On-vehicle battery system

Abstract

To provide an on-vehicle battery system that can improve the confidentiality of wireless communication related to an on-vehicle battery more than ever before.SOLUTION: A battery storage device includes one or more battery modules having a battery pack, and a management unit that manages the battery modules by wirelessly communicating with the battery modules, and the battery modules and the management unit perform the wireless communication by updating an encryption key over time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an on-board battery system. [Background technology]

[0002] Patent Document 1 below discloses an electricity storage pack. This electricity storage pack is provided in a vehicle and includes a battery module and a battery control unit, and transmits the charging state of the battery module to the vehicle control unit by wirelessly communicating with the vehicle control unit. The wireless communication between this electricity storage pack and the vehicle control unit is encrypted using a preset fixed encryption key. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 200195 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the background art, since the encryption key is fixed, there is a risk that wireless communication related to the control of the battery module may be intercepted by a third party and the content of the communication may be analyzed. In other words, in the background art, there is a concern that information related to the control of the on-board battery may be leaked to a third party, which may result in unauthorized rewriting of the program of the battery control unit or vehicle control unit, thereby disrupting the regular control of the on-board battery.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an in-vehicle battery system that can improve the confidentiality of wireless communication related to an in-vehicle battery more than ever before. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention adopts a solution relating to an on-board battery system, which comprises one or more battery modules having a battery pack, and a management unit that manages the battery modules by communicating wirelessly with the battery modules, and the battery modules and the management unit update an encryption key over time to communicate wirelessly. Effect of the Invention

[0007] According to the present invention, it is possible to provide an on-board battery system that can improve the confidentiality of wireless communication related to an on-board battery more than ever before. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a system configuration of an in-vehicle battery system according to an embodiment of the present invention; [Diagram 2] 4 is a timing chart showing a communication operation of the vehicle-mounted battery system according to one embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing an update cycle of a cryptographic key of an in-vehicle battery system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the in-vehicle battery system A according to this embodiment includes three battery modules M1-M3 and one BMS (Battery Management System) 1. In Fig. 1, the number of battery modules M1-M3 is set to three for the sake of convenience. The number of battery modules M1-M3 may be any number other than one or three.

[0010] The three battery modules M1 to M3 each include lithium ion batteries 2A to 2C and CVS (Cell Voltage Sensors) 3A to 3C. That is, the first battery module M1 includes a first lithium ion battery 2A and a first CVS 3A. The second battery module M2 includes a second lithium ion battery 2B and a second CVS 3B. The third battery module M3 includes a third lithium ion battery 2C and a third CVS 3C.

[0011] Each of the three lithium ion batteries 2A-2C is an assembled battery with multiple battery cells connected in series. These three lithium ion batteries 2A-2C are connected in series with each other. That is, the three lithium ion batteries 2A-2C constitute a secondary battery in which the three assembled batteries are connected in series, that is, a relatively high-voltage secondary battery in which many battery cells are connected in series.

[0012] The three CVSs 3A-3C are voltage detectors that detect the voltage of each battery cell in the lithium ion batteries 2A-2C as a cell voltage. That is, the first CVS 3A detects the voltage of each battery cell in the first lithium ion battery 2A as a cell voltage. The second CVS 3B detects the voltage of each battery cell in the second lithium ion battery 2B as a cell voltage. The third CVS 3C detects the voltage of each battery cell in the third lithium ion battery 2C as a cell voltage.

[0013] The three CVSs 3A to 3C each include an infrared communication unit 4A to 4C and a radio wave communication unit 5A to 5C. That is, the first CVS 3A includes a first infrared communication unit 4A and a first radio wave communication unit 5A. The second CVS 3B includes a second infrared communication unit 4B and a second radio wave communication unit 5B. The third CVS 3C includes a third infrared communication unit 4C and a third radio wave communication unit 5C.

[0014] The three infrared communication units 4A-4C are first communication units that perform wireless communication with the BMS 1 using a first communication method. The first communication method is specifically a wireless communication method that uses infrared light as a communication medium. The three infrared communication units 4A-4C perform wireless communication (infrared communication) related to setting up pairing between the BMS 1 and the three CVSs 3A-3C (the three battery modules M1-M3) based on the first communication method.

[0015] Furthermore, in addition to the wireless communication (infrared communication) related to the pairing, the three infrared communication units 4A to 4C also perform wireless communication (infrared communication) related to setting of an encryption key in wireless communication (radio communication) in the second communication method performed between the three radio communication units 5A to 5C and the BMS 1. Such wireless communication (infrared communication) based on the first communication method is performed in a first communication cycle.

[0016] That is, the first infrared communication unit 4A performs wireless communication (infrared communication) with BMS1 regarding setting up pairing between the first CVS3A (first battery module M1) and BMS1 based on the first communication method, and also performs wireless communication (infrared communication) with BMS1 regarding setting an encryption key for wireless communication using the second communication method, at a first communication period.

[0017] The second infrared communication unit 4B performs wireless communication (infrared communication) with BMS1 based on the first communication method regarding setting up pairing between the second CVS3B (second battery module M2) and BMS1, and also performs wireless communication (infrared communication) with BMS1 based on the first communication method regarding setting an encryption key for wireless communication using the second communication method, at a first communication period.

[0018] The third infrared communication unit 4C performs wireless communication (infrared communication) with BMS1 based on the first communication method regarding setting up pairing between the third CVS3C (third battery module M3) and BMS1, and also performs wireless communication (infrared communication) with BMS1 based on the first communication method regarding setting an encryption key for wireless communication using the second communication method, at a first communication period.

[0019] The three radio wave communication units 5A-5C are second communication units that perform wireless communication with the BMS 1 in a second communication method different from the above-mentioned first communication method. The second communication method is specifically a wireless communication method that uses radio waves as a communication medium. The wireless communication (radio wave communication) between the three radio wave communication units 5A-5C and the BMS 1 in the second communication method is performed in a second communication cycle that is asynchronous with the first communication cycle.

[0020] That is, the first radio wave communication unit 5A performs radio communication (radio wave communication) regarding the cell voltage of the first lithium ion battery 2A with the BMS 1 based on the second communication method. The second radio wave communication unit 5B performs radio communication (radio wave communication) regarding the cell voltage of the second lithium ion battery 2B with the BMS 1 based on the second communication method. The third radio wave communication unit 5C performs radio communication (radio wave communication) regarding the cell voltage of the third lithium ion battery 2C with the BMS 1 based on the second communication method.

[0021] The BMS1 is a management unit that includes an infrared communication unit 6 and a radio wave communication unit 7, and manages the three battery modules M1 to M3 by wirelessly communicating with the three battery modules M1 to M3. That is, the BMS1 comprehensively manages (controls) the three battery modules M1 to M3 based on a predetermined management program.

[0022] The infrared communication unit 6 is a first communication unit that performs wireless communication (infrared communication) with the three infrared communication units 4A to 4C based on the first communication method. That is, the infrared communication unit 6 and the above-mentioned three infrared communication units 4A to 4C are the first communication unit in this embodiment.

[0023] By using infrared rays as a communication medium, the infrared communication unit 6 performs wireless communication (infrared communication) regarding the pairing between the BMS1 and the three CVS 3A to 3C (three battery modules M1 to M3), and also performs wireless communication (infrared communication) regarding the setting of an encryption key for wireless communication (radio communication) of the second communication method between the radio communication unit 7 and the three radio communication units 5A to 5C.

[0024] That is, based on a first communication method using infrared light as a communication medium, the infrared communication unit 6 performs wireless communication (infrared communication) regarding pairing between the BMS1 and the first CVS3A (first battery module M1), and also performs wireless communication (infrared communication) regarding setting an encryption key for wireless communication (radio communication) of the second communication method between the first radio wave communication unit 5A and the radio wave communication unit 7.

[0025] In addition, the infrared communication unit 6 performs wireless communication (infrared communication) regarding pairing between the BMS1 and the second CVS3B (second battery module M2) based on the first communication method using infrared as a communication medium, and also performs wireless communication (infrared communication) regarding setting an encryption key for wireless communication (radio communication) of the second communication method between the second radio wave communication unit 5B and the radio wave communication unit 7.

[0026] Furthermore, the infrared communication unit 6 performs wireless communication (infrared communication) regarding pairing between the BMS1 and the third CVS3C (the third battery module M3) based on the first communication method using infrared as the communication medium, and also performs wireless communication (infrared communication) regarding setting the encryption key for wireless communication (radio communication) of the second communication method between the third radio wave communication unit 5C and the radio wave communication unit 7.

[0027] Here, the encryption key is a secret code for encrypting wireless communication by the second communication method between the three radio wave communication units 5A to 5C and the radio wave communication unit 7. This encryption key is generated by, for example, a random number generator provided in the BMS 1. The infrared communication unit 6 performs an initial setting process of the encryption key during a process of setting up pairing with the three infrared communication units 4A to 4C.

[0028] After the encryption key initial setting process, the infrared communication unit 6 performs wireless communication (infrared communication) with the three infrared communication units 4A to 4C in a first communication cycle, thereby sequentially updating the encryption key. That is, the first communication cycle T between the infrared communication unit 6 and the three infrared communication units 4A to 4C is set as an encryption key update cycle T.

[0029] The encryption key update period T is set based on the cell voltage transmission period Ta between the three radio wave communication units 5A-5C and the radio wave communication unit 7. In other words, the encryption key update period T is set to, for example, an integer multiple of the cell voltage transmission period Ta.

[0030] The radio wave communication unit 7 is a second communication unit that performs wireless communication with the three radio wave communication units 5A to 5C based on the second communication method. The radio wave communication unit 7 uses radio waves as a communication medium to perform wireless communication (radio wave communication) regarding the cell voltages of the three lithium ion batteries 2A to 2C with the three radio wave communication units 5A to 5C.

[0031] That is, the radio wave communication unit 7 sequentially receives the cell voltages of each battery cell of the first lithium ion battery 2A (first battery module M1) at a transmission period Ta through wireless communication (radio wave communication) with the first radio wave communication unit 5A based on the second communication method.

[0032] In addition, the radio wave communication unit 7 sequentially receives the cell voltages of each battery cell of the second lithium ion battery 2B (second battery module M2) at a transmission period Ta through wireless communication (radio wave communication) with the second radio wave communication unit 5B based on the second communication method.

[0033] Furthermore, the radio wave communication unit 7 sequentially receives the cell voltages of each battery cell of the third lithium ion battery 2C (third battery module M3) at a transmission period Ta through wireless communication (radio wave communication) with the third radio wave communication unit 5C based on the second communication method.

[0034] Next, the operation of the in-vehicle battery system A according to this embodiment will be described in detail with reference to FIGS.

[0035] 2(a), in the steady state of the in-vehicle battery system A, the BMS 1 and the three CVSs 3A to 3C perform infrared communication at a first communication cycle (update cycle T) by using the first communication units (infrared communication units 4A to 4C, 6). By this infrared communication, the encryption key for the radio communication is updated to different values ​​in sequence at each update cycle T, such as encryption key X1 → encryption key X2 → encryption key X3 → encryption key X4, ... as shown in the figure.

[0036] That is, the BMS 1 transmits a newly generated random number using the infrared communication unit 6 to each of the infrared communication units 4A-4C of the three CVSs 3A-3C as an encryption key to be used in radio wave communication within the next update period T. The three CVSs 3A-3C internally store the encryption keys received by the three infrared communication units 4A-4C, respectively.

[0037] Then, when the radio communication units 5A-5C receive request signals Y1, Y2, Y3, ... using radio communication from the radio communication unit 7 of the BMS 1, the three CVSs 3A-3C transmit (reply) the cell voltages for each battery cell of the lithium ion batteries 2A-2C to the radio communication unit 7 of the BMS 1. The request signals Y1, Y2, Y3, ... are transmitted from the radio communication unit 7 to the three radio communication units 5A-5C in the same period as the above-mentioned transmission period Ta. Therefore, the cell voltages for each battery cell of the lithium ion batteries 2A-2C are transmitted to the radio communication unit 7 in each transmission period Ta as voltage signals Z1, Z2, Z3, ... encrypted using an encryption key.

[0038] Here, when the in-vehicle battery system A is started up, a pairing process is performed by infrared communication between the BMS 1 and the three CVSs 3A to 3C. That is, when the BMS 1 is started up, it completes pairing by transmitting and receiving information required for mutual pairing (pairing information) to and from the infrared communication units 4A to 4C of the three CVSs 3A to 3C using the infrared communication unit 6.

[0039] In such an in-vehicle battery system A, for example as shown in Fig. 2(b), if an unauthorized CVS that has unauthorizedly decrypted encryption key X1 transmits false voltage signals D3, D4, D5, ... to the radio communication unit 7 to the BMS1, the false voltage signals D5, D6, D7, ... other than the false voltage signals D3 and D4 will not be correctly decrypted by the BMS1. In other words, the false voltage signals D5, D6, D7, ... are not encrypted by encryption keys X2, X3, X4, ... that are different from the encryption key X1, and therefore will not be correctly decrypted by the BMS1.

[0040] 3, when a 32-bit code (random number) is used as the encryption key and the update period (acquisition period) of the cell voltage is 10 ms, the probability that the BMS1 acquires a false voltage signal depends on the encryption key update period T. In other words, the shorter the encryption key update period T, the smaller the probability of acquiring a false voltage signal.

[0041] Therefore, according to this embodiment, the BMS1 (management unit) and the three battery modules M1 to M3 update the encryption key over time and perform radio communication (wireless communication), making it possible to provide an in-vehicle battery system A that can improve the confidentiality of wireless communication related to the in-vehicle battery more than ever before.

[0042] In addition, the in-vehicle battery system A of this embodiment includes the battery modules M1 to M3 and BMS1 (management unit), infrared communication units 4A to 4C, 6 (first communication unit) that perform infrared communication (wireless communication) regarding the setting of the encryption key using a first communication method, and radio communication units 5A to 5C, 7 (second communication unit) that perform radio communication (wireless communication) regarding the cell voltage other than the setting of the encryption key using a second communication method different from the first communication method.

[0043] In other words, according to this embodiment, the wireless communication regarding the setting of the encryption key and the wireless communication regarding the cell voltage are performed using different communication methods, which also makes it possible to improve the confidentiality of the wireless communication regarding the in-vehicle battery more than ever before.

[0044] Furthermore, according to this embodiment, the infrared communication units 4A-4C, 6 (first communication units) and the radio wave communication units 5A-5C, 7 (second communication units) perform wireless communication asynchronously, which also makes it possible to improve the confidentiality of wireless communication related to the in-vehicle battery more than ever before.

[0045] Furthermore, in the vehicle-mounted battery system A according to this embodiment, the infrared communication units 4A-4C and 6 (first communication unit) use infrared rays as a communication medium, and the radio wave communication units 5A-5C and 7 (second communication unit) use radio waves as a communication medium. According to this embodiment, the first communication unit and the second communication unit use different communication media, which also makes it possible to improve the confidentiality of wireless communication related to the vehicle-mounted battery compared to the conventional technology.

[0046] Furthermore, in the in-vehicle battery system A according to this embodiment, the battery modules M1-M3 sequentially transmit the cell voltages in the assembled battery to the BMS1 (management unit) using wireless communication at a predetermined communication cycle Ta, and the encryption key update cycle T is set based on the cell voltage communication cycle Ta. According to this embodiment, it is possible to improve the confidentiality of wireless communication regarding the cell voltages of the battery modules M1-M3 more than ever before.

[0047] [Appendix 1] One or more battery modules including a battery pack; a management unit that manages the battery module by wirelessly communicating with the battery module; The vehicle-mounted battery system is characterized in that the battery module and the management unit perform the wireless communication by updating an encryption key over time.

[0048] [Appendix 2] The battery module and the management unit are a first communication unit that performs the wireless communication related to the setting of the encryption key in a first communication method; a second communication unit that performs the wireless communication other than the setting of the encryption key in a second communication method different from the first communication method; 2. An on-board battery system according to claim 1, comprising:

[0049] [Appendix 3] 3. The in-vehicle battery system according to claim 2, wherein the first communication unit and the second communication unit perform the wireless communication asynchronously.

[0050] [Appendix 4] the first communication unit uses infrared rays as a communication medium; 4. The in-vehicle battery system according to claim 2 or 3, wherein the second communication unit uses radio waves as a communication medium.

[0051] [Appendix 5] the battery module sequentially transmits cell voltages in the assembled battery to the management unit at a predetermined communication period using the wireless communication; 5. The vehicle-mounted battery system according to claim 1, wherein the encryption key update cycle is set based on the communication cycle. [Explanation of symbols]

[0052] A. Vehicle battery system M1~M3 Battery Modules 1 BMS(Battery Management System) 2A~2C Lithium-ion battery 3A~3C CVS(Cell Voltage Sensor) 4A to 4C, 6 Infrared communication unit (first communication unit) 5A to 5C, 7 Radio communication unit (second communication unit)

Claims

1. One or more battery modules including a battery pack; a management unit that manages the battery module by wirelessly communicating with the battery module; The vehicle-mounted battery system is characterized in that the battery module and the management unit perform the wireless communication by updating an encryption key over time.

2. The battery module and the management unit are a first communication unit that performs the wireless communication related to the setting of the encryption key in a first communication method; a second communication unit that performs the wireless communication other than the setting of the encryption key in a second communication method different from the first communication method; The vehicle-mounted battery system according to claim 1 ,

3. 3. The vehicle-mounted battery system according to claim 2, wherein the first communication unit and the second communication unit perform the wireless communication asynchronously.

4. the first communication unit uses infrared rays as a communication medium; 4. The vehicle-mounted battery system according to claim 2, wherein the second communication unit uses radio waves as a communication medium.

5. the battery module sequentially transmits cell voltages in the assembled battery to the management unit at a predetermined communication period using the wireless communication; 3. The vehicle-mounted battery system according to claim 1, wherein the encryption key update period is set based on the communication period.

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