Battery control device

Abstract

This battery control device for calculating at least temperature information T in order to calculate a permitted power output of a battery includes a surface temperature detecting unit for measuring an actual surface temperature Ts of the battery, an internal temperature calculating unit for estimating an estimated internal temperature Ti of the battery instead of the actual measurement, and a temperature selecting unit for selecting and outputting either of the surface temperature Ts and the estimated internal temperature Ti as the temperature information T, wherein the temperature selecting unit determines a magnitude relationship between a true internal temperature Tt, the surface temperature Ts, and the estimated internal temperature Ti for the current battery, on the basis of information obtained by accumulating, for a plurality of time points, a charge / discharge estimated voltage Ve estimated from a charge / discharge actual voltage Vm of the battery, a charge / discharge actual current I of the battery, and state information of the battery, at a certain time point, and in accordance with the result of the determination, utilizes the selected temperature information T for control. In this way, the present invention provides a battery control device that allows the battery to be used safely while simultaneously realizing the performance of the battery.

Description

[Technical Field]

[0001] The present invention relates to a battery control device. [Background technology]

[0002] In a power storage system or battery system that continuously operates a battery, the system is controlled based on the battery temperature. However, since it is not easy to measure the temperature inside a battery, conventional systems measure the temperature of the battery surface with a sensor and estimate the temperature inside the battery based on the measurement result.

[0003] Furthermore, the electrical characteristics of a battery essentially depend on the true internal temperature Tt, but conventional control using the surface temperature Ts, which is a lower value, excessively limits the allowable power. In order to eliminate errors caused by control using the surface temperature Ts, there is a technology that estimates the true internal temperature Tt, which indicates the essential characteristics of the battery, and uses it for battery control.

[0004] Thus, a technique is known in which the true internal temperature Tt is calculated from the current value, the ambient temperature, and the cooling air volume in addition to the surface temperature Ts, in order to limit power more safely than by using the surface temperature Ts (for example, Patent Document 1).

[0005] There is also known a technology that calculates the difference between the actual measured value of the surface temperature Ts obtained from a temperature sensor and the temperature obtained from a temperature model of the battery, corrects this difference to zero, and uses highly accurate temperature information T for battery control (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-222133 [Patent Document 2] Special Publication No. 2014-531711 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the estimated internal temperature Ti obtained by the techniques described in Patent Documents 1 and 2 above has the problem that errors may occur due to accuracy limitations, and if the accuracy of the calculated estimated internal temperature Ti of the battery is low, the battery controlled based on it will be at a disadvantage in terms of unnecessary limitations on its original capacity, reduced lifespan, and reduced safety reliability.

[0008] If the calculated estimated internal temperature Ti is higher than the true value, the allowable power limit value, which changes depending on the temperature, will be set higher than the value that should be set, and the desired power control will not be achieved. Therefore, it is necessary to check whether the calculated estimated internal temperature Ti is correctly calculated.

[0009] Furthermore, it is necessary to determine whether it is more appropriate to use the directly measurable surface temperature Ts or the estimated internal temperature Ti for the state detection calculation, and to switch the temperature information to be used depending on the situation. The present invention has been made in view of the above-mentioned problems, and its purpose is to propose a battery control device that achieves both safe use of the battery and performance. [Means for solving the problem]

[0010] In order to solve the above problem, the present invention provides a battery control device that calculates at least temperature information T in order to calculate the allowable power of a battery, and includes a surface temperature detection unit that actually measures the surface temperature Ts of the battery, an internal temperature calculation unit that estimates the estimated internal temperature Ti of the battery instead of actually measuring it, and a temperature selection unit that selects and outputs either the surface temperature Ts or the estimated internal temperature Ti as temperature information T, and the temperature selection unit determines the magnitude relationship between the true internal temperature Tt, the surface temperature Ts, and the estimated internal temperature Ti for the current battery based on information accumulated over multiple time periods, including the actual battery charge / discharge voltage Vm at a certain time, the actual battery charge / discharge current I, and the estimated charge / discharge voltage Ve estimated from battery state information, and applies the temperature information T selected based on the result of this determination to control. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a battery control device that achieves both safe use of the battery and performance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a functional block diagram for explaining a battery control device according to an embodiment of the present invention (hereinafter also referred to as "the present battery control device"), and covers the power storage system and its peripheral devices that are the object of control. [Figure 2] 2 is a functional block diagram showing the circuit configuration of a cell control unit that constitutes a cell management unit in the power storage system of FIG. 1. FIG. [Figure 3] 3 is a functional block diagram showing a schematic configuration of a temperature information processing unit that constitutes the battery pack control unit shown in FIGS. 1 and 2. FIG. [Figure 4] FIG. 4 is a functional block diagram showing the configuration of the battery pack control unit shown in FIGS. 1 to 3, and also clearly shows a temperature selection unit. [Figure 5] 5 is an example of a battery equivalent circuit for explaining the processing of the CCV calculation unit in FIG. 4. [Figure 6]5 is a graph illustrating the behavior of the estimated charge / discharge voltage (hereinafter also referred to as "estimated voltage") Ve and the actual charge / discharge voltage (hereinafter also referred to as "measured voltage") Vm for each magnitude relationship pattern (hereinafter also referred to as "temperature magnitude relationship pattern" or "temperature pattern") between the estimated internal temperature Ti and the true internal temperature Tt input to the CCV calculation unit of FIG. 4. [Figure 7] 4 is a flowchart illustrating the processing of a pattern determination unit that configures the temperature selection unit of FIG. 3. [Figure 8] 5 is a graph schematically illustrating the processing of the pattern determination unit in FIG. 4. [Figure 9] 5 is a table illustrating data stored in a pattern storage unit that configures the temperature selection unit of FIGS. 1 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0013] The configuration and operation of the battery control device will be described below with reference to the drawings. Note that the same reference numerals represent the same parts in each drawing. The battery control device is suitable for a plug-in hybrid vehicle equipped with a power storage system 100, and this case will be described below. However, the battery control device can also be applied to other hybrid vehicles and electric vehicles in the same way.

[0014] 1 is a functional block diagram for explaining the present battery control device (no reference numerals). The present battery control device encompasses the power storage system 100 and its peripheral devices (reference numerals 200 to 420) that it controls. The power storage system 100 is connected to an inverter 400 via relays 300 and 310, and is connected to a charger 420 via relays 320 and 330.

[0015] The power storage system 100 includes a battery pack 110, a cell management unit 120, a current detection unit 130, a voltage detection unit 140, a battery pack control unit 150, and a storage unit (not shown). This battery pack control unit 150, together with a charger 420 and an inverter 400, exchanges information with a higher-level vehicle control unit 200 and is under overall control. The vehicle control unit 200 is used when this battery control device is applied to an automobile, and other forms are also possible.

[0016] Note that there is no particular substantive distinction between this battery control device and the power storage system 100, and many of the elements of the functional blocks shown in Fig. 1 belong to both. Here, for the sake of convenience of explanation, the battery control device, which is the main controller with a computer at its core, is expressed differently to conceptually distinguish between the battery control device and the power storage system 100, which is made up of the battery cell groups 112a, 112b (or 112 as in Fig. 2 if no distinction is necessary) and their peripheral devices that are the objects of its control.

[0017] The battery pack 110 is configured by electrically connecting in series a plurality of cells 111 that can store and release electrical energy (charge and discharge DC power). The cells 111 that make up the battery pack 110 are grouped into a predetermined number of units for the purpose of managing and controlling their states.

[0018] The grouped cells 111 are electrically connected in series to form cell groups 112a and 112b (112 if no distinction is made). The number of cells 111 constituting the cell groups 112 may be the same in all cell groups 112, or the number of cells 111 may differ for each cell group 112.

[0019] The cell management unit 120 monitors the state of the cells 111 that make up the battery pack 110. The cell management unit 120 includes a cell control unit 121 provided for each cell group 112. In FIG. 1, cell control units 121a and 121b (collectively 121) are provided corresponding to the cell groups 112a and 112b. The cell control unit 121 monitors and controls the state of the cells 111 that make up the cell group 112.

[0020] In this battery control device, for the sake of simplicity, four cells 111 are electrically connected in series to form cell groups 112a and 112b, and the cell groups 112a and 112b are further electrically connected in series to form a battery pack 110 having a total of eight cells 111.

[0021] The cell groups 112a, 112b are collectively referred to as the battery pack 110, but when viewed as a single power source, they are also referred to as the battery 110. The battery pack 110 is made up of a plurality of cells 111. The cell management unit 120 monitors the state of the cells 111. The current detection unit 130 detects the current flowing through the power storage system 100.

[0022] The voltage detection unit 140 detects the total voltage of the battery pack 110. The battery pack control unit 150 has a function of acquiring an index representing the state of the battery pack 110, detecting the state, and performing optimal control according to the state. The various indexes will be described later.

[0023] The battery pack control unit 150 receives the battery voltage and temperature of the battery 111 transmitted by the cell management unit 120, the value of the current flowing through the power storage system 100 transmitted by the current detection unit 130, and the total voltage value of the battery pack 110 transmitted by the voltage detection unit 140. The battery pack control unit 150 detects the state of the battery pack 110 based on the received information. The result of the state detection by the battery pack control unit 150 is transmitted to the cell management unit 120 and the vehicle control unit 200.

[0024] The battery pack control unit 150 and the cell management unit 120 transmit and receive signals via an insulating element 170, typically a photocoupler, and a signal communication means 160. The insulating element 170 is provided because the battery pack control unit 150 and the cell management unit 120 use different operating power sources.

[0025] That is, the cell management unit 120 operates by receiving power from the battery pack 110, whereas the battery pack control unit 150 uses a battery for on-board accessories (for example, a 14V battery, not shown) as a power source.

[0026] The insulating element 170 may be mounted on the circuit board that constitutes the cell management unit 120, or may be mounted on the circuit board that constitutes the battery pack control unit 150. Depending on the system configuration, the insulating element 170 may be omitted.

[0027] A communication means between the assembled battery control unit 150 and the cell control units 121a and 121b constituting the cell management unit 120 will be described. The cell control units 121a and 121b are connected in series in descending order of potential of the cell groups 112a and 112b that they monitor. A signal sent from the assembled battery control unit 150 to the cell management unit 120 is input to the cell control unit 121a via an insulating element 170 and a signal communication means 160.

[0028] The output of the cell control unit 121a is input to the cell control unit 121b via the signal communication means 160, and the output of the lowest-order cell control unit 121b is transmitted to the battery pack control unit 150 via the insulating element 170 and the signal communication means 160. Note that in this battery control device, the insulating element 170 is not used between the cell control unit 121a and the cell control unit 121b, but signals can also be sent and received via the insulating element 170.

[0029] The memory unit stores information such as the internal resistance characteristics of the battery pack 110, the battery cell 111, and the battery group 112, the capacity at full charge, polarization characteristics, deterioration characteristics, individual difference information, and characteristics of the state of charge (SOC) and open circuit voltage (OCV).

[0030] Although the storage unit in the present battery control device has been illustrated as being installed outside the assembled battery control unit 150 or the cell management unit 120, the present invention is not limited to this. The storage unit may be provided in the assembled battery control unit 150 or the cell management unit 120, and the above information may be stored therein.

[0031] Using the information transmitted by the battery pack control unit 150, the vehicle control unit 200 controls the inverter 400 connected to the power storage system 100 via the relays 300 and 310. The vehicle control unit 200 also controls the charger 420 connected to the power storage system 100 via the relays 320 and 330.

[0032] If the power storage system 100 and the battery control device are applied to a system other than a vehicle system, the vehicle control unit 200 will be replaced with an appropriate one, including the name. Here, a description of application examples other than vehicles will be omitted.

[0033] While the vehicle is running, the power storage system 100 is connected to an inverter 400, and drives a motor generator 410 using energy stored in the battery pack 110. When charging, the power storage system 100 is connected to a charger 420, and is charged by power supplied from a household power source or a charging stand (station).

[0034] The charger 420 is used to charge the battery pack 110 using an external commercial power source (external power source) such as a home or a charging station. In this battery control device, the charger 420 is configured to control the charging voltage, charging current, etc. based on commands from the vehicle control unit 200, but it may also control these in a similar manner based on commands from the battery pack control unit 150. In this way, in this battery control device, there is no strict distinction between the functions of the battery pack control unit 150 and the vehicle control unit 200.

[0035] Charger 420 may be installed inside or outside the vehicle depending on its performance, purpose of use, configuration of the vehicle to which it is applied, installation conditions of the external power source, etc. In other words, there are no limitations on the allocation and placement of each functional unit, and the names of the units may be used as long as the functions of each unit can be distinguished.

[0036] When a vehicle system equipped with the power storage system 100 and this battery control device starts and runs, the battery control device controls the power storage system 100 under the management of a vehicle control unit 200 that is higher in the control hierarchy. The power storage system 100 is connected to an inverter 400, and drives a motor generator 410 using energy stored in a battery pack 110, and during regeneration, the battery pack 110 is charged by the power generated by the motor generator 410.

[0037] When a vehicle equipped with the power storage system 100 is connected to a home power source or an external power source such as a charging station, a charger 420 is connected to the power storage system 100 based on information transmitted by the vehicle control unit 200, and the battery pack 110 is charged until it meets a predetermined condition.

[0038] The energy stored in the battery pack 110 through charging is used the next time the vehicle is driven, or is used to operate electrical equipment inside and outside the vehicle. Furthermore, if necessary, it may be released as a backup power source for a home power supply.

[0039] Fig. 2 is a functional block diagram showing the circuit configuration of a cell control unit 121 that constitutes the cell management unit 120 in the power storage system 100 of Fig. 1. The cell control unit 121 includes a voltage detection circuit 122, a control circuit 123, a signal input / output circuit 124, and a temperature detection unit 125.

[0040] The voltage detection circuit 122 measures the voltage across the terminals of each cell 111. The control circuit 123 receives the measurement results from the voltage detection circuit 122 and the temperature detection unit 125, and transmits them to the battery pack control unit 150 via the signal input / output circuit .

[0041] Circuit configurations that are generally implemented in the cell control unit 121 include circuits that equalize the voltage and SOC variations between the cells 111 that occur due to self-discharge, variations in current consumption, etc. These circuits are considered to be well known and are therefore not described here.

[0042] 2 has a function of measuring the temperature of the cell group (battery) 112. The temperature detection unit 125 measures one temperature for the cell group 112 as a whole, and treats this as a temperature representative value for the individual temperatures of the cells 111 that make up the cell group 112.

[0043] The temperature measured by the temperature detection unit 125 is used for various calculations to obtain an index for detecting the state of the cell 111, the cell group 112, or the battery pack 110. In FIG. 2, based on this premise, one temperature detection unit 125 is provided in the cell control unit 121.

[0044] It is also possible to provide a temperature detection unit 125 for each cell 111 to measure the temperature of each cell 111 and perform various calculations based on the individual temperatures of each cell 111, but in this case the number of temperature detection units 125 will increase, making the configuration of the cell control unit 121 more complex.

[0045] 2 shows the temperature detection unit 125 for simplicity. In reality, a temperature sensor (not shown) is installed at the object to be measured. The installed temperature sensor outputs temperature information as a voltage, and the measurement result is transmitted to the signal input / output circuit 124 via the control circuit 123. The signal input / output circuit 124 outputs the measurement result to the outside of the cell control unit 121.

[0046] The function for realizing this series of steps is implemented in the cell control unit 121 as the temperature detection unit 125, and the voltage detection circuit 122 can also be used to measure the temperature information (voltage). In this battery control device, it is assumed that a temperature sensor is installed on the surface of the battery and measures the surface temperature Ts of the battery. In other words, the temperature detection unit 125 functions as a surface temperature detection unit that actually measures the surface temperature Ts of the battery.

[0047] 3 shows the battery pack control unit 150 according to the present invention and its component, the temperature information processing unit 500. The battery pack control unit 150 is a part that determines the state and allowable power of the battery pack based on the current value, voltage value, and temperature of the battery pack while the vehicle is running, and the temperature information processing unit 500 is a component of the battery pack control unit 150.

[0048] The battery pack control unit 150 is composed of a unit that calculates the battery deterioration rate SOH (State of Health), SOC, and OCV, a unit that calculates the allowable power, etc., but in order to briefly explain the contents of the present invention, only the SOC calculation unit 151 and the temperature information processing unit 500, which are related to the present invention, will be described below in this order. The SOC calculation unit 151 calculates the SOC of the single battery 111. Equation (1) is an example of an equation used by the SOC calculation unit 151 to calculate the SOC.

[0049]

number

[0050] SOC(t) is the SOC at time t, SOC0 is the SOC in the initial state before charging or discharging the battery 111, I(t) is the current flowing through the battery 111 at time t, and Qmax is the full charge capacity of the battery 111. SOC0 is estimated based on the terminal voltage measured before the battery 111 is charged or discharged.

[0051] The above-mentioned memory unit stores characteristic data indicating the relationship between the SOC of the battery 111 measured in advance and the electromotive force OCV, and the initial SOC of the battery 111 is estimated as SOC0 based on the battery voltage measured at a timing before charging / discharging when the voltage of the battery 111 can be considered equal to the electromotive force OCV.

[0052] Furthermore, Qmax is determined experimentally by charging and discharging the cells 111, and a value similarly stored in advance in the storage unit is used. The SOC calculation unit 151 may calculate the SOC of each of the multiple cells 111 individually using the method described above, or may calculate a single SOC for the entire battery pack 110. In this case, the initial SOC can be calculated based on the total voltage obtained from the voltage detection unit 140 and the SOC and OCV characteristic data that takes into account the number of cells 111 connected in series.

[0053] Next, the temperature information processing unit 500 will be described. The temperature information processing unit 500 has an internal temperature calculation unit 510 and a temperature selection unit 520. The operation of these units will be described in order. The internal temperature calculation unit 510 receives as input the battery SOC transmitted from the SOC calculation unit 151, the actual charge / discharge current I transmitted from the current detection unit 130, and the battery surface temperature Ts measured by the temperature sensor, and calculates and estimates the internal temperature of the battery, outputting it as an estimated internal temperature Ti.

[0054] There are various methods for calculating and estimating the internal temperature, but in this battery control device, an example using the thermal network method will be described. Equation (2) expresses the estimated internal temperature Ti(t) at time t calculated by the internal temperature calculation unit 510 using a function f.

[0055]

number

[0056] The function f in equation (2) is defined by the thermal network method. The thermal network method is a method for expressing the thermal system being modeled as the transfer of heat between multiple simplified mass points. The amount of heat transfer is determined by the temperature difference and thermal resistance between two points, and the amount of heat transferred or generated is stored as heat used to raise the temperature of mass points throughout the system.

[0057] In equation (2), Δt is the time interval for calculating the internal temperature and is a predetermined value. Ts(t) is the battery surface temperature Ts measured by the temperature sensor. Ti(t-Δt) is the internal temperature calculated one calculation step before, but the first calculation immediately after starting the battery system uses the temperature Ts measured by the temperature sensor. Furthermore, Qgen(t) is the amount of heat generated from time t-Δt to time t and is defined by the following equation (3).

[0058]

number

[0059] Here, R is the internal resistance of the battery. It is generally known that the internal resistance of a battery depends on the SOC and battery temperature. Here, the internal temperature does not necessarily refer to only one point inside the battery, but also includes the temperatures of the calculation targets inside and outside the battery used in function f. For example, in a thermal circuit model, function f includes not only the mass point at the center inside the battery, but also mass points on the surface of the battery and mass points of components outside the battery, and these temperatures can also be calculated using the thermal circuit model.

[0060] The temperature selection unit 520 executes a determination operation, which will be described later, and then selects and outputs one of the two pieces of input temperature information T, the estimated internal temperature Ti and the battery surface temperature Ts. The temperature selection unit 520 receives as input information the actual charge / discharge current I, the battery surface temperature Ts transmitted from the cell management unit 120, the measured voltage Vm, and the SOC output from the above-mentioned SOC calculation unit 151, and outputs it as temperature information T. Note that the measured voltage Vm is mainly a closed circuit voltage (CCV, On-load voltage). Details of this temperature selection unit 520 will be described later.

[0061] 4 is a functional block diagram showing the configuration of the battery pack control unit 150 shown in FIGS. 1 to 3, and also shows the temperature selection unit 520. The temperature selection unit 520 includes a CCV calculation unit 521, a pattern determination unit 522, a pattern storage unit 523, and a temperature output unit 524. The CCV calculation unit 521 calculates an estimated voltage Ve using the actual charge / discharge current I, the estimated internal temperature Ti, the battery's charging rate, and the SOC.

[0062] The pattern determination unit 522 receives the measured voltage Vm, which is the actual measurement value of the battery voltage, the actual charge / discharge current I, and the calculated battery voltage value described above, i.e., the estimated voltage Ve, and determines the temperature pattern by referring to the pattern information stored in the pattern storage unit 523, which will be described later. The determination result is then output to the temperature output unit 524, which will be described later.

[0063] The method of calculating the estimated voltage Ve by the CCV calculation unit 521 will be described later in detail. The pattern determination unit 522 receives as input the measured voltage Vm, which is the actual measurement value of the battery voltage, the actual charge / discharge current I, and the calculated battery voltage value, i.e., the estimated voltage Ve, and references temperature pattern information received from a pattern storage unit 523, which will be described later, to transmit information on the temperature to be selected to the temperature output unit 524.

[0064] Based on a command from the pattern determination unit 522, the temperature output unit 524 selects either the estimated internal temperature Ti or the battery surface temperature Ts and outputs it as temperature information T. First, the operation of the CCV calculation unit 521 will be described. The CCV calculation unit 521 estimates the terminal voltage (CCV) of the cell 111 during charging and discharging based on the concept of the equivalent circuit model of the battery shown in FIG.

[0065] Fig. 5 is an example of a battery equivalent circuit for explaining the processing of the CCV calculation unit 521 in Fig. 4, where OCV represents the electromotive force that changes depending on the SOC, and Ro represents the DC resistance component including the material resistance of the electrodes, etc. Also, the behavior in which the battery voltage transiently fluctuates with a certain time constant due to charging and discharging is represented by a parallel circuit of Rp and C.

[0066] Here, Rp is called the polarization resistance, C is called the polarization capacity, and the transient response time constant of the parallel connection of Rp and C is defined as τ. In this case, if the voltage applied to Ro when the actual charging / discharging current I flows through the battery is Vo, and the polarization voltage applied to the polarization resistance Rp and polarization capacity C is Vp, the terminal voltage of the battery, CCV, is expressed as in equation (4).

[0067]

number

[0068] The polarization voltage Vp is calculated by the formula (5).

[0069]

number

[0070] ts is the operation period, and Vp is calculated every time period Ts. Also, Vp_z in Equation (5) is the polarization voltage calculated in the previous operation period. The CCV calculation unit 521 estimates and calculates the voltage of the single cell 111 based on Equations (4) and (5). However, as described above, OCV is obtained from the characteristic data of SOC and OCV that are pre-held according to the input SOC.

[0071] Also, since the values of the equivalent circuit parameters Ro, Rp, and τ also vary according to the SOC, temperature, and current of the battery, the characteristic data of Ro, Rp, and τ obtained experimentally in advance are stored in the storage unit and used during the calculation of CCV. These characteristic data are referred to particularly for the purpose of improving the relationship between the temperature error and the deterioration of control accuracy.

[0072] Here, it is assumed that the temperature used when the CCV calculation unit 521 estimates the terminal voltage CCV of the single cell 111 is the estimated internal temperature Ti of the battery estimated by the internal temperature calculation unit 510 described above. Consider the magnitude relationship between the estimated internal temperature Ti and the true internal temperature Tt of the single cell 111, and the estimated voltage (charge / discharge estimated voltage) Ve. The true internal temperature Tt here is equivalent to the surface temperature Ts of the battery measured in a state where the temperature from the surface to the center of the battery can be regarded as uniform.

[0073] FIG. 6 is a graph illustrating the behaviors of the estimated voltage Ve calculated and estimated, and the measured voltage (charge / discharge actual voltage) Vm measured, for each pattern of the magnitude relationship (temperature pattern) between the estimated internal temperature Ti and the true internal temperature Tt input to the CCV calculation unit of FIG. 4.

[0074] The internal temperature calculation unit 510 estimates and calculates the internal temperature of the single cell 111, but since there is an error in the calculation, the estimated temperature does not necessarily exactly match the true internal temperature Tt. Therefore, it is expected that the estimated internal temperature Ti and the true internal temperature Tt are in a magnitude relationship of either Ti < Tt shown in FIG. 6(1) or Tt < Ti shown in FIG. 6(2).

[0075] The graph in Fig. 6(1) shows the time variations of voltage, voltage difference, and current when Ti < Tt. The upper graph in Fig. 6(1) shows the measured voltage Vm and the estimated voltage Ve calculated by the CCV calculation unit 521. The solid line represents the measured voltage Vm, and the dashed line represents the estimated voltage Ve. The middle graph shows the difference ΔV (ΔV = Ve - Vm) between the estimated voltage Ve and the measured voltage Vm. The lower graph shows the current flowing through the battery, and the polarity is defined as positive for charging and negative for discharging.

[0076] In the relationship of Ti < Tt shown in Fig. 6(1), that is, when the estimated internal temperature Ti is lower than the true internal temperature Tt, a temperature value lower than the actual value is input to the CCV calculation unit 521 as the estimated internal temperature Ti. Then, when calculating the estimated voltage Ve of the battery, the CCV calculation unit 521 refers to the value of the equivalent circuit parameter used, which is the original value, that is, the value corresponding to the estimated internal temperature Ti lower than the true internal temperature Tt.

[0077] It is known that generally, the lower the temperature of the battery, the higher its internal resistance and the longer its transient response time. Therefore, for Ro, Rp, and τ shown in the equivalent circuit of Fig. 5, values larger than the original values are used in the CCV calculation.

[0078] Therefore, as derived from the relationships in equations (4) and (5), when larger values than the actual values are used as each equivalent circuit parameter, the CCV is calculated to be high during charging, and conversely, the CCV is calculated to be low during discharging. This is as shown in the upper graph of Fig. 6(1).

[0079] Here, focus on the relationship between the voltage difference ΔV shown in the middle graph of Fig. 6(1), the current in the lower graph of the same figure, and the sign (hereinafter referred to as "positive / negative sign") indicating whether each is positive or negative. In this battery control device, the voltage difference ΔV is defined as Ve - Vm. Since ΔV does not take an absolute value, its value can be either positive or negative.

[0080] As shown in FIG. 6(1), during charging, ΔV takes a positive (+) value, and during discharging, ΔV takes a negative (-) value. Therefore, as shown in FIG. 6(1), when the estimated internal temperature Ti is lower than the true internal temperature Tt, the positive / negative sign of the current and the positive / negative sign of the voltage difference ΔV are the same.

[0081] Next, consider the case of Tt < Ti in FIG. 6(2). At this time, contrary to the case of FIG. 6(1) described above, when the CCV calculation unit 521 calculates the battery voltage, each equivalent circuit parameter is used with a value smaller than the actual value. Therefore, the magnitude relationship between the estimated voltage Ve and the measured voltage Vm during charging and discharging is reversed compared to FIG. 6(1).

[0082] Therefore, focusing on the positive / negative signs of the voltage difference ΔV and the current, as shown in FIG. 6(2), during charging, that is, when the current is positive, ΔV is negative, and during discharging, that is, when the current is negative, ΔV is positive.

[0083] That is, as shown in FIG. 6(2), when the estimated internal temperature Ti is higher than the true internal temperature Tt, the positive / negative signs of the current and the voltage difference ΔV are opposite to each other. Based on this concept of the combination of the current, the voltage difference, and their respective positive / negative signs, the operation of the following pattern determination unit 522 will be described.

[0084] FIG. 7 is a flowchart illustrating the processing of the pattern determination unit 522 that constitutes the temperature selection unit 520 in FIG. 3. Each functional unit is formed when the CPU executes a program in a computer provided in this battery control device.

[0085] When starting the processing, the pattern determination unit 522 reads, in step S521, the charge / discharge actual current I flowing for actual charge / discharge, the measured voltage Vm, and the estimated voltage Ve as synchronous data, and obtains the voltage difference ΔV, which is the value obtained by subtracting the measured voltage Vm from the estimated voltage Ve. Next, in step S522, the pattern determination unit 522 branches the determination and processing according to the value of the charge / discharge actual current I. When the absolute value of the current is smaller than a predetermined value Ith, that is, when the determination is NO, it returns to S521.

[0086] On the other hand, if the current is equal to or greater than Ith in step S522, the pattern determination unit 522 proceeds to step S523, where it accumulates a synchronized data set of I and voltage difference ΔV. Next, the pattern determination unit 522 proceeds to step S524, where it checks the number of accumulated data. As will be described later with reference to FIG. 8, if the number of data points N is equal to or greater than a predetermined number Nth in step S524, the pattern determination unit 522 proceeds to S525, and if it is less than Nth, it returns to S521 again.

[0087] Fig. 8 is a graph showing a schematic example of the processing of the pattern determination unit 522 in Fig. 4. As shown in Fig. 8, the charging / discharging actual current I and the voltage difference ΔV are divided into four regions, region α to region δ, according to the signs of the voltage difference ΔV and the charging / discharging actual current I. Region α is the region where the signs of both the voltage difference ΔV and the charging / discharging actual current I are positive. Region β is the region where the charging / discharging actual current I is negative and the voltage difference ΔV is positive.

[0088] In step S525, the pattern determination unit 522 classifies each of the Nth data sets into four areas, area α to area δ in FIG. 8, based on the degree of uneven distribution of the plot positions, based on the combination of the positive and negative signs of the actual charge / discharge current I and the voltage difference ΔV, and counts the number of data sets in each area.

[0089] Also, in FIG. 8, when the absolute value of the current is less than Ith, it is plotted as a white circle and is not counted as a data point. When the total number of black circles whose absolute value of the current is equal to or greater than Ith reaches Nth, the counting ends. In this way, the pattern determination unit 522 ends the counting when the number of black circles reaches Nth. Note that the graph in FIG. 8 is merely for convenience of explanation, and the calculation processing of the computer does not need to be visually recognized by an image display or the like; it is sufficient to execute a program that performs threshold determination in the same manner as in the explanation of FIG. 8.

[0090] 7, in step S526, the pattern determination unit 522 reads the pattern information from the pattern storage unit 523. The information on the temperature pattern stored in the pattern storage unit 523 will be described later with reference to FIG.

[0091] In S525, the pattern determination unit 522 simultaneously selects one maximum value |ΔV|max of the absolute value of the voltage difference ΔV included in each of the Nth data sets. Furthermore, in S525, the pattern determination unit 522 transmits to the pattern storage unit 523 the breakdown of the Nth data sets classified and summarized into regions α to δ in FIG. 8 and information on |ΔV|max.

[0092] In S526, the pattern storage unit 523 determines a magnitude relationship pattern in accordance with the above-mentioned information transmitted from the pattern determination unit 522, and returns the determined temperature pattern to the pattern determination unit 522. With support from the pattern storage unit 523, the pattern determination unit 522 determines magnitude relationship patterns A to C in S525 and S526 in accordance with the above-mentioned information which will be described using FIGS.

[0093] Fig. 9 is a table illustrating data stored in the pattern storage unit 523 constituting the temperature selection unit 520 in Fig. 1 to Fig. 4. As shown in Fig. 9, the pattern storage unit 523 stores determination conditions for determining whether the estimated internal temperature Ti is estimated to be higher or lower than the actual internal temperature Tt, or whether Ti ≈ Tt is an approximate match, with respect to the temperature information T of the battery pack 110.

[0094] For example, when the number of plot points in region β is greater than that in region γ and the number of plot points in region δ is greater than 1, the pattern determination unit 522 determines that the pattern is pattern A. The pattern conditions for making such a determination are stored in the pattern storage unit 523. In step S527, the pattern determination unit 522 performs pattern determination based on the result of checking against the pattern conditions in the pattern storage unit 523.

[0095] In step S527, the pattern determination unit 522 compares and determines which of patterns A to C shown in Fig. 9 the Nth data sets classified and aggregated into areas α to δ in Fig. 8 correspond to. Then, in step S528, the pattern determination unit 522 sends an output request to the temperature output unit 524 in accordance with the pattern determined in the previous step S527, i.e., an output request for each temperature magnitude relationship pattern.

[0096] 9 shows examples of temperature patterns and judgment conditions stored in the pattern storage unit 523. The first pattern A corresponds to the case where |ΔV|max, which is the maximum absolute value of the voltage difference ΔV, is equal to or less than a predetermined value (threshold value) ΔVth.

[0097] The voltage difference ΔV is the voltage difference between the actually measured voltage and the estimated voltage of the battery, and the smaller this value, the closer the internal temperature to the true value is input to the CCV calculation unit 521. In other words, if |ΔV|max is a sufficiently small value, it means that the internal temperature calculation unit 510 can accurately estimate the internal temperature regardless of the breakdown of the Nth data sets into regions α to δ.

[0098] In Fig. 9, pattern B corresponds to the case where |ΔV|max is greater than the predetermined value ΔVth, and the breakdown of the number of data points is such that the number of data points in region β is greater than the number of data points in region γ, and the number of data points in region δ is greater than the number of data points in region α. ​​In this case, since |ΔV|max is greater than the predetermined value ΔVth, it is determined that there is a certain amount of deviation between the estimated internal temperature Ti and the true internal temperature Tt. Furthermore, the number of data points is concentrated in regions β and δ, and when plotted in Fig. 8, it can be seen that they are unevenly distributed downward to the right (not shown).

[0099] This means that the positive / negative signs of the actual charging / discharging current I and the voltage difference ΔV are often reversed. As explained using Figure 6, this is the case when the estimated internal temperature Ti is higher than the true internal temperature Tt. Therefore, the temperature magnitude relationship pattern in pattern B in Figure 9 is surface temperature Ts < true internal temperature Tt < estimated internal temperature Ti.

[0100] In Figure 9, pattern C is the opposite of pattern B, where the number of data points is concentrated in region α and region γ, and the plot points are visually unevenly distributed in an upward sloping pattern to the right, as shown in Figure 8. In other words, since the positive / negative sign of the actual charging / discharging current I and the positive / negative sign of the voltage difference ΔV are often the same, the estimated internal temperature Ti is shifted lower than the true internal temperature Tt, as explained in Figure 6 (1). Therefore, the temperature pattern shown in pattern C in Figure 9 is surface temperature Ts < estimated internal temperature Ti < true internal temperature Tt.

[0101] 7, in step S526, pattern determination unit 522 receives pattern information from pattern storage unit 523. Then, in step S527, it is determined whether the pattern information received in the previous step is the same as the pattern received during the previous processing.

[0102] In step S527, for example, if pattern A was received in the previous processing and the currently received pattern is also pattern A, pattern determination unit 522 proceeds to step S528. On the other hand, if the currently received pattern is other than pattern A, pattern determination unit 522 proceeds to step S529C because it is different from the previous pattern.

[0103] In other words, when the same pattern is received two or more times in succession, it is determined that the magnitude and direction of the difference between the estimated internal temperature Ti and the true internal temperature Tt are stable, and a temperature switching command is sent to the temperature output unit 524, which will be described later. In this battery control device, the condition for proceeding from step S527 to step S528 is that the same pattern is received two or more times in succession, but the number of times may be increased or decreased as appropriate, for example, three or more times in succession, or four or more times in succession.

[0104] In step S528, pattern determination unit 522 determines whether the temperature pattern received from pattern storage unit 523 in this processing is pattern B or something else, and branches the processing. If the received pattern is pattern B, the process proceeds to step S529A, where it transmits a command to temperature output unit 524 to select surface temperature Ts. At this time, if surface temperature Ts has already been selected when temperature output unit 524 receives the command, it continues to select and output surface temperature Ts.

[0105] On the other hand, if the estimated internal temperature Ti has been selected, the temperature output unit 524 switches the selected temperature from the estimated internal temperature Ti to the surface temperature Ts and outputs it in accordance with the command from the pattern determination unit 522. If the currently received pattern is not pattern B in step S528, the pattern determination unit 522 proceeds to step S529B and transmits a command to the temperature output unit 524 to select the estimated internal temperature Ti. The subsequent operations are the same as those in step S529A.

[0106] Furthermore, when the process proceeds from step S527 to step S529C, the pattern determination unit 522 receives a different temperature pattern from the pattern storage unit 523 each time, and the determination is not stable, so it does not issue a temperature selection switch command to the temperature output unit 524. Therefore, in this case, the temperature output unit 524 continues to select the temperature that it had selected up to that point, either the surface temperature Ts or the estimated internal temperature Ti.

[0107] In step S528, if the estimated internal temperature Ti, which is pattern B, is calculated to be higher than the true internal temperature Tt, the pattern determination unit 522 selects the battery surface temperature Ts, which is lower than the internal temperature, and otherwise selects the estimated internal temperature Ti. The aim of this operation is to prioritize safer battery operation. When calculating the allowable power and other calculations related to the input / output performance of the battery, estimating the temperature information T to be higher poses a higher risk in terms of battery management.

[0108] 9, when the temperature magnitude relationship pattern is determined to be pattern B, the estimated internal temperature Ti may be higher than the true internal temperature Tt. Therefore, it is safer to use the surface temperature Ts, which can be considered lower than the true internal temperature Tt, as the temperature information T used for the allowable power calculation, etc.

[0109] Returning to FIG. 4, the temperature output unit 524 selects either the estimated internal temperature Ti or the actually measured surface temperature Ts in response to the output request for each temperature magnitude relationship pattern sent from the pattern determination unit 522 described above, and outputs the temperature information T to the higher-level calculation unit.

[0110] As a selection criterion for the temperature information T, in the case of pattern B where the estimated internal temperature Ti is calculated to be higher than the true internal temperature Tt, a surface temperature Ts lower than the internal temperature Tt is selected, while in the cases of patterns A and C, the estimated internal temperature Ti is selected. This is because estimating a temperature higher than the true internal temperature Tt poses a higher risk in terms of battery management.

[0111] As described above, according to the present battery control device, by selecting the more appropriate temperature for battery control from the estimated internal temperature Ti and the surface temperature Ts as the temperature information T used for various battery controls, it is possible to achieve both safety in battery control and performance of the battery input / output characteristics.

[0112] The battery 110 in the power storage system 100 is not limited to a lithium ion secondary battery, but can be applied to all power storage systems 100 configured with chargeable and dischargeable storage elements such as nickel-metal hydride batteries, lead-acid batteries, electric double layer capacitors, and lithium ion capacitors.

[0113] By applying the present invention, it is possible to suppress deterioration of battery cells and extend their lifespan in a system and method for controlling a battery, thereby contributing to the manufacture, sale, and maintenance of battery control systems and improving the reliability of the energy storage system 100.

[0114] [supplement] Storage batteries are used in a wide range of fields, from mobile devices to ensuring stable power grid connections. In recent years, battery-powered vehicles such as electric vehicles and hybrid vehicles have been attracting attention as a way to combat the depletion of fossil fuels and to reduce exhaust gases, especially CO2 emissions.

[0115] The battery storage system 100 mounted on these vehicles is equipped with a battery control device that detects the battery voltage, temperature, and current, calculates state quantities such as the battery charging rate based on these, and determines the battery current / voltage control values, as shown in Figure 1. This battery control device is suitable for the battery 111 used in hybrid vehicle control systems, etc., the battery storage system 100, and power control systems related to the charging and discharging thereof.

[0116] The battery pack control unit 150 in this battery control device is composed of a calculation unit for SOH (an index showing the deterioration rate, health and deterioration state of the battery, and showing the ratio of the full charge capacity (Ah) at the time of deterioration to the initial full charge capacity (Ah) as a percentage), SOC (remaining battery capacity, "remaining capacity (Ah) / full charge capacity (Ah) × 100"%), OCV (open circuit voltage), allowable power, etc.

[0117] Furthermore, in reality, the true internal temperature Tt cannot be measured in real time, but a hypothetical true internal temperature Tt is used for convenience. First, the equivalent circuit parameters Ro, Rp, and τ of the cell 111 described above are experimentally measured. In this case, the cell 111 to be measured is stored for a sufficiently long time in a thermostatic chamber or the like that can maintain a predetermined temperature, and the cell 111 is charged and discharged in a state in which the temperature can be considered to be the same from the cell surface to its center, to obtain each parameter. These are treated as hypothetical equivalent circuit parameters corresponding to the true internal temperature Tt.

[0118] Many battery control parameters depend on battery temperature, a typical example being direct current resistance (DCR). It is known that DCR increases as battery temperature decreases. In other words, due to the temperature dependency of DCR, for example, allowable power decreases as battery temperature decreases.

[0119] The allowable power is the maximum power that a battery can output, set for the purpose of battery protection, and a decrease in the allowable power at low temperatures poses a problem of reduced battery performance in cold regions. The energy storage system 100 calculates the allowable power using temperature information (battery temperature) T as input. This temperature information T must be accurate.

[0120] If this temperature information T is inaccurate, it becomes difficult to achieve both safe use of the battery 110 and full performance. Specifically, an unnecessarily excessive safety margin may be set for the allowable power, resulting in a problem in which the battery is unable to achieve its full potential based on its inherent performance. Conversely, there may also be problems caused by overly relaxing the limit on the allowable power, which is set to the minimum necessary for battery life or safety reasons.

[0121] As described above, the pattern determination unit 522 determines the temperature pattern by referring to the pattern information stored in the pattern storage unit 523. In this battery control device, the temperature magnitude relationship pattern (temperature pattern) is identified based on the determination conditions shown in Fig. 9, and it is determined which of the first to third magnitude relationship patterns A to C the pattern corresponds to. That is, the determination is made by the determination means shown in Figs. 7 to 9 based on the state and behavior of the battery shown in Fig. 6, but is not limited to this.

[0122] The determination means is a type of pattern recognition. Pattern recognition is a type of natural information processing, and is a process of selecting and extracting objects that have a certain rule or meaning from data containing miscellaneous information such as images and sounds. This process may be performed by artificial intelligence (AI). In contrast, the determination means shown in Figures 7 to 9 can be reliably and easily realized by a program that mainly performs threshold selection and logical judgment, which is simpler than AI.

[0123] The functions of each calculation unit are realized by the CPU of the computer included in the battery control device, which reads out a calculation program from memory and executes it according to the purpose. This computer can be a one-chip microcomputer, but it can also be a personal computer, or it can be part of a computer used for other purposes.

[0124] The present battery control device can be summarized as follows. [1] As shown in Figures 1, 3 and 4, the battery control device inputs at least temperature information (battery temperature) T to calculate the allowable power of the battery. The battery control device has a temperature detection unit 125, an internal temperature calculation unit 510, and a temperature selection unit 520.

[0125] The temperature detection unit 125 actually measures and detects the surface temperature Ts of the battery 110. The internal temperature calculation unit 510 estimates the estimated internal temperature Ti of the battery 110 by calculation instead of actual measurement, and outputs the estimated internal temperature Ti. The temperature selection unit 520 selects either the surface temperature Ts or the estimated internal temperature Ti and applies it to control.

[0126] The temperature selection unit 520 selects either the surface temperature Ts or the estimated internal temperature Ti based on the following information. At the selection stage, the relative magnitudes of the current surface temperature Ts, the estimated internal temperature TiTt, and the estimated internal temperature Ti are determined. The information used for this determination has the following first and second requirements:

[0127] The first requirement is information about the magnitude relationship between the true internal temperature Tt, the surface temperature Ts, and the estimated internal temperature Ti of the battery 110. The second requirement is data that associates, for the battery 110 at a certain time, the measured voltage (actual charging / discharging voltage) Vm, the measured current (actual charging / discharging current) I, and the estimated voltage Ve estimated from the state information of the battery 110, and that is information that accumulates this data for multiple times.

[0128] This information can be linked to information that compiles specifications, experimental values, rules of thumb, etc. for the battery 110, and can be used as a control decision condition in the battery control device. The battery control device calculates the allowable power of the battery 110 based on this information. This allowable power is achieved by a calculation program that balances safe use of the battery 110 with its performance.

[0129] The battery control device configured as described above safely controls the battery 110 in a manner that is appropriate to apply the surface temperature Ts if it determines that it is appropriate to apply the surface temperature Ts based on information accumulated to grasp the state of the battery 110 at a certain time. On the other hand, depending on the state of the battery 110 at a different time, the battery control device controls the battery 110 in a manner that is appropriate to apply the estimated internal temperature Ti, thereby achieving the best performance.

[0130] As described above, based on the accumulated information, the battery control device determines which of the directly measurable surface temperature Ts and the estimated battery estimated internal temperature Ti is more appropriate to use in the state detection operation in terms of control, and switches the temperature information T to be used according to the situation, thereby making it possible to achieve both safe use and performance of the battery 110. In other words, it is possible to improve the reliability of various state operations using the temperature information T of the battery, exhibit the original performance, and safely operate the battery.

[0131] [2] In the battery control device of [1] above, the temperature selection unit 520 shown in FIGS. 3 and 4 includes a pattern holding unit 523, a pattern determination unit 522, and a temperature output unit 524. The pattern holding unit 523 holds any one of the first to third magnitude relationship patterns A to C selected based on the information accumulated for a plurality of time periods.

[0132] The pattern determination unit 522 collates the current magnitude relationship of the battery with the first to third magnitude relationship patterns held by the pattern holding unit 523 and determines which of them it corresponds to. The temperature output unit 524 selects and outputs the temperature information T according to the result of the determination by the pattern determination unit 522.

[0133] Also, the temperature selection unit 520 selects either the surface temperature Ts or the estimated internal temperature Ti for the temperature information T applied to calculate the allowable power of the battery. In order to optimally select, under the condition that the surface temperature Ts < the estimated internal temperature Ti, for the magnitude relationship among the true internal temperature Tt of the battery, the surface temperature Ts, and the estimated internal temperature Ti, as shown in FIG. 9, the first to third magnitude relationship patterns A to C are defined.

[0134] According to FIG. 9, in the first magnitude relationship pattern A, the magnitude relationship among the three temperatures is estimated to be Ti ≒ Tt under the condition that the surface temperature Ts < the estimated internal temperature Ti. In the second magnitude relationship pattern B, the magnitude relationship among the three temperatures is estimated to be Ts < Tt < Ti. In the third magnitude relationship pattern C, the magnitude relationship among the three temperatures is estimated to be Ts < Ti < Tt.

[0135] When the temperature output unit 524 determines that the first magnitude relationship pattern A or the third magnitude relationship pattern C exists, it outputs the estimated internal temperature Ti. When the temperature output unit 524 determines that the second magnitude relationship pattern B exists, it outputs the surface temperature Ts. According to the present battery control device of [2], the battery state and behavior shown in FIG. 6 are used to make a determination by the determination means shown in FIGS. 7 and 9. This determination means can be reliably and easily realized by a program that mainly involves threshold selection and logical determination, which is simpler than AI.

[0136] [3] As shown in Fig. 9, in the present battery control device of [2] above, the first magnitude relationship pattern A stored in the pattern storage unit 523 corresponds to a case where, among the information accumulated over multiple time periods, the maximum absolute value |ΔV|max of the difference between the measured voltage Vm and the estimated voltage Ve is equal to or less than a predetermined value ΔVth. Also, the second magnitude relationship pattern B and the third magnitude relationship pattern C correspond to a case where, among the information accumulated over multiple time periods, the maximum absolute value |ΔV|max of the difference between the measured voltage Vm and the estimated voltage Ve exceeds a predetermined value ΔVth.

[0137] According to the present battery control device of [2], if the pattern determination unit 522 determines that the first magnitude relationship pattern A (plot points are unevenly distributed near the actual charge / discharge current I axis in the graph of FIG. 8) exists, the difference between the measured voltage Vm and the estimated voltage Ve is small, and therefore the accuracy of the battery temperature information T is high, and good battery control is performed based on that, and the battery condition is determined to be good.

[0138] On the other hand, if the second magnitude relationship pattern B or the third magnitude relationship pattern C is met, it is determined that the battery is deteriorating and that control is required that takes into account the reduced accuracy of the temperature information T. In other words, this allows the battery state to be clearly understood.

[0139] The first size relationship pattern A (flat in FIG. 8) stored in the pattern storage unit 523 also serves as a criterion for distinguishing between the second size relationship pattern B (the plot points are unevenly distributed in a downward-sloping direction to the right, the opposite of FIG. 8) and the third size relationship pattern C (the plot points are unevenly distributed in an upward-sloping direction to the right, as in FIG. 8 itself), making the distinction between them easy and clear.

[0140] [4] In the present battery control device described in [3] above, the second magnitude relationship pattern B (which slopes downward to the right, opposite to that in FIG. 8) and the third magnitude relationship pattern C (which slopes upward to the right in FIG. 8 itself) stored in the pattern storage unit 523 are determined based on the magnitude relationship between the estimated voltage Ve and the measured voltage Vm, and the combination of the polarity of the measured current (actual charging / discharging current) I, among the information accumulated over multiple time periods. As shown in FIG. 8, if 37 pieces of data are acquired and plotted, for example, every second, a certain degree of accuracy can be ensured in the determination by the pattern determination unit 522.

[0141] [5] As shown in Figure 6 (2), in the present battery control device of [4] above, the second magnitude relationship pattern B (opposite to Figure 8, downward sloping to the right) is a magnitude relationship pattern that corresponds to the case where the estimated voltage Ve tends to be lower than the measured voltage Vm when the measured current (actual charging / discharging current) I is charging, and the estimated voltage Ve tends to be higher than the measured voltage Vm when the measured current (actual charging / discharging current) I is discharging.

[0142] In the present battery control device of [5] above, the pattern determination unit 522 references the pattern information stored in the pattern storage unit 523 to determine whether the temperature pattern is the upward-sloping pattern shown in Figure 8 or something else. At this time, the determination is made by the determination means shown in Figures 7 to 9 based on the battery state and behavior shown in Figure 6. The determination means uses a program that mainly involves threshold selection and logical determination, which is simpler than AI, to reliably and easily determine that the pattern is pattern B (Figure 9), which is downward-sloping and opposite to Figure 8.

[0143] [6] As shown in Figure 6(1), in the present battery control device of [4] above, the third magnitude relationship pattern C (rising upward to the right in Figure 8 itself) is a magnitude relationship pattern that corresponds to the case where the estimated voltage Ve tends to be higher than the measured voltage Vm when the measured current (actual charging / discharging current) I is charging, and the estimated voltage Ve tends to be lower than the measured voltage Vm when the measured current (actual charging / discharging current) I is discharging.

[0144] The battery control device described above in [5] also uses a program-based judgment means that mainly involves simple threshold selection and logical judgment compared to AI, and can reliably and easily determine that the upward-sloping pattern C (Figure 9) in Figure 8 itself is correct. [Explanation of symbols]

[0145] 100: power storage system, 110: assembled battery (battery), 111: cell, 112a, 112b (112 if no distinction is necessary): cell group, 120: cell management unit, 121a, 121b (collectively 121): cell control unit, 122: voltage detection circuit, 123: control circuit, 124: signal input / output circuit, 125: temperature detection unit, 130: current detection unit, 140: voltage detection unit, 150: assembled battery control unit, 151: SOC calculation unit, 160: signal communication means, 170: insulation element, 200: vehicle control unit, 300-330: Relay, 400: inverter, 410: motor generator, 420: charger, 500: temperature information processing unit, 510: internal temperature calculation unit, 520: temperature selection unit, 521: CCV calculation unit, 522: pattern determination unit, 523: pattern storage unit, 524: temperature output unit, A to C: first to third magnitude relationship patterns, I: actual charge / discharge current (measured current), T: temperature information, Ti: estimated internal temperature, Tt: true internal temperature, Ts: surface temperature, Ve: estimated charge / discharge voltage (estimated voltage), Vm: actual charge / discharge voltage (measured voltage)

Claims

1. A battery control device that calculates at least temperature information T to calculate an allowable power of a battery, a surface temperature detection unit that measures a surface temperature Ts of the battery; an internal temperature calculation unit that estimates an estimated internal temperature Ti of the battery instead of the actual measurement; a temperature selection unit that selects and outputs either the surface temperature Ts or the estimated internal temperature Ti as the temperature information T; and The temperature selection unit Based on information accumulated over a plurality of time periods, the actual charge / discharge voltage Vm of the battery at a certain time, the actual charge / discharge current I of the battery, and the estimated charge / discharge voltage Ve estimated from the state information of the battery, Regarding the current battery, Under the condition that the surface temperature Ts<the estimated internal temperature Ti, First to third magnitude relationship patterns are defined for the magnitude relationship among the true internal temperature Tt, the surface temperature Ts, and the estimated internal temperature Ti of the battery; In the first magnitude relationship pattern, the estimated internal temperature Ti and the true internal temperature Tt of the battery are estimated to be equal, In the second magnitude relationship pattern, the magnitude relationship among the true internal temperature Tt, the surface temperature Ts, and the estimated internal temperature Ti of the battery is estimated to be Ts<Tt<Ti, In the third magnitude relationship pattern, the magnitude relationship among the true internal temperature Tt of the battery, the surface temperature Ts, and the estimated internal temperature Ti is estimated to be Ts<Ti<Tt, a pattern storage unit that stores one of the first to third magnitude relationship patterns selected based on the information accumulated for the plurality of time periods; a pattern determination unit that determines which of the first to third magnitude relationship patterns stored in the pattern storage unit the current magnitude relationship of the battery corresponds to; a temperature output unit that selects and outputs the temperature information T according to the result of the determination by the pattern determination unit; Equipped with The temperature output unit If it is determined that the first or third magnitude relationship pattern is true, the estimated internal temperature Ti is selected and output as the temperature information T; If it is determined that the second magnitude relationship pattern is true, the surface temperature Ts is selected and output as the temperature information T. Battery control device.

2. the first magnitude relationship pattern held by the pattern holding unit corresponds to a case where, among the information accumulated for the plurality of time periods, a maximum value |ΔV|max of the absolute value of the difference between the actual charge-discharge voltage Vm and the estimated charge-discharge voltage Ve is equal to or smaller than a predetermined value ΔVth; The second magnitude relationship pattern and the third magnitude relationship pattern correspond to a case where, among the information accumulated for the plurality of time periods, a maximum value |ΔV|max of the absolute value of the difference between the actual charge / discharge voltage Vm and the estimated charge / discharge voltage Ve exceeds the predetermined value ΔVth. The battery control device according to claim 1 .

3. The second magnitude relationship pattern and the third magnitude relationship pattern stored in the pattern storage unit are The determination is made based on a combination of the magnitude relationship between the estimated charge / discharge voltage Ve and the actual charge / discharge voltage Vm and the polarity of the actual charge / discharge current I among the information accumulated for the plurality of time periods. The battery control device according to claim 2 .

4. The second magnitude relationship pattern is a magnitude relationship pattern that corresponds to a case where, when the actual charging / discharging current I is charging, the estimated charging / discharging voltage Ve tends to be lower than the actual charging / discharging voltage Vm, and, when the actual charging / discharging current I is discharging, the estimated charging / discharging voltage Ve tends to be higher than the actual charging / discharging voltage Vm. The battery control device according to claim 3 .

5. The third magnitude relationship pattern is a magnitude relationship pattern that corresponds to a case where, when the actual charging / discharging current I is charging, the estimated charging / discharging voltage Ve tends to be higher than the actual charging / discharging voltage Vm, and, when the actual charging / discharging current I is discharging, the estimated charging / discharging voltage Ve tends to be lower than the actual charging / discharging voltage Vm. The battery control device according to claim 3 .

Images