JP6787208B2 - Battery pack charge control device and charge control method - Google Patents

Description

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

As a conventional technique of the charge control device and the charge control method of the battery pack, for example, the charger disclosed in Patent Document 1 can be mentioned. The charger of Patent Document 1 includes a series switch that connects the first battery and the second battery in series, a first parallel switch that is connected in parallel with the series connection circuit of the series switch and the first battery, and a series switch. It includes a second parallel switch that is connected in parallel to the series connection circuit with the second battery. The control unit controls the series switch, the first parallel switch, and the second parallel switch on and off to charge the 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.

Japanese Unexamined Patent Publication No. 2005-143221

However, in the charger disclosed in Patent Document 1, if an open failure occurs in the series switch, or an open failure or a short circuit failure occurs in either the first parallel switch or the second parallel switch, the first battery and the charger Charging by connecting the second battery in series becomes impossible. For example, when either the first parallel switch or the second parallel switch has an open failure, the first battery or the second battery cannot be discharged, and when one of the batteries cannot be discharged, charging by series connection is performed. Occasionally, a non-dischargeable battery quickly becomes fully charged and cannot be charged. If either the first parallel switch or the second parallel switch fails due to a short circuit, the series connection of the first battery and the second battery cannot be established. When an open failure occurs in the series switch, the first battery and the second battery cannot be charged by the series connection, and the first battery and the second battery cannot be charged by the series connection.

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

In order to solve the above problems, the present invention comprises a series connection element that connects a first battery and a second battery in series, and a series connection element that is connected in series to the second battery and that is connected to the first battery and the series connection element. A first parallel switch connected in parallel with the series connection circuit of the above, a second parallel switch connected in series with the first battery and connected in parallel with the series connection circuit of the series connection element and the second battery, and the above. A switch control unit for controlling the first parallel switch and the second parallel switch is provided, and 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. , The battery pack charge control device that controls the first parallel switch and the second parallel switch to be turned on, respectively, excluding the short-circuit failure of the series connection element, the series connection element, the first parallel switch, and the said. When an abnormality occurs in any of the second parallel switches, the switch control unit is characterized in that at least one of the first parallel switch and the second parallel switch that can be turned on is controlled to be turned on and charged. To do.

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 can be turned on is turned on by the switch control device. Be controlled. Therefore, at least one of the first battery and the second battery is rechargeably connected and can be charged. However, any abnormality of the series connection element, the first parallel switch, or the second parallel switch is any of the open short circuit of the series connection element, the first parallel switch, and the second parallel switch, except for the short circuit failure of the series connection element. Refers to short-circuit failure or open failure.

Further, in the charge control device of the battery pack, the abnormality is an open failure of either the first parallel switch or the second parallel switch, and the switch control unit is the first parallel switch and the second parallel switch. The first battery or the second battery, which can be charged by controlling either one of the second parallel switches to ON, may be charged.
In this case, even if either one of the first parallel switch and the second parallel switch fails to open, either the first parallel switch or the second parallel switch is controlled to be ON, so that the first battery or the second battery is used. The battery can be charged.

Further, in the charge control device of the battery pack, the abnormality is a short-circuit failure of either the first parallel switch or the second parallel switch, and the switch control unit is the first parallel switch and the second parallel switch. The first battery and the second battery may be charged by controlling either one of the second parallel switches to be turned on.
In this case, even if one of the first parallel switch and the second parallel switch fails due to a short circuit, the other of the first parallel switch and the second parallel switch is controlled to be ON, so that the first battery and the second battery are used. The batteries are connected in parallel and can charge the first battery and the second battery.

Further, in the charge control device of the battery pack, the abnormality is an opening failure of the series connection element, and the switch control unit controls the first parallel switch and the second parallel switch to be turned on. The first battery and the second battery may be charged.
In this case, even if the circuit element fails to open, the first parallel switch and the second parallel switch are turned on, so that the first battery and the second battery are connected in parallel, and the first battery and the second battery can be charged.

Further, in the charge control device of the battery pack, the series connection element may be configured to be a diode.
In this case, the load is not discharged while the first battery and the second battery are connected in series. Further, 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 of being discharged while being connected in series.

Further, in the present invention, a series connection element for connecting the first battery and the second battery in series and a series connection circuit for connecting the first battery and the series connection element in series with the second battery are connected in parallel. The first parallel switch to be used, the second parallel switch connected in series to the first battery and connected in parallel with the series connection circuit of the series connection element and the second battery, the first parallel switch and the first parallel switch. A switch control unit that controls two parallel switches is provided, and the switch control unit controls the first parallel switch and the second parallel switch to be off at the time of charging, and the first parallel switch and the first parallel switch at the time of discharging. A battery pack charge control method for controlling each of the second parallel switches to be turned on, and any one of the series connection element, the first parallel switch, and the second parallel switch, excluding a short-circuit failure of the series connection element. When an abnormality occurs in the switch control unit, the switch control unit is characterized in that at least one of the first parallel switch and the second parallel switch that can be turned on is controlled to be turned on and charged.

In the present invention, when an abnormality occurs in any 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 can be turned on is controlled by the switch control device. Will be done. Therefore, at least one of the first battery and the second battery is rechargeably connected and can be charged.

According to the present invention, a charge control device and a battery of a battery pack capable of charging 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 device of the battery pack which concerns on 1st Embodiment. It is a flow chart which shows the procedure of failure determination. (A) is a diagram showing a state of being charged in series during normal operation, and (b) is a diagram showing a state of discharging to a load during normal operation. (A) is a diagram showing a state at the time of charging in an open failure of the first parallel switch, and (b) is a diagram showing a state at the time of discharging to a load in an open failure of the first parallel switch. (A) is a diagram showing a state during charging due to a diode open failure, and (b) is a diagram showing a state during discharge to a load due to a diode open failure. (A) is a diagram showing a state at the time of charging in a short-circuit failure of the first parallel switch, and (b) is a diagram showing a state at the time of discharging to a load in a short-circuit failure of the first parallel switch. It is a figure which shows an example of the charge control device of the battery pack which concerns on 2nd Embodiment. (A) is a diagram showing a state at the time of charging in an open failure of a series switch, and (b) is a diagram showing a state at the time of discharging to a load in an open failure of a series switch.

(First Embodiment)
Hereinafter, the battery pack charge control device (hereinafter, referred to as “charge control device”) according to the 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.

The charge control device 10 shown in FIG. 1 is mounted on a vehicle such as an electric forklift and controls the charge 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. , Is equipped.

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 the connection point on the positive electrode side of the first battery 12 and the second battery 13, and the connection point B is the connection point on the negative electrode 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 electrode side of the first battery 12, and the cathode side of the diode 16 is connected to the positive electrode side of the second battery 13. Therefore, the diode 16 passes the current from the first battery 12 to the second battery 13 and cuts off the current from the second battery 13 to 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 the positive electrode side of the second battery 13 (between the contacts AD) in parallel with the first series connection circuit (circuit between the contacts ACD) in which the first battery 12 and the diode 16 are connected in series. : It is provided between the positive electrode of the first battery 12 and the connection point D). The second parallel switch 15 is connected to the negative electrode side (contact CB) of the first battery 12 in parallel with the second series connection circuit (circuit between the contact CDBs) in which the diode 16 and the second battery 13 are connected in series. Between: It is provided 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 series 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. As the first parallel switch 14 and the second parallel switch 15, a semiconductor relay may be used in addition to the mechanical relay.

On the negative electrode side (between the contacts AC) of the first battery 12, a first current detection unit 18 for detecting the current flowing through the first battery 12 is provided. A second current detection unit 19 for detecting the current flowing through the second battery 13 is provided on the negative electrode side (between the contact DBs) 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 the connection point A on the positive electrode side of the first battery 12 with the second battery 13 and the load 20, and is controlled on / off 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 alternating current and outputs the load, and a traveling motor driven by the electric power output from the inverter. The vehicle travels by driving the travel motor.

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

Further, 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 by the electric power supplied through 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 by using the 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 and the first battery 12 and the second battery 13 are electrically connected by the charging switch 23 while the power is being output from the charger 22, the charger 22 to the first battery 12 and the second battery 13 are connected. 2 Power is supplied to the battery 13. When the charger 22 and each of the first battery 12 and the second battery 13 are electrically disconnected by the charging switch 23, the 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 turned off during charging when there is no abnormality. By controlling the first parallel switch 14 and the second parallel switch 15 to be off, the first battery 12 and the second battery 13 are charged by the series connection. On the other hand, the battery ECU 17 controls the first parallel switch 14 and the second parallel switch 15 to be turned on at the time of discharging. When the first parallel switch 14 and the second parallel switch 15 are controlled to be ON, the first battery 12 and the second battery 13 are discharged by the parallel connection.

The battery ECU 17 outputs a current command value for charging to the charger 22. Further, the battery ECU 17 detects the charge rates 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 the detection signal of the current value detected by the first current detection unit 18 and the second current detection unit 19. The battery ECU 17 uses signals of the current values detected by the first current detection unit 18 and the second current detection unit 19 to cause an abnormality (open failure or short circuit failure) of the first parallel switch 14 and the second parallel switch 15. Detects an abnormality (open circuit failure) of the diode 16. An open failure is a failure in an open state in which energization cannot be performed, and a short-circuit failure is a failure in a short-circuit state in which energization cannot be cut off.

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

Explaining a series of steps (S01 to S14) of the failure determination program, first, the battery ECU 17 is in the process of discharging to the load 20 by connecting the first battery 12 and the second battery 13 in parallel (see step S01). 1 It is determined whether or not the current value of the current detection unit 18 or the second current detection unit 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 has an open failure (see step S03). ). After determining the open failure, the discharge is terminated (see step S04). Next, the battery ECU 17 charges 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 which are connected in series with the other of the open failures is not charged.

When it is determined in step S02 that the current value of the first current detection unit 18 or the second current detection unit 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. The charge is checked in this state (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 detection unit 18 and the second current detection unit 19 are both 0, the battery ECU 17 determines that the diode 16 has an open failure (see step S08). Next, the battery ECU 17 charges by turning on the first parallel switch 14 and the second parallel switch 15, respectively (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 at the same time.

When it is determined in step S07 that the current values of the first current detection unit 18 and the second current detection unit 19 are not 0, the battery ECU 17 determines that the current value of the first current detection unit 18 or the second current detection unit 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 has a short-circuit failure (see step S11). ). Next, the battery ECU 17 charges 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 at the same time.

Next, when it is determined in step S10 that the current value of the first current detection unit 18 or the second current detection unit 19 is not 0, the battery ECU 17 determines that there is no abnormality (see step S13). Next, the series connection is charged (step S14). At this time, the first battery 12 and the second battery 13 are charged in a series connection state. It should be noted that steps S06 to S14 are repeated not only during the check before charging by the series connection but also during the charging by the series connection.

Next, the 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 is charged. And the second battery 13 is discharged in a state of being connected in parallel. Specifically, as shown in FIG. 3A, the first parallel switch 14 and the second parallel switch 15 are controlled to be off, respectively, and the first battery 12 and the second battery 13 are connected in series during charging. It is charged in the state. As shown in FIG. 3B, at the time of discharging, the first parallel switch 14 and the second parallel switch 15 are controlled to be on, respectively, and the first battery 12 and the second battery 13 are discharged in a state of being connected in parallel. ..

Next, a charge control method for each abnormality of the first parallel switch 14 or the second parallel switch 15 (open failure or welding failure) and the diode 16 abnormality (open failure) 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 charge control device 10 can be turned on among the first parallel switch 14 and the second parallel switch 15. Turn on at least one of them to charge.

<Open failure of the first parallel switch 14 (or the second parallel switch 15)>
When the first parallel switch 14 fails to open, the current value detection signal of the second current detection unit 19 indicates a current value of 0 when discharging in parallel connection. Therefore, the battery ECU 17 determines that the first parallel switch 14 has an open failure. If the first parallel switch 14 fails to open, 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 determined by the battery ECU 17 to be fully charged, so that the first battery 12 is not charged. .. Therefore, in the present embodiment, as shown in FIG. 4A, when the first parallel switch 14 has an open failure, the battery ECU 17 controls the second parallel switch 15 that can be turned on at the time of charging to be turned on, and the first one. Charge the battery 12. By controlling the second parallel switch 15 to be turned on, the first battery 12 can be charged. The second battery 13 cannot be charged and discharged, and the battery capacity of the battery pack 11 is halved. However, as shown in FIG. 4B, the electric power charged in the first battery 12 is applied to the load 20. Discharge is possible.

Although not shown, when the second parallel switch 15 fails to open, the current value detection signal of the first current detection unit 18 indicates a current value of 0 when discharging in parallel connection. Therefore, charging and discharging of the first battery 12 becomes impossible. In this case, the battery ECU 17 controls the first parallel switch 14 to be turned on during charging to charge the second battery 13. By controlling the first parallel switch 14 to be turned 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 electric power charged in the second battery 13 enables discharge to the load 20.

In this way, when the first parallel switch 14 or the second parallel switch 15 fails to open, 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. Then, either 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, one of the first battery 12 and the second battery 13 connected in series with the other open failure is not charged.

<Open failure of diode 16>
In the case of open failure of the diode 16, even if the current value detection signals 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 18 and the second current detection unit 18 and the second current detection unit 18 are charged during series connection charging. 2 The current value detection signals of the current detection unit 19 each indicate a current value of 0. Therefore, the battery ECU 17 determines that the diode 16 has an open failure. 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 turned on, and the first battery 12 and the second battery connected in parallel. Charge 13 In the open failure of the diode 16, the first battery 12 and the second battery 13 cannot be charged by series connection, but the first parallel switch 14 and the second parallel switch 15 are controlled to be ON, so that the first battery 12 and the second battery 13 cannot be charged. The battery 12 and the second battery 13 are connected in parallel and can be charged. Further, as shown in FIG. 5B, the electric power charged in the first battery 12 and the second battery 13 enables discharge in parallel connection with respect to the load 20.

In this way, when the diode 16 fails to open, 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 failure 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 detection signal of the current value of the first current detection unit 18 does not show an appropriate current value at the time of checking before charging in series connection, so that the battery ECU 17 is the first. 1 It is determined that the parallel switch 14 has a short circuit failure. As shown in FIG. 6A, the battery ECU 17 controls the second parallel switch 15 to be turned on at the time of charging to charge the first battery 12 and the second battery 13 connected in parallel. In the case of a short-circuit failure of the first parallel switch 14, it is impossible to charge the first battery 12 and the second battery 13 by series connection, but the first battery 12 is controlled by turning on the second parallel switch 15. And the second battery 13 is connected in parallel and can be charged. Further, as shown in FIG. 6B, the electric power charged in the first battery 12 and the second battery 13 enables discharge in parallel connection with respect to the load 20.

Although not shown, when the second parallel switch 15 has a short-circuit failure (welding), the first parallel switch 14 is controlled to be turned on during charging. Although it is not possible to charge the first battery 12 and the second battery 13 by series connection, the first battery 12 and the second battery 13 are connected in parallel and charged by controlling the first parallel switch 14 to be turned on. Is possible. In this case as well, the electric power charged in the first battery 12 and the second battery 13 enables discharge in parallel connection with respect to the load 20.

In this way, when the first parallel switch 14 or the second parallel switch 15 fails in a short circuit, 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 and the second parallel switch 15 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.

If the first parallel switch 14 and the second parallel switch 15 fail to open, they can be charged in series, but can be discharged in parallel or either the first battery 12 or the second battery 13. Discharge is impossible. Further, when the first parallel switch 14 and the second parallel switch 15 are short-circuited and failed, charging by series connection becomes impossible, but the first parallel switch 14 and the second parallel switch 15 are not controlled in parallel. Charging and discharging by connection is possible.

According to this embodiment, the following effects are exhibited.
(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. Is controlled by. Therefore, at least one of the first battery 12 and the second battery 13 is rechargeably connected and can be charged.

(2) Even if either one of the first parallel switch 14 and the second parallel switch 15 fails to open, one of the first parallel switch 14 and the second parallel switch 15 is controlled to be ON, so that the first The battery 12 or the second battery 13 can be charged.

(3) Even if either one of the first parallel switch 14 and the second parallel switch 15 fails due to a short circuit, either the first parallel switch 14 or the second parallel switch 15 is controlled to be ON, so that the first The battery 12 and the second battery 13 can be connected in parallel and charged.

(4) Even if the diode 16 fails to open, the first parallel switch 14 and the second parallel switch 15 are controlled to be ON, so that the first battery 12 and the second battery 13 can be connected in parallel and charged. ..

(5) A diode 16 is used as a series connection element for connecting the first battery 12 and the second battery 13 in series, but the diode 16 is in a direction in which the electric power of the first battery 12 and the second battery 13 connected in series is discharged. It is provided so as to block the current to the battery. Therefore, the high-voltage power of the first battery 12 and the second battery 13 connected in series is not discharged to the load 20. Further, even if some external short circuit occurs in the connector of the battery pack 11, the electric power of the first battery 12 and the second battery 13 connected in series is not discharged to the load 20.

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

As shown in FIG. 7, in the charge control device 30, the 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 to be turned on and off by the battery ECU 17, and a semiconductor relay may be used in addition to the mechanical relay. When the first battery 12 and the second battery 13 are charged 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.

If the series switch 31 fails to open, charging of the first battery 12 and the second battery 13 by series connection becomes impossible. When the series switch 31 is opened, the first current detector 18 and the first current detector 18 and the second parallel switch 15 are controlled to be off when the first parallel switch 14 and the second parallel switch 15 are turned off and the first battery 12 and the second battery 13 connected in series are charged. The determination is made when the current value of the second current detection unit 19 becomes 0. As shown in FIG. 8A, when the series switch 31 fails to open, 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, the electric power charged in the first battery 12 and the second battery 13 enables discharge in parallel connection with respect to the load 20.

The present embodiment exhibits the same effects as those of the first embodiment (1) to (4). 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 can be made within the scope of the gist of the invention. For example, the present invention may be modified as follows.

○ In the above embodiment, the battery pack is mounted on a vehicle such as an electric forklift, and the charge control device controls the charging and discharging of the battery pack. However, the battery pack is a battery pack mounted on the vehicle. Not limited. Further, although the first battery and the second battery are assembled batteries in which a plurality of battery cells are connected in series, a configuration having a single battery cell may be used. Further, the battery cell is not limited to the lithium ion secondary battery, and may be a nickel hydrogen secondary battery or a lead storage battery.
○ In the above embodiment, the charger is provided with a charging switch, but the charging switch may be provided in the battery pack.

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

Claims (6)

A series connection element that connects the first battery and the second battery in series,
A first parallel switch that is connected in series to the second battery and is connected in parallel with the series connection circuit of the first battery and the series connection element.
A second parallel switch that is connected in series to the first battery and is connected in parallel with the 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 is provided.
The switch control unit
At the time of charging, the first parallel switch and the second parallel switch are controlled to be off, respectively.
A battery pack charge control device that controls 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 the short circuit failure of the series connection element.
The switch control unit
A battery pack charge control device for charging by controlling at least one of the first parallel switch and the second parallel switch that can be turned on. The abnormality is an open failure of either the first parallel switch or the second parallel switch.
Claim 1 is characterized in that the switch control unit charges the first battery or the second battery that can be charged by controlling the on or the other of the first parallel switch and the second parallel switch. The battery pack charge control device described. The abnormality is a short-circuit failure of either the first parallel switch or the second parallel switch.
The battery according to claim 1, wherein the switch control unit controls either one of the first parallel switch and the second parallel switch to be turned on to charge the first battery and the second battery. Charge control device for the pack. The abnormality is an open failure of the series connection element.
The charge control of the battery pack according to claim 1, wherein the switch control unit controls the first parallel switch and the second parallel switch to be turned on to charge the first battery and the second battery. apparatus. The battery pack charge control device according to any one of claims 1 to 4, wherein the series connection element is a diode. A series connection element that connects the first battery and the second battery in series,
A first parallel switch that is connected in series to the second battery and is connected in parallel with the series connection circuit of the first battery and the series connection element.
A second parallel switch that is connected in series to the first battery and is connected in parallel with the 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 is provided.
The switch control unit
At the time of charging, the first parallel switch and the second parallel switch are controlled to be off, respectively.
It is a charge control method of a battery pack that controls 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 the short circuit failure of the series connection element.
The switch control unit
A method for controlling charging of a battery pack, which comprises controlling and charging at least one of the first parallel switch and the second parallel switch that can be turned on.

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