JP5507289B2 - Battery control system - Google Patents

Description

  The present invention relates to a battery control system.

In an assembled battery (battery) in which a plurality of secondary batteries (unit cells or cells) are connected in series, a bypass resistor is connected in parallel to each unit cell to perform bypass discharge, and the state of charge of each unit cell is aligned. That is, a battery device that performs cell balance (variation correction) is known (see, for example, Patent Document 1).
In this device, in an assembled battery in which four unit cells are connected in series, a series body of a bypass resistor and a switching element is connected in parallel to each unit cell, and a differential amplifier is connected to each unit cell. The output of the amplifier is connected to the microcomputer via a multiplexer and an A / D converter. Then, the open voltage of each unit cell is detected to calculate the remaining capacity of each unit cell, and the switching elements of the unit cells other than the unit cell that exhibits the minimum remaining capacity are closed and discharged through the bypass resistor. ing.

JP 2000-092732 A

  However, in the conventional battery device described above, since the bypass resistors of all the single cells that perform bypass discharge generate heat, it is difficult to take measures against heat dissipation, and the bypass discharge circuit section becomes large and has difficulty in incorporation into the battery device. .

The battery control system according to the present invention includes a battery control system that corrects variation in a charging state between the secondary batteries in an assembled battery in which a plurality of secondary batteries are connected in series. A determination circuit for determining whether or not each secondary battery needs to be discharged based on a charge state of the secondary battery detected by the charge state detection circuit; A constant current circuit for supplying a constant current to the battery, a switching circuit for switching the circuit to pass the constant current of the constant current circuit to one or a plurality of the secondary batteries, and the determination circuit determining that the discharge is necessary and a control circuit for switching the circuit by the switching circuit so that the constant current of the constant current circuit to the secondary battery through the control circuit, by the determination circuit A predetermined procedure in response to the position and number of the secondary battery in the determined the battery pack and Den'yo, be carried out in stages and the switching of the current value of the switching between the constant current circuit of the circuit according to the switching circuit It is characterized by.

  According to the present invention, instead of the heat generated by the conventional bypass discharge resistor, the heat generated by the transistor of the constant current circuit is replaced, and the heat dissipation process can be easily performed by using a heat dissipation member such as a heat sink. And by disposing the constant current circuit as a heat source separately from the cell controller, it becomes possible to exclude the heat radiator from the cell controller, and it becomes possible to store the cell controller in one IC package. Thus, the device can be reduced in size, and the battery control system can be easily manufactured and incorporated in the battery device.

The figure which shows the outline | summary of the bypass discharge circuit part of one embodiment The figure which shows the switching method of the electric current value of the switches 31-34 and the constant current circuits 21 and 22 in the case of bypass discharge of any one of the four unit cells 11-14 which comprise the assembled battery 10. The figure which shows the switching method of the electric current value of the switches 31-34 and the constant current circuits 21 and 22 at the time of carrying out the bypass discharge of the cell 11 and 13 The figure which shows the switching method of the electric current value of the switches 31-34 and the constant current circuits 21 and 22 in the case of carrying out the bypass discharge of the three unit cells 11, 13, and 14 1 is a block diagram showing the overall configuration of a battery control system according to an embodiment mounted on an electric vehicle Circuit diagram showing one embodiment of the switch circuit 30 Circuit diagram showing an embodiment of the constant current circuit 21 Circuit diagram showing one embodiment of the constant current circuit 22 A circuit diagram showing an embodiment of a voltage detection circuit 50 and a multiplexer 60 and a control circuit 70 The flowchart which shows the cell balance (variation correction of charge capacity) control of one embodiment The figure which shows an example of the distribution frequency of the open circuit voltage OCV of a several cell The figure which shows the structure of the modification which applied the cell controller 100 of one Embodiment to 10A of batteries (assembled battery) which connected eight unit cells 11-18 in series. The figure which shows the structure of the other modification which applied the cell controller 100 of one Embodiment to 10A of batteries (assembled battery) which connected eight unit cells 11-18 in series.

  First, the configuration and operation of the bypass discharge circuit unit in the battery control system of the embodiment will be described. FIG. 1 is a diagram illustrating an outline of a bypass discharge circuit unit according to an embodiment. Here, an explanation will be given by taking as an example an assembled battery (hereinafter also referred to as a battery) 10 in which four secondary batteries (hereinafter referred to as single cells or cells) 11 to 14 are connected in series. The number is not limited to four.

  The bypass discharge circuit unit according to the embodiment includes two constant current circuits 21 and 22, four switches 31 to 34, and a selection circuit 40. The constant current circuits 21 and 22 are circuits that cause a constant current to flow through one or a plurality of single cells that need to be discharged among the single cells 11 to 14 and discharge the electric charges charged in those single cells. . The constant current circuit 21 connected to the positive electrode side of the assembled battery 10 is connected in a direction in which current flows from the positive electrode side of the assembled battery 10 to any of the cells 11 to 14 via any of the switches 31 to 34. . On the other hand, the constant current circuit 22 connected to the negative electrode side of the assembled battery 10 is connected in a direction in which a current flows from one of the cells 11 to 14 to the negative electrode side of the assembled battery 10 via any of the switches 31 to 34. Is done.

  The switches 31 to 34 are provided between the single cells 11 to 14 and the constant current circuits 21 and 22, and constitute a switching circuit for flowing the current of the constant current circuits 21 and 22 to one or more single cells that need to be discharged. To do. In this embodiment, a switch having a two-circuit one-contact configuration is used for each of the switches 31-34. The switch 31 has contacts 31-1, 31-2, the switch 32 has contacts 32-1, 32-2, the switch 33 has contacts 33-1, 33-2, and the switch 34 has contacts 34-1, 34-2. The two contacts of each of the switches 31 to 34 are simultaneously turned on (closed) or turned off (opened).

  In this example, the switches 31 to 34 have two circuits and one contact, but each switch 31 to 34 may be configured by using two switches of one circuit and one contact. In addition, although an example using contact switches 31 to 34 is shown here, any circuit switching member for flowing the current of the constant current circuits 21 and 22 to one or a plurality of single cells that need to be discharged can be used. A non-contact circuit switching member such as a MOS-FET or other members can be used.

  The selection circuit 40 is a drive circuit for turning on the switches (31 to 34) corresponding to the single cells that need to be discharged among the single cells 11 to 14, and the control circuit (CPU) of the cell controller described later in detail. The corresponding switches (31 to 34) are turned on in accordance with the cell selection signal from, and the two contacts constituting the switch are simultaneously closed.

  In one embodiment, as will be described in detail later, the switches 31 to 34 and the selection circuit 40 are housed in one IC package as indicated by broken lines in FIG. The switches 31 to 34 in the IC package are connected to the external cells 11 to 14 and the constant current circuits 21 and 22 via terminals CCH, C1 to C5 and CCL of the IC package.

  Next, the operation of the bypass discharge circuit unit of the embodiment shown in FIG. 1 will be described. In the bypass discharge circuit unit of the embodiment, among the four unit cells 11 to 14 constituting the assembled battery 10, the switches 31 to 34 are selectively driven according to the number and position of the unit cells that need to be discharged. That is, the circuit is switched and the current values of the two constant current circuits 21 and 22 are switched.

  FIG. 2 shows a method of switching the current values of the switches 31 to 34 and the constant current circuits 21 and 22 when any one of the four unit cells 11 to 14 constituting the assembled battery 10 is subjected to bypass discharge. FIG. First, when the charging capacity of the unit cell 11 is larger than that of the other unit cells 12 to 14 and only the unit cell 11 is bypass-discharged, the currents of the constant current circuits 21 and 22 as shown in FIG. The value is set to a predetermined value i, the switch 31 is selected and turned on for a predetermined time t.

  Thereby, for the predetermined time t, the current i flows through the path of the unit cell 11 → the constant current circuit 21 → the switch contact 31-2 → the unit cell 11 and at the same time, the unit cell 11 → the switch contact 31-1 → the constant current circuit. The current i flows through a path of 22 → unit cell 14 → unit cell 13 → unit cell 12 → unit cell 11. As a result, as shown in FIG. 2 (a), the current i flows to the cells 12 to 14 that do not require discharge during a predetermined time t, and the cell 11 that requires discharge during the predetermined time t. Since the double current 2i flows, the discharge ratio of the single cells 11, 12, 13, and 14 is 2: 1: 1: 1, and the charge capacity of the single cell 11 is reduced due to the difference in discharge current, so that the other single cells 12 Can be made equal to ~ 14.

  Similarly, when the charging capacity of the unit cell 12 is larger than that of the other unit cells 11, 13, and 14, and only the unit cell 12 is subjected to bypass discharge, as shown in FIG. The current value of 22 is set to a predetermined value i, the switch 32 is selected and turned on for a predetermined time t. Thereby, for the predetermined time t, the current i flows through the path of the unit cell 11 → the constant current circuit 21 → the switch contact 32-2 → the unit cell 12 → the unit cell 11, and at the same time, the unit cell 12 → the switch contact 32-1. The current i flows through the path of the constant current circuit 22 → the cell 14 → the cell 13 → the cell 12.

  As a result, as shown in FIG. 2 (b), the current i flows in the unit cells 11, 13, and 14 that do not require discharge during a predetermined time t, and the unit cell 12 that requires discharge has a predetermined time t. Since twice the current 2i flows between them, the discharge ratio of the single cells 11, 12, 13, and 14 is 1: 2: 1: 1. It can be made equal to the batteries 11, 13, and 14.

  When the charging capacity of the unit cell 13 is larger than that of the other unit cells 11, 12, and 14, and only the unit cell 13 is bypass-discharged, as shown in FIG. Is set to a predetermined value i, the switch 33 is selected and turned on for a predetermined time t. Furthermore, when the charging capacity of the unit cell 14 is larger than that of the other unit cells 11 to 13 and only the unit cell 14 is bypass-discharged, the currents of the constant current circuits 21 and 22 are shown in FIG. The value is set to a predetermined value i, the switch 34 is selected and turned on for a predetermined time t.

  The flow of current during bypass discharge of the unit cell 13 or unit cell 14 is the same as that of the unit cells 11 and 12 described above and will not be described. The charging capacity of the unit cell 14 can be reduced and made equal to other unit cells.

  In FIG. 2, the current value (bypass discharge current value) i of the constant current circuits 21 and 22 and the time for turning on the switches 31 to 34 (bypass discharge time) t are the bypass discharge capacity and the allowable current of the bypass discharge circuit. It is determined as appropriate depending on the relationship between the heat dissipation capacity and the charge / discharge current of the assembled battery 10.

  Next, a method of switching the current values of the switches 31 to 34 and the constant current circuits 21 and 22 when bypass discharge of two of the four unit cells 11 to 14 constituting the assembled battery 10 is performed. explain. FIG. 3 is a diagram showing a method of switching the current values of the switches 31 to 34 and the constant current circuits 21 and 22 when the cells 11 and 13 are subjected to bypass discharge. When the charging capacity of the single cells 11 and 13 is greater than that of the other single cells 12 and 14 and the single cells 11 and 13 are bypass-discharged, the switches 31 to 34 are sequentially switched over the first to third three stages. At the same time, the current values of the constant current circuits 21 and 22 are switched.

  First, in the first stage shown in FIG. 3A, the current value of the constant current circuit 21 is set to a predetermined value i, the current value of the constant current circuit 22 is set to 0, the switch 31 is selected, and a predetermined time t Turn on for As a result, the current i flows through the path of the constant current circuit 21 → the switch contact 31-2 → the cell 11 → the constant current circuit 21 for a predetermined time t. Next, in the second stage shown in FIG. 3B, the current value of the constant current circuit 21 is set to a predetermined value i, the current value of the constant current circuit 22 is set to 0, and the switch 33 is selected for a predetermined time. Turn on for t. Thereby, during a predetermined time t, the current i flows through the path of the constant current circuit 21 → the switch contact 33-2 → the cell 13 → the cell 12 → the cell 11 → the constant current circuit 21.

  Further, in the third stage shown in FIG. 3C, the current value of the constant current circuit 21 is set to 0, the current value of the constant current circuit 22 is set to a predetermined value i, the switch 33 is selected, and a predetermined time t Turn on for As a result, during a predetermined time t, the current i flows through the path of the constant current circuit 22 → the cell 14 → the cell 13 → the switch contact 33-1 → the constant current circuit 22.

  As a result of performing the step-by-step bypass discharge operation from the first stage to the third stage, as shown in FIG. 3, the current i flows through the single cells 12 and 14 that do not need to be discharged during a predetermined time t. Since the current i flows through the unit cells 11 and 13 that require two times during the time 2t, the discharge ratio of the unit cells 11, 12, 13, and 14 is 2: 1: 2: 1, and the difference in discharge time Thus, the charging capacity of the single cells 11 and 13 can be reduced and made equal to the other single cells 12 and 14.

  The case where the unit cells 11 and 13 of the four unit cells 11 to 14 constituting the assembled battery 10 are subjected to bypass discharge has been described as an example, but two unit cells other than the unit cells 11 and 13 are bypassed. Even when discharging, the switches 31 to 34 are sequentially switched over three steps in accordance with the position in the assembled battery 10 of the two unit cells that need to be discharged, and the current values of the constant current circuits 21 and 22 are changed. Switch. The illustration and description of the bypass discharge operation of two unit cells other than the unit cells 11 and 13 are omitted.

  In FIG. 3, the current value (bypass discharge current value) i of the constant current circuits 21 and 22 and the time for turning on the switches 31 to 34 (bypass discharge time) t are the bypass discharge capacity and the allowable current of the bypass discharge circuit. It is determined as appropriate depending on the relationship between the heat dissipation capacity and the charge / discharge current of the assembled battery 10.

  Next, a method of switching the current values of the switches 31 to 34 and the constant current circuits 21 and 22 when three of the four unit cells 11 to 14 constituting the assembled battery 10 are subjected to bypass discharge will be described. explain. FIG. 4 is a diagram illustrating a method of switching the current values of the switches 31 to 34 and the constant current circuits 21 and 22 when the three single cells 11, 13 and 14 are subjected to bypass discharge. When the charging capacity of the single cells 11, 13, and 14 is larger than that of the other single cells 12 and the single cells 11, 13, and 14 are bypass-discharged, the switches 31 to 34 are sequentially switched over the first and second stages. And the current values of the constant current circuits 21 and 22 are switched.

  First, in the first stage shown in FIG. 4A, the current value of the constant current circuit 21 is set to a predetermined value i, the current value of the constant current circuit 22 is set to 0, the switch 31 is selected, and a predetermined time t Turn on for As a result, the current i flows through the path of the constant current circuit 21 → the switch contact 31-2 → the cell 11 → the constant current circuit 21 for a predetermined time t. Next, in the second stage shown in FIG. 4B, the current value of the constant current circuit 21 is set to 0, the current value of the constant current circuit 22 is set to a predetermined value i, and the switch 33 is selected for a predetermined time. Turn on for t. As a result, during a predetermined time t, the current i flows through the path of the constant current circuit 22 → the cell 14 → the cell 13 → the switch contact 33-1 → the constant current circuit 22.

  As a result of performing the step-by-step bypass discharge operation from the first stage to the second stage, as shown in FIG. 4, the unit cells 11 and 13 that do not need to be discharged are not subjected to bypass discharge, and need to be discharged. , 14, the current i flows during a predetermined time t, so that the discharge ratio of the single cells 11, 12, 13, 14 is 1: 0: 1: 1, and the single cells 11, 13, 14 are caused by the difference in discharge current. Can be made equal to other unit cells 12 by reducing the charging capacity.

  Although the case where three unit cells 11, 13, and 14 among the four unit cells 11 to 14 constituting the assembled battery 10 are subjected to bypass discharge has been described as an example, other than the unit cells 11, 13, and 14 has been described. Even when three cells are discharged by bypass, the switches 31 to 34 are sequentially switched over the first stage and the second stage in accordance with the procedure according to the position of the unit cell in the assembled battery 10 that needs to be discharged. The current values of the current circuits 21 and 22 are switched. The illustration and description of the bypass discharge operation of three cells other than the cells 11, 13, and 14 are omitted.

  In FIG. 4, the current value (bypass discharge current value) i of the constant current circuits 21 and 22 and the time for turning on the switches 31 to 34 (bypass discharge time) t are the bypass discharge capacity and the allowable current of the bypass discharge circuit. It is determined as appropriate depending on the relationship between the heat dissipation capacity and the charge / discharge current of the assembled battery 10.

  Next, an embodiment in which the battery control system according to the present invention is applied to an electric vehicle or a hybrid electric vehicle will be described. FIG. 5 is a block diagram showing an overall configuration of a battery control system according to an embodiment mounted on an electric vehicle. In FIG. 5, devices and circuits similar to the devices and circuits of the bypass discharge circuit shown in FIG. In FIG. 5, illustration and description of in-vehicle devices and in-vehicle devices that are not directly related to the battery control system according to the present invention are omitted.

  The vehicle controller 400, the motor controller 300, the battery controller 200, and the cell controller 100 exchange information with each other via a communication circuit installed in the vehicle.

  The vehicle controller 400 controls the traveling speed and braking / driving force of the vehicle based on an operation signal from a vehicle driving operation device such as an accelerator pedal, a brake pedal, or a shift lever operated by a driver of the electric vehicle. The motor controller 300 controls the battery controller 200 and the inverter 340 based on the speed command and braking / driving force command from the vehicle controller 400, and controls the rotational speed and torque of the vehicle travel drive motor 350.

  The battery controller 200 is configured to charge and discharge the battery 10 based on the voltage, current, and temperature of the battery (assembled battery) 10 detected by the voltage sensor 210, the current sensor 220, and the temperature sensor 230. In addition to controlling the charge state, the cell controller 100 is controlled to manage the charge capacities of the plurality of single cells (cells) 11 to 14 constituting the battery 10, and the charge capacity variation correction (cell balance) is performed. Do.

  The vehicle controller 400, the motor controller 300, the battery controller 200, and the motor 350 are not directly related to the charge capacity variation correction control of the cells 11 to 14 according to the present invention, that is, the bypass discharge control described above. The detailed description of is omitted.

  The cell controller 100 includes a voltage detection circuit 50, a multiplexer 60, a control circuit (CPU) 70, and the like in addition to the switch circuit 30 and the selection circuit 40 shown in FIG. Is detected, the charging capacity of each unit cell is checked, the switch circuit 30 is driven by the selection circuit 40, the unit cells 11 to 14 having a high charging capacity are connected to the constant current circuit 20, and the constant current circuit 20 is charged. A constant current is passed through the high capacity cells 11 to 14 to discharge them.

  Since the cell controller 100 of one embodiment does not have a high-temperature heating element such as a discharge resistor of a conventional bypass discharge circuit, the cell controller 100 is housed in one IC package.

  The DC power charged in the battery 10 is supplied to the smoothing capacitor 330 and the inverter 340 via the switches 310 and 320, converted into AC power by the inverter 340 and applied to the AC motor 350, and the AC motor 350 is driven. Is called. On the other hand, when the vehicle is braked, AC power generated by the AC motor 350 is converted into DC power by the inverter 340, smoothed by the smoothing capacitor 330, and applied to the battery 10 via the switches 310 and 320. Is charged.

  In the battery control system according to the embodiment shown in FIG. 5, a battery (assembled battery) 10 in which four unit cells (cells) 11 to 14 are connected in series will be described as an example. As for the battery mounted in the battery, more single cells are connected in series and parallel, and a high-voltage, high-capacity battery with a voltage at both ends of several hundred volts is common. Of course, for such a high-voltage, high-capacity battery Also, the present invention can be applied.

  FIG. 6 is a circuit diagram showing an embodiment of the switch circuit 30. In FIG. 6, devices and circuits similar to those shown in FIG. In this switch circuit 30, instead of the switch contacts 31-1, 31-2, 32-1, 32-2, 33-1, 33-2, 34-1 and 34-2 shown in FIG. , 312, 321, 322, 331, 332, 341, 342, and backflow prevention diodes D <b> 1 to D <b> 8 are connected in series with these MOS-FETs. The MOS-FETs 312, 322, 332, and 342 are connected to the selection circuit 40 via level shifters (inverters) INV1 to INV4.

  In the switch circuit 30 shown in FIG. 6 as well, as in the switches 31 to 34 shown in FIG. 1, the selection circuit 40 turns on or off the MOS-FETs 311, 312, 321, 322, 331, 332, 341, and 342, and sets the constant. The current circuits 21 and 22 cause a constant current to flow to one or a plurality of single cells 11 to 14 that need to be discharged.

  FIG. 7 is a circuit diagram showing an embodiment of the constant current circuit 21. In addition, the same code | symbol is attached | subjected and demonstrated to the apparatus and circuit similar to the apparatus and circuit shown in FIG. When a voltage signal corresponding to the current setting value of the constant current circuit 21 is applied to the bias terminal (+ terminal) of the operational amplifier A11, it is amplified by the operational amplifier A11 and input to the transistor Tr11 via the bias resistor R11. Thereby, a current flows from the + terminal of the assembled battery (battery) 10 to the − terminal of the assembled battery 10 via the transistor Tr12, the transistor Tr11, and the bypass current detection resistor R12. At this time, a voltage corresponding to the bypass current is generated at both ends of the resistor R12, and this voltage is fed back to the negative terminal of the operational amplifier A11. The operational amplifier A11 causes the transistor Tr11 to have a constant value according to the current set value of the constant current circuit 21. Collector current flows.

  The transistors Tr12 and Tr13 are current mirror circuits. When a constant current corresponding to the current setting value of the constant current circuit 21 flows through the transistor Tr12, the switch circuit 30 of the switch circuit 30 is connected from the + terminal of the assembled battery 10 via the transistor Tr13. A constant current corresponding to the current setting value of the constant current circuit 21 flows to the terminal CCH. That is, in the constant current circuit 21, when a voltage signal corresponding to the current setting value of the constant current circuit 21 is applied to the bias terminal (the + terminal of the operational amplifier A11), the terminal of the switch circuit 30 is changed from the + terminal of the assembled battery 10. A constant current equal to the current set value of the constant current circuit 21 is supplied to CCH.

  FIG. 8 is a circuit diagram showing an embodiment of the constant current circuit 22. In addition, the same code | symbol is attached | subjected and demonstrated to the apparatus and circuit similar to the apparatus and circuit shown in FIG. When a voltage signal corresponding to the current setting value of the constant current circuit 22 is applied to the bias terminal (the + terminal of the operational amplifier A21), the voltage signal is amplified by the operational amplifier A21 and input to the transistor Tr21 via the bias resistor R21. As a result, a current flows from the terminal CCL of the switch circuit 30 to the negative terminal of the assembled battery 10 via the transistor Tr21 and the bypass current detection resistor R22. At this time, a voltage corresponding to the bypass current is generated at both ends of the resistor R22, and this voltage is fed back to the negative terminal of the operational amplifier A21. The operational amplifier A21 causes the transistor Tr21 to have a constant value according to the current set value of the constant current circuit 22. Collector current flows.

  That is, in the constant current circuit 22, when a voltage signal corresponding to the current setting value of the constant current circuit 22 is applied to the bias terminal (+ terminal) of the operational amplifier A 21, the terminal CCL of the switch circuit 30 − A constant current equal to the current set value of the constant current circuit 22 is supplied to the terminal.

  The configurations of the constant current circuits 21 and 22 are not limited to the embodiments shown in FIGS.

  Here, the heat generation in the bypass discharge circuit unit of the embodiment is compared with the heat generation in the conventional bypass discharge circuit unit. As described above, in the conventional bypass discharge circuit section, a series connection of a bypass resistor and a switching element is connected in parallel to each unit cell, and the switching elements of all the unit cells that perform the bypass discharge are turned on. Since a discharge current is caused to flow through, bypass resistors connected in parallel to all the cells that perform bypass discharge generate heat. For this reason, it is difficult to take measures against heat dissipation, and the bypass discharge circuit section becomes large, which makes it difficult to incorporate it into the battery device.

  In the bypass discharge circuit portion of this embodiment, since no bypass resistor is used, heat is not generated by the bypass resistor, but heat is generated due to loss of the constant current circuits 21 and 22. In the constant current circuit 21 shown in FIG. 7, the transistors Tr12 and Tr13 constituting the current mirror circuit generate relatively little heat, but the transistor Tr11 generates heat. Further, in the constant current circuit 22 shown in FIG. 8, the transistor Tr21 generates heat. The heat generation capacities of these transistors Tr11 and Tr21 correspond to the discharge capacities of one or more single cells to be discharged, and are the same as the heat dissipating capacities of conventional bypass discharge resistors.

  However, the transistors Tr11 and Tr21 that generate a large amount of heat can be radiated relatively easily by using a heat radiating member such as a heat sink as compared with the heat generated by a conventional unspecified number of bypass discharge resistors. Further, as described with reference to FIG. 5, by disposing the constant current circuit 20 (21, 22) separately from the cell controller 100, it becomes possible to exclude the heat radiator from the cell controller 100, It can be housed in a single IC package, the device can be miniaturized, and the battery control system can be easily manufactured and incorporated in the on-vehicle battery device.

  FIG. 9 is a circuit diagram showing an embodiment of the voltage detection circuit 50, the multiplexer 60 and the control circuit 70. Both ends of each of the unit cells 11 to 14 of the assembled battery (battery) 10 are connected to the + terminal and the − terminal of the differential amplifiers A51 to A54, and each of the differential amplifiers A51 to A54 has a voltage across the unit cells 11 to 14 ( A voltage signal corresponding to the cell voltage is output.

  The multiplexer 60 sequentially switches the output voltage signals of the differential amplifiers A51 to A54 according to the multiplexer input switching signal output from the port of the control circuit (CPU) 70, and connects to the AD input terminal of the control circuit 70. The control circuit 70 AD-converts the output voltage signals of the differential amplifiers A51 to A54 input from the multiplexer 60 to the AD input terminal, and detects the voltages (cell voltages) across the unit cells 11 to 14.

  FIG. 10 is a flowchart illustrating cell balance (charge capacity variation correction) control according to an embodiment. A control circuit (CPU) 70 of the cell controller 100 starts cell balance control in accordance with a cell balance start command from the battery controller 200. Here, the cell balance control of the battery (assembled battery) 10, the constant current circuits 21 and 22, the cell controller 100, and the battery controller 200 according to the embodiment shown in FIGS. 5 to 9 will be described as an example.

  In step 1, the OCV (Open Circuit Voltage) of each of the cells 11 to 14 is measured. Specifically, the memory of the control circuit 70 is based on the voltages of the individual cells 11 to 14 detected by the voltage detection circuit 50, the multiplexer 60 and the control circuit 70 shown in FIG. 9 and the current detected by the current sensor 220. From a function of the charge / discharge current and voltage of the cells 11 to 14 stored in advance (not shown), the voltage when the current is 0 A is calculated as OCV.

  In step 2, it is checked whether the OCVs of the individual cells 11 to 14 are distributed within a preset specified range. FIG. 11 shows an example of the distribution frequency of the open circuit voltage OCV of a plurality of single cells. When the OCVs of all the cells 11 to 14 are distributed within the specified range, this cell balance control is terminated. If there is a single cell whose OCV is higher than the specified range, the process proceeds to step 3 to calculate the SOC of the single cell whose OCV shows an average value and the single cell whose OCV is higher than the specified range. Note that the SOC detection method is not limited to the calculation method of this embodiment.

In the subsequent step 4, the discharge time, that is, the switching circuit 30 is turned on based on the difference between the SOC of the single cell whose OCV is an average value and the SOC of the single cell whose OCV is higher than the specified range, the nominal capacity of the single cell, and the ambient temperature. The time and the bypass discharge current, that is, the current set values of the constant current circuits 21 and 22 are determined. For example, when the SOC difference is A% and the nominal capacity of the cells 11 to 14 is K (Ah), the discharge capacity Z (Ah) of the cell whose OCV is higher than the specified range is
Z = K · (A / 100) (Ah) (1)
It becomes.

  Here, the bypass discharge current (the current setting value of the constant current circuits 21 and 22) is determined according to the ambient temperature of the battery 10. For example, the bypass discharge current when the ambient temperature of the battery 10 is a predetermined value is iA, and when the ambient temperature is higher than the predetermined value, the bypass discharge current is decreased as the ambient temperature increases. On the other hand, when the ambient temperature is lower than the predetermined value, the bypass discharge current is increased as the ambient temperature is lowered. After the bypass discharge current is determined according to the ambient temperature, the discharge time is determined from the discharge capacity Z (Ah) obtained by equation (1).

  When the ambient temperature of the battery 10 is high, the current setting value of the constant current circuits 21 and 22 is lowered, so that the discharge time becomes long, but the transistors Tr11 and Tr21 of the constant current circuits 21 and 22 (see FIGS. 7 and 8). ) Is prevented from generating heat per unit time. On the contrary, when the ambient temperature of the battery 10 is low, the current setting value of the constant current circuits 21 and 22 is increased, so that the discharge time is shortened and the cell balance can be achieved in a short time.

  In step 5, the MOS-FET (see FIG. 6) of the switch circuit 30 corresponding to the single cell whose OCV is higher than the specified range and must be subjected to bypass discharge is turned on to start constant current discharge. In step 6, it is confirmed whether or not the bypass discharge time determined in step 4 has elapsed. If the discharge time has elapsed, the process proceeds to step 7 and the MOS-FET of the switch circuit 30 corresponding to the discharge target cell is turned off. Then, the constant current discharge is finished.

  Depending on the number and position of the cells to be discharged, switching of the switch circuit 30, switching of the current setting values of the constant current circuits 21, 22 or switching of the switch circuit 30 in stages is performed as appropriate. The current setting values of the current circuits 21 and 22 are switched.

  In the above-described embodiment, the battery (assembled battery) 10 in which four unit cells 11 to 14 are connected in series has been described as an example. Generally, an electric vehicle has a high terminal voltage and a large charging capacity. Since a battery is required, a battery in which more single cells are connected in series and parallel is used. The battery control system of the present invention can also be applied to such a high-voltage, large-capacity battery.

  FIG. 12 shows a configuration of a modification in which the cell controller 100 of one embodiment is applied to a battery (assembled battery) 10A in which eight unit cells 11 to 18 are connected in series. In FIG. 12, the cell controller 101 is used for the cells 11 to 14, and the cell controller 102 is used for the cells 15 to 18, respectively. These cell controllers 101 and 102 are the same as the cell controller 100 shown in FIGS. 5 to 9, and are housed in IC packages.

  The terminal CCH-1 of the cell controller 101 is connected to the + terminal of the unit cell 11 through the constant current circuit 21, and the terminal CCL-2 of the cell controller 102 is connected to the-terminal of the unit cell 18 through the constant current circuit 23. Has been. The terminal CCL-1 of the cell controller 101 is connected to the terminal CCH-2 of the cell controller 102 via the constant current circuit 22.

  The switches 31 to 34 of the cell controller 101 are driven by the selection circuit 41, and the switches 35 to 38 of the cell controller 102 are driven by the selection circuit 42. These selection circuits 41 and 42 are the same as the selection circuit 40 shown in FIGS. Instead of the switches 31 to 34, a switching circuit using a MOS-FET as shown in FIG. 6 may be used. Note that the voltage detection circuit 50, the multiplexer 60, and the control circuit 70 of the cell controller 101 and the cell controller 102 are not shown.

  FIG. 13 shows a configuration of another modification in which the cell controller 100 of one embodiment is applied to a battery (assembled battery) 10A in which eight unit cells 11 to 18 are connected in series. In FIG. 13, the cell controller 103 is used for the cells 11 to 14, and the cell controller 104 is used for the cells 15 to 18. Each of these cell controllers 103 and 104 is provided with two terminals CCL and CCH, but other than that, it is the same as the cell controller 100 shown in FIGS. 5 to 9, and each is housed in an IC package. ing.

  The terminal CCH-1 of the cell controller 103 is connected to the + terminal of the cell 11 via the constant current circuit 21, and the terminal CCL-1 of the cell controller 103 is connected to the terminal CCL-2 of the cell controller 104, and the terminal of the cell controller 103. CCH-1 is connected to terminal CCH-2 of cell controller 104, respectively. The terminal CCL-2 of the cell controller 104 is connected to the negative terminal of the unit cell 18 through the constant current circuit 22. In the example shown in FIG. 13, the constant current circuit (corresponding to the constant current circuit 22 shown in FIG. 12) between the cell controllers 103 and 104 can be omitted.

  The battery control system of the present invention is also applied to a battery in which more single cells are connected in series and parallel by cascading cell controllers as shown in FIG. 12 or 13 according to the number of single cells. be able to.

  In the above-described embodiment and its modification, an example is shown in which cell balance control is performed on four unit cells in which one cell controller is connected in series. The same applies to the case of performing cell balance control of three or five or more single cells. As the number of cells connected in series increases, the number of stages for switching the switch circuit and the current setting value of the constant current circuit increases, so the relationship between the time required for cell balance control of the entire battery and heat dissipation. Therefore, it is desirable to determine the optimum number of single cells per cell controller.

  In the above-described embodiment and its modifications, any type of secondary battery such as a lithium ion battery or a nickel metal hydride battery can be applied to the secondary battery (unit cell or cell) constituting the battery (assembled battery). it can.

  In particular, in a lithium ion battery having a high energy density and requiring attention to overcharging, it is indispensable to detect the voltage of the unit cell in order to ensure safety. In addition, since the lithium ion battery cannot correct the variation in charge capacity due to overcharging unlike the nickel metal hydride battery, if the charge capacity between the secondary batteries varies, the chargeable / dischargeable capacity of the battery is reduced. In addition, since the deterioration state of the secondary battery is different, the life as the battery is shortened, and it is important to correct the variation in the charge capacity between the secondary batteries.

  Therefore, by applying the battery control system according to the present invention to a battery device in which a plurality of lithium ion batteries are connected in series, the heat dissipation process of the bypass discharge circuit section is facilitated, and the incorporation into the battery device is facilitated. A remarkable effect is obtained.

  In the above-described embodiment and its modification, an example in which the battery control system according to the present invention is applied to a battery device of an electric vehicle or a hybrid electric vehicle is shown. However, the battery control system of the present invention is not limited to an electric vehicle. It can be applied to a battery device for any application.

  In the above-described embodiments and their modifications, all combinations of the embodiments or the embodiments and the modifications are possible.

  According to the above-described embodiment and its modifications, the following operational effects can be obtained. First, in a battery control system that corrects variation in the state of charge SOC between secondary batteries in the assembled battery 10 in which a plurality of secondary batteries 11 to 14 are connected in series, the voltage detection circuit 50, the multiplexer 60, and the control circuit 70 While detecting the charge state of each secondary battery 11-14, the control circuit 70 determines the necessity of discharge of each secondary battery 11-14 based on the charge state of each secondary battery 11-14, and a switch circuit 30, the selection circuit 40 and the control circuit 70 switch the circuit so that the constant current of the constant current circuits 21 and 22 flows to the secondary battery that needs to be discharged. The heat generated by the transistors of the current circuits 21 and 22 is replaced, and the transistors of the constant current circuits 21 and 22 are generated. It can easily be dissipated processed by using a heat radiation member such as heat sink.

  Furthermore, by making the constant current circuits 21 and 22 serving as heat sources separate from the cell controller 100 including the switch circuit 30, the selection circuit 40, the voltage detection circuit 50, the multiplexer 60 and the control circuit 70, Since it becomes possible to exclude the heat radiator from the cell controller 100, the cell controller 100 can be housed in one IC package, the device can be miniaturized, and the battery control system can be manufactured and the battery can be reduced. Easy integration into the device.

  Further, according to the embodiment and the modification thereof, the switch circuit 30, the selection circuit 40, and the control circuit 70 require discharge according to the position of the secondary battery determined to be discharged in the assembled battery 10. Since the circuit is switched so that the constant current of the constant current circuits 21 and 22 flows through the secondary battery, the secondary battery is constant regardless of the position in the assembled battery 10 where the secondary battery requiring discharge is located. It can be discharged by passing an electric current.

  According to the embodiment and the modification thereof, the secondary battery that needs to be discharged by the switch circuit 30, the selection circuit 40, and the control circuit 70 according to the number of secondary batteries that are determined to be discharged by the control circuit 70. The constant current circuits 21 and 22 are switched so that a constant current flows therethrough. Therefore, regardless of the number of secondary batteries that need to be discharged in the assembled battery 10, a constant current is supplied to the secondary batteries. It can be discharged.

  According to the embodiment and the modification thereof, the switching of the circuit by the switch circuit 30 and the constant current circuits 21 and 22 are performed in a predetermined procedure according to the position and the number of secondary batteries in the assembled battery determined to be discharged. Therefore, regardless of the number and position of the secondary batteries that need to be discharged in the assembled battery 10, it is possible to discharge the secondary batteries by passing a constant current. it can.

  According to the embodiment and its modification, the control circuit 70 changes the current value of the constant current circuits 21 and 22, that is, the bypass discharge current value according to the ambient temperature of the assembled battery 10 detected by the temperature sensor 230. Thus, the amount of heat generated by the constant current circuits 21 and 22 can be adjusted according to the ambient temperature, and the temperature of the constant current circuits 21 and 22 can be kept appropriate.

  According to the embodiment and the modification thereof, the switch circuit 30, the selection circuit 40, the voltage detection circuit 50, the multiplexer 60, and the control circuit 70 are accommodated in the IC package. This makes it easy to manufacture a battery control system and incorporate it into an in-vehicle battery device.

  According to one embodiment and its modification, a plurality of secondary batteries constituting an assembled battery are grouped into a predetermined number, and a switch circuit 30 and a selection circuit corresponding to the predetermined number of secondary batteries belonging to each group 40, the voltage detection circuit 50, the multiplexer 60, and the control circuit 70 are housed in separate IC packages, so that the device can be downsized even for an assembled battery in which a large number of secondary batteries are connected in series. This facilitates the manufacture of the battery control system and the incorporation into the in-vehicle battery device.

10; assembled battery (battery), 11 to 18; secondary battery (unit cell, cell), 20, 21, 22, 23; constant current circuit, 30; switch circuit, 31 to 34; switch, 40; 50; voltage detection circuit, 60; multiplexer, 70; control circuit, 100; cell controller, 230; temperature sensor, 311, 312, 321, 322, 331, 332, 341, 342;

Claims (4)

In a battery control system for correcting variations in the charging state between the secondary batteries in an assembled battery in which a plurality of secondary batteries are connected in series,
A charge state detection circuit for detecting a charge state of each of the secondary batteries;
A determination circuit for determining whether or not each of the secondary batteries needs to be discharged based on a charge state of the secondary battery detected by the charge state detection circuit;
A constant current circuit for supplying a constant current to the secondary battery;
A switching circuit that switches a circuit to flow the constant current of the constant current circuit to one or more of the secondary batteries;
A control circuit for switching the circuit by the switching circuit so that the constant current of the constant current circuit flows to the secondary battery determined to be discharged by the determination circuit ;
The control circuit performs switching of the circuit by the switching circuit and the current value of the constant current circuit in a predetermined procedure according to the position and number of the secondary batteries in the assembled battery determined to be discharged by the determination circuit. The battery control system is characterized in that switching between the two is performed in stages . The battery control system according to claim 1 , wherein
A temperature detection circuit for detecting an ambient temperature of the assembled battery;
The battery control system, wherein the control circuit changes a current value of the constant current circuit according to an ambient temperature of the assembled battery detected by the temperature detection circuit. The battery control system according to claim 1 or 2 ,
A battery control system, wherein the charge state detection circuit, the determination circuit, the switching circuit, and the control circuit are housed in an IC package. In the battery control system according to any one of claims 1 to 3 ,
The plurality of secondary batteries constituting the assembled battery are grouped into a predetermined number, and the charging state detection circuit corresponding to the predetermined number of the secondary batteries belonging to each group, the determination circuit, the switching circuit, and A battery control system, wherein the control circuits are housed in separate IC packages.

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