Vehicle battery device

Abstract

It comprises: a plurality of battery cell groups in which the battery cells are connected in series; a connection switch capable of switching the electrical connection between the plurality of battery cell groups to a series connection or a parallel connection; and a current sensor for detecting the current flowing through each battery cell group in both the series connection and the parallel connection, the current sensor being arranged near the positive terminal or the negative terminal of each of the battery cell groups.

Description

Technical Field

[0001] The present invention relates to a battery device for a vehicle.

[0002] This application claims priority based on Tokugan Application No. 2018-062443 filed in Japan on March 28, 2018, the contents of which are incorporated herein by reference. Background Art

[0003] Patent Document 1 listed below discloses a power conversion device including a plurality of battery cell groups and switching the electrical connection between the plurality of battery cell groups between series connection and parallel connection.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: (Japanese) Patent Publication No. 2008-67500 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in order to calculate the state of charge (SOC) of each battery cell group or to perform maintenance and inspection, etc., it is desirable to detect the current flowing through each battery cell group in both the series connection and the parallel connection. However, Patent Document 1 discloses connecting a plurality of battery cell groups in a series state or a parallel state, but does not suggest or disclose how to detect the current of each battery cell group in both the series connection and the parallel connection.

[0009] In one embodiment of the present invention, an object is to detect current flowing through each battery cell group regardless of whether the connection between a plurality of battery cell groups is a series connection or a parallel connection.

[0010] Means for solving problems

[0011] (1) One embodiment of the present invention is a vehicle battery device, characterized in that it comprises: a plurality of battery cell groups in which battery cells are connected in series; a connection switch capable of switching the electrical connection between the plurality of battery cell groups to a series connection or a parallel connection; and a current sensor for detecting the current flowing through each battery cell group in both the series connection and the parallel connection, the current sensor being disposed near the positive terminal or the negative terminal of each of the battery cell groups.

[0012] (2) In the vehicle battery device of (1) above, the current sensor may be connected to a current path between a positive terminal or a negative terminal of each of the battery cell groups and the connection switch.

[0013] (3) In the vehicle battery device of (2) above, the current sensor may be connected between the positive electrode terminal or the negative electrode terminal and a branch point where the current path branches.

[0014] (4) In one of the vehicle storage battery devices of (1) to (3) above, it is also possible to further include: a charging control unit that controls the connection switch to an on state or an off state so as to connect the plurality of battery cell groups in series and charge each of the battery cell groups using power supplied from the outside. Furthermore, the charging control unit detects the current flowing through each of the battery cell groups connected in series based on the current detected by each of the current sensors when the plurality of battery cell groups are connected in series.

[0015] (5) In the vehicle battery device of (4) above, the charging control unit may further include: a fault determination unit that determines whether each current sensor has a fault by comparing the currents detected by each current sensor when the plurality of battery cell groups are connected in series.

[0016] Effects of the Invention

[0017] In one embodiment of the present invention, the current flowing through each battery cell group can be detected regardless of whether the connection between the plurality of battery cell groups is a series connection or a parallel connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing an example of a schematic configuration of a vehicle 2 equipped with a vehicle battery device 3 charged by an external charger 1 according to an embodiment of the present invention.

[0019] Figure 2 This is a flowchart of a failure determination process according to one embodiment of the present invention.

[0020] Figure 3 This is a diagram showing a state where a plurality of battery cell groups 10 - 1 to 10 - 3 are connected in series according to one embodiment of the present invention.

[0021] Figure 4 This is a flowchart of a modified example of the failure determination process according to one embodiment of the present invention.

[0022] Description of symbols

[0023] 1 External charger

[0024] 2 Vehicles

[0025] 3. Vehicle battery device

[0026] 10 battery cell group

[0027] 14 Parallel connection switches

[0028] 15 Series connection switches

[0029] 16 Current sensor

[0030] 19 Charging control unit

[0031] 191 Switching Control Unit

[0032] 192 Current detection unit

[0033] 193 Fault determination unit DETAILED DESCRIPTION

[0034] Hereinafter, a vehicle battery device according to an embodiment of the present invention will be described with reference to the drawings.

[0035] Figure 1 This is a diagram showing an example of a schematic configuration of a vehicle 2 equipped with a vehicle battery device 3 charged by an external charger 1 according to an embodiment of the present invention.

[0036] The external charger 1 is a device or equipment that charges the assembled battery (battery) in the vehicle battery device 3 from outside the vehicle (external charging). The external charger 1 is, for example, a charging station or a portable power source. For example, the charging station is installed in a commercial facility or a parking lot.

[0037] The vehicle 2 is, for example, a hybrid vehicle or an electric vehicle and includes a vehicle battery device 3 , a first contactor 11 , a precharge circuit 11 a , a second contactor 12 , an inverter 13 , and a connector 40 .

[0038] The vehicle battery device 3 includes a plurality of battery cell groups 10 (10-1 to 10-3), a plurality of parallel connection switches 14 (14-1 to 14-6), a plurality of series connection switches 15 (15-1, 15-2), a plurality of current sensors 16 (16-1 to 16-3), an AC / DC converter 18, and a charging control unit 19. The assembled battery mounted on the vehicle 2 includes a plurality of battery cell groups 10. The parallel connection switch 14 and the series connection switch 15 are examples of the "connection switch" of the present invention.

[0039] In each battery cell group 10, n battery cells b1 to bn are connected in series. In each battery cell group 10, the positive terminal of the battery cell b1 (the uppermost cell) located at the top is the positive terminal (one output terminal) T1 of the battery cell group 10. In each battery cell group 10, the negative terminal of the battery cell bn (the lowermost cell) located at the bottom is the negative terminal (another output terminal) T2 of the battery cell group 10. The above-mentioned "n" is a natural number greater than 2. The case in which the vehicle battery device 3 of the present embodiment has three battery cell groups 10 is described, but the present invention is not limited to this, and if there are multiple battery cell groups, their number is not particularly limited.

[0040] As for the first contactor 11, the first contact is connected to the positive terminal of the battery pack, and the second contact is connected to the first input terminal of the inverter 13. The first contactor 11 changes to an open state for electrically connecting the first contact and the second contact or a closed state for releasing the electrical connection between the first contact and the second contact according to the control from the charging control unit 19. For example, the first contactor 11 is an energized switch.

[0041] The precharge circuit 11 a is connected in parallel with the first contactor 11 .

[0042] As for the second contactor 12, the first contact is connected to the negative terminal of the battery pack, and the second contact is connected to the second input terminal of the inverter 13. The second contactor 12 changes to an open state for electrically connecting the first contact and the second contact or a closed state for releasing the electrical connection between the first contact and the second contact according to the control from the charging control unit 19. For example, the second contactor 12 is an energized switch.

[0043] The inverter 13 includes a first input terminal and a second input terminal. The inverter 13 converts the DC power of the assembled battery input to the first input terminal and the second input terminal into AC power, and outputs the converted AC power to a load (eg, a driving motor) in the vehicle.

[0044] The parallel connection switch 14 is connected between the first contact of the first contactor 11 and the first contact of the second contactor 12. The parallel connection switch 14 is a switch capable of connecting a plurality of battery cell groups 10 in parallel (parallel connection).

[0045] Specifically, the first terminal of the parallel connection switch 14-1 is connected to the first contact of the first contactor 11, and the second terminal is connected to the positive terminal T1 of the battery cell group 10-1. The first terminal of the parallel connection switch 14-2 is connected to the first contact of the first contactor 11, and the second terminal is connected to the positive terminal T1 of the battery cell group 10-2. The first terminal of the parallel connection switch 14-3 is connected to the first contact of the first contactor 11, and the second terminal is connected to the positive terminal T1 of the battery cell group 10-3.

[0046] The parallel connection switch 14-4 has a first terminal connected to the negative terminal T2 of the battery cell group 10-1, and a second terminal connected to the first contact of the second contactor 12. The parallel connection switch 14-5 has a first terminal connected to the negative terminal T2 of the battery cell group 10-2, and a second terminal connected to the first contact of the second contactor 12. The parallel connection switch 14-6 has a first terminal connected to the negative terminal T2 of the battery cell group 10-3, and a second terminal connected to the first contact of the second contactor 12.

[0047] The series connection switch 15 is connected between the first contact of the first contactor 11 and the first contact of the second contactor 12. The series connection switch 15 is a switch capable of connecting a plurality of battery cell groups 10 in series (series connection).

[0048] Specifically, the first terminal of the series connection switch 15-1 is connected to the negative terminal T2 of the battery cell group 10-1, and the second terminal is connected to the positive terminal T1 of the battery cell group 10-2. The first terminal of the series connection switch 15-2 is connected to the negative terminal T2 of the battery cell group 10-2, and the second terminal is connected to the positive terminal T1 of the battery cell group 10-3.

[0049] The current sensor 16 (16-1 to 16-3) is provided in each battery cell group 10-1 to 10-3. Regardless of whether the battery cell groups 10-1 to 10-3 are electrically connected in series or in parallel, the current sensor 16 (16-1 to 16-3) detects the current value flowing through each battery cell group 10-1 to 10-3. For example, the current sensor 16 may also be a shunt resistor. In addition, the current sensor 16 may also include a Hall element or a current transformer.

[0050] Each of the current sensors 16 - 1 to 16 - 3 is provided in the vicinity of the positive electrode terminal T1 or the negative electrode terminal T2 of the corresponding battery cell group 10 - 1 to 10 - 3 .

[0051] The current sensor 16 - 1 detects the current value I1 flowing through the battery cell group 10 - 1 . The current sensor 16 - 1 is connected between the negative terminal T2 of the battery cell group 10 - 1 and the first terminal of the series connection switch 15 - 1 . The current sensor 16 - 1 outputs the detected current value I1 to the charging control unit 19 .

[0052] For example, the current sensor 16-1 is connected between the negative terminal T2 of the battery cell group 10-1 and the connection point N1 of the first terminal of the parallel connection switch 14-4 and the first terminal of the series connection switch 15-1. The current sensor 16-1 may also be connected between the positive terminal T1 of the battery cell group 10-1 and the second terminal of the parallel connection switch 14-1.

[0053] Here, for example, the positive terminal T1 of each battery cell group 10 and the parallel connection switches 14-1 to 14-3 are electrically connected through a wiring member such as a bus bar or a cable. For example, the negative terminal T2 of each battery cell group 10 and the parallel connection switches 14-4 to 14-6 are electrically connected through a wiring member such as a bus bar or a cable. For example, the negative terminal T2 of the battery cell group 10-1 and the series connection switch 15-1 are electrically connected through a wiring member such as a bus bar or a cable. For example, the positive terminal T1 of the battery cell group 10-2 and the series connection switch 15-1 are electrically connected through a wiring member such as a bus bar or a cable. For example, the negative terminal T2 of the battery cell group 10-2 and the series connection switch 15-2 are electrically connected through a wiring member such as a bus bar or a cable. For example, the positive terminal T1 of the battery cell group 10-3 and the series connection switch 15-2 are electrically connected through a wiring member such as a bus bar or a cable. Thus, in the case where the current sensor 16-1 is disposed near the positive terminal T1 of the battery cell group 10-1, the current sensor 16-1 may also be disposed in a wiring member between the positive terminal T1 of the battery cell group 10-1 and the second terminal of the parallel connection switch 14-1. Among them, there is a case where the wiring member and components such as switches different from the parallel connection switch 14-1 (not shown) are wired so that the current path branches into multiple ones. In this case, the current sensor 16-1 may also be connected to the current path between the branch point of the wiring from the positive terminal T1 of the battery cell group 10-1 to the second terminal of the parallel connection switch 14-1 and the positive terminal T1 of the battery cell group 10-1. For example, the current sensor 16-1 may also be connected in a wiring member that electrically connects the positive terminal T1 of the battery cell group 10-1 and the second terminal of the parallel connection switch 14-1, between the branch point of the wiring member and the positive terminal T1 of the battery cell group 10-1. In the case where there are multiple branch points, the current sensor 16-1 can also be connected among the multiple branch points of the wiring component that electrically connects the positive terminal T1 of the battery cell group 10-1 and the second terminal of the parallel connection switch 14-1, between the branch point closest to the positive terminal T1 of the battery cell group 10-1 and the positive terminal T1 of the battery cell group 10-1.

[0054] The current sensor 16-1 is provided between the above-mentioned branch point and the battery cell group 10-1, and the negative terminal T2 of the battery cell group 10-1 can also be applied in the same manner. There is a case where the current sensor 16-1 of the present embodiment is provided near the negative terminal T2 of the battery cell group 10-1. In this case, the current sensor 16-1 is connected to the current path between the branch point (for example, the connection point N1) of the wiring from the negative terminal T2 of the battery cell group 10-1 to the first terminal of the series connection switch 15-1 and the negative terminal T2 of the battery cell group 10-1.

[0055] The current sensor 16 - 2 detects the current value I2 flowing through the battery cell group 10 - 2 . The current sensor 16 - 2 is connected between the negative terminal T2 of the battery cell group 10 - 2 and the first terminal of the series connection switch 15 - 2 . The current sensor 16 - 2 outputs the detected current value I2 to the charging control unit 19 .

[0056] For example, the current sensor 16-2 is connected between the negative terminal T2 of the battery cell group 10-2 and the connection point N3 of the first terminal of the parallel connection switch 14-5 and the first terminal of the series connection switch 15-2. However, the current sensor 16-2 may also be connected between the positive terminal T1 of the battery cell group 10-2 and the second terminal of the series connection switch 15-1.

[0057] For example, when the current sensor 16-2 is provided near the positive terminal T1 of the battery cell group 10-2, the current sensor 16-2 is connected to the current path between the branch point of the wiring from the positive terminal T1 of the battery cell group 10-2 to the second terminal of the series connection switch 15-1 and the positive terminal T1 of the battery cell group 10-2. The branch point is, for example, the connection point N2 between the positive terminal T1 of the battery cell group 10-2 and the second terminal of the series connection switch 15-1.

[0058] In the case where the current sensor 16-2 of the present embodiment is disposed near the negative terminal T2 of the battery cell group 10-2, the current sensor 16-2 may also be connected to a current path between a branch point (for example, connection point N3) of the wiring from the negative terminal T2 of the battery cell group 10-2 to the first terminal of the series-connected switch 15-2 and the negative terminal T2 of the battery cell group 10-2.

[0059] The current sensor 16-3 detects the current value I3 flowing through the battery cell group 10-3. The current sensor 16-3 is connected between the negative terminal T2 of the battery cell group 10-3 and the first terminal of the parallel connection switch 14-6. The current sensor 16-3 may also be connected between the positive terminal T1 of the battery cell group 10-3 and the second terminal of the series connection switch 15-2. The current sensor 16-3 outputs the detected current value I3 to the charging control unit 19.

[0060] For example, when the current sensor 16-3 is provided near the positive terminal T1 of the battery cell group 10-3, the current sensor 16-3 may be connected to the current path between the branch point of the wiring from the positive terminal T1 of the battery cell group 10-3 to the second terminal of the series connection switch 15-2 and the positive terminal T1 of the battery cell group 10-3. The branch point is, for example, the connection point N4 between the positive terminal T1 of the battery cell group 10-3 and the second terminal of the series connection switch 15-2.

[0061] The connector 40 connects the vehicle battery device 3 to the external charger 1 . The connector 40 is coupled to the charging plug 17 of the external charger 1 to connect the external charger 1 and the vehicle battery device 3 .

[0062] AC / DC converter 18 converts AC power supplied from external charger 1 via charging plug 17 into DC power. AC / DC converter 18 supplies the converted DC power to first terminals of parallel connection switches 14-1 to 14-3.

[0063] The charging control unit 19 controls external charging of the battery cell groups 10 - 1 to 10 - 3 from the external charger 1. The charging control unit 19 according to the present embodiment will be described below.

[0064] The charging control unit 19 includes a switching control unit 191 , a current detection unit 192 , and a failure determination unit 193 .

[0065] The switching control unit 191 controls each of the parallel connection switches 14 - 1 to 14 - 6 and the series connection switches 15 - 1 and 15 - 2 to an on state or an off state, thereby connecting the plurality of battery cell groups 10 - 1 to 10 - 3 in parallel or in series.

[0066] For example, the switching control unit 191 controls the parallel connection switches 14-1, 14-6 and the series connection switches 15-1, 15-2 to be in the on state, and controls the parallel connection switches 14-2 to 14-5 to be in the off state, thereby connecting the plurality of battery cell groups 10-1 to 10-3 in series. The switching control unit 191 controls the parallel connection switches 14-1 to 14-6 to be in the on state, and controls the series connection switches 15-1, 15-2 to be in the off state, thereby connecting the plurality of battery cell groups 10-1 to 10-3 in parallel. The switching control unit 191 connects the plurality of battery cell groups 10-1 to 10-3 in series when the battery cell groups 10-1 to 10-3 are externally charged.

[0067] When a plurality of battery cell groups 10-1 to 10-3 are connected in series, the current detection unit 192 detects the current value Is flowing through each battery cell group 10-1 to 10-3 connected in series based on the current values ​​I1 to I3 detected by each current sensor 16-1 to 16-3. As a result, the deviation of the detection value of each current sensor 16-1 to 16-3 is reduced, and the relative accuracy of the current value Is is improved. In this case, since the battery cell groups 10-1 to 10-3 are connected in series, the current value of the current Is flowing through each battery cell group 10-1 to 10-3 becomes the same. The charging control unit 19 may also calculate the SOC (State Of Charge) of each battery cell group 10-1 to 10-3 based on the current Is.

[0068] As a detection method of the current Is detected by the current detection unit 192, for example, when a plurality of battery cell groups 10-1 to 10-3 are connected in series, the current detection unit 192 calculates the average value of the current values ​​I1 to I3 detected by each current sensor 16-1 to 16-3, and detects the calculated average value as the current value Is. The detection method of the current Is of this embodiment is any method that can improve the relative accuracy of the current value Is, and is not limited to averaging. For example, the current detection unit 192 may detect the median value of the current values ​​I1 to I3 as the current value Is.

[0069] The fault determination unit 193 compares the current values ​​I1 to I3 detected by the current sensors 16-1 to 16-3 with each other when the plurality of battery cell groups 10-1 to 10-3 are connected in series, thereby performing a fault determination process to determine whether each current sensor 16-1 to 16-3 has a fault. For example, the fault determination unit 193 compares the current values ​​I1 to I3 with each other using the principle of majority decision, and determines that the current sensor 16 that detects the minority current value as a result of the comparison is faulty. For example, when one of the current values ​​I1 to I3 is different from the other multiple current values, the fault determination unit 193 determines that a fault has occurred in the current sensor 16 that detected the one current value.

[0070] Next, use Figure 2 , 3 The failure determination process according to the present embodiment will be described. In the following description, a case where the failure determination unit 193 executes the failure determination process during external charging will be described.

[0071] When the plurality of battery cell groups 10-1 to 10-3 are externally charged, the user connects the charging plug 17 of the external charger 1 to the connector 40 of the vehicle 2. As a result, the charging control unit 19 can communicate with the external charger 1 through CAN (Controller Area Network) communication or the like. Thus, the charging control unit 19 communicates with the external charger 1 to detect the connection of the charging plug 17 to the vehicle 2, that is, the external connection. As a result, the charging control unit 19 authenticates the external connection (step S101).

[0072] When the charging control unit 19 detects external connection, it controls the parallel connection switches 14-1, 14-6 and the series connection switches 15-1, 15-2 to be turned on, and controls the parallel connection switches 14-2 to 14-5 to be turned off, thereby connecting the plurality of battery cell groups 10-1 to 10-3 in series (step S102). When the plurality of battery cell groups 10-1 to 10-3 are connected in series, the charging control unit 19 starts external charging (step S103).

[0073] When external charging is started, the power supplied from the external charger 1 to the vehicle 2 is converted into direct current by the AC / DC converter 18 and supplied to the plurality of battery cell groups 10-1 to 10-3. Figure 3 As shown, if external charging is started, the charging current flows through the current path W in the order of parallel connection switch 14-1, battery cell group 10-1, connection point N1, series connection switch 15-1, connection point N2, battery cell group 10-2, connection point N3, series connection switch 15-2, connection point N4, battery cell group 10-3, and parallel connection switch 14-6.

[0074] Here, since the current sensors 16 - 1 to 16 - 3 are provided in the current path W, the current sensors 16 - 1 to 16 - 3 detect current values ​​I1 to I3 during external charging (step S104 ). Then, the current sensors 16 - 1 to 16 - 3 output the detected current values ​​I1 to I3 to the charging control unit 19 .

[0075] When the failure determination unit 193 obtains the current values ​​I1 to I3 from the current sensors 16 - 1 to 16 - 3 during external charging, it determines whether or not the current sensors 16 - 1 to 16 - 3 have a failure based on the current values ​​I1 to I3 .

[0076] Here, if each current sensor 16-1 to 16-3 has no fault, each current value I1 to I3 is the same value as each other, and the current value Is (in this embodiment, the current value of the charging current) is shown. However, when one of the current sensors 16-1 to 16-3 fails, the current value detected by the failed current sensor 16 becomes a value different from the current values ​​detected by the other two current sensors 16. Therefore, the fault determination unit 193 determines whether the current values ​​I1 to I3 are all the same value (step S105), and if all are the same, it is determined that all the current sensors 16-1 to 16-3 are normal (step S106). On the other hand, when the fault determination unit 193 determines that the current values ​​I1 to I3 are not the same value, it is determined that an abnormality has occurred in one of the current sensors 16-1 to 16-3 (step S107). Furthermore, the fault determination unit 193 determines that the current sensor 16 that detects the current value that is the minority among the current values ​​I1 to I3 has a fault by applying the principle of majority decision. That is, the failure determination unit 193 determines that a failure has occurred in the current sensor 16 that has detected a current value different from the other plurality of current values, among the current values ​​I1 to I3.

[0077] When the fault determination unit 193 determines that an abnormality has occurred in one of the current sensors 16-1 to 16-3, it broadcasts the fact (step S108). The broadcast may be a sound or a display. The display may be a display device showing that an abnormality has occurred, or may be a light-emitting diode (LED) lighting or flashing.

[0078] After the failure determination process by the failure determination unit 193 is completed, the charging control unit 19 stops external charging (step S109) when the battery cell groups 10-1 to 10-3 are fully charged. After stopping external charging, the charging control unit 19 connects the battery cell groups 10-1 to 10-3 in parallel (step S110).

[0079] When the fault determination unit 193 determines that no fault has occurred in any of the current sensors 16-1 to 16-3, the current detection unit 192 may detect the current value Is (for example, the current value of the charging current) by averaging the current values ​​I1 to I3 detected by the current sensors 16-1 to 16-3 during external charging.

[0080] The vehicle battery device 3 of the above-mentioned embodiment is externally charged, but it is not necessary to perform external charging. The vehicle battery device 3 only needs to have a structure that can switch multiple battery cell groups 10 and multiple battery cell groups 10 to be connected in parallel and in series, and it is not necessary to perform external charging. For example, the vehicle battery device 3 only needs to have a structure that can switch multiple battery cell groups 10 to be connected in parallel and in series, and it is also possible to charge multiple battery cell groups 10 with the power generated internally, and it is also possible to discharge the power of multiple battery cell groups 10. For example, the vehicle battery device 3 has a structure that can switch multiple battery cell groups 10 to be connected in parallel and in series, and multiple current sensors 16 are provided near the negative terminal or the positive terminal of each battery cell group 10. External charging may not be a necessary structure of the vehicle battery device 3.

[0081] As mentioned above, although the embodiment of the present invention is described in detail with reference to the drawings, the specific structure is not limited to this embodiment, and also includes the design etc. which do not deviate from the scope of the gist of the present invention.

[0082] (Variant 1)

[0083] The vehicle storage battery device 3 of the above-mentioned embodiment has three battery cell groups 10, but the number of battery cell groups is not particularly limited. The vehicle storage battery device 3 may have two or more battery cell groups 10. For example, when the number of battery cell groups 10 of the vehicle storage battery device 3 is two, the fault determination unit 193 may also be configured as follows: Figure 4 The method shown in the figure is not used to perform the fault determination process by majority decision. Figure 4 For example, it is assumed that the vehicle battery device 3 includes two battery cell groups 10 - 1 and 10 - 2 and two current sensors 16 - 1 and 16 - 2.

[0084] like Figure 4 As shown, the charging control unit 19 communicates with the external charger 1 to detect the connection (external connection) of the charging plug 17 to the vehicle 2. Thus, the charging control unit 19 authenticates the external connection (step S201). If the charging control unit 19 detects the external connection, it connects the plurality of battery cell groups 10-1 and 10-2 in series (step S202) and starts external charging (step S203).

[0085] The external charging is initially constant current charging, and then becomes constant voltage charging. During constant current charging, the charging control unit 19 communicates with the external charger 1 and obtains information on the current value of the charging current during the constant current charging, that is, the constant current value Icc from the external charger 1 (step S204). In addition, each current sensor 16-1, 16-2 detects the current values ​​I1, I2 during constant current charging (step S205). And, each current sensor 16-1, 16-2 outputs the current values ​​I1, I2 to the charging control unit 19, respectively.

[0086] If the fault determination unit 193 obtains the current values ​​I1 and I2 from each current sensor 16-1 and 16-2, it determines whether the current sensors 16-1 and 16-2 have faults based on the constant current value Icc and the current values ​​I1 and I2. For example, the fault determination unit 193 determines whether each of the current values ​​I1 and I2 is within a specified range centered on the constant current value Icc (step S206). For example, the fault determination unit 193 determines whether each of the current values ​​I1 and I2 is within ±5% of the constant current value Icc. If the fault determination unit 193 determines that each of the current values ​​I1 and I2 is within ±5% of the constant current value Icc, it determines that the current sensors 16-1 and 16-2 are normal (step S207). On the other hand, if the fault determination unit 193 determines that at least one of the current values ​​I1 and I2 is outside ±5% of the constant current value Icc, it determines that an abnormality has occurred in the current sensor 16 that detected the current value (step S208). When the failure determination unit 193 determines that an abnormality has occurred in one or more current sensors 16 , it broadcasts the abnormality in the same manner as in step S108 (step S209 ).

[0087] Thereafter, when the battery cell groups 10-1 and 10-2 are fully charged, the charging control unit 19 stops external charging (step S210). After stopping external charging, the charging control unit 19 connects the battery cell groups 10-1 and 10-2 in parallel (step S211).

[0088] (Variant 2)

[0089] The fault determination unit 193 of the above-mentioned embodiment may not use the principle of majority decision as the fault determination process. For example, the fault determination unit 193 may determine that an abnormality has occurred in the current sensor 16 when one of the current values ​​I1 to I3 exceeds a specified current value that takes into account the deviation of the detection of the current sensor 16. For example, the fault determination unit 193 may obtain the difference between the current values ​​I1 to I3 and determine that an abnormality has occurred in the current sensor 16 when the value of the difference exceeds a threshold value that takes into account the deviation of the detection of the current sensor 16.

[0090] (Variant 3)

[0091] The charging control unit 19 of the above-mentioned embodiment may also obtain the SOC of each battery cell group 10-1 to 10-3 based on the current value Is obtained by averaging the current values ​​I1 to I3. Furthermore, the charging control unit 19 may also control not to switch the battery cell groups 10-1 to 10-3 from series connection to parallel connection when a deviation of more than a predetermined range occurs in the SOC of each battery cell group 10-1 to 10-3 after the external charging is completed. Thus, the charging control unit 19 switches from series connection to parallel connection after performing cell balancing to equalize the storage capacity of the battery cell groups 10-1 to 10-3 when a deviation of more than a predetermined range occurs in the SOC of each battery cell group 10-1 to 10-3. Thus, it is possible to suppress the inrush current from flowing into the battery cell groups 10-1 to 10-3.

[0092] As described above, the vehicle battery device 3 includes a connection switch and current sensors 16-1 to 16-3. The connection switch switches the electrical connection between the plurality of battery cell groups 10-1 to 10-3 to a series connection or a parallel connection. The connection switches are a parallel connection switch 14 and a series connection switch 15. The current sensors 16-1 to 16-3 detect the current flowing through each battery cell group 10 in both the series connection and the parallel connection. Each current sensor 16-1 to 16-3 is disposed near the positive terminal T1 or the negative terminal T2 of the battery cell group 10-1 to 10-3, respectively. For example, each current sensor 16-1 to 16-3 is disposed immediately before the positive terminal T1 or the negative terminal T2 of the battery cell group 10-1 to 10-3, respectively.

[0093] With such a configuration, the vehicle battery device 3 can detect the current value Is flowing through each of the battery cell groups 10 - 1 to 10 - 3 regardless of whether the connection between the plurality of battery cell groups 10 - 1 to 10 - 3 is a series connection or a parallel connection.

[0094] In addition, for example, the current sensors 16-1 to 16-3 are provided as the above-mentioned vicinity in the current path between the positive terminal T1 or the negative terminal T2 of each battery cell group and the connection switch (for example, the series connection switch 15). And the current sensors 16-1 to 16-3 are connected between the branch point of the current path and the positive terminal T1 or the negative terminal T2.

[0095] In addition, the charging control unit 19 can also detect the current value Is flowing through each battery cell group connected in series based on the current values ​​I1 to I3 detected by each current sensor 16-1 to 16-3 when the plurality of battery cell groups 10-1 to 10-3 are connected in series. As a result, the deviation of the detection of each current sensor 16-1 to 16-3 is reduced, and the relative accuracy of the current value Is is improved. As a result, the vehicle battery device 3 can improve the calculation accuracy of the SOC and extend the cruising range of the vehicle.

[0096] In addition, the charging control unit 19 may also include a fault determination unit 193. The fault determination unit 193 may also determine whether each current sensor 16-1 to 16-3 has a fault by comparing the current values ​​detected by each current sensor 16-1 to 16-3 when the plurality of battery cell groups 10-1 to 10-3 are connected in series. Thus, the fault determination unit 193 can detect abnormalities of each current sensor 16-1 to 16-3 with a simple structure.

[0097] Industrial Applicability

[0098] According to the above-described vehicle battery device, the current flowing through each battery cell group can be detected regardless of whether the connection between the plurality of battery cell groups is a series connection or a parallel connection.

Claims

1. A vehicle battery device, comprising a first contactor, a second contactor and an inverter, characterized in that: The vehicle battery device comprises: a plurality of battery cell groups, the battery cells being connected in series; A connection switch capable of switching the electrical connection between the plurality of battery cell groups into a series connection or a parallel connection; A current sensor detects current flowing through each battery cell group in both the series connection and the parallel connection; as well as A charging control unit, including a fault determination unit, The current sensor is disposed near the positive terminal or the negative terminal of each battery cell group. The first contactor has a first contact connected to the positive terminal of the battery cell group and a second contact connected to the first input terminal of the inverter, The second contactor has a first contact connected to the negative electrode terminal of the battery cell group and a second contact connected to the second input terminal of the inverter, and When the plurality of battery cell groups are connected in series, the charging control unit performs constant current charging, and the fault determination unit determines whether each current sensor has a fault by comparing the current value of the constant current charging, i.e., the constant current value, with the current detected by each current sensor.

2. The vehicle battery device according to claim 1, wherein: The current sensor is connected to a current path between a positive terminal or a negative terminal of each of the battery cell groups and the connection switch.

3. The vehicle battery device according to claim 2, characterized in that: The current sensor is connected between the positive terminal or the negative terminal and a branch point where the current path branches.

4. The vehicle battery device according to claim 1, wherein: Also available: The charging control unit controls the connection switch to an on state or an off state to connect the plurality of battery cell groups in series, and charges each of the battery cell groups using power supplied from the outside. And the charging control unit Based on the current detected by each of the current sensors in a state where the plurality of battery cell groups are connected in series, the current flowing through each of the battery cell groups connected in series is detected.

5. The vehicle battery device according to claim 2, wherein: Also available: The charging control unit controls the connection switch to an on state or an off state to connect the plurality of battery cell groups in series, and charges each of the battery cell groups using power supplied from the outside. And the charging control unit Based on the current detected by each of the current sensors in a state where the plurality of battery cell groups are connected in series, the current flowing through each of the battery cell groups connected in series is detected.

6. The vehicle battery device according to claim 3, wherein: The charging control unit controls the connection switch to an on state or an off state to connect the plurality of battery cell groups in series, and charges each of the battery cell groups using power supplied from the outside. And the charging control unit Based on the current detected by each of the current sensors in a state where the plurality of battery cell groups are connected in series, the current flowing through each of the battery cell groups connected in series is detected.

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