JP2016220449A - Secondary battery system, and control method and program therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the output current rating of the whole system from decreasing after an abnormal battery is disconnected from the whole system.SOLUTION: A system comprising an abnormal cell detection part 110 which detects a secondary battery cell having abnormality in a battery pack having a plurality of secondary batteries connected in serial parallel, and a cell disconnection control part 102 which disconnects the secondary battery whose abnormality is detected from the battery pack has a current control part 109 which supplies electric power to the respective secondary batteries from the whose battery pack (excluding the abnormal cell 116), and further comprises a balancer 106 functioning as electric power supply means of supplying a current to the terminal to which the abnormal cell 116 is originally connected so that when the abnormal cell 116 is disconnected from the battery pack, an output current of the whole battery pack is equally output to all the constituent secondary batteries.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a secondary battery system, a control method thereof, and a program, and more particularly, to a battery including a means for separating abnormal battery cells from the system.

  In the lithium ion battery and the assembled battery constituted by the lithium ion battery, it is important to ensure its reliability. When an abnormality occurs in a battery constituting a battery system, it is desirable to make the abnormal battery independent from the system to reduce the influence on other batteries and not affect the operation of the subsequent system. .

  Therefore, in Patent Document 1, a series battery group in which a plurality of batteries are connected in series is connected to each series battery group in parallel in an assembled battery in which a plurality of series batteries are connected in parallel. A configuration in which a fuse is connected in series to a battery group and a current bypass circuit is described. With this configuration, when an abnormality occurs in the battery, the abnormality is detected, a large current is supplied to the current bypass circuit battery, and the fuse is blown to assemble a series battery group including the abnormal battery. Can be disconnected from the battery. By separating the abnormal battery at an early stage, the assembled battery can be composed of other batteries.

  However, in the technique disclosed in Patent Literature 1, when a normally operating battery is included in the separated abnormal battery, the remaining amount and output current (output power) cannot be used. There was a problem.

  Further, in the above configuration, the maximum current rating of the assembled battery before and after the battery is detached is reduced to (P-1) / P times when the parallel number of the batteries is P. This means that the maximum current rating of the assembled battery is determined by the parallel number regardless of the number of batteries of the assembled battery. That is, in an assembled battery configuration in which the number of parallel connections is small, there is a problem that the output current rating may be significantly reduced when the abnormal battery is disconnected.

  On the other hand, Patent Document 2 discloses a technique aimed at providing a battery equalization system with a reduced circuit scale when the number of battery cells in a battery pack increases. The technology of Patent Document 2 makes it easy to increase the number of battery cells in series by modularizing the direct control system of equalization control on a high voltage system board and arranging the main control CPU on the low voltage system board. It is possible to respond. However, even with the technique disclosed in Patent Document 2, there is a possibility that the problem that the output current is greatly reduced may remain.

  This invention is made | formed in view of the said situation, Comprising: It aims at suppressing the fall of the output current rating of the whole system after disconnecting an abnormal battery from the whole system.

In order to achieve the above object, the present invention provides:
An assembled battery in which a plurality of secondary batteries are connected in series and parallel;
An abnormal cell detector for detecting an abnormality of the secondary battery;
A cell shut-off control unit for separating the secondary battery in which an abnormality is detected from the assembled battery;
A current controller for supplying power to each secondary battery from the entire assembled battery;
When the secondary battery in which an abnormality was detected was disconnected from the assembled battery, the abnormality was detected and disconnected so that the output current of the entire assembled battery was evenly output by all of the secondary batteries constituting it. Power supply means for supplying current to the terminal to which the secondary battery was originally connected;
It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, the reduction | decrease of the output current rating of the whole system after disconnecting an abnormal battery from the whole system can be suppressed.

It is a circuit diagram which shows the structure of 1st Embodiment. In 1st Embodiment, it is the figure explaining the balance operation | movement when an abnormal cell is interrupted | blocked. In a 1st embodiment, it is a figure explaining the operation waveform of a balancer. It is a flowchart which shows operation | movement of the system of 1st Embodiment. It is a circuit diagram which shows the structure of 2nd Embodiment.

  An embodiment of the present invention disclosed below operates an assembled battery with a battery cell remaining after an abnormal battery cell is disconnected from the assembled battery in an assembled battery configured by connecting a plurality of battery cells in series and parallel. When it is made, it has the following features.

In short, power is supplied to the terminal to which the disconnected abnormal battery cell was originally connected so that the output power of the entire assembled battery is evenly output by all the battery cells constituting the battery. By providing this balance function, a reduction in the output current rating of the entire system is suppressed.
Hereinafter, this feature will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of the first embodiment of the present invention.
As shown in FIG. 1, the secondary battery system of the present embodiment generates a balance current corresponding to the load current of the battery unit 111 in which a plurality of battery cells 100 are connected in series and parallel (matrix shape). A balance unit 112 that detects the abnormality of the battery cell 100, and a cell cutoff control unit 102 that generates a selection signal for disconnecting the abnormal battery cell from the entire system.

  In FIG. 1, the secondary battery system of the present embodiment is connected to a DC power source 107 by a terminal 113 and a terminal 114.

  In the battery unit 111, a plurality of battery cells 100 are arranged and connected in series and parallel. In the figure, the battery cells 100 of the battery unit 111 are illustrated as three series and three parallel, but the number of series-parallel battery cells 100 is not limited to this. Each battery cell 100 is connected with a battery cell cutoff function 101 in series. The battery cell cutoff function 101 can selectively disconnect each battery cell from the system in response to a cutoff control signal from the cell cutoff control unit 102. The battery cell blocking function 102 can be realized by using, for example, a self-control protector (SC protector).

  The abnormal cell detection unit 110 uses the internal signal from the battery unit 111 to monitor whether the battery cells constituting the battery unit 111 are operating normally. The internal signal is, for example, the voltage, current, temperature, etc. of the battery cell. The abnormal cell detection unit 110 transmits abnormal battery cell information to the cell cutoff control unit 102.

  The abnormal cell detection unit 110 monitors the voltage of the battery cell and monitors the operation within a range where the battery cell does not exceed the charge / discharge end voltage. That is, the abnormal cell detection unit 110 has a so-called general battery protection function. This technique is a general operation and will not be described here.

  The cell cutoff control unit 102 generates a cutoff cell selection signal based on the abnormal battery cell information sent from the abnormal cell detection unit 110, and disconnects the abnormal battery cell from the system.

  The balance unit 112 includes a plurality of balancers 106, a current control unit 109, and a load current detection unit 108. The balancer 106 is provided in the number of battery cells in the battery unit 111 connected in series, and is connected in parallel with the series connection stage of the battery cells 100 in the battery unit 111.

  The balancer 106 includes a transformer 115, and the primary side is connected to the entire battery system (battery stack), and the secondary side is connected to a series connection stage of battery cells in the battery unit. Each of the primary side and secondary side paths includes a switching element 105 and a current detection unit 104. The current detection information of the primary side and secondary side current detection units 105 is sent to the current control unit 109. The load current detection unit 108 detects the load current of the entire battery system and sends detection information to the current control unit 109. The current control unit 109 uses the primary side and secondary side current detection information of the balancer 106 and the load current information of the load current detection unit 108 to turn ON / OFF the switching elements on the primary side and secondary side of the balancer 106. The timing signal is generated. The pulsating flow waveform on the secondary side of the balancer is smoothed by the smoothing filter 103.

FIG. 2 is a diagram illustrating a balance operation when an abnormal cell is blocked.
A method of equalizing the output current by the balance function in the discharge operation when the abnormal cell is disconnected from the system will be described.

  The abnormal cell 116 is temporarily in one of the first stages of the battery cells 111 connected in series. The abnormal battery cell is detected by the abnormal cell detector 110 and disconnected from the system by the cell shutoff controller 102. Suppose that At this time, in the balance unit 112, the balancer 106 connected to the terminal to which the abnormal cell 116 is originally connected operates. In FIG. 2, the balancer 106 not related to the balance operation is omitted for convenience of explanation.

  The battery system according to the present embodiment operates as described below in order to eliminate the imbalance between the capacity and the output current for each parallel stage that is generated when an abnormal cell is detected and disconnected from the system.

When the load current is IL, the primary current of the balancer 106 is IX, the number of series of the battery units 111 is s, and the number of parallels is p, the secondary current of the balancer 106 is s · IX.
The current control unit 109 sets the value of the balance current IX so that the output currents of the cells are equal. That is, when the balance current IX is set to IL · 1 / (ε · s · (p−1)) (where ε is the power conversion efficiency of the flyback converter), the output current of each battery cell is IL (Ε · s · p) / (ε · s · (p-1)) and equal current values in all cells.

  As shown in FIG. 2, assuming s = p = 3 and ε = 1, by setting IL · 1/8 as the primary current of the balancer 106, the secondary current of the balancer 106 becomes IL · 3/8, IL · 3/8 is applied as a current from the balancer 106 to the parallel stage from which the abnormal cell is disconnected.

  On the other hand, in the parallel stage (second stage and third stage) in which three normal cells are operating, the sum of the load current IL and the primary current IX of the balancer 106 is divided by the number of battery cells (IL + IX). / 3 will be passed by each battery cell, and now IX is set to IL · 1/8, the current value of each battery cell will be IL · 3/8, and the parallel stage (first stage) where abnormal cells are isolated ) Matches the current value of the battery cell.

  As described above, the imbalance of the parallel cells that occurs when the abnormal cell is disconnected from the system, the current value proportional to the load current flows as the balance current, assisting the shortage in the entire battery system, It becomes possible to output current values evenly from the battery cells.

  When no abnormal cell is detected, all the batteries are operating equally, and the current value at that time is IL / p. On the other hand, if the balancer is not used when the abnormal cell is disconnected from the system, the current value of the normal cell in the parallel stage where the abnormal cell is disconnected increases to IL · (p / (p−1)).

When the rate of change of the current value of the battery cell is compared before and after disconnecting the abnormal cell, the balancer is not used.
Use balancer p ^ 2 · 1 / ((p-1) / s) When ε = 1 The number of series s is an integer of 1 or more. The rate of increase in the current value is suppressed. Therefore, even when an abnormal cell is disconnected from the system by using the balancer 106, a significant increase in the output current of each battery can be suppressed. That is, it becomes possible to reduce the current margin of each battery cell prepared for the operation when the abnormal cell is disconnected.

FIG. 3 is a diagram for explaining operation waveforms of the balancer 106.
The abnormal cell is disconnected from the system by the cell cutoff control unit 102, and the balance unit 112 operates. The current control unit 109 has a number of series and parallel battery units in advance, and sets the primary current value IX of the balancer based on the load current detection result of the load current detection unit 108. The current control unit 110 turns on the primary side switching element until the primary current reaches IX. When the primary current reaches IX, the primary side switch is turned off and the secondary side switch is turned on. The secondary side switch is turned on until the secondary current becomes 0, and when it becomes 0, the secondary side switch is turned off and the primary side switch is turned on. By repeating this operation, an assist current is generated through the balancer.

FIG. 4 is a diagram illustrating a discharge flow of the battery system.
In FIG. 4, the secondary battery system of this embodiment performs normal charging / discharging operation when no abnormal battery cell is detected (S1). Next, the presence or absence of an abnormal cell is monitored by the abnormal cell detection unit 110 (S2). When an abnormal cell is detected, the cell cutoff control unit 102 disconnects the corresponding battery cell from the system (S3).

  If the battery system is being charged (S4 / No), the system is stopped and terminated. On the other hand, when the battery system is in a discharging operation (S4 / Yes), the balance unit 112 is operated, and the balance current according to the output load current is supplied to the parallel stage of the battery unit from which the abnormal cell is disconnected (S5). . The discharging operation is performed while the balance operation is performed, and the battery system is stopped when any of the cell voltages reaches the end voltage (S6 / Yes).

FIG. 5 is a circuit diagram showing a configuration of the second embodiment, which is a modification of the above embodiment.
FIG. 5 is different from the first embodiment shown in FIG. 1 in that the primary transformer of the balance unit 112 is shared, but the other components and operations are the same, so the description thereof is omitted. Even in the configuration as shown in FIG. 5, the same effects as those of the first embodiment described above can be obtained.

  Further, a secondary battery system in which a plurality of the secondary battery systems shown in FIG. 1 or the secondary battery system shown in FIG. 5 are connected in series (in a matrix) is configured. Is also preferable. In the case of this configuration, the capacity of the battery becomes large, and even with such a large capacity battery, it is possible to prevent a decrease in output power rating when the abnormal battery cell is disconnected.

  It is also preferable to implement a flyback converter between the power of the balance current supply. With this configuration, mounting can be simplified and high efficiency can be obtained.

  In addition, each procedure of the control method of the secondary battery system disclosed in the above-described embodiment may be executed by an embedded controller of the secondary battery system by a control program.

DESCRIPTION OF SYMBOLS 100 Battery cell 101 Battery cell cutoff function 102 Cell cutoff control part 103 Smoothing filter 104 Current detection part 105 Switching element 106 Balancer 107 DC power supply 108 Load current detection part 109 Current control part 110 Abnormal cell detection part 111 Battery part 112 Balance part 113 Terminal 114 Terminal 115 Transformer

JP 2002-142353 A JP 2013-223378 A

Claims (6)

An assembled battery in which a plurality of secondary batteries are connected in series and parallel;
An abnormal cell detector for detecting an abnormality of the secondary battery;
A cell shut-off control unit for separating the secondary battery in which an abnormality is detected from the assembled battery;
A current controller for supplying power to each secondary battery from the entire assembled battery;
When the secondary battery in which an abnormality was detected was disconnected from the assembled battery, the abnormality was detected and disconnected so that the output current of the entire assembled battery was evenly output by all of the secondary batteries constituting it. Power supply means for supplying current to the terminal to which the secondary battery was originally connected;
A secondary battery system comprising: The power supply means
When the secondary battery in which an abnormality is detected is disconnected from the assembled battery, the output current of the entire assembled battery is IL, the parallel number of the assembled batteries is P, the serial number of the assembled batteries is S, and the power supply means If the efficiency of ε is ε,
By setting the balance current from the entire assembled battery to IL × 1 / (ε × S × (P−1)), the separated two batteries are output so that all the secondary batteries are configured to output current evenly. The secondary battery system according to claim 1, wherein a current is supplied to a terminal to which the secondary battery was originally connected.   The secondary battery system according to claim 1, wherein a flyback converter is used as the power supply unit.   A secondary battery system comprising a plurality of the secondary battery systems according to any one of claims 1 to 3 connected in series and parallel. A control method executed by a secondary battery system including an assembled battery in which a plurality of secondary batteries are connected in series and parallel,
An abnormal cell detection step of detecting an abnormality of the secondary battery;
A cell shut-off control step of separating the secondary battery in which an abnormality is detected from the assembled battery;
A current control step of supplying power from the entire assembled battery to each secondary battery;
When the secondary battery in which an abnormality was detected was disconnected from the assembled battery, the abnormality was detected and disconnected so that the output current of the entire assembled battery was evenly output by all of the secondary batteries constituting it. A power supply process for supplying current to a terminal to which the secondary battery was originally connected;
A control method for a secondary battery system, comprising: In a built-in control device of a secondary battery system including an assembled battery in which a plurality of secondary batteries are connected in series and parallel,
An abnormal cell detection step of detecting an abnormality of the secondary battery;
A cell shut-off control step of separating the secondary battery in which an abnormality is detected from the assembled battery;
A current control step of supplying power from the entire assembled battery to each secondary battery;
When the secondary battery in which an abnormality was detected was disconnected from the assembled battery, the abnormality was detected and disconnected so that the output current of the entire assembled battery was evenly output by all of the secondary batteries constituting it. A power supply process for supplying current to a terminal to which the secondary battery was originally connected;
A control program for a secondary battery system, characterized in that

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