JP7103809B2 - Battery control device - Google Patents

Description

The present invention relates to a battery control device.

A battery control device mounted on an electric vehicle (EV), a plug-in hybrid vehicle, a hybrid vehicle, or the like is electrically connected between a secondary battery and a load such as a motor. When the battery control device detects excessive use of the secondary battery, the battery control device limits the power applied to the load of the motor or the like from the secondary battery in order to suppress a decrease in output due to deterioration of the secondary battery.

Patent Document 1 describes a technique for limiting charge / discharge when the ratio of the time when the effective current value exceeds the permissible value within a specified time is higher than a predetermined threshold value.

International release WO2015 / 019875

The degree of deterioration of the secondary battery varies depending on the actual usage conditions of the vehicle and the like. Compared with the technique described in Patent Document 1, it is required to more accurately reflect the usage state of the secondary battery and determine the power to be limited.

The battery control device according to the present invention is a battery control device that is connected to a secondary battery and controls charging / discharging of the secondary battery, and is based on the frequency of charging and discharging of the secondary battery in a predetermined period. A charge / discharge frequency calculation unit that obtains the load characteristic amount of the load applied to the secondary battery, and a power limit value calculation unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the load characteristic amount. To be equipped.

According to the present invention, since the input / output power of the secondary battery is limited based on the load feature amount, the power to be limited is determined by more accurately reflecting the usage state of the secondary battery. Can be done.

It is a block diagram of a battery system. It is a figure which shows the circuit structure of the cell cell control part. It is a block block diagram of a battery control part. (A) (b) It is a figure which shows the current flowing through a secondary battery, and the energization time number table. It is a block block diagram of the power limit rate calculation part. It is a graph which shows the relationship between a load judgment index (%) and a power limit rate. It is a figure which shows an example of (a) (b) limit threshold map. (A) (b) is a graph showing current waveforms having different continuous energization times. (A) (b) It is a graph which shows the deterioration behavior when the current waveforms with different continuous energization times are input. It is a flowchart which shows the operation of the battery control part. (A) and (b) are graphs showing battery power and SOHR when this embodiment is not applied, respectively. (A), (b), and (c) are graphs showing battery power, load determination index, and SOHR when this embodiment is applied. It is a figure which shows an example of (a) (b) limit threshold map. It is a block block diagram of the power limit rate calculation part in 2nd Embodiment. It is a figure which shows the limit start end threshold table in 2nd Embodiment. (A) (b) is a power limit rate map in which the load determination index and the power limit rate in the second embodiment are associated with each other. It is a flowchart which shows the operation of the battery control part in 2nd Embodiment. (A), (b), and (c) are graphs showing the battery power, the load determination index, and the SOHR when the second embodiment is applied. It is a figure which shows the current flowing through the secondary battery and the sampling point in 3rd Embodiment. It is a figure which shows the relationship between the power spectrum and the frequency in 3rd Embodiment. (A) and (b) are diagrams showing an example of a limit threshold map according to the third embodiment. It is a flowchart which shows the operation of the battery control part in 3rd Embodiment.

In the embodiment described below, an example in which the battery control device according to the present invention is applied to a plug-in hybrid vehicle (PHEV) will be described. In addition, the present invention can be applied to passenger cars such as hybrid vehicles (HEV) and electric vehicles (EV) and industrial vehicles such as hybrid railroad vehicles. Further, in the configuration of the embodiment described below, a case where a lithium ion battery is applied as the secondary battery will be described as an example. As the secondary battery, a nickel hydrogen battery, a lead battery, an electric double layer capacitor, a hybrid capacitor and the like may also be used.

[First Embodiment]
The first embodiment will be described with reference to FIGS. 1 to 13.
FIG. 1 is a configuration diagram of a battery system 100 of a hybrid vehicle.
The battery system 100 includes an assembled battery 110 composed of a plurality of single batteries 111, a single battery management unit 120 that monitors the state of the single battery 111, and a current detection unit 130 that detects the current flowing through the assembled battery 110. A voltage detection unit 140 that detects the total voltage of the battery 110, a battery control unit 150 that controls the assembled battery 110, and a storage unit 180 that stores information on the battery characteristics of the assembled battery 110, the cell 111, and the cell group 112. It is composed of and.

The battery control unit 150 includes the battery voltage and temperature of the cell 111 transmitted from the cell management unit 120 via an insulating element 170 such as a photocoupler, and the current flowing through the battery system 100 transmitted from the current detection unit 130. The value and the total voltage value of the assembled battery 110 transmitted from the voltage detection unit 140 are input. The battery control unit 150 detects the state of the assembled battery 110 based on the input information, and calculates the power limit value and the like. Further, the calculation result performed by the battery control unit 150 is transmitted to the cell management unit 120 and the vehicle control unit 200.

The assembled battery (secondary battery) 110 is configured by electrically connecting a plurality of single batteries 111 (lithium ion batteries) capable of storing and discharging electric energy (charging / discharging DC power) in series. The case where the output voltage of one cell 111 is 3.0 to 4.2 V (average output voltage: 3.6 V) will be described as an example, but other voltage specifications may be used. ..

The unit cells 111 constituting the assembled battery 110 are grouped into a predetermined number of units in order to manage and control the battery state. The grouped cell cells 111 are electrically connected in series to form the cell group 112a and 112b. The number of each cell 111 of the cell groups 112a and 112b may be grouped into the same number, for example, 1, 4, 6, ..., 4 and 6 respectively. They may be combined and grouped into different numbers. In the present embodiment, for the sake of simplicity, the assembled battery 110 electrically connects four cell batteries 111 in series to form the cell group 112a and 112b, and further electrically connects them in series. It was connected and provided with a total of eight cell batteries 111.

The cell management unit 120 that monitors the state of the cell 111 that constitutes the assembled battery 110 is composed of a plurality of cell control units 121a and 121b, and controls the cell group 112a that is grouped. The unit 121a is assigned the cell control unit 121b to the cell group 112b. The cell control units 121a and 121b operate by receiving electric power from the assigned cell groups 112a and 112b, and monitor and control the state of the cell cells 111 constituting the cell groups 112a and 112b.

FIG. 2 is a diagram showing a circuit configuration of the cell control unit 121a. Since the cell control unit 121b also has the same circuit configuration, the description thereof will be omitted.
The cell control unit 121a includes a voltage detection circuit 122, a control circuit 123, a signal input / output circuit 124, and a temperature detection unit 125. The voltage detection circuit 122 measures the voltage between the terminals of each cell 111. The temperature detection unit 125 measures the temperature of the cell group 112a. The control circuit 123 receives the measurement results from the voltage detection circuit 122 and the temperature detection unit 125 and transmits them to the battery control unit 150 via the signal input / output circuit 124. Since the circuit for equalizing the voltage variation between the cell cells 111 generated due to self-discharge, the variation in current consumption, etc. is a general circuit mounted on the cell cell control unit 121a, the description thereof will be omitted.

The temperature detection unit 125 included in the cell control unit 121a in FIG. 2 has a function of measuring the temperature of the cell group 112a. The temperature detection unit 125 measures one temperature of the cell group 112a as a whole, and handles the temperature as a representative temperature value of the cell 111 constituting the cell group 112a. The temperature measured by the temperature detection unit 125 is used for various calculations for detecting the state of the cell 111, the cell group 112a, or the assembled battery 110. A temperature detection unit 125 may be provided for each cell 111 to measure the temperature of each cell 111, and various calculations may be executed based on the temperature of each cell 111. In this case, as the number of temperature detection units 125 increases, the configuration of the cell control unit 121 becomes complicated.

In FIG. 2, the temperature detection unit 125 is simply illustrated, but more specifically, a temperature sensor is installed in the temperature measurement target, and the installed temperature sensor outputs temperature information as a voltage. The output measurement result is transmitted to the signal input / output circuit 124 via the control circuit 123, and the signal input / output circuit 124 outputs the measurement result to the outside of the cell control unit 121a. A function for realizing this series of flows is mounted on the cell control unit 121 as a temperature detection unit 125, and a voltage detection circuit 122 can also be used for measuring temperature information (voltage).

Returning to the description of FIG. 1, the battery control unit 150 outputs the measured values of the battery voltage and temperature of the cell 111 output from the cell management unit 120, the current value from the current detection unit 130, and the voltage detection unit 140. The total voltage value of the assembled battery 110 and the battery characteristic information of the cell 111 stored in the storage unit 180 are input. Further, the cell management unit 120 has a function of diagnosing whether the cell 111 is overcharged or overdischarged, and a function of outputting an abnormal signal when a communication error or the like occurs in the cell management unit 120. The diagnosis results and abnormal signals are also input to the battery control unit 150. Further, a signal from the vehicle control unit 200, which is a higher-level control device, is also input to the battery control unit 150.

The battery control unit 150 limits the charge and discharge of the assembled battery 110 appropriately based on the input information, the current limit value stored in advance in the storage unit 180, and the battery characteristics of the cell 111. Calculation of the value, calculation of the state of charge (SOC: State Of Charge) and deterioration state (SOHR: State Of Health based on Resistance) of the cell 111, and the like are executed. The battery control unit 150 outputs these calculation results and commands based on the calculation results to the cell management unit 120 and the vehicle control unit 200.

The storage unit 180 stores information on the limit value of the battery system 100 and the battery characteristics of the assembled battery 110, the cell 111, and the cell groups 112a and 112b. In the present embodiment, the storage unit 180 is configured to be installed outside the battery control unit 150 or the cell management unit 120, but the battery control unit 150 or the cell management unit 120 is configured to include the storage unit. , The above-mentioned information may be stored in this storage unit.

The battery control unit 150 and the cell management unit 120 transmit and receive signals by the signal line 160 via an insulating element 170 such as a photocoupler. The reason why the insulating element 170 is provided is that the operating power sources are different between the battery control unit 150 and the cell management unit 120. That is, the cell management unit 120 operates by receiving electric power from the assembled battery 110, whereas the battery control unit 150 uses a battery for an in-vehicle auxiliary machine (for example, a 14V system battery) as a power source. The insulating element 170 may be mounted on the circuit board that constitutes the cell management unit 120, or may be mounted on the circuit board that constitutes the battery control unit 150. Depending on the system configuration, the insulating element 170 may be omitted.

The communication between the battery control unit 150 and the cell control units 121a and 121b in the present embodiment will be described. The cell control units 121a and 121b are connected in series in descending order of potential of the cell groups 112a and 112b monitored by each. The signal transmitted by the battery control unit 150 is input to the cell control unit 121a by the signal line 160 via the insulating element 170. Similarly, the output of the cell control unit 121a and the input of the cell control unit 121b are also connected by a signal line 160 to transmit a signal. In the present embodiment, the connection between the cell control unit 121a and the cell control unit 121b is not via the insulating element 170, but may be via the insulating element 170. Then, the output of the cell control unit 121b is transmitted to the battery control unit 150 via the insulating element 170 and the signal line 160. In this way, the battery control unit 150 and the cell control units 121a and 121b are connected in a loop by the signal line 160. This loop connection is sometimes referred to as a daisy chain connection, a beaded connection, or a potato-type connection.

The vehicle control unit 200 controls the inverter 400 connected to the battery system 100 via the relays 300 and 310 based on the information of the battery control unit 150. The battery system 100 is connected to the inverter 400 and drives the motor generator 410 based on the energy stored in the assembled battery 110. When the vehicle control unit 200 receives information indicating the power limit value from the battery control unit 150, the vehicle control unit 200 controls the inverter 400 and drives the motor generator 410 so as not to exceed the power limit value. The power limit value output by the battery control unit 150 will be described later.

FIG. 3 is a block configuration diagram of the battery control unit 150.
The battery control unit 150 includes a battery state detection unit 151, an input / output possible power calculation unit 152, a charge / discharge frequency calculation unit 153, a power limit rate calculation unit 154, and a power limit rate reflection unit 155.

The battery state detection unit 151 calculates and outputs the SOC and SOHR of the assembled battery 110 based on the information of the current flowing through the assembled battery 110, the voltage of the assembled battery 110, and the temperature of the assembled battery 110.

The input / output possible power calculation unit 152 calculates and outputs the input / output possible power based on the temperatures of the SOC, SOHR, and the assembled battery 110. Since the calculation methods of SOC, SOHR, and input / output possible power are well known, the description thereof will be omitted.

The charge / discharge frequency calculation unit 153 measures the energization time in which the current flows continuously based on the current flowing in the assembled battery 110, and outputs an energization time frequency table that stores the frequency (number of times) for each energization time. .. The output energization time count table is written in the storage unit 180, read out at the next vehicle startup, extracts the most frequent energization time from the energization time count table as the load feature amount, and power limit rate calculation unit. Output to 154.

The power limit rate calculation unit 154 calculates the power limit rate based on the load feature amount, voltage, temperature, and SOC, and outputs the power limit rate to the power limit rate reflection unit 155. The power limit rate reflection unit 155 calculates the power limit value based on the input / output possible power and the power limit rate. The power limit rate and the power limit value will be described later.

FIG. 4A is a diagram showing a current flowing through a secondary battery which is an assembled battery 110, and FIG. 4B is a diagram showing a table of the number of times of energization time. With reference to these figures, the energization time number table by the charge / discharge frequency calculation unit 153 will be described.

The horizontal axis of FIG. 4A is time, and the vertical axis shows an example of the current flowing through the secondary battery. In FIG. 4A, the current is indicated by a thick line, and the current effective determination threshold value is indicated by a alternate long and short dash line. The region where the absolute value of the current is larger than the current valid determination threshold is the energization time count effective region. The region where the absolute value of the current is below the current valid determination threshold is the energization time count invalid region. The charge / discharge frequency calculation unit 153 starts measuring the energization time when the absolute value of the current is larger than the current valid determination threshold value, and ends the measurement when it falls below the current valid determination threshold value. Then, the frequency corresponding to the measured energization time is added by +1 to the energization time frequency table shown in FIG. 4 (b).

The energization time shown in FIG. 4B is divided every 3 seconds, and when the absolute value of the current shown in FIG. 4A is larger than the current valid determination threshold value, the energization time is 1 second, and the energization time is shown in FIG. 4 (a). Add +1 to the frequency corresponding to the energization time 0 to 2 in b). When the energization time in which the absolute value of the current shown in FIG. 4 (a) is larger than the current valid determination threshold value is 5 seconds, the frequency corresponding to the energization times 4 to 6 in FIG. 4 (b) is added by +1. When the energization time in which the absolute value of the current shown in FIG. 4 (a) is larger than the current valid determination threshold value is 18 seconds, the frequency corresponding to the energization times 16 to 18 in FIG. 4 (b) is added by +1. In this way, the charge / discharge frequency calculation unit 153 stores the frequency information for each energization time in the energization time frequency table. The energization time frequency table in which the frequency information is accumulated is stored in the storage unit 180 when the vehicle is stopped, and is read from the storage unit 180 when the vehicle is started next time. The most frequent energization time is selected from the read table, and the selected result is output to the power limit rate calculation unit 154 as a load feature amount. After determining the load feature amount, the charge / discharge frequency calculation unit 153 clears the frequency information in the energization time frequency table stored internally, and resumes the accumulation of the frequency information again.

FIG. 5 is a block configuration diagram of the power limit rate calculation unit 154. The power limit rate calculation unit 154 is composed of a threshold map selection unit 154-1, a threshold value calculation unit 154-2, a load determination index calculation unit 154.3, and a limit rate calculation unit 154-2.

The threshold map selection unit 154-1 is determined by the charge / discharge frequency calculation unit 153 from each load feature amount stored in the storage unit 180 in advance, and in this embodiment, a database of limit threshold maps corresponding to the energization time. Select the limit threshold map (FIGS. 7A or 7B) corresponding to the load feature amount. The threshold value calculation unit 154-2 determines the voltage difference limit value corresponding to the temperature of the secondary battery and the predetermined time window Tw based on the selected limit threshold value map of FIG. 7A or FIG. 7B. And output. The limit threshold map and the time window Tw will be described later with reference to FIG. The limit threshold map is a voltage or current limit characteristic.

ここで、ΔV(t)は電圧差(V)である。 The load determination index calculation unit 154-3 calculates and outputs the load determination index based on the voltage difference limit value, the voltage of the secondary battery, and the SOC. Hereinafter, the calculation of the load determination index will be described.
The load determination index calculation unit 154-3 converts the input SOC into an open circuit voltage (OCV), and the difference between the battery voltage (CCV: Closed circuit voltage) and the open circuit voltage (CCV: Closed circuit voltage) according to the following equation (1). Hereinafter, the voltage difference) is obtained.

Here, ΔV (t) is the voltage difference (V).

ここで、ΔV_Fiter(t)はΔV2の一次遅れフィルタ適用結果(V2)、t_sは制御周期(sec)、Twは時間窓(sec)である。 Next, as an index for determining the past usage history of the secondary battery, the result of applying the first-order lag filter to the square of ΔV (t) in the equation (1) is calculated based on the following equation (2).

Here, ΔV _Fiter (t) is the result of applying the first-order lag filter of ΔV2 (V2), t _s is the control period (sec), and Tw is the time window (sec).

ここで、ΔV_RMS(t)は実効電圧差(V)である。そして、次式（４）で負荷判定指標(%)を求める。

ここで、ΔV_Thresh(t)は制限閾値(V)、ΔV_Ratio(t)は負荷判定指標(%)である。 Further, the units of the voltage are aligned by the equation (3).

Here, ΔV _RMS (t) is the effective voltage difference (V). Then, the load determination index (%) is obtained by the following equation (4).

Here, ΔV _Thresh (t) is the limiting threshold value (V), and ΔV _Ratio (t) is the load determination index (%).

Next, the limit rate calculation unit 154-4 will be described with reference to FIG. FIG. 6 is a graph showing the relationship between the load determination index (%) and the power limit rate. The horizontal axis of FIG. 6 shows the load determination index, and the vertical axis shows the power limit rate. When the load determination index exceeds Th1, the power limit rate decreases from 1, and becomes 0 when Th2 is reached. The limit rate calculation unit 154-4 calculates the power limit rate with reference to the graph shown in FIG. 6 based on the load determination index output from the load determination index calculation unit 154-3.

ここで、k(t)は電力制限率、Pchg_nolimit(t)は充電側の入出力可能電力、Pchg(t)は充電側の電力制限値である。

ここで、k(t)は電力制限率、Pdis_nolimit(t)は放電側の入出力可能電力、Pdis(t)は放電側の電力制限値である。 Returning to FIG. 3, the power limit rate reflecting unit 155 will be described. In the power limit rate reflection unit 155, the power limit rate calculated by the power limit rate calculation unit 154 and the input / output possible power calculated by the input / output possible power calculation unit 152 are based on the following equations (5) and (6). Calculate the power limit value.

Here, k (t) is the power limit rate, Pchg_nolimit (t) is the input / output possible power on the charging side, and Pchg (t) is the power limit value on the charging side.

Here, k (t) is the power limit rate, Pdis_nolimit (t) is the input / output possible power on the discharge side, and Pdis (t) is the power limit value on the discharge side.

7 (a) and 7 (b) are diagrams showing an example of a limit threshold map. The limit threshold map is stored in the storage unit 180 according to the load feature amount and the energization time in the present embodiment. The horizontal axis of FIGS. 7 (a) and 7 (b) represents the time window, and the vertical axis represents the voltage difference limit value. The time window is the time constant of the first-order lag filter, which is a predetermined constant.

FIG. 7A is a limit threshold map corresponding to the case where the frequency of continuous energization for a short time is high. FIG. 7B is a limit threshold map corresponding to a case where the frequency of continuous energization for a long time is high, and the voltage difference limit value is also lower than that of FIG. 7A. Further, the lower the temperature of the secondary battery, the lower the voltage difference limit value. For example, when the calculated load feature amount is continuous energization for a short time, the limit threshold map of FIG. 7A is applied. These limit threshold maps according to the load feature amount are obtained in advance by the charge / discharge test of the secondary battery, and reflect the limit characteristics of the secondary battery. The limit threshold map is not limited to the two shown in FIGS. 7 (a) and 7 (b), and a plurality of limit threshold maps may be provided according to the energization time.

8 (a) and 8 (b) are graphs showing current waveforms having different continuous energization times. In each figure, the horizontal axis represents time and the vertical axis represents current. Further, in each figure, the current is indicated by a thick line, and the current effective determination threshold value is indicated by a long-dotted chain line. FIG. 8A shows the case of charging / discharging in which the frequency of short-time energization is high. FIG. 8B shows the case of charging / discharging in which the frequency of energization for a long time is high.

9 (a) and 9 (b) are graphs showing deterioration behavior when current waveforms having different continuous energization times are input. In each figure, the horizontal axis represents time and the vertical axis represents SOHR. FIG. 9A corresponds to the deterioration behavior when the current waveform of FIG. 8A is repeatedly input, and shows the deterioration behavior during charging / discharging in which the frequency of short-time energization is high. FIG. 9B corresponds to the deterioration behavior when the current waveform of FIG. 8B is repeatedly input, and shows the deterioration behavior during charging / discharging in which the frequency of long-term energization is high. As shown in FIGS. 9A and 9B, even if the mean square value of current or electric power is the same, the deterioration behavior differs depending on the continuous energization time of charging or discharging. Specifically, in the case where the continuous energization time is long, there is a region Q in which the resistance rises sharply at a certain time, and the deterioration tends to progress rapidly. In the present embodiment, in order to suppress the rapid progress of deterioration, a cycle test is carried out using pulse currents having the same root mean square value and different continuous energization times, and a limiting threshold value so that the rapid progress of deterioration does not occur. Set the map.

FIG. 10 is a flowchart showing the operation of the battery control unit 150.
When the vehicle start signal is received in step S101, the process proceeds to the next step S102. In step S102, the charge / discharge frequency calculation unit 153 reads out the frequency information of the energization time until the end of the previous run, that is, the energization time number table from the storage unit 180, and proceeds to the next step S103.

In step S103, the most frequent (number of times) energization time is determined as the load feature amount from the read energization time number table, and the process proceeds to step S104.
In step S104, the determined energization time, that is, the limit threshold map corresponding to the load feature amount is read from the storage unit 180 and selected. Then, the frequency information of the energization time stored in the charge / discharge frequency calculation unit 153, that is, the energization time frequency table is cleared.

In step S105, the power limit rate calculation unit 154 calculates the power limit rate based on the voltage difference limit value, the voltage, the temperature, and the SOC determined based on the selected limit threshold map. Then, the power limit rate reflection unit 155 calculates the power limit value based on the input / output possible power and the power limit rate. The calculated power limit value is output to the vehicle control unit 200. The vehicle control unit 200 drives the inverter 400 to limit the input / output power to the secondary battery so as not to exceed the input power limit value. In addition, the charge / discharge frequency calculation unit 153 newly updates the frequency information of the energization time.

In step S106, it is determined whether or not the vehicle stop signal has been received. Until the vehicle stop signal is received, the operation according to step S105 is continued, and after receiving the vehicle stop signal, the frequency information of the energization time, that is, the energization time number table is stored in the storage unit 180, and the battery control unit 150 operates. To stop.

11 (a) and 11 (b) show the battery power and SOHR when this embodiment is not applied, respectively. In FIG. 11A, Pchg is the power limit value on the charging side, and Pdis is the power limit value on the discharging side. When this embodiment is not applied, the limit threshold map is not changed based on the frequency information when the vehicle is started, and the same limit threshold map is always used. Therefore, as shown in FIG. 11A, it is not possible to execute the power limitation that reflects the charge / discharge history until the vehicle stop signal is received. As a result, even if charging / discharging is performed so that a current with a long energization time is frequently generated before receiving the vehicle stop signal, it is not possible to appropriately limit the charge / discharge according to this, and FIG. 11 (b) shows. As shown in the above, there is a region Q in which the internal resistance sharply increases during charging / discharging due to excessive battery use.

12 (a), (b), and (c) show the battery power, the load determination index, and the SOHR when the present embodiment is applied, respectively. Pchg is the power limit value on the charging side, and Pdis is the power limit value on the discharging side. When the vehicle stop signal is received, the frequency information is stored, and after the vehicle start signal is received, the limit threshold map is set based on the stored frequency information. In the example of FIG. 12, the load determination index calculated based on the limit threshold map of FIG. 7A corresponding to the short energization time is the load determination index calculated based on the limit threshold map corresponding to the long energization time. It is shown assuming the case where it changes to. As a result, as shown in FIG. 12B, the load determination index exceeds the threshold value. As a result, as shown in FIG. 12A, the power is limited and the transient use of the battery is suppressed. Then, as shown in FIG. 12 (c), SOHR is suppressed also in the region Q', and deterioration of the secondary battery is suppressed.

ここで、I(t)：電流(A)、I_Fiter(t)：I2の一次遅れフィルタ適用結果(A2)、t_s：制御周期(sec)、T_w：時間窓(sec)、I_RMS(t)：実効電流(A)、I_Thresh(t)：電流制限値(A)、I_Ratio(t)：電流ベース負荷判定指標(%)である。 In the present embodiment, the load determination index is calculated based on the equations (1) to (4) based on the voltage difference between the battery voltage and the open circuit voltage, but the present embodiment is limited to this. is not. The load determination index may be calculated based on the following equations (7) to (9) using the current in the same manner as when the voltage difference is used.

Here, I (t): current (A), I _Fiter (t): I2 first-order lag filter application result (A2), t _s : control cycle (sec), T _w : time window (sec), I _RMS (t): Effective current (A), I _Thresh (t): Current limit value (A), I _Ratio (t): Current-based load judgment index (%).

13 (a) and 13 (b) are diagrams showing an example of a limit threshold map based on a current limit value. The limit threshold map is stored in the storage unit 180 in association with the load feature amount and the energization time in the present embodiment according to the characteristics of the secondary battery. The horizontal axis of FIGS. 13 (a) and 13 (b) represents the time window, and the vertical axis represents the current limit value. FIG. 13A is a limit threshold map corresponding to the case where the frequency of continuous energization for a short time is high. FIG. 13B is a limit threshold map corresponding to a case where the frequency of continuous energization for a long time is high, and the current limit value is also lower than that of FIG. 13A. Further, the lower the temperature of the secondary battery, the lower the current limit value. For example, when the calculated load feature amount is continuous energization for a short time, the limit threshold map of FIG. 13A is applied. The limit threshold map corresponding to these load features is acquired in advance by a charge / discharge test of the secondary battery.

Even when the power is limited based on the current limit value, the process is performed according to the same procedure as the flowchart shown in FIG. In this case as well, the same effect as in the case of limiting the power based on the voltage difference limit value described above can be obtained.

According to this embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, appropriately suppress the deterioration of the secondary battery, and as a result, protect the battery system and maximize the energy. It is possible to provide a battery control device capable of achieving both utilization.

[Second Embodiment]
The second embodiment will be described with reference to FIGS. 14 to 18. In the first embodiment, the configuration diagram of the battery system shown in FIG. 1, the diagram showing the circuit configuration of the cell control unit shown in FIG. 2, and the block configuration diagram of the battery control unit shown in FIG. 3 are the present embodiment. Since the same applies to the form, the illustration and description thereof will be omitted.

In the first embodiment, the storage unit 180 stores a limit threshold map corresponding to the frequency of short-time energization and the frequency of long-term energization as illustrated in FIGS. 7 (a) and 7 (b). The battery control device that limits the electric power by selecting the voltage difference limit threshold map or the current limit threshold map corresponding to the load feature amount is described. In the second embodiment, the battery control device that limits the power using the power limit rate map corresponding to the load feature amount will be described.

FIG. 14 is a block configuration diagram of the power limit rate calculation unit 154'in the second embodiment. The power limit rate calculation unit 154'has a threshold value calculation unit 154-2', a load determination index calculation unit 154-3', a limit rate calculation unit 154.4', and a limit start / end threshold value determination unit 154-5'. It is composed of.

FIG. 15 is a diagram showing a limit start / end threshold table. The limit start / end threshold table stores the limit start threshold (Th1) and the limit end threshold (Th2) corresponding to the load feature amount (energization time). For example, when the load feature amount (energization time) is 5 seconds or more and less than 30 seconds, the limit start threshold value is Th1-1 and the limit end threshold value is Th2-1. For example, the longer the energization time, the smaller the limit start threshold value and the limit end threshold value are set. The limit start / end threshold table is stored in the storage unit 180 in advance.

The limit start / end threshold determination unit 154-5'determines the limit start threshold and the limit end threshold corresponding to the input load feature amount with reference to the limit start / end threshold table shown in FIG. The determined limit start threshold value and limit end threshold value are transmitted to the limit rate calculation unit 154-4'.

The threshold value calculation unit 154-2'stores one average limit threshold value map among the limit threshold value maps described with reference to FIG. 7. Then, the threshold value calculation unit 154-2'determines and outputs the voltage difference limit value corresponding to the temperature of the secondary battery and the predetermined time window Tw based on the stored limit threshold value map.

The load determination index calculation unit 154-3'calculates and outputs the load determination index based on the voltage difference limit value, the voltage of the secondary battery, and the SOC. Since the calculation of the load determination index is the same as the calculation by the load determination index calculation unit 154-3 described in the first embodiment, the description thereof will be omitted.

The limit rate calculation unit 154-4'calculates and outputs the power limit rate based on the power limit rate map corresponding to the limit start threshold value and the limit end threshold value and the load determination index.

16 (a) and 16 (b) are power limit rate maps in which the load determination index and the power limit rate in the limit rate calculation unit 154-4'are associated with each other. In FIGS. 16A and 16B, the horizontal axis represents the load determination index and the vertical axis represents the power limit rate. These power limit rate maps show maps defined by the limit start threshold value (Th1) and the limit end threshold value (Th2) in the limit start / end threshold value table shown in FIG. The power limit rate map according to these load features was obtained in advance by a charge / discharge test of the secondary battery, and reflects the limiting characteristics of the secondary battery. The power limit rate map may be stored in the storage unit 180, and is calculated based on the limit start threshold value (Th1) and the limit end threshold value (Th2) of the limit start / end threshold value table stored in the storage unit 180. It may be generated.

FIG. 16A shows a case where the frequency of energization for a short time is high. In this figure, the limit start threshold Th1-1 and the limit end threshold Th2-1 are set in a range in which the load determination index is relatively large. The power output is not limited by the load determination index below the limit start threshold Th1-1. The power output is gradually limited from the limit start threshold Th1-1, and the power is completely limited at the limit end threshold Th2-1.

FIG. 16B shows a case where the frequency of energization for a long time is high. The limit start threshold value Th1-2 and the limit end threshold value Th2-2 are set in a range in which the load determination index is smaller than that in the case where the energization frequency for a short time is high. This makes it possible to set stricter restrictions than in the case of short-time energization.

FIG. 17 is a flowchart showing the operation of the battery control unit according to the second embodiment.
When the vehicle start signal is received in step S201, the process proceeds to the next step S202. In step S202, the charge / discharge frequency calculation unit 153 reads out the frequency information of the energization time until the end of the previous run, that is, the energization time number table from the storage unit 180, and proceeds to the next step S203.

In step S203, the most frequent (number of times) energization time is determined as the load feature amount from the read energization time number table, and the process proceeds to step S204.
In step S204, the limit start / end threshold table corresponding to the determined energization time, that is, the load feature amount is read from the storage unit 180, and the limit start threshold and the limit end threshold are determined. Then, the frequency information of the energization time stored in the charge / discharge frequency calculation unit 153, that is, the energization time frequency table is cleared.

In step S205, the power limit rate calculation unit 154'calculates the power limit rate based on the power limit rate map corresponding to the determined limit start threshold value and limit end threshold value. Then, the power limit rate reflection unit 155 calculates the power limit value based on the input / output possible power and the power limit rate. The calculated power limit value is output to the vehicle control unit 200. The vehicle control unit 200 drives the inverter 400 to limit the input / output power to the secondary battery so as not to exceed the input power limit value. In addition, the charge / discharge frequency calculation unit 153 newly updates the frequency information of the energization time.

In step S206, it is determined whether or not the vehicle stop signal has been received. Until the vehicle stop signal is received, the operation according to step S205 is continued, and after receiving the vehicle stop signal, the frequency information of the energization time, that is, the energization time number table is stored in the storage unit 180, and the battery control unit 150 operates. To stop.

18 (a), (b), and (c) show the battery power, the load determination index, and the SOHR when the present embodiment is applied, respectively. Pchg is the power limit value on the charging side, and Pdis is the power limit value on the discharging side. When the vehicle stop signal is received, the frequency information is stored, and when the vehicle start signal is received, the limit start threshold value and the limit end threshold value are determined based on the stored frequency information. As a result, when the power limit rate map corresponding to the limit start threshold value and the limit end threshold value corresponding to the long energization time is applied, the load determination index exceeds the threshold value as shown in FIG. 18 (b). As a result, as shown in FIG. 18A, the power is limited and the transient use of the battery is suppressed. Then, as shown in FIG. 18C, it can be seen that SOHR is suppressed and the deterioration of the secondary battery is suppressed also in the region Q ″.

According to this embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, appropriately suppress the deterioration of the secondary battery, and as a result, protect the battery system and maximize the energy. It is possible to provide a battery control device capable of achieving both utilization.

[Third Embodiment]
In the first embodiment and the second embodiment, the limit threshold map and the power limit rate map corresponding to the most frequent energization time are used for the load feature amount based on the frequency information of the energization time. In the third embodiment, the current value is frequency-analyzed (Fourier transform), the power spectrum corresponding to the frequency is obtained, the limit threshold map corresponding to the frequency having the highest power spectrum is selected, and the load determination index is calculated. ..

The third embodiment will be described with reference to FIGS. 19 to 22.
In the first embodiment, the configuration diagram of the battery system shown in FIG. 1, the diagram showing the circuit configuration of the cell control unit shown in FIG. 2, and the block configuration diagram of the battery control unit shown in FIG. 3 are the present embodiment. Since the same applies to the form, the illustration and description thereof will be omitted.
The battery control unit 150 in this embodiment has the same configuration as that shown in FIG. 3 described in the first embodiment, but the processing content of the charge / discharge frequency calculation unit 153 in the battery control unit 150 is different.

The operation of the charge / discharge frequency calculation unit 153 in the present embodiment will be described with reference to FIGS. 19 and 20. FIG. 19 is a diagram showing a current flowing through a secondary battery and a sampling point. The horizontal axis shows time and the vertical axis shows current. As shown in FIG. 19, the charge / discharge frequency calculation unit 153 in the present embodiment samples the input current value in a predetermined sampling cycle during one running of the vehicle or until a predetermined number of sampling points can be secured. Then, frequency analysis (Fourier transform) is performed using the sampled results, and the power spectrum for each frequency is calculated.

FIG. 20 is a diagram showing the relationship between the power spectrum and the frequency. The horizontal axis shows the frequency and the vertical axis shows the power spectrum. In this embodiment, the frequency corresponding to the highest intensity power spectrum is specified, and the limit threshold map is determined based on the specified frequency.

21 (a) and 21 (b) are diagrams showing an example of a limit threshold map in the present embodiment. FIG. 21A shows a limit value when the load frequency is high, and FIG. 21B shows a limit value when the load frequency is low. The pattern with a high frequency, that is, the pattern with a high frequency of switching between charging and discharging as shown in FIG. 8A, is the pattern with a short continuous energizing time described in the first embodiment, that is, charging and discharging are performed in a short time. It is considered that the frequency of switching patterns is high. Therefore, the relatively loose limiting characteristic as shown in FIG. 21A is applied. On the other hand, a pattern having a low frequency, that is, a pattern in which the frequency of switching between charging and discharging as shown in FIG. 8B is low is a pattern in which the continuous energizing time is long as described in the first embodiment, that is, charging or discharging It is considered that the frequency of long-lasting patterns is high. Therefore, a relatively strict limiting characteristic as shown in FIG. 21 (b) is applied.

FIG. 22 is a flowchart showing the operation of the battery control unit according to the third embodiment.
When the vehicle start signal is received in step S301, the process proceeds to the next step S302. In step S302, the result of frequency analysis based on the current data traveled last time is read from the storage unit 180, and the process proceeds to the next step S303.

In step S303, the frequency component having the highest power spectrum is extracted from the read frequency analysis result, and the process proceeds to step S304.
In step S304, the limit threshold map corresponding to the extracted frequency component is read from the storage unit 180 and determined.

In step S305, the power limit value is calculated based on the determined limit map, the current data during traveling is measured, and when the required number of samples is obtained, frequency analysis (Fourier transform) is performed. Then, the calculated power limit value is output to the vehicle control unit 200. The vehicle control unit 200 drives the inverter 400 to limit the input / output power to the secondary battery so as not to exceed the input power limit value.

In step S306, it is determined whether or not the vehicle stop signal has been received. Until the vehicle stop signal is received, the operation according to step S305 is continued, and after receiving the vehicle stop signal, the frequency analysis result based on the running current data is stored in the storage unit 180, and the battery control unit 150 operates. Stop.

In the present embodiment, the limit threshold value corresponding to the high frequency of the spectrum is set by using the limit threshold value map according to the frequency. However, the frequency is the same as the content described in the second embodiment. The restriction start threshold value and the restriction end threshold value may be changed accordingly. That is, when the high frequency of the spectrum is in the high frequency region, the limitation is applied in the region where the load determination index is high as shown in FIG. 16A, and when the high frequency of the spectrum is in the low frequency region, FIG. Limit control is performed so as to limit from the area where the load determination index is small, such as 16 (b).

According to this embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, appropriately suppress the deterioration of the secondary battery, and as a result, protect the battery system and maximize the energy. It is possible to provide a battery control device capable of achieving both utilization.

According to the embodiment described above, the following effects can be obtained.
(1) The battery control device (battery control unit 150), which is connected to the secondary battery 110 and controls the charging / discharging of the secondary battery 110, is based on the frequency of charging and discharging of the secondary battery 110 in a predetermined period. The charge / discharge frequency calculation unit 153 that obtains the load characteristic amount of the load applied to the secondary battery 110, and the power limit rate calculation unit 154 that obtains the power limit value that limits the input / output possible power of the secondary battery 110 based on the load characteristic amount. , A power limit rate reflecting unit 155 is provided. Thereby, the power to be limited can be determined by more accurately reflecting the usage state of the secondary battery. The power limit rate calculation unit 154 and the power limit rate reflection unit 155 constitute a power limit value calculation unit.

(2) In the battery control device according to (1), the charge / discharge frequency calculation unit 153 obtains the number of times per energization time when the current value flowing through the secondary battery 110 exceeds a predetermined threshold value as the frequency, and the load feature amount. As a result, the energizing time with which the number of times is large is obtained. Thereby, the power to be limited can be determined according to the number of times of energization time of the secondary battery.

(3) The battery control device according to (1) or (2) in the first embodiment is a storage unit that stores a limit threshold map that associates a load feature amount with a voltage or current limit characteristic of a secondary battery. 180 is provided. The power limit rate calculation unit 154 that constitutes the power limit value calculation unit obtains a voltage or current limit value based on a limit threshold map corresponding to the load feature amount obtained from the charge / discharge frequency calculation unit 153, and this limit is obtained. Obtain the power limit rate from the value. The power limit rate reflecting unit 155 obtains a power limit value for limiting the input / output possible power of the secondary battery 110 based on the input / output possible power of the secondary battery 110 and the power limit rate. Thereby, the power to be limited can be determined by more accurately reflecting the usage state of the secondary battery based on the limit threshold map.

(4) The battery control device according to (1) or (2) in the second embodiment is a storage unit 180 that stores a power limit rate map in which a load feature amount and a power limit characteristic of a secondary battery are associated with each other. To be equipped. The power limit rate calculation unit 154 obtains the power limit rate based on the power limit rate map corresponding to the load feature amount obtained from the charge / discharge frequency calculation unit 153. The power limit rate reflecting unit 155 obtains a power limit value for limiting the input / output possible power of the secondary battery 110 based on the input / output possible power of the secondary battery 110 and the power limit rate. As a result, it is possible to more accurately reflect the usage state of the secondary battery based on the power limit rate map and determine the power to be limited.

(5) In the battery control device according to (1) in the third embodiment, the charge / discharge frequency calculation unit 153 obtains the frequency spectrum of the current flowing through the secondary battery 110 as the frequency, and has a high frequency as the load feature amount. Identify the frequency corresponding to the spectrum. Thereby, the power to be limited can be determined according to the frequency spectrum of the current flowing through the secondary battery.

(6) The battery control device according to (5) further includes a storage unit 180 that stores a limiting threshold map that associates the frequency of the current flowing through the secondary battery 110 with the limiting characteristics of the secondary battery 110. The power limit rate calculation unit 154 obtains the power limit rate based on the limit threshold map corresponding to the frequency corresponding to the high frequency spectrum obtained from the charge / discharge frequency calculation unit 153. The power limit rate reflecting unit 155 obtains a power limit value for limiting the input / output possible power of the secondary battery 110 based on the input / output possible power of the secondary battery 110 and the power limit rate. Thereby, the power to be limited can be determined by more accurately reflecting the usage state of the secondary battery.

The present invention is not limited to the above-described embodiment, and other embodiments that can be considered within the scope of the technical idea of the present invention are also included within the scope of the present invention as long as the features of the present invention are not impaired. ..

100 Battery system 110 Combined battery 120 Single battery management unit 130 Current detection unit 140 Voltage detection unit 150 Battery control unit 151 Battery status detection unit 152 Input / output possible power calculation unit 153 Charge / discharge frequency calculation unit 154 Power limit rate calculation unit 155 Power limit Rate reflection unit 156 Charge / discharge limiting unit 180 Storage unit

Claims (6)

A battery control device that is connected to a secondary battery and controls the charging and discharging of the secondary battery.
A charge / discharge frequency calculation unit that obtains a load feature amount of a load applied to the secondary battery based on the frequency of charging and discharging of the secondary battery in a predetermined period.
A power limit value calculation unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the load feature amount .
It is provided with a storage unit for storing a limit threshold map in which the load feature amount and the voltage or current limiting characteristic of the secondary battery are associated with each other.
The power limit value calculation unit is
A power limit rate calculation unit that obtains a voltage or current limit value based on the limit threshold map corresponding to the load feature amount obtained from the charge / discharge frequency calculation unit, and obtains a power limit rate from this limit value.
A battery control device including a power limit rate reflecting unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate . In the battery control device according to claim 1,
The charge / discharge frequency calculation unit obtains the number of times per energization time when the current value flowing through the secondary battery exceeds a predetermined threshold as the frequency, and obtains the energization time with a large number of times as the load feature amount. Device. A battery control device that is connected to a secondary battery and controls the charging and discharging of the secondary battery.
A charge / discharge frequency calculation unit that obtains a load feature amount of a load applied to the secondary battery based on the frequency of charging and discharging of the secondary battery in a predetermined period.
A power limit value calculation unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the load feature amount.
It is provided with a storage unit for storing a power limit rate map in which the load feature amount and the power limit characteristic of the secondary battery are associated with each other.
The power limit value calculation unit is
A power limit rate calculation unit that obtains a power limit rate based on a power limit rate map corresponding to the load feature amount obtained from the charge / discharge frequency calculation unit, and a power limit rate calculation unit that obtains the power limit rate.
A battery control device including a power limit rate reflecting unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate. In the battery control device according to claim 3 ,
The charge / discharge frequency calculation unit obtains the number of times per energization time when the current value flowing through the secondary battery exceeds a predetermined threshold as the frequency, and obtains the energization time with a large number of times as the load feature amount. Device. A battery control device that is connected to a secondary battery and controls the charging and discharging of the secondary battery.
A charge / discharge frequency calculation unit that obtains a load feature amount of a load applied to the secondary battery based on the frequency of charging and discharging of the secondary battery in a predetermined period.
A power limit value calculation unit for obtaining a power limit value that limits the input / output possible power of the secondary battery based on the load feature amount is provided.
The charge / discharge frequency calculation unit obtains the frequency spectrum of the current flowing through the secondary battery as the frequency, and specifies the frequency corresponding to the high frequency spectrum as the load feature amount.
A storage unit for storing a limit threshold map in which the frequency of the current flowing through the secondary battery and the limit characteristic of the secondary battery are associated with each other is provided.
The power limit value calculation unit is
A power limit rate calculation unit that obtains a power limit rate based on a limit threshold map corresponding to a frequency corresponding to the high frequency spectrum obtained from the charge / discharge frequency calculation unit.
A battery control device including a power limit rate reflecting unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate . A battery control device that is connected to a secondary battery and controls the charging and discharging of the secondary battery.
A charge / discharge frequency calculation unit that obtains a load feature amount of a load applied to the secondary battery based on the frequency of charging and discharging of the secondary battery in a predetermined period.
A power limit value calculation unit that obtains a power limit value that limits the input / output possible power of the secondary battery based on the load feature amount.
An input / output power calculation unit that calculates and outputs the input / output power based on the SOC, SOHR, and the temperature of the assembled battery, and the input / output power calculation unit.
It is provided with a power limit rate calculation unit that calculates a power limit rate based on the load feature amount, voltage, temperature, and SOC and outputs the power limit rate to the power limit rate reflection unit.
The power limit rate reflecting unit is based on the input / output possible power and the power limit rate, and is based on the power limit rate calculated by the power limit rate calculation unit and the input / output possible power calculated by the input / output possible power calculation unit. A battery control device that calculates the power limit value .

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