Vehicle battery system with energy storage

Abstract

A vehicle battery system is provided. The system includes a battery assembly having a first battery module and a second battery module, a relay installed between contacts connected to respective terminals of the first battery module and the second battery module and controlling power supply to a drive motor of a vehicle, a converter converting voltage input from the first battery module and the second battery module and supplying the converted voltage to low-voltage electronic components, an energy storage section connected to an output of the converter, and a battery management system controlling the above components.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2020-0122625, filed on September 22, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a vehicle battery system. Background Technology

[0004] Typically, environmentally friendly vehicles (hybrid vehicles, electric vehicles, fuel cell vehicles, etc.) equipped with electric motors that provide driving force for the wheels have high-voltage batteries to provide high-voltage energy to drive the electric motors.

[0005] Here, high voltage generally refers to a voltage that is relatively higher than the voltage of the battery (which typically has a voltage of 11 to 14V) supplied to start the engine and drive the vehicle or to power the loads of electronic components.

[0006] Therefore, environmentally friendly vehicles typically consist of separate high-voltage batteries for driving the electric motor and low-voltage batteries for powering the electronic loads. Managing these independent power systems by separating the high-voltage and low-voltage batteries not only results in a bloated system but also in significant efficiency losses.

[0007] To address this issue, considering that a battery assembly is implemented by multiple units or modules, a high-voltage-low-voltage integrated system is proposed, in which a portion of the multiple battery modules constituting a high-voltage battery is used to provide low-voltage power.

[0008] However, the previously proposed high-voltage-low-voltage integrated systems can lead to an imbalance in the state of charge among multiple battery modules set in a single battery pack, resulting in deterioration in system efficiency or robustness and vehicle instability.

[0009] Previously proposed high-voltage-low-voltage integrated systems also face the risk of instantaneous insulation breakdown when controlling high-voltage-low-voltage relays according to vehicle driving conditions. Summary of the Invention

[0010] The present invention provides a configuration of a vehicle battery system to improve system efficiency and robustness by addressing the imbalance of charging states among multiple battery modules disposed in a battery assembly, and to prevent potentially instantaneous insulation breakdown when controlling high-voltage-low-voltage relays according to vehicle driving conditions.

[0011] An exemplary embodiment of the present invention provides a vehicle battery system having an energy storage unit. The system is configured to include a battery assembly having a first battery module and a second battery module, a relay installed between contacts connected to the terminals of the first battery module and the second battery module and controlling the power supply to the drive motor of the vehicle, a converter that converts the voltage input from the first battery module and the second battery module and supplies the converted voltage to low-voltage electronic components, an energy storage unit connected to the output terminal of the converter, and a battery management system that controls the above components.

[0012] According to an exemplary embodiment of the present invention, a vehicle battery system with an energy storage unit prevents transient insulation breakdown that occurs when driving a relay by adding the energy storage unit to the LDC output terminal, and enables the vehicle to operate even in fail-safe conditions such as LDC failure, thereby improving vehicle reliability and safety. Attached Figure Description

[0013] Figure 1 This is a configuration diagram of a vehicle battery system of one form disclosed herein.

[0014] Figure 2 This is a flowchart illustrating the operation of a vehicle battery system in vehicle startup mode, as disclosed herein.

[0015] Figure 3A and Figure 3B This is a flowchart illustrating the operation of switching from a state of joint use of the first and second battery modules to a state of independent use of the second battery module. Figure 3C This is a flowchart illustrating the operation of switching from the standalone use of the second battery module to the combined use of the first and second battery modules.

[0016] Figure 4 This is a flowchart illustrating the operation of a vehicle battery system in an external charging mode of the vehicle, as disclosed herein.

[0017] Figure 5A This is a flowchart illustrating the operation of switching from the shared use state of the first and second battery modules to the key-off state. Figure 5B This is a flowchart illustrating the operation of switching from the standby mode of the second battery module to the engine off mode.

[0018] Figure 6 This is a flowchart illustrating the operation of a vehicle battery system in the vehicle's supplemental charging mode, as disclosed herein.

[0019] Figure 7 This is a configuration diagram of a vehicle battery system of one form disclosed herein. Detailed Implementation

[0020] The configuration and operation of the vehicle battery system with an energy storage unit according to the present invention will be described in detail below with reference to the accompanying drawings.

[0021] However, the disclosed drawings are provided as examples to allow those skilled in the art to fully understand the spirit of the invention. Therefore, the invention is not limited to the drawings presented below, but can be embodied in other aspects.

[0022] Unless otherwise specified, the terminology used in this specification has the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and detailed descriptions of known functions and configurations that may unnecessarily obscure the spirit of the invention are omitted in the following specification and drawings.

[0023] Figure 1 These are configuration diagrams of some forms of vehicle battery systems according to the present invention.

[0024] Reference Figure 1 According to an exemplary embodiment of the present invention, a vehicle battery system is configured to include a battery assembly 10 consisting of multiple battery modules, a motor control unit (MCU) 20, a drive motor 30, a converter 40, low-voltage electronic components 50, a charging unit 60, a battery management system (BMS) 70, an energy storage unit 80, and multiple relays R1, R2, R3, R4, R5, R6, and R7.

[0025] The battery assembly 10, which has multiple battery modules 11 and 12 connected in series with each other, has a single package form in appearance.

[0026] According to an exemplary embodiment of the present invention, the battery assembly 10 includes a first battery module 11 and a second battery module 12.

[0027] In this case, the first battery module 11 is shown as a single battery module, but it can also be implemented by multiple battery modules with the same capacity and connected in series, and the second battery module 12 is shown as multiple battery modules M1 to M11, but it can also be implemented by a single battery module.

[0028] The first battery module 11 is a battery module whose output voltage amplitude (e.g., DC 12V) corresponds to the power of the low-voltage electronic component load of the vehicle. It can function as a low-voltage battery and has a larger capacity than the second battery module 12.

[0029] Conversely, the second battery module 12 is a battery module whose output voltage amplitude (e.g., DC 200 to 300V) corresponds to the power required to drive the drive motor 30 of the vehicle.

[0030] Here, the capacity of the battery module, i.e. the maximum energy that can be stored in the battery module, is determined based on the number of battery cells included in the battery module during manufacturing.

[0031] When the first battery module 11 is composed of multiple battery modules, the capacity of each battery module is preferably the same as that of the others. In the case of the second battery module 12, the capacity of each battery module is preferably the same as that of the others.

[0032] The circuit connection state of the battery system according to the present invention will be described.

[0033] First, one contact p1 of the second battery module 12 is connected to the first contact a, and another contact p2 is connected to the second contact b. The other contact p4 of the first battery module 11 is connected to the third contact c.

[0034] The third relay R3 is electrically connected between another contact p2 of the second battery module 12 and a contact p3 of the first battery module 11. Therefore, depending on the operation of the third relay R3, the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11 are either closed or opened.

[0035] The first relay R1 is electrically connected between the first contact a connected to one contact p1 of the second battery module 12 and the second contact b connected to another contact p2. Therefore, according to the operation of the first relay R1, the first relay node N1, which is the input terminal of the first relay R1, is connected to the first contact a and the first relay node N1 and the second contact b are disconnected from each other, or the first relay node N1 and the first contact a are disconnected from each other and the first relay node N1 and the second contact b are connected to each other.

[0036] The second relay R2 is electrically connected between the second contact b, which is connected to another contact p2 of the second battery module 12, and the third contact c, which is connected to another contact p4 of the first battery module 11. Therefore, according to the operation of the second relay R2, the second relay node N2, which is the input terminal of the second relay R2, and the second contact b are connected to each other and the second relay node N2 and the third contact c are disconnected from each other, or the second relay node N2 and the second contact b are disconnected from each other and the second relay node N2 and the third contact c are connected to each other.

[0037] When the first relay R1 is not connected to either the first contact a or the second contact b, the first relay node N1 is in a floating state, and when the second relay R2 is not connected to either the second contact b or the third contact c, the second relay node N2 is in a floating state.

[0038] The first relay node N1 and the second relay node N2 are respectively connected to the inverter (DC-AC converter) that converts battery power and supplies it to the drive motor 30 that drives the vehicle, or to the input terminal of the motor control unit 20 with the inverter.

[0039] The fourth relay R4 is electrically connected between the second relay node N2 and the charging unit 60, which receives power from the outside and converts the corresponding power into power to charge the battery and provides the converted power. Thus, according to the operation of the fourth relay R4, the charging unit 60 and the second relay node N2 are connected or disconnected from each other.

[0040] The fifth relay R5 is electrically connected between the first relay node N1 and the charging unit 60, so that the charging unit 60 and the first relay node N1 are connected or disconnected from each other according to the operation of the fifth relay R5.

[0041] The input terminal 43 of the converter 40, which converts high-voltage power to low-voltage power and supplies the converted low-voltage power to the low-voltage electronic component 50, is connected to each of the first relay node N1 and the second relay node N2.

[0042] The converter 40 converts the high voltage applied from the battery assembly 10 into a low voltage and provides the low voltage to the relays R1, R2, R3, R4, R5, R6, R7 and the low-voltage electronic components 50 as their operating power or to provide a charging voltage for charging the first battery module 11 included in the battery assembly 10.

[0043] In this case, the converter 40 according to an exemplary embodiment of the present invention includes a low-voltage DC-DC converter (LDC) 41 that converts DC high voltage to DC low voltage and a solar DC-DC converter (SDC) 42 that converts the power provided by the solar cells installed in the vehicle into DC low voltage.

[0044] The third relay R3 is electrically connected between another contact p2 of the second battery module 12 and a contact p3 of the first battery module 11, so that, according to the operation of the third relay R3, the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11 are connected or disconnected from each other.

[0045] The sixth relay R6 is electrically connected between one contact p3 of the first battery module 11 and the ground terminal GND, and the seventh relay R7 is electrically connected between another contact p4 of the first battery module 11 and the output terminal of the converter 40.

[0046] The sixth relay R6 and the seventh relay R7 are relays used to determine the electrical connection status of the two ends of the first battery module 11 that supplies low-voltage power.

[0047] According to the battery system of the present invention, the energy storage unit 80 is connected to the output terminal 44 of the converter 40.

[0048] The energy storage unit 80 may employ a small battery or capacitor and operate as an auxiliary power source for the battery system of the present invention to prevent momentary insulation breakdown when driving the relay and to perform fail-safe operation to enable vehicle operation when the converter 40 is disabled.

[0049] The battery system according to the present invention includes a battery management system (BMS) 70 that controls the aforementioned relays R1, R2, R3, R4, R5, R6, R7, battery assembly 10, motor control unit 20, converter 40, low-voltage electronic components 50, and charging unit 60 based on vehicle status.

[0050] The battery management system 70 controls the operation of the first to seventh relays R1, R2, R3, R4, R5, R6, R7 and the energy storage unit 80 by considering the vehicle's state, such as whether the vehicle is started, whether it is driving, whether it is charging, whether it is turned off, whether it is being recharged, as well as the state of charge (SOC) and energy storage of the first battery module 11 and the second battery module 12.

[0051] Meanwhile, preferably, the first relay R1, the second relay R2, the third relay R3, the fourth relay R4 and the fifth relay R5 are high-voltage relays with high rated voltage, which are installed on the high-voltage power line of the drive motor 30 for driving the vehicle, while the sixth relay R6 and the seventh relay R7 are low-voltage relays with low rated voltage, which are used to control the two ends of the first battery module 11 with a lower voltage.

[0052] Next, the operation of the battery system according to the present invention configured as described above will be described as a modified method.

[0053] 1. Operation of the battery system according to the present invention in startup mode

[0054] Figure 2 This is a flowchart illustrating the operation of some forms of vehicle battery systems in vehicle start-up mode.

[0055] The operation of the vehicle in the start-up mode refers to the operation of the battery system according to the present invention from starting the vehicle from the off state when the vehicle is not started until the vehicle begins to drive.

[0056] First, when the vehicle is in the off state (Sl), the first relay node N1 of the first relay R1 and the second relay node N2 of the second relay R2 are in a floating state, the third relay R3 is in an open state between the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11, and the sixth relay R6 and the seventh relay R7 are closed at both ends to connect the first battery module 11 contact p3 to the ground terminal (GND) and connect the other contact p4 of the first battery module 11 to the output terminal of the converter 40 in the initial state.

[0057] The battery management system 70 determines whether to supply power by sharing the first battery module 11 and the second battery module 12 or by using only the second battery module 12 (S2).

[0058] Whether a battery module is used in step S2 of an exemplary embodiment of the present invention can be determined by judging the energy capacity of the first battery module 11.

[0059] That is, the battery management system 70 determines whether the energy capacity of the first battery module 11 is equal to or greater than a predetermined reference capacity. When the energy capacity of the first battery module 11 is equal to or greater than the reference capacity, the battery management system 70 uses the first battery module 11 and the second battery module 12. When the energy capacity of the first battery module 11 is less than the reference capacity, the battery management system 70 uses only the second battery module 12 other than the first battery module 11.

[0060] Therefore, in step S2, when it is determined that the energy capacity of the first battery module 11 is equal to or greater than the predetermined reference capacity and the first battery module 11 and the second battery module 12 are used, the battery management system 70 connects the first relay node N1 and the first contact a of the first relay R1 to each other, and connects the second relay node N2 and the second contact b of the second relay R2 (S3).

[0061] In this situation, one contact p1 and another contact p2 of the second battery module 12 are connected to the first contact a and the second contact b, respectively, while the two ends of the third relay R3 remain in the open state.

[0062] Next, the battery management system 70 disconnects the two ends of the sixth relay R6 and the seventh relay R7 (S4), and then closes the two ends of the third relay R3 to connect another contact p2 of the second battery module 12 and a contact p3 of the first battery module 11 to each other (S5).

[0063] If the third relay R3 is closed while the ends of the sixth relay R6 and the seventh relay R7 are closed to each other, insulation breakdown may occur between the low-voltage line of the first battery module and the high-voltage line of the second battery module 12 at the moment the ends of the third relay R3 are closed. Therefore, the ends of the sixth relay R6 and the seventh relay R7 are disconnected, and then the ends of the third relay R3 are closed to each other to prevent insulation breakdown.

[0064] The battery management system 70 applies power from the energy storage unit 80 to the second relay R2 to connect the second relay node N2 of the second relay R2 to the third contact c (S6), thereby applying power from the first battery module 11 and the second battery module 12 to the motor control unit 20.

[0065] In step S2, when it is determined that the energy capacity of the first battery module 11 is less than the predetermined reference capacity and only the second battery module 12 is used, the battery management system 70 connects the first relay node N1 and the first contact a of the first relay R1 and connects the second relay node N2 and the second contact b of the second relay R2 (S7) so as to apply only the power of the second battery module 12 to the motor control unit 20.

[0066] Therefore, when the battery system of the present invention is operated in startup mode and powered by both the first battery module 11 and the second battery module 12, the two ends of the sixth relay R6 and the seventh relay R7 are disconnected (S4), and then the two ends of the third relay R3 are controlled to close, so as to prevent the insulation breakdown problem between the low voltage line of the first battery module 11 and the high voltage line of the second battery module 12.

[0067] 2. Operation of the battery system according to the present invention in driving mode

[0068] Figure 3A and Figure 3B This is a flowchart illustrating the operation of switching from a state of joint use of the first and second battery modules to a state of independent use of the second battery module. Figure 3C This is a flowchart illustrating the operation of switching from the standalone use of the second battery module to the combined use of the first and second battery modules.

[0069] The operation of the vehicle in driving mode refers to the operation of the battery system according to the present invention when the vehicle is started and in motion.

[0070] Reference Figure 3A and Figure 3BAn exemplary embodiment of the operation is described, which describes the switching from a state of joint use of the first battery module and the second battery module (hereinafter, for the convenience of description, referred to as the "common use state of the modules") to a state of independent use of the second battery module (hereinafter, for the convenience of description, referred to as the "independent use state of the second battery module").

[0071] When the converter 40, which supplies the 12V operating voltage to the low-voltage electronic components 50 and the battery management system 70, malfunctions while the vehicle is in operation, the system switches from a shared module usage state to a second battery module-only usage state, with the first battery module 11 replacing the faulty converter 40 to supply the 12V operating voltage to the low-voltage electronic components 50.

[0072] When switching from a shared module usage state to a second battery module standalone usage state, if the capacity deviation of the first battery module 11 exceeds the allowable range, the shared module usage state is switched to the second battery module standalone usage state to avoid restricting the use of the second battery module 12.

[0073] This invention illustrates two exemplary embodiments for switching from a shared module usage state to a second battery module usage state. First, referring to... Figure 3A The first exemplary embodiment is described.

[0074] Reference Figure 3A When the vehicle is in motion and the modules are in common use, as referred to Figure 2 As described, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the third contact c, and the two ends of the third relay R3 are closed. Therefore, the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11 are connected to each other, and the two ends of the sixth relay R6 and the seventh relay R7 are disconnected (S10).

[0075] In this state, the battery management system 70 determines whether it is necessary to switch from the shared use state of the modules to the independent use state of the second battery module during vehicle operation (S11).

[0076] The decision on whether to switch can be made in the case of a failure of converter 40 as described above, or in the case of a capacity deviation of the first battery module 11 exceeding the allowable range.

[0077] When it is necessary to switch to the state of using the second battery module alone in step S11, the battery management system 70 operates the second relay R2 by supplying power from the energy storage unit 80 to the second relay R2 to connect the second relay node N2 and the second contact b of the second relay (S12).

[0078] The reason for using the power of the energy storage unit 80 here is that the low-voltage converter 40 has failed and there is no power supply for operating the relay, so the power available in the energy storage unit 80 is used.

[0079] Next, the battery management system 70 disconnects the two ends of the third relay R3 by operating the third relay R3 (S13) to release the connection between one contact p3 and the second contact b of the first battery module 11, thereby supplying power to the motor control unit 20 only from the second battery module 12 and ensuring the insulation between the low-voltage line of the first battery module 11 and the high-voltage line of the second battery module 12.

[0080] Here, when operating the second relay R2, the relay operating power provided by the energy storage unit 80 is required to connect the second relay node N2 and the second contact b, while disconnecting the third relay R3 only requires removing the voltage applied to both ends of the third relay R3, so no separate relay operating power is required.

[0081] Subsequently, the battery management system 70 closes the two ends of the sixth relay R6 and the seventh relay R7, which are in the open state, respectively (S14), so as to drive the low-voltage electronic component 50 by supplying power from the first battery module 11 to the low-voltage electronic component 50.

[0082] Next, refer to Figure 3B The following describes a second exemplary embodiment of the invention, which involves switching from a state of shared use of the modules to a state of sole use of the second battery module.

[0083] First, similar to the first exemplary embodiment, refer to Figure 3B The described switch from the shared use state of the modules to the independent use state of the second battery module is performed when the converter 40 malfunctions or when the capacity deviation of the first battery module 11 exceeds the allowable range.

[0084] Reference Figure 3B When the vehicle is in motion and in a state of shared use of modules, as in the first exemplary embodiment, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the third contact c, and the two ends of the third relay R3 are closed. Therefore, the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11 are connected to each other, and the two ends of the sixth relay R6 and the seventh relay R7 are disconnected (S20).

[0085] In this state, the battery management system 70 determines whether it is necessary to switch from the shared use state of the modules to the independent use state of the second battery module during vehicle operation (S21).

[0086] The decision on whether to switch can be made in the case of a failure of converter 40 as described above, or in the case of a capacity deviation of the first battery module 11 exceeding the allowable range.

[0087] When it is necessary to switch to the state of using the second battery module alone in step S21, the battery management system 70 disconnects the two ends of the second relay R2 and the two ends of the third relay R3 by disconnecting the connection state of the second relay node N2 and the third contact c of the second relay R2 (S22), so as to disconnect the connection between one contact p3 of the first battery module 11 and the second contact b.

[0088] The battery management system 70 supplies power from the energy storage unit 80 to the sixth relay R6 and the seventh relay R7 respectively, so as to close the two ends of the sixth relay R6 and the seventh relay R7 which are in the open state (S23).

[0089] The reason for using the power of the energy storage unit 80 is that the low-voltage converter 40 has malfunctioned and there is no power supply for operating the relay, so the power available in the energy storage unit 80 is used.

[0090] Next, the battery management system 70 operates the second relay R2 by supplying power to the second relay R2 to connect the second relay node N2 and the second contact b of the second relay R2 (S24), thereby supplying power to the motor control unit 20 only from the second battery module 12 and ensuring the insulation between the low-voltage line of the first battery module 11 and the high-voltage line of the second battery module 12.

[0091] According to a second exemplary embodiment of the present invention, the switching from the shared use state of the modules to the standby use state of the second battery module is an exemplary embodiment in which the sixth relay R6 and the seventh relay R7, which operate at a lower voltage, are operated using the power of the energy storage unit 80. A small capacity energy storage unit can be configured. However, compared with the first embodiment, the second relay node N2 and the second contact b of the second relay R2 are connected later. Therefore, compared with the first exemplary embodiment, the time for supplying power from the second battery module 12 to the motor control unit 20 is relatively delayed.

[0092] Next, we will refer to Figure 3C This describes the operation of switching from a state where the second battery module is used alone to a state where the first and second battery modules are used together.

[0093] First, refer to Figure 3C The described switch from the standby mode of the second battery module to the shared mode of the modules is, in reference to Figure 3A and Figure 3BIn the exemplary embodiment described, after the converter 40 malfunctions and the malfunction of the converter 40 is resolved and the converter 40 resumes normal operation, or after the energy capacity of the first battery module 11 is balanced and the capacity deviation of the first battery module 11 returns to the allowable range, the system switches from the state of using the second battery module alone to the state of using both the first battery module 11 and the second battery module 12 together.

[0094] Reference Figure 3C When the vehicle is in motion and the second battery module is used alone, as described in the exemplary embodiment above, the first relay node N1 of the first relay R1 is connected to the first contact a (see the operation of steps S10 and S20), the second relay node N2 of the second relay R2 is connected to the second contact b (see the operation of steps S12 and S23), the two ends of the third relay R3 are in an open state (see the operation of steps S13 and S22), and the two ends of the sixth relay R6 and the seventh relay R7 are in a closed state (see the operation of steps S14 and S23) (S30).

[0095] In this state, the battery management system 70 determines whether it is necessary to switch from the state of using the second battery module alone to the state of using the modules together during vehicle operation (S31).

[0096] The determination of whether switching is required can be made as described above, in the case where the fault of converter 40 is cleared and converter 40 is operating normally, or in the case where the energy capacity of the first battery module 11 is balanced and the capacity deviation of the first battery module 11 returns to the allowable range.

[0097] When it is necessary to switch to the module co-use state in step S31, in order to avoid insulation breakdown between the low voltage line of the first battery module 11 and the high voltage line of the second battery module 12, the battery management system 70 disconnects the two ends of the sixth relay R6 and the seventh relay R7 (S32), and then connects the second relay node N2 to the third contact c by applying the power of the energy storage unit 80 to the second relay R2, and closes the two ends of the third relay R3 by applying the power of the energy storage unit 80 to the third relay R3 to connect the other contact p2 of the second battery module 12 and one contact p3 of the first battery module 11 to each other (S33).

[0098] Here, the reason why the battery management system 70 first disconnects the two ends of the sixth relay R6 and the seventh relay R7 in step S32 is that if the third relay R3 is closed while the two ends of the sixth relay R6 and the seventh relay R7 are closed to each other, an insulation breakdown may occur between the low-voltage line of the first battery module 11 and the high-voltage line of the second battery module 12 at the moment the two ends of the third relay R3 are closed.

[0099] Therefore, according to the above operation, when it is necessary to switch to the module co-use state, the second battery module's standalone use state is switched to the module co-use state of the first and second battery modules.

[0100] Meanwhile, the capacity balancing operation of the energy capacity of the first battery module 11 will be described below.

[0101] The capacity balancing of the first battery module 11 refers to comparing the energy storage capacity of the first battery module 11 and the second battery module 12, and operating such that the difference between the energy storage capacity of the first battery module 11 and the second battery module 12 becomes a predetermined reference value.

[0102] Specifically, the battery management system 70 determines whether the value of the energy storage of the first battery module 11 minus the energy storage of the second battery module 12 is equal to a predetermined energy storage reference value A, and terminates the capacity balancing operation when the value of the energy storage of the first battery module 11 minus the energy storage of the second battery module 12 is equal to the predetermined energy storage reference value A.

[0103] However, when the energy storage capacity of the first battery module 11 minus the energy storage capacity of the second battery module 12 is less than a predetermined energy storage reference value A, the battery management system 70 connects the first relay node N1 of the first relay R1 to the first contact a, connects the second relay node N2 of the second relay R2 to the second contact b, and closes the sixth relay R6 and the seventh relay R7. Therefore, the converter 40 charges the first battery module 11 using the energy stored in the second battery module 12. The first battery module 11 is charged until the energy storage capacity of the first battery module 11 minus the energy storage capacity of the second battery module 12 equals the energy storage reference value A. Here, since the capacity of the first battery module 11 is greater than that of a single battery module in the second battery module 12, it operates as a high-voltage battery together with the second battery module 12 included in the battery assembly 10 and as a low-voltage battery for driving the low-voltage electronic components 50. Therefore, it is preferable to keep the capacity difference between the battery modules on both sides constant during battery operation, and the energy storage reference value A is set with this in mind.

[0104] Conversely, when the difference between the energy storage capacity of the first battery module 11 and the energy storage capacity of the second battery module 12 is greater than a predetermined energy storage capacity reference value A, the battery management system 70 can perform an operation to consume the energy stored in the first battery module 11. For example, the first battery module 11 can be discharged passively through balancing. Then, after consuming the energy stored in the first battery module 11, the battery management unit 70 repeatedly checks whether the difference between the energy storage capacity of the first battery module 11 and the energy storage capacity of the second battery module 12 equals the predetermined energy storage capacity reference value A. Therefore, the difference between the energy stored in the first battery module 11 and the energy stored in the second battery module 12 eventually becomes approximately equal to the predetermined energy storage capacity reference value A.

[0105] 3. Operation of the battery system according to the present invention in external charging mode

[0106] The external charging mode is an operation that charges the first battery module 11 and the second battery module 12 together by converting the power of the charging unit 60 or the solar cells installed in the vehicle into DC low voltage power through the solar DC-DC converter (SDC) 42, or charges the first battery module 11 and the second battery module 12 separately.

[0107] The vehicle operates separately for charging the battery module from the outside when the vehicle is off and when the vehicle is running (ST mode).

[0108] First, the scenario of charging the battery module from the outside while the engine is off is described. Figure 4 This is a flowchart illustrating the operation of the vehicle battery system according to the present invention in the external charging mode of the vehicle.

[0109] Reference Figure 4 When the vehicle is off, the first relay node N1 of the first relay R1 and the second relay node N2 of the second relay R2 are in a floating state, the third relay R3 is in an open state between the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11, and the sixth relay R6 and the seventh relay R7 are in the initial state (S40) where both ends of each are closed to connect the contact p3 of the first battery module 11 to the ground terminal (GND) and the other contact p4 of the first battery module 11 to the output terminal of the converter 40.

[0110] The battery management system 70 determines whether to perform an operation to charge the first battery module 11 and the second battery module 12 together (hereinafter, for convenience, it is referred to as "module joint charging operation") or to perform an operation to charge the first battery module 11 and the second battery module 12 separately (hereinafter, for convenience, it is referred to as "module individual charging operation") (S41).

[0111] The energy capacity of the first battery module 11 can be used to determine whether to charge the modules together or charge the modules individually in step S41 of the exemplary embodiment of the present invention.

[0112] That is, the battery management system 70 determines whether the energy capacity of the first battery module 11 is equal to or greater than the predetermined charging reference capacity. When the energy capacity of the first battery module 11 is equal to or greater than the charging reference capacity, it means that the energy capacity of the first battery module 11 is sufficient and the first battery module 11 does not need to be charged separately. Therefore, the battery management system 70 performs a module co-charging operation that charges the first battery module 11 and the second battery module 12 together. When the energy capacity of the first battery module 11 is less than the charging reference capacity, it means that the energy capacity of the first battery module 11 is insufficient and the first battery module 11 needs to be charged separately. Therefore, the battery management system 70 performs a module individual charging operation that charges the first battery module 11 and the second battery module 12 separately.

[0113] Accordingly, in step S41, when it is determined that the energy capacity of the first battery module 11 is equal to or greater than the predetermined charging reference capacity and a module shared charging operation is performed, the battery management system 70 connects the first relay node N1 and the first contact a of the first relay R1 to each other, and connects the second relay node N2 and the second contact b of the second relay R2 (S42).

[0114] In this situation, one contact p1 and another contact p2 of the second battery module 12 are connected to the first contact a and the second contact b, respectively, while the two ends of the third relay R3 remain in the open state.

[0115] Next, the battery management system 70 disconnects the two ends of the sixth relay R6 and the seventh relay R7 (S43), and then closes the two ends of the third relay R3 to connect another contact p2 of the second battery module 12 and a contact p3 of the first battery module 11 to each other (S44).

[0116] As described above, if the third relay R3 is closed while the ends of the sixth relay R6 and the seventh relay R7 are closed to each other, insulation breakdown may occur between the low-voltage line of the first battery module 11 and the high-voltage line of the second battery module 12 at the moment the ends of the third relay R3 are closed. Therefore, the ends of the sixth relay R6 and the seventh relay R7 are disconnected, and then the ends of the third relay R3 are closed to each other to prevent insulation breakdown.

[0117] The battery management system 70 applies power from the energy storage unit 80 to the second relay R2 to connect the second relay node N2 of the second relay R2 to the third contact c (S45). Therefore, the power supplied from the first battery module 11 and the second battery module 12 can be applied to the motor control unit 20, and the two ends of the fourth relay R4 and the fifth relay R5 connected to the charging unit 60 are closed (S46) to charge the first battery module 11 and the second battery module 12 using the external power applied through the charging unit 60.

[0118] In step S41, when the battery management system 70 determines that the energy capacity of the first battery module 11 is less than the predetermined charging reference capacity and performs separate charging operations for the first battery module 11 and the second battery module 12, the battery management system 70 connects the first relay node N1 and the first contact a of the first relay R1, connects the second relay node N2 and the second contact b of the second relay R2 (S47), and closes the two ends of the fourth relay R4 and the fifth relay R5 connected to the charging unit 60 (S48). The external power applied by the charging unit 60 is supplied to the second battery module 12 to charge the second battery module 12. The external power applied by the charging unit 60 is supplied to the first battery module 11 through the converter 40 and the sixth relay R6 and the seventh relay R7 whose two ends are closed to charge the first battery module 11.

[0119] Next, the operation of the vehicle battery system according to the present invention for external charging in the vehicle start-up state (ST state) will be described.

[0120] First, the operation of charging the first battery module 11 and the second battery module 12 together while the vehicle is in the start-up state (ST state) will be described.

[0121] Execution is as described above. Figure 2 In steps S1 to S6, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the third contact c, and the two ends of the third relay R3 are closed. Therefore, the other contact p2 of the second battery module 12 and the contact p3 of the first battery module 11 are connected to each other, and the two ends of the sixth relay R6 and the seventh relay R7 are disconnected.

[0122] The battery management system 70 charges the first battery module 11 and the second battery module 12 by closing the two ends of the fourth relay R4 and the fifth relay R5 connected to the charging unit 60 and using the external power applied through the charging unit 60.

[0123] Next, the operation of individually charging the first battery module 11 and the second battery module 12 while the vehicle is in the start-up state (ST state) will be described.

[0124] Execution is as described above. Figure 3A and Figure 3B As described in steps S10 to S14 or steps S20 to S24, when switching from a state where the first battery module 11 and the second battery module 12 are used together to a state where only the second battery module 12 is used alone, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the second contact b, and the two ends of the third relay R3 are disconnected. Therefore, the other contact p2 of the second battery module 12 and one contact p3 of the first battery module 11 are disconnected from each other, and the two ends of the sixth relay R6 and the seventh relay R7 are closed respectively.

[0125] In this state, when the battery management system 70 closes the two ends of the fourth relay R4 and the fifth relay R5 connected to the charging unit 60, the battery management system 70 supplies the external power applied by the charging unit 60 to the second battery module 12 to charge the second battery module 12, and the external power applied by the charging unit 60 is supplied to the first battery module 11 through the converter 40 and the sixth relay R6 and the seventh relay R7 closed at both ends to charge the first battery module 11.

[0126] 4. Operation of the battery system according to the present invention in the flameout switching mode

[0127] The engine shutdown switching mode is the mode that switches the vehicle from driving or external charging mode to engine shutdown mode. Figure 5A This is a flowchart illustrating the operation process of switching from the shared use of the first and second battery modules to the engine shutdown state. Figure 5B This is a flowchart illustrating the process of switching from the standby mode of the second battery module to the engine off mode.

[0128] First, refer to Figure 5A This will describe the operation of switching from the co-use state of the first and second battery modules to the engine off state.

[0129] During vehicle operation or in external charging mode, when the first battery module 11 and the second battery module 12 are used together, steps S1 to S6 as described in the operation of the battery system in startup mode according to the present invention, or steps S40 to S46 in external charging mode, are executed. Therefore, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the third contact c, and the two ends of the third relay R3 are closed. Therefore, the other contact p2 of the second battery module 12 and one contact p3 of the first battery module are connected to each other, and the two ends of the sixth relay R6 and the seventh relay R7 are respectively disconnected (S50).

[0130] Next, the battery management system 70 switches the first relay node N1 of the first relay R1 and the second relay node N2 of the second relay to a floating state, and disconnects both ends of the third relay R3 to disconnect another contact p2 of the second battery module 12 and a contact p3 of the first battery module 11 from each other (S51).

[0131] The reason is that the first battery module 11 needs to provide low-voltage power in the off state. However, when switching to the off state, insulation breakdown may occur between the low-voltage line of the first battery module 11 and the converter 40. Therefore, the nodes N1 and N2 of the first relay R1 and the second relay R2 are switched to the floating state to prevent insulation breakdown, and the two ends of the third relay R3 are disconnected to cut off the low-voltage power supplied through the converter 40.

[0132] Next, in order to provide low-voltage power through converter 40, battery management system 70 provides power from energy storage unit 80 to sixth relay R6 and seventh relay R7 to close the two ends of sixth relay R6 and seventh relay R7 (S52). Therefore, it can switch from the common use state to the shutdown state where low-voltage power is provided by the low-voltage first battery module 11.

[0133] Next, refer to Figure 5B This will describe the operation of switching from the standby state of the second battery module to the off state.

[0134] When the vehicle is in motion and only the second battery module 12 is used, steps S1, S2 and S7 described in the operation of the battery system in the start-up mode according to the present invention are executed. Therefore, the first relay node N1 of the first relay R1 is connected to the first contact a, the second relay node N2 of the second relay R2 is connected to the second contact b, the two ends of the third relay R3 are disconnected, so the other contact p2 of the second battery module 12 and one contact p3 of the first battery module 11 are disconnected, and the two ends of the sixth relay R6 and the seventh relay R7 are closed respectively (S60).

[0135] In this state, in order to provide low-voltage power through converter 40, battery management system 70 switches the first relay node N1 of the first relay R1 and the second relay node N2 of the second relay to a floating state (S61).

[0136] In this situation, the high-voltage power supply to the second battery module 12 stops, the two ends of the third relay R3 are disconnected, and the two ends of the sixth relay R6 and the seventh relay R7 switch to the closed state. Low-voltage power is supplied by the low voltage of the first battery module to switch from the state of using the second battery module alone to the state of being off.

[0137] 5. Operation of the battery system according to the present invention in supplementary charging mode

[0138] Finally, the operation of the battery system according to the present invention in supplemental charging mode will be described.

[0139] The supplementary charging mode is a mode in which, when the vehicle is off and the capacity of the first battery module 11 is equal to or less than a predetermined level, the first battery module 11 is charged by supplying high-voltage power from the second battery module 12 to the converter 40, or by using the solar DC-DC (SDC) converter 42 of the converter 40 to convert the power supplied by the solar cells installed in the vehicle into DC low voltage.

[0140] First, with the vehicle off, steps S50 to S52 described in the engine off switching mode are executed. Therefore, the first relay node N1 of the first relay R1 and the second relay node N2 of the second relay are in a floating state, the two ends of the third relay R3 are open, and the two ends of the sixth relay R6 and the seventh relay R7 are closed to provide low-voltage power by the low-voltage first battery module 11 (S70).

[0141] The battery management system 70 determines whether the energy capacity of the first battery module 11 is equal to or less than a predetermined level (S71).

[0142] In step S71, when the energy capacity of the first battery module 11 is equal to or less than a predetermined level, the battery management system 70 determines that the first battery module 11 needs to be recharged, and connects the first relay node N1 of the first relay R1 to the first contact a, and connects the second relay node N2 of the second relay R2 to the second contact b (S72).

[0143] Then, the high-voltage power applied from the second battery module 12 is supplied to the converter 40 and the low-voltage power is supplied from the converter 40 to the first battery module 11 to supplement the charging of the first battery module 11 (S73). Specifically, the low-voltage power converted by the low-voltage DC-DC converter (LDC) 41 of the converter 40, which converts DC high voltage to DC low voltage, is supplied to the first battery module 11.

[0144] Conversely, when the energy capacity of the first battery module 11 is not equal to or less than the predetermined level in step S71, the first battery module 11 is recharged by the low-voltage power provided by the solar DC-DC converter (SDC) 42 embedded in the converter 40, which converts the power supplied by the solar cell into DC low voltage, without driving the relay (S74).

[0145] at the same time, Figure 7 This is a configuration diagram of a vehicle battery system according to another exemplary embodiment of the present invention. The vehicle battery system shown according to another exemplary embodiment of the present invention is an exemplary embodiment in which only the position of the second relay R2 is changed compared to the foregoing exemplary embodiment, and the operation of the other exemplary embodiment is the same as that of the foregoing exemplary embodiment; therefore, a detailed description of the other exemplary embodiment is omitted.

Claims

1. A vehicle battery system, comprising: A battery assembly, comprising at least one first battery module and at least one second battery module; A first relay, a first relay node electrically connected between a first contact connected to a first point of the second battery module and a second contact connected to a second point of the second battery module, the first relay controlling the connection and disconnection between the first relay node and the first contact, and controlling the connection and disconnection between the first relay node and the second contact; The second relay, the second relay node is electrically connected between the second contact and the third contact connected to the second point of the first battery module. The second relay controls the connection and disconnection between the second relay node and the second contact, and controls the connection and disconnection between the second relay node and the third contact. A third relay is electrically connected between a second point of the second battery module and a first point of the first battery module, and the third relay controls the connection and disconnection between the second point of the second battery module and the first point of the first battery module; The converter is configured to convert the voltage input through the input terminals connected to the first relay node and the second relay node, and to supply the converted voltage to low-voltage electronic components through the output terminal; The sixth relay controls the connection and disconnection between the first point and the ground terminal of the first battery module; The seventh relay controls the connection and disconnection between the second point of the first battery module and the output terminal; The energy storage unit is connected to the output terminal; as well as The battery management system controls the first relay, the second relay, the third relay, the sixth relay, the seventh relay, and the energy storage unit based on the vehicle's driving conditions and the energy storage capacity of the first battery module and the second battery module. The battery management system is configured as follows: Perform start-up mode control from the vehicle's off state until it begins to drive; Determine whether to use both the first battery module and the second battery module or only the second battery module when the vehicle is turned off; When it is determined that both the first battery module and the second battery module are used, the first relay node and the first contact of the first relay are connected, and the second relay node and the second contact of the second relay are connected; Disconnect both ends of the sixth relay and the seventh relay; Close both ends of the third relay to connect the second point of the second battery module and the second point of the first battery module; The power from the energy storage unit is applied to the second relay to connect the second relay's second relay node to the third contact; and The power supplied from the first battery module and the second battery module is applied to the motor control unit.

2. The system according to claim 1, wherein, The first relay node and the second relay node are respectively connected to the input terminal of an inverter or a motor control unit having the inverter, the inverter converting battery power and supplying it to the drive motor.

3. The system according to claim 1, wherein, When it is determined that only the second battery module is used, the battery management system is configured as follows: Connect the first relay node of the first relay to the first contact; Connect the second relay node and the second contact of the second relay; and Only the power from the second battery module is applied to the motor control unit.

4. The system according to claim 1, wherein, When determining whether to use the first battery module and the second battery module, the battery management system is configured as follows: Determine whether the energy capacity of the first battery module is equal to or greater than a predetermined reference capacity; When the energy capacity of the first battery module is equal to or greater than the predetermined reference capacity, both the first battery module and the second battery module are used; and When the energy capacity of the first battery module is less than the predetermined reference capacity, only the second battery module is used.

5. The system according to claim 1, wherein, The battery management system is configured as follows: Control is performed to switch the driving mode from a state of joint use of the first battery module and the second battery module to a state of sole use of the second battery module while the vehicle is in motion; When the first relay node of the first relay is connected to the first contact, it is determined whether it is necessary to switch from the joint use state of the first battery module and the second battery module to the independent use state of the second battery module. When it is determined that it is necessary to switch to the standby mode of the second battery module, the power of the energy storage unit is supplied to the second relay to connect the second relay node and the second contact. Disconnect both ends of the third relay; Close both ends of the sixth relay and the seventh relay; as well as Power from the second battery module is supplied only to the motor control unit, and power from the first battery module is supplied to the low-voltage electronic components to drive them.

6. The system according to claim 1, wherein, The battery management system is configured as follows: Control is performed to switch the driving mode from a state of joint use of the first battery module and the second battery module to a state of sole use of the second battery module while the vehicle is in motion; When the first relay node of the first relay is connected to the first contact, it is determined whether it is necessary to switch from the shared use state of the modules to the individual use state of the second battery module. When it is determined that it is necessary to switch to the standby mode of the second battery module, disconnect the second relay node and the third contact of the second relay and disconnect both ends of the third relay; The six and seven relays are closed by supplying power from the energy storage unit to them. Connect the second relay node and the second contact of the second relay; Power is supplied to the motor control unit only from the second battery module; as well as The power from the first battery module is supplied to the low-voltage electronic components to drive them.

7. The system according to claim 5, wherein, In determining whether it is necessary to switch from the joint use state of the first battery module and the second battery module to the independent use state of the second battery module, When the converter malfunctions or the capacity deviation of the first battery module exceeds the allowable range, it is determined that it is necessary to switch from the shared use state to the individual use state of the second battery module.

8. The system according to claim 1, wherein, The battery management system is configured as follows: Control is performed to switch the driving mode from the standalone use state of the second battery module to the combined use state of the first battery module and the second battery module while the vehicle is in motion; When the first relay node of the first relay is connected to the first contact and the second relay node of the second relay is connected to the second contact, the two ends of the third relay are disconnected and the two ends of the sixth and seventh relays are closed. Determine whether it is necessary to switch from the standby state of the second battery module to the joint state of the modules; When it is determined that it is necessary to switch to the shared use state of the modules, disconnect both ends of the sixth relay and the seventh relay; The second relay node and the third contact are connected by applying power from the energy storage unit to the second relay. The third relay is closed by applying power from the energy storage unit to the third relay. as well as The power supplied from the first battery module and the second battery module is applied to the motor control unit.

9. The system according to claim 8, wherein, In determining whether it is necessary to switch from the standby mode of the second battery module to the shared mode of the modules, When the converter's fault is cleared and the converter is operating normally, or when the energy capacity of the first battery module is balanced and the capacity deviation of the first battery module returns to the allowable range, it is determined that it is necessary to switch to a module co-use state of the first battery module and the second battery module.

10. The system according to claim 1, further comprising: The charging unit is configured to receive power from the outside, convert the received power into power for charging the battery, and provide the converted power. A fourth relay is connected between the charging unit and the second relay node, and the fourth relay controls the connection and disconnection between the charging unit and the second relay node; as well as A fifth relay is connected between the charging unit and the first relay node, and the fifth relay controls the connection and disconnection between the charging unit and the first relay node. The battery management system is configured as follows: Control of an external charging mode in which the first battery module and the second battery module are charged together by the power supplied by the charging unit; When the vehicle is turned off, it is determined whether to perform a joint charging operation for the first battery module and the second battery module or to perform a separate charging operation for the first battery module and the second battery module. When it is determined that a module common charging operation is to be performed to charge the first battery module and the second battery module together, the first relay node of the first relay and the first contact are connected, and the second relay node of the second relay and the second contact are connected. Disconnect the two ends of the sixth and seventh relays, and close the two ends of the third relay to connect the second point of the second battery module to the second point of the first battery module; The power from the energy storage unit is applied to the second relay to connect the second relay's second relay node to the third contact; and The two ends of the fourth and fifth relays are closed to charge the first and second battery modules using the power provided by the charging unit.

11. The system according to claim 10, wherein, When it is determined that an operation to charge the first battery module and the second battery module separately is to be performed, the battery management system is configured as follows: Connect the first relay node of the first relay to the first contact; Connect the second relay node and the second contact of the second relay; Close both ends of the fourth relay and the fifth relay; The second battery module is charged using the power provided by the charging unit; as well as The power provided by the charging unit is supplied from the converter to the first battery module through the sixth and seventh relays to charge the first battery module.

12. The system according to claim 10, wherein, When determining whether to charge all modules together or charge individual modules, the battery management system is configured as follows: Determine whether the energy capacity of the first battery module is equal to or greater than the predetermined charging reference capacity; When it is determined that the energy capacity is equal to or greater than the charging reference capacity, the first battery module and the second battery module are charged together. as well as When it is determined that the energy capacity is less than the charging reference capacity, the first battery module and the second battery module are charged separately.

13. The system according to claim 1, wherein, The battery management system is configured as follows: Control is performed to switch from the co-use state of the first battery module and the second battery module to the engine off state when the vehicle is in motion or charging. When the two ends of the sixth relay and the seventh relay are disconnected respectively, the first relay node of the first relay and the second relay node of the second relay are switched to floating state, and the two ends of the third relay are disconnected. The energy storage unit supplies power to the sixth and seventh relays to close the two ends of the sixth and seventh relays; as well as Switching from the common use state to the shutdown state, where low-voltage power is supplied by the first battery module with low voltage.

14. The system according to claim 1, wherein, The battery management system is configured as follows: Control is performed to switch from the standby state of the second battery module to the engine off state when the vehicle is in motion or charging. When both ends of the third relay are disconnected and the second point of the second battery module and the second point of the first battery module are disconnected, and both ends of the sixth relay and the seventh relay are closed respectively, the first relay node of the first relay and the second relay node of the second relay are switched to floating state; as well as The system switches from the standby state of the second battery module to the off state where the first battery module supplies power.

15. The system according to claim 1, wherein, The converter further includes: Low-voltage DC-DC converters, or LDCs, convert high-voltage DC to low-voltage DC; and A solar-powered DC-DC converter, or SDC, converts the power supplied by installed solar cells into low-voltage DC. The battery management system is configured as follows: When the capacity of the first battery module is equal to or less than a predetermined level when the vehicle is turned off, control is executed to perform a supplementary charging mode to charge the first battery module. The first relay node of the first relay and the second relay node of the second relay are in a floating state, the two ends of the third relay are disconnected, and the two ends of the sixth relay and the seventh relay are closed to supply low-voltage power through the low-voltage first battery module; Determine whether the energy capacity of the first battery module is equal to or less than a predetermined level; When it is determined that the energy capacity of the first battery module is equal to or less than the predetermined level, it is determined that the first battery module needs to be recharged. Connect the first relay node of the first relay to the first contact; Connect the second relay node and the second contact of the second relay; Power is applied from the second battery module via the converter; and Low-voltage power is supplied from the LDC to the first battery module to supplement the charging of the first battery module.

16. The system according to claim 15, wherein, When it is determined that the energy capacity of the first battery module is not equal to or less than the predetermined level, the battery management system supplements the first battery module with low-voltage power supplied by the SDC.

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