JP2018161000A - Charge control device and charge control method for battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge control device for a battery pack and a charge control method for the battery pack which make at least one of a first battery and a second battery chargeable even when abnormality occurs in any of a serial connection element, a first parallel switch and a second parallel switch.SOLUTION: There is provided a charge control device 10 for a battery pack 11 with a diode 16 which connects a first battery 12 with a second battery 13 in series, a first parallel switch 14 and a second parallel switch 15 which connect the first battery 12 with the second battery 13 in parallel; and a battery ECU 17 which controls the first parallel switch 14 and the second parallel switch 15, in which the battery ECU 17 controls at least one which can be turned on of the first parallel switch 14 and the second parallel switch 14 to be on to charge the battery pack when abnormality occurs in any of the diode 16, the first parallel switch 14 and the second parallel switch 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery pack charge control device and a charge control method.

  As a conventional technique of the battery pack charge control device and the charge control method, for example, a charger disclosed in Patent Document 1 can be cited. The charger of Patent Document 1 includes a series switch that connects a first battery and a second battery in series, a first parallel switch that is connected in parallel with a series connection circuit of the series switch and the first battery, and a series switch. And a second parallel switch connected in parallel to the series connection circuit with the second battery. A control part controls a series switch, a 1st parallel switch, and a 2nd parallel switch to on / off, and charges a battery. Therefore, according to the charger, three switches can be switched to connect two batteries in series and charge with the same current, or only one battery can be selected and charged.

JP 2005-143221 A

  However, in the charger disclosed in Patent Document 1, if an open failure occurs in the series switch, or if an open failure or a short-circuit failure occurs in one of the first parallel switch and the second parallel switch, the first battery and Charging by series connection of the second battery becomes impossible. For example, when an open failure occurs in one of the first parallel switch and the second parallel switch, the first battery or the second battery cannot be discharged, and when one of the batteries cannot be discharged, the battery is charged by series connection. Sometimes a battery that cannot be discharged becomes fully charged and cannot be charged. When either one of the first parallel switch and the second parallel switch is short-circuited, the first battery and the second battery are not connected in series. When an open failure occurs in the series switch, the first battery and the second battery cannot be charged in series connection, and the first battery and the second battery cannot be charged in series connection.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a first battery and a second battery even if an abnormality occurs in any of the series connection element, the first parallel switch, and the second parallel switch. The present invention provides a battery pack charge control device and a battery pack charge control method that can charge at least one of the above.

  In order to solve the above problems, the present invention provides a series connection element that connects a first battery and a second battery in series, a series connection to the second battery, the first battery and the series connection element, A first parallel switch connected in parallel with the series connection circuit, a second parallel switch connected in series with the first battery, and connected in parallel with a series connection circuit of the series connection element and the second battery, A switch control unit that controls the first parallel switch and the second parallel switch, wherein the switch control unit controls the first parallel switch and the second parallel switch to be off at the time of charging, and at the time of discharging. A battery pack charge control device for controlling each of the first parallel switch and the second parallel switch to be ON, wherein the series connection element, the short circuit failure of the series connection element is excluded. When an abnormality occurs in one of the parallel switch and the second parallel switch, the switch control unit charges and turns on at least one of the first parallel switch and the second parallel switch that can be turned on. It is characterized by that.

  In the present invention, when an abnormality occurs in any of the series connection element, the first parallel switch, and the second parallel switch, at least one of the first parallel switch and the second parallel switch that is turned on is turned on by the switch control device. Be controlled. For this reason, at least one of the first battery and the second battery is connected in a chargeable manner, and charging is possible. However, any abnormality of the series connection element, the first parallel switch, and the second parallel switch is any one of the open connection short circuit of the series connection element, the first parallel switch, and the second parallel switch, excluding the short circuit failure of the series connection element. Indicates a short-circuit failure or open-circuit failure.

In the battery pack charge control device, the abnormality is an open failure of one of the first parallel switch and the second parallel switch, and the switch control unit includes the first parallel switch and the first parallel switch. It is good also as a structure which charges the said 1st battery or said 2nd battery which can be charged by controlling any other of 2nd parallel switch to ON.
In this case, even if one of the first parallel switch and the second parallel switch is open-failed, the other of the first parallel switch and the second parallel switch is controlled to be turned on. The battery can be charged.

In the battery pack charge control device, the abnormality is a short-circuit failure of one of the first parallel switch and the second parallel switch, and the switch control unit includes the first parallel switch and the first parallel switch. A configuration may be adopted in which one of the second parallel switches is turned on to charge the first battery and the second battery.
In this case, even if either one of the first parallel switch and the second parallel switch is short-circuited, the other of the first parallel switch and the second parallel switch is controlled to be turned on. The batteries are connected in parallel and can charge the first battery and the second battery.

In the battery pack charging control apparatus, the abnormality is an open failure of the series connection element, and the switch control unit controls the first parallel switch and the second parallel switch to turn on, and The first battery and the second battery may be charged.
In this case, since the first parallel switch and the second parallel switch are turned on even if the circuit element has an open failure, the first battery and the second battery are connected in parallel, and the first battery and the second battery can be charged.

In the battery pack charge control device, the series connection element may be a diode.
In this case, the first battery and the second battery are not discharged to the load while being connected in series. Even if the battery pack is externally short-circuited for some reason, the first battery and the second battery are not energized in the direction in which they are discharged in a state of being connected in series.

  Moreover, this invention is connected in series with the serial connection element which connects a 1st battery and a 2nd battery in series, the serial connection to the said 2nd battery, and the said 1st battery and the said serial connection element. A first parallel switch connected in series with the first battery, connected in parallel with a series connection circuit of the series connection element and the second battery, the first parallel switch and the first A switch control unit that controls two parallel switches, wherein the switch control unit controls the first parallel switch and the second parallel switch to be turned off during charging, and the first parallel switch and the second parallel switch during discharging. A battery pack charge control method for controlling each of the second parallel switches to be turned on, wherein the series connection element, the first parallel switch, and the front of the series connection element are excluded. When an abnormality occurs in any one of the second parallel switches, the switch control unit charges and charges at least one of the first parallel switch and the second parallel switch that can be turned on. To do.

  In the present invention, when an abnormality occurs in any one of the circuit element, the first parallel switch, and the second parallel switch, at least one of the first parallel switch and the second parallel switch that is turned on is controlled to be turned on by the switch control device. Is done. For this reason, at least one of the first battery and the second battery is connected in a chargeable manner, and charging is possible.

  According to the present invention, a battery pack charge control device and a battery that can charge at least one of the first battery and the second battery even if an abnormality occurs in any of the circuit element, the first parallel switch, and the second parallel switch. A charge control method for the pack can be provided.

It is a figure which shows an example of the charge control apparatus of the battery pack which concerns on 1st Embodiment. It is a flowchart which shows the procedure of failure determination. (A) is a figure which shows the state charged in series at the time of normal, (b) is a figure which shows the state at the time of discharge to the load at the time of normal. (A) It is a figure which shows the state at the time of charge in the open failure of a 1st parallel switch, (b) is a figure which shows the state at the time of discharge to the load in the open failure of a 1st parallel switch. (A) is a figure which shows the state at the time of charge in the open circuit failure of a diode, (b) is a figure which shows the state at the time of discharge to the load in the open circuit failure of a diode. (A) is a figure which shows the state at the time of the charge in the short circuit failure of a 1st parallel switch, (b) is a figure which shows the state at the time of the discharge to the load in the short circuit failure of a 1st parallel switch. It is a figure which shows an example of the charge control apparatus of the battery pack which concerns on 2nd Embodiment. (A) is a figure which shows the state at the time of charge in the open failure of a series switch, (b) is a figure which shows the state at the time of discharge to the load in the open failure of a series switch.

(First embodiment)
Hereinafter, a battery pack charge control device (hereinafter referred to as a “charge control device”) according to a first embodiment will be described with reference to the drawings. An example of a circuit by connecting a load, a battery, and a charger to which the charge control device according to the present embodiment is applied will be described.

  A charge control device 10 shown in FIG. 1 is mounted on a vehicle such as an electric forklift, for example, and controls charging of the battery pack 11. As shown in FIG. 1, the battery pack 11 includes a first battery 12, a second battery 13, a first parallel switch 14, a second parallel switch 15, a diode 16, and a battery ECU (Electronic Control Unit) 17. It is equipped with.

  The first battery 12 and the second battery 13 are assembled batteries in which a plurality of battery cells are connected in series, and the battery cells are lithium ion secondary batteries. The first battery 12 and the second battery 13 are connected in parallel to each other. The connection point A is a connection point on the positive side of the first battery 12 and the second battery 13, and the connection point B is a connection point on the negative side of the first battery 12 and the second battery 13.

  The diode 16 corresponds to a series connection element that connects the first battery 12 and the second battery 13 in series. The anode side of the diode 16 is connected to the negative side of the first battery 12, and the cathode side of the diode 16 is connected to the positive side of the second battery 13. Therefore, the diode 16 passes a current from the first battery 12 toward the second battery 13 and blocks a current from the second battery 13 toward the first battery 12. The connection point C is a connection point between the negative electrode side of the first battery 12 and the anode side of the diode 16. The connection point D is a connection point between the positive electrode side of the second battery 13 and the cathode side of the diode 16.

  The first parallel switch 14 is connected to a first series connection circuit (a circuit between the contacts ACD) in which the first battery 12 and the diode 16 are connected in series to be connected in parallel to the positive side of the second battery 13 (between the contacts AD). : Between the positive electrode of the first battery 12 and the connection point D). The second parallel switch 15 is connected to a negative side (contact CB) of the first battery 12 so as to be connected in parallel with a second series connection circuit (circuit between the contacts CDB) in which the diode 16 and the second battery 13 are connected in series. (Between the connection point C and the negative electrode of the second battery 13). The first parallel switch 14 and the second parallel switch 15 are ON / OFF controlled by the battery ECU 17 and are switches for switching the first battery 12 and the second battery 13 from the serial connection to the parallel connection. When the first parallel switch 14 and the second parallel switch 15 are turned on, the first battery 12 and the second battery 13 are connected in parallel. The first parallel switch 14 and the second parallel switch 15 may use a semiconductor relay in addition to a mechanical relay.

  On the negative electrode side (between the contact points AC) of the first battery 12, a first current detection unit 18 that detects a current flowing through the first battery 12 is provided. A second current detection unit 19 that detects a current flowing through the second battery 13 is provided on the negative electrode side (between the contacts DB) of the second battery 13.

  The first battery 12 and the second battery 13 are connected to the load 20 via the main switch 21. The main switch 21 is provided between a connection point A on the positive electrode side of the first battery 12 with the second battery 13 and the load 20 and is on / off controlled by the battery ECU 17. The load 20 is an inverter that converts the electric power supplied from the first battery 12 and the second battery 13 connected in parallel into an alternating current and outputs the alternating current, and a traveling motor that is driven by the electric power output from the inverter. The vehicle travels by driving the travel motor.

  When the first battery 12 and the second battery 13 and the load 20 are electrically connected by the main switch 21, power is supplied from the first battery 12 and the second battery 13 to the load 20. When the main switch 21 electrically disconnects the first battery 12 and the second battery 13 and the load 20, power supply from the first battery 12 and the second battery 13 to the load 20 is cut off.

  The first battery 12 and the second battery 13 can be connected to the charger 22 via a connector (not shown). The first battery 12 and the second battery 13 are charged with electric power supplied via the charging switch 23 of the charger 22. The charger 22 supplies electric power for charging to the first battery 12 and the second battery 13 using electric power supplied from an external power source such as a commercial power source. The charging switch 23 is ON / OFF controlled by the battery ECU 17 when the charger 22 is connected to the first battery 12 and the second battery 13.

  When the charger 22 is electrically connected to the first battery 12 and the second battery 13 by the charging switch 23 when power is output from the charger 22, the first battery 12, Electric power is supplied to the two batteries 13. When the charger 22 is electrically disconnected from the first battery 12 and the second battery 13 by the charge switch 23, power supply from the charger 22 to the first battery 12 and the second battery 13 is cut off.

  The battery ECU 17 corresponds to a switch control unit that controls on / off of the first parallel switch 14, the second parallel switch 15, the charging switch 23, and the main switch 21. The battery ECU 17 controls the first parallel switch 14 and the second parallel switch 15 to be off during charging when there is no abnormality. When the first parallel switch 14 and the second parallel switch 15 are controlled to be turned off, the first battery 12 and the second battery 13 are charged by series connection. On the other hand, the battery ECU 17 controls the first parallel switch 14 and the second parallel switch 15 to be on during discharging. When the first parallel switch 14 and the second parallel switch 15 are turned on, the first battery 12 and the second battery 13 are discharged by parallel connection.

  The battery ECU 17 outputs a current command value for charging to the charger 22. Further, the battery ECU 17 detects the charging rate of the first battery 12 and the second battery 13 and outputs a charge stop command to the charger 22 when the battery is fully charged. Further, the battery ECU 17 receives detection signals of current values detected by the first current detection unit 18 and the second current detection unit 19. The battery ECU 17 determines whether the first parallel switch 14 and the second parallel switch 15 are abnormal (open failure or short-circuit failure) based on the current value signals detected by the first current detection unit 18 and the second current detection unit 19. An abnormality (open failure) of the diode 16 is detected. Note that an open failure is a failure in an open state where current cannot be supplied, and a short-circuit failure is a failure in a short-circuit state where power supply cannot be interrupted.

  The battery ECU 17 detects an abnormality in the first parallel switch 14 and the second parallel switch 15 based on the current values detected by the first current detection unit 18 and the second current detection unit 19 by executing a preset failure determination program. And the abnormality of the diode 16 is determined. As shown in FIG. 2, in the failure determination program including a series of steps (S01 to S14), an abnormality in the first parallel switch 14 and the second parallel switch 15 and an abnormality in the diode 16 are detected at the time of discharging and before charging. Determine. Then, the battery ECU 17 controls on / off of the first parallel switch 14 and the second parallel switch 15 based on signals of current values detected by the first current detection unit 18 and the second current detection unit 19. If the battery ECU 17 determines that the first parallel switch 14 and the second parallel switch 15 have an open failure or a short-circuit failure, or the diode 16 has an open failure, the battery ECU 17 determines that the first parallel switch 14 and the second parallel switch 15 At least one of the two parallel switches 15 that can be turned on during charging is controlled to be turned on.

  The series of steps (S01 to S14) of the failure determination program will be described. First, during discharge to the load 20 by the parallel connection of the first battery 12 and the second battery 13 (see step S01), the battery ECU 17 It is determined whether or not the current value of the 1 current detector 18 or the second current detector 19 is 0 (see step S02). When it is determined that the current value of the first current detection unit 18 or the second current detection unit 19 is 0, the battery ECU 17 determines that the first parallel switch 14 or the second parallel switch 15 is an open failure (see step S03). ). After the determination of the open failure, the discharge is terminated (see step S04). Next, the battery ECU 17 performs charging by turning on one of the first parallel switch 14 and the second parallel switch 15 that can be turned on during charging (see step S05).

  At this time, one of the first battery 12 and the second battery 13 connected in series with one of the first parallel switch 14 and the second parallel switch 15 that can be turned on is charged. Of the first parallel switch 14 and the second parallel switch 15, the other of the first battery 12 and the second battery 13 connected in series with the other of the open failure is not charged.

  If it is determined in step S02 that the current value of the first current detector 18 or the second current detector 19 is not 0, the first battery 12 and the second battery 13 are connected in series after the discharge to the load 20 is completed. A charge check is performed in a state of being performed (see step S06). Next, the battery ECU 17 determines whether or not the current values of the first current detection unit 18 and the second current detection unit 19 are 0 (see step S07). When it is determined that the current values of the first current detector 18 and the second current detector 19 are both 0, the battery ECU 17 determines that the diode 16 is open (see step S08). Next, the battery ECU 17 turns on the first parallel switch 14 and the second parallel switch 15 to perform charging (see step S09).

  At this time, the first battery 12 and the second battery 13 are connected in parallel, and the first battery 12 and the second battery 13 are charged simultaneously.

  If it is determined in step S07 that the current values of the first current detector 18 and the second current detector 19 are not 0, the battery ECU 17 determines that the current value of the first current detector 18 or the second current detector 19 is 0. It is determined whether or not there is (see step S10). When it is determined that the current value of the first current detection unit 18 or the second current detection unit 19 is 0, the battery ECU 17 determines that the first parallel switch 14 or the second parallel switch 15 is short-circuited (see step S11). ). Next, the battery ECU 17 performs charging by turning on one of the first parallel switch 14 and the second parallel switch 15 that can be turned on during charging (see step S12).

  At this time, the first battery 12 and the second battery 13 are connected in parallel, and the first battery 12 and the second battery 13 are charged simultaneously.

  Next, when it is determined in step S10 that the current value of the first current detector 18 or the second current detector 19 is not 0, the battery ECU 17 determines that there is no abnormality (see step S13). Next, serial connection charging is performed (step S14). At this time, the 1st battery 12 and the 2nd battery 13 are charged in the state of series connection. In addition, about step S06-S14, it repeats not only during the check before the charge by series connection but during the charge by series connection.

Next, a charge control method by the charge control device 10 will be described.
In the present embodiment, in a normal state where the first parallel switch 14, the second parallel switch 15, and the diode 16 are normal, the first battery 12 and the second battery 13 are charged in a series connection state, and the first battery 12 The second battery 13 is discharged in a state of being connected in parallel. Specifically, as shown in FIG. 3A, at the time of charging, the first parallel switch 14 and the second parallel switch 15 are controlled to be off, and the first battery 12 and the second battery 13 are connected in series. Charged in state. As shown in FIG. 3B, at the time of discharging, the first parallel switch 14 and the second parallel switch 15 are respectively controlled to be on, and the first battery 12 and the second battery 13 are discharged in a state of being connected in parallel. .

  Next, the charge control method in the case of each abnormality of the abnormality (opening failure or welding failure) of the first parallel switch 14 or the second parallel switch 15 and the abnormality (opening failure) of the diode 16 will be described. In the present embodiment, when an abnormality occurs in any of the first parallel switch 14, the second parallel switch 15, and the diode 16, the charging control device 10 can be turned on among the first parallel switch 14 and the second parallel switch 15. At least one of them is turned on for charging.

<Opening Failure of First Parallel Switch 14 (or Second Parallel Switch 15)>
When the first parallel switch 14 has an open failure, the current value detection signal of the second current detection unit 19 indicates a current value of 0 when discharging in parallel connection. For this reason, the battery ECU 17 determines that the first parallel switch 14 has an open failure. When the first parallel switch 14 has an open failure, the second battery 13 cannot be discharged. Therefore, even if the first battery 12 and the second battery 13 are connected in series and charged, the second battery 13 that cannot be discharged is immediately charged by the battery ECU 17 so that the first battery 12 is not charged. . Therefore, in this embodiment, as shown in FIG. 4A, when the first parallel switch 14 is in an open failure, the battery ECU 17 controls the first parallel switch 15 that can be turned on during charging to turn on the first parallel switch 15. The battery 12 is charged. When the second parallel switch 15 is controlled to be turned on, the first battery 12 can be charged. Charging and discharging of the second battery 13 is impossible, and the battery capacity of the battery pack 11 is halved. However, as shown in FIG. Discharging is possible.

  Although not shown, when the second parallel switch 15 has an open failure, the detection signal of the current value of the first current detection unit 18 indicates a current value of 0 when discharging in parallel connection. For this reason, charging and discharging of the first battery 12 are impossible. In this case, the battery ECU 17 charges the second battery 13 by controlling the first parallel switch 14 to be on during charging. When the first parallel switch 14 is controlled to be on, the second battery 13 can be charged. In this case as well, the battery capacity of the battery pack 11 is halved, but the load 20 can be discharged by the power charged in the second battery 13.

  As described above, when the first parallel switch 14 or the second parallel switch 15 has an open failure, at least one of the first parallel switch 14 and the second parallel switch 15 that can be turned on is controlled to be turned on. And any one of the 1st battery 12 and the 2nd battery 13 currently connected in series with the one which can be turned on among the 1st parallel switch 14 and the 2nd parallel switch 15 is charged. Of the first parallel switch 14 and the second parallel switch 15, one of the first battery 12 and the second battery 13 connected in series with the other that is open-failed is not charged.

<Opening failure of diode 16>
In the case of an open circuit failure of the diode 16, even if the detection signals of the current values of the first current detection unit 18 and the second current detection unit 19 are normal during discharging, the first current detection unit 18 and the first current detection unit during charging in series connection 2 The current value detection signals of the current detector 19 each indicate a current value of 0. For this reason, the battery ECU 17 determines that an open failure of the diode 16 occurs. Therefore, in the present embodiment, as shown in FIG. 5A, the battery ECU 17 controls the first parallel switch 14 and the second parallel switch 15 to be on, and the first battery 12 and the second battery connected in parallel. 13 is charged. In the open failure of the diode 16, the first battery 12 and the second battery 13 cannot be charged in series connection, but the first parallel switch 14 and the second parallel switch 15 are controlled to be turned on. The battery 12 and the second battery 13 are connected in parallel and can be charged. Further, as shown in FIG. 5B, discharge in parallel connection to the load 20 is possible by the electric power charged in the first battery 12 and the second battery 13.

  Thus, when the diode 16 has an open failure, the first parallel switch 14 and the second parallel switch 15 are turned on, and the first battery 12 and the second battery 13 are connected in parallel. Then, both the first battery 12 and the second battery 13 connected in parallel are charged.

<Short-circuit fault of the first parallel switch 14 (or the second parallel switch 15)>
In the case of a short circuit failure (welding) of the first parallel switch 14, the battery ECU 17 does not indicate an appropriate current value because the detection signal of the current value of the first current detection unit 18 does not indicate an appropriate current value when checking before charging in series connection. It is determined that one parallel switch 14 is short-circuited. As shown in FIG. 6 (a), the battery ECU 17 charges the first battery 12 and the second battery 13 connected in parallel by controlling the second parallel switch 15 to be on during charging. When the first parallel switch 14 is short-circuited, the first battery 12 and the second battery 13 cannot be charged in series, but the first battery 12 is controlled by turning on the second parallel switch 15. The second battery 13 is connected in parallel and can be charged. Moreover, as shown in FIG.6 (b), the discharge by the parallel connection with respect to the load 20 with the electric power charged by the 1st battery 12 and the 2nd battery 13 is attained.

  Although not shown, when the second parallel switch 15 is short-circuited (welded), the first parallel switch 14 is controlled to be turned on during charging. Although the first battery 12 and the second battery 13 cannot be charged in series connection, the first battery 12 and the second battery 13 are connected in parallel and charged by the first parallel switch 14 being turned on. Is possible. Also in this case, discharge in parallel connection to the load 20 is possible by the electric power charged in the first battery 12 and the second battery 13.

  Thus, when the first parallel switch 14 or the second parallel switch 15 is short-circuited, at least one of the first parallel switch 14 and the second parallel switch 15 that can be turned on is turned on, and the first battery 12 and the second battery 12 are turned on. The batteries 13 are connected in parallel. Then, both the first battery 12 and the second battery 13 connected in parallel are charged.

  In addition, when the first parallel switch 14 and the second parallel switch 15 each have an open failure, charging in series is possible, but either discharging in parallel connection or any of the first battery 12 or the second battery 13 is possible. Discharging due to is impossible. In addition, when the first parallel switch 14 and the second parallel switch 15 are short-circuited respectively, charging by series connection is impossible, but the first parallel switch 14 and the second parallel switch 15 are not controlled without being controlled. Charging and discharging by connection is possible.

According to this embodiment, there exist the following effects.
(1) When an abnormality occurs in any of the diode 16, the first parallel switch 14, and the second parallel switch 15, at least one of the first parallel switch 14 and the second parallel switch 15 that can be turned on is turned on by the battery ECU 17. Controlled. For this reason, at least one of the 1st battery 12 and the 2nd battery 13 is connected so that charging is possible, and charging becomes possible.

(2) Even if either one of the first parallel switch 14 and the second parallel switch 15 is open-circuited, the other of the first parallel switch 14 and the second parallel switch 15 is controlled to be turned on. The battery 12 or the second battery 13 can be charged.

(3) Even if one of the first parallel switch 14 and the second parallel switch 15 is short-circuited, the other of the first parallel switch 14 and the second parallel switch 15 is controlled to be turned on. The battery 12 and the second battery 13 are connected in parallel and can be charged.

(4) Since the first parallel switch 14 and the second parallel switch 15 are controlled to be turned on even when the diode 16 is in an open failure, the first battery 12 and the second battery 13 can be connected in parallel and charged. .

(5) Although the diode 16 is used as a series connection element for connecting the first battery 12 and the second battery 13 in series, the diode 16 is a direction in which the power of the first battery 12 and the second battery 13 connected in series is discharged. It is provided in a direction to block the current to For this reason, the high voltage power of the first battery 12 and the second battery 13 connected in series is not discharged to the load 20. Even if any external short circuit occurs at the connector of the battery pack 11, the power of the first battery 12 and the second battery 13 connected in series is not discharged to the load 20.

(Second Embodiment)
Next, a battery pack charge control device and a battery pack charge control method according to the second embodiment will be described. This embodiment is different from the first embodiment in that a series connection element is a switch instead of a diode.

  As shown in FIG. 7, in the charging control device 30, a series switch 31 as a series connection element connects the first battery 12 and the second battery 13 in series. The series switch 31 is a normally open contact controlled by the battery ECU 17 to be turned on and off, and a semiconductor relay may be used in addition to a mechanical relay. When charging the first battery 12 and the second battery 13 by the series connection, the series switch 31 is controlled to be on. On the other hand, when the first battery 12 and the second battery 13 are connected in parallel and discharged, the series switch 31 is controlled to be off.

  When the series switch 31 fails to open, the first battery 12 and the second battery 13 cannot be charged by series connection. An open failure of the series switch 31 is caused when the first parallel switch 14 and the second parallel switch 15 are controlled to be turned off, and the first current detector 18 and the second battery 13 connected in series are charged. It is determined when the current value of the second current detector 19 becomes zero. As shown in FIG. 8A, when the series switch 31 has an open failure, the first parallel switch 14 and the second parallel switch 15 are controlled to be turned on, and the first battery 12 and the second battery 13 are connected in parallel. Then, both the first battery 12 and the second battery 13 connected in parallel are charged. Further, as shown in FIG. 8B, discharging in parallel connection to the load 20 is possible by the electric power charged in the first battery 12 and the second battery 13.

  This embodiment has the same effects as the effects (1) to (4) of the first embodiment. Further, according to the present embodiment, the series switch 31 can be used instead of the diode.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist of the invention. For example, the following modifications may be made.

In the above embodiment, the battery pack is mounted on a vehicle such as an electric forklift, and the charge control device controls the discharge of the battery pack in addition to controlling the charging of the battery pack. It is not limited. Moreover, although the 1st battery and the 2nd battery were set as the assembled battery in which the some battery cell was connected in series, the structure which has a single battery cell may be sufficient. The battery cell is not limited to a lithium ion secondary battery, but may be a nickel hydride secondary battery or a lead storage battery.
In the above embodiment, the charging switch is provided in the charger, but the charging switch may be provided in the battery pack.

DESCRIPTION OF SYMBOLS 10 Charge control apparatus 11 Battery pack 12 1st battery 13 2nd battery 14 1st parallel switch 15 2nd parallel switch 16 Diode (as a serial connection element)
17 Battery ECU (as switch control unit)
18 First current detector 19 Second current detector 20 Load 21 Main switch 22 Charger 23 Charge switch A, B, C, D Contact

Claims (6)

A series connection element for connecting the first battery and the second battery in series;
A first parallel switch connected in series to the second battery and connected in parallel with a series connection circuit of the first battery and the series connection element;
A second parallel switch connected in series to the first battery and connected in parallel to a series connection circuit of the series connection element and the second battery;
A switch control unit for controlling the first parallel switch and the second parallel switch,
The switch control unit
When charging, the first parallel switch and the second parallel switch are controlled to be off,
A battery pack charge control device that controls each of the first parallel switch and the second parallel switch to be turned on at the time of discharging,
When an abnormality occurs in any of the series connection element, the first parallel switch, and the second parallel switch, excluding a short circuit failure of the series connection element,
The switch control unit
A charge control device for a battery pack, wherein at least one of the first parallel switch and the second parallel switch that is turned on is turned on for charging. The abnormality is an open failure of one of the first parallel switch and the second parallel switch,
The switch control unit charges the first battery or the second battery that can be charged by controlling one of the first parallel switch and the second parallel switch to be on. The charge control apparatus of the battery pack of description. The abnormality is a short-circuit fault of one of the first parallel switch and the second parallel switch,
2. The battery according to claim 1, wherein the switch control unit turns on one of the first parallel switch and the second parallel switch to charge the first battery and the second battery. 3. Pack charge control device. The abnormality is an open failure of the series connection element,
2. The battery pack charge control according to claim 1, wherein the switch control unit turns on the first parallel switch and the second parallel switch to charge the first battery and the second battery. 3. apparatus.   The battery pack charge control device according to claim 1, wherein the series connection element is a diode. A series connection element for connecting the first battery and the second battery in series;
A first parallel switch connected in series to the second battery and connected in parallel with a series connection circuit of the first battery and the series connection element;
A second parallel switch connected in series to the first battery and connected in parallel to a series connection circuit of the series connection element and the second battery;
A switch control unit for controlling the first parallel switch and the second parallel switch,
The switch control unit
When charging, the first parallel switch and the second parallel switch are controlled to be off,
A battery pack charge control method for controlling each of the first parallel switch and the second parallel switch to be turned on at the time of discharging,
When an abnormality occurs in any of the series connection element, the first parallel switch, and the second parallel switch, excluding a short circuit failure of the series connection element,
The switch control unit
A charge control method for a battery pack, wherein charging is performed by controlling at least one of the first parallel switch and the second parallel switch to be turned on.

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