JP5845998B2 - Secondary battery charge equivalent amount calculation device - Google Patents

Description

  The present invention uses a detected value of a charge / discharge current of a secondary battery and a detected value of a terminal voltage of the secondary battery as inputs, and calculates a secondary charge amount that is a physical quantity expressing the charged amount of the secondary battery. The present invention relates to a battery charge equivalent amount calculation device.

  2. Description of the Related Art A hybrid vehicle equipped with an internal combustion engine and a rotating machine and performing power generation control using the power of the internal combustion engine in order to keep the charging rate of the secondary battery at a substantially constant value is well known.

  By the way, in recent years, when the vehicle is driven by a rotating machine using a secondary battery as a power source due to the improvement of the energy density of the battery and the response to environmental problems, the driving in the so-called EV mode that stops the internal combustion engine. Hybrid vehicles that enable this are also proposed. In such a hybrid vehicle, in a region where the charging rate of the secondary battery is relatively high, the vehicle is driven in the EV mode, and the charging rate of the secondary battery is lowered, so that the driving in the HV mode in which the internal combustion engine is operated. Become.

  On the other hand, it is known that the charging rate of the secondary battery is determined approximately uniquely according to the open-circuit voltage. For this reason, various methods have been proposed for estimating the open circuit voltage from the closed circuit voltage, which is the terminal voltage when the charge / discharge current amount of the secondary battery is not zero. For example, Patent Document 1 below proposes estimating an open-circuit voltage using a digital filter.

JP 2004-264126 A

  In the HV mode, the charging rate of the secondary battery is normally controlled to a substantially constant value. For this reason, the average current amount of the secondary battery is controlled to be substantially zero on a relatively short time scale. On the other hand, in the EV mode, the average value of the discharge current of the secondary battery can deviate greatly from zero on a considerably long time scale. Under these circumstances, the inventors have found that when the open-circuit voltage is estimated based on the closed-circuit voltage, the estimation accuracy decreases.

  The present invention has been made in the process of solving the above-mentioned problems, and the object thereof is to input a detection value of a charge / discharge current of a secondary battery and a detection value of a terminal voltage of the secondary battery, and input the secondary battery. This is to provide a new charge equivalent amount calculation device for a secondary battery that calculates a charge equivalent amount, which is a physical quantity expressing the amount of charge.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

In the configuration 1, the detection value of the charging and discharging currents of the secondary battery (C11~Cnm) and inputs the detected value of the terminal voltage of the secondary battery, charge corresponding a physical quantity representing the amount of charge of the secondary battery A charge equivalent amount calculating means for calculating an amount, wherein the charge equivalent amount calculating means calculates a history equivalent amount that is a voltage determined according to a history of the charge / discharge current among terminal voltages of the secondary battery. Equivalent amount calculation means (S10 to S16, S20 to S26) are provided, and the history equivalent amount calculation means calculates a long-term history equivalent amount that is a history equivalent amount with a time constant for the detected value of the charge / discharge current of 10 s or more. A long-term history calculating means, and a reducing means (S34) for decreasing the long-term history equivalent amount in accordance with the transition from the continuous charging or discharging state of the secondary battery to a state where the cycle of charging and discharging is less than 10 s, With It is characterized in.

  In a conventional hybrid vehicle or the like, since the average current amount of the secondary battery is controlled to be substantially zero on a relatively short time scale, it is relatively short when removing the influence of polarization from the closed circuit end voltage of the secondary battery. The charge / discharge history on the time scale should be considered. For this reason, it was supposed that the time constant of the means for removing the influence of polarization should be relatively short. On the other hand, if the time constant of the means for removing the influence of polarization is excessively long, the influence of the polarization due to the change in current on a short time scale cannot be sufficiently removed.

  On the other hand, when the average amount of current can deviate from zero in a considerably long time scale, the inventors cannot eliminate the influence of polarization by using a time constant adapted in the short time scale. It was found by. In view of this point, the above invention uses a long-term history equivalent amount having a relatively long time constant.

  However, in the state where the average current amount deviates from zero in the long time scale as the charging / discharging cycle changes from the continuous state of the secondary battery to the state where the period of charging and discharging is less than the time constant corresponding to the long-term history. The effects of what happened gradually disappear. However, depending on the configuration of the long-term history calculation means, the process of eliminating the long-term history may not be expressed appropriately. For this reason, a reduction means is provided.

  In addition, about the expansion of the concept regarding the following typical embodiment concerning this invention, it describes in the column of "other embodiment" after typical embodiment.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows the relationship between the driving modes and charge rate concerning the embodiment. The figure which shows the relationship between the open end voltage of the battery cell concerning the same embodiment, and a charging rate. The circuit diagram of the model of the battery cell concerning the embodiment. The circuit diagram explaining one Example of the calculation method of the polarization voltage based on the model of the embodiment. The figure which shows the map which defined the relationship between the charging rate and model parameter concerning the embodiment. The flowchart which shows the procedure of the calculation process of the polarization voltage concerning the embodiment. The flowchart which shows the procedure of the calculation process of the polarization voltage concerning the embodiment. The flowchart which shows the procedure of the calculation process of the charging rate concerning the embodiment. The time chart which shows the effect of the embodiment. The time chart which shows the calculation result of the charging rate by the comparative example with the embodiment. The time chart which shows the calculation result of the charging rate by the comparative example with the embodiment.

  Hereinafter, an embodiment in which a secondary battery charge equivalent amount calculation apparatus according to the present invention is applied to a plug-in hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The illustrated high voltage battery 10 is an assembled battery as a series connection body of battery cells C11 to Cnm, and has an open end voltage of, for example, 100 V or more. The battery cell Cij (i = 1 to n, j = 1 to m) is a secondary battery such as lithium ion. The battery cells C11 to Cnm have the same configuration except for individual differences. That is, the relationship of the open-circuit voltage with respect to the charging rate (SOC: ratio of the actual charge amount to the full charge amount), the full charge amount, the internal resistance value, and the like are equal to each other.

  The negative electrode potential of the high voltage battery 10 is set to a potential different from the vehicle body potential. Specifically, in the present embodiment, the median value of the positive electrode potential and the negative electrode potential of the high voltage battery 10 is set to be the vehicle body potential. This means that a series connection body of a pair of capacitors and a series connection body of a pair of resistors are connected between the positive electrode and the negative electrode of the high-voltage battery 10, and the connection points of the capacitors or the resistors are connected to the vehicle body. Can be done.

  An AC / DC converter circuit 11 is connected to the high voltage battery 10 via a main relay MR. After the AC power of the commercial power source outside the vehicle is converted into DC power by the AC / DC converter circuit 11, It is input to the battery 10.

  The high voltage battery 10 is connected to the second motor generator 14 via the main relay MR and the inverter 12. The second motor generator 14 is an in-vehicle main machine, and its rotor is mechanically connected to the drive wheels 16.

  The high voltage battery 10 is connected to the first motor generator 20 via the main relay MR and the inverter 18. The rotor of the first motor generator 20 is mechanically connected to the crankshaft 24 of the internal combustion engine 22. The first motor generator 20 functions as conversion means (generator) for converting the power of the crankshaft 24 into electric energy, and initial rotation imparting means for imparting initial rotation to the crankshaft 24 when the internal combustion engine 22 is stopped. Function as a (starter). The internal combustion engine 22 is a means for converting energy accompanying combustion of fuel in the fuel storage means (fuel tank 23) into motive power.

  The battery cells C11 to Cnm constituting the high-voltage battery 10 are modularized with m (> 2) adjacent to each other in the same group. Here, the i-th module includes battery cells Ci1 to Cim.

  Each module is provided with a detection unit Ui (i = 1 to n). The detection units U1 to Un have the same functions. Specifically, as illustrated for the detection unit Un, the discharge resistor 30 and the switching element 32 connected in parallel to each of the battery cells Ci1 to Cim, and the discharge control unit 34 that selectively turns on the switching element 32; It has. Further, a multiplexer 36 that selectively applies one of the terminal voltages of the battery cells Ci1 to Cim to the differential amplifier circuit 38 is provided. Thereby, each terminal voltage (cell voltage Vi1-Vim) of battery cell Ci1-Cim is input into the analog-digital converter 40 via the differential amplifier circuit 38, and is converted into digital data here.

  On the other hand, the control device (battery ECU 52) of the high voltage battery 10 controls the state of the high voltage battery 10 by operating the detection unit Ui. The battery ECU 52 has a function of inputting digital data (cell voltage Vij) output from the analog-digital converter 40 and outputting a command signal Sc to the discharge control unit 34 of the detection unit Ui based on this. Here, the command signal Sc is used to command which of the battery cells Ci1 to Cim is to be discharged using the discharging resistor 30 (and whether to stop the discharge). The battery ECU 52 and the HVECU 50 both use a low voltage battery 54 having a terminal voltage lower than that of the high voltage battery 10 and a vehicle body potential as a reference potential.

  The battery ECU 52 determines the maximum allowable output of the high voltage battery 10 based on the cell voltage Vij, the charge / discharge current I of the high voltage battery 10 detected by the current sensor 56, and the temperature Tij of the battery cell Cij detected by the temperature sensor 58. The information regarding this is sequentially provided to the control device (HVECU 50).

  There are the following four pieces of information. First, there is a charging power boundary value Win10s that is a maximum value that can maintain the charging power of the high-voltage battery 10 for 10s. Secondly, there is a charging power boundary value Win2s that is a maximum value that can maintain the charging power of the high-voltage battery 10 for 2 s. Thirdly, there is a discharge power boundary value Wout10s that is a maximum value that can maintain the discharge power of the high-voltage battery 10 for 10s. Fourth, there is a discharge power boundary value Wout2s that is a maximum value that can maintain the discharge power of the high-voltage battery 10 for 2 s.

  Then, the HVECU 50 controls the control amounts of the first motor generator 20 and the second motor generator 14 based on this information. Specifically, the HVECU 50 appropriately selects the HV mode for driving the internal combustion engine 22 and the EV mode for running with the internal combustion engine 22 stopped by setting the motor generators 14 and 20 and the internal combustion engine 22 as control targets. .

  These HV mode and EV mode are switched according to the state of charge (SOC) of the high-voltage battery 10 as shown in FIG. That is, the vehicle travels in the EV mode in a region where the charging rate is relatively high. This is in view of the fact that fuel combustion energy has a higher energy cost than electric energy charged from a commercial power source. Specifically, the vehicle travels in the EV mode in a region where the EV upper limit charging rate Px is equal to or lower than the EV lower limit charging rate Py. On the other hand, in the region where the charging rate is low (Pz ≦ SOC <Py), the vehicle travels in the HV mode. Here, in the traveling in the HV mode, since the charging rate of the high-voltage battery 10 is lowered, a process of increasing the power generation amount of the second motor generator 14 by the power of the internal combustion engine 22 is performed. As shown, the charging rate is limited between EV lower limit charging rate Py and HV lower limit charging rate Pz. However, even when traveling in the HV mode, for example, when regenerative braking operation is frequently used during downhill traveling, the charging rate of the high-voltage battery 10 is set to the EV lower limit charging rate Py from the viewpoint of energy cost reduction. Control to raise the above is performed.

  Here, as schematically shown in FIG. 2B, a situation in which the charging rate greatly fluctuates occurs, for example, when the accelerator operation amount by the user is maximized. That is, in this case, since the power output from the vehicle to the drive wheels 16 is maximized, the discharge current of the high voltage battery 10 is substantially maximized, and the charging rate of the high voltage battery 10 is also reduced. However, the period during which the accelerator operation amount is maximum is usually less than “10 s”. For this reason, in the HV mode, even when the amount of change in the charging rate increases, the time required for the charging rate to increase after decreasing is about twice the period during which the accelerator operation amount is maximized. It will be a relatively short time. As described above, when the vehicle is traveling in the HV mode, control is performed so as to suppress fluctuations in the charging rate of the high-voltage battery 10, so that the average value of the charge / discharge current is controlled to zero on a relatively short time scale. Has been.

  The battery ECU 52 further performs a process of calculating the charging rate of the high voltage battery 10 based on the detection values of the various sensors. Here, although there is a relationship of FIG. 3 between the open-circuit voltage (OCV) and the charging rate (SOC) of the battery cell Cij, the closed-circuit voltage (cell voltage Vij) and the open-circuit voltage of the battery cell Cij Is different depending on the internal resistance of the battery cell Cij and the history equivalent amount (hereinafter, polarization voltage) corresponding to the charge / discharge history of the battery cell Cij. For this reason, in the present embodiment, the amount of voltage drop due to these internal resistances and the polarization voltage are calculated using the model shown in FIG.

  That is, a battery cell as a series connection body of a power supply having an open-circuit voltage OCV, a resistance body having a resistance value Rs, and a parallel connection body having a resistance value Rk (k = 1, 2, 3) and a capacitor having a capacitance Ck By modeling Cij, the voltage drop amount of the resistor having the resistance value Rs and the polarization voltage are calculated. Here, the polarization voltage is calculated as a voltage drop amount of three parallel connection bodies of resistors and capacitors connected in series.

  Here, in the present embodiment, the time constants R1, C1, R2, C2, R3, and C3 of the parallel connection body of the resistor and the capacitor are different from each other. In particular, the present embodiment is characterized in that the time constant R3 · C3 is set to “10 s” or more. This is for expressing the polarization voltage caused by the average current of the high voltage battery 10 greatly deviating from zero in a relatively long time scale such as the EV mode. That is, in the HV mode, charging and discharging are repeated periodically, so that the average current becomes substantially zero on a relatively short time scale. For this reason, in order to calculate the polarization voltage in the HV mode (a short-term history equivalent amount), a model having a relatively small time constant is required. On the other hand, in the EV mode, a polarization phenomenon depending on the average current in a time scale longer than the charge / discharge cycle in the HV mode occurs. For this reason, a model having a relatively large time constant is required to calculate the polarization voltage (a long-term history equivalent amount) resulting from this polarization phenomenon.

  For this reason, the polarization phenomenon in the HV mode is modeled by the part having the time constants R1, C1, R2, and C2, and the polarization phenomenon in the EV mode is modeled by the part having the time constants R3 and C3. That is, the parallel connection body having the time constants R1, C1, R2, and C2 is used by the short-term history calculating unit in the present embodiment, and the parallel connection body having the time constants R3 and C3 is used in the present embodiment. Used by long-term history calculation means.

  Hereinafter, a method for calculating the polarization voltage using the model shown in FIG. 4 will be described.

  In this embodiment, the backward Euler method is used to calculate the voltage drop amount of the capacitor in the above model in a discrete system. That is, when the capacitor charging voltage V is Taylor-expanded in the first order, the following equation (c1) is established.

V (n) = V (n-1) + Tc. (DV (n) / dt) (c1)
Here, a period Tc of discrete time is used.

  In the above formula (c1), the following formula (c2) is established when the capacitance C of the capacitor, the charge Q (n), and the charge / discharge current I (n) are used.

V (n) = V (n-1) + (Tc / C). (DQ (n) / dt)
V (n) = V (n−1) + (Tc / C) · I (n)
I (n) = (C / Tc) .V (n)-(C / Tc) .V (n-1)
= G * .V (n) -G * .V (n-1) (c2)
Here, “C / Tc” is defined as conductance G *.

  The above formula (c2) can be expressed as the following formula (c3).

I (n) = G * · V (n) + I * (c3)
By using the above equation (c3), the model shown in FIG. 4 can be changed to the model shown in FIG. That is, as shown in FIG. 5B, a capacitor having capacitances C1, C2, and C3 is connected in parallel with a path having conductances GA, GB, and GC, and a path through which currents IA, IB, and IC flow. By doing so, the model shown in FIG. 5A can be generated.

  Hereinafter, in the model shown in FIG. 5A, an equation for calculating the voltage drop amount (polarization voltage Vp) in the parallel connection body of the capacitor and the resistor is derived.

  First, the following expressions (c4) to (c6) are established.

IA = GA. {Vp (n-1) -V2 (n-1)} (c4)
IB = GB. {V2 (n-1) -V3 (n-1)} (c5)
IC = GC. {V3 (n-1) -V0 (n-1)} (c6)
In addition, the following equations (c7) to (c9) are established for the currents IGA, IGB, and IGC flowing through the conductances GA, GB, and GC.

IGA = GA · {Vp (n) −V2 (n)} (c7)
IGB = GB. {V2 (n) -V3 (n)} (c8)
IGC = GC · {V3 (n) −V0 (n)} (c9)
Furthermore, the following formulas (c10) to (c12) are established for the currents IR1, IR2, and IR3 flowing through the resistors having the resistance values R1, R2, and R3.

IR1 = (1 / R1). {Vp (n) -V2 (n)} (c10)
IR2 = (1 / R2). {V2 (n) -V3 (n)} (c11)
IR3 = (1 / R3). {V3 (n) -V0 (n)} (c12)
Here, in the node NA of FIG. 5A, the following equation (c13) is established from Kirchhoff's law.

I + IA-IGA-IR1 = 0 (c13)
Substituting the above formulas (c7) and (c10) into the above formula (c13) and rearranging, the following formula (c14) is established.

I + IA =
Vp (n). {(1 / R1) + GA} + V2 (n). {-(1 / R1) -GA}
... (c14)
Further, in the node NB of FIG. 5A, the following equation (c15) is established from Kirchhoff's law.

-IA + IGA + IR1 + IB-IGB-IR2 = 0 (c15)
Substituting the above formulas (c7), (c10), (c8), and (c11) into the above formula (c15) and rearranging, the following formula (c16) is established.

-IA + IB =
Vp (n) · {− (1 / R1) −GA}
+ V2 (n) · {(1 / R1) + (1 / R2) + GA + GB}
+ V3 (n) · {− (1 / R2) −GB}
... (c16)
Further, in the node NC of FIG. 5A, the following equation (c17) is established from Kirchhoff's law.

-IB + IGB + IR2 + IC-IGC-IR3 = 0 (c17)
Substituting the above formulas (c8), (c11), (c9), and (c12) into the above formula (c17) and rearranging, the following formula (c18) is established.

-IB + IC =
V2 (n). {-(1 / R2) -GB}
+ V3 (n) · {(1 / R2) + (1 / R3) + GB + GC}
... (c18)
From the above equations (c14), (c16), and (c18), the following equations (c19) to (c21) are established.

上記コンダクタンスＧＡ，ＧＢ，ＧＣは、静電容量Ｃ１，Ｃ２，Ｃ３に依存する。そして、静電容量Ｃ１，Ｃ２，Ｃ３や、抵抗値Ｒｓ，Ｒ１，Ｒ２，Ｒ３は、電池セルＣｉｊの充電率や温度、充放電電流に応じて変化する。そこで本実施形態では、図６に示すマップを備えて、静電容量Ｃ１〜Ｃ３や抵抗値Ｒｓ，Ｒ１〜Ｒ３を、充電率や温度、充放電電流に応じて可変設定する。ここで、上記マップは、電池セルに交流の電流を流す際に、その交流電流の実効値や温度、充電率毎に、インピーダンススペクトルを計測し、計測結果に基づき適合されたものである。ちなみに、図示されるように、本実施形態では、時定数Ｃ３・Ｒ３は、時定数Ｃ２・Ｒ２の１０倍以上となっている。

The conductances GA, GB, and GC depend on the capacitances C1, C2, and C3. And electrostatic capacitance C1, C2, C3 and resistance value Rs, R1, R2, R3 change according to the charging rate of battery cell Cij, temperature, and charging / discharging electric current. Therefore, in the present embodiment, the map shown in FIG. 6 is provided, and the capacitances C1 to C3 and the resistance values Rs and R1 to R3 are variably set according to the charging rate, temperature, and charging / discharging current. Here, when the alternating current is supplied to the battery cell, the map is adapted based on the measurement result by measuring the impedance spectrum for each effective value, temperature, and charging rate of the alternating current. Incidentally, as shown in the figure, in this embodiment, the time constant C3 · R3 is 10 times or more the time constant C2 · R2.

  FIG. 7 shows the procedure for calculating the polarization voltage Vp based on the models shown in FIGS. This process is repeatedly executed by the battery ECU 52, for example, at a predetermined cycle.

  In this series of processes, first, in step S10, conductances GA, GB, GC using the capacitances C1 to C3 calculated based on the map shown in FIG. 6 and the cycle Tc of this series of processes. Is calculated. In subsequent step S12, currents IA (n), IB (n), and IC (n) are calculated based on the above equations (c4) to (c6), and the above equations (c22) to (c24) are calculated therefrom. Based on, current values I1 (n), I2 (n), and I3 (n) are calculated.

  In subsequent step S14, the polarization voltage Vp (n) is calculated using the above equations (c19) to (c21). In step S16, the variable n is decremented, and this series of processes is temporarily terminated.

  According to such processing, the polarization voltage Vp (n) of the model shown in FIG. 4 can be calculated, and this and the voltage drop amount Rs · I (n) of the resistor having the resistance value Rs. The charge rate can be calculated assuming that the sum and the open circuit voltage are the cell voltage Vij. And since the model shown in FIG. 4 can express the polarization phenomenon according to the history in the relatively long time scale for the charge / discharge current of the battery cell Cij, the charge rate is calculated with high accuracy in the EV mode. can do.

  However, the inventors have found that the model shown in FIG. 4 has a problem in expressing the state of the battery cell Cij after switching from the EV mode to the HV mode. This is because, according to the above model, the charging voltage of the capacitor having the capacitance C3 depends on the value of the charging voltage in the EV mode even if a long time has elapsed after switching to the HV mode. I guess that. Incidentally, the dependence on the charging voltage in the EV mode occurs because the charging and discharging cycles in the HV mode are shorter than the time constants C3 and R3. On the other hand, for the actual battery cell Cij, after switching to the HV mode, after a while, the influence in the EV mode can be ignored. This means that ignoring the charging voltage of the capacitor having the capacitance C3 expresses the actual polarization voltage or the like with high accuracy.

  Therefore, in the present embodiment, in the HV mode, the model (3RC model) obtained by deleting the time constant C3 / R3 portion (2RC model) is used.

  The polarization voltage Vp (n) based on this model is calculated using the above equation (c16) using the voltage V3 (n) set to V0 (n) = 0 and the above equation (c14). (C25) and (c26).

図８に、２ＲＣモデルに基づく分極電圧Ｖｐの算出処理の手順を示す。この処理は、電池ＥＣＵ５２によって、たとえば所定周期で繰り返し実行される。

FIG. 8 shows a procedure for calculating the polarization voltage Vp based on the 2RC model. This process is repeatedly executed by the battery ECU 52, for example, at a predetermined cycle.

  In this series of processes, first, in step S20, conductances GA and GB are calculated using the capacitances C1 and C2 calculated based on the map shown in FIG. 6 and the period Tc of this series of processes. To do. In the subsequent step S22, currents IA (n) and IB (n) are calculated based on the above equations (c4) and (c5), and the current values I1 (n) and I2 (n) are calculated therefrom. To do. In the subsequent step S24, the polarization voltage Vp (n) is calculated using the above equations (c25) and (c26). In step S26, the variable n is decremented, and this series of processes is temporarily terminated.

  In FIG. 9, the procedure of the calculation process of the charging rate of the battery cell Cij concerning this embodiment is shown. This process is repeatedly executed by the battery ECU 52, for example, at a predetermined cycle.

  In this series of processing, first, in step S30, the cell voltage Vij (n), the charge / discharge current I (n), and the temperature Tij (n) are acquired. In subsequent step S32, the previous calculated value (charge rate SOCij (n-1)) for the charge rate of battery cell Cij is acquired. In a succeeding step S34, either the HV mode or the EV mode is selected based on the charging rate SOCij (n-1). In step S36, whether to use the 2RC model or the 3RC model is selected based on the selection result in the process of step S34. That is, when the HV mode is selected at step S34, the 2RC model is selected at step S36, and when the EV mode is selected at step S34, the 3RC model is selected at step S36.

  The process of step S36 constitutes a reducing unit in the present embodiment. That is, when the EV mode is selected in the previous step S34 and the 3RC model is selected in step S36, when the HV mode is selected in the current step S34, switching to the 2RC model is performed in step S36. The This switching process is equivalent to setting the charging voltage of the capacitor having the capacitance C3 shown in FIG. 4 to zero. That is, this corresponds to the long-term history equivalent amount being corrected to decrease to zero.

  In subsequent step S38, the current charging rate SOCij (n) is temporarily set to the previous charging rate SOCij (n-1). This process is for shortening the convergence time of the charging rate SOCij (n) calculated by the following steps S40 to S46. In the subsequent step S40, the charging rate SOCij (n), temperature Tij (n), and charging / discharging current I (n) are input to the map shown in FIG. Calculate. That is, when the 2RC model is selected, the resistance values Rs, R1, and R2 and the capacitances C1 and C2 are mapped, while when the 3RC model is selected, the resistance values Rs, R1, R2, and R3. And the capacitances C1, C2, and C3 are calculated.

  In subsequent step S42, an estimated value (estimated cell voltage Vije (n)) of cell voltage Vij using the above model is calculated by the following equation (c27).

Vij (n) = − Rs · I (n) + Vp (n) + OCVij (n) (c27)
However, the open circuit voltage OCVij (n) in the above equation (c27) is calculated from the charging rate SOCij (n) and the relationship shown in FIG.

  In a succeeding step S44, it is determined whether or not the absolute value of the difference between the estimated cell voltage Vij (n) and the cell voltage Vij (n) is equal to or less than a specified value ΔVth. This process is for evaluating whether or not the charging rate SOCij (n) is appropriate as indicating the current charging rate. If a negative determination is made in step S44, the process proceeds to step S46, the charge rate SOCij (n) is updated, and the process returns to step S40. On the other hand, when an affirmative determination is made in step S44, the charging rate SOCij (n) at that time is set as the current charging rate of the battery cell Cij, and this series of processes is temporarily ended.

  Here, the processing of steps S40 to S46 is performed in view of the fact that the battery cell Cij has a region where the change rate of the open-circuit voltage becomes small with respect to the change rate of the charge rate, as shown in FIG. It is made with the aim of calculating the value with high accuracy. That is, the charging rate is calculated based on the relationship shown in FIG. 3 from the open-circuit voltage calculated by subtracting “−Rs · I (n)” and the polarization voltage Vp (n) from the cell voltage Vij. In such a case, the calculation accuracy tends to decrease.

  FIG. 10 shows the effect of this embodiment. As shown in the figure, according to the present embodiment, the charging rate SOCij (n) indicated by a solid line in the figure is shown by a broken line in both the EV mode and the HV mode. It can be approximated to a true value.

  On the other hand, when only the 2RC model is used, as shown in FIG. 11, the charging rate SOCij (n) is lower than the true value when traveling in the EV mode. On the other hand, when only the 3RC model is used, as shown in FIG. 12, the charge rate SOCij (n) greatly deviates from the true value when traveling in the HV mode. Incidentally, the traveling in the HV mode shown in FIG. 12 has a period of about 500 s when the charge / discharge balance in one period is slightly positive and slightly negative while the period of charging and discharging is 10 s or less. The pattern repeats with. Here, the deviation of the charge / discharge balance from zero is very small. If the charge voltage of the capacitor C3 in the 3RC model was initially zero, the charge voltage during running in the HV mode is assumed. Is a negligible value. Nevertheless, in FIG. 12, the calculation accuracy of the charging rate SOCij (n) when traveling in the HV mode is reduced because the long-term polarization phenomenon is resolved after the 3RC model is switched from the EV mode to the HV mode. This is thought to be due to the fact that it cannot be expressed correctly.

Incidentally, the charge power boundary values Win10s and Win2s and the discharge power boundary values Wout10s and Wout2s are calculated using the 2RC model or the 3RC model depending on whether the vehicle is traveling in the HV mode or the EV mode. do it. That is, for example, the open circuit voltage OCVij (n) calculated from the charging rate SOCij (n), the voltage drop amount Rs · I (n), and the closed circuit voltage calculated from the polarization voltage Vp (n) is the upper limit voltage. The charging power boundary values Win10s and Win2s may be calculated based on the maximum power value. Further, for example, the discharge power boundary values Wout10s and Wout2s may be calculated based on the maximum power value at which the closed circuit end voltage becomes the lower limit voltage.
<Other embodiments>
The above embodiment may be modified as follows.

About battery cells
The battery cell is not limited to an olivine iron-based lithium ion secondary battery. Furthermore, it is not limited to a lithium ion secondary battery. For example, a nickel hydride secondary battery may be used.

“Charging equivalent amount calculation method”
For example, in the case where the secondary battery for which the charge rate is to be calculated has a change rate of the open end voltage with respect to the change in the charge rate always having a certain magnitude or more, the terminal voltage (closed end voltage) is used. The open circuit voltage may be calculated by subtracting the polarization voltage Vp (n) and adding the voltage drop amount Rs · I (n) due to the internal resistance of the resistance value Rs. In this case, the charging rate can be calculated with high accuracy from the open-circuit voltage.

"About short-term history calculation means"
It is not limited to using a model of a series connection body of a parallel connection body of a resistance body having a resistance value R1 and a capacitor having a capacitance C1, and a parallel connection body of a resistance body having a resistance value R2 and a capacitor having a capacitance C2. For example, a model of a parallel connection of a single resistor and a single capacitor may be used.

  Further, the present invention is not limited to a model using one or a plurality of parallel connection bodies of resistors and capacitors. For example, a model based on an electrochemical reaction equation may be used.

"Long-term history calculation method"
The present invention is not limited to using a model of a parallel connection body of a resistor and a capacitor. For example, a low-pass filter that can be realized by an RC circuit having a time constant of 10 s or more and that has charge / discharge current I (n) as an input, and a map that calculates a long-term history equivalent amount based on the output value of the low-pass filter It may be. However, not limited to this, the main point is that after the secondary battery is charged and discharged, the charge and discharge cycle is less than the long-term history equivalent time constant, and the previous long-term history equivalent amount. If the value of does not converge to zero over time, it is useful to provide a decrementing means.

  In addition, as long-term history calculation means, those described in “About the reduction means” may be used.

"About reduction means"
In the above embodiment, the means for performing the process of switching between the 3RC model and the 2RC model depending on whether the mode is the HV mode or the EV mode is used. However, the present invention is not limited to this. For example, the 2RC model is used when the vehicle is switched to the HV mode while traveling in the EV mode, or when the vehicle is traveling in the HV mode within a time shorter than the time required for eliminating the polarization after the completion of traveling in the EV mode. You may switch to. That is, the 3RC mode may be selected when starting the running in the HV mode after the charge / discharge current I (n) of the high voltage battery 10 has been substantially zero for a long time.

  In addition, for example, when traveling is started in the middle of charging of the high-voltage battery 10 by an external commercial power source, when the HV mode is selected, the 2RC model may be used.

  Furthermore, it is not limited to the one that binaryly switches between the 3RC model and the 2RC model. For example, when switching from the EV mode to the HV mode, the charging rate is calculated by a weighted average process of the charging rate calculated by the 3RC model and the charging rate calculated by the 2RC model. At this time, the charging rate is calculated by the 3RC model. The charging rate weighting factor may be gradually decreased. In this case, assuming that the calculated value of the final charging rate is obtained by the 3RC model alone, if the charge voltage (equivalent to long-term history) of the capacitor having the capacitance C3 is calculated backward, it will gradually decrease. Become.

  In addition, the present invention is not limited to the one provided with a judging means for judging whether or not the charging and discharging cycle is less than 10 s. For example, the long-term history calculating means comprises a map that defines the relationship between the average current value and the polarization voltage, and the average current value that is the input of the map is a moving average having the function of a low-pass filter with a time constant of 10 s or more. The output value of the processing means may be used. In this case, by switching from the EV mode to the HV mode, the average current value gradually converges to zero, and accordingly, the polarization voltage (long-term history equivalent amount) as the output of the map becomes zero.

"History equivalent amount calculation means"
For example, the charge equivalent amount calculation means calculates the open-circuit voltage calculated by the regression line from a plurality of sets of the detected current value (charge / discharge current I (n)) and the cell voltage Vij (n) by the long-term history calculation means. In the case where the correction is made according to the long-term history equivalent amount, the short-term history calculation means may not be provided. That is, the open-circuit voltage calculated by the regression line is obtained by removing the influence of the polarization voltage due to the short-term charge / discharge history.

  In the said embodiment, although resistance value Rs, R1, R2, R3 and electrostatic capacitance C1, C2, C3 were map-calculated based on the charging rate, temperature, and charging / discharging electric current, it is not restricted to this. For example, only two of the charging rate and the temperature may be used as the map input parameters. In addition, when the charging rate is calculated by a method other than the processing of steps S40 to S46 in FIG. 9 on the assumption that the charging rate is an input parameter of the map, the charging rate is determined for the input parameter of the map. Not required. In addition, the dependent variable is not limited to the one using the map, but a function using the charging rate or the like as an independent variable and the resistance values Rs, R1, R2, and R3, and the capacitances C1, C2, and C3 as dependent variables. May be calculated each time.

"About the vehicle"
The hybrid vehicle is not limited to a series hybrid vehicle, and may be a parallel series hybrid vehicle, for example.

  Moreover, it is not limited to a hybrid vehicle, but may be, for example, an electric vehicle on which only a secondary battery is mounted as energy storage means for a rotating machine as an in-vehicle main machine. Even in this case, if the cycle of charging and discharging is less than the time constant corresponding to the long-term history when traveling on a rough road surface, the calculation accuracy of the charging rate can be increased by switching to the 2RC model. Can be improved.

“Information on maximum allowable output of high-voltage battery 10”
It is not restricted to what was illustrated by the said embodiment. For example, it may be a time during which predetermined power can be continuously output.

  DESCRIPTION OF SYMBOLS 10 ... High voltage battery, 52 ... Battery ECU (One Embodiment of the charge equivalent amount calculation apparatus of a secondary battery).

Claims (8)

Charging for calculating a charge equivalent amount, which is a physical quantity representing the amount of charge of the secondary battery, using the detected value of the charge / discharge current of the secondary battery (C11 to Cnm) and the detected value of the terminal voltage of the secondary battery as inputs. A substantial amount calculating means,
The charge equivalent amount calculation means calculates a history equivalent amount calculation means (S10 to S16, S20 to S26) that calculates a history equivalent amount that is a voltage determined according to the charge / discharge current history among the terminal voltages of the secondary battery. )
The history equivalent amount calculation means includes:
Long-term history calculation means for calculating a long-term history equivalent amount that is a history equivalent amount with a time constant of 10 s or more;
When it is determined whether the charging and discharging cycle of the secondary battery is less than the time constant of the long-term history equivalent amount, and when it is determined that it is less than the time constant of the long-term history equivalent amount, the long-term history equivalent amount and reducing means you to zero (S34, S36),
Equipped with a,
The long-term history calculation means models a voltage drop amount of a parallel connection body of a resistor (R3) and a capacitor (C3) as the long-term history equivalent amount,
It said reducing means, by a zero voltage drop of the parallel connection body, the charge equivalent amount calculation apparatus of the secondary battery to the long history corresponding amount, wherein zero and to Rukoto. Charging for calculating a charge equivalent amount, which is a physical quantity representing the amount of charge of the secondary battery, using the detected value of the charge / discharge current of the secondary battery (C11 to Cnm) and the detected value of the terminal voltage of the secondary battery as inputs. A substantial amount calculating means,
The charge equivalent amount calculation means calculates a history equivalent amount calculation means (S10 to S16, S20 to S26) that calculates a history equivalent amount that is a voltage determined according to the charge / discharge current history among the terminal voltages of the secondary battery. )
The history equivalent amount calculation means includes:
Long-term history calculation means for calculating a long-term history equivalent amount that is a history equivalent amount with a time constant of 10 s or more;
Short-term history calculation means for calculating a short-term history equivalent amount that is a history equivalent amount with a time constant of less than 10 s ,
The long-term history calculation means models the voltage drop amount of the first parallel connection body of the first resistor (R3) and the first capacitor (C3) as the long-term history equivalent amount,
The short-term history calculating means models the voltage drop amount of the second parallel connection body of the second resistor (R1, R2) and the second capacitor (C1, C2) as the short-term history equivalent amount,
When it is determined whether the charge and discharge cycle of the secondary battery is less than the time constant corresponding to the long-term history, and the first parallel connection is determined to be less than the time constant corresponding to the long-term history From a state in which the voltage drop amount is calculated by a serial connection body of a body and the second parallel connection body to a state in which the voltage drop amount is calculated by the second parallel connection body without using the first parallel connection body charge equivalent amount calculating device of the secondary battery, wherein the switching Rukoto. Storage means (23) for storing fuel, internal combustion engine (22) for converting combustion energy of the fuel into motive power, conversion means (20) for converting motive power of the internal combustion engine into electric energy, and rotating machine as on-vehicle main machine (14), the EV mode, which is a travel mode in which the internal combustion engine is stopped and the rotating machine is driven, and the charge rate of the secondary battery (C11 to Cnm) is controlled by operating the internal combustion engine and the conversion means. A charge equivalent amount calculation device mounted on a vehicle that selectively performs an HV mode, which is a travel mode limited to a predetermined HV region,
The detected value of the detection value and the secondary battery terminal voltage of the charge and discharge current of the secondary batteries as an input, the charge equivalent amount calculation for calculating a charge amount corresponding a physical quantity representing the amount of charge of the secondary battery With means,
The charge equivalent amount calculation means calculates a history equivalent amount calculation means (S10 to S16, S20 to S26) that calculates a history equivalent amount that is a voltage determined according to the charge / discharge current history among the terminal voltages of the secondary battery. )
The history equivalent amount calculation means includes:
Long-term history calculation means for calculating a long-term history equivalent amount that is a history equivalent amount with a time constant of 10 s or more;
With the switching from the EV mode to the HV mode, reducing means you and the long history significant amount of zero and (S34, S36),
Equipped with a,
The long-term history calculation means models a voltage drop amount of a parallel connection body of a resistor (R3) and a capacitor (C3) as the long-term history equivalent amount,
It said reducing means, by a zero voltage drop of the parallel connection body, the charge equivalent amount calculation apparatus of the secondary battery to the long history corresponding amount, wherein zero and to Rukoto. Storage means (23) for storing fuel, internal combustion engine (22) for converting combustion energy of the fuel into motive power, conversion means (20) for converting motive power of the internal combustion engine into electric energy, and rotating machine as on-vehicle main machine (14), the EV mode, which is a travel mode in which the internal combustion engine is stopped and the rotating machine is driven, and the charge rate of the secondary battery (C11 to Cnm) is controlled by operating the internal combustion engine and the conversion means. A charge equivalent amount calculation device mounted on a vehicle that selectively performs an HV mode, which is a travel mode limited to a predetermined HV region,
The detected value of the detection value and the secondary battery terminal voltage of the charge and discharge current of the secondary batteries as an input, the charge equivalent amount calculation for calculating a charge amount corresponding a physical quantity representing the amount of charge of the secondary battery With means,
The charge equivalent amount calculation means calculates a history equivalent amount calculation means (S10 to S16, S20 to S26) that calculates a history equivalent amount that is a voltage determined according to the charge / discharge current history among the terminal voltages of the secondary battery. )
The history equivalent amount calculation means includes:
Long-term history calculation means for calculating a long-term history equivalent amount that is a history equivalent amount with a time constant of 10 s or more;
Short-term history calculation means for calculating a short-term history equivalent amount that is a history equivalent amount with a time constant of less than 10 s ,
The long-term history calculation means models the voltage drop amount of the first parallel connection body of the first resistor (R3) and the first capacitor (C3) as the long-term history equivalent amount,
The short-term history calculating means models the voltage drop amount of the second parallel connection body of the second resistor (R1, R2) and the second capacitor (C1, C2) as the short-term history equivalent amount,
In the EV mode, the history equivalent amount is calculated by a series connection body of the first parallel connection body and the second parallel connection body. In the HV mode, the second parallel connection is not used without using the first parallel connection body. A device for calculating a charge equivalent amount of a secondary battery, wherein the history equivalent amount is calculated by a body .   The history equivalent amount calculating means calculates the voltage drop amount by a series connection body of the first parallel connection body and the second parallel connection body during the switching, and the first parallel connection body. The voltage drop amount is calculated by a weighted average process with the state in which the voltage drop amount is calculated by the second parallel connection without using,
  The charge equivalent amount calculation device according to claim 2, wherein a weighting factor of the voltage drop amount calculated by a series connection body of the first parallel connection body and the second parallel connection body is gradually reduced.   The history equivalent amount calculation means calculates the voltage drop amount by a series connection body of the first parallel connection body and the second parallel connection body when switching from the EV mode to the HV mode. The voltage drop amount is calculated by weighted average processing with the state in which the voltage drop amount is calculated by the second parallel connection body without using the first parallel connection body,
  The charge equivalent amount calculation device according to claim 4, wherein a weighting factor of the voltage drop amount calculated by a series connection body of the first parallel connection body and the second parallel connection body is gradually reduced. The history corresponding amount calculating means, according to claim 1, characterized in that it comprises a short-term history calculation means for calculating a short-term history significant amount time constant is history corresponding amount less than 10s for the detection value of the charging and discharging current or 4. The secondary battery charge equivalent amount calculation device according to 3 , wherein The secondary battery includes a storage means (23) for storing fuel, an internal combustion engine (22) for converting combustion energy of the fuel into power, a conversion means (20) for converting power of the internal combustion engine into electric energy, and It is mounted on a vehicle equipped with a rotating machine (14) as an in-vehicle main machine,
The vehicle includes travel control means (S34) that selectively performs travel in the EV mode and travel in the HV mode,
The EV mode is a traveling mode in which the internal combustion engine is stopped and the rotating machine is driven,
The HV mode, according to claim 1 or 2, characterized in that the running mode to limit the internal combustion engine and HV area a predetermined charging rate of the conversion means and the secondary battery by operating the Secondary battery charge equivalent amount calculation device.

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