Multi-branch battery system and electric vehicle

Abstract

The embodiment of the utility model provides a multi-branch battery system and an electric vehicle, and relates to the technical field of battery systems. In the multi-branch battery system, each battery branch is correspondingly provided with a first switch, and the first end of each battery branch is connected to a first connection point; the second end of each battery branch is connected to a second connection point through a first switch; and the second connecting point is connected with the pre-charging load branch or the water cooling loop. According to the multi-branch battery system, the batteries of one or a part of branches with higher voltage can be discharged through the pre-charging load branch or the water cooling loop until the voltage is close to that of other branches, and then the batteries are connected with other branches in parallel to work, so that the circulating current between the branches during parallel work can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of battery systems, and in particular to multi-branch battery systems and electric vehicles. Background Art

[0002] With the development of the new energy industry, more and more vehicles are using lithium batteries as a power source. The electric heavy-duty truck industry has been particularly rapid in recent years. Because trucks operate with heavy loads and long mileages, they require a certain level of battery capacity. Because battery voltage has a certain upper limit, typically below 750V, many manufacturers use multi-branch parallel connections when designing battery systems to increase system capacity.

[0003] Due to differences in battery cell consistency, there is a certain voltage difference between the branches, which will generate a certain circulation current when connected in parallel. The internal resistance of the battery cells in the battery system is relatively low. If the voltage difference between the branches is too large, it will cause a large circulation current. At the same time, in a low temperature environment, the battery cells are usually not allowed to charge. These circulation currents will force the low-voltage battery cells to charge, which will greatly affect the battery cell life and cause a significant decrease in the number of system cycles.

[0004] How to suppress the circulation between branches is the technical problem to be solved by this application. Utility Model Content

[0005] The purpose of the present application is to provide a multi-branch battery system and an electric vehicle to solve the technical problem of how to suppress the circulating current between battery branches in the prior art.

[0006] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0007] In a first aspect, an embodiment of the present application provides a multi-branch battery system, comprising at least two battery branches, each of which is provided with a first switch, and each of which has batteries connected in series;

[0008] The multi-branch battery system further includes a pre-charge load branch or a water cooling circuit;

[0009] The first end of each battery branch is connected to the first connection point;

[0010] The second end of each battery branch is connected to the second connection point via a first switch;

[0011] The second connection point is connected to the pre-charge load branch or the water cooling circuit;

[0012] The first switch is used to connect the batteries of the battery branch corresponding to the first switch to the pre-charge load branch or the water cooling circuit for discharge when closed.

[0013] Optionally, the at least two branches include a first branch and a second branch; each of the first branches is correspondingly provided with a second switch;

[0014] The second end of each of the first branches is connected to the second connection point via a first switch and a second switch;

[0015] The second end of each of the second branches is connected to the second connection point via a first switch;

[0016] The second switch is connected in parallel with the pre-charge load branch.

[0017] Optionally, the pre-charge load branch includes a pre-charge resistor and a loop switch, and the pre-charge resistor and the loop switch are connected in series.

[0018] Optionally, the loop switch includes a first loop switch and a second loop switch; there is only one first-type branch, and the remaining battery branches are the second-type branches;

[0019] The first end of the second switch is connected to the second end of the second switch through the first loop switch, the pre-charging resistor and the second loop switch in sequence.

[0020] Optionally, the multi-branch battery system further includes a pre-charge switch, a discharge switch, a first discharge electrode, and a second discharge electrode; the first discharge electrode is a discharge positive electrode, and the second discharge electrode is a discharge negative electrode, or the first discharge electrode is a discharge negative electrode, and the second discharge electrode is a discharge positive electrode;

[0021] The second connection point is connected to the first end of the pre-charging resistor through the pre-charging switch, and the second end of the pre-charging resistor is connected to the first discharge electrode; the second connection point is connected to the second end of the pre-charging resistor through the discharge switch;

[0022] The first connection point is connected to the second discharge electrode, and a load is connected between the first discharge electrode and the second discharge electrode.

[0023] Optionally, the multi-branch battery system further includes a first charging electrode and a second charging electrode, and one or more charging switches; the first charging electrode is a positive charging electrode and the second discharging electrode is a negative charging electrode, or the first charging electrode is a negative charging electrode and the second discharging electrode is a positive charging electrode;

[0024] The second connection point is connected to the first charging electrode through the charging switch, or the first connection point is connected to the second charging electrode through the charging switch.

[0025] Optionally, the charging switch includes a first charging switch, a second charging switch, a third charging switch and a fourth charging switch; the first charging electrode includes a first charging positive electrode and a second charging positive electrode; the second charging electrode includes a first charging negative electrode and a second charging negative electrode;

[0026] The second connection point is connected to the first charging positive electrode through the first charging switch;

[0027] The second connection point is connected to the second charging positive electrode through the second charging switch;

[0028] The first connection point is connected to the first charging negative electrode through the third charging switch;

[0029] The second connection point is connected to the second negative charging electrode through the fourth charging switch.

[0030] Optionally, the water cooling circuit comprises a compressor.

[0031] Optionally, the water cooling circuit further includes a heater.

[0032] In a second aspect, an embodiment of the present application provides an electric vehicle, comprising the multi-branch battery system of the first aspect.

[0033] Compared with the prior art, this application has the following beneficial effects:

[0034] The multi-branch battery system provided in the embodiment of the present application can enable the batteries of one or a part of the branches with higher voltage to discharge through the pre-charge load branch or the water-cooling circuit, discharge to a state where the voltage is close to that of other branches, and then work in parallel with other branches, which can reduce the circulating current between branches when working in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of a multi-branch battery system provided in an embodiment of the present application;

[0037] Figure 2 A schematic diagram showing a pre-charge load branch or a water cooling circuit with the other end thereof connected to a first connection point via a switch according to an embodiment of the present application;

[0038] Figure 3A schematic diagram of a pre-charge load branch or a water cooling circuit connected in parallel with a second switch provided in an embodiment of the present application;

[0039] Figure 4 A schematic diagram of a pre-charge load branch composed of a pre-charge resistor and a loop switch provided in an embodiment of the present application;

[0040] Figure 5 A schematic diagram of a battery portion including a battery box and a high-voltage control box provided in an embodiment of the present application;

[0041] Figure 6 for Figure 5 An enlarged view of the battery box shown;

[0042] Figure 7 for Figure 5 An enlarged view of the high voltage control box is shown;

[0043] Figure 8 A schematic diagram of a water cooling circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, but not all of the embodiments. Generally, the components of the embodiments of the present application described in the drawings herein can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is claimed, but rather merely represents selected embodiments of the present application. All other embodiments derived by persons of ordinary skill in the art based on the embodiments in this application without creative effort are intended to fall within the scope of protection of this application. The following embodiments and features therein may be combined with each other unless there is a conflict.

[0046] In the description of this application, it should be noted that relational terms such as first and second are used solely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The term "connected" should be understood broadly, for example, it can mean fixed connection, detachable connection, or integral connection; it can be directly connected or indirectly connected through an intermediate medium.

[0047] The embodiments of the present application provide a multi-branch battery system that can be used in electric vehicles such as vehicles to provide power energy for the vehicles.

[0048] like Figure 1 The multi-branch battery system includes at least two battery branches. Each battery branch is provided with a corresponding first switch. Each battery branch has batteries connected in series, such as multiple battery boxes connected in series. The multi-branch battery system also includes a pre-charge load branch or a water cooling circuit. The multi-branch battery system has the following connection relationship:

[0049] The first end of each battery branch is connected to the first connection point P1;

[0050] The second end of each battery branch is connected to the second connection point P2 via a first switch;

[0051] The second connection point P2 is connected to one end of the pre-charge load branch or the water cooling circuit.

[0052] The first connection point P1 and the second connection point P2 are used to connect to the two ends of the load. The first connection point P1 and the second connection point P2 can serve as the two poles of the multi-branch battery system: the first connection point P1 serves as the positive pole of the multi-branch battery system and the second connection point P2 serves as the negative pole of the multi-branch battery system, or the first connection point P1 serves as the negative pole of the multi-branch battery system and the second connection point P2 serves as the positive pole of the multi-branch battery system.

[0053] If there is no first switch and each battery branch is directly connected in parallel, then when the voltage of one battery branch is different from that of another battery branch, the battery branches will charge each other to form a circulating current.

[0054] This solution incorporates a first switch that disconnects the parallel connection between one battery branch and another when their voltages differ. When closed, the first switch connects the corresponding battery branch to the pre-charge load branch or water-cooling circuit for discharge. This allows batteries in one or a portion of a higher-voltage battery branch to be connected to the pre-charge load branch or water-cooling circuit for discharge, discharging to a voltage close to that of the other battery branches, achieving voltage balancing. The battery can then operate in parallel with the other battery branches, effectively reducing circulating currents between the battery branches during parallel operation.

[0055] There are various ways to connect the pre-charge load branch or the water cooling circuit, for example:

[0056] (1) Figure 2 The other end of the pre-charge load branch or the water cooling circuit can be connected to the first connection point P1 through a switch, forming a loop between the first connection point P1 and the second connection point P2 as the positive and negative electrodes, and discharging the battery branch with a higher voltage in this loop;

[0057] (2) Figure 3, wherein one or more battery branches can also be connected in series with a second switch, and the battery branch is connected to the second connection point P2 through a first switch and a second switch, and the other end of the pre-charge load branch or the water cooling circuit is connected to the connection point of the first switch and the second switch, that is, the pre-charge load branch or the water cooling circuit can be connected in parallel with the second switch. Figure 3 Working principle of the circuit.

[0058] Figure 3 In the diagram, from top to bottom, the first battery branch, the second battery branch, and the third battery branch are shown. When the first switch of the first battery branch is closed, the second switch of the first battery branch is open, and the second switch of the second battery branch is closed, the first and second battery branches are in a mutually charging state. Mutual charging means that the battery branch with a higher voltage charges the battery branch with a lower voltage. If the first battery branch has a higher voltage, the first battery branch charges the second battery branch; if the second battery branch has a higher voltage, the second battery branch charges the first battery branch. During mutual charging, the current passes through the pre-charge load branch or the water cooling circuit, which reduces the current during mutual charging.

[0059] like Figure 3 The battery branch is divided into a first branch and a second branch, and each first branch is provided with a second switch. Figure 3 In the example, only the first battery branch is a type 1 branch, while the remaining battery branches are type 2 branches. The second end of each type 1 branch is connected to a second connection point via a first switch and a second switch. The second end of each type 2 branch is connected to a second connection point via a first switch. The second switch is connected in parallel with the pre-charge load branch. Therefore, when the second switch of the type 1 branch is disconnected, the type 1 branch can be connected to one or more other battery branches through the pre-charge load branch to form a mutual charging relationship.

[0060] like Figure 4 The pre-charge load branch may include a pre-charge resistor and a loop switch, and the pre-charge resistor and the loop switch are connected in series.

[0061] Close the first switch corresponding to the first battery branch, close the first switch corresponding to the second battery branch, open the second switch corresponding to the first battery branch, and close the loop switch. Then, the first battery branch and the second battery branch charge each other through the pre-charging resistor, and the first battery branch and the second battery branch achieve a voltage equalization effect.

[0062] Close the first switch corresponding to the first battery branch, close the first switch corresponding to the third battery branch, open the second switch corresponding to the first battery branch, and close the loop switch. Then, the first battery branch and the third battery branch charge each other through the pre-charging resistor, and the first battery branch and the third battery branch achieve a voltage equalization effect.

[0063] After the first battery branch and the second battery branch achieve voltage balancing, and the first battery branch and the third battery branch achieve voltage balancing, the voltage balancing effect of the three battery branches is achieved. Therefore, only one battery branch can be equipped with a corresponding second switch, that is, the battery branch can be used as a medium to balance the voltage of all battery branches.

[0064] The loop switch can cut off the current in the pre-charge load branch and disconnect the electrical connection at least partially on the pre-charge load branch, preventing accidents such as accidental touches. To further disconnect the electrical connection at some locations during the cutoff and prevent accidental touches, a loop switch can be connected in series at both ends of the pre-charge resistor. The loop switch may include a first loop switch and a second loop switch; the first end of the second switch is connected to the second end of the second switch through the first loop switch, the pre-charge resistor, and the second loop switch.

[0065] The pre-charge resistor can be the one connected during power-up by the battery management system. During power-up, the battery management system typically first connects the battery to the load via the pre-charge resistor and then connects the battery to the load without the pre-charge resistor. The pre-charge resistor is reused in the voltage balancing process of this solution.

[0066] The first switch and the second switch mentioned above can be implemented by relays or transistors such as IGBTs.

[0067] Reference below Figure 5 , Figure 5 An embodiment of a multi-branch battery system is presented. Figure 5 On the left is the battery section, and on the right is the high-voltage control box. The battery boxes on the left are connected to the wiring terminals on the high-voltage control box via high-voltage wires. A total of 12 battery boxes are designed, with every four battery boxes forming a battery branch (the number of battery boxes can be different in other embodiments), for a total of three columns, or three battery branches. The second battery box in each column (i.e., battery box 2#, battery box 6#, and battery box 10#) can have an MSD (Manual Service Disconnect) connected in series between the positive and negative poles. When maintenance is required, unplugging the MSD will disconnect the power to the battery branch, avoiding the safety hazards of live maintenance. Figure 6 The enlarged picture of the battery box is shown. In the picture, the upper left corner of each battery box is the positive pole, the lower left corner is the negative pole, the upper right corner is the low voltage input, and the lower right corner is the voltage output. Figure 5The dotted line in the figure shows that the slave low-voltage control harness inside the battery box can be connected to the intranet communication port on the high-voltage control box in a hand-in-hand (daisy chain) manner. To ensure stable communication signals and avoid rebound of tail-end signals, a 120Ω terminal resistor can be designed at the end of the low-voltage output control harness of the 4# battery box.

[0068] The internal structure of the high-voltage control box is divided into two parts, the left side is the positive and negative input, which is mainly connected to the battery box, and the right side is the positive and negative output, which is mainly connected to the load end. There are several relay switches connected in series between the two. These relays can play the role of circuit opening and closing, thereby controlling the voltage output at the output end.

[0069] These circuits are described below. Figure 5 、 Figure 7 , Figure 7 Shown Figure 5 An enlarged view of the high-voltage control box. The positive and negative electrodes in the figure are interchangeable, meaning the positive electrode can be replaced by the negative electrode, and the negative electrode can be replaced by the positive electrode.

[0070] The three terminals on the upper left are connected to three battery branches. Each of the three battery branches is designed with a relay (i.e. the first switch 101 mentioned above) before converging in the high-voltage control box. A relay is also added to the first battery branch as the second switch 102. The converging point is the second connection point. There are five branches designed on the right side of the second connection point, from top to bottom, namely the pre-charge load branch (a relay is designed in the pre-charge load branch as a loop switch 103, and a pre-charge relay 104 pre-charge resistor R1, which is mainly used for the pre-charge function during discharge to prevent the load capacitor from connecting to the circuit under low load state, thereby causing a short circuit in the discharge circuit), the discharge circuit branch (the discharge circuit branch is mainly used to connect to loads such as the motor controller, and a positive discharge relay 105 is connected in series in the middle), the charging circuit branch 1 and the charging circuit branch 2 (the charging circuit branch can be used to connect to the charging socket on the vehicle. Some vehicles use a dual-charger charging method to improve charging efficiency, so two charging circuit branches are designed, connected in series with the first charging relay 106 and the second charging relay 107 respectively), and the water cooling circuit (the water cooling circuit is mainly used to power the water-cooling unit, and the water-cooling unit relay 108 is connected in series in the middle). The bottom area of ​​the high-voltage control box is the negative circuit. On the left are the negative poles of the three branches. The first negative branch is connected in series with a Hall sensor H1 in the middle, and the second negative branch is connected in series with a Hall sensor H2 in the middle. The Hall sensors can monitor the charge and discharge current of the branches. A shunt is designed at the back end of the confluence point (i.e., the first connection point) of the negative branch, mainly for measuring the current in the main line. Due to the limited current acquisition channels of the BMS (Battery Management System), it generally only supports two Hall sensors and one shunt. Therefore, for a three-branch system like the one shown in the figure, Hall sensors can be connected in series in two of the branches. The current of the remaining branch can only be obtained through conversion. There are four branches designed at the right end of the shunt, namely the discharge negative electrode circuit, the first charging negative electrode circuit, the second charging negative electrode circuit, and the water-cooled negative electrode circuit. Except for the water-cooled negative electrode circuit, the other three branches are designed with relays (the first connection point is connected to the first charging negative electrode through the negative electrode discharge relay 109, the first connection point is connected to the first charging negative electrode through the third charging relay 110, and the first connection point is connected to the second charging negative electrode through the fourth charging relay 110), which can ensure that the battery negative electrode is disconnected from the electrode when the power is off.

[0071] Because this solution involves a large number of relays and a limited number of high-side driver interfaces within a single BMS, a multifunctional expansion board can be added to the high-voltage control box. Its primary function is to collect voltages on the three branches and control the relays. Simply adding this multifunctional expansion board can achieve the required functionality, significantly reducing system control complexity and costs.

[0072] Regarding the judgment of relay action and voltage equalization conditions, thresholds can be designed to measure. Thresholds N1 and N2 can be designed: (1) When the pressure difference is less than N1, the pressure difference is small, and the current generated after the branches are connected in parallel is small. It can be quickly consumed by the resistance inside the battery cell. As long as the temperature is above 0°C, the relays on all battery branches can be directly closed, and all battery branches can be directly connected in parallel. (2) If the pressure difference is between N1 and N2, this pressure difference will generate a large current when it is consumed by the resistance of the battery cell itself. In order to reduce this current, the pre-charge resistor in the pre-charge load branch can be used to consume this current. In order to achieve this function, a second switch 102 is added to the first battery branch, and a loop switch 103 is connected in series in the parallel circuit of the second switch 102 and the pre-charge resistor. When the second switch 102 is disconnected and the two loop switches 103 are closed, the pre-charge resistor is connected in series to the first battery branch. At this time, the first switch 101 of the other branches is closed, and the generated circulating current can be consumed by this pre-charge resistor. (3) If the pressure difference between the branches exceeds N2, it is no longer advisable to rely solely on the pre-charge resistor to consume the circulating current. It is necessary to use a larger external load to consume it. Therefore, the load target is turned to the external liquid cooling unit equipment (i.e., water cooling circuit), and its internal load unit (such as Figure 8 ) There can be a compressor refrigeration unit M and a heating unit PTC. These two units can be used to consume the circulating flow and realize the rapid pressure equalization function.

[0073] The following describes an application in a vehicle operating under varying temperature conditions. First, the BMS receives a vehicle power-on command. Each control unit within the battery system performs a self-check and reports any faults. If no faults are detected, the BMS detects the lowest temperature in all battery branches. If the temperature is below 0°C, charging of the battery cells is prohibited below 0°C, and the system switches to heating mode. In some implementations, 0°C can also be set to a different temperature.

[0074] If the temperature is 0°C or above, the system will enter voltage equalization mode. The multi-function expansion board will detect the voltages of all battery branches one by one and compare the values. There are several situations as follows:

[0075] (1) If the pressure difference is ≤ N1, the multifunctional expansion board closes the relays on each branch one by one, and finally sends a message to the BMS indicating that the branch relay closure is completed. The BMS starts the power-on operation based on this message (the power-on operation is to first close the pre-charge relay 104, and then close the discharge relay 105 of the main circuit after the pre-charge is completed, and then disconnect the pre-charge relay 104).

[0076] (2) If the voltage difference is between N1 and N2, the multifunctional expansion board first closes the first switch 101 of the first battery branch, the first switch 101 of the second battery branch, and the two loop switches 103, and then closes the second switch 102 of the first battery branch after an interval of 20ms (in other embodiments, 20ms can be replaced by other time lengths), until the voltage difference between the first battery branch and the second battery branch is less than N3 (N3 can be different from N1 and N2, and N3 can be less than or equal to N1), and then disconnects the first switch 102 of the second battery branch. Switch 101, after an interval of 20ms, close the first switch 101 of the third battery branch. Similarly, when the voltage difference between the first battery branch and the third battery branch is less than N3, disconnect the two loop switches 103, and after an interval of 20ms, close the second switch 102 of the first battery branch. After completing the above actions, the voltage difference between all battery branches can be made less than N1, and the second switch 102 and all the first switches 101 can be closed. The multi-function board sends a branch relay closure completion message to the BMS, and the BMS starts the power-on operation based on this message.

[0077] (3) If the pressure difference exceeds N2, the multifunctional expansion board closes the relay on the battery branch with the largest voltage, and then sends a single branch closed message to the BMS, waiting for the BMS to detect the system temperature. If the temperature is greater than 25°C (in other embodiments, 25°C can be replaced by other temperatures), the BMS sends an auxiliary cooling instruction to the thermal management unit control unit and closes the water cooling unit relay 108. If the temperature is between 0 and 25°C, it sends a heating instruction. After receiving the instruction, the thermal management unit control unit turns on the corresponding load unit. At this time, the multifunctional expansion board continues to monitor the pressure difference until the pressure difference returns to within N1. The multifunctional expansion board sends a message to the BMS. Send a request to stop discharging instruction. After receiving the instruction, BMS sends it to the thermal management unit control unit. The multi-function expansion board then disconnects the relays on all battery branches, and then re-detects the branch voltage after disconnection, and again determines whether the pressure difference is less than N1. If not, the above actions will be repeated until the voltage difference is within N1. The multi-function expansion board then closes the first switch 101 and the second switch 102 of the first battery branch, with an interval of 20ms, and then closes the first switch 101 of the second battery branch. After an interval of 20ms, it closes the first switch 101 of the third battery branch. After completing the above actions, it sends a branch relay closure completion message to the BMS.

[0078] If the temperature is between 0 and -20°C, the system can drive the heating system by discharging the battery branch, thereby increasing its own temperature. First, the multi-function expansion board selects the battery branch with the highest voltage, closes all the relays on the battery branch, and then sends a single branch closed message to the BMS. The BMS sends an auxiliary cooling instruction to the thermal management unit control unit and closes the water cooling unit relay 108. The thermal management unit starts the heating unit PTC until the temperature rises above 5°C (the reason for raising it to 5°C here is mainly to prevent the temperature from dropping below 0°C quickly after heating is stopped. In other implementations, 5°C can be replaced by other temperatures greater than 0°C). The BMS sends a shutdown instruction to the thermal management unit control unit, disconnects the water cooling unit relay 108 after an interval of 20ms, and the multi-function expansion board then disconnects the relay on this battery branch. After completing the above actions, it switches to the pressure equalization mode, that is, one of the above pressure difference ≤ N1, the pressure difference is between N1 and N2, or the pressure difference exceeds N2.

[0079] If the temperature is lower than -20℃, BMS requests to connect to the external charging auxiliary heating power supply. After the connection is completed, BMS closes the positive and negative charging relays, BMS sends an auxiliary cooling instruction to the thermal management unit control unit and closes the water cooling unit relay 108, and the thermal management unit starts the heating unit PTC until the temperature rises above 5℃. BMS sends a shutdown instruction to the thermal management unit control unit, disconnects the water cooling unit relay 108 after an interval of 20ms, BMS disconnects the positive and negative charging relays, and the multi-function expansion board disconnects the relay on this branch. After completing the above actions, it switches to the pressure equalization mode, that is, one of the above pressure difference ≤ N1, the pressure difference is between N1 and N2, or the pressure difference exceeds N2.

[0080] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. Those skilled in the art may understand and implement the present invention without inventive effort.

[0081] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A multi-branch battery system, characterized in that: The device comprises at least two battery branches, each of which is provided with a first switch, and each of which has batteries connected in series; The multi-branch battery system further includes a pre-charge load branch or a water cooling circuit; The first end of each battery branch is connected to the first connection point; The second end of each battery branch is connected to the second connection point via a first switch; The second connection point is connected to the pre-charge load branch or the water cooling circuit; The first switch is used to connect the battery branch corresponding to the first switch to the pre-charge load branch or the water cooling circuit for discharge when closed.

2. The multi-branch battery system according to claim 1, wherein: The at least two battery branches include a first branch and a second branch; each of the first branches is correspondingly provided with a second switch; The second end of each of the first branches is connected to the second connection point via a first switch and a second switch; The second end of each of the second branches is connected to the second connection point via a first switch; The second switch is connected in parallel with the pre-charge load branch.

3. The multi-branch battery system according to claim 2, wherein: The pre-charge load branch includes a pre-charge resistor and a loop switch, and the pre-charge resistor and the loop switch are connected in series.

4. The multi-branch battery system according to claim 3, wherein: The loop switch includes a first loop switch and a second loop switch; there is only one first-type branch, and the remaining battery branches are the second-type branches; The first end of the second switch is connected to the second end of the second switch through the first loop switch, the pre-charging resistor and the second loop switch in sequence.

5. The multi-branch battery system according to claim 3, wherein: The multi-branch battery system further includes a pre-charge switch, a discharge switch, a first discharge electrode and a second discharge electrode; the first discharge electrode is a discharge positive electrode and the second discharge electrode is a discharge negative electrode, or the first discharge electrode is a discharge negative electrode and the second discharge electrode is a discharge positive electrode; The second connection point is connected to the first end of the pre-charging resistor through the pre-charging switch, and the second end of the pre-charging resistor is connected to the first discharge electrode; the second connection point is connected to the second end of the pre-charging resistor through the discharge switch; The first connection point is connected to the second discharge electrode, and a load is connected between the first discharge electrode and the second discharge electrode.

6. The multi-branch battery system according to claim 1, wherein: The multi-branch battery system further includes a first charging electrode and a second charging electrode, and one or more charging switches; the first charging electrode is a positive charging electrode and the second discharging electrode is a negative charging electrode, or the first charging electrode is a negative charging electrode and the second discharging electrode is a positive charging electrode; The second connection point is connected to the first charging electrode through the charging switch, or the first connection point is connected to the second charging electrode through the charging switch.

7. The multi-branch battery system according to claim 6, wherein: The charging switch includes a first charging switch, a second charging switch, a third charging switch and a fourth charging switch; the first charging electrode includes a first charging positive electrode and a second charging positive electrode; the second charging electrode includes a first charging negative electrode and a second charging negative electrode; The second connection point is connected to the first charging positive electrode through the first charging switch; The second connection point is connected to the second charging positive electrode through the second charging switch; The first connection point is connected to the first charging negative electrode through the third charging switch; The second connection point is connected to the second negative charging electrode through the fourth charging switch.

8. The multi-branch battery system according to claim 1, wherein: The water cooling circuit includes a compressor.

9. The multi-branch battery system according to claim 8, wherein: The water cooling circuit also includes a heater.

10. An electric vehicle, characterized in that: The electric vehicle comprises the multi-branch battery system according to any one of claims 1 to 9.

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