Battery pack, electric energy device, and battery pack control method

Abstract

A battery pack, an electric energy device, and a battery pack control method. The battery pack comprises a first battery, a second battery, a first direct current converter, and a battery management system. The battery management system is used for determining parameters of the first battery and the second battery. The first battery and the second battery are connected in series so as to output a high-voltage voltage to the outside. The first battery is connected to the battery management system by means of the first direct current converter so as to supply power to the battery management system. The technical solution of the present disclosure selects one string of batteries from high-voltage batteries composed of the first battery and the second battery as a first battery, and the first battery is connected to the battery management system by means of the first direct current converter. Thus, electric energy is provided for the battery management system by means of the first battery. This solves the problem that when a battery pack is in an offline state such as during transportation or warehousing, parameters of the battery pack cannot be obtained because a battery management system is powered off.

Description

Battery pack, electric energy device and control method of battery pack

[0001] The present disclosure claims priority to the Chinese patent application No. 202410868823.X, filed on June 28, 2024, and entitled "Battery pack, electric energy device and control method of battery pack", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of battery, in particular to a battery pack, an electric energy device and a control method of the battery pack. BACKGROUND

[0003] The battery pack, as the main energy source of the electric energy device, plays a crucial role in the operation of the electric energy device.

[0004] In the related art, the battery management system of the battery pack needs to be connected to an external low-voltage power supply to realize normal work, which also leads to the fact that the battery management system in the battery pack cannot obtain the battery pack parameters such as the battery power change value, the self-discharge data of the battery cell, the storage temperature data and the storage duration in the process of storage or transportation, thereby leaving a safety hazard for the subsequent use of the battery pack. SUMMARY

[0005] The purpose of the present disclosure is to provide a battery pack, an electric energy device and a control method of the battery pack, aiming at solving the problem that the battery pack parameters cannot be obtained in the process of offline transportation in the related art.

[0006] To achieve the purpose of the present disclosure, in a first aspect, the present disclosure provides a battery pack, comprising a first battery, a second battery, a first direct current converter and a battery management system; the battery management system is configured to determine parameters of the first battery and the second battery;

[0007] The first battery and the second battery are connected in series to output a high-voltage voltage; the first battery is connected to the battery management system through the first direct current converter to supply power to the battery management system.

[0008] In a possible implementation, the battery pack further comprises a first power supply interface, a positive electrode of the first battery is connected to a first input end of the first power supply interface through a positive electrode of the first direct current converter and the battery management system.

[0009] A negative electrode of the first battery is connected to a second input end of the first power supply interface through a negative electrode of the first direct current converter.

[0010] In a possible implementation, the battery pack further comprises a second DC converter, and a positive electrode of the second battery is connected to a first input end of the first power interface through a positive electrode of the second DC converter.

[0011] A negative electrode of the first battery is connected to a second input end of the first power interface through a negative electrode of the second DC converter.

[0012] In a possible implementation, the battery pack further comprises a second DC converter, and a positive electrode of the second battery is connected to a negative electrode of the first battery via a positive electrode of the second DC converter and a negative electrode of the first DC converter.

[0013] A negative electrode of the first battery is connected to a positive electrode of the first battery via a negative electrode of the second DC converter and a positive electrode of the first DC converter.

[0014] In a possible implementation, the battery pack further comprises a power distribution unit and a second power interface.

[0015] The second power interface, the second battery, the first battery, and the second DC converter form a current loop through the power distribution unit.

[0016] The power distribution unit is configured to regulate a flow direction of a current among the first battery and the second battery, the second power interface, and the second DC converter.

[0017] In a possible implementation, the power distribution unit comprises a first switch module and a second switch module.

[0018] A first end of the first switch module is connected to the first battery and the second battery, and a second end of the first switch module is connected to a first end of the second switch module and the second DC converter.

[0019] A second end of the second switch module is connected to the second power interface.

[0020] In a possible implementation, the power distribution unit comprises a first switch module and a second switch module.

[0021] A first end of the first switch module is connected to the first battery and the second battery, and a second end of the first switch module is connected to the second power interface.

[0022] A first end of the second switch module is connected to the first battery and the second battery, and a second end of the second switch module is connected to the second DC converter.

[0023] In a possible implementation, the power distribution unit comprises a first switch module and a second switch module.

[0024] The first end of the first switch module is connected with the first battery and the second battery, and the second end of the first switch module is connected with the first end of the second switch module and the second power interface.

[0025] The second end of the second switch module is connected with the second DC converter.

[0026] In a possible implementation, the battery management system comprises a wake-up module configured to generate a wake-up signal for waking up the battery management system in a sleep state.

[0027] In a second aspect, the disclosure further provides a control method applied to a battery pack, the control method comprising the following steps:

[0028] When the battery pack is in an offline state, determining parameters of the battery pack by a battery management system;

[0029] The parameters of the battery pack comprise at least one of the following parameters: a single-cell voltage of each cell of the first battery, a single-cell voltage of each cell of the second battery, a temperature of each cell of the first battery, a temperature of each cell of the second battery, a remaining capacity of each cell of the first battery, and a remaining capacity of each cell of the second battery.

[0030] In a possible implementation, after the step of determining the parameters of the battery pack by the battery management system, the method further comprises the following step:

[0031] Storing the parameters of the battery pack.

[0032] In a possible implementation, after the step of determining the parameters of the battery pack by the battery management system, the method further comprises the following step:

[0033] When the difference between the charge amounts of the first battery and the second battery is greater than a preset charge amount, charging the first battery by the second battery.

[0034] In a possible implementation, the control method further comprises:

[0035] The battery management system enters a sleep state, and in the sleep state, the battery management system stops determining the parameters of the battery pack.

[0036] In a possible implementation, before the step of determining the parameters of the battery pack by the battery management system, the battery management system in the sleep state is woken up.

[0037] In a possible implementation, the step of waking up the battery management system in the sleep state comprises the following steps:

[0038] waking up the battery management system in the sleep state when a circuit formed by the first battery, the first DC converter and the battery management system forms a loop;

[0039] waking up the battery management system in the sleep state when the battery pack is connected to an external wake-up source;

[0040] waking up the battery management system in the sleep state when a duration of the battery management system in the sleep state reaches a preset duration.

[0041] In a possible implementation, the step of waking up the battery management system in the sleep state further comprises the following steps:

[0042] if the battery management system is woken up for N times, N≥2, then at the Nth time of waking up, the self-discharge amount and the self-discharge rate of the battery pack are calculated, and the values of the self-discharge amount and the self-discharge rate are recorded.

[0043] In a possible implementation, before the step of calculating the self-discharge amount and the self-discharge rate of the battery pack, the following steps are further included:

[0044] the values of OCV_N-OCV_N-n and △OCV_set are compared in sequence;

[0045] when OCV_N-OCV_N-n≥△OCV_set exists, the comparison is stopped, and the self-discharge amount and the self-discharge rate of the battery management system at the Nth and the N-nth times of being woken up are calculated;

[0046] if OCV_N-OCV_N-n≥△OCV_set does not exist, the calculation of the self-discharge amount and the self-discharge rate of the battery pack is skipped;

[0047] wherein, OCV_N is the voltage of the battery pack at the Nth time of waking up, OCV_N-n is the voltage of the battery pack at the N-nth time of being woken up, n (1, 2, 3, …, N-1), and △OCV_set is a preset voltage change value of the battery pack.

[0048] In a third aspect, the disclosure further provides an electric energy device, which comprises a load and a battery pack electrically connected to the load, and the battery pack comprises a first battery, a second battery, a first DC converter and a battery management system; the battery management system is configured to determine parameters of the first battery and the second battery.

[0049] The first battery and the second battery are connected in series for outputting high-voltage voltage; the first battery is connected with the battery management system through the first direct-current converter to supply power for the battery management system.

[0050] The technical scheme of the present disclosure selects part of the batteries in the high-voltage battery composed of the first battery and the second battery as the first battery, and connects the first battery and the battery management system through the first direct-current converter. In this way, the first battery provides power for the battery management system. The problem that the battery management system loses power and the parameters of the battery pack cannot be obtained when the battery pack is in an offline state such as transportation or storage is solved. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical scheme in the embodiments of the present disclosure or the prior art, the drawings needed in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0052] Fig. 1 is a structural schematic diagram of one embodiment of the battery pack provided by the present disclosure;

[0053] Fig. 2 is a structural schematic diagram of another embodiment of the battery pack provided by the present disclosure;

[0054] Fig. 3 is a structural schematic diagram of the battery pack in Fig. 1 in an online state;

[0055] Fig. 4 is a structural schematic diagram of a first embodiment of the connection of the first battery, the second battery, the second direct-current converter, the second power interface and the power distribution unit in Fig. 1;

[0056] Fig. 5 is a structural schematic diagram of a second embodiment of the connection of the first battery, the second battery, the second direct-current converter, the second power interface and the power distribution unit in Fig. 1;

[0057] Fig. 6 is a structural schematic diagram of a third embodiment of the connection of the first battery, the second battery, the second direct-current converter, the second power interface and the power distribution unit in Fig. 1;

[0058] Fig. 7 is a flow schematic diagram of a first embodiment of the control method provided by the present disclosure;

[0059] Fig. 8 is a flow schematic diagram of a second embodiment of the control method provided by the present disclosure;

[0060] Fig. 9 is a flow schematic diagram of a third embodiment of the control method provided by the present disclosure;

[0061] Figure 10 is a flowchart illustrating the fourth embodiment of the control method provided in this disclosure;

[0062] Figure 11 is a schematic flowchart of an embodiment of the control method provided in this disclosure for calculating self-discharge quantity and self-discharge rate;

[0063] Figure 12 is a flowchart illustrating another embodiment of the control method provided in this disclosure for calculating self-discharge quantity and self-discharge rate.

[0064] Figure 13 is a simplified logic diagram of the control method provided in this disclosure.

[0065] Explanation of reference numerals in the attached diagram: 100-Battery pack; 1-First battery; 2-Second battery; 3-First DC-DC converter; 4-Battery management system; 5-First power interface; 6-Second DC-DC converter; 7-Power distribution unit; 71-First switch module; 72-Second switch module; 8-Second power interface; 9-Signal interface; 200-High voltage load; 300-Low voltage load. Detailed Implementation

[0066] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0067] It should be noted that when a component is said to be "fixed" to another component, it can be directly on the other component or it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0068] Unless otherwise defined, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the specification of this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used in this disclosure includes any and all combinations of one or more of the associated listed items.

[0069] The following detailed description of some embodiments of this disclosure is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0070] For ease of understanding, the relevant technical terms involved in the embodiments of this disclosure will be explained and described below.

[0071] Offline state: the state of the battery pack when the battery pack is not connected to the load of the electric energy device is referred to as the offline state of the battery pack. For example, the state before the battery pack is assembled into the electric energy device, or the state after the battery pack is detached from the electric energy device, or the state when the battery pack is assembled on the electric energy device but not connected to the load of the electric energy device.

[0072] Online state: the state of the battery pack when the battery pack is connected to the load of the electric energy device is referred to as the online state of the battery pack.

[0073] SOC: the charge amount of the battery pack or the battery cell.

[0074] OCV: the voltage of the battery pack or the battery cell.

[0075] The present disclosure proposes an electric energy device, which can be a vehicle, can be a ship, or can be an aircraft, and the present disclosure does not limit it. For ease of illustration, the vehicle is taken as an example, and when the electric energy device is a vehicle, the vehicle can be an electric vehicle, can be a fuel vehicle, or can be a hybrid vehicle, and the present disclosure does not limit it.

[0076] The vehicle includes a vehicle body, a load, and a battery pack. The vehicle body serves as the support framework of the vehicle and is used to support and connect various parts of the vehicle. The load is provided on the vehicle body, and the load can be an instrument panel, can be an electric motor, or can be a window lifting mechanism, and the present disclosure does not limit it. The battery pack is provided in the battery compartment of the vehicle body, and the battery pack is electrically connected to the load. The battery pack is used to store and deliver electric energy to the outside to maintain the normal use of the load.

[0077] The battery pack includes a battery management system (BMS) for determining parameters of the battery pack, including but not limited to the voltage of the battery pack, which can be the total voltage of the battery pack or the single voltage of each battery cell in the battery pack, the temperature of the battery pack, which can be the total temperature of the battery pack or the single temperature of each battery cell in the battery pack, the remaining electric quantity (SOC) of the battery pack, which can be the total remaining electric quantity of the battery pack or the remaining electric quantity of each battery in the battery pack, and the present disclosure does not limit it.

[0078] During the working process of the battery management system, an external low-voltage power supply is required to supply power to it. Therefore, in the related art, a starting battery is usually provided in the vehicle body, which is used to supply power to the battery management system in the battery pack after the battery pack is connected to the vehicle. This also leads to that when the battery pack is in an offline state, for example, when the battery pack is in a storage or transportation process, the battery management system cannot acquire the parameters of the battery pack in the offline state due to lack of power supply, thereby leaving a safety hazard for the transportation, storage and subsequent use of the battery pack.

[0079] Please refer to FIG. 1 and FIG. 2, to solve the above problems, the battery pack 100 provided by the present disclosure further comprises a first battery 1, a second battery 2 and a first direct current converter 3, the first battery 1 and the second battery 2 are connected in series for outputting high-voltage voltage, and the first battery 1 is connected with the battery management system 4 through the first direct current converter 3 to supply power for the battery management system 4. The technical scheme of the present disclosure selects one of the batteries in the high-voltage battery composed of the first battery 1 and the second battery 2 as the first battery 1, and connects the first battery 1 and the battery management system 4 through the first direct current converter 3. In this way, the first battery 1 provides power for the battery management system 4. The problem that the parameters of the battery pack 100 cannot be acquired when the battery management system 4 loses power in the offline state of the battery pack 100 such as transportation or storage is solved.

[0080] In the following, the battery pack 100 provided by the present disclosure will be described in detail in combination with the drawings.

[0081] The battery pack 100 comprises a battery management system 4 connected with the first battery 1 and the second battery 2 through a signal line to acquire the parameters of the first battery 1 and the second battery 2, which include but are not limited to the temperature of each single battery cell in the first battery 1, the temperature of each single battery cell in the second battery 2, the remaining capacity of each single battery cell in the first battery 1, and the remaining capacity of each single battery cell in the second battery 2. In addition, the battery management system 4 can also control the charging and discharging current of the first battery 1 and the second battery 2.

[0082] The battery pack 100 further comprises a first battery 1 and a first direct current converter 3 (DC / DC), the first battery 1 is composed of a plurality of single battery cells connected in series or in parallel, the first battery 1 is used for outputting voltage, and the voltage of the first battery 1 is VI, 6V≤VI≤60V. The first direct current converter 3 is connected with the first battery 1, and the first direct current converter 3 is used for converting the output voltage of the first battery 1.

[0083] Please refer to FIG. 3, the application scenarios of the first battery 1 and the first direct current converter 3 can be various, when the battery pack 100 is in an offline state, the first battery 1 can be connected with the battery management system 4 through the first direct current converter 3. The first direct current converter 3 can convert the output voltage of the first battery 1 into the working voltage of the battery management system 4, thereby maintaining the normal use of the battery management system 4 in the offline state of the battery pack 100, and solving the problem that the parameters of the battery pack 100 cannot be acquired in the offline state of the battery pack 100.

[0084] When the battery pack 100 is in an online state, the battery pack 100 further comprises a first power interface 5, the first battery 1 can be connected with the first power interface 5 through the first direct current converter 3, and then the first power interface 5 provides power for the low-voltage load 300 in the electric energy equipment, thereby maintaining the normal operation of the low-voltage load 300 in the electric energy equipment.

[0085] Need to be explained, when the electric energy equipment is a vehicle, the above-mentioned low-power low-voltage load 300 can be the instrument panel light of the vehicle, can be the display screen of the vehicle, and can also be the door switch, and the present disclosure does not limit this.

[0086] In an implementable manner of the present disclosure, the positive electrode of the first battery 1 is connected with the first input end of the first power interface 5 through the positive electrode of the first direct current converter 3 and the battery management system 4, and the negative electrode of the first battery 1 is connected with the second input end of the first power interface 5 through the negative electrode of the first direct current converter 3. In this embodiment, the battery management system 4 is connected between the loop formed by the first battery 1 and the first power interface 5, and then the power output from the first battery 1 to the first power interface 5 is controlled by the battery management system 4, so as to avoid excessive discharge of the first battery 1 to the first power interface 5 and damage the service life of the first battery 1.

[0087] The battery pack 100 further comprises a second battery 2, the second battery 2 is formed by a plurality of single batteries in series or in parallel, and the second battery 2 is used to be connected in series with the first battery 1 to form a high-voltage battery, and then output high-voltage voltage to the outside, the high-voltage of the high-voltage battery is V2, 300V≤V2≤1000V. The series connection form of the second battery 2 and the first battery 1 can be various, the second battery 2 can be connected in series with the positive electrode of the first battery, as shown in FIG. 1, the second battery 2 can be connected in series with the positive electrode of the first battery 1, and as shown in FIG. 2, the second battery 2 can be connected with the positive electrode and the negative electrode of the first battery 1 at the same time.

[0088] The second battery 2 is provided, on the one hand, the battery pack 100 further comprises a second direct current converter 6, the positive electrode of the second battery 2 is connected with the first input end of the first power interface 5 through the positive electrode of the second direct current converter 6, and the negative electrode of the first battery 1 is connected with the second input end of the first power interface 5 through the negative electrode of the second direct current converter 6. When the battery is in an online state, the high-voltage current of the second battery 2 and the first battery 1 can be converted by the second direct current converter 6, and then changed into a low-voltage current that can be used by the high-power low-voltage load 300 in the electric energy equipment, and then transmitted to the high-power low-voltage load 300 through the first power interface 5, thereby providing power for the work of the high-power low-voltage load 300.

[0089] It should be noted that when the electric energy equipment is a vehicle, the high-power low-voltage load 300 mentioned above can be a vehicle headlamp, can be an air conditioner blower, and can also be a sunroof or an adjusting mechanism of an electric seat, and the present disclosure does not limit this.

[0090] On the other hand, the battery pack 100 further comprises a second power interface 8, the positive electrode of the second battery 2 is connected to a first input end of the second power interface 8, and the negative electrode of the first battery 1 is connected to a second input end of the second power interface 8. When the battery pack 100 is in an online state, the high-voltage current of the first battery 1 and the second battery 2 can reach the high-voltage load 200 of the electric energy equipment through the second power interface 8, thereby providing electric energy for the operation of the high-voltage load 200.

[0091] It should be noted that when the electric energy equipment is a vehicle, the high-voltage load 200 mentioned above can be a motor, can be a compressor of an air conditioner, and can also be a PTC heater of a vehicle.

[0092] In another aspect, the second battery 2 can also charge the first battery 1, thereby ensuring the consistency of the charges of the first battery 1 and the second battery 2. Specifically, in an implementable manner of the present disclosure, the first DC converter 3 is configured as a bidirectional isolated converter, the positive electrode of the second battery 2 is connected to the negative electrode of the first battery 1 via the positive electrode of the second DC converter 6 and the negative electrode of the first DC converter 3; and the negative electrode of the first battery 1 is connected to the positive electrode of the first battery 1 via the negative electrode of the second DC converter 6 and the positive electrode of the first DC converter 3. In this way, when the battery pack 100 is in an offline state and the current of the first battery 1 is less than a preset electric quantity, the current of the second battery 2 can reach the first battery 1 through the second DC converter 6 and the first DC converter 3, thereby charging the first battery 1. Thus, the consistency of the charges between the first battery 1 and the second battery 2 is ensured, the energy loss caused by the inconsistency of the charges between the first battery 1 and the second battery 2 is reduced, and the stability of the operation of the battery pack 100 is improved.

[0093] The battery pack 100 further comprises a power distribution unit 7, and the second power interface 8 forms a current loop with the second battery 2, the first battery 1 and the second DC converter through the power distribution unit 7. When the first power interface 5 has a working load and the second power interface 8 has no working load, the power distribution unit 7 can control the flow direction of the current between the first battery 1 and the second battery 2, the second power interface 8 and the second DC converter, so as to control the first power interface 5 to be powered and the second power interface 8 to be powered off. In this way, the possibility of current breakdown caused by excessively high voltage at the first input end and the second input end of the second power interface 8 in the idle state of the second power interface 8 is reduced, and the safety of the battery pack 100 is improved. When the first power interface 5 has no working load and the second power interface 8 has a working load, the power distribution unit 7 can also control the current so that the first power interface 5 is powered off and the second power interface 8 is powered on, thereby reducing the energy consumption of the battery pack 100.

[0094] The connection mode of the power distribution unit 7 with the first battery 1, the second battery 2, the second DC converter and the second power interface 8 is various. Please refer to FIG. 4, which is a structural schematic diagram of the first embodiment of the connection of the power distribution unit 7 with the first battery 1, the second battery 2, the second DC converter 6 and the second power interface 8. In the first embodiment, the power distribution unit 7 comprises a first switch module 71 and a second switch module 72. The first end of the first switch module 71 is connected with the first battery 1 and the second battery 2, the second end of the first switch module 71 is connected with the first end of the second switch module 72 and the second DC converter 6, and the second end of the second switch module 72 is connected with the second power interface 8.

[0095] When the first power interface 5 and the second power interface 8 are connected with loads, the power distribution unit 7 can control the first switch module 71 and the second switch module 72 to be closed, the current of the first battery 1 and the second battery 2 can flow to the second DC converter 6 through the first switch module 71, and then flow to the first power interface 5 through the second DC converter 6, so as to supply power to the first power interface 5; the current of the first battery 1 and the second battery 2 can also flow to the second power interface 8 through the first switch module 71 and the second switch module 72, so as to supply power to the second power interface 8.

[0096] When the second power interface 8 is idle, the power distribution unit 7 only needs to disconnect the second switch to stop supplying power to the second power interface 8, so as to reduce the possibility of current breakdown caused by excessively high voltage at the first input end and the second input end of the second power interface 8 in the idle state of the second power interface 8, and improve the safety of the battery pack 100.

[0097] Referring to FIG. 5, FIG. 5 is a structural schematic diagram of a second embodiment in which the power distribution unit 7 is connected with the first battery 1, the second battery 2, the second DC converter 6 and the second power interface 8. In the second embodiment, the power distribution unit 7 comprises a first switch module 71 and a second switch module 72. The first end of the first switch module 71 is connected with the first battery 1 and the second battery 2, and the second end of the first switch module 71 is connected with the first end of the second switch module 72 and the second power interface 8. The second end of the second switch module 72 is connected with the second DC converter 6.

[0098] When the first power interface 5 and the second power interface 8 are connected with loads, the power distribution unit 7 can control the first switch module 71 and the second switch module 72 to be closed, and the current of the first battery 1 and the second battery 2 can flow to the second power interface 8 through the first switch module 71, so as to realize the power supply for the second power interface 8. The current of the first battery 1 and the second battery 2 can also flow to the second DC converter 6 through the first switch module 71 and the second switch module 72, and flow to the first power interface 5 through the second DC converter 6, so as to realize the power supply for the first power interface 5.

[0099] When the first power interface 5 is not connected with a load, the power distribution unit 7 only needs to disconnect the second switch, so as to stop the power supply for the first power interface 5, thereby reducing the energy consumption of the battery pack 100 at the first power interface 5 and prolonging the use time of the battery pack 100.

[0100] Referring to FIG. 6, FIG. 6 is a structural schematic diagram of a third embodiment in which the power distribution unit 7 is connected with the first battery 1, the second battery 2, the second DC converter 6 and the second power interface 8. In the third embodiment, the power distribution unit 7 comprises a first switch module 71 and a second switch module 72. The first end of the first switch module 71 is connected with the first battery 1 and the second battery 2, and the second end of the first switch module 71 is connected with the second power interface 8. The first end of the second switch module 72 is connected with the first battery 1 and the second battery 2, and the second end of the second switch module 72 is connected with the second DC converter 6.

[0101] When the first power interface 5 and the second power interface 8 are connected with loads, the power distribution unit 7 can control the first switch module 71 and the second switch module 72 to be closed, and the current of the first battery 1 and the second battery 2 can flow to the second power interface 8 through the first switch module 71, so as to realize the power supply for the second power interface 8. The current of the first battery 1 and the second battery 2 can also flow to the second DC converter 6 through the second switch module 72, and flow to the first power interface 5 through the second DC converter 6, so as to realize the power supply for the first power interface 5.

[0102] When the second power interface 8 is idle, the power distribution unit 7 disconnects the first switch module 71, and then the power supply to the second power interface 8 can be stopped, thereby reducing the possibility of current breakdown caused by excessively high voltage at the first input end and the second input end of the second power interface 8 in the idle state, and improving the safety of the battery pack 100.

[0103] When the first power interface 5 is idle, the power distribution unit 7 disconnects the second switch module 72, and then the power supply to the first power interface 5 can be stopped, thereby reducing the energy consumption of the battery pack 100 at the first power interface 5 and prolonging the use time of the battery pack 100.

[0104] Compared with the first embodiment and the second embodiment, the present embodiment can realize independent control of the first power interface 5 and the second power interface 8, and more adjustment modes. On the other hand, the parallel connection of the first switch module 71 and the second switch module 72 also makes the second switch module 72 no longer need to bear high-voltage current, and therefore, a switch module with smaller power and lower price can be selected as the second switch module 72 connected between the first battery 1, the second battery 2 and the second DC converter 6, thereby reducing the manufacturing cost of the battery pack 100.

[0105] It should be noted that in each of the above embodiments, the first switch module 71 and the second switch module 72 can be a relay, a contactor or an electronic switch, and the present disclosure does not limit this. Meanwhile, in each of the above embodiments, the power distribution unit 7 can also be provided with active insurance, passive insurance, pre-charge resistance and other electronic devices, which are used in series with the first switch module 71 and the second switch module 72 to protect the circuit safety.

[0106] The battery pack 100 also includes a signal interface 9, a first end of the signal interface 9 being connected with the first power interface 5, and a second end of the signal interface 9 being connected with the second power interface 8. The signal interface 9 is electrically connected with the battery management system 4. The battery management system 4 can transmit the battery parameters of the battery pack 100 to the control system of the vehicle through the signal interface 9, so that the vehicle control system can grasp the working state of the battery pack 100 at any time, thereby performing corresponding control and adjustment to ensure the safe and efficient operation of the battery pack 100.

[0107] The acquisition of the parameters of the battery pack 100 by the battery management system 4 can be continuous real-time acquisition or interval acquisition in time periods, and the present disclosure does not limit this. In an implementable manner of the present disclosure, the battery management system 4 has a hibernation module for controlling the battery management system 4 to hibernate periodically. In the hibernation mode, the battery management system 4 stops collecting the parameters of the battery pack 100, thereby reducing the energy consumption of the battery pack 100. At the same time, in order to ensure that the collection of the parameters of the battery pack 100 can be quickly restored when needed, the battery management system 4 includes a wake-up module for generating a wake-up signal for waking up the battery management system 4 in the hibernation state and enabling the battery management system 4 to continue monitoring and collecting the parameters of the battery pack 100. The design of the hibernation module and the wake-up module ensures that the battery management system 4 can flexibly switch between the hibernation and working states, which can meet the energy-saving demand and also ensure effective monitoring of the state of the battery pack 100 at critical moments. The standby time of the battery pack 100 in the offline state is effectively prolonged.

[0108] Please refer to FIG. 7, the present disclosure also proposes a control method applied to the above-mentioned battery pack, the control method comprising the following steps:

[0109] S101, when the battery pack is in an offline state, determining the parameters of the battery pack by the battery management system; the parameters of the battery pack include at least one of the following parameters: the single-cell voltage of each cell of the first battery, the single-cell voltage of each cell of the second battery, the temperature of each cell of the first battery, the temperature of each cell of the second battery, the remaining capacity of each cell of the first battery, and the remaining capacity of each cell of the second battery.

[0110] In the present embodiment, when the controller of the battery pack judges that the battery pack is in an offline state, the controller will acquire the parameters of the battery pack by the battery management system, so that the operating personnel of the vehicle system or the battery pack can timely master the state change of the battery pack in the offline state, reduce the safety hazards of the battery pack in the subsequent use process, and improve the safety of the use of the battery pack.

[0111] There are various ways for the controller to judge whether the battery pack enters the offline state. The controller can judge whether the battery pack enters the offline state by judging the high-voltage interlock (HVIL) signal in the battery pack. The HVIL signal is mainly used to detect the electrical connection integrity of the high-voltage system in the vehicle, to ensure the safe and reliable connection between high-voltage components such as the battery pack, the motor controller, the direct current converter, etc. When the HVIL signal in the battery pack is in the disconnected state, it proves that the connection between the battery pack and the vehicle is separated, and the controller can make a judgment that the battery pack enters the offline state.

[0112] The controller can also determine whether the battery pack enters the offline state through the vehicle CAN (controller area network) signal. The battery pack mainly communicates with the vehicle through the CAN line and the CAN signal. When the vehicle CAN signal in the battery pack is in a non-communication state, it proves that the connection between the battery pack and the vehicle is disconnected, and the controller can determine that the battery pack enters the offline state.

[0113] To improve the accuracy of the controller in determining the offline state of the battery pack, in an embodiment of the present disclosure, when the battery pack meets the following conditions, it is determined that the battery pack enters the offline state:

[0114] Condition 1: the HVIL signal is in an open state; and

[0115] Condition 2: the battery pack and the vehicle CAN signal are in a non-communication state.

[0116] This embodiment introduces two conditions, "the HVIL signal is in an open state" and "the battery pack and the vehicle CAN signal are in a non-communication state", as the common basis for determining whether the battery pack is in an offline state. In this way, a double-check mechanism is formed between the controller and the battery pack, thereby improving the accuracy of the controller in determining the offline state of the battery pack and facilitating subsequent battery pack parameter reading and recording.

[0117] The power supply of the first battery to the battery management system will cause a difference in charge between the first battery and the second battery. The difference in charge will cause voltage imbalance in the high-voltage battery pack formed by the first battery and the second battery, thereby causing loss of electrical energy of the battery pack.

[0118] To facilitate subsequent device query of the data obtained by the battery management system, after the battery management system obtains the parameters of the battery pack, the method further includes the steps of:

[0119] storing the parameters of the battery pack.

[0120] There are various storage methods for battery pack parameters. In an embodiment of the present disclosure, a non-volatile memory (RAM) is provided in the battery pack. After the battery management system obtains the parameters of the battery pack, the parameters of the battery pack will be stored in the non-volatile memory (RAM). When the electrical energy device is connected to the battery pack, the electrical energy device can read the information in the non-volatile memory (RAM) to obtain the state change of the battery pack in the offline mode, and take appropriate measures (such as charging the battery pack) according to the state change of the battery pack to ensure the safety of the battery pack in the subsequent use process.

[0121] In other embodiments of the present disclosure, after obtaining the parameters of the battery pack, the battery management system can also send the parameters of the battery pack to the cloud through Bluetooth, WIFI or other communication modules for storage. When the electric energy device is connected to the battery pack, the electric energy device can download the parameters of the battery pack from the cloud to obtain the state changes of the battery pack in the offline mode.

[0122] Referring to FIG. 8, to ensure the consistency of the charges of the first battery and the second battery, in an embodiment of the present disclosure, the control method comprises the following steps:

[0123] S201, when the battery pack is in an offline state, determining the parameters of the battery pack by the battery management system.

[0124] S202, when the difference between the charges of the first battery and the second battery is greater than a preset charge amount, charging the first battery by the second battery.

[0125] The preset charge amount is associated with the current charges of the first battery and the second battery, and its value can be obtained by the controller by querying the preset charge amount-first battery and second battery charge amount function pre-stored in the battery pack memory after obtaining the charges of the first battery and the second battery in the current state.

[0126] In the present embodiment, when the battery management system detects the parameters of the battery pack, if the difference between the charges of the first battery and the second battery is greater than the preset charge amount, the controller will control the battery pack to enter the power compensation mode. In the power compensation mode, the switch module arranged between the second battery and the second DC converter will be closed, so that the current of the second battery can pass through the second DC converter, the first DC converter to the first battery, thereby compensating the power of the first battery, improving the consistency of the charges between the first battery and the second battery, balancing the voltage of the battery pack, and reducing the power loss of the battery pack.

[0127] Referring to FIG. 9, the acquisition of the battery pack parameters by the battery management system can be continuous real-time acquisition or interval acquisition in time periods, which is not limited in the present disclosure. To reduce the energy consumption of the battery pack in the offline state, in an embodiment of the present disclosure, the control method comprises the following steps:

[0128] S301, obtaining the parameters of the battery pack by the battery management system.

[0129] The acquisition and storage of the parameters of the battery pack by the battery management system can be performed when the battery pack is in an online state or in an offline state, which is not limited in the present disclosure.

[0130] S302, storing the parameters of the battery pack.

[0131] S303, the battery management system enters the hibernation state, in the hibernation state, the battery management system stops determining the parameters of the battery pack.

[0132] The battery management system can enter the hibernation state in the online state, or in the offline state. When the battery pack is in the offline state, the hibernation command of the battery pack can be issued by the controller of the battery pack. When the battery management system is in the online state, the hibernation command of the battery management system can be issued by the controller of the battery pack or the controller of the power equipment.

[0133] S304, the battery management system in the hibernation state is woken up.

[0134] The battery management system can be woken up in multiple situations. In an embodiment of the present disclosure, a start switch is arranged in the battery pack, which can be a mechanical switch, an electronic switch, or an interlocked PIN switch. Taking the PIN switch as an example, when the start switch is not pressed, the circuits in the battery pack are disconnected when the two interlocked pins are separated from each other. When the start switch is pressed, the circuits in the battery pack are connected to each other when the two interlocked PIN switches are connected to each other, and a loop is formed by the first battery, the first DC converter, and the circuit in which the battery management system is located. When the current of the first battery reaches the battery management system, the battery management system will be woken up, so as to acquire and record the parameters of the battery pack.

[0135] The battery management system can also be woken up by an external wake-up source. The wake-up source can be a parameter detection instrument of the battery pack or a control system of the vehicle, which is not limited in the present disclosure. The wake-up source has a hardware circuit therein, which is connected to the battery pack through a signal line, which can be a CAN line or a hard wire, which is not limited in the present disclosure. When the wake-up source is connected to the battery pack, the hardware circuit in the wake-up source will send a wake-up signal to the battery management system in the battery pack through the signal line connected between the wake-up source and the battery pack, and wake up the battery management system through the wake-up signal. The woken-up battery management system will acquire and record the parameters of the battery pack.

[0136] The battery management system can also be self-woken up. Specifically, a wake-up module is arranged in the battery management system. When the hibernation state of the battery management system reaches a preset time length, the wake-up module will generate a wake-up signal, and wake up the battery management system in the hibernation state through the wake-up signal. The woken-up battery management system will acquire and record the parameters of the battery pack.

[0137] It should be noted that the preset time period is mainly determined by the battery pack power and the duration of the offline mode of the battery pack. When the battery pack has more power or the offline mode lasts for a short time, the preset time period can be set within a shorter time limit. In this way, the collection frequency of the battery management system for the parameters of the battery pack is improved, the accuracy of the battery management system in collecting the parameters of the battery pack for the actual state change of the battery pack is improved, and the safety of the battery pack is improved. When the battery pack has less power or the offline mode lasts for a long time, the preset time period can be set to a longer time limit. In this way, the frequency of waking up the battery management system is reduced, thereby reducing the energy consumption of the battery pack and prolonging the use time of the battery pack in the offline mode.

[0138] S305, when the battery pack is in an offline state, determining the parameters of the battery pack by the battery management system.

[0139] In the embodiment, when the battery management system ends the acquisition of the battery pack, it will enter a sleep state. In the sleep state, the battery management system will stop acquiring information about the battery pack. In this way, the energy consumption of the battery management system for the first battery is reduced. When the controller needs to acquire the parameters of the battery pack by the battery management system, the battery management system in sleep state will be awakened by a wake-up signal, and the acquisition of the parameters of the battery pack will be completed by the battery management system. When the battery management system completes the acquisition of the parameters of the battery pack, the battery management system will continue to enter the sleep state to save the energy consumption of the battery pack and prolong the use time of the battery pack.

[0140] Referring to FIGS. 10 and 11, after being awakened, the battery management system will also calculate the self-discharge amount and the self-discharge rate of the battery pack. Specifically, in an embodiment of the present disclosure, after the step of awakening the battery management system in the sleep state, the following steps are further included:

[0141] S401, if the number of times the battery management system is awakened is N, N≥2, then at the Nth awakening, the self-discharge amount and the self-discharge rate of the battery pack are calculated, and the values of the self-discharge amount and the self-discharge rate are recorded.

[0142] The self-discharge amount of the battery pack and the self-discharge rate of the battery pack can be calculated by the following steps:

[0143] S4011, when the battery pack is woken up for the N-1th time, the open circuit voltage OCV1_N-1 of the battery pack is obtained, and the SOC-OCV function SOC=f(OCV) stored in the memory in advance is queried according to the open circuit voltage OCV1_N-1 to obtain the remaining power SOC_N-1 of the battery pack at the open circuit voltage. When the detection object of the self-discharge amount and the self-discharge rate is the battery cell in the battery pack, OCV1_N-1 can also be the open circuit voltage across the battery cell when the battery pack is woken up for the N-1th time.

[0144] S4012, when the battery pack is woken up for the Nth time, the open circuit voltage OCV1_N of the battery pack is obtained, and the SOC-OCV function SOC=f(OCV) stored in the memory in advance is queried according to the open circuit voltage OCV1_N to obtain the remaining power SOC_N of the battery pack at the open circuit voltage. When the detection object of the self-discharge amount and the self-discharge rate is the battery cell in the battery pack, OCV1_N can also be the open circuit voltage across the battery cell when the battery pack is woken up for the Nth time.

[0145] S4013, according to the relationship formula ΔSOC=SOC_N-SOC_N-1, the change value ΔSOC of the remaining power of the battery pack when the battery pack is woken up for the N-1th and Nth time is calculated. When the detection object of the self-discharge amount and the self-discharge rate is the battery cell in the battery pack, ΔSOC is the change value of the remaining power of the battery cell when the battery pack is woken up for the N-1th and Nth time.

[0146] S4014, according to the relationship formula Q=Q_rate*ΔSOC, the self-discharge amount Q of the battery pack is calculated, wherein Q_rate is the rated capacity of the battery pack at the time of factory shipment. When the detection object of the self-discharge amount and the self-discharge rate is the battery cell in the battery pack, Q_rate is the rated capacity of the battery cell at the time of factory shipment.

[0147] S4015, according to the relationship formula P=Q / △t, the self-discharge rate P of the battery pack is calculated. Wherein, △t is the time interval when the battery pack is woken up for the Nth and N-1th time.

[0148] In this embodiment, when the number of times of waking up of the battery pack is greater than twice, the controller will calculate and record the self-discharge amount and the self-discharge rate of the battery pack according to the open circuit voltage of the battery pack at this time and the open circuit voltage of the battery pack at the last time of waking up of the battery pack. In this way, the control system of the vehicle and the detection personnel of the battery pack can have real-time control of the change of the self-discharge amount of the battery pack, and the safety of the battery pack in the subsequent use process is improved.

[0149] It can be understood that, for the battery pack self-discharge amount and self-discharge rate, the smaller the capacity change of the battery pack, the greater the calculation error of the self-discharge amount and the self-discharge rate of the battery pack. Referring to FIG. 12, in order to improve the comparison of the self-discharge amount and the self-discharge rate of the battery pack, in an embodiment of the present disclosure, the control method further comprises the following steps:

[0150] S501, if the number of times that the battery management system is woken up is N, N≥2, then at the Nth time of waking up, the values of OCV_N-OCV_N-n and △OCV_set are compared in turn.

[0151] S502, when OCV_N-OCV_N-n≥△OCV_set exists, stop comparing, and calculate the self-discharge amount and the self-discharge rate of the battery management system at the Nth and the N-nth times of being woken up.

[0152] S503, if OCV_N-OCV_N-n≥△OCV_set does not exist, skip the calculation of the self-discharge amount and the self-discharge rate of the battery pack.

[0153] Wherein, OCV_N is the voltage of the battery pack at the Nth time of waking up, OCV_N-n is the voltage of the battery pack at the N-nth time of being woken up, n (1, 2, 3…N-1), and △OCV_set is the preset voltage change value of the battery pack.

[0154] In this embodiment, before calculating the self-discharge amount and the self-discharge rate of the battery pack, the controller compares the voltage change amount OCV_N-OCV_N-1 of the battery pack at the current time of waking up and the voltage at the last time of waking up with the preset voltage change value △OCV_set stored in the memory, if OCV_N-OCV_N-1≥△OCV_set, the self-discharge amount and the self-discharge rate of the battery pack between the Nth time of waking up and the N-1th time of waking up are calculated and recorded.

[0155] If OCV_N-OCV_N-1<△OCV_set, the controller compares the voltage at the current time of waking up of the battery pack with the voltage change amount OCV_N-OCV_N-2 at the N-2th time of waking up with the preset voltage change value △OCV_set stored in the memory, if OCV_N-OCV_N-2≥△OCV_set, the self-discharge amount and the self-discharge rate of the battery pack between the Nth time of waking up and the N-2th time of waking up are calculated and recorded.

[0156] If OCV_N-OCV_N-2<△OCV_set, the voltage change amount of the battery pack at the present wakeup and the voltage at the N-3th wakeup is compared with △OCV_set, if OCV_N-OCV_N-3≥△OCV_set, the self-discharge amount and the self-discharge rate of the battery pack between the Nth wakeup and the N-3th wakeup are calculated and recorded. If OCV_N-OCV_N-3<△OCV_set, the voltage change amount of the battery pack at the present wakeup and the voltage at the N-4th wakeup is compared with △OCV_set, and so on.

[0157] If the voltage change amount of the battery pack at the present wakeup and the voltage at the N-N+1th is still less than △OCV_set, the calculation of the self-discharge amount and the self-discharge rate of the battery pack at the present time is skipped. In this way, the capacitance change amount of the battery pack is avoided to be too small, which affects the calculation accuracy of the self-discharge amount and the self-discharge rate of the battery pack.

[0158] It should be noted that in the above calculation formula, △OCV_set is a value pre-set in the memory, which is associated with the voltage OCV of the battery pack. Before calculating the self-discharge amount and the self-discharge rate of the battery pack, the controller will first obtain the current voltage OCV of the battery pack through the battery management system, and query the △OCV_set-OCV function OCV_set=f(OCV) stored in the memory according to the current voltage, and obtain the preset voltage change value of the battery pack at the current voltage according to the OCV_set-OCV function.

[0159] In the following, the control flow of the battery pack provided by the present disclosure will be described in detail in combination with FIG. 13, which includes the following steps:

[0160] S01: press the start switch to make the entire battery pack circuit flow.

[0161] S02: control the first DC converter to enter the first working mode, in which the current of the first battery flows to the battery management system through the first DC converter.

[0162] S03: determine whether the wakeup signal is received, if yes, enter S04.

[0163] S04: wake up the battery management system.

[0164] S05: the battery management system obtains the current of the first battery.

[0165] S06: determine whether the power of the first battery is less than the preset power, if yes, enter S07, if not, enter S11.

[0166] S07: turning on the second DC converter.

[0167] S08: controlling the first DC converter to enter a second working mode, in which the current of the second battery passes through the second DC converter and the first DC converter to reach the first battery, thereby supplementing the first battery with power.

[0168] S09: after the first battery is fully charged, controlling the first DC converter to enter the first working mode. The indicator of the completion of the charging can be that the power of the first battery is greater than a preset power, or that the charging time of the first battery is greater than a preset time length.

[0169] S10: turning off the second DC converter.

[0170] S11: determining whether the battery pack enters an offline mode, if yes, entering step S12, if no, entering S16.

[0171] S12: controlling the battery management system to determine parameters of the battery pack and storing the determined results, the parameters of the battery pack including but not limited to the voltage of the battery pack, which can be the total voltage of the battery pack or the single voltage of each battery cell in the battery pack, the temperature of the battery pack, which can be the total temperature of the battery pack or the single temperature of each battery cell in the battery pack, the residual power of the battery pack, which can be the total residual power of the battery pack or the residual power of each battery in the battery pack.

[0172] S13: setting the wake-up time of the battery management system.

[0173] S14: the battery management system is in sleep.

[0174] S15: determining whether a wake-up signal is received, the wake-up signal can be a wake-up signal sent by a wake-up module in the battery management system after the battery management system reaches a preset sleep time, or a wake-up signal generated by other wake-up sources to the battery management system when the battery pack accesses other wake-up sources, if the wake-up signal is received, entering S04.

[0175] S16: entering an online mode, in which the battery pack supplies power to the load of the power equipment through the first battery or the second battery.

[0176] S17: when the battery pack is in the online mode, determining whether the controller receives a sleep request, if yes, entering S13, if no, returning to S16.

[0177] In the description of the embodiments of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the drawings described in the present disclosure, and are only for the purpose of facilitating the description of the present disclosure and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0178] The above only discloses a preferred embodiment of the present disclosure, and of course cannot limit the scope of the present disclosure. Those skilled in the art can understand that the implementation of all or part of the above-mentioned processes, and the equivalent changes made according to the claims of the present disclosure, still belong to the scope covered by the present disclosure.

Claims

A battery pack (100) includes a first battery (1), a second battery (2), a first DC-DC converter (3), and a battery management system (4); the battery management system (4) is used to determine parameters of the first battery (1) and the second battery (2); The first battery (1) and the second battery (2) are connected in series to output a high voltage; the first battery (1) is connected to the battery management system (4) through the first DC-DC converter (3) to supply power to the battery management system (4). The battery pack as claimed in claim 1, the battery pack (100) further includes a first power interface (5), the positive terminal of the first battery (1) is connected to the first input terminal of the first power interface (5) through the positive terminal of the first DC converter (3) and the battery management system (4); The negative terminal of the first battery (1) is connected to the second input terminal of the first power interface (5) through the negative terminal of the first DC converter (3). The battery pack as claimed in claim 2, the battery pack (100) further includes a second DC-DC converter (6), and the positive terminal of the second battery (2) is connected to the first input terminal of the first power interface (5) through the positive terminal of the second DC-DC converter (6); The negative terminal of the first battery (1) is connected to the second input terminal of the first power interface (5) through the negative terminal of the second DC converter (6). The battery pack (100) as described in any one of claims 1 or 2 further includes a second DC-DC converter (6), wherein the positive terminal of the second battery (2) is connected to the negative terminal of the first battery (1) via the positive terminal of the second DC-DC converter (6) and the negative terminal of the first DC-DC converter (3); The negative terminal of the first battery (1) is connected to the positive terminal of the first battery (1) via the negative terminal of the second DC converter (6) and the positive terminal of the first DC converter (3). The battery pack (100) as described in any one of claims 3 or 4 further includes a power distribution unit (7) and a second power interface (8); The second power interface (8) forms a current loop with the second battery (2), the first battery (1) and the second DC converter (6) through the power distribution unit (7); The power distribution unit (7) is used to regulate the flow of current between the first battery (1) and the second battery (2), the second power interface (8) and the second DC converter (6). The battery pack as claimed in claim 5, wherein the power distribution unit (7) includes a first switch module (71) and a second switch module (72); The first end of the first switch module (71) is connected to the first battery (1) and the second battery (2), and the second end of the first switch module (71) is connected to the first end of the second switch module (72) and the second DC converter (6); The second end of the second switch module (72) is connected to the second power interface (8). The battery pack as claimed in claim 5, wherein the power distribution unit (7) includes a first switch module (71) and a second switch module (72); The first end of the first switch module (71) is connected to the first battery (1) and the second battery (2), and the second end of the first switch module (71) is connected to the second power interface (8); The first end of the second switch module (72) is connected to the first battery (1) and the second battery (2), and the second end of the second switch module (72) is connected to the second DC converter (6). The battery pack as claimed in claim 5, wherein the power distribution unit (7) includes a first switch module (71) and a second switch module (72); The first end of the first switch module (71) is connected to the first battery (1) and the second battery (2), and the second end of the first switch module (71) is connected to the first end of the second switch module (72) and the second power interface (8). The second terminal of the second switch module (72) is connected to the second DC converter (6). The battery pack according to any one of claims 1-8, wherein the battery management system (4) includes a wake-up module for generating a wake-up signal for waking up the battery management system (4) in a dormant state. A control method, applied to a battery pack as described in any one of claims 1 to 9, the control method comprising the following steps: When the battery pack (100) is offline, the parameters of the battery pack (100) are determined by the battery management system (4); The parameters of the battery pack (100) include at least one of the following parameters: the single cell voltage of each cell of the first battery (1), the single cell voltage of each cell of the second battery (2), the temperature of each cell of the first battery (1), the temperature of each cell of the second battery (2), the remaining charge of each cell of the first battery (1), and the remaining charge of each cell of the second battery (2). The control method as described in claim 10, after determining the parameters of the battery pack (100) through the battery management system (4), further includes the step of: The parameters of the battery pack (100) are stored. The control method according to any one of claims 10 or 11, after the step of determining the parameters of the battery pack (100) by the battery management system (4), further includes the following step: When the difference in charge between the first battery (1) and the second battery (2) is greater than a preset charge, the first battery (1) is charged by the second battery (2). The control method according to any one of claims 10-12, further comprising: The battery management system (4) enters a sleep state, during which the battery management system (4) stops determining the parameters of the battery pack (100). The control method as described in claim 13, prior to the step of determining the parameters of the battery pack (100) by the battery management system (4), wakes up the battery management system (4) from its dormant state. The control method as described in claim 14, wherein waking up the battery management system (4) in a dormant state includes the following steps: When the circuit containing the first battery (1), the first DC converter (3) and the battery management system (4) forms a loop, the battery management system (4) in the dormant state is woken up; When the battery pack (100) is connected to an external wake-up source, the battery management system (4) in a dormant state is woken up; When the battery management system (4) has been in a dormant state for a preset period of time, the battery management system (4) in the dormant state is woken up. The control method according to any one of claims 14 or 15, after the step of waking up the battery management system (4) in the dormant state, further includes the following step: If the battery management system (4) is woken up N times, where N≥2, then at the Nth wake-up, the self-discharge amount and self-discharge rate of the battery pack (100) are calculated, and the values ​​of the self-discharge amount and the self-discharge rate are recorded. The control method as described in claim 16, before calculating the self-discharge amount and self-discharge rate of the battery pack (100), further includes the following steps: Compare the values ​​of OCV_N-OCV_N-n with △OCV_set in turn; When there exists OCV_N-OCV_N-n≥△OCV_set, stop the comparison and calculate the self-discharge amount and self-discharge rate of the battery management system (4) when it is woken up for the Nth and Nnth times; If OCV_N-OCV_N-n≥△OCV_set does not exist, then skip the calculation of self-discharge quantity and self-discharge rate of battery pack (100); in, OCV_N is the voltage of the battery pack (100) during the Nth wake-up, OCV_N-n is the voltage of the battery pack (100) during the Nnth wake-up, n (1, 2, 3...N-1), and △OCV_set is the preset voltage change value of the battery pack (100). An electrical power device includes a load and a battery pack (100) electrically connected to the load, wherein the battery pack (100) is a battery pack as described in any one of claims 1 to 9.

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