JP6242516B1 - Battery management device - Google Patents

Abstract

When a circuit configuration equipped with a battery monitoring IC is adopted and cell balance switches of adjacent cells cannot be turned on at the same time, there is a problem that the time required for cell balance becomes long. A battery cell calculates a time required for cell balance until full charge, selects a target cell to be preferentially balanced based on this time, performs cell balance, and is used as a balancer drive target. The battery management device is configured to perform cell balancing based on the selection result of the balance driving target cell until the maximum time value of the cell being matched with the maximum time value of the cell being the balancer stop target. [Selection] Figure 2

Description

  The present invention relates to a battery management apparatus using a cell balance method for equalizing each battery cell voltage of a battery pack.

  In recent years, secondary batteries have come to be used as household or industrial emergency power supplies and electric vehicle drive power supplies. Since this secondary battery is limited in electromotive voltage and electric capacity, it is common to use a plurality of secondary batteries connected in series and parallel depending on the application. A battery having such a structure is also referred to as an assembled battery or simply a battery pack. (Hereinafter referred to as a battery pack.) A battery constituting a unit constituting the battery pack is referred to as a battery cell.

By the way, when the battery pack is used for a long time or when some of the battery cells are replaced with new batteries, the capacity varies among the battery cells. When this capacity variation occurs, specific battery cells may overdischarge or overcharge when the battery pack is charged and discharged, resulting in a decrease in the capacity of the battery pack and a deterioration of the battery pack. And shorten the life.
In order to eliminate such variation in the capacity of the battery pack, conventionally, the balance control of the battery cells is performed so that all the battery cells are fully charged when the battery pack is fully charged. (See Patent Document 1)

In the cell balance control method technique in Patent Document 1, the cell balance resistance installed in each battery cell is controlled using the lowest voltage among the battery cells as a cell balance target value.
On the other hand, since the battery cells have different capacities as described above, the charging rate of each battery cell during charging does not change uniformly. That is, when the charge amount changes, the battery cell having the lowest voltage also changes.
Therefore, since the battery cell that is the lowest voltage during charging will change with respect to the battery cell that was the lowest voltage before charging, cell balancing will be performed to battery cells that do not need to be cell-balanced originally, There are problems such as wasteful consumption of charging energy and extended charging time.

  For this reason, the technique which solves the above-mentioned problem by setting the target cell voltage according to the charge state of each battery cell is proposed. (Patent Document 2)

Japanese Patent No. 3882663 Japanese Patent Application No. 2006-107772

In the above patent application, all balancers of cells other than the target cell are turned on, but when the balancer of an adjacent cell is turned on, in addition to the closed loop current for one cell, a plurality of cell balance switches are used. A current in which the sum of the voltages of the cells is added to the balancer resistance flows, and the cell balance switch generates heat, leading to a reduction in life. For this reason, a high voltage resistance is required for the cell balance switch. Generally, a cell balance switch having a high voltage resistance is expensive and large in size. When such a cell balance switch is used, the price of the device is high. Increases device size.
Therefore, in order to reduce the cost and size of the device, use a low-price, small, low-voltage cell balance switch, so that adjacent cells are not turned on at the same time, for example, even-numbered and odd-numbered cell balance switches Are alternately turned on at regular intervals. However, in this case, there is a problem that the cell balance time becomes long.

In order to make the above operation easy to understand, the remaining time required to balance each battery cell to the target cell voltage is Trem [min] (minutes), and FIG. 19 shows the transition of the time Trem during cell balancing. Based on
FIG. 19 shows an example of a battery pack in which eight battery cells (# 1 to # 8) are connected in series, and cell balance switches of odd-numbered cells and even-numbered cells are alternately switched every fixed period (1 minute). It shows the transition of the time Trem of the cells # 1 to # 8 when the cell balance is performed after being turned on.

First, at time t0 when the cell balance is started, the cell balances of # 1, # 5, and # 7 of the odd cells are turned on, and the other cells are turned off. For the odd cell # 3, the time Trem is already 0 minutes, and the cell balance is turned off.
Next, at time t1 when the cell balance is continued for one minute, the cell balances of # 2, # 4, # 6, and # 8 of even-numbered cells are turned on, and the other cells turn off the cell balance. At the time t1, the time Trem of the odd cells # 1, # 5, and # 7 is decreased by 1 minute from the time t0.

Furthermore, at time t2 when the cell balance is continued, the cell balances of the odd-numbered cells # 1, # 5, and # 7 are turned on, and the other cells are turned off. At the time t2, the time Trem of the even cells # 2, # 4, # 6, and # 8 is decreased by 1 minute from the time t1.
Next, at time t3 when the cell balance is continued for 1 minute, the cell balances of the even cells # 2, # 4, # 6, and # 8 are turned on, and the other cells are turned off. At the time t3, the time Trem of the odd-numbered cells # 1, # 5, and # 7 is decreased by 1 minute from the time t2.

Similarly, when the cell whose time Trem is 0 minutes is turned off and the cell balance is alternately performed on the odd and even cells, at time t4 after 36 minutes from t3, The cells other than the cell # 4 have a time Trem of 0 minutes.
After that, if cell balancing is performed alternately for odd and even cells, the time Trem of all cells becomes 0 minutes at time t5 after 21 minutes from t4, and cell balancing is completed.
As a result, it takes 60 minutes in total to reach the time point t5 from the time point t0.

  The present invention has been made to solve the above problems, and provides a battery management device capable of shortening the cell balance time even when the cell balance switches of adjacent cells cannot be turned on simultaneously. It is aimed.

The battery management device according to the present invention includes a cell voltage detecting means for detecting a voltage (V _n ) between terminals in a plurality of battery cells constituting a battery pack, connected in parallel to each of the battery cells, and connected to each of the battery cells. A balancer that controls the charging current that flows, current detection means that detects charge / discharge current (I) of the battery pack, and a remaining charge amount (Qrem _n ) of each battery cell based on the charge state of the battery pack Cell remaining charge amount calculating means; remaining charge amount maximum value calculating means for calculating a maximum value (Qrem_max) from the remaining charge amount (Qrem _n ) of each battery cell; the cell remaining charge amount calculating means; and the remaining charge amount remaining charging amount calculated by the maximum value calculation means (Qrem _n) and the residual charge amount maximum value (Qrem_max Terminal said detected and the cell balancer consumed charge amount calculating means for calculating a charge amount (Qc _n) of each battery cell that requires consumption by the balancer until fully charged, by the cell voltage detecting unit and a The balancer consumption current (Ib) consumed by the balancer per unit time based on the inter-voltage (V _n ), the charge / discharge current (I) detected by the current detection means, the internal resistance of each battery cell, and the resistance of the balancer _n ), each cell balancer consumption current calculation means for calculating _n ), each cell balancer consumption charge amount calculation means, and the charge amount (Qc _n ) and balancer consumption current (Ib _n ) calculated by each cell balancer consumption current calculation means. each cell remaining cells to calculate the respective battery cells the cell balance the time required until the full charge (Trem _n) from Lance time calculating means, said selected as a balance stop target cell both sides of the balance-target cell with time required for cell balancing of each battery cell (Trem _n) is a balance-target cell a cell that the maximum value Further, in the cells not determined as the balance drive target cell or the balance stop target cell, the cell having the maximum time (Trem _n ) required for cell balance is set as the balance drive target cell and the balance drive target. Selecting both sides of the cell as a balance stop target cell, and balance drive target cell selection means for selecting the balance drive target cell or the balance stop target cell until all the cells become the balance drive target cell or the balance stop target cell; According to the output of the balance drive target cell selection means. It is characterized in that so as to drive and control the balancer.

  According to the battery management device of the present invention, a circuit configuration equipped with a battery monitoring IC is adopted, and after considering the capacity variation between the battery cells, a target cell to be preferentially balanced and driven is selected to achieve cell balance. By implementing this, it becomes possible to shorten the cell balance time.

It is a schematic diagram which shows the electric vehicle to which the battery management apparatus which concerns on Embodiment 1 of this invention is applied. It is a block diagram which shows the specific structure of the battery management apparatus which concerns on Embodiment 1 of this invention. It is a flowchart for demonstrating operation | movement of the battery management apparatus which concerns on Embodiment 1 of this invention. 4 is a flowchart for explaining a voltage value storing operation of a cell in FIG. 3. It is a flowchart for demonstrating the electric current value storage operation | movement in FIG. It is a flowchart for demonstrating the capacity | capacitance estimation operation | movement of each cell in FIG. 4 is a flowchart for explaining a calculation operation of internal resistance estimation of each cell in FIG. 3. 4 is a flowchart for explaining an operation of calculating a remaining charge amount of each cell in FIG. 3. 4 is a flowchart for explaining an operation of calculating a maximum remaining charge amount of each cell in FIG. 3. It is a flowchart for demonstrating calculation operation | movement of each cell balancer consumption charge amount in FIG. 4 is a flowchart for explaining a calculation operation of each cell balancer consumption current in FIG. 3. 4 is a flowchart for explaining a calculation operation of each cell remaining cell balance time in FIG. 3. 4 is a flowchart for explaining an operation of calculating a balance drive target remaining cell balance time maximum value in FIG. 3. FIG. 4 is a flowchart for explaining a calculation operation of a balance stop target remaining cell balance time maximum value in FIG. 3. FIG. 4 is a flowchart for explaining a selection operation of a balance drive target cell in FIG. 3. 4 is a flowchart for explaining a balance method selection operation in FIG. 3; It is a flowchart for demonstrating the cell balance drive determination in FIG. It is a schematic diagram for demonstrating transition of the remaining cell balance time in the cell balance by this invention. It is a schematic diagram for demonstrating transition of the remaining cell balance time in the cell balance in a prior art.

Embodiment 1 FIG.
Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an electric vehicle 100 to which a battery management device according to Embodiment 1 of the present invention is applied.
In the figure, an electric vehicle 100 includes a vehicle control device 101 that controls driving and charging of the electric vehicle, a driving motor 102 that drives wheels, an inverter 103 that controls the driving motor 102, and the inverter 103. The battery pack 104 that supplies electric power and the battery management device 105 that monitors the battery pack 104 are configured to charge the battery pack 104 via an external charger 106.
Here, the vehicle control device 101 requests the inverter 103 to drive the drive motor 102 to drive the electric vehicle, and the inverter 103 drives the drive motor 102 using the electric power of the battery pack 104. . Further, the battery pack 104 is monitored by the battery management device 105, and a battery state signal from the battery management device 105 is sent to the vehicle control device 101. The vehicle control device 101 performs travel control according to the battery state. Is configured to realize.
Furthermore, the vehicle control device 101 instructs the charger 106 to charge the battery pack 104 in response to a charge request from the outside, and controls charging to the battery pack 104.

  2 shows a specific configuration of the battery pack 104 and the battery management device 105 in FIG. 1. In FIG. 2, the battery pack 104 is composed of a plurality of battery cells 104a, 104b,. Since the output voltage of each of the battery cells 104a, 104b,... 104n is low, the battery pack 104 is configured so that an output voltage necessary for driving the vehicle can be obtained by connecting in series. . The battery pack 104 is connected to a current detection unit 107 that detects a charge / discharge current of the battery pack 104.

  On the other hand, the battery management device 105 includes a balancer 201 that adjusts the cell voltages of the battery cells 104a, 104b,. (Microcomputer) 203 and a microcomputer 301 that performs cell balance control, monitor the cell voltages of the battery cells 104a, 104b,... 104n, and make the cell voltages of all the battery cells 104a, 104b,. It is configured to perform control.

Here, the balancer 201 is composed of a series circuit of balancer resistors 201a, 201b,... 201n and cell balance switches 202a, 202b,... 202n, and is connected in parallel to the battery cells 104a, 104b,. . That is, based on the cell balance control instruction from the microcomputer 301, the cell balance switches 202a, 202b,... 202n of the battery cells 104a, 104b,. , 201b,... 201n are controlled to perform cell balance.
In addition, the battery monitoring IC 203 sequentially switches the voltage between the terminals of the battery cells 104a, 104b,... 104n by the multiplexer 203a, detects it by the cell voltage detecting means 203b, and outputs the detected cell voltage to the microcomputer 301.

Further, the microcomputer 301 determines which battery cell needs the cell balance from the battery cell voltage detected by the cell voltage detection means 203b, and performs cell balance drive control.
Specifically, the microcomputer 301 detects the cell voltage value storage unit 302 that stores the cell voltage from the cell voltage detection unit 203b in a RAM (Random Access Memory) for each battery cell, and the charge / discharge current of the battery pack 104. Current value storage means 303 for storing the current value from the current detection means 107 in the RAM, each cell capacity estimation means 304 for estimating the capacity of each battery cell 104a, 104b,... 104n, and each battery cell 104a, 104b,. Each cell internal resistance estimation means 305 for estimating the internal resistance of 104n and a cell balance control means 306 for performing cell balance control are provided.

The cell balance control means 306 includes each cell remaining charge amount calculating means 401 for calculating each cell remaining charge amount Qrem _n which is a remaining charge amount until the battery cells 104a, 104b,. Remaining charge amount maximum value calculation means 402 for calculating the remaining charge amount maximum value Qrem_max from the remaining charge amount Qrem _n , and each of the battery cells 104a, 104b,. calculating each cell balancer consumed charge amount calculating means 403 for calculating each cell balancer consumed charge amount Qc _n, each battery cell 104a, 104b, ... each cell balancer consumption current Ib _n is a current flowing through the balancer 201 104n Each cell balancer consumption current calculation means 404 and each battery cell 104a, 104b,... 104 Each cell remaining cell balance time calculating means 405 for calculating each cell remaining cell balance time Trem _n , which is a time required for cell balance until n is fully charged.

In addition, the cell balance control unit 306 calculates the maximum remaining cell balance time Tremtg_max among the target cells to be preferentially subjected to balance driving based on the balance driving target selection result from the balance driving target cell selecting unit 408 described later. Balance driving target remaining cell balance time maximum value calculating means 406 and balance driving target cell selection means 408, the balance driving target cell calculation means 408 calculates the remaining cell balance time maximum value Tremountg_max in the balance stopping target cell. remaining cell balance time and maximum value calculating unit 407, the respective cells remaining cell balance time Trem _n balance driven remaining cell balance time maximum Tremtg_max and the balanced shutdown target remaining cell balance time maximum Tremuntg_max, preferentially The cell selected as the balance drive target by the balance drive target cell selection means 408 for selecting the target cell to be balanced, the balance drive target remaining cell balance time maximum value Tremtg_max and the balance stop target remaining cell balance time maximum value Tremountg_max described above. A balance method selection means 409 for selecting a balance method for performing cell balance on the cell, or alternately performing cell balance on odd / even cells every predetermined period, and according to a balance drive target cell selection result and a balance method selection result The battery balance driving determination means 410 is configured to determine a battery cell target to perform balancer driving and output a balancer driving signal.

Next, the operation of the battery management device configured as described above will be described.
First, the battery monitoring IC 203 in the battery management device 105 outputs the cell voltage read from the battery cells 104a, 104b,... 104n by the cell voltage detection unit 203b to the cell voltage value storage unit 302.
Based on this output, the cell voltage value storage unit 302, each battery cell 104a every predetermined period, 104b, ... stores the cell voltage _{V n} of 104n inside the RAM, each battery cell 104a, 104b, ... cell 104n The voltages are collectively output to the cell balance control means 306.

In addition, the current detection unit 107 detects the charge / discharge current of the connected battery pack 104 and outputs it to the current value storage unit 303.
In response to this output, the current value storage means 303 stores the current value I in the internal RAM at regular intervals and outputs it to the cell balance control means 306.
Further, each cell capacity estimation means 304, each battery cell 104a, 104b, the capacitance Cp _n of ... 104n estimated, outputs to the cell balance control section 306. As a cell capacity estimation method, for example, a method described in Japanese Patent Application Laid-Open No. 2012-181666 is known.
Each cell internal resistance estimation unit 305 estimates each cell internal resistance Rin _n and outputs it to the cell balance control unit 306. As a method for estimating cell internal resistance, for example, a method described in Japanese Patent Application Laid-Open No. 2014-6245 is known.

Each cell remaining charge amount calculation means 401 in the cell balance control means 306 receiving each output as described above, the current value I output from the current value storage means 303 and each battery output from each cell capacity estimation means 304. cell 104a, calculated 104b, ... each battery cell 104a than the capacitance Cp _n of 104n, 104b, the charging rate of ... 104n, further calculates a remaining charge amount until the full charge of each battery cell from the charging rate, which Are output to the remaining charge amount maximum value calculation means 402 as each remaining battery charge amount Qrem _n .
This remaining charge amount maximum value calculating means 402 calculates the maximum value from each cell remaining charge amount Qrem _n output from each cell remaining charge amount calculating means 401, and uses this as the remaining charge amount maximum value Qrem_max. Output to charge amount calculation means 403.

Each cell balancer consumption charge amount calculation means 403 is a difference between the remaining charge amount Qrem_max output from the remaining charge amount maximum value calculation means 402 and each cell remaining charge amount Qrem _n output from each cell remaining charge amount calculation means 401. more, each battery cell 104a, 104b, ... 104n calculates each cell balancer consumed charge amount Qc _n is the charge required amount consumed by the balancer 201 until fully charged, the output to each cell remaining cell balance time calculating unit 405 To do.

Each cell balancer consumption current calculation means 404 includes a current value I output from the current value storage means 303, each cell internal resistance Rin _n output from each cell internal resistance estimation means 305, and a microcomputer (not shown). from the recorded balancer resistance value Rb as eigenvalues, each battery cell 104a, 104b, ... is calculated each cell balancer consumption current Ib _n is a current flowing through the balancer 201 104n, to each cell remaining cell balance time calculating unit 405 Output.
Each cell remaining cell balance time calculating unit 405, and each cell balancer consumed charge amount Qc _n output from each cell balancer consumed charge amount calculating unit 403, each cell balancers output from each cell balancer current consumption computing unit 404 the current consumption Ib _n, each battery cell 104a, 104b, ... 104n calculates each cell remaining cell balance time Trem _n is the time required to the cell balance until full charge, balance driven remaining cell balance time maximum value Output to the calculation means 406 and the balance stop target remaining cell balance time maximum value calculation means 407.

Balance driven remaining cell balance time maximum value calculating unit 406, and Trem _n output from each cell remaining cell balance time calculating unit 405, the balance-target cell selection result output from the balance-target cell selection means 408 will be described later Thus, Tremtg_max, which is the maximum value of the remaining cell balance time Trem _{n in} the target cells to be preferentially subjected to balance driving, is calculated and output to the balance method selection means 409.
Moreover, balanced shutdown target remaining cell balance time maximum value calculating unit 407, and Trem _n output from each cell remaining cell balance time calculating unit 405, the balance-target cell balance is outputted from the selection unit 408 driving the target cell selection result and it allows to calculate the Tremuntg_max is the maximum value of the remaining cell balance time Trem _n in the balanced shutdown target cell, and outputs it to the balance method selecting means 409.

Next, the balance driving target cell selection unit 408 includes the Trem _n output from each cell remaining cell balance time calculation unit 405, the Tremtg_max output from the balance driving target remaining cell balance time maximum value calculation unit 406, and the balance stop. Based on Tremountg_max output from the target remaining cell balance time maximum value calculation unit 407, a target cell to be preferentially subjected to balance drive is selected, and the selection result is output to the cell balance drive determination unit 410.
In addition, the balance method selection unit 409 performs balance driving based on Tremtg_max output from the balance drive target remaining cell balance time maximum value calculating unit 406 and Tremountg_max output from the balance stop target remaining cell balance time maximum value calculating unit 407. Selects the balance method of whether to perform cell balance for the selected cell, or to perform odd-numbered / even-numbered cell alternating alternately for a certain period of time, and outputs the selection result to the cell balance drive determination means 410 To do.

Further, the cell balancing driver determination unit 410, and Trem _n output from each cell remaining cell balance time calculating unit 405, a balance-target cell selection result output from the balance-target cell selection unit 408, balance mode selection means Based on the balance method selection result output from 409, the battery cell target to perform balancer driving is determined, and a balancer driving signal is output.

Next, a method of calculating the respective cells remaining cell balance time Trem _n in each cell remaining cell balance time calculating unit 405.
Here, the current value I [A], and the capacitance of the battery cell n and _Cp n [Ah], the charging rate of the battery cell n _SOC n [%] is the time integral of the current value I (t) [A] And is expressed by the following equation.

また、バッテリーセルｎの残充電量Ｑｒｅｍ_ｎ［Ａｈ］は、次式で表される。

Further, the remaining charge amount Qrem _n [Ah] of the battery cell n is expressed by the following equation.

さらに、残充電量最大値Ｑｒｅｍ＿ｍａｘ［Ａｈ］は、次式で表される。

Furthermore, the remaining charge amount maximum value Qrem_max [Ah] is expressed by the following equation.

  By the way, in the prior art, the remaining charge amount of the battery cell, which is the lowest cell voltage, does not always become the maximum depending on the battery capacity. The occurrence of consumption was a problem. In order to eliminate this useless cell balance, cell balance control may be performed so that the remaining charge amount is the same in all battery cells, and a battery pack in which a plurality of battery cells 104a, 104b,. In 104, since the charge amount is equally added to all the battery cells 104a, 104b,... 104n, the target of the remaining charge amount may be set to the remaining charge amount maximum value Qrem_max [Ah].

Next, in each battery cell n, a charge amount Qc _n [Ah] required to be consumed by the balancer 201 until full charge is obtained.
The consumed charge amount Qc _n [Ah] in each battery cell n is the difference between the remaining charge amount Qrem _n [Ah] and the remaining charge amount maximum value Qrem_max [Ah], and is expressed by the following equation.

Next, in each battery cell n, a current value Ib _n [A] flowing through the balancer 201 with the cell balance switch 202n turned on is obtained.
Although not shown in FIG. 2, the battery cell n has an internal resistance, that is, a resistance of a series component with respect to the voltage source, and a parallel circuit with the balancer resistance 201n is configured. Therefore, when the current flowing through the battery cell n is I [A], each cell voltage is V _n [V], each cell internal resistance value is Rin _n [Ω], and the balancer resistance value is Rb [Ω], the battery cell The current Ib _n [A] flowing through the n balancers 201 is expressed by the following equation using Kirchhoff's first law and the principle of superposition.

Further, in each battery cell n, each cell remaining cell balance time Trem _n [min], which is a time required for consuming the consumed charge amount Qc _n [Ah] by the balancer, is expressed by the following equation.

Next, the cell balance control operation in the first embodiment will be described based on the flowcharts shown in FIGS.
FIG. 3 is a flowchart for explaining the operation of the battery management apparatus 105, and this operation is executed every predetermined time set in the microcomputer 301.

First, in step S1, the cell voltage value storage means 302 stores the cell voltage acquired from the battery monitoring IC 203 in the RAM sequentially for each cell.
Next, in step S <b> 2, the current value storage unit 303 stores the charge / discharge current of the battery pack 104 acquired from the current detection unit 107 in the RAM.
Next, in step S3, each cell capacity estimation means 304 estimates the capacity of each battery cell 104a, 104b,... 104n, and sequentially stores it in the RAM for each cell.
Next, in step S4, each cell internal resistance estimation means 305 estimates the internal resistance of each battery cell 104a, 104b,... 104n, and sequentially stores it in the RAM for each cell.

Next, in step S5, each cell remaining charge amount calculation means 401 determines the cell voltage of each battery cell 104a, 104b,... 104n stored in step S1 and each battery cell 104a, 104b,. Each cell charge rate is calculated based on the capacity of 104n, each cell remaining charge amount is calculated from each cell charge rate, and each cell is sequentially stored in the RAM.
Next, in step S6, the remaining charge amount maximum value calculating means 402 calculates the remaining charge amount maximum value from each cell remaining charge amount and stores it in the RAM.
Next, in step S7, each cell balancer consumption charge amount calculation unit 403 determines the balancer consumption charge amount that the balancer 201 needs to consume from the remaining charge amount maximum value until the battery cells 104a, 104b,. And is stored in the RAM sequentially for each cell.

Next, in step S8, each cell balancer consumption current calculation means 404 calculates the balancer current value flowing through the balancer 201 with the cell balance switches 202a, 202b,... 202n turned on, and sequentially stores them in the RAM for each cell. .
Next, in step S9, each cell remaining cell balance time calculation means 405 calculates the remaining cell balance time required to consume the balancer consumption charge amount in each battery cell 104a, 104b,. Every time, it is stored in the RAM.

Next, in step S10, the balance drive target remaining cell balance time maximum value calculation means 406 calculates the maximum value from the remaining cell balance time of the battery cells 104a, 104b,... 104n selected as the balance drive target in step S12 described later. Is calculated and stored in the RAM.
Next, in step S11, the balance stop target remaining cell balance time maximum value calculating unit 407 calculates a maximum value from the remaining cell balance times of the balance stop target battery cells 104a, 104b,. Store in RAM.

Next, in step S12, the balance drive target cell selection unit 408 selects a target cell to be preferentially subjected to balance drive based on the calculation results of steps S9 to S11, and stores the selection result in the RAM.
Next, in step S13, the balance method selection unit 409 selects a balance method based on the calculation results of steps S10 to S11, and stores the selection result in the RAM.
Finally, in step S14, the cell balance drive determination means 410 determines which battery cell is to be balanced based on the selection results in steps S12 and S13, and outputs a balancer drive signal.

Next, details of steps S1 to S4 and steps S5 to S14 in FIG. 3 will be described.
FIG. 4 is a flowchart showing details of step S1 (cell voltage value storage processing).
First, in step S1a, the cell voltage detected by the battery monitoring IC 203 is read into the microcomputer 301 via the communication means or the like, and in step S1b, the read cell voltage is stored in the target cell voltage storage RAM. The process of step S1 is performed by the cell voltage value storage unit 302.

FIG. 5 is a flowchart showing details of step S2 (current value storage processing).
In step S21, the charging / discharging current of the battery pack 104 detected by the current detection means 206 is read into the microcomputer 301 via the communication means or the like, and in step S22, the read current value is stored in the current value storage RAM. In addition, the process of step S2 is performed by the current value storage unit 303.

FIG. 6 is a flowchart showing details of step S3 (each cell capacity estimation calculation).
In step S31, the capacity of each battery cell 104a, 104b,... 104n is estimated based on various information of each battery cell 104a, 104b,... 104n, and stored in each cell capacity storage RAM in step S32. The process of step S3 is performed by the cell capacity estimation unit 304.

FIG. 7 is a flowchart showing details of step S4 (estimation calculation of each cell internal resistance).
First, in step S41, the internal resistance of each battery cell is estimated based on various information of each battery cell, and stored in each cell internal resistance storage RAM in step S42. The process in step S4 is performed by each cell internal resistance estimation unit 305.

FIG. 8 is a flowchart showing details of step S5 (calculation of remaining charge amount of each cell).
First, at step S51, determined as the input current value and the cell capacitance Cp _n, each battery cell 104a based on the equation (1), 104b, the charging rate SOC _n of ... 104n, then, at step S52, The remaining charge amount Qrem _n of each battery cell 104a, 104b,... 104n is calculated from the charging rate SOC _{n of} each battery cell based on the above equation (2). Further, in step S53, the remaining charge amount Qrem _n of each battery cell 104a, 104b,... 104n is stored in each cell remaining charge amount storage RAM. In addition, the process of step S5 is performed by each cell remaining charge calculation means 401.

FIG. 9 is a flowchart showing details of step S6 (calculation of maximum remaining charge amount).
First, in step S61, the remaining charge maximum value Qrem_max is calculated from each cell remaining charge amount Qrem _n based on the above equation (3), and in step S62, the maximum value is stored in the remaining charge amount maximum value storage RAM. To do. The process of step S6 is performed by the remaining charge maximum value calculation unit 402.

FIG. 10 is a flowchart showing details of step S7 (each cell balancer consumption charge amount calculation).
First, in step S71, the respective cells remaining charging amount Qrem _n and the remaining charging amount maximum value Qrem_max as input, calculates the respective cell balancer consumed charge amount Qc _n based on the equation (4). Then, storing each cell balancer consumed charge amount Qc _n to each cell balancer consumed charge amount storing RAM in step S72. The process of step S7 is performed by each cell balancer consumption charge amount calculation means 403.

FIG. 11 is a flowchart showing details of step S8 (each cell balancer consumption current calculation).
First, in step S81, each cell voltage V _n , current value I, each cell internal resistance Rin _n, and balancer resistance value Rb recorded in the microcomputer 301 in advance are input and based on the above equation (5). The balancer consumption current Ib _n of each battery cell 104a, 104b,... 104n is calculated. Next, in step S82, the balancer consumption current Ib _n of each battery cell 104a, 104b,... 104n is stored in each cell balancer consumption current storage RAM. The process of step S8 is performed by each cell balancer consumption current calculation unit 404.

FIG. 12 is a flowchart showing details of step S9 (each cell remaining balance time calculation).
First, in step S91, the each cell balancer consumed charge amount Qc _n and each cell balancer consumption current Ib _n as input, the equation (6) each cell based on the remaining cell balance time Trem _n
Is calculated. Next, in step S92, stores the cells remaining cell balance time Trem _n to each cell remaining cell balance time storage RAM. Note that the processing of step S9 is performed by each cell remaining cell balance time calculation means 405.

FIG. 13 is a flowchart showing details of step S10 (calculation of balance drive target remaining cell balance time maximum value).
First, in step S101, from among the cells remaining cell balance time Trem _n, extracts all the time balance driven cell to be selected in step S12 to be described later, it calculates a maximum value Tremtg_max from. In step S102, the maximum value is stored in the balance drive target remaining cell balance time maximum value storage RAM. Note that the processing of step S10 is performed by the balance drive target remaining cell balance time maximum value calculation means 406.

FIG. 14 is a flowchart showing details of Step S11 (calculation of balance stop target remaining cell balance time maximum value).
First, in step S111, from among the cells remaining cell balance time Trem _n, extracts all the time of a cell other than the balance driven cell to be selected in step S12 to be described later, calculates a maximum value Tremuntg_max from. Next, in step S112, the maximum value is stored in the balance stop target remaining cell balance time maximum value storage RAM. Note that the processing in step S11 is performed by the balance stop target remaining cell balance time maximum value calculation unit 407.

FIG. 15 is a flowchart showing details of step S12 (balance drive target cell selection).
First, in step S121, it is determined whether or not it is the time of the first calculation, and if it is the time of the first calculation, the process proceeds to step S125, and if not, the process proceeds to step S122.
Next, in step S122, it is determined whether or not each cell remaining cell balance time Trem _n is all 0 [minutes]. If all the remaining cell balance times Trem _n are 0 [minutes], the process proceeds to step S123, and all the battery cells. 104a, 104b,... 104n are set as non-target balance drive target selection results, and in step S129, the balance drive target selection results are stored in the RAM.

On the other hand, if it is determined in step S122 that there is a cell with each cell remaining cell balance time Tremn _n of 0 [minutes], the process proceeds to step S124, and the balance drive target remaining cell balance time maximum value Tremtg_max and the balance stop target remaining are determined. The cell balance time maximum value Tremountg_max is compared. If they do not match, the balance drive target selection result is not updated, and the process ends.
On the other hand, if the comparison between the two matches, or if it is determined in step S121 that it is the time of the first calculation, the process proceeds to step S125, and the balance drive target selection results of all the battery cells 104a, 104b,. Set. However, the cells of each cell remaining cell balance time Trem _n is 0 [min] is set to a non-target.

Next, in step S126, the cell with the largest Trem _n is set as the target among the cells whose balance drive target selection result is not selected, and the process proceeds to step S127.
In step S127, the balance drive target selection result of the adjacent cells set as targets in step S126 is set as non-target, and the process proceeds to step S128.
Next, in step S128, if there remains a cell whose balance drive target selection result is not selected, the process returns to step S126, and steps S126 to S128 are repeated.
On the other hand, if there is no remaining cell whose balance drive target selection result is not selected in step S128, the process proceeds to step S129, and the balance drive target selection result is stored in the RAM.
Note that the processing in step S12 described above is performed by the balance drive target cell selection unit 408.

FIG. 16 is a flowchart showing details of step S13 (balance method selection).
First, in step S131, the balance drive target remaining cell balance time maximum value Tremtg_max is compared with the balance stop target remaining cell balance time maximum value Tremountg_max. If they do not match, the process proceeds to step S133. In step S132, the process proceeds to step S132. In this step S132, it is determined whether or not the target cell matching both is an adjacent cell. If the target cell is an adjacent cell, the process proceeds to step S134, and if not, the process proceeds to step S133. .
In step S133, the balance method selection result is set to the target selection method, and in step S134, the balance method selection result is set to the odd / even cell alternating drive method, and each selection result is stored in the RAM in step S135. To do.
The processing in step S13 is performed by the balance method selection unit 409.

FIG. 17 is a flowchart showing details of step S14 (cell balance drive determination).
First, in step S141, it is determined whether or not the balance method selection result in step S13 is the target selection method. If it is the target selection method, the process proceeds to step S142, and the balance drive target selection result in step S12 is the target. The balancer drive instruction is turned on for the other cells. For the other cells, the balancer drive instruction is turned off.
On the other hand, if the balance method selection result is not the target selection method, the process proceeds to step S143, and the balancer drive instruction for odd and even cells is alternately turned on at a constant cycle. However, the cells each cell remaining cell balance time Trem _n is 0 [min], to turn off the balancer drive instruction unconditionally.

When the balancer driving instruction is turned on in this way, the cell balance switch of the corresponding battery cell is turned on and the balancer 201 is driven.
On the other hand, when the balancer drive instruction is turned off, the cell balance switch of the corresponding battery cell is turned off, and the balancer 201 is stopped.
Note that the process of step S14 is performed by the cell balance drive determination unit 410.

A specific example to which the present invention is applied will be described with reference to FIG.
FIG. 18 shows the transition of the remaining cell balance time Trem during cell balance of the battery pack 104 in which eight battery cells 104a, 104b,... 104n are connected in series (# 1 to # 8).
Note that the remaining cell balance time Trem of each cell at the start of cell balance t10 in FIG. 18 is the same as that in FIG. 19 as the prior art.
Here, the remaining time required for cell balancing of each battery cell 104a, 104b,... 104n to the target cell voltage is Trem, which is the remaining cell balance time Trem calculated in steps S1 to S9. It corresponds to _n .

First, at time t10, a cell to be balanced is selected in step S12. In FIG. 18, according to the control flow of FIG.
Min] is the maximum, cell # 4 is selected as the balance drive target, and cells # 3 and # 5, which are adjacent to cell # 4, are the balance stop targets.
Next, among the cells excluding the cells # 3 to # 5, since the time Trem: 25 [minutes] of the cell # 2 is the maximum, the cell # 2 is selected as a balance driving target and is adjacent to the cell # 2. The cell # 1 is a balance stop target.
Next, among the cells excluding the cells # 1 to # 5, since the time Trem: 15 [minutes] of the cell # 8 is the maximum, the cell # 8 is selected as a balance driving target and is adjacent to the cell # 8. Cell # 7 is a balance stop target.
Further, among the cells excluding the cells # 1 to # 5 and # 7 to # 8, the time Trem: 5 [minutes] of the cell # 6 is the maximum, so the cell # 6 is selected as a target.
The selection of all the cells is completed as described above, and the process of step S12 is ended.

Next, in step S10, the time Trem maximum value of the cell selected as the balance drive target is calculated.
Here, among the cells # 2, # 4, # 6, and # 8 selected in step S12, the time Trem: 30 [min] of the cell # 4 is the maximum, so that the balance target remaining cell balance time maximum value Tremtg_max is 30 [minutes].
Next, in step S11, the time Trem maximum value of the cell selected as the balance stop target is calculated.
Here, since the time Trem: 20 [minutes] of the cell # 1 other than the cells # 2, # 4, # 6, and # 8 selected in step S12 is the maximum, the balance stop target remaining cell balance time maximum value Tremountg_max is 15 [minutes].

Next, in step S13, a balance method is selected.
That is, Tremtg_max and Tremountg_max do not coincide with each other according to the control flow in FIG. 16, and therefore, the balance method selects the target selection method and ends the processing in step S13.

Next, in step S14, cell balance driving determination is performed, the cell balance of the selected cells # 2, # 4, # 6, and # 8 is turned on, and the other cells are turned off.
When the cell balance driving state is continued for 10 minutes in this state, the time Trem of each cell changes to the state of t11.
That is, at time t11, the time Trem of the cells # 2, # 4, and # 8 is decreased by 10 minutes with respect to t10, and the time Trem of the cell # 6 is already 0 minutes. Further, at time t11, in step S10, the balance drive target remaining cell balance time maximum value Tremtg_max is obtained by the time Trem: 20 [minutes] of the cell # 4 having the maximum time Trem among the cells targeted for balance drive in step S10. = 20 [minutes] is calculated.

Furthermore, the balance stop target remaining cell balance time maximum value Tremountg_max = 20 [minutes] is calculated from the time Trem: 20 [minutes] of the cell # 1 having the maximum time Trem among the cells targeted for balance stop in step S11. Is done.
Here, since Tremtg_max and Tremountg_max match and cell # 1 and cell # 4 are not adjacent cells, the balance driving target cell is selected again by the control flow in FIG. As a result, cells # 1, # 4, and # 7 are newly selected as balance drive targets.

Thereafter, cell balance drive determination is performed in step S14, the cell balance of the selected cells # 1, # 4, and # 7 is turned on, and the other cells are turned off. If such a cell balance driving state is continued for 5 minutes, the time Trem of each cell changes to the state indicated by t12.
At this time, in step S10, the balance drive target remaining cell balance time maximum value Tremtg_max = 15 [minutes] by the time Trem: 15 [minutes] of the cell # 1 having the maximum time Trem among the cells targeted for balance drive in step S10. ] Is calculated.
Next, in step S11, the balance stop target remaining cell balance time maximum value Tremountg_max = 15 [minutes] based on the time Trem: 15 [minutes] of the cell # 2 having the maximum time Trem among the cells targeted for balance stop. Is calculated.

  Here, since Tremtg_max and Tremountg_max match and cell # 1 and cell # 2 are adjacent cells, the selection of the balance method is switched to the odd / even cell alternate drive method in step S13, and thereafter the odd and even cells The cell balance driving is alternately performed every predetermined period (1 minute).

Next, at time t12, the odd cells # 1, # 5, and # 7 are turned on, and the other cells are turned off.
Next, at time t13 when the cell balance is continued for one minute, the cell balances of the even cells # 2, # 4, and # 8 are turned on, and the other cells are turned off. At the time t13, the time Trem of the odd-numbered cells # 1, # 5, and # 7 is decreased by 1 minute from the time t12.
Further, at time t14 when the cell balance is continued for 1 minute, the cell balances of even-numbered cells # 1, # 5, and # 7 are turned on, and the other cells are turned off. At the time t14, the time Trem of the even cells # 2, # 4, and # 8 is decreased by 1 minute from the time t13.
Similarly, the cell whose time Trem is 0 minute is turned off, and when the cell balance is alternately performed on the odd and even cells, the time point t15 after 28 minutes from the time point t14. Then, the time Trem of all the cells becomes 0 minutes, and the cell balance is completed.

  Thus, it takes 45 minutes in total from the time point t10 to the time point t15, but the cell balance time is reduced by 15 minutes compared to the prior art shown in FIG. Become.

  As described above, according to the present invention, the entire cell balance time can be determined by selecting the target cell to be preferentially balanced and driving after considering the capacity variation between the battery cells. The advantage that can be shortened is obtained.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the summary, it can change suitably and can be abbreviate | omitted.

100: Electric vehicle 101: Vehicle control device 102: Motor for driving
103: Inverter, 104: Battery pack,
104a, 104b, 104n: battery cells,
105: Battery management device, 106: Battery charger,
107: current detection means 201: balancer 201a: balancer resistance
201b: cell balance switch, 203: battery monitoring IC,
203b: cell voltage detection means 301: microcomputer
302: Cell voltage value storage means, 303: Current value storage means,
304: Each cell capacity estimation means, 306: Cell balance control means,
401: Remaining charge amount calculation means for each cell, 402: Maximum remaining charge amount calculation means,
403: Each cell balancer consumption charge amount calculation means,
404: Each cell balancer consumption current calculation means,
405: Remaining cell balance time calculation unit 406 for each cell: Balance drive target remaining cell balance time maximum value calculation unit,
407: Balance stop target remaining cell balance time maximum value calculating means,
408: Balance drive target cell selection means, 409: Balance method selection means,
410: Cell balance drive determination means

Claims (5)

A cell voltage detecting means for detecting a voltage (V _n ) between terminals in a plurality of battery cells constituting the battery pack;
A balancer connected in parallel with each of the battery cells and controlling a charging current flowing through each of the battery cells;
Current detection means for detecting a charge / discharge current (I) of the battery pack;
Cell remaining charge amount calculating means for calculating a remaining charge amount (Qrem _n ) of each battery cell based on a charge state of the battery pack;
A remaining charge maximum value calculating means for calculating a maximum value (Qrem_max) from the remaining charge amount (Qrem _n ) of each battery cell;
From the remaining charge amount (Qrem _n ) calculated by the cell remaining charge amount calculating means and the remaining charge amount maximum value calculating means and the remaining charge amount maximum value (Qrem_max) until the battery cells are fully charged. Each cell balancer consumption charge amount calculating means for calculating a charge amount (Qc _n ) that needs to be consumed by the balancer;
The balancer is a unit based on the inter-terminal voltage (V _n ) detected by the cell voltage detection means, the charge / discharge current (I) detected by the current detection means, the internal resistance of each battery cell, and the resistance of the balancer. Each cell balancer consumption current calculation means for calculating a balancer consumption current (Ib _n ) consumed per time;
A cell balance until each battery cell is fully charged from the charge amount (Qc _n ) and the balancer consumption current (Ib _n ) calculated by each cell balancer consumption charge calculation means and each cell balancer consumption current calculation means Each cell remaining cell balance time calculating means for calculating the time (Trem _n ) required for
The cell having the maximum time (Trem _n ) required for the cell balance of each battery cell is selected as a balancer drive target cell, and both neighbors of the balancer drive target cell are selected as balancer stop target cells, and further the balancer drive In a target cell or a cell that is not determined as a balancer stop target cell, a cell having the maximum time required for cell balance (Trem _n ) is set as a balancer drive target cell, and both sides of the balancer drive target cell are stopped in balancer Selecting as a target cell, and equipped with balance drive target cell selection means for selecting a balancer drive target cell or a balancer stop target cell until all cells become balancer drive target cells or balancer stop target cells,
The battery management device, wherein the balancer is driven and controlled by an output of the balance driving target cell selecting means. The battery management device according to claim 1,
Balance driving target cell remaining cell balance time maximum value calculating means for calculating a remaining cell balance time maximum value (Tremtg_max) in the balancer driving target cell based on the output of each cell remaining cell balance time calculating means, and a balancer stop target A balance stop target cell remaining cell balance time maximum value calculating means for calculating a remaining cell balance time maximum value (Tremountg_max) in the cell;
The cell balance control is continued until the maximum remaining cell balance time (Tremtg_max) in the balancer driving target cell matches the maximum remaining cell balance time (Tremuntg_max) in the balancer stop target cell. A battery management device. The battery management device according to claim 1,
When the remaining cell balance time maximum value (Tremtg_max) in the balancer driving target cell and the remaining cell balance time maximum value (Tremuntg_max) in the balancer stop target cell match, the remaining cells in the balancer driving target cell If the cell having the maximum balance time (Tremtg_max) and the cell having the maximum remaining cell balance time (Tremuntg_max) in the balancer stop target cell are not adjacent to each other, the balance driving target cell selecting unit is operated again. A battery management apparatus characterized in that a balancer drive target cell is selected. The battery management device according to claim 1,
Based on the maximum remaining cell balance time (Tremtg_max) in the balancer driving target cell and the maximum remaining cell balance time (Tremuntg_max) in the balancer stopped target cell, the cell selected as the balancer driving target cell A battery management apparatus comprising a balance method selection means for selecting a balance method for performing cell balance or alternately performing cell balance for odd-numbered and even-numbered cells every predetermined period. The battery management device according to claim 4,
The balance method selection means, when the remaining cell balance time maximum value (Tremtg_max) in the balancer driving target cell and the remaining cell balance time maximum value (Tremuntg_max) in the balancer stop target cell match, If the cell having the maximum remaining cell balance time (Tremtg_max) in the driving target cell and the cell having the maximum remaining cell balance time (Tremuntg_max) in the balancer stop target cell are adjacent to each other, the odd / even A battery management device characterized in that cells are switched to a method in which cells are alternately balanced.

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