How to connect the batteries in a combined battery pack

Abstract

To provide a battery connection method for a long-life combined battery pack in which measures against sparks when a switch is opened and closed are taken into consideration, and which has simple processing contents and can connect the batteries to each other in a short time. [Solution] After completing advance preparations, as a voltage raising and lowering operation, the control device 16 charges the combined battery pack 10 until the voltage value becomes the product of the number of series-connected cells constituting each EV battery 12 and 4.00 to 4.10 V, and then the control device 16 repeatedly discharges the combined battery pack 10 until the voltage value becomes the product of the number of series-connected cells constituting each EV battery 12 and 2.90 to 3.05 V. Furthermore, during this voltage raising and lowering operation, the voltage difference ΔV between the voltage Va of one EV battery among the EV batteries 12 and the voltage Vb of the lead-acid battery series group 14 satisfies the formula (1): 0≦|ΔV|

Description

[Technical field]

[0001] The present invention relates to a battery connection method for a combined battery pack composed of a plurality of lead-acid batteries and a plurality of lithium-ion batteries connected in parallel with each other. [Background technology]

[0002] It is known that a combined battery in which a lead-acid battery and a lithium-ion battery are connected in parallel can increase the stored energy per unit weight and can improve the low-temperature power performance in particular. In order to improve the safety of the combined battery, various techniques have been disclosed.

[0003] Meanwhile, regarding safety when the secondary batteries constituting the power storage device deteriorate, Patent Document 1 discloses a charge / discharge control device that measures the current value of each cell during charging and controls a switching element to disconnect an abnormal cell detected based on the measured value from the parallel connection. Patent Document 2 describes a battery system for railway vehicles that includes one or more battery boxes containing multiple parallel-connected battery groups and that minimizes the number of contactors required to suppress cross current between the battery groups or battery boxes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2013-038884 [Patent Document 2] Patent Publication No. 2023-175463 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 has a problem in that it does not take into consideration measures against sparks when the switch is opened and closed. Patent Document 2 has a problem in that the closed circuit voltage when a cross current occurs must be calculated using the open circuit voltage of the cell to determine whether the contactor can be closed or not, and the criteria for determining whether the contactor can be closed must be changed depending on whether the cross current is a charging current or a discharging current, making the processing complicated. In addition, it does not take into consideration not only charging but also discharging when charging is possible, so there is a problem in that it is not possible to align the voltages of the storage battery group or battery box and connect them to each other in a short time while charging is possible.

[0006] The present invention has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present invention is to provide a battery connection method for a long-life combined battery pack that takes into consideration measures against sparks when the switch is opened and closed. In addition to the above object, another object of the present invention is to provide a method for connecting batteries in a combined battery pack, which involves simple processing and enables interconnection in a short time. [Means for solving the problem]

[0007] In order to achieve the above object, the inventors conducted extensive research and discovered that, first, by preventing an overcurrent from flowing when the switch is turned on, it is possible to prevent sparks from occurring or, if sparks do occur, to minimize damage to the switch.

[0008] The inventors also discovered that by charging and discharging the combined battery pack and bringing the voltage on the combined battery pack side closer to the voltage of the unconnected batteries, it is possible to prevent an overcurrent from flowing when the battery is switched on, and thus arrived at the present invention.

[0009] That is, in order to configure a combined battery pack 10 as advance preparation, the present invention arranges a plurality of EV batteries inside a housing, connects each EV battery in parallel to configure a parallel group, connects a series group of lead-acid batteries, each of which is configured by connecting a pre-calculated number of lead-acid batteries in series to each parallel group of EV batteries, connects a data line measuring the voltage Va of each EV battery between the control device and each EV battery, connects a data line measuring the voltage Vb of the series group of lead-acid batteries between the control device and the series group of lead-acid batteries, and the control device acquires the internal impedance R and maximum allowable current Imax of each EV battery in advance, and confirms that the contactor switches connected in series to each EV battery are open, and performs advance preparation. After completion of the voltage increase / decrease operation, the control device charges the combined battery pack until the voltage value becomes the product of the number of cells connected in series that make up each EV battery and 4.00 to 4.10 V, and then discharges the combined battery pack until the voltage value becomes the product of the number of cells connected in series that make up each EV battery and 2.90 to 3.05 V. During the voltage increase / decrease operation, when the voltage difference ΔV between the voltage Va of one EV battery among the EV batteries and the voltage Vb of the series group of lead-acid batteries satisfies the following formula (1), the control device performs a battery connection operation to close a contactor switch connected in series to one EV battery, and repeats the battery connection operation for another EV battery among the EV batteries. 0≦|ΔV| <Imax×R···(1)

[0010] Here, in the above, the series group of lead-acid batteries refers to a group of multiple series groups of lead-acid batteries connected in parallel with each other, and if the voltage difference between the series groups of lead-acid batteries increases while the control device repeatedly charges and discharges the combined battery pack, it is preferable for the control device to fully charge the combined battery pack and then leave it for 10 to 30 hours to equalize the voltages of the series groups of lead-acid batteries. Effect of the Invention

[0011] According to the present invention, measures against sparks occurring when the switch is opened and closed are taken into consideration, so that the switch can have a long life. Furthermore, according to the present invention, in addition to the above effects, the processing contents are simple and interconnection can be achieved in a short time. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a combined battery pack suitable for carrying out the battery connection method for a combined battery pack of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The battery connection method for a combined battery pack of the present invention will be described in detail below with reference to the preferred embodiments shown in the accompanying drawings. Fig. 1 is a block diagram showing a combined battery pack suitable for carrying out the battery connection method for a combined battery pack of the present invention.

[0014] In the battery connection method of the combined battery pack of the present invention, in order to configure the combined battery pack 10 as a preliminary step, first, multiple EV batteries 12 are placed inside a housing (not shown), and each EV battery 12 is connected in parallel to configure a parallel group. Next, a lead-acid battery series group 14, which is configured by connecting a pre-calculated number of lead-acid batteries in series to each other, is connected in parallel to each parallel group of EV batteries 12. At the same time, a data line 18a for measuring the voltage Va of each EV battery 12 is connected between the control device 16 and each EV battery 12, and a data line 18b for measuring the voltage Vb of the lead-acid battery series group 14 is connected between the control device 16 and the lead-acid battery series group 14. Next, the control device 16 acquires the internal impedance R and maximum allowable current Imax of each EV battery 12 in advance, and confirms that the contactor switch 20 connected in series to each EV battery 12 is open.

[0015] After the advance preparation is completed, as a voltage raising and lowering operation, the control device 16 charges the combined battery pack 10 until the voltage value becomes the product of the number of series-connected cells constituting each EV battery 12 and 4.00 to 4.10 V, and then the control device 16 discharges the combined battery pack 10 until the voltage value becomes the product of the number of series-connected cells constituting each EV battery 12 and 2.90 to 3.05 V. Furthermore, during the voltage raising and lowering operation, when the voltage difference ΔV between the voltage Va of one EV battery among the EV batteries 12 and the voltage Vb of the lead-acid battery series group 14 satisfies the following formula (1), the control device 16 performs a battery connection operation to close the contactor switch 20 connected in series to one EV battery. Then, the battery connection operation is repeated for the other EV battery among the EV batteries 12. 0≦|ΔV| <Imax×R···(1)

[0016] When the lead-acid battery series group 14 is a group of multiple lead-acid batteries connected in parallel with each other, if the voltage difference between the lead-acid battery series groups increases while the control device 16 repeatedly charges and discharges the combined battery pack 10, it is preferable for the control device 16 to fully charge the combined battery pack 10 and then leave it for 10 to 30 hours to equalize the voltages of the lead-acid battery series groups.

[0017] Here, the EV battery is a secondary battery installed in so-called electric vehicles and hybrid vehicles, and a representative example is a lithium-ion battery. A spark is a spark phenomenon that occurs between the positive and negative contacts of the contactor switch 20 due to discharge, and if a spark occurs, the contacts and the resin members around them may deteriorate or be damaged. In the above explanation, A to BV means a voltage range of A volts or more and less than B volts.

[0018] Each EV battery 12 may be housed in an individual container as a battery pack 22. There is no limitation on the means for measuring the voltage Va of each EV battery 12, but it may be measured by a battery management system 24 provided in an individual container that houses each EV battery 12. There is no limitation on the means for measuring the voltage Vb of the lead-acid battery series group 14, but it may be measured by the control device 16.

[0019] With this configuration, the battery connection method for the combined battery pack of the present invention takes into consideration measures against sparks that may occur when the switch is opened and closed, thereby enabling the battery pack to have a long life. Furthermore, in addition to the above-mentioned effects, the battery connection method for a combined battery pack of the present invention has simple processing steps and allows interconnection in a short time. The battery connection method for a combined battery pack of the present invention is basically configured as described above.

[0020] Although the battery connection method of the combined battery pack of the present invention has been described in detail above, the present invention is not limited to the above description, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Industrial Applicability]

[0021] The battery connection method for a combined battery pack of the present invention takes into consideration measures against sparks when the switch is opened and closed, thereby having the effect of enabling a long battery life. In addition, the processing is simple and the interconnections can be made in a short time, making it industrially useful. [Explanation of symbols]

[0022] 10 Combined Battery Pack 12 EV battery 14 Lead-acid batteries in series 16 Control device 18a, 18b data lines 20 Contactor Switch 22 Battery Pack 24 Battery Management System

Claims

1. In order to prepare the combined battery pack 10 in advance, a plurality of EV batteries are arranged inside a housing, and the EV batteries are connected in parallel to each other to form a parallel group. a series group of lead-acid batteries, each of which is configured by connecting a pre-calculated number of lead-acid batteries in series with each other, is connected in parallel to the parallel group of each EV battery, a data line for measuring a voltage Va of each EV battery is connected between a control device and each EV battery, and a data line for measuring a voltage Vb of the series group of lead-acid batteries is connected between the control device and the series group of lead-acid batteries; The control device acquires the internal impedance R and the maximum allowable current Imax of each EV battery in advance, and confirms that the contactor switch connected in series to each EV battery is open; After the advance preparation is completed, as a voltage raising and lowering operation, the control device charges the combined battery pack until a voltage value is a product of the number of cells connected in series constituting each EV battery and 4.00 to 4.10 V, and then the control device discharges the combined battery pack until a voltage value is a product of the number of cells connected in series constituting each EV battery and 2.90 to 3.05 V; During the voltage raising and lowering operation, when a voltage difference ΔV between a voltage Va of one of the EV batteries and a voltage Vb of the series group of lead-acid batteries satisfies the following formula (1), the control device performs a battery connection operation to close a contactor switch connected in series to the one EV battery, The battery connection method for a combined battery pack includes repeating the battery connection operation for another one of the EV batteries. 0≦|ΔV|<Imax×R...(1)

2. the lead-acid battery series group is a group of a plurality of lead-acid batteries connected in parallel with each other, 2. The battery connection method for a combined battery pack according to claim 1, wherein, when a voltage difference between the series groups of lead-acid batteries increases while the control device repeatedly charges and discharges the combined battery pack, the control device fully charges the combined battery pack and then leaves it for 10 to 30 hours to equalize the voltages of the series groups of lead-acid batteries.

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