JP2004015924A - Battery pack control device and control system - Google Patents

Abstract

Provided is an assembled battery control device capable of maintaining a voltage of an assembled battery within a certain range regardless of a load state.
A plurality of cells C1, C2, C3 connected in series can be separated from a series connection, which is a high-power line, by switches S1a to S3a, S1b to S3b. For example, when the switch S1b is opened and the switch S1a is closed, the cell C1 is disconnected. When the switch S1a is opened and the switch S1b is closed, the disconnected cell C1 is connected again. The CPU 102 controls the opening and closing of the switches S1a to S3a and S1b to S3b by changing the number of cells connected in series according to the assembled battery voltage and the charging / discharging current so that the assembled battery voltage falls within a predetermined voltage range.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an assembled battery control device for an assembled battery including a plurality of cells, and a control system including the assembled battery control device to control the output of a load.
[0002]
[Prior art]
2. Description of the Related Art As a power supply device for supplying power to a driving motor of an electric vehicle or the like, a power supply device in which a number of batteries are connected in series to obtain a predetermined voltage is used. In this type of power supply device, the necessity of battery charging is checked by monitoring the output terminal voltage of the power supply device. For example, if the internal resistance of one of the batteries is higher than a predetermined value and the battery is overdischarged, a warning is issued that charging is necessary. In such a case, the driver performs the charging operation of the power supply device according to the warning even though the vehicle can actually run.
[0003]
Therefore, a power supply device for preventing such unnecessary charging is disclosed in JP-A-7-163059. In the power supply device, the above-described problem is prevented from occurring by disconnecting the battery whose internal resistance is equal to or more than the predetermined value from the power supply device.
[0004]
[Problems to be solved by the invention]
However, in the power supply device disclosed in Japanese Patent Application Laid-Open No. 7-163059, the battery whose internal resistance is equal to or more than a predetermined value is separated, so that the full charge voltage of the assembled battery decreases after the separation. Become. Therefore, there is a possibility that the load cannot be operated at a predetermined constant voltage.
[0005]
An object of the present invention is to provide a battery pack control device capable of maintaining the voltage of a battery pack within a certain range irrespective of a load state, and a control system including the battery pack control device to control the output of a load. To provide.
[0006]
[Means for Solving the Problems]
The present invention relates to a battery pack control device used for a battery pack in which a plurality of cells are connected in series. Each cell connected in series can be disconnected from the series connection which is a high-power line by the connection switching means. Further, the disconnected cells can be connected again in series by the connection switching means. The disconnection / connection operation by the connection switching means is controlled by the control means. The control means changes the number of cells connected in series according to the battery state of the battery pack so that the voltage of the battery pack falls within a predetermined voltage range.
[0007]
【The invention's effect】
According to the present invention, since the number of cells connected in series can be changed according to the battery state of the battery pack, the voltage of the battery pack is maintained within a certain range regardless of the state of the load connected to the battery pack. be able to.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a drive control system of a hybrid electric vehicle (HEV), and includes a battery pack control device according to the present invention. The drive control system shown in FIG. 1 shows a drive control system of the HEV. The rotor of the electric motor 2 is directly connected to the main shaft of the engine 1. The driving force of the engine 1 and / or the motor 2 is transmitted to the axle via the transmission 3 to rotate the wheels 4.
[0009]
The HEV basically runs on the engine 1 and assists the driving force by operating the motor 2 when starting, accelerating, or climbing a hill where the load on the engine 1 increases. The electric power of the motor 2 is supplied from an assembled battery 5 which is a driving battery. DC power from the battery pack 5 is converted into AC power by the inverter 6 and supplied to the motor 2.
[0010]
On the other hand, when the efficiency of the engine 1 is low and the load is light, the motor 2 is operated as a generator to charge the battery pack 5, thereby reducing the load fluctuation of the engine 1 and increasing the energy efficiency. Further, at the time of braking or downhill, the running energy is converted into electric energy by regenerative braking, and the battery pack 2 is regeneratively charged. When the vehicle is stopped, the engine 1 is stopped and idle stop is performed. When charging the battery pack 5 using the motor 2 as a generator, the inverter 6 converts AC power from the motor 2 into DC power and supplies the DC power to the battery pack 5.
[0011]
The battery control controller 7 manages and controls the assembled battery 5. For example, the battery state is determined based on the open voltage, the internal resistance, the battery charge state, and the like, and control described later is performed according to the battery state. The vehicle controller 8 calculates the required driving force of the vehicle based on the accelerator operation amount detected by the accelerator sensor 9, the brake operation amount detected by the brake sensor 10, the vehicle speed information from the vehicle speed sensor 11, and the like. Further, the vehicle controller 8 calculates a motor torque and an engine torque required to achieve the calculated required driving force. A current command value based on the motor torque information is sent to the inverter 6. Power for the battery controller 7 and the vehicle controller 8 is supplied from the auxiliary battery 12. The turning on and off of the power is controlled by a switch 13 that opens and closes in conjunction with the turning on and off of an ignition switch 14. As the auxiliary battery 12, for example, a 12-volt battery is used.
[0012]
FIG. 2 is a diagram illustrating the battery controller 7. The battery pack 5 of the present embodiment includes twelve cells Cx (x = 1, 2,..., 12), and these cells Cx are connected in series. FIG. 2 shows some of the cells C1 to C3 in the 12 cells. The voltage of each cell Cx is detected by the cell voltage detection circuit 101. The switches S1a, S1b, and S1c are open / close switches for disconnecting the cell C1 from the series connection of the battery pack 5 (high-voltage line) and adjusting the capacity of the cell C1. Similarly, switches S2a, S2b, and S2c are provided for the cell C2, and switches S3a, S3b, and S3c are provided for the cell C3. For example, when disconnecting the cell C1 from the high-voltage line, the switch S1a is closed and the switch S1b is opened. When adjusting the capacity of the cell C1, the switch S1a is opened and the switches S1b and S1c are closed.
[0013]
The CPU 102 controls opening and closing of the switches S1a to S1c, S2a to S2c, and S3a to S3c based on each cell voltage detected by the cell voltage detection circuit 101. The memory 103 stores the cell voltage detected by the current sensor 104 and various calculation results calculated by the CPU 102, and also stores data necessary for the calculation in advance. The resistor R is a resistor for adjusting the capacitance. Switches S1a, S2a, S3a are connected to control port PA of CPU 102, switches S1b, S2b, S3b are connected to control port PB, and switches S1c, S2c, S3c are connected to control port PC. The current sensor 104 detects a current value of a current flowing through the battery pack, and transmits the detection data to the CPU 102.
[0014]
《Explanation of control operation》
Next, separation control will be described with reference to a flowchart. 3 and 4 are flowcharts showing the processing procedure of a program executed by the CPU 102 of the battery control controller 7, and FIG. 4 shows the processing subsequent to FIG. In the following description, it is assumed that the battery pack 5 is provided with 12 cells, and the basic setting of the number of connected cells is 11. The number of connections at the start of the process in FIG. 3 is 11, and 11 is stored in the memory 103 as the number of connected cells. Regarding cell separation, three types are selected from (1) when the number of separated cells is zero, (2) when the number of separated cells is 1, and (3) when the number of separated cells is 2.
[0015]
The process in FIG. 3 is started by turning on the ignition switch 14. In step S10, the cell voltage of each cell Cx is detected by the cell voltage detection circuit 101. In the following step S20, the charge / discharge current value of the battery pack 5 is detected by the current sensor 104. Note that, in the present embodiment, the sign of the current value is plus in the case of discharging, and the sign of the current value is minus in the case of charging. In step S30, it is determined whether the ignition switch 14 is on, that is, whether the vehicle is being started. If it is determined to be on in step S30, the process proceeds to step S40, and if it is determined to be off, a series of processing ends.
[0016]
In step S40, it is determined whether or not the variable M is M = 0. The default value of the variable M is zero. Even if the variable M is replaced with a numerical value other than zero after the ING is turned on, the variable M is returned to the default state when the ignition switch 14 is turned off. If M = 0 is determined in step S40, the process proceeds to step S300 to set M = 1, and then proceeds to step S210 in FIG. On the other hand, if M ≠ 0 is determined in step S40, the process proceeds to step S50. In step S50, a total voltage (= assembled battery voltage) is obtained by adding the cell voltages detected in step S20.
[0017]
In step S60, the number of connected cells is selected using the charge / discharge current value detected in step S20, the total voltage obtained in step S50, and the map shown in FIG. The map in FIG. 5 shows the relationship between the battery state of the battery pack 5 and the number of connected cells. The battery state is represented by the total voltage of the assembled battery 5 (= assembled battery voltage) and the charge / discharge state. When the battery state is included in any of the areas A1, A3, and A5 in FIG. 5, the number of connected cells is 11 which is the basic number of connected cells. When the battery state is included in the area A2, the number of connected cells is set to 10, which is one less than the number of basic connections. When the battery state is included in any of the regions A4, A6, and A7, the number of connected cells is set to 12 which is one more than the basic number of connected cells.
[0018]
As long as the battery state remains in one area, the number of connected cells remains constant. On the other hand, when the battery state changes beyond the area, the number of connected cells is changed according to each area. Of course, when the battery state changes between the regions having the same number of connection cells in FIG. 5, the number of connection cells does not change. In the present embodiment, the range of the total voltage of 39 V to 45 V is the practical voltage range of the battery pack 5, and this range, that is, the areas A2 to A4 will be referred to as normal areas related to the total voltage. Also, the battery pack 5 tends to be overcharged in the area A1 where the total voltage is 45 V or more, and tends to be overdischarged in the areas A5 to A7 where the total voltage is 39 V or less.
[0019]
In step S70, the number of connected cells stored in the memory 103 is read. In step S80, the number of connected cells stored in the memory 103 is replaced with the number of connected cells selected in step S60. In the present embodiment, 11 is stored as the initial state. For example, if 12 is selected as the number of connected cells in step S60, the number of connected cells in the memory 103 is changed from 11 to 12. Even when the number of selected connection cells is 11 and the size does not change, the number of connection cells stored in the memory 103 is replaced.
[0020]
In step S90, the number of connected cells read from the memory 103 in step S70 is compared with the number of connected cells selected in step S60 and stored in the memory 103 in step S80, and the following determination is made. That is, the change form before and after the replacement of the number of connected cells in the memory 103 is “no change”, “change from 12 to 11”, “change from 11 to 10”, “change from 10 to 11”, and “change from 11 to 12”. "Change". As described above, the number of disconnected cells is either 0, 1, or 2. Therefore, if the number of connected cells is changed one by one, the number of connected cells changes in the above five types. If it is determined in step S90 that the change mode of the number of connected cells is “no change”, the process proceeds to step S210 in FIG.
[0021]
If it is determined in step S90 that the change form of the number of connected cells is “12 → 11”, that is, the battery state (the voltage of the battery pack 5 and the charge / discharge current) is the state of the regions A4, A6, and A7 in FIG. When the state changes from A to A1, A3, and A5, the process proceeds to step S100 to execute connection switching processing 1. Similarly, when the change mode is determined to be “11 → 10”, the process proceeds to step S110 to execute the connection switching process 2, and when the change mode is determined to be “10 → 11”, the process proceeds to step S120 to perform the connection switching process. Execute 3. If the change mode is determined to be “11 → 12” in step S90, the process proceeds to step S130 to close the switch Sxb for the cell Cx in the non-connected state and open the switches Sxa and Sxc to set the non-connected state. The connected cell Cx is connected to the high-power line.
[0022]
(Detailed description of connection switching processing 1)
FIG. 6 is a flowchart showing the procedure of the connection switching process 1 in step S100. In step S41, the voltage of each cell Cx is detected by the cell voltage detection circuit 101. In step S42, one having the minimum cell voltage is specified from the cell voltages detected in step S41. In step S43, the minimum cell voltage specified in step S42 is stored in the memory 103 together with the sign of the cell Cx. In step S44, the switch Sxa for the cell Cx specified in step S43 is closed, and the switches Sxb and Sxc are open. As a result, the cell Cx is disconnected from the high-voltage line (= series connection).
[0023]
For example, consider the case where the battery state changes from the area A4 to the area A1 in a discharge state at a large current (50 A or more) as indicated by an arrow (1) shown in the map of FIG. In this case, the total voltage of the battery pack 5 becomes larger than the normal range (39 V to 45 V). Therefore, in such a situation, as described above, the number of connected cells is reduced from 12 to 11 by one. As a result, the amount of discharge per cell increases, and the assembled battery voltage that tends to change in the overcharge direction can be changed to the normal region side. That is, the cell separation acts to return the battery pack voltage to the normal range, and the battery pack voltage is kept constant.
[0024]
Also, when the battery state changes from the area A6 to the area A3 due to charging as shown by the arrow (14), the number of connected cells is reduced by 1 from 12 to 11. In this case, since the battery pack voltage is in the normal range from the overdischarge tendency (39 V or less), the number of connected cells is returned to the basic 11 cells.
[0025]
As shown by an arrow (2) in FIG. 7, when the battery pack voltage changes from a discharge at a large current to a charge / discharge state by a normal current (−50 A to 50 A) while maintaining a state of a normal region (39 V to 45 V). Also, the number of connected cells is returned from 12 to the basic number of connections 11. Since the cell Cx is considered to deteriorate as it is used, the deterioration of the separated cell Cx is suppressed. In addition, since the vehicle is in a discharged state except during regeneration when the vehicle is running, the discharged state continues in the region A3. In this case, by disconnecting the cell having the lowest cell voltage, the cell can be prevented from being over-discharged.
[0026]
The change of the arrow (3) in FIG. 7 is a case where the battery is shifted from normal charging and discharging to a charging state of a large current (magnitude of 50 A or more) in a state where the battery pack voltage tends to be overdischarged lower than the normal region. In this case, the battery pack voltage changes to the normal range due to the continuation of charging, so the number of connected cells is returned to 11. Of course, charging may be performed with 12 cells, but when 11 cells are used, the assembled battery voltage easily returns to the normal region more quickly. Also, since an increase in the number of times of charging and discharging promotes cell deterioration, it is better to reduce the number of cells to 11 cells rather than keeping 12 cells from the viewpoint of deterioration.
[0027]
The change of the arrow (13) in FIG. 7 is a case where the state is changed from a state of discharging with a large current (50 A or more) in the overdischarge tendency to a normal charge and discharge state. The assembled battery voltage increases by charging and changes to a normal region. In the area A3, normal charge / discharge is performed at the battery pack voltage in the normal area, so the number of connected cells is returned from 12 cells to the basic 11 cells.
[0028]
According to the above connection switching process 1, by reducing the number of connected cells by 1 from 12 to 11, the assembled battery voltage that tends to change in the overcharge direction is changed to the normal region side. Thus, the assembled battery voltage can be kept constant. In addition, in the case of a change as indicated by the arrow (2), the cell having the lowest cell voltage is cut off to prevent the cell from being over-discharged.
[0029]
(Detailed description of connection switching process 2)
FIG. 8 is a flowchart showing the procedure of the connection switching process 2 in step S110. The connection switching process 2 is executed when the charging / discharging state with a small current changes from the charging / discharging state with a large current as shown by an arrow (4) in FIG. 9 or the battery pack as shown by an arrow (5). This is the case where the voltage changes from the overdischarge tendency to the normal region. In such a case, two cells Cx are separated to make the number of connected cells 10 cells. In the present embodiment, the two cells having the higher cell voltage are separated as described below.
[0030]
In step S51 of FIG. 8, the cell voltages of the 11 connected cells are detected by the cell voltage detection circuit 101, respectively. In step S52, two of the cell voltages detected in step S51 are specified in descending order of voltage. In step S53, the two cell voltages specified in step S52 are stored in the memory 103 together with the codes of the corresponding cells Cx. In step S54, the switch Sxa for each cell Cx specified in step S53 is closed, and the switches Sxb and Sxc are open. At the same time, the switch Sxb of the cell Cx, which has been disconnected, is closed, and the switches Sxa, Sxc are opened. That is, two cells having a higher cell voltage out of the 11 connected cells are disconnected, and the cells that have been disconnected until now are connected.
[0031]
The reason for performing the connection switching operation as in step S54 is that, when cells are disconnected and connected one by one, there is always a high possibility that the same cell will be disconnected and connected, and the deterioration of a specific cell will progress. There is a possibility that it will be. On the other hand, when the number of connected cells is reduced by 1, if two cells are separated and one cell in a non-connected state is connected as described above, the bias of cells to be disconnected / connected is suppressed, Cell degradation can be made uniform.
[0032]
In the change as indicated by the arrow (4) shown in the map of FIG. 9, when the battery pack voltage is in the normal region, the state where the normal (−50 A to 50 A) charge / discharge is performed is changed to a large current (current value). The state shifts to a charged state when the size is 50 A or more). In this case, since the battery pack voltage tends to increase due to charging, the number of connected cells is reduced from 11 to 10 so that the battery pack voltage is maintained in the normal range (39 V to 45 V). Further, when the cell is separated, the cell with the higher cell voltage is separated, so that the cell with the higher cell voltage can be prevented from being overcharged. Also in this case, the separated cells are prevented from being deteriorated due to repeated charging and discharging.
[0033]
The change as indicated by the arrow (5) in FIG. 9 corresponds to the case where the assembled battery voltage shifts from the overdischarge tendency to the normal region in the large charge current state. In this case, the number of connected cells is reduced from 12 to 11, so that the assembled battery voltage does not tend to be overcharged by charging.
[0034]
According to the connection switching process 2 as described above, by reducing the number of connected cells by 1 from 11 to 10, the change of the battery pack voltage to the overcharge tendency is suppressed, and the battery pack voltage is kept constant. Can be kept. Further, by disconnecting two cells having a high cell voltage and connecting cells in a non-connected state, bias of cells to be disconnected / connected can be suppressed, and cell deterioration can be made uniform. In the example described above, two cells are separated in order from the cell having the highest cell voltage. However, two cells having a cell voltage equal to or higher than a predetermined cell voltage may be selected and separated.
[0035]
(Detailed Description of Connection Switching Process 3)
FIG. 10 is a flowchart showing the procedure of the connection switching process 3 in step S120. The connection switching process 3 is executed when the total voltage decreases from the normal region to the overdischarge tendency in the charging state with a large current as indicated by an arrow (6) in FIG. 11 or as indicated by an arrow (7). The case where the total voltage changes from a large current charge to a small current charge / discharge state in the normal region. In such a case, the higher voltage cell of the two cells in the non-connected state is switched to the connected state.
[0036]
In step S61 of FIG. 10, the cell voltage of the non-connected state cell stored in the memory 103 is read. This cell voltage is the voltage data stored in step S51 of FIG. In step S62, which of the read cell voltages is higher is specified. In step S63, the switch Sxb for the cell Cx specified in step S62 is closed, and the switches Sxa and Sxc are open. As a result, the cell Cx is connected to the high-power line.
[0037]
According to the above connection switching process 3, the battery pack voltage can be kept constant by increasing the number of connected cells. For example, when the battery pack voltage changes from the normal range to the overdischarge tendency as indicated by the arrow (6) in the map of FIG. 11, the battery pack voltage is increased by increasing the number of connected cells from 10 to 11. So that Also, as shown by the arrow (7), when the state of charge changes from a state of charge due to a large current to a state of normal discharge, overdischarge tends to occur. By increasing the number of connected cells, overdischarge can be prevented. Further, by returning the number of connected cells to the basic number 11, the cell degradation can be equalized (the load can be equalized).
[0038]
In the map of FIG. 11, arrows (8) to (12) indicate the case where the number of connected cells changes from 11 to 12. In the case of the change as indicated by the arrow (8), the battery pack voltage changes from the normal area to the overdischarge tendency in the normal charge / discharge state, so the number of connected cells is increased from 11 to 12 and the battery pack voltage is increased. Increase. In the change as indicated by the arrow (9), the state of charge is changed from a large current charge state to a normal charge / discharge state in the overdischarge tendency state. To increase.
[0039]
When the change is indicated by arrows (10) and (11), the battery voltage of the battery pack tends to change to the overdischarge side due to the discharge due to the large current. Increase the battery pack voltage in the normal range. When the battery is discharged with a large current as shown by the arrow (12) and the battery state changes from the region A1 to the region A4, the battery voltage tends to decrease due to the discharge. The number of connected cells is increased from 11 to 12 so as not to cause overdischarge. As a result, the assembled battery voltage is kept in the normal range.
[0040]
Returning to FIG. 3, when any of the processes in steps S100 to S130 is completed, the process proceeds to step S140 to detect the voltage of each cell after connection switching. In step S150, the total voltage is calculated based on the cell voltage detected in step S140. When the process in step S150 ends, the process proceeds to step S160 in FIG.
[0041]
In step S160 in FIG. 4, based on the current number of connected cells and the total voltage calculated in step S150, and the number of connected cells−limit voltage value table shown in FIG. Is determined. In the present embodiment, the upper limit value and the lower limit value of the voltage of a single cell are 4.25 V and 2.00 V, and the limit voltage value of the battery pack 5 varies depending on the number of connected cells. In the example shown in FIG. 12, the upper limit value of the battery pack limit voltage value is set as “(limit voltage upper limit value) <(single cell upper limit value) × (number of connected cells)”. Further, the lower limit value of the assembled battery limit voltage value is set as “(lower limit value of single cell) × (number of connected cells) <(lower limit value of limit voltage)”.
[0042]
In step S160, for example, when the number of connected cells is 10, if the total voltage is 42.0V to 22.0V, it is determined that the restriction is not necessary (No), and the process proceeds to step S210. On the other hand, if the number of connected cells is 10 and the total voltage is 42.0 V or more, or if the total voltage is 22.0 V or less, it is determined that restriction is necessary (YES), and the process proceeds to step S170. In step S170, a counter n indicating the limit number is incremented. In step S180, it is determined whether or not the counter n has become 3 or more. When it is determined that n ≧ 3, the process proceeds to step S190, and when it is determined that n <3, the process proceeds to step S200.
[0043]
If it is determined that n ≧ 3 and the process proceeds from step S180 to step S190, there is a high possibility that an abnormality has occurred in the battery pack 5 or the cell voltage detection circuit 101. Therefore, in step S190, a control signal requesting a stop of the vehicle or the like is transmitted to the vehicle controller 8 of FIG. Upon receiving this control signal, the vehicle control controller 8 issues a warning using an indicator or a buzzer (not shown) and stops the vehicle.
[0044]
If it is determined in step S180 that n <3 and the process proceeds to step S200, the limiting value for limiting the magnitude of the output value or the regenerative value is transmitted to the vehicle control controller 8. For example, when n = 1, the limiting rate is 10%, and when n = 2, the limiting rate is 20%. The vehicle controller 8 having received the limit rate limits the motor torque calculated based on the various sensor information according to the limit rate. For example, when the limiting ratio is 10%, the control is performed so that the output is 90% with respect to the calculated motor torque.
[0045]
In step S210, the cell voltage detection circuit 101 detects the voltage of each cell. In step S220, an average value of the cell voltages is calculated based on the cell voltages detected in step S210. In step S230, a difference between the cell voltage average value calculated in step S220 and each cell voltage detected in step S210 is calculated, and a cell requiring capacity adjustment is specified.
[0046]
In step S240, the switch Sxc relating to the cell Cx for which the capacity adjustment is specified in step S230 is closed (ON). As a result, the capacity is adjusted by discharging with the capacity adjusting resistor R. By performing such a capacity adjustment operation, it is possible to reduce the variation in the charge capacity of each cell and to prevent an extreme difference in the degree of deterioration of each cell from occurring. Upon completion of the process in the step S240, the process returns to the step S10 in FIG.
[0047]
In the embodiment described above, the total number of cells provided in the battery pack 5 is 12 cells, the basic setting of the number of connected cells is 11, and the number of cells to be disconnected is two. The numbers are not limited to these. Also, an example of the connection switching process in steps S110 to S120 is shown, and the connection switching process is not limited to the above-described process as long as the connection switching process keeps the voltage of the battery pack 5 within a predetermined range.
[0048]
In the correspondence between the embodiment described above and the elements of the claims, switches S1a to S3a and S1b to S3b are connection switching units, CPU 102 is a control unit and a charge state detection unit, and cell voltage detection circuit 101 is a cell voltage detection circuit. The voltage detection means, the resistance R constitutes a capacity adjustment means, and the vehicle controller 8 constitutes a restriction means. In addition, the range of the battery pack voltage of 39 V to 45 V in FIG. 5 corresponds to the predetermined voltage range, and the range of the current value from −50 A to 50 A corresponds to the predetermined current range. Further, the assembled battery limit voltage value in FIG. 12 corresponds to the threshold value. The present invention is not limited to the above-described embodiments as long as the above-described characteristic functions and effects can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a battery pack control device according to the present invention, and shows a schematic configuration of a drive control system of a hybrid electric vehicle (HEV).
FIG. 2 is a diagram illustrating a battery control controller 7;
FIG. 3 is a flowchart showing a processing procedure of a program executed by a CPU 102 of a battery control controller 7;
FIG. 4 is a flowchart showing processing subsequent to FIG. 3;
FIG. 5 is a diagram showing the relationship between the battery state of the battery pack 5 and the number of connected cells.
FIG. 6 is a flowchart showing a detailed procedure of connection switching processing 1;
FIG. 7 is a diagram showing types of battery state changes in connection switching processing 1.
FIG. 8 is a flowchart showing a detailed procedure of connection switching processing 2;
FIG. 9 is a diagram showing types of changes in the battery state in connection switching processing 2.
FIG. 10 is a flowchart showing a detailed procedure of connection switching processing 3;
FIG. 11 is a diagram showing types of changes in the battery state in connection switching processing 3.
FIG. 12 is a diagram showing a relationship between the number of connected cells and a limit voltage value.
[Explanation of symbols]
1 engine
2 motor
5 battery pack
6 Inverter
7 Battery control controller
8 Vehicle controller
101 Cell voltage detection circuit
102 CPU
103 memory
104 current sensor
R Capacitance adjustment resistor
S1a to S3a, S1b to S3b, S1c to S3c switches

Claims (11)

A battery pack control device for a battery pack in which a plurality of cells are connected in series,
Connection switching means for disconnecting the cell from the series connection, and connecting the disconnected cell to the series connection for each cell;
Control means for controlling the connection switching means according to the battery state of the battery pack, and changing the number of serially connected cells so that the voltage of the battery pack falls within a predetermined voltage range. Battery control device. The battery pack control device according to claim 1,
The battery pack control device according to claim 1, wherein the battery state is a state based on a voltage and a charge / discharge current of the battery pack, and the number of series connections is changed according to the voltage and the charge / discharge current of the battery pack. The battery pack control device according to claim 2,
Cell voltage detecting means for detecting a cell voltage of each of the cells connected in series,
The control means changes from a large current discharge state in which a discharge current is equal to or greater than a predetermined current range to a normal discharge state in the predetermined current range, and when the voltage of the battery pack reaches the predetermined voltage range, at least the A battery pack control device that controls so as to disconnect the cell having the lowest cell voltage detected by the cell voltage detection means from the series connection. The battery pack control device according to claim 2,
Cell voltage detecting means for detecting a cell voltage of each of the cells connected in series,
When the charge / discharge current changes from a normal charge / discharge state, which is a predetermined current range, to a large current charge state, which is equal to or less than the predetermined current range, the cell voltage detected by the cell voltage detection means is changed to a predetermined value. Disconnecting at least two or more cells from the series connection, and controlling so that cells that are disconnected and not connected are connected by a number smaller than the number of cells disconnected from the series connection. Battery control device to do. The battery pack control device according to claim 4,
The control unit is configured to control the cell voltage detected by the cell voltage detection unit to be a predetermined value even when the voltage of the battery pack changes from a state equal to or lower than the predetermined voltage range to within the predetermined voltage range in the large current charging state. At least two or more cells having a value or more are disconnected from the series connection, and the cells in the disconnected and unconnected state are controlled so as to be connected by a number smaller than the number of cells disconnected from the series connection. Battery controller. The battery pack control device according to claim 2,
Cell voltage detecting means for detecting a cell voltage of each of the cells,
When the charge / discharge current changes from a large current charge state in which the charge / discharge current is equal to or lower than a predetermined current range to a normal charge / discharge state in the predetermined current range, the cell having the highest cell voltage among the cells in the non-connected state. A battery pack control device, which controls the battery pack to be connected. The battery pack control device according to claim 6,
In the high current charging state, the control unit may also be configured such that, even when the voltage of the battery pack changes from the predetermined voltage range to a state equal to or lower than the predetermined voltage range, the cell voltage among the cells in the non-connected state is the highest. An assembled battery control device that controls so as to connect high cells. The assembled battery control device according to any one of claims 1 to 7,
A battery pack control device comprising: a capacity adjusting unit that adjusts a charge amount of each of the cells according to a cell voltage of each of the cells so that a cell voltage distribution range of the plurality of cells is narrowed. The battery pack control device according to claim 8,
The battery pack control device, wherein the capacity adjustment by the capacity adjustment unit is performed after the control unit changes the number of series connections. An assembled battery control device according to any one of claims 1 to 9,
Charge state detection means for detecting an overdischarge state or an overcharge state according to the voltage of the battery pack,
Control means for limiting the output of a load to which power is supplied from the battery pack according to the state of charge detected by the charge state detection means, and controlling the load driven by the battery pack. system. In the control system according to claim 10,
The control system according to claim 1, wherein said state-of-charge detecting means changes a threshold value for detecting said over-discharge state and said state of over-charge according to the number of cells in said series connection state.

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