JP2001218376A - Device and method for controlling charring condition of single batteries constituting batter pack, and battery module using device, and electric-motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in a conventional battery pack, where a plurality of nickel hydrogen batteries or the like are connected in series, such as in the voltage of each battery cell gradually becomes unequal and that the management takes much time. SOLUTION: A voltage Vi across the terminals of each single battery ECi is detected, and when the maximum value of the dispersion gets over a prescribed value, its discharge switch Ti is closed as to a single battery ECi, where the dispersion is on a certain level or higher, thereby forming a closed circuit passing a discharge resistor Ri. As a result, only the battery ECi where the voltage is high is discharged, and the dispersion of voltage across terminals is equalized. Since there is no need to perform charge separately for each single battery ECi, the circuit is simplified, and leveling can be performed easily. As a result, the rise of reliability and the service life prolongation of a battery pack, where single batteries are combined and a vehicle where this battery pack is mounted, can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery control device for controlling the amount of electric power of an assembled battery composed of a plurality of unit cells connected in series, and more particularly to an electrically driven moving body (for example,
The present invention relates to a battery pack control device optimized for managing a battery pack mounted as a power source of a vehicle, a motorcycle, a forklift, a cart, a vehicle, etc., which is electrically driven at least temporarily.

[0002]

2. Description of the Related Art Conventionally, as a power source for an electrically driven moving body, it is general to use an assembled battery in which a plurality of cells are connected in series in order to meet demands for high voltage and large capacity. In this type of assembled battery, despite the fact that the entire assembled battery is charged / discharged, the remaining capacity of each unit cell has a different value based on the manufacturing atmosphere and the operating atmosphere such as temperature and humidity. turn into. If the battery pack, which is an aggregate of cells with different remaining capacities, is used repeatedly as it is, the cells with higher remaining capacity will be overcharged, while the cells with lower remaining capacity will be overdischarged. Sometimes. In particular, when a high-performance lithium-ion battery is used as a unit cell, the range of the rated use potential may be narrow, and if the potential is abnormally lowered due to overdischarge, the deterioration will accelerate. In the case where an assembled battery is used as a power source for an electrically driven moving body, charging and discharging may be performed up to the capacity limit of the assembled battery in order to extend the moving distance per charge. When this is repeated, the voltage will eventually fluctuate, leading to a problem of shortening the life of the unit cell.

[0003] Conventionally, optimal management of single cells has been performed, and Japanese Patent Application Laid-Open No. 10-32936 has disclosed that the remaining capacity of each single cell is detected, and the difference in the remaining capacity of each single cell is small. A control system for individually charging or discharging each unit cell has been proposed. According to this control system, the remaining capacity of the cells constituting the assembled battery can be equalized at an appropriate time, and the cells can be effectively used for a long period of time.

[0004]

However, the following problems have not been solved in the conventional control system, which has been a serious problem in practical use. The remaining capacity of the cell is calculated by integrating
It can be measured by measuring the internal resistance or the like, but for this measurement, it is necessary to measure the voltage-current of each cell, store the result, calculate the power value, and the like. Therefore, not only a logical operation circuit centered on a CPU, various sensors, and the like are required as control devices for performing main information processing, but also
It is necessary to connect the control device and each unit cell with a plurality of signal lines, and the whole apparatus becomes large, heavy, and complicated. For this reason, it has been considered that it may be difficult to mount on an electrically driven moving body.

[0005] Further, if it is attempted to control the charging of each unit cell individually, a mechanism for charging each unit cell connected in series is required, and the device becomes complicated and large. On the other hand, it is conceivable to incorporate a control device for the amount of charge into the unit cell itself.In this case, however, not only is the expendable battery expensive, but also the control circuit is replaced when the battery is replaced. Therefore, from the viewpoint of resource saving, it becomes less practical.

As a technique for easily eliminating the difference in the remaining capacity of a plurality of cells in an assembled battery, Japanese Patent Laid-Open No. 5-15 / 1993 has been proposed.
No. 076 discloses that a discharge circuit is provided for each cell,
A technique has been proposed in which all cells are completely discharged before charging the assembled battery. According to this technique, it is not necessary to measure the remaining capacity of the unit cell, and the problem included in the control system is temporarily solved. However, every time the assembled battery is charged, all the electric power remaining in the unit cell is wasted. It will be consumed and cannot be adopted environmentally or economically. For example, in an electric vehicle that runs on battery power or a hybrid vehicle that runs using both an engine and an electric motor, charge / discharge control of the assembled battery is performed with a target remaining battery capacity of about 60%. In such a case, if all the remaining power is discharged to equalize the charged amount, more than half of the power charged in each battery is wasted. In addition, since the capacity of the unit cells is equalized only when charging the assembled battery, the unit cells cannot be equalized at an appropriate time, such as when the electrically driven moving body is moving, and even when charging. Would take a considerable amount of time.

The present invention has been made in order to solve the above-mentioned problems, and has as its object to easily equalize the remaining capacity at an appropriate time while effectively utilizing the remaining capacity of a unit cell.
Another object is to simplify the configuration of the device, to improve reliability, to reduce the size of the device, and to ensure economic efficiency.

[0008]

Means for Solving the Problems and Their Functions and Effects In order to solve the above problems, a battery pack control device of the present invention controls the electric energy of a battery pack composed of a plurality of unit cells connected in series. A battery cell control device, wherein the battery cell controller detects a variation in voltage value of each of the plurality of unit cells, a unit cell discharging unit that discharges any of the unit cells, and the unit cell control unit detects the variation. The gist of the invention is to provide a cell discharge control means for controlling the cell discharge means so that the variation of the voltage value of the cell is within an allowable range.

Further, the invention of a control method corresponding to the unit cell discharge control device is a method for controlling charging / discharging of an assembled battery composed of a plurality of unit cells connected in series. The variation of each voltage value is detected, and when the variation of the detected voltage value of the single cell is out of the allowable range, one or more single cells are identified from those having the highest voltage values, and the identified single cells are identified. The gist is to discharge the cell.

According to these inventions, it is only necessary to control the discharge of the unit cells so that the variation of the voltage value of the unit cells becomes an allowable value. The variation in the state of charge can be controlled within an allowable range. In such a configuration, the voltage value of the unit cell or its variation is simply detected and the state of charge of each unit cell is equalized only by discharging, so that the circuit configuration can be simplified. Equalizing the state of charge of the cells is extremely useful for extending the life of the assembled battery.

[0011] The battery pack control apparatus or control method of the present invention detects variations in the voltage of the cells and equalizes the remaining capacity by discharging, so that the remaining capacity of the cells can be effectively utilized. The remaining capacity can be equalized at an appropriate time. Moreover, the configuration can be simplified, the reliability is excellent, and the size can be reduced. As a result, it is particularly useful as an assembled battery control device for an electrically driven moving body.

[0012] The cell discharge control means may detect the voltage value of the cell and detect a variation in the voltage value with reference to the detected minimum value of the cell.
The voltage value of the unit cell or the variation of the voltage value detected by these configurations is treated as a state of charge of the unit cell or a parameter corresponding to the variation. The charge state can be estimated from the voltage value because, for example, in a secondary battery such as a lithium-based battery, a high correlation exists between the voltage and the charge state. In the present invention, the necessary information is obtained by the voltage value by skillfully utilizing such characteristics of the unit cells, and the remaining capacity of the unit cells is equalized by discharging which requires only a simple circuit configuration.

[0013] In such a battery pack control device, the cell discharge control means can provide a predetermined width to the allowable value of the variation of the cell, activates the cell discharge means at the upper limit of the width, and sets the predetermined width. It is preferable to stop the cell discharging means at the lower limit. With the width of the allowable value, it is possible to provide hysteresis to the operation of the unit cell discharging unit, and prevent the unit cell discharging unit from frequently discharging the unit cell. As a result, the life of the battery pack can be further extended.

Further, the cell discharge control means can estimate the condition of the battery pack based on information over time for controlling the cell discharge means. Here, the time-dependent information for controlling the unit cell discharging unit includes a cumulative value of the number of times of control of the unit cell discharging unit for a specific battery pack, a control frequency, a control interval, a number of control times per unit time, and the like. Such time-dependent information for controlling the unit cell discharging means indicates the frequency of occurrence of variation in the remaining capacity of each unit cell as described above, and should be used as a parameter indicating indirectly the deterioration of the unit cell. May be possible. Therefore, it is possible to accurately estimate the state of the battery pack based on the time-dependent information for controlling the cell discharging means. Accordingly, the operation of the unit cell charging means can be stopped based on this information. Note that the estimation result can be used in the same manner as ordinary vehicle information. For example, a normal, warning, or abnormal level is displayed on the indicator panel, a warning is issued only when an abnormality is detected, or the information is output as maintenance information during a periodic inspection of the vehicle.

The cell discharging means may have any circuit configuration as long as discharging can be performed for each cell. For example, a resistor and a switch are provided for each cell, and a cell-switch-resistance is used. It can be provided to form a closed circuit consisting of a container, and the discharge can be controlled by turning on and off a switch. With a simple configuration, it is possible to control the discharge of the unit cell.

Although various types of cells can be used as the unit cell, it is particularly useful to use a unit cell in which battery charge management is strict. As such a single battery, various types of batteries such as a lithium-based battery, for example, a lithium ion battery, a lithium polymer battery, a lithium-nickel battery, and a lithium-cobalt battery can be considered. Of course, the present invention is not limited to lithium-based batteries, and can be applied to other types of batteries such as nickel-metal hydride.

A battery module according to the present invention is a battery module including an assembled battery composed of a plurality of cells and a control device for controlling a state of charge of the assembled battery. The cells are connected in series, and the control device includes: a variation detection unit configured to detect a variation in a voltage value of each of the plurality of unit cells; a unit cell discharge unit configured to discharge any of the unit cells; The gist of the present invention is to provide a cell discharge control means for controlling the cell discharge means such that the fluctuation of the voltage value of the cell detected by the fluctuation detection means is within an allowable range.

This battery module can detect the variation in the state of charge of each cell and equalize it, so that the reliability as a battery module can be ensured with a simple configuration.

An electric vehicle according to the present invention further includes an assembled battery including a plurality of cells, a control device for controlling a state of charge of the assembled battery, and an electric motor driven by the assembled battery. Wherein the assembled battery includes the plurality of cells connected in series, and the control device includes a variation detection unit configured to detect a variation in a voltage value of each of the plurality of cells; A cell discharge means for discharging the battery, and a cell discharge control means for controlling the cell discharge means, such that the variation in the voltage value of the cell detected by the variation detection means is within an allowable range, The gist is that the electric motor is driven by the electric power of the battery pack and outputs power to a vehicle drive shaft.

In this electric vehicle, the variation in the state of charge of each cell constituting the assembled battery mounted thereon can be detected and equalized, so that the reliability of the assembled battery can be ensured with a simple configuration. be able to. Therefore, it is possible to reduce the weight and secure the reliability of the vehicle when the battery pack is employed as the electric vehicle.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, an embodiment of a battery pack control device of the present invention will be described below. FIG. 1 is a circuit diagram of a power supply unit of an electric vehicle employing an assembled battery control device 10 according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the assembled battery control device 10, and FIG. 1 is a schematic configuration diagram of an electric vehicle employing a device. First, the configuration of the electric vehicle will be described with reference to FIG. 3, and then the details of the battery pack control device 10 will be described with reference to FIGS. 1 and 2.

As shown in FIG. 3, this electric vehicle 1
A generator 100, a gasoline engine 110 that drives the generator 100, and an electric motor 120 as a vehicle power source
And a power control circuit 130 that supplies electric power from the power supply unit 125 to the electric motor 120, and a drive system 150 that finally transmits the power of the electric motor 120 to the wheels 140. That is, the vehicle 1 uses the power of the engine 110 to generate electric power with the generator 100, and the electric power is supplied to the power supply unit 125 as needed.
Is a so-called series hybrid vehicle in which the battery pack built in the vehicle is charged and the electric motor 120 is driven by the electric power of the power supply unit 125 to drive the vehicle.

As shown in FIG. 1, the power supply unit 125 of the electric vehicle 1 includes a battery module SB for connecting a large number of assembled batteries BA in parallel to obtain a necessary large current, and a power supply control for controlling the battery module SB. And a unit ECU. The power supply unit 125 includes a plurality of battery packs BA connected in parallel.
Is provided, and outputs information necessary for managing the total voltage, total current, temperature, etc. of the power supply unit 125 to the power supply control unit ECU.
In the present embodiment, since the battery module SB is managed by the battery pack control device 10 described later, it is not necessary for the power supply control unit ECU to manage the deterioration state of a large number of single batteries EC or the battery packs BA. Instead, only the simplified normal management based on the existence of the stable battery module SB is executed. Therefore, the amount of information transmitted and received between the battery pack management circuit BC and the power supply control unit ECU only needs to be comprehensive information of the battery module SB, and the number of wires and connections between them are simplified. The assembled battery BA uses a lithium ion battery having excellent voltage-capacity characteristics as a unit cell EC. In order to obtain a required high voltage, a plurality of the unit cells (about 80 in this embodiment) are connected in series. It is configured.

The battery pack control device 10 of the present embodiment is an electric circuit integrally formed with each battery pack BA. Although not shown in FIG. 1, the battery pack control apparatus 10 is paired with each of the battery packs BA connected in parallel. It is equipped with. As shown in FIG. 2, the battery pack BA includes i unit cells EC1, EC2,.
It consists of ECi. Hereinafter, members provided in accordance with the number of the i unit cells are typically represented using a subscript “i”.

The battery pack control device 10 provided for each battery pack BA is used to control the number i of cells EC constituting the battery pack BA.
cell voltage detection circuit 1 for detecting each voltage value of i
2, a unit cell discharging circuit 14 for individually discharging the i unit cells ECi, and a unit cell voltage detecting circuit 12
And a unit cell discharge control unit 16 that drives the unit cell discharge circuit 14 by inputting a signal from the unit. Here, the cell voltage detection circuit 12 is configured by i differential amplifiers DAMi connected to both terminals of each cell EC. The cell discharge circuit 14 is composed of i number of discharge resistors Ri and discharge switches Ti. When the discharge switch Ti is turned on, a closed circuit that consumes the power of the cells ECi via the resistors Ri is provided. It is a simple electric circuit to be formed.

The single-cell discharge control unit 16 includes the maximum value detection unit 1
6a, minimum value detecting section 16b, variation determining section 16c, cell voltage variation detecting section 16d, discharge switch operating section 1
6e. The maximum value detection unit 16a is connected to the outputs of the i number of differential amplifiers DAMi of the cell voltage detection circuit 12, and receives the signals of the i number of voltage values V1, V2,... From the differential amplifier DAMi. The circuit detects the maximum value Vmax of the respective voltage values V1, V2, V3,..., Vi. Similarly, the minimum value detection unit 16b
The voltage values V1, V from the respective differential amplifiers DAMi
2, V3,..., Vi are circuits for detecting the minimum value Vmin. These maximum value detection unit 16a and minimum value detection unit 16
The detection result with b is output to the variation determination unit 16c.

In the variation determining section 16c, based on the signal Vmax from the maximum value detecting section 16a and the signal Vmin from the minimum value detecting section 16b, each cell E in the assembled battery BA is determined.
ΔV which is the maximum deviation of the voltage between the terminals of Ci (= Vmax
−Vmin), and when the variation ΔV is equal to or more than a predetermined value, the discharge execution signal Kon is output. Therefore, the determination voltage Vref corresponding to the predetermined value for determination is input to the fluctuation determining unit 16c. In addition, the discharge execution signal Kon is output not only to the discharge switch operation unit 16e but also to the discharge switch operation unit 16e.
It is also output to the power supply control unit ECU.

The cell voltage variation detecting section 16d includes a number of differential amplifiers CM1, CM2,... Corresponding to the number i of cells.
・ ・ It has CMi. This cell voltage fluctuation detecting unit 1
The output of the minimum value detector 16b is commonly input to the minus terminal of each differential amplifier CM of FIG. 6d, and the cell voltage detection circuit 12 is connected to the plus terminal of each differential amplifier CMi.
Is input from each differential amplifier DAMi. Therefore, the unit cell variation detecting unit 16d calculates the voltages ΔV1, ΔV2,... Corresponding to the difference between the voltage of each unit cell ECi and the lowest voltage Vmin among the i unit cells.
ΔVi is output. That is, the cell variation detecting unit 16d
Detects the variation of the voltage of each cell as a variation voltage ΔVi which is a deviation from the minimum voltage Vmin. Each differential amplifier CM of the cell fluctuation detection unit 16d
Each output from i is output to the discharge switch operation unit 16e.

The discharge switch operation unit 16e includes, in addition to the i number of variation voltages ΔVi output from the unit cell voltage variation detection unit 16d, a discharge execution signal Kon and a reference voltage ΔVm output from the variation determination unit 16c. Is entered. When the discharge execution signal Kon is active, the discharge switch operation unit 16e executes the following processing. That is, each of the fluctuation voltages ΔV1, ΔV2,... ΔVi from the unit cell variation detection unit 16d is compared with the reference voltage ΔVm. Circuit 14
A signal for closing the discharge switch Ti is output.

In the power supply unit 125 of the first embodiment described above, the assembled battery BA mounted on the battery module SB is generated by the generator 100 via the power control circuit 130 as shown in FIG. The electric power is charged by the electric power, or the electric power is discharged through the power control circuit 130 to operate the electric motor 120. While repeating such charging / discharging, the battery pack control device 10 continues to control the charging / discharging state of the corresponding battery pack BA.
The variation in the voltage between the terminals of C, that is, i cells ECi
When the maximum deviation ΔV between the maximum value Vmax and the minimum value Vmin of the output voltage becomes larger than the determination voltage ΔVref, the discharge switch Ti of the cell discharge circuit 14 is turned on (closed), and the corresponding cell ECi To start discharging from. At this time, the switches Ti corresponding to all the cells ECi are not closed, but the variation voltage ΔVi, which is the deviation between the terminal voltage Vi and the minimum value Vmin, corresponds to the cell ECi larger than the reference voltage ΔVm. Switch T
Only i is closed.

This situation is shown in FIGS. 4A and 4B. In FIG. 4, for simplicity of explanation, the battery pack BA is assumed to be composed of four unit cells EC1, EC2, EC3, EC4. As shown in FIG. 4A, the four unit cells EC whose use has been started at the same voltage gradually have their terminal voltages V1, V2, V each time charge and discharge are repeated.
3 and V4, the deviation ΔV between the maximum value Vmax (= V3) and the minimum value Vmin (= V1) exceeds the determination value ΔVref at timing t1. At this time, the discharge execution signal Kon becomes active, and the variation voltage ΔVi, which is the deviation between the terminal voltage Vi and the minimum value Vmin, becomes:
The cell EC3 which is a cell larger than the reference voltage ΔVm
Since the corresponding switches T3 and T4 are closed, the EC4 starts discharging by a closed circuit passing through the discharge resistor Ri. As a result of discharging, these cells EC3, EC
4, the voltage between the terminals decreases. If the variation in the voltage between the terminals of each cell ECi becomes sufficiently small in this way, the discharge execution signal Kon becomes inactive, all the switches Ti are turned off (open state), and the cells EC3, EC3
The discharge from C4 is stopped. FIG. 4B shows a state of the voltage variation before and after the equalization processing by the discharge.

According to the present embodiment described above, it is possible to control the variation in the voltage between the terminals of the plurality of unit cells ECi within a predetermined range by using a simple hardware logic. Moreover, since such control can be performed in the battery module SB, not only can the load on the power supply control unit ECU managing the battery module SB be reduced, but also the wiring between the battery module SB and the power supply control unit ECU can be reduced. The reliability of the device can be improved. Further, in this embodiment, since the voltage between the terminals of each unit cell ECi is made uniform by discharging, it is not necessary to provide a charging device for each unit cell ECi, and the device configuration can be simplified.

In the above description, the discharge execution signal Ko
n has been described as being turned on / off by judging the magnitude of the judgment value Vref, but in practice, this judgment value Vref
Is provided with hysteresis. In a determination circuit using a comparator or the like, it is easy to provide hysteresis to the determination value Vref by subtracting the voltage of the discharge execution signal Kon, which is the determination result, from the determination value Vref.
With this configuration, once the discharge execution signal is turned on, the determination value Vref decreases by a predetermined value.
Even if the unit cell ECi having a high inter-terminal voltage is discharged and the deviation ΔV which is the maximum value of the inter-terminal voltage variation of the unit cell is reduced, the discharge is executed until the deviation ΔV becomes sufficiently small. The signal Kon is kept active.

Next, a second embodiment of the present invention will be described. In the second embodiment, the battery pack control device 10 is configured as a one-chip microcomputer instead of hardware logic. The one-chip microcomputer includes analog voltage input ports corresponding to the number of the single cells ECi, and can detect the terminal voltage Vi of each single cell ECi. The processing executed by the one-chip microcomputer of the battery pack control device 10 will be described with reference to the flowchart of FIG.

Although the processing shown in FIG. 5 is executed endlessly, the processing will be described from step S100 for the time being. In step S100, a process of inputting and detecting the voltages of the n unit cells ECi is performed. Next, the maximum value Vmax and the minimum value Vmin of the voltage are detected from the detected voltages Vi (step S102). From this detection result, the maximum voltage ΔVmax generated in the battery pack BA
(= Vmax−Vmin) (Step S10)
4) The ΔVmax is compared with a predetermined starting voltage Vref_on for starting a discharging process for eliminating voltage variations, and it is determined whether or not to execute a process for averaging the cells (step S106). . ΔVmax is the starting voltage V
If it is larger than ref_on, it is determined that the discharge process is to be performed, the discharge execution flag Kon is set to a value of 1, and until the condition is resolved.
This state is maintained (step 108).

Next, after confirming again that the discharge execution flag Kon has the value 1, the cell voltage variations ΔV1, ΔV2, ΔV3, based on the minimum cell voltage Vmin detected in step S102. , .DELTA.Vi is calculated (step S112). With the above processing, preparations for actually performing the discharge processing are completed.

Next, the actual discharge process is started. The conditions for terminating the discharge process are the cell voltage variations ΔV1, ΔV2.
.., The maximum variation ΔVmax
Is lower than a predetermined end voltage Vref_off. Here, the relationship between the start voltage Vref_on and the end voltage Vref_off will be described. As shown in FIG. 6, both of them are provided to provide a hysteresis to the ON / OFF of the flag Kon. That is, when it is determined whether or not to start the discharging process, the starting voltage Vref_on is compared with the starting voltage Vref_on. After it is determined that the discharging process is performed once (Kon ← 1), the end voltage Vref_off lower than the starting voltage is determined.
By comparing with, the end of the discharge process is determined. As a result, once the start of the discharge process is determined, the discharge process is continued until the variation in the voltage of each unit cell is reduced to some extent.

Therefore, in the next step S114, a process for individually determining whether or not the variation ΔVi of each cell voltage exceeds the end voltage is performed. That is, while the variable i is incremented sequentially, the determination of ΔVi> Vref_off is performed for the variation of the voltage of all the cells. As a result, a signal permitting discharge is output for the unit cell (cell) i determined as ΔVi> Vref_off (step S116). When a signal that allows discharge is output,
The switch Ti of the corresponding discharge circuit is closed, and the discharge of the corresponding cell i is started. This processing is shown as step S118 in FIG. Note that ΔVi ≦ Vref_of
No output of the discharge permission signal to the single cell discharging circuit 14 is performed for the single cell f, and the power of the single cell is maintained as it is (step S120). In the unit cell in which the discharge switch Ti of the unit cell discharge circuit 14 is closed in this manner, power is consumed through the discharge resistor Ri, and the unit cell voltage Vi decreases in accordance with the capacity-voltage characteristic. Become.

As described above, with respect to all the cells, the cell (cell) i whose voltage variation ΔVi exceeds the end voltage Vref_off is discharged, and as the voltage of the cells gradually decreases, the maximum voltage is reached. The variation ΔVmax gradually changes to a smaller value. Then, the value ΔVmax
Is repeated below until the value falls below the reference voltage Vref_off, and when ΔVmax <Vref_off (step S122), the discharge execution flag Kon is reset to low level (0) assuming that the equalization process is to be ended. (Step S124). As a result, the equalization process for eliminating the voltage variation of the unit cell ends (Step S
126).

According to the assembled battery control device 10 of the present embodiment that operates as described above, the maximum variation ΔV of the voltage of the assembled battery BA
When the value of max exceeds the reference voltage Vref_on, an equalization process for eliminating the variation in the voltage of the unit cells is started. By performing this process, the voltage value of each unit cell becomes the minimum value Vmin to (Vmin + Vref_off). Will be equalized. By equalizing the voltage values of the cells, the assembled battery BA can be stably used. That is, the battery pack control device 10 of the present embodiment
According to this, the voltage of the cells can be equalized using a simple closed circuit for discharging. For this reason, not only the reliability of the device is excellent, but also the size can be reduced, and the device can be configured integrally with the battery pack BA. Further, since the equalization process is independently executed by the battery pack control device 10, the management of the battery pack BA by the power supply control unit ECU is simplified, and the battery pack control is performed asynchronously with the charge / discharge control of the power supply unit 125. BA equalization processing can be performed.

In the above embodiment, hysteresis is provided at the start (Kon ← 1) and the end (Kon ← 0) of the discharge process, and this is shown in FIG. As shown in the drawing, in the present embodiment, the maximum variation ΔV
When the value of max becomes higher than the start voltage Vref_on, the discharge execution flag Kon is set to a high active state, and the maximum variation ΔVmax is lower than the start voltage Vref_on.
When the value falls below ref_off, the discharge execution flag Ko
n is inverted to low. As a result, the maximum variation ΔV
The output of the discharge execution flag Kon is prevented from frequently changing from high to low when the max is slightly different. This prevents the unit cell from being repeatedly discharged, and can extend the life of the battery pack BA.

In the two embodiments described above, it is possible to easily monitor whether or not the discharge process is being performed. In the first embodiment, the discharge execution signal Kon may be directly monitored. In the second embodiment, the value of the discharge execution flag Kon may be received from the battery pack control device 10. With this configuration, the power supply control unit ECU
It is possible to count the number of times the equalization process performed in A is performed, and it is possible to estimate the use state of the battery pack BA from this count value. That is, the power control unit E
The CU can manage the usage status of the assembled battery BA only by a simple counting process. The usage status of the battery pack BA estimated in this manner can be reported to the driver using a dedicated display unit or the like provided on the indicator panel of the electric vehicle or used for maintenance.
In this embodiment, the usage status of the battery pack BA is used as an indication of a replacement time due to deterioration. FIG. 7 shows an example of the display. In this example, a normal display is performed until the count value of the number of equalization processes n reaches the first reference value n1, a warning display is performed until the count value is equal to or more than n1 and the second reference value n2, and a third display is performed when the count value is n2 or more. Up to the reference value n3.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be implemented in various modes without departing from the gist of the present invention. Of course.

For example, in the above embodiment, the judgment value Vref,
The start voltage Vref_on, the end value Vref_off, and the like are fixed values. However, the values may be varied according to predetermined parameters, such as determining these values as a function of the temperature of the battery pack or the like. Further, the battery pack control device 10 of the present invention
Has been described as an example in which the present invention is applied to an electric vehicle, but the present invention can be easily applied to any other electric-driven moving body. For example, it can be used as a power source of a personal computer, a power source of a wireless device, a mobile phone, and the like.
Of course, the present invention can be used in fields other than the moving body, such as a power supply for an uninterruptible power supply.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a power supply unit employing a battery pack control device 10 according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram of the battery pack control device 10.

FIG. 3 is a schematic configuration diagram of the electric vehicle 1 on which the power supply unit 125 of the embodiment is mounted.

FIG. 4 is an explanatory diagram showing a state of a discharge process in the first embodiment.

FIG. 5 is a flowchart illustrating the contents of a discharge process in a second embodiment.

FIG. 6 is an explanatory diagram showing a start-end re-steresis operation of a discharge process.

FIG. 7 is an explanatory diagram of a display example of a deterioration state of the assembled battery BA executed by the power supply control unit ECU.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electric vehicle 10 ... Assembly battery control device 12 ... Single cell voltage detection circuit 14 ... Single cell discharge circuit 16 ... Single cell discharge control part 16a ... Maximum value detection part 16b ... Minimum value detection part 16c ... Variation judgment part 16d ... Single Battery variation detection unit 16e: Discharge switch operation unit 100: Generator 110: Gasoline engine 120: Electric motor 125: Power supply unit 130: Power control circuit 140: Wheels 150: Drive system BA: Battery pack BC: Battery pack management circuit CMi: Difference Dynamic amplifier DAMi: Differential amplifier ECU: Power supply control unit ECi: Single cell Ri: Discharge resistor SB: Battery module Ti: Discharge switch

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01M 10/44 H01M 10/44 PF term (Reference) 2G016 CA03 CB11 CB12 CC01 CC04 CC05 CC12 CC27 CD14 5G003 AA07 BA03 DA07 DA12 FA06 GC05 5H030 AA03 AA06 AA10 AS08 BB18 BB21 DD08 FF43 FF44 5H115 PA08 PG04 PG05 PG07 PG10 PI14 PI16 PI22 PI29 PU01 PU26 QN03 QN25 TI05 TI06 TI10 TO05 TR19 TU04 TU20 TZ07 UB05 UB08

Claims (9)

[Claims] 1. An assembled battery control device for controlling an electric energy of an assembled battery including a plurality of unit cells connected in series, comprising: a variation detecting unit configured to detect a variation in a voltage value of each of the plurality of unit cells. A cell discharging means for discharging any of the cells; and a cell discharging control for controlling the cell discharging means such that a variation in voltage value of the cells detected by the variation detecting means is within an allowable range. An assembled battery control device comprising a control unit. 2. The assembled battery control device according to claim 1, wherein the variation detecting means includes a single cell voltage detecting means for detecting a voltage value of each of the single cells, and An assembled battery control device which is means for detecting a variation in a voltage value based on a minimum value among detected cell voltages. 3. The unit cell discharge control unit has a predetermined range for an allowable value of unit cell variation, activates the operation of the unit cell discharge unit at the upper limit of the width, and sets the unit cell discharge unit at the lower limit of the width. 3. The battery pack control device according to claim 1, wherein the operation of the means is stopped. 4. The unit cell discharge control unit estimates a condition of the battery pack based on temporal information for controlling the unit cell discharge unit, and stops the operation of the unit cell discharge unit. The battery pack control device as described in the above. 5. The battery pack control device according to claim 1, wherein the unit cell discharging unit is provided for each of the unit cells, and a closed circuit is provided for each of the unit cells. An assembled battery control device, comprising: a resistor to be formed; and the unit cell discharge control means is a switch that is interposed in the closed circuit and switches on and off the circuit. 6. The battery pack control device according to claim 1, wherein the single battery is a lithium-based battery. 7. A method for controlling charging / discharging of a battery pack composed of a plurality of unit cells connected in series, comprising: detecting a variation in voltage value of each of the plurality of unit cells; A control method for, when a variation in battery voltage value falls outside an allowable range, specifying one or more unit cells from those having higher voltage values and discharging the specified unit cells. 8. An assembled battery comprising a plurality of cells,
A battery module comprising: a control device that controls a state of charge of the assembled battery, wherein the assembled battery is configured by connecting the plurality of cells in series, and the control device includes: A variation detecting means for detecting the variation of the voltage value of, and a single cell discharging means for discharging any of the single cells, so that the variation of the voltage value of the single cell detected by the variation detecting means is within an allowable range, A battery module comprising: a unit cell discharge control unit that controls the unit cell discharge unit. 9. An assembled battery comprising a plurality of cells,
An electric vehicle including: a control device that controls a state of charge of the battery pack; and an electric motor driven by the battery pack, wherein the battery pack is configured by connecting the plurality of cells in series, A control unit configured to detect a variation in voltage value of each of the plurality of unit cells; a unit cell discharging unit configured to discharge any of the unit cells; and a voltage value of the unit cell detected by the variation detecting unit. Cell discharge control means for controlling the cell discharge means so that the variation of the electric power is within an allowable range. The electric motor is driven by the electric power of the battery pack to output power to a vehicle drive shaft. vehicle.