JP2019169994A - Battery control device - Google Patents

Abstract

To provide a battery control device for determining power to be limited, by more accurately reflecting a use state of a secondary battery.SOLUTION: A battery control device 150 for controlling charging/discharging, that is connected with a secondary battery, comprises: a charging/discharging frequency calculation part 153 for determining a load feature amount of a load applied to the secondary battery; and a power limit value calculation part 154 for determining a power limit value at which an input/output possible power of the secondary battery is limited, based on the load feature amount. The charging/discharging frequency calculation part determines a number of times per electricity application time during which a current value flowing through the secondary battery exceeds a predetermined threshold, as a frequency; and determines electricity application time during which the number of times is large, as a load feature amount.SELECTED DRAWING: Figure 3

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 power applied from the secondary battery to a load such as a motor in order to suppress a decrease in output due to deterioration of the secondary battery.

  Patent Document 1 describes a technique for performing charge / discharge restriction when the ratio of the time during which the effective current value exceeds the allowable value within a specified time is higher than a predetermined threshold value.

International Publication WO2015 / 010875

  The degree of deterioration of the secondary battery varies depending on the actual use state of the vehicle or the like. Compared with the technique described in Patent Document 1, it is desired to determine the power to be limited by more accurately reflecting the usage state of the secondary battery.

  A 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, based on the frequency of charging and discharging of the secondary battery in a predetermined period, A charge / discharge frequency calculation unit for obtaining a load feature value of a load applied to the secondary battery; and a power limit value calculation unit for obtaining a power limit value for limiting the input / output possible power of the secondary battery based on the load feature value; Is provided.

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

It is a block diagram of a battery system. It is a figure which shows the circuit structure of a cell control part. It is a block block diagram of a battery control part. (A) (b) It is a figure which shows the electric current which flows through a secondary battery, and the energization time frequency table. It is a block block diagram of a power limiting rate calculating part. It is a graph which shows the relationship between a load determination parameter | index (%) and a power limiting rate. (A) (b) It is a figure which shows an example of a restriction | limiting threshold value map. (A) (b) It is a graph which shows the current waveform from which continuous energization time differs. (A) (b) It is a graph which shows the degradation behavior when the current waveform from which continuous energization time differs is input. It is a flowchart which shows operation | movement of a battery control part. (A) and (b) are graphs respectively showing battery power and SOHR when the present embodiment is not applied. (A) (b) (c) is a graph which respectively shows the battery electric power at the time of applying this embodiment, a load determination parameter | index, and SOHR. (A) (b) It is a figure which shows an example of a restriction | limiting threshold value map. It is a block block diagram of the power limiting rate calculating part in 2nd Embodiment. It is a figure which shows the restriction | limiting start end threshold value table in 2nd Embodiment. (A) (b) It is the power limiting rate map which matched the load determination parameter | index and power limiting rate in 2nd Embodiment. It is a flowchart which shows operation | movement of the battery control part in 2nd Embodiment. (A) (b) (c) is a graph which respectively shows the battery electric power at the time of applying 2nd Embodiment, a load determination parameter | index, and SOHR. It is a figure which shows the electric current and sampling point which flow through the secondary battery in 3rd Embodiment. It is a figure which shows the relationship between the power spectrum and frequency in 3rd Embodiment. (A) and (b) are figures which show an example of the restriction | limiting threshold value map in 3rd Embodiment. It is a flowchart which shows operation | movement 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 also be applied to passenger vehicles such as hybrid vehicles (HEV) and electric vehicles (EV) and industrial vehicles such as hybrid railway vehicles. In the configuration of the embodiment described below, a case where a lithium ion battery is applied as a secondary battery will be described as an example. As the secondary battery, a nickel metal hydride battery, a lead battery, an electric double layer capacitor, a hybrid capacitor, or the like may be used.

[First Embodiment]
A 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 unit cells 111, a unit cell management unit 120 that monitors the state of the unit cell 111, a current detection unit 130 that detects a current flowing through the assembled battery 110, and a group. 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 single battery 111, and the single battery group 112. It consists of.

  The battery control unit 150 includes a battery voltage and temperature of the single cell 111 transmitted from the single cell management unit 120 via the insulating element 170 such as a photocoupler, and a current flowing through the battery system 100 transmitted from the current detection unit 130. 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 a power limit value and the like. In addition, the calculation result performed by the battery control unit 150 is transmitted to the single 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 cells 111 (lithium ion batteries) capable of storing and releasing electrical energy (charging and discharging DC power) in series. One unit cell 111 will be described by taking as an example a case where the output voltage is 3.0 to 4.2 V (average output voltage: 3.6 V), but may have a voltage specification other than this. .

  The unit cells 111 constituting the assembled battery 110 are grouped into a predetermined number of units when managing and controlling the battery state. The grouped unit cells 111 are electrically connected in series to form unit cell groups 112a and 112b. The number of single cells 111 in each of the single cell groups 112a and 112b may be grouped in the same number, for example 1, 4, 6,... Sometimes combined and grouped into different numbers. In the present embodiment, in order to simplify the description, the assembled battery 110 includes four unit cells 111 electrically connected in series to form unit cell groups 112a and 112b, and further electrically connected in series. A total of eight unit cells 111 were connected.

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

FIG. 2 is a diagram illustrating a circuit configuration of the unit cell control unit 121a. The unit cell control unit 121b has the same circuit configuration, and therefore its description is omitted.
The unit 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 unit cell 111. The temperature detection unit 125 measures the temperature of the cell group 112a. The control circuit 123 receives measurement results from the voltage detection circuit 122 and the temperature detection unit 125 and transmits the measurement results to the battery control unit 150 via the signal input / output circuit 124. Note that a circuit for equalizing voltage variations between the single cells 111 caused by self-discharge, current consumption variation, and the like is a general circuit mounted on the single cell control unit 121a, and thus description thereof is omitted.

  The temperature detection unit 125 included in the unit cell control unit 121a in FIG. 2 has a function of measuring the temperature of the unit cell group 112a. The temperature detection unit 125 measures one temperature as a whole of the cell group 112a, and handles the temperature as a temperature representative 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 112 a, or the assembled battery 110. In addition, the temperature detection part 125 may be provided for every single battery 111, temperature may be measured for every single battery 111, and various calculations may be performed based on the temperature for every single battery 111. In this case, the configuration of the unit cell control unit 121 becomes complicated as the number of the temperature detection units 125 increases.

  In FIG. 2, the temperature detection unit 125 is illustrated in a simplified manner, but more specifically, a temperature sensor is installed on 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 unit cell control unit 121a. A function for realizing this series of flows is implemented as a temperature detection unit 125 in the single cell control unit 121, and the voltage detection circuit 122 can be used for measuring temperature information (voltage).

  Returning to the description of FIG. 1, the battery control unit 150 outputs the measurement value of the battery voltage and temperature of the unit cell 111 output from the unit cell management unit 120, the current value from the current detection unit 130, and the output from 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. In addition, 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 occurs in the cell management unit 120. These diagnosis results and abnormal signals are also input to the battery control unit 150. Further, the battery control unit 150 also receives a signal from the vehicle control unit 200 that is a host control device.

  The battery control unit 150 is configured to limit the power for appropriately controlling charging / discharging of the battery pack 110 based on the input information and the current limit value stored in advance in the storage unit 180 and the battery characteristics of the unit cell 111. Calculation of a value, calculation of a state of charge (SOC) or 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 instructions based on the calculation results to the single cell management unit 120 and the vehicle control unit 200.

  The storage unit 180 stores information on the limit values of the battery system 100 and the battery characteristics of the assembled battery 110, the single battery 111, and the single battery 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 unit cell management unit 120, but the battery control unit 150 or the unit cell management unit 120 includes a storage unit. The above information may be stored in the storage unit.

  The battery control unit 150 and the single cell management unit 120 transmit and receive signals through the signal line 160 via an insulating element 170 such as a photocoupler. The insulating element 170 is provided because the operation power supply is different between the battery control unit 150 and the unit cell management unit 120. That is, the unit cell management unit 120 operates by receiving power from the assembled battery 110, whereas the battery control unit 150 uses a battery for on-vehicle auxiliary equipment (for example, a 14V battery) as a power source. The insulating element 170 may be mounted on a circuit board constituting the single cell management unit 120 or may be mounted on a circuit board constituting the battery control unit 150. Depending on the system configuration, the insulating element 170 may be omitted.

  Communication between the battery control unit 150 and the cell control units 121a and 121b in the present embodiment will be described. The unit cell control units 121a and 121b are connected in series according to the order of potential of the unit cell groups 112a and 112b monitored by each unit. The signal transmitted by the battery control unit 150 is input to the single cell control unit 121a through the insulating element 170 through the signal line 160. Similarly, the signal line 160 connects between the output of the unit cell control unit 121a and the input of the unit cell control unit 121b to transmit signals. In the present embodiment, the insulating element 170 is not connected to the connection between the single cell control unit 121a and the single cell control unit 121b, but the insulating element 170 may be used. The output of the single battery control unit 121b is transmitted to the battery control unit 150 via the insulating element 170 and the signal line 160. Thus, the battery control unit 150 and the single cell control units 121a and 121b are connected in a loop shape by the signal line 160. This loop connection may be referred to as a daisy chain connection, a daisy chain connection, or a random 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. Battery system 100 is connected to inverter 400 and drives motor generator 410 based on the energy stored in battery pack 110. When vehicle control unit 200 receives information indicating the power limit value from battery control unit 150, vehicle control unit 200 controls inverter 400 so as not to exceed the power limit value and drives motor generator 410. 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 information on 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 SOC, SOHR, and the temperature of the assembled battery 110. In addition, since the calculation method of SOC, SOHR, and input / output possible electric power is well known, the description is omitted.

  The charge / discharge frequency calculation unit 153 measures the energization time during which the current continuously flows based on the current flowing through the assembled battery 110, and outputs the energization time count 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, is read when the vehicle is next started, and the most frequently energized time is extracted as a load feature amount from the energization time count table, and the power limit rate calculation unit To 154.

  The power limit rate calculating unit 154 calculates a power limit rate based on the load feature amount, voltage, temperature, and SOC, and outputs the calculated power limit rate to the power limit rate reflecting unit 155. The power limit rate reflecting unit 155 calculates a 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.

  4A shows the current flowing through the secondary battery as the assembled battery 110, and FIG. 4B shows the energization time count table. With reference to these drawings, the energization time count table by the charge / discharge frequency calculation unit 153 will be described.

  The horizontal axis of Fig.4 (a) is time, and a vertical axis | shaft shows an example of the electric current which flows through a secondary battery. In FIG. 4A, the current is indicated by a bold line, and the current validity determination threshold is indicated by a one-dot chain line. The region where the absolute value of the current is larger than the current validity determination threshold is the energization time count valid region. The region where the absolute value of the current is below the current validity determination threshold is the energization time count invalid region. The charging / discharging frequency calculation unit 153 starts measuring the energization time when the absolute value of the current is larger than the current effective determination threshold, and ends the measurement when the current is less than the current effective determination threshold. Then, +1 is added to the frequency corresponding to the measured energization time to the energization time count table shown in FIG.

  The energizing time shown in FIG. 4B is divided every 3 seconds, and when the energizing time in which the absolute value of the current shown in FIG. 4A is larger than the current validity determination threshold is 1 second, FIG. 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. 4A is larger than the current validity determination threshold is 5 seconds, the frequency corresponding to the energization times 4 to 6 in FIG. When the energization time in which the absolute value of the current shown in FIG. 4A is greater than the current validity determination threshold is 18 seconds, the frequency corresponding to the energization times 16 to 18 in FIG. In this manner, the charge / discharge frequency calculation unit 153 accumulates frequency information for each energization time in the energization time count table. The energization time count 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 next started. The most frequently energized 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. When the charge / discharge frequency calculation unit 153 determines the load feature value, the charge / discharge frequency calculation unit 153 clears the frequency information in the energization time count table stored therein and restarts 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 includes 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 154-4.

  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, in this embodiment, from a database of limit threshold maps corresponding to energization times. The restriction threshold map (FIG. 7A or 7B) corresponding to the load feature amount is selected. The threshold value calculation unit 154-2 determines a voltage difference limit value corresponding to the temperature of the secondary battery and a predetermined time window Tw based on the selected limit threshold map of FIG. 7 (a) or (b). 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 a load determination index based on the voltage difference limit value, the voltage of the secondary battery, and the SOC. Hereinafter, calculation of the load determination index will be described.
The load determination index calculating 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 voltage (equation (1) below) Hereinafter, the voltage difference is obtained.

Here, ΔV (t) is a 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, the first-order lag filter application result for the square of ΔV (t) in equation (1) is calculated based on the following equation (2) as an index for determining the past usage history of the secondary battery.

Here, ΔV _Fiter (t) is a first-order lag filter application results of ΔV2 (V2), t _s is the control period (sec), 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 unit of voltage is made uniform by the expression (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 a limit threshold (V), and ΔV _Ratio (t) is a load determination index (%).

  Next, the limiting 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 in FIG. 6 indicates the load determination index, and the vertical axis indicates the power limit rate. When the load determination index exceeds Th1, the power limit rate decreases from 1 and becomes 0 when it reaches Th2. 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. Based on the following formulas (5) and (6), the power limiting rate reflecting unit 155 uses the power limiting rate calculated by the power limiting rate calculating unit 154 and the input / output possible power calculated by the input / output possible power calculating unit 152. Calculate the power limit value.

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

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

  FIG. 7A and FIG. 7B are diagrams illustrating an example of the limit threshold map. The limit threshold map is stored in the storage unit 180 corresponding to the load feature amount, in this embodiment, the energization time. In FIGS. 7A and 7B, the horizontal axis represents a time window, and the vertical axis represents a voltage difference limit value. The time window is a time constant of the first-order lag filter and is a predetermined constant.

  FIG. 7A is a limit threshold map corresponding to a 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 in FIG. In addition, the voltage difference limit value decreases as the temperature of the secondary battery decreases. For example, when the calculated load feature amount is continuous energization for a short time, the limit threshold map of FIG. 7A is applied. The limit threshold map corresponding to these load feature amounts is obtained in advance by a charge / discharge test of the secondary battery, and reflects the limit characteristics of the secondary battery. The limit threshold map is not limited to the two shown in FIGS. 7A and 7B, and a plurality of limit threshold maps may be provided corresponding to the energization time.

  FIG. 8A and FIG. 8B are graphs showing current waveforms with 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 bold line, and the current validity determination threshold is indicated by a one-dot chain line. FIG. 8A shows the case of charging / discharging with a high frequency of short-time energization. FIG.8 (b) shows the case of charging / discharging with a high frequency of energization for a long time.

  FIGS. 9A and 9B 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 at the time of charging / discharging with a high frequency of short-time energization. FIG. 9B corresponds to the deterioration behavior when the current waveform of FIG. 8B is repeatedly input, and shows the deterioration behavior at the time of charging / discharging with a high frequency of energization for a long time. As shown in FIGS. 9A and 9B, even if the mean square value of the current or the power is the same, the deterioration behavior is different if the continuous energization time of charging or discharging is different. Specifically, in the case where the continuous energization time is long, there is a region Q in which the resistance sharply increases at a certain time, and the tendency for the deterioration to rapidly progress is seen. In this embodiment, in order to suppress rapid progress of deterioration, a cycle threshold test using pulse currents having the same mean square current value and different continuous energization times is performed, and a limiting threshold is set such that rapid progress of deterioration does not occur. Set up 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 the energization time frequency information until the end of the previous run, that is, the energization time frequency table, from the storage unit 180, and proceeds to the next step S103.

In step S103, an energization time having the highest frequency (number of times) is determined as a load feature amount from the read energization time count table, and the process proceeds to step S104.
In step S104, a limit threshold map corresponding to the determined energization time, that is, the load feature amount is read from the storage unit 180 and selected. And the frequency information of the energization time memorize | stored in the charging / discharging frequency calculating part 153, ie, 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, voltage, temperature, and SOC determined based on the selected limit threshold map. Then, the power limit rate reflecting unit 155 calculates a 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 power that can be input to and output from the secondary battery so as not to exceed the input power limit value. Further, the charge / discharge frequency calculation unit 153 newly updates the frequency information of the energization time.

  In step S106, it is determined whether a vehicle stop signal has been received. Until the vehicle stop signal is received, the operation according to step S105 is continued. After receiving the vehicle stop signal, the energization time frequency information, that is, the energization time frequency table is stored in the storage unit 180, and the battery control unit 150 operates. To stop.

  FIGS. 11A and 11B show battery power and SOHR when this embodiment is not applied. In FIG. 11A, Pchg is a power limit value on the charge side, and Pdis is a power limit value on the discharge side. When this embodiment is not applied, the same limit threshold map is always used without changing the limit threshold map based on the frequency information when the vehicle is started. For this reason, as shown to Fig.11 (a), the restriction | limiting of the electric power reflecting the log | history of charging / discharging until a vehicle stop signal is received cannot be performed. As a result, even if charging / discharging is performed such that a long energization time current occurs frequently before the vehicle stop signal is received, it is not possible to perform appropriate restriction according to this, and FIG. As shown in FIG. 4, there is a region Q in which the internal resistance sharply increases during charging / discharging due to excessive battery use.

  12A, 12B, and 12C show the battery power, the load determination index, and the SOHR when the present embodiment is applied. Pchg is a power limit value on the charge side, and Pdis is a power limit value on the discharge side. When the vehicle stop signal is received, the frequency information is stored. After receiving the vehicle start signal, 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 corresponding to the short energization time is calculated based on the limit threshold map corresponding to the long energization time. It assumes that the case has changed. As a result, as shown in FIG. 12B, the load determination index exceeds the threshold value. Thereby, as shown to Fig.12 (a), electric power is restrict | limited and the transient use of a battery is suppressed. And as shown in FIG.12 (c), SOHR is suppressed also in area | region Q ', and deterioration of a 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 formula (1) to formula (4) based on the voltage difference between the battery voltage and the open circuit voltage. However, the present invention is not limited to this. is not. The load determination index may be calculated based on the following formulas (7) to (9) using the current in the same manner as when the voltage difference is used.

Where, I (t): current (A), I _Fiter (t): I2 primary delay filter application result (A2), t _s : control period (sec), T _w : time window (sec), I _RMS (t): Effective current (A), I _Thresh (t): Current limit value (A), I _Ratio (t): Current base load determination index (%).

  FIGS. 13A and 13B are diagrams illustrating 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, which is the energization time in the present embodiment, according to the characteristics of the secondary battery. In FIGS. 13A and 13B, the horizontal axis represents a time window, and the vertical axis represents a current limit value. FIG. 13A is a limit threshold map corresponding to a case where the frequency of continuous energization for a short time is high. FIG. 13B is a limit threshold map corresponding to the case where the frequency of continuous energization for a long time is high, and the current limit value is also lower than that in FIG. Further, the current limit value decreases as the temperature of the secondary battery decreases. For example, when the calculated load feature quantity is continuous energization for a short time, the limit threshold map of FIG. 13A is applied. The limit threshold map corresponding to these load feature amounts is acquired in advance by a charge / discharge test of the secondary battery.

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

  According to the present embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, and appropriately suppress deterioration of the secondary battery, resulting in protection of the battery system and maximum energy. It is possible to provide a battery control device that can be used at the same time.

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

  In the first embodiment, the limit threshold map corresponding to the frequency of short-time energization and the frequency of long-time energization as illustrated in FIGS. 7A and 7B is stored in the storage unit 180. A battery control device has been described in which a load feature amount having a high frequency (number of times) of energization time is selected and a voltage difference limit threshold map or a current limit threshold map corresponding to the load feature amount is selected to limit power. In the second embodiment, a battery control device that limits power using a power limit rate map corresponding to a load feature amount will be described.

  FIG. 14 is a block configuration diagram of the power limiting rate calculation unit 154 ′ according to the second embodiment. The power limit rate calculation unit 154 ′ includes 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 consists of.

  FIG. 15 is a diagram illustrating a restriction start / end threshold table. The restriction start / end threshold table stores a restriction start threshold (Th1) and a restriction 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 restriction start threshold is Th1-1, and the restriction end threshold is Th2-1. For example, the limit start threshold value and the limit end threshold value are set to be smaller as the energization time is longer. The restriction start / end threshold table is stored in the storage unit 180 in advance.

  The restriction start / end threshold value determination unit 154-5 'determines the restriction start threshold value and the restriction end threshold value corresponding to the input load feature amount with reference to the restriction start / end threshold value 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 map among the limit threshold maps described with reference to FIG. Then, the threshold calculator 154-2 'determines and outputs a voltage difference limit value corresponding to the temperature of the secondary battery and a predetermined time window Tw based on the stored limit threshold map.

  The load determination index calculation unit 154-3 'calculates and outputs a 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 is omitted.

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

  FIGS. 16A and 16B 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 FIG. 16A and FIG. 16B, the horizontal axis represents the load determination index, and the vertical axis represents the power limiting rate. These power restriction rate maps are maps defined by the restriction start threshold (Th1) and the restriction end threshold (Th2) in the restriction start / end threshold table shown in FIG. The power limit rate map corresponding to these load feature amounts is obtained in advance by a charge / discharge test of the secondary battery, and reflects the limit characteristics of the secondary battery. The power limit rate map may be stored in the storage unit 180, or calculated based on the limit start threshold (Th1) and the limit end threshold (Th2) in the limit start / end threshold table stored in the storage unit 180. It may be generated.

  FIG. 16A shows a case where the energization frequency in a short time is high. In this figure, a restriction start threshold Th1-1 and a restriction end threshold Th2-1 are set in a range where the load determination index is relatively large. The power output is not limited by the load determination index equal to or less than 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 energization frequency for a long time is high. The limit start threshold Th1-2 and the limit end threshold Th2-2 are set in a range in which the load determination index is smaller than when the short-time energization frequency is high. Thereby, a restriction | limiting can be set more strictly rather than the case of energization for a short time.

FIG. 17 is a flowchart showing the operation of the battery control unit in 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 the energization time frequency information until the end of the previous run, that is, the energization time frequency table, from the storage unit 180, and proceeds to the next step S203.

In step S203, the energization time having the highest frequency (number of times) is determined as the load feature amount from the read energization time count table, and the process proceeds to step S204.
In step S204, the restriction 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 restriction start threshold and the limit end threshold are determined. And the frequency information of the energization time memorize | stored in the charging / discharging frequency calculating part 153, ie, 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 and limit end threshold. Then, the power limit rate reflecting unit 155 calculates a 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 power that can be input to and output from the secondary battery so as not to exceed the input power limit value. Further, the charge / discharge frequency calculation unit 153 newly updates the frequency information of the energization time.

  In step S206, it is determined whether a vehicle stop signal has been received. Until the vehicle stop signal is received, the operation in step S205 is continued. After receiving the vehicle stop signal, the frequency information of the energization time, that is, the energization time frequency table is stored in the storage unit 180, and the battery control unit 150 operates. To stop.

  18A, 18B, and 18C show the battery power, the load determination index, and the SOHR when this embodiment is applied. Pchg is a power limit value on the charge side, and Pdis is a power limit value on the discharge side. When the vehicle stop signal is received, the frequency information is stored. When the vehicle start signal is received, the restriction start threshold value and the restriction 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 and the limit end threshold corresponding to the long energization time is applied, the load determination index exceeds the threshold as shown in FIG. Thereby, as shown to Fig.18 (a), electric power is restrict | limited and the transient use of a battery is suppressed. Then, as shown in FIG. 18C, it can be seen that SOHR is suppressed even in the region Q ″, and the deterioration of the secondary battery is suppressed.

  According to the present embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, and appropriately suppress deterioration of the secondary battery, resulting in protection of the battery system and maximum energy. It is possible to provide a battery control device that can be used at the same time.

[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 based on the load feature amount frequency information of the energization time. In the third embodiment, the current value is subjected to frequency analysis (Fourier transform), a power spectrum corresponding to the frequency is obtained, a limit threshold map corresponding to the frequency having the highest power spectrum is selected, and a load determination index is calculated. .

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

  Based on FIG. 19, FIG. 20, operation | movement of the charging / discharging frequency calculating part 153 in this embodiment is demonstrated. FIG. 19 is a diagram showing the current flowing through the secondary battery and the sampling points. The horizontal axis represents time, and the vertical axis represents current. As shown in FIG. 19, the charge / discharge frequency calculation unit 153 in this embodiment samples an input current value while the vehicle is traveling at a predetermined sampling cycle or until a predetermined number of sampling points can be secured. Then, frequency analysis (Fourier transform) is performed using the sampled result, and a power spectrum for each frequency is calculated.

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

  FIGS. 21A and 21B are diagrams illustrating an example of the limit threshold map in the present embodiment. FIG. 21A shows the limit value when the load frequency is high, and FIG. 21B shows the limit value when the load frequency is low. A pattern having a high frequency, that is, a high switching frequency between charging and discharging as shown in FIG. 8A is a pattern having a short continuous energization time described in the first embodiment, that is, charging and discharging are performed in a short time. The frequency of switching patterns is considered high. For this reason, a relatively loose restriction characteristic as shown in FIG. On the other hand, a pattern with a low frequency, that is, a low switching frequency between charging and discharging as shown in FIG. 8B is a pattern with a long continuous energization time described in the first embodiment, that is, charging or discharging. It is considered that the frequency of the long-lasting pattern is high. For this reason, a relatively strict restriction characteristic as shown in FIG.

FIG. 22 is a flowchart showing the operation of the battery control unit in 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 the 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 highest frequency component of the power spectrum is extracted from the read frequency analysis result, and the process proceeds to step S304.
In step S304, a limit threshold map corresponding to the extracted frequency component is read from the storage unit 180 and determined.

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

  In step S306, it is determined whether a vehicle stop signal has been received. Until the vehicle stop signal is received, the operation in step S305 is continued. After receiving the vehicle stop signal, the frequency analysis result based on the current data during travel is stored in the storage unit 180, and the battery control unit 150 performs the operation. Stop.

  In the present embodiment, the limit threshold map corresponding to the frequency is used to set the limit threshold corresponding to the high frequency of the spectrum, but the frequency is set in the same manner as described in the second embodiment. The restriction start threshold and the restriction end threshold may be changed accordingly. That is, when the high frequency of the spectrum is in the high frequency region, the restriction is applied in the high load determination index region as shown in FIG. 16A, and when the high frequency of the spectrum is in the low frequency region, Restriction control is performed such that restriction is performed from a region with a small load determination index such as 16 (b).

  According to the present embodiment, it is possible to calculate an appropriate power limit value according to the usage state of the secondary battery, and appropriately suppress deterioration of the secondary battery, resulting in protection of the battery system and maximum energy. It is possible to provide a battery control device that can be used at the same time.

According to the embodiment described above, the following operational effects can be obtained.
(1) A battery control device (battery control unit 150) that is connected to the secondary battery 110 and controls 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. A charge / discharge frequency calculation unit 153 that calculates a load feature amount of a load applied to the secondary battery 110, and a power limit rate calculation unit 154 that calculates a power limit value that limits the input / output power of the secondary battery 110 based on the load feature amount. The power limiting rate reflecting unit 155 is provided. Thereby, the electric power which should be restrict | limited can be determined reflecting the use condition of a secondary battery more appropriately. 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 that the current value flowing through the secondary battery 110 exceeds a predetermined threshold as the frequency, and the load feature amount As a result, the energization time with a large number of times is obtained. Thereby, the electric power which should be restrict | limited can be determined according to the frequency | count of the energization time of a secondary battery.

(3) The battery control device according to (1) or (2) in the first embodiment stores a limit threshold map in which a load feature amount and a voltage or current limit characteristic of a secondary battery are associated with each other. 180. The power limit rate calculation unit 154 constituting 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 The power limit rate is obtained 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. As a result, it is possible to determine the power to be limited 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 stores a power limiting rate map in which a load feature amount and a power limiting characteristic of a secondary battery are associated with each other. Is provided. The power limit rate calculation unit 154 calculates the power limit rate based on the power limit rate map corresponding to the load feature amount calculated by 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 determine the power to be limited by more accurately reflecting the usage state of the secondary battery based on the power limit rate map.

(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 uses the high frequency as the load feature amount. The frequency corresponding to the spectrum is specified. Thereby, the electric power which should be restrict | limited can be determined according to the frequency spectrum of the electric current which flows into a secondary battery.

(6) The battery control device according to (5) further includes a storage unit 180 that stores a limit threshold map that associates the frequency of the current flowing through the secondary battery 110 with the limit characteristics of the secondary battery 110. The power limit rate calculation unit 154 calculates the power limit rate based on the limit threshold map corresponding to the frequency corresponding to the high frequency spectrum determined by 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 electric power which should be restrict | limited can be determined reflecting the use condition of a secondary battery more appropriately.

  The present invention is not limited to the above-described embodiment, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention as long as the characteristics of the present invention are not impaired. .

DESCRIPTION OF SYMBOLS 100 Battery system 110 Battery pack 120 Single battery management part 130 Current detection part 140 Voltage detection part 150 Battery control part 151 Battery state detection part 152 Input / output possible electric power calculation part 153 Charge / discharge frequency calculation part 154 Power limit rate calculation part 155 Power limit Rate reflecting unit 156 Charging / discharging limiting unit 180 Storage unit

Claims (6)

A battery control device that is connected to a secondary battery and controls charging and discharging of the secondary battery,
A charge / discharge frequency calculation unit for obtaining a load feature amount of a load applied to the secondary battery based on the frequency of charge and discharge in a predetermined period of the secondary battery;
A battery control apparatus comprising: a power limit value calculation unit that obtains a power limit value that limits input / output possible power of the secondary battery based on the load feature amount. 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 apparatus. The battery control device according to claim 1 or 2,
A storage unit that stores a limit threshold map that associates the load feature amount with a voltage or current limit characteristic of the secondary battery;
The power limit value calculator is
Based on a limit threshold map corresponding to the load feature amount determined by the charge / discharge frequency calculation unit, a limit value of voltage or current is determined, and a power limit rate calculation unit that calculates a power limit rate from the limit value;
A battery control apparatus comprising: a power limit rate reflecting unit that obtains a power limit value that limits input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate. The battery control device according to claim 1 or 2,
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 calculator is
Based on a power limit rate map corresponding to the load feature amount determined by the charge / discharge frequency calculation unit, a power limit rate calculation unit for determining a power limit rate;
A battery control apparatus comprising: a power limit rate reflecting unit that obtains a power limit value that limits input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate. The battery control device according to claim 1,
The said charge / discharge frequency calculating part is a battery control apparatus which calculates | requires the frequency spectrum of the electric current which flows into the said secondary battery as said frequency, and specifies the frequency corresponding to a high frequency spectrum as said load feature-value. The battery control device according to claim 5,
A storage unit that stores a limit threshold map that associates the frequency of the current flowing through the secondary battery with the limit characteristics of the secondary battery;
The power limit value calculator is
Based on a limit threshold map corresponding to the frequency corresponding to the high frequency spectrum determined by the charge / discharge frequency calculation unit, a power limit rate calculation unit for determining a power limit rate;
A battery control apparatus comprising: a power limit rate reflecting unit that obtains a power limit value that limits input / output possible power of the secondary battery based on the input / output possible power of the secondary battery and the power limit rate.

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