JP2017120198A - Secondary battery state of charge calculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a state of charge calculation device that improves the accuracy of estimating the state of charge of a secondary battery.SOLUTION: A secondary battery state of charge calculation device 14 comprises: a charge/discharge current detection unit 21 for detecting the charge/discharge current value of a secondary battery 13; a terminal voltage detection unit 22 for detecting the terminal voltage value of the secondary battery 13; a first estimation unit 23 for integrating charge/discharge current values and estimating a first state of charge; a second estimation unit 24 for estimating a second state of charge on the basis of the open-circuit voltage value vs. state of charge relationship of the secondary battery 13; and a state of charge calculation unit 25 for calculating a third state of charge on the basis of the first state of charge and the second state of charge, each of which is weighted in accordance with the discharge duration of the secondary battery 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a charging rate calculation device that calculates the charging rate of a secondary battery used in, for example, a hybrid vehicle.

  2. Description of the Related Art Conventionally, secondary batteries that can be charged and discharged have been adopted in vehicles such as hybrid vehicles. For example, in order to grasp the cruising range of the vehicle, it is necessary to detect the state of charge (SOC) of the secondary battery.

  Since the charge rate cannot be directly detected, a method for estimating the charge rate using a current integration method (Coulomb count method) or an open-circuit voltage estimation method (sequential parameter method) is known (for example, Patent Document 1). In the current integration method, the charge / discharge current of the secondary battery is detected in time series and the current is integrated to estimate the current integration method charging rate (ASOC: Absolute State of Charge). The open-circuit voltage estimation method estimates an open-circuit voltage method charging rate (RSOC: Relative State of Charge) by estimating the open-circuit voltage of the battery using an equivalent circuit model of the battery.

JP 2005-201743 A

  However, since current sensor errors accumulate in the current integration method, there is room for improvement in the estimation accuracy of the charging rate. In the open-circuit voltage estimation method, a response portion (slow response portion) having a large time constant has a small SN ratio, and it is difficult to estimate parameters sequentially from the viewpoint of observability. For example, when the secondary battery continues to discharge, the terminal voltage decreases with time. After the discharge is stopped, the terminal voltage rises due to the influence of the early response part. Thereafter, the terminal voltage further increases due to the influence of the slow response portion. Thus, for example, when the influence of the slow response is large, for example, when the secondary battery continues to be discharged, the parameter estimation accuracy is lowered, so there is room for improvement in the charging rate estimation accuracy by the open-circuit voltage estimation method.

  The objective of this invention made | formed in view of this situation is providing the charging rate calculation apparatus which improves the estimation precision of the charging rate of a secondary battery.

In order to solve the above problems, a charging rate calculation apparatus according to the first aspect of the present invention provides:
A charge / discharge current detector for detecting a charge / discharge current value of the secondary battery;
A terminal voltage detector for detecting a terminal voltage value of the secondary battery;
A first estimation unit that accumulates the charge / discharge current values and estimates a first charging rate;
A second estimation unit that estimates a second charging rate based on a relationship between an open-circuit voltage value of the secondary battery and a charging rate;
A charge rate calculation unit for calculating a third charge rate based on the first charge rate and the second charge rate each weighted according to the discharge duration of the secondary battery. Features.

Moreover, the charging rate calculation apparatus according to the second aspect of the present invention is:
The charging rate calculation unit preferably increases the weighting for the first charging rate and decreases the weighting for the second charging rate as the discharge duration of the secondary battery increases.

Moreover, the charging rate calculation apparatus according to the third aspect of the present invention is:
When the secondary battery is in a charged state, the charging rate calculation unit preferably sets a weight for the first charging rate and a weight for the second charging rate to predetermined values.

Moreover, the charging rate calculation apparatus according to the fourth aspect of the present invention is:
It is preferable that the charging rate calculation unit determines the time when the decrease of the third charging rate or the terminal voltage value of the secondary battery starts as the starting time of the discharge duration time.

Moreover, the charging rate calculation apparatus according to the fifth aspect of the present invention is:
The charging rate calculation unit weights the first charging rate according to a decrease amount of the third charging rate or a decrease amount of the terminal voltage value of the secondary battery from the calculation time and the second charging rate. It is preferable to weight the charging rate.

Moreover, the charging rate calculation apparatus according to the sixth aspect of the present invention is:
Via a vehicle-mounted network of a vehicle equipped with an alternator for charging the secondary battery, further comprising a communication unit for obtaining control information of the alternator;
The charging rate calculation unit
It is preferable that the time when power generation of the alternator is stopped be determined as the starting time of the discharge duration time.

  According to the charging rate calculation apparatus according to the first aspect of the present invention, each of the first charging rate based on the current integration method and the second charging rate based on the open-circuit voltage estimation method according to the discharge duration time of the secondary battery. Is weighted. For this reason, for example, when the secondary battery continues to be discharged, the estimation error of the third charging rate is reduced, so that the estimation accuracy of the third charging rate is improved.

  According to the charging rate calculation apparatus according to the second aspect of the present invention, as the discharge duration time of the secondary battery increases, the first weighting factor α for the first charging rate is increased and the second charging rate is increased. The second weight coefficient β for is reduced. In this way, as the secondary battery continues to be discharged, the contribution of the open-circuit voltage estimation method, which decreases the charging rate estimation accuracy, is reduced, and the third charging rate estimation accuracy is further improved.

  According to the charging rate calculation apparatus according to the third aspect of the present invention, when the secondary battery is in a charged state, the first weighting factor α and the second weighting factor β are respectively set to predetermined values. For this reason, when the estimation accuracy of the charging rate by the open-circuit voltage estimation method is relatively high, such as when the secondary battery is in a charged state, weighting according to the discharge duration of the secondary battery is stopped, so the third charge The accuracy of rate estimation is further improved.

  According to the charging rate calculation apparatus according to the fourth aspect of the present invention, the discharge start time n, which is the starting time of the discharge continuation state, is the time when the decrease of the third charging rate or the terminal voltage value of the secondary battery starts. Stipulated in In the time zone in which the secondary battery continues to discharge, the true value of the charging rate and the terminal voltage value decrease at a substantially constant time change rate. For this reason, it is possible to determine the discharge start of the secondary battery with high accuracy by determining the decrease in the third charging rate or the terminal voltage value.

  According to the charging rate calculation apparatus according to the fifth aspect of the present invention, the first weighting factor α and the second weighting factor β are determined according to the third charging rate or the decrease amount of the terminal voltage value. Here, the charging rate according to the open-circuit voltage estimation method is likely to be reduced in accuracy when discharging is performed with a large current, compared to when discharging is performed with a small current in a certain discharge duration. Here, the amount of decrease in the third charging rate or the terminal voltage value increases as the discharge current increases during a certain discharge duration. For this reason, for example, a change in charge rate or a change in terminal voltage value is compared with a configuration in which a look-up table indicating a correspondence relationship between discharge durations and coefficients is used as the first look-up table and the second look-up table. That is, since the coefficient is determined in consideration of the magnitude of the discharge current, the estimation accuracy of the third charging rate is further improved.

  According to the charging rate calculation apparatus of the sixth aspect of the present invention, when the power generation stop of the alternator is detected based on the control information of the alternator, the time when the power generation stop of the alternator is detected is set as the starting time of the discharge duration time. As described above, since the power generation stop time of the alternator that can be detected based on the control information of the alternator can be regarded as the discharge start time of the secondary battery, the discharge start of the secondary battery can be determined with high accuracy.

It is a block diagram which shows schematic structure of the storage battery system which concerns on Embodiment 1 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation part which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the charging rate change amount and a coefficient in a 1st look-up table. It is a figure which shows the relationship between the charging rate change amount and a coefficient in a 2nd look-up table. It is a flowchart which shows operation | movement of the charging rate calculation part which concerns on Embodiment 1 of this invention. It is a figure which shows the experimental data of the charging rate estimation by the charging rate calculation apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation part which concerns on Embodiment 2 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows schematic structure of the charging rate calculation part which concerns on Embodiment 3 of this invention.

  Embodiments of the present invention will be described below.

(Embodiment 1)
First, a schematic configuration of a storage battery system 10 according to Embodiment 1 of the present invention will be described with reference to FIG. The storage battery system 10 is mounted on a vehicle such as a hybrid vehicle (HEV vehicle).

  The storage battery system 10 includes an alternator 11, a starter 12, a first secondary battery 13, a charge rate calculation device 14, a second secondary battery 15, a load 16, a first switch 17, 2 switch 18, third switch 19, and control unit 20. Alternator 11, starter 12, first secondary battery 13, second secondary battery 15, and load 16 are connected in parallel.

  The alternator 11 is a generator and is mechanically connected to a vehicle engine. The alternator 11 can generate power by driving the engine. The power generated by the alternator 11 by driving the engine can be supplied to the first secondary battery 13, the second secondary battery 15, and the load 16 by adjusting the output voltage with a regulator. The alternator 11 can generate power by regeneration when the vehicle is decelerated. The electric power regenerated by the alternator 11 can be used to charge the first secondary battery 13 and the second secondary battery 15.

  The starter 12 includes a cell motor, for example, and receives power supply from at least one of the first secondary battery 13 and the second secondary battery 15 to start the vehicle engine.

  The first secondary battery 13 is a secondary battery other than a lead storage battery, such as a lithium ion battery or a nickel metal hydride battery. In the present embodiment, the output voltage of the first secondary battery 13 is substantially the same as the output voltage of the second secondary battery 15 and is, for example, 12V. Alternatively, the output voltage of the first secondary battery 13 may be different from the output voltage of the second secondary battery 15. In such a case, the output voltage of the first secondary battery 13 is adjusted by the DC / DC converter so as to be substantially the same as the output voltage of the second secondary battery 15. The first secondary battery 13 supplies power to the starter 12, the load 16, the ECU, and the like when the engine drive is stopped (idling is stopped), that is, when the power generation by the alternator 11 is stopped. Is possible.

  The charging rate calculation device 14 calculates the charging rate of the first secondary battery 13. Details of the charging rate calculation device 14 will be described later.

  The second secondary battery 15 is a lead storage battery having an output voltage of a nominal voltage of 12 V, for example, and can supply power to the load 16.

  The load 16 is a load 16 including, for example, an audio, an air conditioner, and a navigation system provided in the vehicle, and operates by consuming the supplied power. The load 16 operates by receiving power supply from the first secondary battery 13 and the second secondary battery 15 while the engine drive is stopped, and the alternator 11 and the first secondary battery 13 while the engine is driven. And the power supply from the second secondary battery 15 operates.

  The first switch 17 is a switch connected in series with the starter 12. The first switch 17 connects or disconnects the starter 12 in parallel with other components.

  The second switch 18 is a switch connected in series with the first secondary battery 13. The second switch 18 connects or disconnects the first secondary battery 13 in parallel with other components.

  The third switch 19 is a switch connected in series with the second secondary battery 15 and the load 16. The third switch 19 connects or disconnects the second secondary battery 15 and the load 16 in parallel with other components.

  The control unit 20 is configured to include, for example, an ECU provided in the vehicle, and controls the entire operation of the storage battery system 10. For example, the control unit 20 controls the operations of the first switch 17, the second switch 18, and the third switch 19, respectively, and the alternator 11, the first secondary battery 13, and the second secondary battery. 15, and the first secondary battery 13 and the second secondary battery 15 are charged.

  Next, details of the charging rate calculation device 14 will be described with reference to FIG. The charging rate calculation device 14 includes a charge / discharge current detection unit 21, a terminal voltage detection unit 22, a current integration method estimation unit (first estimation unit) 23, and an open-circuit voltage method estimation unit (second estimation unit) 24. And a charging rate calculation unit 25 and a delay element 26.

  The charge / discharge current detection unit 21 includes, for example, a shunt resistor and the like, and detects the charge / discharge current value i (k) of the first secondary battery 13. Here, k indicates time in discrete time. The charge / discharge current value i (k) is the absolute value of the charge / discharge current. The detected charge / discharge current value i (k) is input as an input signal to the current integration method estimation unit 23 and the open-circuit voltage method estimation unit 24, respectively. The charge / discharge current detection unit 21 is not limited to the above-described configuration, and those having various structures and formats can be appropriately employed.

  The terminal voltage detector 22 detects the terminal voltage value v (k) of the first secondary battery 13. The detected terminal voltage value v (k) is input as an input signal to the current integration method estimation unit 23 and the open-circuit voltage method estimation unit 24, respectively. As the terminal voltage detection unit 22, ones having various structures and formats can be adopted as appropriate.

  The current integration method estimation unit 23 estimates a current integration method charging rate (first charging rate) SOC1 (k). This will be specifically described below. For example, it is assumed that the initial start time of the vehicle (engine) is set to time k = 0, and the state of the first secondary battery 13 is stable and in no load state at time k = 0. In such a case, the terminal voltage value v (0) input from the terminal voltage detection unit 22 can be regarded as the open circuit voltage value OCV (0). For this reason, the current integration method estimation unit 23 uses an OCV-SOC look-up table that shows the relationship between the open voltage and the charging rate of the first secondary battery 13 obtained in advance by experiment or simulation. The charging rate corresponding to the terminal voltage value v (0) regarded as OCV (0) is estimated as the first charging rate SOC1 (0). The first charging rate SOC1 (0) is input to the charging rate calculation unit 25 as an input signal. In addition, at time k ≧ 1, the current integration method estimation unit 23 inputs from the charge / discharge current detection unit 21 to the previous value SOC3 (k−1) of the third charging rate input from the delay element 26 as described later. A value SOC3 (k−1) + i (k) / FCC obtained by adding a value obtained by dividing the charge / discharge current value i (k) divided by the full charge capacity FCC is estimated as the first charge rate SOC1 (k). The estimated first charging rate SOC1 (k) is input to the charging rate calculation unit 25 as an input signal.

  The open-circuit voltage method estimation unit 24 estimates an open-circuit voltage method charge rate (second charge rate) SOC2 (k). Specifically, first, the open-circuit voltage method estimation unit 24 is based on the charge / discharge current value i (k) and the terminal voltage value v (k) input from the charge / discharge current detection unit 21 and the terminal voltage detection unit 22, respectively. For example, each parameter in the equivalent circuit model of the first secondary battery 13 such as a Foster-type RC ladder circuit or a Cowell-type RC ladder circuit is estimated. For example, the open-circuit voltage method estimation unit 24 uses an adaptive filter such as a Kalman filter or a least-squares method, and the like, the capacitance value C (k) of the capacitor, the internal resistance value R (k), and the open-circuit voltage value OCV (k). Is estimated. Here, the open circuit voltage value OCV (k) is calculated by, for example, OCV (k) = v (k) + (i (k) × R (k)). Then, the open-circuit voltage method estimation unit 24 uses an OCV-SOC look-up table that shows a relationship between the open-circuit voltage of the first secondary battery 13 and the charge rate, which is obtained in advance through experiments or simulations, to open-circuit voltage value OCV. The charging rate corresponding to the value of (k) is estimated as the second charging rate SOC2 (k). The estimated second charging rate SOC2 (k) is input to the charging rate calculation unit 25 as an input signal.

  As will be described later, the charging rate calculation unit 25 uses the first charging rate αSOC1 (k) and the second charging rate βSOC2 (k) weighted using the first weighting factor α and the second weighting factor β, respectively. ) To calculate the third charging rate SOC3 (k). In the present embodiment, third charging rate SOC3 (k) is determined as the charging rate of first secondary battery 13 at time k. Details of the charging rate calculation unit 25 will be described later.

  When the third charging rate SOC3 (k) is input from the charging rate calculation unit 25, the delay element 26 inputs the previous value SOC3 (k-1) of the third charging rate to the current integration method estimation unit 23. .

  Next, the details of the charging rate calculation unit 25 will be described with reference to FIG. The charging rate calculation unit 25 includes an evaluation parameter calculation unit 27, a first coefficient determination unit 28, a second coefficient determination unit 29, a first multiplier 30, a second multiplier 31, and an adder. 32.

  The evaluation parameter calculation unit 27 calculates the evaluation parameter P (k) according to the time during which the discharge of the first secondary battery 13 continues (discharge duration). This will be specifically described below.

  First, the evaluation parameter calculation unit 27 accumulates the third charging rate SOC3 input from the adder 32. For example, at time k, the evaluation parameter calculation unit 27 stores the third charging rates SOC3 (k−1), SOC3 (k−2),... Before the time k−1.

Subsequently, the evaluation parameter calculation unit 27 determines whether or not the discharge of the first secondary battery 13 has been started based on the change in the third charging rate SOC3. Here, when the third charging rate SOC3 increases at a certain time (for example, k = 10) and the third charging rate SOC3 decreases at the next time (for example, k = 11), the time k = 11, it can be determined that the discharge of the first secondary battery 13 has started. In the present embodiment, the evaluation parameter calculation unit 27 determines whether the expressions (1) and (2) are satisfied at the time k.
SOC3 (k-3) <SOC3 (k-2) (1)
SOC3 (k-2)> SOC3 (k-1) (2)

  When Expression (1) and Expression (2) are satisfied, the evaluation parameter calculation unit 27 determines that the discharge of the first secondary battery 13 has started at time k-1. When the evaluation parameter calculation unit 27 determines that the discharge of the first secondary battery 13 is started, it sets the time k−1 to the discharge start time (start time of discharge duration) n of the first secondary battery 13.

On the other hand, when at least one of Expression (1) and Expression (2) is not satisfied, the evaluation parameter calculation unit 27 continues to discharge the first secondary battery 13 based on the change in the third charging rate SOC3. It is determined whether or not it is in a discharged state (discharge continuation state). Here, when the third charging rate SOC3 decreases at a certain time (for example, k = 10) and the third charging rate SOC3 decreases at the next time (for example, k = 11), the time k = 11, it can be determined that the discharge of the first secondary battery 13 is continuing. In the present embodiment, the evaluation parameter calculation unit 27 determines whether or not Expression (3) and Expression (4) are satisfied at time k.
SOC3 (k-3)> SOC3 (k-2) (3)
SOC3 (k-2)> SOC3 (k-1) (4)

  When Expression (3) and Expression (4) are satisfied, the evaluation parameter calculation unit 27 determines that the first secondary battery 13 is in the discharge continuation state at time k-1.

Here, when it is determined that the first secondary battery 13 is in the discharge start state or the discharge continuation state at the time k, the evaluation parameter calculation unit 27, as shown in the equation (5), from the discharge start time n to the time k−1. The change amount (decrease amount) of SOC3 is determined as the evaluation parameter P (k).
P (k) = SOC3 (n) −SOC3 (k−1) (5)

  As shown in Expression (5), the evaluation parameter P (k) changes according to the discharge duration of the first secondary battery 13 ((k-1) -n in Expression (5)). Specifically, as the discharge duration increases, the value of the evaluation parameter P (k) increases.

  Then, after calculating the evaluation parameter P (k), the evaluation parameter calculation unit 27 inputs the evaluation parameter P (k) to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  On the other hand, when at least one of Expression (3) and Expression (4) is not satisfied, the evaluation parameter calculation unit 27 determines that the first secondary battery 13 is in the charged state at time k-1. Then, the evaluation parameter calculation unit 27 inputs information indicating that the first secondary battery 13 is in a charged state to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  Based on the input signal from evaluation parameter calculation unit 27, first coefficient determination unit 28 determines a first weighting factor α to be multiplied by first charging rate SOC1 (k). This will be specifically described below.

  When the evaluation parameter P (k) is acquired from the evaluation parameter calculation unit 27, the first coefficient determination unit 28 is a first lookup table that shows a predetermined relationship between the evaluation parameter P (k) and the coefficient. Is used to determine the coefficient corresponding to the evaluation parameter P (k) as the first weighting coefficient α. Details of the first lookup table will be described later.

  On the other hand, when information indicating that the first secondary battery 13 is in the charged state is acquired from the evaluation parameter calculation unit 27, the first coefficient determination unit 28 sets the predetermined value C1 as the first weighting coefficient α. . The predetermined value C1 is a value determined such that the sum of the predetermined value C1 and the predetermined value C2 described later becomes 1, and is arbitrarily determined within a range of 0 ≦ C1 ≦ 1. Preferably, the predetermined value C1 is a value within a range of 0 ≦ C1 <0.5. More preferably, the predetermined value C1 = 0. Thus, during charging of the first secondary battery 13, the first weighting coefficient α = C1.

  Based on the input signal from evaluation parameter calculation unit 27, second coefficient determination unit 29 determines a second weighting factor β by which to multiply second charging rate SOC2 (k). This will be specifically described below.

  When the evaluation parameter P (k) is acquired from the evaluation parameter calculation unit 27, the second coefficient determination unit 29 determines a predetermined second lookup table indicating the relationship between the evaluation parameter P (k) and the coefficient. Is used to determine the coefficient corresponding to the evaluation parameter P (k) as the second weighting coefficient β. Details of the second lookup table will be described later.

  On the other hand, when the information indicating that the first secondary battery 13 is in the charged state is acquired from the evaluation parameter calculation unit 27, the second coefficient determination unit 29 sets the predetermined value C2 as the second weighting coefficient β. . The predetermined value C2 is a value determined such that the sum of the predetermined value C1 and the above-described predetermined value C1 is 1, and is arbitrarily determined within a range of 0 ≦ C2 ≦ 1. Preferably, the predetermined value C2 is a value within a range of 0.5 <C2 ≦ 1. More preferably, the predetermined value C2 = 1. Thus, during charging of the first secondary battery 13, the second weighting coefficient β = C2.

  Here, the first lookup table and the second lookup table will be described with reference to FIG. 4 and FIG.

  FIG. 4 is a graph showing the relationship between the evaluation parameter P (k) and the coefficient in the first lookup table. In FIG. 4, the horizontal axis represents the evaluation parameter P (k), and the vertical axis represents the coefficient. As illustrated, in the first lookup table, the larger the evaluation parameter P (k), the larger the value of the corresponding coefficient. That is, when the evaluation parameter P (k) increases as the discharge duration of the first secondary battery 13 increases, the weighting of the first charging rate SOC1 (k) estimated by the current integration method increases.

  On the other hand, FIG. 5 is a graph showing the relationship between the evaluation parameter P (k) and the coefficient in the second lookup table. In FIG. 5, the horizontal axis indicates the evaluation parameter P (k), and the vertical axis indicates the coefficient. As illustrated, in the second lookup table, the larger the evaluation parameter P (k), the smaller the value of the corresponding coefficient. That is, when the evaluation parameter P (k) increases as the discharge duration of the first secondary battery 13 increases, the weight of the second charging rate SOC2 (k) estimated by the open-circuit voltage estimation method decreases.

  Further, in the first look-up table and the second look-up table, the relationship between the current or charge / discharge rate and the coefficient so that the sum of the coefficients determined for each arbitrary evaluation parameter P (k) is 1. Is determined. Therefore, the sum of the first weighting coefficient α and the second weighting coefficient β determined for the charge / discharge current value i (k) is always 1. Here, the correspondence relationship between the evaluation parameter P (k) and the coefficient in the first lookup table and the second lookup table is not limited to the correspondence relationship shown in FIGS. 4 and 5, but is arbitrarily determined. It is done. For example, the coefficient may be changed stepwise (non-continuously) according to the evaluation parameter P (k).

  The first multiplier 30 shown in FIG. 3 calculates a weighted first charging rate αSOC1 (k) by multiplying the first charging rate SOC1 (k) by the determined first weighting factor α. To do.

  The second multiplier 31 multiplies the second charging rate SOC2 (k) by the determined second weighting factor β to calculate a weighted second charging rate βSOC2 (k).

As shown in Expression (6), the adder 32 calculates the sum of the weighted first charging rate αSOC1 (k) and the weighted second charging rate βSOC2 (k) as the third charging rate SOC3 ( k).
SOC3 (k) = αSOC1 (k) + βSOC2 (k) (6)

  Next, the operation of the charging rate calculation unit 25 of the charging rate calculation device 14 will be described with reference to the flowchart shown in FIG. This operation is started at an arbitrary time during the operation of the vehicle, for example. Here, it is assumed that charging rate calculation unit 25 stores third charging rate SOC3 before time k−1 at time k.

  Step S100: First, the evaluation parameter calculation unit 27 determines whether or not the discharge of the first secondary battery 13 is started based on the change in the third charging rate SOC3. Specifically, when the above-described equations (1) and (2) are satisfied (step S100—Yes), the evaluation parameter calculator 27 starts discharging the first secondary battery 13 at time k−1. The process proceeds to step S101. On the other hand, when at least one of Expression (1) and Expression (2) is not satisfied (Step S100-No), the process proceeds to Step S102.

  Step S101: When it is determined in step S100 that the discharge of the first secondary battery 13 is started (step S100-Yes), the evaluation parameter calculation unit 27 sets the time k-1 to the discharge start time of the first secondary battery 13. n, and the process proceeds to step S103.

  Step S102: On the other hand, when it is not determined in step S100 that the discharge of the first secondary battery 13 is started (step S100-No), the evaluation parameter calculation unit 27 determines whether the first charging rate SOC3 is changed based on the first charge rate SOC3. It is determined whether or not the secondary battery 13 is in a discharge continuation state. Specifically, when the above-described equations (3) and (4) are satisfied (step S101—Yes), the evaluation parameter calculation unit 27 indicates that the first secondary battery 13 is in a discharge continuation state at time k−1. And the process proceeds to step S103. On the other hand, when at least one of Expression (3) and Expression (4) is not satisfied (Step S101-No), the evaluation parameter calculation unit 27 determines that the first secondary battery 13 is in the charged state at time k-1. The process proceeds to step S105.

  Step S103: After step S101 or when it is determined in step S102 that the first secondary battery 13 is in the discharge continuation state (step S102-Yes), the evaluation parameter calculation unit 27 calculates the evaluation parameter P (k). Are input to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively. In the present embodiment, as shown in the above equation (5), the change amount (decrease amount) of SOC3 from the discharge start time n to time k−1 is determined as the evaluation parameter P (k).

  Step S104: Next, the first coefficient determination unit 28 and the second coefficient determination unit 29 respectively determine the first weighting coefficient α and the second weighting coefficient β corresponding to the evaluation parameter P (k) in step S103. Then, the process proceeds to step S107.

  Step S105: On the other hand, when the first secondary battery 13 is determined to be in the charged state in Step S102 (Step S102-No), the evaluation parameter calculating unit 27 confirms that the first secondary battery 13 is in the charged state. Information to be shown is input to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  Step S106: Next, when the first coefficient determination unit 28 and the second coefficient determination unit 29 acquire information indicating that the first secondary battery 13 is in the charged state in step S105, the first coefficient determination unit 28 and the second coefficient determination unit 29 respectively set the predetermined value C1. The first weighting factor α is set, and the predetermined value C2 is set as the second weighting factor β. For example, the first weighting coefficient α = 0 and the second weighting coefficient β = 1 are set.

  Step S107: After step S104 or after step S106, the adder 32 adds the weighted first charging rate αSOC1 (k) and the weighted second charging rate as shown in the above-described equation (6). The sum of βSOC2 (k) is determined as the third charging rate SOC3 (k).

  Step S108: The charging rate calculation unit 25 increments the time k and returns to step S100.

  Next, with reference to FIG. 7, the experimental value of the charging rate SOC (third charging rate SOC3) estimated by the charging rate calculation device 14 according to the present embodiment will be described.

  FIG. 7A is a diagram in which the horizontal axis represents time k and the vertical axis represents the terminal voltage value v. As described above, in the present embodiment, the time period during which charging / discharging of the first secondary battery 13 is switched in a relatively short time due to regeneration performed when the vehicle is decelerated, for example, while the engine drive is stopped (idling) During which the first secondary battery 13 continues to discharge. The terminal voltage value fluctuates in a relatively short time in a time zone (region A in the figure) in which charging / discharging is switched in a short time. On the other hand, the terminal voltage value decreases at a substantially constant rate of time change in the time period in which discharge continues (region B in the figure).

  FIG. 7B is a diagram in which the horizontal axis represents time k and the vertical axis represents the charging rate SOC (true value). The horizontal axis corresponds to FIG. The charging rate SOC varies in a relatively short time because charging / discharging is repeatedly performed in the region A in the figure. On the other hand, the charging rate SOC decreases at a substantially constant rate of time change in region B in the figure because discharging continues. This is due to the fact that the power consumption of the load 16 is substantially constant while the engine of the vehicle is stopped (when idling is stopped).

  FIG. 7C is a diagram in which the horizontal axis represents time k and the vertical axis represents the estimation error of the charging rate SOC. For the sake of comparison, the broken line in the figure indicates the case where the first weighting factor α = 1 and the second weighting factor β = 0 in the charging rate calculation device 14, that is, when only the current integration method is used. Indicates the estimation error. Moreover, the solid line in a figure shows the estimation error by the charging rate calculation apparatus 14 which concerns on this Embodiment. As is apparent from FIG. 7C, according to the charging rate calculation device 14 according to the present embodiment, the estimation error is reduced particularly in the region B, that is, the time zone in which the discharge continues. Further, according to the charging rate calculation device 14 according to the present embodiment, the estimation error is reduced in the region A, that is, in the time zone in which charging / discharging is switched in a relatively short time, in the relatively short time zone in which the discharging is performed. Has been.

  As described above, according to the charging rate calculation device 14 according to Embodiment 1 of the present invention, the first charging rate SOC1 and the open-circuit voltage by the current integration method according to the discharge duration of the first secondary battery 13. Weighting is performed on each of the second charging rates SOC2 by the estimation method. For this reason, for example, when the discharge of the first secondary battery 13 continues, the estimation error of the third charging rate SOC3 is reduced, so that the estimation accuracy of the third charging rate SOC3 is improved.

  Preferably, the charging rate calculation device 14 increases the first weighting factor α with respect to the first charging rate SOC1 and increases the second charging rate SOC2 as the discharge duration of the first secondary battery 13 increases. The second weight coefficient β for is reduced. In this way, as the discharge of the first secondary battery 13 continues, the contribution of the open-circuit voltage estimation method that decreases the charging rate estimation accuracy is reduced, and the estimation accuracy of the third charging rate SOC3 is further improved. .

  Preferably, the charging rate calculation device 14 sets the first weighting coefficient α and the second weighting coefficient β to predetermined values C1 and C2, respectively, when the first secondary battery 13 is in a charged state. For this reason, when the estimation accuracy of the charging rate by the open-circuit voltage estimation method is relatively high, such as when the first secondary battery 13 is in a charged state, it corresponds to the discharge duration of the first secondary battery 13 described above Since the weighting is stopped, the estimation accuracy of the third charging rate SOC3 is further improved.

  In addition, preferably, the charging rate calculation device 14 sets a time when the decrease of the third charging rate SOC3 starts as a discharge start time n which is a start time of the discharge continuation state. As described above, in the time zone in which the discharge of the first secondary battery 13 continues, the true value of the charging rate decreases at a substantially constant rate of time change (for example, see region B in FIG. 7B). For this reason, the charging rate calculation apparatus 14 can determine the start of discharge of the first secondary battery 13 with high accuracy by determining a decrease in the third charging rate SOC3.

  Also preferably, the charging rate calculation device 14 has a first weighting factor α and a second weighting factor β in accordance with the amount of change in the evaluation parameter P, in this embodiment the amount of decrease in the third charging rate SOC3. To decide. Here, the charging rate according to the open-circuit voltage estimation method is likely to be reduced in accuracy when discharging is performed with a large current, compared to when discharging is performed with a small current in a certain discharge duration. Here, the amount of decrease in the third charging rate SOC3 increases as the discharge current increases during a certain discharge duration. For this reason, according to the charging rate calculation device 14 according to the present embodiment, for example, a lookup table that indicates the correspondence between the discharge duration and the coefficient is used as the first lookup table and the second lookup table. Since the coefficient is determined in consideration of the change in the charging rate, that is, the magnitude of the discharge current, the estimation accuracy of the third charging rate SOC3 is further improved.

(Embodiment 2)
Next, the configuration of the charging rate calculation device 14 according to Embodiment 2 of the present invention will be described with reference to FIG. The schematic configuration of storage battery system 10 according to the present embodiment is the same as that of the first embodiment. As an outline, the charging rate calculation device 14 according to the present embodiment is based on the terminal voltage value of the first secondary battery 13 instead of the configuration in which the evaluation parameter P is determined based on the third charging rate SOC3. The difference from the first embodiment is that a configuration for determining the evaluation parameter P is employed. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 8, the charging rate calculation device 14 includes a charging / discharging current detection unit 21, a terminal voltage detection unit 220, a current integration method estimation unit 23, an open-circuit voltage method estimation unit 24, and a charge rate calculation unit 250. And a delay element 26. The charge / discharge current detection unit 21, the current integration method estimation unit 23, the open-circuit voltage method estimation unit 24, and the delay element 26 are the same as those in the first embodiment.

  The terminal voltage detection unit 220 detects the terminal voltage value v (k) of the first secondary battery 13 as in the first embodiment. In the present embodiment, the detected terminal voltage value v (k) is input as an input signal to the current integration method estimation unit 23, the open circuit voltage method estimation unit 24, and the charge rate calculation unit 250, respectively.

  Similarly to the first embodiment, the charging rate calculator 250 uses the first charging rate αSOC1 (k) and the second charging rate that are weighted using the first weighting factor α and the second weighting factor β, respectively. Based on βSOC2 (k), a third charging rate SOC3 (k) is calculated.

  Next, details of the charging rate calculation unit 250 will be described with reference to FIG. 9. The charging rate calculation unit 250 includes an evaluation parameter calculation unit 270, a first coefficient determination unit 28, a second coefficient determination unit 29, a first multiplier 30, a second multiplier 31, and an adder. 32. The first coefficient determination unit 28, the second coefficient determination unit 29, the first multiplier 30, the second multiplier 31, and the adder 32 are the same as those in the first embodiment.

  The evaluation parameter calculation unit 270 calculates the evaluation parameter P (k) according to the discharge duration time of the first secondary battery 13. In the present embodiment, the evaluation parameter P (k) is different from that in the first embodiment. This will be specifically described below.

  First, the evaluation parameter calculation unit 270 accumulates the terminal voltage value v input from the terminal voltage detection unit 220. For example, at time k, the evaluation parameter calculation unit 270 stores terminal voltage values v (k), v (k−1),.

Subsequently, the evaluation parameter calculation unit 270 determines whether or not the discharge of the first secondary battery 13 is started based on the change in the terminal voltage value v. Here, for example, as shown in FIG. 7A, the terminal voltage value decreases at a substantially constant rate of time change in the time period (region B in the figure) in which the discharge of the first secondary battery 13 continues. . For this reason, when the terminal voltage value v increases at a certain time (for example, k = 10) and the terminal voltage value v decreases at the next time (for example, k = 11), the first voltage at time k = 11. It can be determined that the secondary battery 13 has started to discharge. In the present embodiment, evaluation parameter calculation unit 270 determines whether or not Expression (7) and Expression (8) are satisfied at time k.
v (k-2) <v (k-1) (7)
v (k-1)> v (k) (8)

  When Expression (7) and Expression (8) are satisfied, the evaluation parameter calculation unit 270 determines that the discharge of the first secondary battery 13 has started at time k. When the evaluation parameter calculation unit 270 determines that the discharge of the first secondary battery 13 is started, the evaluation parameter calculation unit 270 determines the time k as the discharge start time (start time of discharge duration) n of the first secondary battery 13.

On the other hand, when at least one of Expression (7) and Expression (8) is not satisfied, the evaluation parameter calculation unit 270 determines whether the first secondary battery 13 is in the discharge continuation state based on the change in the terminal voltage value v. Determine whether or not. Here, when the terminal voltage value v decreases at a certain time (for example, k = 10) and the terminal voltage value v also decreases at the next time (for example, k = 11), the terminal voltage value v is decreased at time k = 11. It can be determined that the discharge of one secondary battery 13 is continuing. In the present embodiment, evaluation parameter calculation section 270 determines whether or not expressions (9) and (10) are satisfied at time k.
v (k-2)> v (k-1) (9)
v (k-1)> v (k) (10)

  When Expression (9) and Expression (10) are satisfied, the evaluation parameter calculation unit 270 determines that the first secondary battery 13 is in the discharge continuation state at time k.

Here, if it is determined that the first secondary battery 13 is in the discharge start state or the discharge continuation state at the time k, the evaluation parameter calculation unit 270 is a terminal from the discharge start time n to the time k as shown in Expression (11). The change amount (decrease amount) of the voltage value v is determined as the evaluation parameter P (k).
P (k) = v (n) −v (k) (11)

  As shown in the equation (11), the evaluation parameter P (k) according to the present embodiment is the discharge duration of the first secondary battery 13 (k in the equation (11) is the same as in the first embodiment. -N). Specifically, as the discharge duration increases, the value of the evaluation parameter P (k) increases.

  Then, after calculating the evaluation parameter P (k), the evaluation parameter calculation unit 270 inputs the evaluation parameter P (k) to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  On the other hand, when at least one of Expression (9) and Expression (10) is not satisfied, evaluation parameter calculation unit 270 determines that first secondary battery 13 is in the charged state at time k. Then, the evaluation parameter calculation unit 270 inputs information indicating that the first secondary battery 13 is in a charged state to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  As described above, according to the charging rate calculation device 14 according to Embodiment 2 of the present invention, the first charging rate SOC1 and the open circuit voltage by the current integration method according to the discharge duration of the first secondary battery 13. Weighting is performed on each of the second charging rates SOC2 by the estimation method. For this reason, as in the first embodiment, the estimation accuracy of the third charging rate SOC3 is improved.

  Preferably, the charging rate calculation device 14 sets the time when the terminal voltage value v of the first secondary battery 13 starts to decrease to the discharge start time n that is the start time of the discharge continuation state. As described above, the terminal voltage of the first secondary battery 13 decreases at a substantially constant rate of time change during the time period in which the discharge of the first secondary battery 13 continues (for example, as shown in FIG. 7A). Area B). For this reason, the charging rate calculation device 14 can determine the start of discharge of the first secondary battery 13 with high accuracy by determining the decrease in the terminal voltage value v of the first secondary battery 13.

  Also preferably, the charging rate calculation device 14 uses the first weighting coefficient α and the first weighting factor α according to the amount of change in the evaluation parameter P, in this embodiment, the amount of decrease in the terminal voltage value v of the first secondary battery 13. A second weighting factor β is determined. Here, the charging rate according to the open-circuit voltage estimation method is likely to be reduced in accuracy when discharging is performed with a large current, compared to when discharging is performed with a small current in a certain discharge duration. Here, the amount of decrease in the terminal voltage value v increases as the discharge current increases during a certain discharge duration. For this reason, according to the charging rate calculation device 14 according to the present embodiment, for example, a lookup table that indicates the correspondence between the discharge duration and the coefficient is used as the first lookup table and the second lookup table. Compared with the above, since the coefficient is determined in consideration of the change in the terminal voltage value v of the first secondary battery 13, that is, the magnitude of the discharge current, the estimation accuracy of the third charging rate SOC3 is further improved. .

(Embodiment 3)
Next, the configuration of the charging rate calculation device 14 according to Embodiment 3 of the present invention will be described. The schematic configuration of the storage battery system 10 and the charging rate calculation device 14 according to the present embodiment is the same as that of the first embodiment. As an outline, the charging rate calculation device 14 according to the present embodiment replaces the configuration in which the evaluation parameter P is determined based on the third charging rate SOC3 with the first second determined based on the power generation state of the alternator 11. The difference from the first embodiment is that a configuration in which the discharge duration of the secondary battery 13 is set as the evaluation parameter P is adopted. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 10, the charging rate calculation device 14 includes a charging / discharging current detection unit 21, a terminal voltage detection unit 22, a current integration method estimation unit 23, an open-circuit voltage method estimation unit 24, and a charge rate calculation unit 251. And a delay element 26. The charge / discharge current detection unit 21, the terminal voltage detection unit 22, the current integration method estimation unit 23, the open-circuit voltage method estimation unit 24, and the delay element 26 are the same as those in the first embodiment.

  Similarly to the first embodiment, the charging rate calculation unit 251 performs the first charging rate αSOC1 (k) and the second charging rate that are weighted using the first weighting factor α and the second weighting factor β, respectively. Based on βSOC2 (k), a third charging rate SOC3 (k) is calculated.

  Next, details of the charging rate calculation unit 251 will be described with reference to FIG. The charging rate calculation unit 251 includes a communication unit 331, an evaluation parameter calculation unit 271, a first coefficient determination unit 28, a second coefficient determination unit 29, a first multiplier 30, and a second multiplier. 31 and an adder 32. The first coefficient determination unit 28, the second coefficient determination unit 29, the first multiplier 30, the second multiplier 31, and the adder 32 are the same as those in the first embodiment.

  The communication unit 331 is an interface that transmits and receives information via an in-vehicle network such as a CAN provided in the vehicle. The communication unit 331 acquires control information of the alternator 11 from the in-vehicle network. The control information of the alternator 11 includes information indicating the power generation state of the alternator 11, for example, the start of power generation and the stop of power generation. For example, the control information of the alternator 11 includes a regulator voltage command value for adjusting the output voltage of the alternator 11. According to the regulator voltage command value of the alternator 11, the power generation state of the alternator 11, for example, the start of power generation and the stop of power generation can be detected.

  The evaluation parameter calculation unit 271 calculates the evaluation parameter P (k) according to the discharge duration time of the first secondary battery 13. In the present embodiment, the evaluation parameter P (k) is different from that in the first embodiment. This will be specifically described below.

  First, the evaluation parameter calculation unit 271 detects the stop of power generation of the alternator 11 based on the control information of the alternator 11 received by the communication unit 331. Here, when the power generation of the alternator 11 is stopped, the power supply (discharge) by the first secondary battery 13 is started as described above.

  Subsequently, when the evaluation parameter calculation unit 271 detects the stop of the power generation of the alternator 11, the time k at which the stop of the power generation is detected is set to the discharge start time (start time of the discharge duration) n of the first secondary battery 13. Determine.

Subsequently, until the power generation of the alternator 11 is started based on the control information of the alternator 11 acquired by the communication unit 331, the evaluation parameter calculation unit 271 is from the discharge start time n to the time k as shown in Expression (12). Is determined as an evaluation parameter P (k).
P (k) = kn (12)

  As shown in Expression (12), the evaluation parameter P (k) according to the present embodiment is the discharge duration kn itself of the first secondary battery 13. Therefore, the value of the evaluation parameter P (k) increases as the discharge duration increases.

  Then, after calculating the evaluation parameter P (k), the evaluation parameter calculation unit 271 inputs the evaluation parameter P (k) to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  On the other hand, when the evaluation parameter calculation unit 271 detects the start of power generation of the alternator 11 based on the control information of the alternator 11 acquired by the communication unit 331, the first secondary battery 13 at time k when the start of power generation of the alternator 11 is detected. Is determined to be in a charged state. Then, the evaluation parameter calculation unit 271 inputs information indicating that the first secondary battery 13 is in a charged state to the first coefficient determination unit 28 and the second coefficient determination unit 29, respectively.

  As described above, according to the charging rate calculation device 14 according to Embodiment 3 of the present invention, the first charging rate SOC1 and the open-circuit voltage by the current integration method according to the discharge duration of the first secondary battery 13. Weighting is performed on each of the second charging rates SOC2 by the estimation method. For this reason, as in the first embodiment, the estimation accuracy of the third charging rate SOC3 is improved.

  Further, when the charging rate calculation device 14 detects the power generation stop of the alternator 11 based on the control information of the alternator 11, the charging rate calculation device 14 sets the time k at which the power generation stop of the alternator 11 is detected as the starting time n of the discharge duration time. Thus, since the power generation stop time of the alternator 11 that can be detected based on the control information of the alternator 11 can be regarded as the discharge start time n of the first secondary battery 13, The start of discharge can be determined with high accuracy.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

  For example, in the above-described third embodiment, the configuration in which the charging rate calculation device 14 determines the power generation stop time of the alternator 11 as the discharge start time of the first secondary battery 13 based on the control information of the alternator 11 has been described. However, the discharge start time of the first secondary battery 13 may be determined based on other information. For example, the charge rate calculation unit 251 of the charge rate calculation device 14 uses the engine stop time detected by the communication unit 331 based on the engine control information received from the in-vehicle network as the discharge start time of the first secondary battery 13. You may decide to.

  Moreover, in embodiment mentioned above, although the storage battery system 10 mounted in a hybrid vehicle was demonstrated, it is not restricted to this. For example, the storage battery system 10 may be mounted on an electric vehicle (EV vehicle).

  Moreover, in embodiment mentioned above, although the storage battery system 10 demonstrated the structure provided with the 2nd secondary battery 15 which is the 1st secondary battery 13 and a lead storage battery, such as a lithium ion battery, it is not restricted to this. . For example, the storage battery system 10 may further include another secondary battery having a battery capacity different from that of the first secondary battery 13 or the second secondary battery 15.

DESCRIPTION OF SYMBOLS 10 Storage battery system 11 Alternator 12 Starter 13 1st secondary battery 14 Charge rate calculation apparatus 15 2nd secondary battery 16 Load 17 1st switch 18 2nd switch 19 3rd switch 20 Control part 21 Charging / discharging current Detection unit 22, 220 Terminal voltage detection unit 23 Current integration method estimation unit 24 Open-circuit voltage method estimation unit 25, 250, 251 Charging rate calculation unit 26 Delay element 27, 270, 271 Evaluation parameter calculation unit 28 First coefficient determination unit 29 Second coefficient determination unit 30 First multiplier 31 Second multiplier 32 Adder 331 Communication unit

Claims (6)

A charge / discharge current detector for detecting a charge / discharge current value of the secondary battery;
A terminal voltage detector for detecting a terminal voltage value of the secondary battery;
A first estimation unit that accumulates the charge / discharge current values and estimates a first charging rate;
A second estimation unit that estimates a second charging rate based on a relationship between an open-circuit voltage value of the secondary battery and a charging rate;
A charge rate calculation unit for calculating a third charge rate based on the first charge rate and the second charge rate each weighted according to the discharge duration of the secondary battery;
A charging rate calculation device for a secondary battery. The charging rate calculation device according to claim 1,
The charging rate calculation unit is configured to increase the weighting for the first charging rate and decrease the weighting for the second charging rate as the discharge duration of the secondary battery increases. It is a charge rate calculation device according to claim 1 or 2,
The charging rate calculation unit is a charging rate calculation device that sets the weighting for the first charging rate and the weighting for the second charging rate to predetermined values, respectively, when the secondary battery is in a charged state. It is a charge rate calculation device according to any one of claims 1 to 3,
The charging rate calculation unit is a charging rate calculation device that determines a time at which a decrease in the terminal voltage value of the third charging rate or the secondary battery starts as a starting time of the discharge duration time. The charging rate calculation device according to claim 4,
The charging rate calculation unit weights the first charging rate according to a decrease amount of the third charging rate or a decrease amount of the terminal voltage value of the secondary battery from the calculation time and the second charging rate. The charge rate calculation apparatus which performs weighting with respect to the charge rate. It is a charge rate calculation device according to any one of claims 1 to 3,
Via a vehicle-mounted network of a vehicle equipped with an alternator for charging the secondary battery, further comprising a communication unit for obtaining control information of the alternator;
The charging rate calculation unit
The charging rate calculation apparatus which determines the time when the power generation of the alternator stopped as the starting time of the discharge duration time.

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