JP6534846B2 - Secondary battery charge control device and secondary battery charge control method - Google Patents

Description

  The present invention relates to a secondary battery charge control device and a secondary battery charge control method.

  Conventionally, when controlling the charge state of a secondary battery such as a lead storage battery mounted in a vehicle, as disclosed in, for example, Patent Document 1, the charging rate SOC (State of Charge) of the secondary battery is calculated; Control is performed such that the calculated charging rate SOC falls within the range of predetermined upper and lower limits.

International Publication No. 2012/120932

  By the way, the deterioration of the secondary battery is caused not only by sulfation due to secular change but also dropout of the electrode due to repeated charge and discharge, and stratification of the electrolytic solution. The technology disclosed in Patent Document 1 describes that the SOC upper limit value and the lower limit value are adjusted according to the secular change, but there is a problem that deterioration due to other than the secular change is not targeted. Further, as disclosed in Patent Document 1, there is also a problem that restarting the engine may become difficult when the lower limit value is lowered according to the secular change.

  An object of the present invention is to provide a secondary battery charge control device and a secondary battery charge method capable of reliably starting an engine of a vehicle and coping with deterioration other than aging.

In order to solve the above-mentioned subject, in the rechargeable battery charge control device which controls the charge condition of the rechargeable battery carried in vehicles, in the present invention, SOH estimating which estimates SOH (State of Health) of the rechargeable battery Means, SOC upper limit finding means for finding the SOC (State of Charge) upper limit value of the secondary battery from the SOH estimated by the SOH estimation means, and SOH estimated by the SOH estimation means SOC lower limit value finding means for finding the SOC lower limit value of the secondary battery, SOC estimation means for estimating the SOC of the secondary battery, and the SOC estimated by the SOC estimation means is the SOC upper limit value The secondary battery is charged so as to fall within the range of the SOC upper limit value found by the finding means and the SOC lower limit value found by the SOC lower limit value finding means A charging control means for control, and the SOC upper limit value is a function related to the diffusion control, the SOC lower limit value is characterized by having a a function, related to the voltage drop at the start of the engine of the vehicle .
According to such a configuration, it is possible to reliably start the engine of the vehicle and to cope with deterioration other than aging.

Further, the present invention is characterized in that the SOC upper limit value is a function monotonously increasing with respect to the SOH, and the SOC lower limit value is a function monotonously decreasing with respect to the SOH.
According to such a configuration, it is possible to accurately obtain the SOC lower limit value and the SOC upper limit value according to the SOH.

Further, the present invention is characterized in that the SOC upper limit value is a function convex upward or downward, and the SOC lower limit value is a function convex upward or downward.
According to such a configuration, it is possible to accurately obtain the SOC lower limit value and the SOC upper limit value according to the change in SOH.

によって表されることを特徴とする。
このような構成によれば、拡散律速に基づいてＳＯＣ上限値を精度良く求め、充電を効率良く実行することができる。 Further, the present invention function for the diffusion rate-determining, C _CA represents charge acceptance quantity of electricity, n represents the number of reaction electrons, F represents the Faraday constant, C _Rb represents a reducing substance concentration, A is very In the case where the contact area of the plate and the electrolyte is shown, D _R indicates the diffusion coefficient, t indicates the charging time, and the reducing substance concentration C _R b is a function having the SOC and the SOH as variables,

It is characterized by being represented by
According to such a configuration, the SOC upper limit value can be accurately obtained based on the diffusion rate control, and charging can be performed efficiently.

によって表されることを特徴とする。
このような構成によれば、電圧降下に基づいてＳＯＣ下限値を精度良く求め、エンジンを確実に再始動することができる。 Further, according to the present invention, as for the function relating to the voltage drop at the start, SOF (State of Function) indicates the discharge capacity of the secondary battery, I _C indicates the cranking current at engine start, and R _Z indicates the above When the internal resistance of the secondary battery is shown, E ₀ is an open circuit voltage of the secondary battery, and the internal resistance R _Z is a function having the SOC and the SOH as variables,

It is characterized by being represented by
According to such a configuration, it is possible to accurately determine the SOC lower limit value based on the voltage drop and reliably restart the engine.

Further, the present invention is characterized in that the SOC upper limit value and the SOC lower limit value are corrected according to at least one of the temperature of the secondary battery and the amount of electrolyte solution.
According to such a configuration, even when the temperature and the amount of electrolyte change, the SOC upper limit value and the SOC lower limit value can be corrected to optimal values, and charge control can be performed reliably.

Further, according to the present invention, there is provided a secondary battery charge control method for controlling a charge state of a secondary battery mounted on a vehicle, comprising: SOH estimation step of estimating SOH (State of Health) of the secondary battery; An SOC upper limit value determining step of determining an SOC (State of Charge) upper limit value of the secondary battery from the SOH estimated in step; and an SOC of the secondary battery from the SOH estimated in the SOH estimating step An SOC lower limit value determining step for determining a lower limit value, an SOC estimation step for estimating the SOC of the secondary battery, and the SOC estimated in the SOC estimation step is determined in the SOC upper limit value determining step said SOC upper limit value that is, prior to fall within the scope of the SOC lower limit value issued determined in the SOC lower limit Motomede step Anda charging control step controls the charging of the secondary battery, the SOC upper limit value is a function related to the diffusion control, the SOC lower limit value is a function related to the voltage drop at the start of the engine of the vehicle, that It features.
According to such a method, it is possible to reliably start the engine of the vehicle and to cope with deterioration other than aging.

  According to the present invention, it is possible to provide a secondary battery charge control device and a secondary battery charge method capable of reliably starting an engine of a vehicle and coping with deterioration other than aging.

It is a figure showing an example of composition of a rechargeable battery charge control device concerning an embodiment of the present invention. It is a block diagram which shows the detailed structural example of the control part of FIG. It is a figure which shows the relationship between SOC of a secondary battery, and 10s charge received electricity amount. It is a figure which shows SOC of a secondary battery, and the relationship of SOF. It is a figure which shows SOC upper limit and SOC lower limit which were calculated | required from FIG. 3 and FIG. It is an example of the flowchart for demonstrating the operation | movement of embodiment of this invention. It is a figure which shows an example of SOC upper limit and SOC lower limit which are used in embodiment of this invention.

  Next, an embodiment of the present invention will be described.

(A) Description of the Configuration of an Embodiment of the Present Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a secondary battery charge control device according to an embodiment of the present invention. In this figure, the secondary battery charge control device 1 mainly includes a control unit 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, and a discharge circuit 15, and the charge state of the secondary battery 14 is Control. Here, the control unit 10 refers to the outputs from the voltage sensor 11, the current sensor 12 and the temperature sensor 13 to detect the state of the secondary battery 14 and control the generated voltage of the alternator 16. The charge state of the secondary battery 14 is controlled. The voltage sensor 11 detects the terminal voltage of the secondary battery 14 and notifies the control unit 10 of it. The current sensor 12 detects the current flowing through the secondary battery 14 and notifies the control unit 10 of the current. The temperature sensor 13 detects the ambient temperature of the secondary battery 14 itself or its surroundings, and notifies the control unit 10 of the temperature. The discharge circuit 15 includes, for example, a semiconductor switch and a resistor element connected in series, and the control unit 10 intermittently discharges the secondary battery 14 by the semiconductor switch being on / off controlled.

  The secondary battery 14 is composed of, for example, a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, or a lithium ion battery, and is charged by the alternator 16 to drive the starter motor 18 to start the engine. Power the The alternator 16 is driven by the engine 17, generates alternating current power, converts it into direct current power by the rectification circuit, and charges the secondary battery 14. The alternator 16 is controlled by the control unit 10 and is capable of adjusting the generated voltage. For example, when the vehicle is decelerating, regenerative charging is performed by raising the voltage generated by the alternator 16 to convert kinetic energy of the vehicle into electrical energy and store it in the secondary battery 14.

  The engine 17 is composed of, for example, a reciprocating engine such as a gasoline engine and a diesel engine, or a rotary engine, etc., and is started by the starter motor 18, drives driving wheels via a transmission, and provides propulsion to the vehicle. Drive to generate power. The starter motor 18 is formed of, for example, a direct current motor, generates rotational power by the power supplied from the secondary battery 14, and starts the engine 17. The load 19 includes, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio, a car navigation, and the like, and is operated by the power from the secondary battery 14.

  FIG. 2 is a diagram showing a detailed configuration example of the control unit 10 shown in FIG. As shown in this figure, the control unit 10 includes a central processing unit (CPU) 10a, a read only memory (ROM) 10b, a random access memory (RAM) 10c, a communication unit 10d, and an interface (I / F) 10e. ing. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The ROM 10 b is constituted by a semiconductor memory or the like, and stores the program 10 ba or the like. The RAM 10 c is configured by a semiconductor memory or the like, and stores data generated when the program ba is executed, and parameters 10 ca such as formulas or tables described later. The communication unit 10d communicates with an upper device such as an electronic control unit (ECU) or the like, and notifies the upper device of detected information or control information. The I / F 10e converts the signals supplied from the voltage sensor 11, the current sensor 12 and the temperature sensor 13 into digital signals and takes them in, and also drives the discharge circuit 15, the alternator 16, the starter motor 18 etc. Supply and control these.

(B) Description of Operation of the Embodiment of the Present Invention Next, the operation of the embodiment of the present invention will be described. In the following, after describing the operation principle of the embodiment of the present invention, detailed operation will be described.

  First, the operation principle of this embodiment will be described. FIG. 3 is a diagram showing the relationship between the SOC and the charge acceptance amount of electricity. In this figure, the horizontal axis indicates the SOC [%], and the vertical axis indicates the 10 s charge received electricity amount. Here, the 10 s charge received electricity amount refers to an amount of electricity that the secondary battery 14 can receive when the secondary battery 14 is charged with a predetermined current (for example, several tens A to several hundreds A) for 10 seconds. As] says. In FIG. 3, circles indicate characteristics when the secondary battery 14 is new, squares indicate characteristics when the secondary battery 14 is moderately deteriorated, and triangles indicate when the secondary battery 14 is deteriorated. Show the characteristics of From FIG. 3, regardless of the deterioration state of the secondary battery 14, when the SOC of the secondary battery 14 becomes large, the 10 s charge received electric quantity decreases. In addition, as the secondary battery 14 degrades, the 10 s charge received electricity amount decreases.

  For example, when the vehicle is decelerating, when the regenerative charging is performed by raising the voltage of the alternator 16, the regenerative charging time is often within 10 seconds. Further, in order to execute regenerative charging efficiently, it is desirable that the power generated by the alternator 16 be charged to the secondary battery 14 without leakage. Therefore, when the "desired charge acceptance electric quantity" is the electric quantity generated by the alternator 16 at the time of regeneration, the 10s charge acceptance electric quantity of the secondary battery 14 is the desired charge acceptance electric quantity shown by the dashed dotted line in FIG. It is desirable to be more than the amount. In order to satisfy such conditions, it is necessary to set the SOC to be low according to the deterioration of the secondary battery 14. That is, in order to charge the secondary battery 14 without leakage with the power generated by the alternator 16 at the time of regeneration, the 10 s charge acceptance electricity amount needs to be equal to or more than the “desired charge acceptance electricity amount” indicated by a dashed line. In order to satisfy such conditions, the new secondary battery 14 needs to be SOC 11 or less, and the middle-degraded secondary battery 14 needs to be SOC 12 or less, and the degraded secondary battery 14 needs to be SOC 13 It needs to be

  FIG. 4 is a diagram showing the relationship between SOC and SOF. In FIG. 4, the horizontal axis indicates SOC [%], and the vertical axis indicates SOF (State of Function). Here, SOF is the minimum value of the voltage between the terminals of the secondary battery 14 when driving the starter motor 18 (hereinafter referred to as the discharge capacity). As shown in FIG. 4, the SOF also decreases as the SOC decreases, regardless of the state of deterioration of the secondary battery 14. In addition, the curve moves downward in the figure according to the deterioration of the secondary battery 14. Here, if an SOF capable of activating an ECU or the like (for example, the ECU and the engine 17) is indicated by an alternate long and short dash line, the new secondary battery 14 needs to have an SOC of 21 or more in order to obtain this SOF The product secondary battery 14 needs to have an SOC of 22 or more, and the degraded secondary battery 14 needs to have an SOC of 23 or more. That is, as the deterioration of the secondary battery 14 progresses, the SOC for satisfying the SOF that can start the ECU or the like increases.

  FIG. 5 is a diagram summarizing the results of FIGS. 3 and 4. The horizontal axis of FIG. 5 indicates SOH, and the vertical axis indicates SOC. In FIG. 5, triangles and one-dot chain lines indicate SOC values satisfying the desired charge acceptance electric quantity shown in FIG. 3, and square and two-dot chain lines indicate SOC values capable of activating the ECU etc. shown in FIG. . In order for the secondary battery 14 to charge the desired charge acceptance electric quantity without leakage, the SOC needs to be set smaller than the one-dot chain line curve. Further, in order to activate the ECU or the like, the SOC needs to be set larger than the curve of the two-dot chain line. That is, the SOC of the secondary battery 14 is controlled by setting the curve indicated by the alternate long and short dash line as the upper limit (SOC upper limit) and the curve indicated by the alternate long and two short dashes line as the lower limit (SOC lower limit) to start the ECU etc. While being possible, it becomes possible to charge regenerative electric power without leakage.

  In the present embodiment, the control unit 10 first obtains the SOH of the secondary battery 14 at that time. As an example, control unit 10 controls discharge circuit 15 to pulse discharge secondary battery 14, and detects the voltage and current at that time by voltage sensor 11 and current sensor 12 to obtain internal resistance R. it can. Alternatively, the control unit 10 obtains the voltage drop ΔV from the open circuit voltage of the secondary battery 14 before the start of the engine 17 and the voltage value at the start of the engine 17, and the current I at the start of the engine 17 The internal resistance R is obtained from = ΔV / I. Then, the control unit 10 obtains the SOH using the value obtained by performing the temperature correction and the deterioration correction on the internal resistance R as an index.

Next, the control unit 10 applies the obtained SOH to the following equation (1) to obtain the SOC upper limit value. Here, equation (1) is an equation for diffusion control, C _CA represents the charge acceptance quantity of electricity, n represents indicates the number of reaction electrons, F is shows a Faraday constant, C _Rb is a reduced material density, A Indicates the contact area of the electrode plate and the electrolyte, D _R indicates the diffusion coefficient, and t indicates the charging time (regeneration time). The charge acceptance electricity amount _CCA is set based on the desired charge acceptance electricity amount shown in FIG. For example, when the supply capacity of the current at the time of regeneration of the alternator 16 is 150 A and the regeneration time is 10 seconds, 150 × 10 = 1500 [As], which is the product of these, becomes the desired charge acceptance electric quantity . The reducing substance concentration C _Rb is a function having SOC and SOH as variables. The number n of reaction electrons, the Faraday constant F, the contact area A of the electrode plate with the electrolyte, the diffusion coefficient D _R , and the charging time t are constants. Therefore, the substituting desired charge acceptance electric quantity as the charge acceptance electricity quantity C _CA, the number of reaction electrons n, Faraday constant F, the contact area A of the electrode plate and electrolyte, the diffusion coefficient D _R, and the charging time t Substitute a predetermined value as. Also, the value of SOH at that time is substituted for SOH which is one of the variables of the reducing substance concentration C _R b. Then, the SOC upper limit value is obtained by obtaining the value of SOC, which is the other variable of the reducing substance concentration _CRb .

・・・（１）

... (1)

Next, the control unit 10 obtains the SOC lower limit value from the following equation (2). Here, the equation (2) is an equation relating to the voltage drop when starting the engine 17, and the SOF indicates the SOF which can be activated by the ECU or the like shown in FIG. Further, I _C indicates a cranking current, R _Z indicates an internal resistance of the secondary battery 14, and E ₀ indicates an open circuit voltage of the secondary battery 14. The cranking current I _C indicates the current flowing to the starter motor 18 when the engine 17 is cranked (started) by the starter motor 18. The internal resistance R _Z is an internal resistance of the secondary battery 14 and is a function having SOC and SOH as variables. Control unit 10 substitutes the value of SOF which can start the ECU etc. shown in FIG. 4 into SOF on the left side of equation (2), and also the measured value of cranking current or the predetermined value determined by engine 17 and starter motor 18 The value of the cranking current as is substituted for I _C on the right side of equation (2). Also, for example, the open circuit voltage measured when the engine 17 is stopped or a predetermined value is substituted into E ₀ on the right side of the equation (2). Furthermore, the value of SOH at that time is substituted for SOH which is one of the variables in R _Z which is a function having SOH and SOC as variables. Then, by obtaining the SOC value of which is the other variables of the internal resistance R _Z, to obtain the SOC lower limit.

・・・（２）

... (2)

  The control unit 10 executes correction processing based on the temperature and the amount of the electrolytic solution with respect to the SOC upper limit value and the SOC lower limit value obtained as described above. That is, since the SOC upper limit value and the SOC lower limit value obtained by the above method are values in the standard state of the secondary battery 14 (the temperature is 25 ° C. and the amount of electrolyte is the reference amount), the temperature and the electrolyte Correction processing is performed based on the amount, and the SOC upper limit value and the SOC lower limit value corresponding to the state at that time are obtained.

  As described above, when the SOC upper limit value and the SOC lower limit value are obtained, the control unit 10 executes charge / discharge control with reference to the SOC upper limit value and the SOC lower limit value. More specifically, the control unit 10 performs charge control when the detected SOC at that time is smaller than the SOC lower limit value. Further, when the detected SOC at that time is larger than the SOC upper limit value, discharge control is performed. As a result, when the secondary battery 14 is new, charge / discharge control is performed in a range where a triangle is an upper limit value and a square is a lower limit value shown at the right end of FIG. Further, when the secondary battery 14 is a moderately deteriorated product, charge / discharge control is performed in a range in which a triangle shown in the center of FIG. 5 is an upper limit value and a square is a lower limit value. Furthermore, when the secondary battery 14 is a deteriorated product, charge / discharge control is performed in a range in which a triangle is an upper limit value and a square is a lower limit value shown at the left end of FIG.

  As described above, according to the embodiment of the present invention, the SOC upper limit value and the SOC lower limit value are determined by calculation based on SOH which is an index indicating the actual capacity of the secondary battery 14, and the temperature and the electrolyte amount By performing the correction according to the above, the appropriate SOC upper limit value and the SOC lower limit value according to the state of the secondary battery 14 at that time are obtained. Then, by performing charge / discharge control based on the SOC upper limit value thus obtained, for example, the secondary battery 14 can be charged without leakage of electrical energy obtained from the kinetic energy of the vehicle during regenerative charging. As it can, the fuel consumption characteristic can be improved. Further, by performing charge / discharge control based on the SOC lower limit value thus obtained, it is possible to reliably prevent, for example, that the engine 17 can not be restarted even when the secondary battery 14 is deteriorated. . Furthermore, in the present embodiment, since the SOC upper limit value and the SOC lower limit value are calculated based on mathematical expressions, it is possible to obtain an appropriate SOC upper limit value and SOC lower limit value according to the state of the secondary battery 14 at that time. Can.

  Next, an example of the flow of processing executed in the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing an example of processing executed by the CPU 10a shown in FIG. When the process of the flowchart shown in FIG. 6 is started, the following steps are performed. The process illustrated in FIG. 6 is executed by, for example, the program 10 ba illustrated in FIG.

  In step S10, the CPU 10a of the control unit 10 estimates the SOH of the secondary battery 14 at that time. For example, as described above, the CPU 10a controls the discharge circuit 15 to pulse discharge the secondary battery 14, and detects the voltage and current at that time by the voltage sensor 11 and the current sensor 12 to determine the internal resistance R. The SOH is estimated using the value obtained by performing the temperature correction and the deterioration correction on the internal resistance R as an index. Alternatively, the CPU 10a obtains the voltage drop ΔV from the open circuit voltage of the secondary battery 14 before the start of the engine 17 and the voltage value at the start of the engine 17, and R = ΔV from the current I at the start of the engine 17. Determine internal resistance R from / I. Then, the control unit 10 estimates the SOH using the value obtained by performing the temperature correction and the deterioration correction on the internal resistance R as an index.

  In step S11, the CPU 10a acquires a desired charge acceptance electricity amount (see FIG. 3). More specifically, the CPU 10a acquires a desired charge acceptance electric quantity from, for example, the parameter 10ca stored in the RAM 10c.

  In step S12, the CPU 10a acquires an SOF (see FIG. 4) capable of activating an ECU or the like. More specifically, the CPU 10a acquires, for example, an SOF that can activate an ECU or the like from the parameter 10ca stored in the RAM 10c.

In step S13, the CPU 10a substitutes the SOH obtained in step S10 into the aforementioned equation (1) to obtain the SOC upper limit value. More specifically, the CPU 10a substitutes the SOH obtained in step S10 as one of the variables of the reducing substance concentration C _Rb of the equation (1), and the number n of reaction electrons from the parameter 10ca stored in the RAM 10c, the Faraday constant F, contact area A of electrode plate and electrolyte, diffusion coefficient D _R , and charging time t are obtained and substituted into equation (1) to determine the value of SOC, which is the other variable of reducing agent concentration C _Rb . Thereby, the SOC upper limit value is obtained.

In step S14, the CPU 10a substitutes the SOH determined in step S10 into the above-described equation (2) to determine the SOC lower limit value. More specifically, the CPU 10a substitutes the SOH obtained in step S10 as one of the variables of the internal resistance R _{Z in} the equation (2), and at the same time, measures the cranking current I _C and the open circuit voltage E ₀ . substituted into (2), obtaining the SOC value of which is the other variables of the internal resistance _{R Z.} Thereby, the SOC lower limit value is obtained.

  In step S15, the CPU 10a detects the temperature of the secondary battery 14 at that time and the amount of electrolytic solution. More specifically, the CPU 10 a detects the temperature of the secondary battery 14 with reference to the output of the temperature sensor 13. Further, the CPU 10a estimates the amount of electrolytic solution of the secondary battery 14 based on the value obtained by cumulatively adding the temperature of the temperature sensor 13. It should be noted that the estimation of the amount of electrolytic solution may be estimated by a method other than that described above.

  In step S16, the CPU 10a executes a process of correcting the SOC upper limit value and the SOC lower limit value in accordance with the temperature of the secondary battery 14 detected in step S15 and the amount of electrolytic solution. More specifically, the CPU 10a stores the SOC upper limit value and the SOC lower limit value based on a table indicating the relationship between the SOC upper limit value and the temperature and the SOC lower limit value and the temperature stored as the parameter 10ca in the RAM 10c. Correct each one. Further, the CPU 10a respectively stores the upper limit value and the lower limit value based on a table stored in the RAM 10c as a parameter 10ca and showing the relationship between the SOC upper limit value and the electrolytic solution amount and the relationship between the SOC lower limit value and the electrolytic solution amount. to correct.

  In step S17, the CPU 10a detects the SOC of the secondary battery 14 at that time. For example, after a predetermined time has elapsed since the engine 17 was stopped, the CPU 10a detects the open circuit voltage of the secondary battery 14, and obtains the SOC based on the relational expression indicating the relationship between the open circuit voltage and the SOC. Of course, the SOC may be determined by other methods.

  In step S18, the CPU 10a compares the SOC obtained in step S17 with the SOC lower limit value corrected in step S16, and proceeds to step S19 if the SOC is smaller than the SOC lower limit value (step S18: Yes). In the case other than that (step S18: No), it progresses to step S20.

  In step S19, the CPU 10a executes charge control. More specifically, the CPU 10a performs a process of charging the secondary battery 14 by adjusting the output voltage of the alternator 16 to increase the inflow current to the secondary battery 14.

  In step S20, the CPU 10a compares the SOC obtained in step S17 with the SOC upper limit value corrected in step S16. If the SOC is larger than the SOC upper limit value (step S20: Yes), the process proceeds to step S21. Otherwise (step S20: No), the process proceeds to step S22.

  At step S21, the CPU 10a executes discharge control. More specifically, the CPU 10a adjusts the output voltage of the alternator 16 to increase the outflow current from the secondary battery 14, thereby executing a process of discharging the secondary battery 14.

  In step S22, the CPU 10a determines whether or not to repeat the process, and if it is determined to repeat the process (step S22: Yes), the process returns to step S10 and repeats the same process, otherwise (step S22). : No) ends the process.

  According to the above processing, the SOC upper limit value and the SOC lower limit value are obtained from the SOH of the secondary battery 14, and the charge / discharge process of the secondary battery 14 is executed with reference to the SOC upper limit value and the SOC lower limit value. Regeneration charging can be performed efficiently regardless of the state of deterioration of the battery 14, and it is possible to prevent the engine 17 from being difficult to restart. Further, since the SOC upper limit value and the SOC lower limit value are obtained from SOH indicating the actual capacity of the secondary battery 14, control can be performed in response to deterioration other than aging of the secondary battery 14.

(C) Description of Modified Embodiments It goes without saying that the above embodiment is an example, and the present invention is not limited only to the case as described above. For example, in the above embodiments, the SOC upper limit value and the SOC lower limit value are calculated using the equations (1) and (2), but the SOC upper limit value and the SOC lower limit value are calculated based on equations other than these You may do so. Also, instead of using a calculation formula, for example, a table in which the SOH value is associated with the SOC upper limit value and the SOC lower limit value is stored as the parameter 10 ca in the RAM 10 c, for example, and this table is referred to. Thus, the SOC upper limit value and the SOC lower limit value may be obtained.

  In the above embodiment, the SOC upper limit value and the SOC lower limit value as shown in FIG. 5 are described as an example, but for example, the SOC upper limit value and the SOC lower limit value as shown in FIG. It is also good. In the example of FIG. 5, the SOC upper limit has an upwardly convex shape, and the SOC lower limit also has an upwardly convex shape. In the example of FIG. 7, the SOC upper limit is downwardly convex. And the SOC lower limit has an upwardly convex shape. Of course, depending on the type of secondary battery 14 or vehicle, the SOC upper limit may be convex upward or downward, or the SOC lower limit may be convex upward or downward.

  Further, in the above embodiments, fixed values are used for both the desired charge acceptance electric quantity and the SOF that can start the ECU etc. However, at least one of these may be used as a fluctuation value that fluctuates depending on the application and environment. Good. For example, the regeneration time may be determined based on the past travel history, and the desired charge acceptance electric quantity may be adjusted according to the determined regeneration time. More specifically, when the regeneration time is short, the value of the desired charge acceptance electric quantity may be correspondingly reduced. In addition, also for the SOF that can start the ECU or the like, the current flowing to the starter motor 18 may be detected at the time of start-up, and the SOF may be adjusted based on the detected current. More specifically, when the current is increased compared to the past start, the SOF that can start the ECU or the like may be increased.

  In the above embodiments, the contact area A between the electrode plate of the formula (1) and the electrolyte is a fixed value, but when the sulfation of the secondary battery 14 progresses or the amount of the electrolyte changes Since it is assumed that the contact area A between the electrode plate and the electrolyte changes, the value of A may be adjusted in such a case.

  In the above embodiments, the SOC upper limit value and the SOC lower limit value are corrected according to the temperature and the amount of the electrolytic solution, but at least one of them may not be corrected. For example, even if the expected change amounts of the temperature and the electrolyte amount are taken into the SOC upper limit value and the SOC lower limit value as a margin and correction is not performed by using such SOC upper limit value and SOC lower limit value Good.

  Further, in the above embodiment, as charge and discharge control using the SOC upper limit value and the SOC lower limit value, discharge control is performed when the SOC upper limit value is exceeded, and charge control is performed when the SOC lower limit value is exceeded. Of course, other control may be performed. For example, charge / discharge control may be performed so as to always fall within a range narrower than the SOC upper limit value and the SOC lower limit value.

  In the process shown in FIG. 6, the process is repeatedly performed. For example, the process of FIG. 6 is performed once when the engine 17 is started, and during traveling, the obtained SOC upper limit value and SOC lower limit value are obtained. The charge and discharge process may be performed based on Alternatively, since the temperature of the secondary battery 14 changes in accordance with the traveling of the vehicle, the process of FIG. 6 may be repeated while the vehicle is traveling. In addition, when repeating, not all the processes are repeated, but, for example, the processes after step S15 may be repeated.

  In each of the above embodiments, the secondary battery 14 is charged by adjusting the voltage of the alternator 16. However, the charge of the secondary battery 14 is reduced by reducing the current supplied to the load 19. The current may be increased. Note that, as a method of reducing the current supplied to the load 19, for example, a priority is given according to the type of the load 19, and when the power feeding capability is lowered, power feeding to a load with low priority is given. There are ways to reduce or stop. For example, a priority is given according to the level of contribution to safe driving, and the power supply is reduced or stopped for, for example, a seat heater, air conditioning, defogger, etc. with low priority. You may

1 secondary battery charge control device 10 control unit (SOH estimation means, SOC upper limit value calculation means, SOC lower limit value calculation means, SOC estimation means, charge control means)
10a CPU
10b ROM
10c RAM
10d Display 10e I / F
11 Voltage Sensor 12 Current Sensor 13 Temperature Sensor 14 Secondary Battery 15 Discharge Circuit 16 Alternator 17 Engine 18 Starter Motor 19 Load

Claims (7)

In a secondary battery charge control device for controlling the charge state of a secondary battery mounted in a vehicle,
SOH estimation means for estimating SOH (State of Health) of the secondary battery;
SOC upper limit value extraction means for calculating an SOC (State of Charge) upper limit value of the secondary battery from the SOH estimated by the SOH estimation means;
SOC lower limit value calculation means for calculating the SOC lower limit value of the secondary battery from the SOH estimated by the SOH estimation means;
SOC estimation means for estimating the SOC of the secondary battery;
Within the range between the SOC upper limit value calculated by the SOC upper limit value extraction means and the SOC lower limit value calculated by the SOC lower limit value calculation means, with the SOC estimated by the SOC estimation means Charge control means for performing charge control of the secondary battery so as to be contained in
The SOC upper limit value is a function related to diffusion limitation, and the SOC lower limit value is a function related to voltage drop at engine start of the vehicle.
A secondary battery charge control device characterized in that.   The secondary battery charge control device according to claim 1, wherein the SOC upper limit value is a function monotonously increasing with respect to the SOH, and the SOC lower limit value is a function monotonously decreasing with respect to the SOH. .   The secondary battery charge control device according to claim 1 or 2, wherein the SOC upper limit value is a function convex upward or downward, and the SOC lower limit value is a function convex upward or downward. The function related to the diffusion limitation is C _CA Represents the charge acceptance quantity, n represents the number of reaction electrons, F represents the Faraday constant, C _Rb Indicates the reducing substance concentration, A indicates the contact area between the electrode plate and the electrolyte, D _R Represents a diffusion coefficient, t represents a charging time, and the concentration of the reducing substance C _Rb Is a function having the SOC and the SOH as variables,

The secondary battery charge control device according to claim 1, which is represented by As for the function related to the voltage drop at the start, SOF (State of Function) indicates the discharge capacity of the secondary battery, I _C Indicates the cranking current at engine start, R _Z Indicates the internal resistance of the secondary battery, E ₀ Indicates the open circuit voltage of the secondary battery, the internal resistance R _Z Is a function having the SOC and the SOH as variables,

The secondary battery charge control device according to claim 1 or 4, which is represented by The secondary battery charge according to any one of claims 1 to 5, wherein the SOC upper limit value and the SOC lower limit value are corrected according to at least one of the temperature of the secondary battery and the amount of the electrolytic solution. Control device. In a secondary battery charge control method for controlling a charge state of a secondary battery mounted on a vehicle,
SOH estimation step of estimating SOH (State of Health) of the secondary battery;
An SOC upper limit value determining step for determining an upper limit value of a state of charge (SOC) of the secondary battery from the SOH estimated in the SOH estimating step;
An SOC lower limit calculation step of calculating an SOC lower limit value of the secondary battery from the SOH estimated in the SOH estimation step;
An SOC estimation step of estimating the SOC of the secondary battery;
The SOC estimated in the SOC estimation step is within the range between the SOC upper limit value calculated in the SOC upper limit value calculation step and the SOC lower limit value calculated in the SOC lower limit value calculation step A charge control step of performing charge control of the secondary battery to be within
The SOC upper limit value is a function related to diffusion limitation, and the SOC lower limit value is a function related to voltage drop at engine start of the vehicle.
A secondary battery charge control method characterized in that.

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