a certain accuracy. In particular, in the battery system 1, the usage range of the charging rate when the secondary battery 20 is repeatedly charged and discharged is a certain range (for example, 60% to 70%), and the charging rate of the secondary battery 20 is When it falls within the allowable use range (for example, 10% to 90%), there is a margin (20%) between the upper limit of the use range (70%) and the upper limit of the use allowable range (90%). Since there is a margin (50%) between the lower limit (60%) of the use range and the lower limit (10%) of the allowable use range, the method of estimating the charging rate while maintaining the above-described certain accuracy is sufficiently useful. The allowable use range is a use range of a desirable charge rate that can efficiently use the secondary battery 20 and extend the life, and when the charge rate is out of this use range, the secondary battery 20 It is the range where charging / discharging of is restricted. Note that the allowable use range can be changed as appropriate according to the type of the secondary battery 20, and the range may be, for example, 0% to 100%.

The method of estimating the second charging rate ESOC in the charging rate estimating unit 27 is, for example, deriving the maximum charging rate SOC [max] and the minimum charging rate SOC [min] from the charging rates ESOC [a] to ESOC [h]. Then, the intermediate value can be calculated using the following formula (1), and the calculated intermediate value can be estimated as the second charging rate ESOC.

In the battery system 1 of the present embodiment, the second charging rate ESOC estimation method using the above formula (1) is merely an example, and other estimation methods may be used. For example, the charging rate ESOC is simply used. An average value of [a] to ESOC [h] may be calculated, and the calculated average value may be estimated as the second charging rate ESOC.

The determination unit 28 is determined from the inter-terminal voltage values Va to Vh acquired by the voltage value acquisition unit 25 when the absolute value of the difference between the first charging rate ASOC and the second charging rate ESOC is equal to or greater than the correction target value XD1. It is determined whether the difference between the representative voltage value Vr and the inter-terminal voltage value V _ASOC corresponding to the first charging rate ASOC estimated from the correlation is due to the internal resistance value of the secondary battery 20. . Specifically, the determination unit 28 calculates the voltage drop value Vdr due to the internal resistance value of the secondary battery 20, and the difference between the representative voltage value Vr and the inter-terminal voltage value V _ASOC is the calculated voltage drop value Vdr. Determine if greater than.

In other words, since the charging rate calculation unit 24 calculates the first charging rate ASOC by integrating the current values Ia and Ib that may include errors, the first charging rate ASOC can be significantly different from the actual charging rate. . Therefore, it is necessary to correct the first charging rate ASOC based on the second charging rate ESOC that approximates the actual charging rate. However, since the inter-terminal voltage value acquired to estimate the second charging rate ESOC can be the inter-terminal voltage value when the load is being driven, depending on the current value of the secondary battery required by the load The voltage drop value due to the internal resistance of the secondary battery may be greatly affected. As a result, depending on the timing at which the inter-terminal voltage value is measured, the second charging rate estimated from the inter-terminal voltage value may not be accurate. Therefore, the determination unit 28 calculates the voltage drop value Vdr due to the internal resistance value of the secondary battery 20 and corrects the first charging rate ASOC based on the appropriate second charging rate ESOC. It is determined whether or not the charging rate is close to the actual charging rate.

The correction target value XD1 is a value that serves as an index when correcting the first charging rate ASOC based on the second charging rate ESOC. For example, the usage range of the charging rate of the secondary battery 20 in the battery system 1 and It can be determined in consideration of the allowable use range. This is because there is a possibility that the first charging rate ASOC may show a value greatly different from the actual charging rate due to an error, and when the value exceeds the allowable use range, the work vehicle 100 restricts charging / discharging of the secondary battery 20. It is because there is a possibility of doing. Here, for example, if the actual charging rate (true value) is expressed as TrSOC, the allowable use range is 10% to 90%, and the use range is 60% to 70%, when ASOC <TrSOC, FIG. As shown, even if the first charging rate ASOC including an error is equal to or lower than the upper limit (70%) of the usage range, the first charging rate TrSOC exceeds the upper limit (90%) of the allowable usage range. If the charging rate ASOC is used for each control, various control results are adversely affected. Therefore, considering that the difference between the upper limit (90%) of the allowable use range and the upper limit (70%) of the use range is 20%, the correction target value XD1 is set to 20%. On the other hand, when ASOC> TrSOC, as shown in FIG. 5B, even if the first charging rate ASOC including the error is equal to or higher than the lower limit (60%) of the usage range, the actual charging rate TrSOC is lower than the lower limit of the allowable usage range (60%). The correction target value XD1 is set to 20% so as not to fall below 10%). Accordingly, the first charging rate ASOC is at least 40%, which is 20% lower than the lower limit (60%) of the use range, and is corrected based on the second charging rate ESOC, so that no particular problem occurs. The correction target value may be set separately for (1) ASOC <TrSOC and (2) ASOC> TrSOC. For example, the allowable use range is 10% to 90%. If the usage range is 60% to 70%, (1) the correction target value XD1 when ASOC <TrSOC is set to 20%, and (2) the correction target value XD2 when ASOC> TrSOC is set to 30%. May be. Further, as described above, the correction target value XD1 does not set a difference (20%) between the upper limit (90%) of the allowable use range and the upper limit (70%) of the use range, but a margin width α (for example, 5%) may be added as appropriate and set to 15%.

In the determination unit 28, the voltage drop value Vdr is calculated by using the representative temperature Tr determined by the temperatures Ta to Th acquired by the temperature acquisition unit 26 and the second charging rate ESOC estimated by the charging rate estimation unit 27. Referring to the table as shown in FIG. 6A and FIG. 6B showing the relationship between the internal resistance value, temperature, and charging rate of the secondary battery stored in the table storage unit 31 in advance, the secondary battery 20 The internal resistance value Rin is estimated, and the estimated internal resistance value Rin is multiplied by the current value Ia or Ib acquired by the current value acquisition unit 23 to calculate the voltage drop value Vdr. FIG. 6A is an example of a table showing the relationship between the internal resistance value, temperature, and charging rate when the secondary battery 20 is discharged, and FIG. 6B shows the internal resistance value, temperature, and charging when the secondary battery 20 is charged. It is an example of the table which shows the relationship with a rate.

Here, the representative temperature Tr is the temperature Ta˜ that is acquired by the temperature acquisition unit 26 in order to estimate the internal resistance value Rin of the secondary battery 20 when the assembled battery 21 includes a plurality of secondary batteries 20a˜20h. The temperature is determined by Th. For example, as described above, when an intermediate value between the maximum charging rate ESOC [max] and the minimum charging rate ESOC [min] is estimated as the second charging rate ESOC, the representative temperature Tr is similarly set between the temperatures Ta to Th. Of these, it can be determined as an intermediate value between the maximum temperature T [max] and the minimum temperature T [min]. Note that the representative temperature Tr can be determined by another method in accordance with the second charging rate ESOC estimation method, and may be determined as an average value of the temperatures Ta to Th, for example. Further, when there is one secondary battery 20 in the battery device 2, the temperature becomes the representative temperature Tr.

The determination unit 28 is determined by the inter-terminal voltage values Va to Vh acquired by the voltage value acquisition unit 25 when the absolute value of the difference between the first charging rate ASOC and the second charging rate ESOC is equal to or greater than the correction target value XD1. Whether or not the absolute value of the difference between the representative voltage value Vr and the inter-terminal voltage value V _ASOC corresponding to the first charging rate ASOC estimated from the table shown in FIG. 4 is at least greater than the voltage drop value Vdr. Whether or not the following formula (2) is satisfied is determined. Β in the following formula (2), for example, β ≧ 1, is a coefficient, and can be set as appropriate in consideration of an increase in internal resistance due to future deterioration of the secondary battery 20.

Here, the representative voltage value Vr is a voltage value acquisition for comparison with the inter-terminal voltage value V _ASOC corresponding to the first charging rate ASOC when the assembled battery 21 includes a plurality of secondary batteries 20a to 20h. This is a voltage value determined by the inter-terminal voltage values Va to Vh acquired by the unit 25. For example, as described above, when the intermediate value between the maximum charging rate ESOC [max] and the minimum charging rate ESOC [min] is estimated as the second charging rate ESOC, the representative voltage value Vr is similarly the inter-terminal voltage value. An intermediate value between the maximum inter-terminal voltage value V [max] and the minimum inter-terminal voltage value V [min] among Va to Vh can be determined as the representative voltage value Vr. The representative voltage value Vr can be determined by other methods according to the estimation method of the second charging rate ESOC and the like, for example, may be determined as an average value of the inter-terminal voltage values Va to Vh. Further, when there is one secondary battery 20 in the battery device 2, the voltage value between the terminals becomes the representative voltage value Vr.

When the determination unit 28 determines that the absolute value of the difference between the representative voltage value Vr and the terminal voltage value V _ASOC is at least greater than the voltage drop value Vdr, the correction unit 29 determines the first charging rate ASOC as the second charging rate. Correct based on ESOC. That is, the correction unit 29 rewrites the first charging rate ASOC stored as the charging rate SOC in the charging rate storage unit 30 with the second charging rate ESOC.

The determination unit 29 also includes the current values Ia and / or Ib acquired by the current value acquisition unit 23 for a certain period including the time when the voltage value acquisition unit 25 acquires the inter-terminal voltage values Va to Vh of the secondary battery 20. It is also possible to determine whether or not the current fluctuation is within the predetermined range _IP , that is, whether or not the following equation (3) is satisfied. When the determination unit 28 determines that the current fluctuation of the current values Ia and / or Ib acquired by the current value acquisition unit 23 is within the predetermined range for the predetermined period, the correction unit 29 determines the first charging rate. The ASOC may be corrected based on the second charging rate ESOC. That is, when the current value before and after the timing of measurement fluctuates beyond a predetermined range I _P, have a significant impact on the second charging rate ESOC, since the second charging rate ESOC may may not be accurately estimated, corrected part 29, if within a certain predetermined range I _P there is a current variation is corrected based on the first charging rate ASOC second charging rate ESOC. In the following formula (3), I (t) is a current value acquired at the time t when the inter-terminal voltage values Va to Vh are acquired, and I (t−1) is immediately before the time t (for example, The current value acquired before 100 msec), and I (t + 1) is the current value acquired immediately after t (for example, after 100 msec) (the same applies to equation (4) described later).

Here, the predetermined range _{I P,} for example, the correction target range XD1, the voltage drop value of the secondary battery 20 Vdr, CMU221A, be determined in consideration of factors such as the synchronization deviation between 221B and BMU222 Can do. For example, when the correction target range XD1 is set to 20%, the charging rate allowable error due to voltage drop is 10%, the charging rate allowable error due to synchronization shift is 5%, and the charging rate allowable error due to current fluctuation The minutes can be 5%. At this time, for example, if the temperature is 5 degrees, referring to the table shown in FIG. A voltage value is obtained, and an internal resistance value corresponding to the inter-terminal voltage value is obtained with reference to the tables shown in FIGS. 6A and 6B. Then, it is possible to determine the current value obtained from the voltage value and the internal resistance between the terminals as the predetermined range I _P of current fluctuation. Incidentally, the method for determining the predetermined range I _P described above is an example, it may be determined a predetermined range I _P suitable current fluctuation by repeating experiments. Also, the determining unit 28 and the correction unit 29, the fixed period, the current variation of the current value the current value acquiring unit 23 acquires is equal to or within a predetermined range I _P, in accordance with the result, the The functional process of correcting the one charging rate ASOC based on the second charging rate ESOC depends on the usage situation in which the power required by the power load (the current value of the secondary battery) varies greatly in the battery system 1. Although particularly useful, it may be omitted.

The determination unit 28 further includes either the charged state or the discharged state of the secondary battery 20 for a certain period including the time when the voltage value acquiring unit 25 acquires the inter-terminal voltage values Va to Vh of the secondary battery 20. It is also possible to determine whether or not the state is satisfied (that is, whether or not the following expression (4) is satisfied). When the determination unit 28 determines that the secondary battery 20 is in a charged state or a discharged state for the certain period, the correcting unit 29 converts the first charging rate ASOC to the second charging rate ESOC. You may correct | amend based on. For example, as shown in FIG. 7, if the current values I (t−1), I (t), and I (t + 1) at the respective time points t−1, t, and t + 1 are all in the discharge state, the correction unit 29 Corrects the first charging rate ASOC based on the second charging rate ESOC.

The processing of the correction unit 29 has the following useful effects. That is, it is possible to avoid the possibility that the accurate voltage drop value Vdr at the time of reversal of the charging / discharging current of the secondary battery 20 due to factors such as a synchronization shift between the

CMUs

221A, 221B and the BMU 222 cannot be calculated. In addition, in the determination part 28 and the correction | amendment part 29, it is determined whether it is in any one state of the charge state or the discharge state of the secondary battery 20 for the said fixed period, According to the result, 1st charge rate The functional process of correcting the ASOC based on the second charging rate ESOC may be omitted.

The host controller 3 controls the power load 4 such as a motor mounted on the work vehicle 100, and receives information on the charge rate SOC of the assembled battery 21 from the charge rate storage unit 30 of the BMU 222 to charge the battery. Various controls such as setting an allowable current value according to the rate and limiting the current value requested by the power load 4 to the battery device 2 are performed.

Hereinafter, with reference to the flowcharts shown in FIGS. 8 and 9, the setting process of the charging rate of the battery system 1 of the present embodiment performed using the BMU 222 will be described. Note that the processes shown in the flowcharts of FIGS. 8 and 9 can be executed in any order or in parallel as long as the process contents do not contradict each other. The battery system 1 is assumed to use the one shown in FIG. 2, and the table storage unit 31 is assumed to store the table shown in FIG. 4 and the tables shown in FIGS. 6A and 6B in advance.

First, the current value acquisition unit 23 acquires information on the current values Ia and Ib of the charge / discharge currents flowing through the secondary batteries 20a to 20h in the battery device 2 from the current sensors IA and IB over time (step S100). The timing for acquiring the information on the current values Ia and Ib is, for example, every fixed time interval (100 msec).

Next, the charging rate calculation unit 24 integrates the current values Ia and Ib acquired by the current value acquisition unit 23, and calculates the first charging rate ASOC of the assembled battery 21 based on the integrated value (step S101). . The first charging rate ASOC can be calculated by adding (or subtracting) the charging rate variation to the initial charging rate, using the value stored as the charging rate SOC in the charging rate storage unit 30 as the initial charging rate. The calculated first charging rate ASOC is overwritten in the charging rate storage unit 30 as the charging rate SOC. Information stored as the charging rate SOC in the charging rate storage unit 30 can be transmitted to and received from the host control device 3. In addition, the initial charging rate can use the charging rate preserve | saved at the charging rate memory | storage part 30, when the battery system 1 was started and complete | finished last time, for example.

Further, the current value acquisition unit 23 determines whether or not the total of the acquired current values Ia and Ib is equal to or greater than a predetermined value (step S102). If the sum of the current values Ia and Ib is not less than or equal to the predetermined value (step S102: No), the process returns to step S100. The predetermined value can be appropriately set in consideration of the capacity of the assembled battery 21 and the output required by the power load 4, but is set to 100A, for example.

On the other hand, when the sum of the current values Ia and Ib is equal to or less than the predetermined value (step S102: Yes), the current value acquisition unit 23 turns on the timer (step S103) and sets the current value at the predetermined time interval. Is acquired again (step S104).

Then, the charging rate calculation unit 24 integrates the current values Ia and Ib acquired by the current value acquisition unit 23 as in the process of step S101, and the first charging rate of the assembled battery 21 based on the integrated value. ASOC is calculated (step S105). The charging rate calculation unit 24 overwrites the charging rate storage unit 30 again with the first charging rate ASOC calculated in this step as the charging rate SOC.

Here, the current value acquisition unit 23 determines again whether or not the current values Ia and Ib acquired in the process of step S104 are equal to or less than the predetermined value (step S106). When it is not less than the predetermined value (step S106: No), the current value acquisition unit 23 resets the timer (step S107) and returns to the process of step S100.

On the other hand, if it is equal to or smaller than the predetermined value (step S106: Yes), the current value acquisition unit 23 refers to the timer and determines whether or not a predetermined time has elapsed (step S108). If it is determined that the predetermined time has not elapsed (step S108: No), the process proceeds to step S104. In addition, although this fixed time can be suitably set in consideration of the capacity of the assembled battery 21, the magnitude of the output power required by the power load 4, etc., for example, it is set to 10 sec.

In the process of step S108, when the current value acquisition unit 23 determines that a certain time has elapsed (step S108: Yes), the voltage value acquisition unit 25 and the temperature acquisition unit 26 are notified of this, and the voltage value acquisition is performed. The unit 25 and the temperature acquisition unit 26 acquire information on the inter-terminal voltage values Va to Vh and the temperatures Ta to Th from the

CMUs

221A and 221B as measurement information (step S109). The voltage value acquisition unit 25 and the temperature acquisition unit 26 are not limited to the case where the notification from the current value acquisition unit 23 is received, and the information on the terminal voltage values Va to Vh and the temperatures Ta to Th are stored in the CMU 221A, You may make it acquire from 221B every predetermined time (for example, every 500 msec).

Next, the charging rate estimation unit 27 estimates the second charging rate ESOC of the assembled battery 21 based on the acquired measurement information (step S110). Specifically, the charging rate estimation unit 27 uses the information on the acquired inter-terminal voltage values Va to Vh and the temperatures Ta to Th, and prepares the voltage value, the temperature, and the charging voltage of the secondary battery prepared in advance. Referring to the table as shown in FIG. 4 showing the correlation with the rate, the respective charging rates ESOC [a] to ESOC [h] of the secondary batteries 20a to 20h are estimated, and the above formula (1 ) To estimate the second charging rate ESOC.

In the process of step S109, the voltage value acquisition unit 25 and the temperature acquisition unit 26 acquire the information on the inter-terminal voltage values Va to Vh and the temperatures Ta to Th from the

CMUs

221A and 221B every predetermined time. In this case, the charging rate estimation unit 27 uses the assembled battery 21 based on the information on the inter-terminal voltage values Va to Vh and the temperatures Ta to Th before the timing at which the current value acquisition unit 23 acquires the current values Ia and Ib. The second charging rate ESOC may be estimated. In other words, the information on the current values Ia and Ib is directly notified to the BMU 222 from the current sensors IA and IB, while the information on the voltage values Va to Vh and the temperatures Ta to Th is detected by the voltage sensors VA to VH and The BMU 222 is notified from the temperature sensors TA to TH via the

CMUs

221A and 221B. Therefore, there is a time lag for the BMU 222 to receive the information on the current values Ia and Ib and the information on the voltage values Va to Vh between the terminals and the temperatures Ta to Th, and the information on the current values Ia and Ib. It is conceivable that the terminal voltage values Va to Vh and the temperatures Ta to Th are not synchronized with each other. Therefore, the voltage value acquisition unit 25 and the temperature acquisition unit 26 consider the amount of synchronization, and the inter-terminal voltage values Va to Vh and the temperatures Ta to Th a predetermined time before acquiring the current values Ia and Ib. Of the differences between the first charge rate ASOC based on the current value and the second charge rate ESOC based on the voltage value between the terminals in the process of step S111 described later, by acquiring each information of

CMU

221A and 221B, It is possible to remove in advance the amount of synchronization deviation.

Next, the determination unit 28 determines the inter-terminal voltage values Va to Vh acquired by the voltage value acquisition unit 25 when the absolute value of the difference between the first charging rate ASOC and the second charging rate ESOC is equal to or greater than the correction target value XD1. The difference between the representative voltage value Vr determined by the value and the inter-terminal voltage value V _ASOC according to the first charging rate ASOC estimated by the table indicating the correlation stored in the table storage unit 31 is the secondary battery. It is determined whether or not it is due to the voltage drop value of the internal resistance value of 20 (step S111).

The determination process in the determination unit 28 will be described in detail with reference to the flowchart shown in FIG.

First, as shown in FIG. 9, the determination unit 28 determines whether or not a value obtained by subtracting the second charging rate ESOC from the first charging rate ASOC is equal to or greater than the correction target value XD1 (step S200).

In the process of step S200, when it is determined that the correction target value is XD1 or more (step S200: Yes), the determination unit 28 calculates a voltage drop value Vdr due to the internal resistance value of the secondary battery 20 (step S201). On the other hand, when it determines with it not being more than correction object value XD1 (step S200: No), it transfers to the process of step S206.

After the process of step S201, the determination unit 29 uses the above equation (1) to calculate the voltage value acquisition unit 25 from the inter-terminal voltage value V _ASOC corresponding to the first charging rate ASOC estimated from the table shown in FIG. It is determined whether or not a value (V _ASOC −Vr) obtained by subtracting the representative voltage value Vr determined from the acquired inter-terminal voltage values Va to Vh is larger than the voltage drop value Vdr (step S202). However, | Vdr | = | I | × Rin.

In the process of step S202, when it is determined that V _ASOC −Vr is greater than the voltage drop value Vdr (step S202: Yes), the determination unit 28 uses the above equation (4) to determine that the voltage value acquisition unit 25 is a secondary It is determined whether or not the secondary battery 20 is in a charged state or a discharged state for a certain period including the time point when the inter-terminal voltage values Va to Vh of the battery 20 are acquired (step S203). On the other hand, when it is determined that V _ASOC −Vr is equal to or lower than the voltage drop value Vdr (step S202: No), the process proceeds to step S100.

In the process of step S203, when it determines with it being in any one state of a charge state or a discharge state (step S203: Yes), the determination part 28 is the voltage value acquisition part 25 using said Formula (3). certain period including the time when acquiring the voltage value Va ~ Vh between the terminals of the rechargeable battery 20, the current value Ia of the current value acquisition unit 23 acquires a current variation of Ib is whether it is within the predetermined range I _P Determination is made (step S204). On the other hand, when it determines with it not being in any one state of a charge state or a discharge state (step S203: No), it transfers to the process of step S100.

In the process of step S204, the current value Ia of the current value acquisition unit 23 acquires, if the current variation of Ib is determined to be within the predetermined range _{I P} (step S204: Yes), the determination unit 28, a first charging rate The ASOC is corrected based on the second charging rate ESOC (step S205). On the other hand, if the current variation Ia of the current value the current value acquiring unit 23 acquires, Ib is determined not to be within the predetermined range _{I P} (step S204: No), the routine to proceed to step S100.

After step S205, the process returns to the flowchart shown in FIG. 8 and proceeds to step S112.

On the other hand, when it is determined in the process of step S200 that the correction target value XD1 is not equal to or greater than the correction target value XD1 (step S200: No), the determination unit 28 subtracts the first charging rate ASOC from the second charging rate ESOC. It is determined whether or not it is greater than or equal to XD1 (step S206).

In the process of step S206, when it is determined that the correction target value is XD1 or more (step S206: Yes), the determination unit 28 calculates a voltage drop value Vdr due to the internal resistance value of the secondary battery 20 (step S207).

After the processing of step S207, the determination unit 28 sets the first charging rate ASOC estimated by the table shown in FIG. 4 from the representative voltage value Vr determined from the inter-terminal voltage values Va to Vh acquired by the voltage value acquisition unit 25. depending inter-terminal voltage value V (ASOC) value obtained by subtracting _{(Vr-V ASOC)} determines whether is greater than the voltage drop value Vdr (step S208).

If it is determined in step S208 that Vr−V _ASOC is greater than the voltage drop value Vdr (step S208: Yes), the process proceeds to step S203. On the other hand, when it is determined that Vr−V _ASOC is equal to or lower than the voltage drop value Vdr (step S208: No), the process proceeds to step S100.

If it is determined in step S206 that the correction target value is not equal to or greater than XD1 (step S206: No), the timer is reset (step S209), and the process proceeds to step S100.

Returning to the flowchart of FIG. 8, after the process of step S <b> 205 in the process of step S <b> 111, the correction unit 29 corrects the first charge rate ASOC based on the second charge rate ESOC. That is, the correction unit 29 rewrites the first charging rate ASOC stored as the charging rate SOC in the charging rate storage unit 30 with the second charging rate ESOC, and sets the second charging rate ESOC to the initial charging rate in step S101.

As described above, the charging rate setting processing operation is executed in the BMS 222 of the battery system 1 of the present embodiment.

According to the battery system 1 of the present embodiment, when the current value is equal to or less than a predetermined value and continues for a predetermined time, the first charge rate calculated by integrating the current value of the charge / discharge current of the secondary battery is determined as the secondary charge rate. By correcting based on the second charging rate estimated by the voltage value between the terminals of the battery, the charging rate with less error can be used in various controls of the control device, and the influence on the control result can be suppressed.

Further, according to the battery system of the present invention, the voltage drop value due to the internal resistance of the secondary battery is calculated, and the accuracy of the estimated second charging rate is taken into consideration by the calculated voltage drop value, so that the appropriate The first charging rate can be corrected with the second charging rate, and a charging rate with less error can be reliably used in various controls of the control device.

<Modification>
The preferred embodiments of the battery system of the present invention have been described above. However, the present invention should not be limited to the above-described embodiments, and does not depart from the spirit and scope expressed in the claims. Various modifications, additions, and omissions can be made by those skilled in the art.

For example, in the battery system 1 of the present embodiment, the determination unit 28 determines whether or not the absolute value of the difference between the first charging rate ASOC and the second charging rate ESOC is equal to or greater than the correction target value XD1. When the absolute value of the difference is equal to or greater than the correction target value XD1, the voltage drop value Vdr due to the internal resistance value of the secondary battery 20 is calculated, but the present invention is not limited to this. For example, when the absolute value of the difference between the first charging rate ASOC and the second charging rate ESOC is equal to or greater than the correction target value XD1, the determination unit 28 sets the minimum allowable temperature according to the internal resistance value of the secondary battery. Then, it is determined whether or not the representative temperature Tr determined from the temperatures Ta to Th acquired by the temperature acquisition unit 26 is equal to or higher than the minimum allowable temperature, and the correction unit 29 determines the representative temperature Tr as a result of the determination by the determination unit 28. May be corrected based on the second charging rate ESOC when the temperature is equal to or higher than the minimum allowable temperature.

That is, since the internal resistance value and the temperature have a correlation as shown in FIGS. 6A and 6B, for example, the usage range of the charging rate is 60% to 70%, which is within the correction target range XD1. Assuming that the internal resistance value is 1.2 mΩ, referring to FIGS. 6A and 6B, if the temperature is 5 degrees or more, the influence of the voltage drop value of the second charging rate ESOC can be considered to be within the allowable range. . Therefore, when the setting unit 28 sets the minimum allowable temperature to 5 degrees and the correction unit 29 determines that the representative temperature Tr is equal to or higher than the minimum allowable temperature, the first charging rate ASOC is changed to the second charging rate ESOC. Correct based on. By doing so, it is not necessary to previously store the tables shown in FIGS. 6A and 6B in a memory such as the table storage unit 31, and the amount of data to be stored can be reduced. The setting of the minimum allowable temperature in the setting unit 28 can be appropriately input and set by the user in consideration of, for example, the usage environment of the battery system.

Moreover, although the case where it applied to a working vehicle was demonstrated as an example as the battery system 1 of the said embodiment, this invention is not limited to this, The electric power charged by the battery apparatus 2 with respect to a load is variously supplied. For example, vehicles such as electric cars and electric buses, systems for moving bodies used in airplanes and ships, or power storage systems for home use, natural energy generation such as windmills and sunlight. It can also be applied to stationary systems such as a grid interconnection smoothing power storage system combined with the above.

Furthermore, in the battery system 1 of the present embodiment, the case where the battery management device 22 acquires all the inter-terminal voltages Va to Vh and the temperatures Ta to Th of the secondary batteries 20a to 20h has been described as an example. The invention is not limited to this. For example, a secondary battery that acquires the voltage and temperature between terminals may be selected for each arm, and the second charging rate ESOC may be estimated from these. In this case, the number of various measurement sensors (voltage sensors, temperature sensors) can be reduced. Cost can also be suppressed.

Furthermore, in the battery system 1 of the present embodiment, the case where the BMS 22 and the host control device 3 are separately provided has been described as an example. However, in this case, each process of the BMS 22 and the host control device 3 is performed by one control device. You may make it perform.

Furthermore, in the battery system 1 of the present embodiment, the charging rate estimation unit 27 uses the inter-terminal voltage values Va to Vh acquired by the voltage value acquisition unit 25 and the temperatures Ta to Th acquired by the temperature acquisition unit 26. The second charging rate ESOC has been estimated, but the present invention is not limited to this. For example, in a situation where the temperature can be controlled so that the temperature is constant in the battery system 1, the voltage value acquisition unit 25. The second charging rate ESOC may be estimated from only the inter-terminal voltage values Va to Vh acquired by the above. In this case, it is only necessary to prepare a table representing the relationship between the voltage value between terminals at a certain constant temperature and the charging rate.

Furthermore, when the voltage drop value Vdr is calculated by the determination unit 28, the representative temperature Tr determined by the temperatures Ta to Th acquired by the temperature acquisition unit 26 and the second charging rate ESOC estimated by the charging rate estimation unit 27 are calculated. However, the present invention is not limited to this, and for example, in a situation where temperature management can be performed so that the temperature is constant in the battery system 1, the charging rate estimation is performed. The voltage drop value Vdr may be calculated only from the second charging rate ESOC estimated by the unit 27. In this case, it is only necessary to prepare a table representing the relationship between the internal resistance value at a certain temperature and the charging rate.

Further, when the determination unit 28 calculates the voltage drop value Vdr, the internal resistance value Rin of the secondary battery 20 is used by using a table that shows the relationship between the internal resistance value and the charging rate of the secondary battery 20 prepared in advance. The voltage drop value Rin is calculated by multiplying the estimated internal resistance value Rin and the current values Ia and Ib acquired by the current value acquisition unit 23, but the present invention is not limited to this. The voltage drop value may be calculated based on the inter-terminal voltage values Va to Vh of the secondary battery 20 and the current values Ia and Ib acquired by the current value acquisition unit 23.

Furthermore, in the present embodiment, the BMU 222 is provided with various parts according to the application, but some of the parts provided in the BMU 222 may be configured together. One part may be further divided into a plurality of parts.

According to the battery system according to the present invention, it is possible to appropriately correct the charging rate of the secondary battery even with respect to a load with few drive stops.

DESCRIPTION OF SYMBOLS 1 ... Battery system 2 ... Battery apparatus 21 ... Battery assembly 22 ... Battery management apparatus (BMS)
221A, 221B ... CMU
222 ... BMU, 23 ... current value acquisition unit 24 ... charge rate calculation unit 25 ... voltage value acquisition unit 26 ... temperature acquisition unit 27 ... charge rate estimation unit 28 ... determination unit 29 ... correction unit 3 ... high-order control device 4 ... power load (load)
20 (20a to 20h) ... secondary battery 100 ... work vehicle 110 ... circuit 111 ... station 112 ... power feeding device

Claims

A current value acquisition unit that acquires the current value of the charge / discharge current of the secondary battery over time;
A charge rate calculation unit that integrates the current value acquired by the current value acquisition unit and calculates a first charge rate of the secondary battery based on the integrated value;
A voltage value acquisition unit for acquiring a voltage value between terminals of the secondary battery;
When the current value acquisition unit acquires the current value below a predetermined value and continuously for a predetermined time, the voltage value between terminals of the secondary battery is obtained using the voltage value between terminals acquired by the voltage value acquisition unit. And a charging rate estimation unit that estimates a second charging rate of the secondary battery based on the correlation between the charging rate and the charging rate;
When the absolute value of the difference between the first charging rate and the second charging rate is equal to or greater than the correction target value, the representative voltage value determined by the voltage value between the terminals acquired by the voltage value acquisition unit and the correlation A determination unit that determines whether or not the difference between the terminal voltage value according to the first charging rate estimated by the relationship is due to the internal resistance value of the secondary battery;
As a result of the determination by the determination unit, when the difference between the representative voltage value and the inter-terminal voltage value according to the first charging rate is not due to the internal resistance value, the first charging rate is set to the first charging rate. A correction unit for correcting based on the two charging rates;
A battery system comprising:
When the absolute value of the difference between the first charging rate and the second charging rate is equal to or greater than a correction target value, the determination unit calculates a voltage drop value due to the internal resistance value of the secondary battery,
The absolute value of the difference between the representative voltage value determined from the inter-terminal voltage value acquired by the voltage value acquisition unit and the inter-terminal voltage value according to the first charging rate estimated by the correlation is the secondary Judge whether it is larger than the voltage drop value due to the internal resistance value of the battery,
When the absolute value of the difference between the representative voltage value and the inter-terminal voltage value corresponding to the first charging rate is larger than the voltage drop value, the correcting unit determines that the first The battery system according to claim 1, wherein the charging rate is corrected based on the second charging rate.
Whether the current value of the current value acquired by the current value acquisition unit is within a predetermined range for a certain period including the time when the voltage value acquisition unit acquires the voltage value between the terminals of the secondary battery. Determine whether or not
When the determination unit determines that the current fluctuation of the current value acquired by the current value acquisition unit is within a predetermined range for the certain period, the correction unit changes the first charging rate to the second charging rate. The battery system according to claim 1, wherein the correction is performed based on the battery system.
Whether the determination unit is in one of a charged state or a discharged state of the secondary battery for a certain period including a time point when the voltage value acquiring unit acquires a voltage value between terminals of the secondary battery. Is further determined,
The correction unit determines that the first charging rate is based on the second charging rate when the determining unit determines that the charging state or the discharging state of the secondary battery is in the certain period. The battery system according to claim 1, wherein correction is performed.
A temperature acquisition unit for acquiring the temperature of the secondary battery;
When the absolute value of the difference between the first charging rate and the second charging rate is equal to or greater than the correction target value, the determination unit sets a minimum allowable temperature according to the internal resistance value of the secondary battery, Determining whether the temperature acquired by the temperature acquisition unit is equal to or higher than the minimum allowable temperature;
The correction unit corrects the first charging rate based on the second charging rate when the temperature acquired by the temperature acquisition unit is equal to or higher than the minimum allowable temperature as a result of the determination by the determination unit. The battery system according to claim 1.