Battery pack, battery module and battery control method for electric vehicle

Abstract

The present invention aims to solve the problem that existing battery packs are difficult to handle low-temperature charging; a battery pack, a battery module, and a battery control method for an electric vehicle are provided. The battery pack includes a battery pack, a box body, a management system, a control circuit, and a heating sheet; the battery pack, the management system, the control circuit, and the heating sheet are respectively arranged inside the box body, and a positive output interface, a negative output interface, a charging interface, and a communication connection port are respectively arranged on the box body; the positive output interface and the negative output interface are respectively connected to the positive and negative electrodes of the battery pack; the charging interface is respectively connected to the battery pack and the management system; the communication interface is connected to the management system; the control circuit is respectively connected to the battery pack, the management system, and the heating sheet; the control circuit includes a heating relay, the switch part of the heating relay is connected in series with the heating sheet and arranged between the positive and negative electrodes of the battery pack, and the control part of the heating relay is connected to the management system; during low temperature, heating and charging are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of storage batteries, and particularly to a battery pack, a battery module and a battery control method for an electric vehicle. Background Art

[0002] With the popularity of electric vehicles, the technical field of storage batteries has also developed rapidly. In order to cope with vehicles of different powers, battery packs are selected for combined use, such as the contents shown in the patents with the authorized announcement number CN112151887B and the application publication number CN117439216A. However, in existing battery modules, only the combined performance between different battery packs is considered, while the charging and discharging performance of a single battery pack is ignored. The charging and discharging efficiency of a battery pack is affected by various factors, including but not limited to charging and discharging voltage, ambient temperature, and voltage difference between battery packs. Among them, low ambient temperature will cause the electrolyte in the battery to become viscous or even solidify, directly affecting the activity of the active substances in the electrolyte, increasing the difficulty of ion diffusion, and the diffusion rate of lithium ions in the electrode is slow at low temperature, making it difficult to embed and easy to escape, thus causing a rapid drop in battery capacity and greatly affecting its storage capacity after charging. Therefore, a battery pack, a battery module and a battery control method for an electric vehicle that can adjust the temperature are needed. Summary of the Invention

[0003] The purpose of the present invention is to solve the deficiencies of the prior art and provide a battery pack, a battery module and a battery control method for an electric vehicle.

[0004] To solve the above problems, the present invention adopts the following technical solutions:

[0005] A battery pack for an electric vehicle includes a battery group, and the battery group includes a plurality of batteries connected in series; it also includes a box body, a management system, a control circuit and a heating sheet; wherein the battery group, the management system, the control circuit and the heating sheet are respectively arranged inside the box body, and a positive output interface, a negative output interface, a charging interface and a communication connection port are respectively arranged on the box body; the positive output interface and the negative output interface are respectively connected to the positive and negative electrodes of the battery group; the charging interface is also connected to the battery group and is also connected to the management system; the communication interface is connected to the management system; the control circuit is respectively connected to the battery group, the management system and the heating sheet; the control circuit includes a heating relay, the switch part of the heating relay is connected in series with the heating sheet and is arranged between the positive and negative electrodes of the battery group, and the control part of the heating relay is connected to the management system.

[0006] Further, the management system is a BMS management system. The detection ports of the BMS are respectively connected to the positive and negative electrodes of the battery pack to detect the battery temperature and battery voltage of the battery pack. The control circuit further includes a pre-charge relay, a pre-charge resistor, a main positive relay, and a charging relay. Among them, the switch part of the main positive relay is connected to the positive electrode of the battery pack, and the control part of the main positive relay is connected to the BMS. The switch part of the pre-charge relay and the pre-charge resistor are connected in series and then connected in parallel across both ends of the switch part of the main positive relay. The control part of the pre-charge relay is connected to the BMS. The switch part of the charging relay is connected to the positive electrode of the battery pack, and the control part of the charging relay is connected to the BMS. The end of the charging relay far from the battery pack is also connected to the charging interface provided on the box body. One end of the switch part of the heating relay is connected to the end of the switch part of the charging relay far from the battery pack. The other end of the switch part of the heating relay is connected in series with the heating element and then connected to the negative electrode of the battery pack. The output end of the main positive relay is used as the total positive of the battery and is connected to the positive output interface provided on the box body. The negative electrode of the battery pack is used as the total negative of the battery and is connected to the negative output interface provided on the box body.

[0007] Further, the control circuit further includes a main positive fuse, a charging fuse, a negative fuse, and a pre-charge fuse. Among them, the main positive fuse is connected in series with the switch part of the main positive relay, and one end of the pre-charge relay is arranged between the main positive fuse and the main positive relay. The charging fuse is connected in series with the charging relay. The negative fuse is connected in series between the negative electrode of the battery pack and the negative output interface.

[0008] Further, the BMS is also connected to the box body for detecting the grounding condition of the box body. The BMS is also connected to the total negative of the battery for detecting the insulation condition of the negative electrode of the battery pack. The BMS is also connected to the end of the switch part of the main positive relay far from the battery pack for detecting the pre-charge voltage. The BMS is also connected to the positive electrode of the battery pack for detecting the insulation condition of the positive electrode of the battery pack.

[0009] Further, the control circuit further includes a DC-DC converter for internal power supply, an electric door lock self-locking gear, an electric door lock self-resetting gear, and a power supply relay; the electric door lock self-locking gear and the electric door lock self-resetting gear are switches provided in the electric door lock; the electric door lock self-resetting gear is connected in parallel with the switch part of the power supply relay and then connected in series with the electric door lock self-locking gear; the control part of the power supply relay is connected to the BMS; the positive and negative poles of the input end of the DC-DC converter are respectively connected to the positive and negative poles of the battery pack; the electric door lock self-locking gear and the electric door lock self-resetting gear are arranged between the positive pole of the input end of the DC-DC converter and the positive pole of the battery pack, or between the negative pole of the input end of the DC-DC converter and the negative pole of the battery pack; the output end of the DC-DC converter is connected to the power supply input port of the BMS; the power supply input port of the BMS is also connected to an external normal pressure input interface as an external normal pressure start port; the power supply input port of the BMS is also connected to a charging interface as an external charging start port.

[0010] Further, a DC-DC fuse is also serially arranged between the positive pole of the battery pack and the positive pole of the DC-DC converter.

[0011] Further, the positive pole of the output end of the DC-DC converter is connected to the power supply input port of the BMS after being serially connected with an isolation diode.

[0012] Further, the box body includes a base and a box cover; wherein the base is integrally in the shape of a box with a hollow interior, one end of the base is provided with an opening for placing components, and the side of the base provided with the opening is detachably connected to the box cover; a heating plate is detachably connected to the inner side wall of the base, and a heating sheet is arranged between the heating plate and the inner wall of the base; the battery packs inside the base are arranged in layers, partitions are arranged between the batteries in different layers, and a fence surrounding one week is arranged around the batteries in the same layer; the batteries in different layers are connected in series with each other.

[0013] A battery module for an electric vehicle includes a plurality of the above-mentioned battery packs and also includes a communication line; the battery packs are connected in series with each other through a positive output interface and a negative output interface provided on the battery box; the charging interfaces provided on the box bodies of the battery packs are connected in series with each other; the communication interfaces of each battery pack are respectively connected to the communication line.

[0014] A battery control method for an electric vehicle, based on the above-mentioned battery module, the battery control method includes the following steps:

[0015] Step 1: Wake up the management systems of each battery pack in the battery module, and according to the setting, designate one of the management systems as the main management system and the rest as the secondary management systems; the main management system judges the state of the vehicle, including the charging state and the driving state; if in the charging state, go to Step 2; if in the driving state, go to Step 3;

[0016] Step 2: The main management system enters the driving working state;

[0017] Step 21: The main management system and the secondary management system control the pre-charge relays of the corresponding battery packs to be switched on;

[0018] Step 22: After a set time interval, the main management system and the secondary management system detect the pre-charge voltage and battery voltage of the corresponding battery packs;

[0019] Step 23: The main management system and the secondary management system determine whether the pre-charge voltage reaches the set ratio of the battery voltage; if the pre-charge voltage reaches the set ratio of the battery voltage, then control the main positive relay of the corresponding battery pack to be switched on and send the main positive relay switched-on information to the main management system; otherwise, return to Step 22;

[0020] Step 24: The main management system determines whether the main positive relays of all battery packs have been switched on; if all have been switched on, it means the battery module has been started and the step ends; otherwise, return to Step 22;

[0021] Step 3: The main management system enters the charging working state;

[0022] Step 31: The main management system and the secondary management system control the charging relays of each battery pack to be switched on;

[0023] Step 32: The main management system and the secondary management system detect the temperature of each battery in each battery pack; if the lowest battery temperature t < the set temperature t1, then all battery packs enter the low-temperature charging mode and go to Step 33; otherwise, charge normally and go to Step 34;

[0024] Step 33: The main management system and the secondary management system control the heating relays of all battery packs to be switched on, the heating elements work, and the charging relays are disconnected to enter the pure heating mode; until the set temperature t2 ≤ the lowest battery temperature t < the set temperature t3 is satisfied, then control the heating relays of all battery packs to remain switched on and control the charging relays to be switched on to exit the pure heating mode and enter the charging-while-heating mode; until the lowest battery temperature ≥ the set temperature t3 is satisfied, then disconnect the heating relays of all battery packs and keep the charging relays switched on to exit the charging-while-heating mode and enter the pure charging mode;

[0025] Step 34: The battery module enters the pure charging mode. The main management system and the secondary management system keep the charging relays of all battery packs switched on and detect the battery pack temperature in real time; if the lowest battery temperature t < the set temperature t1, then return to Step 33; otherwise, go to Step 35;

[0026] Step 35: The main management system and the secondary management system detect the voltage of each single battery in the battery packs, and the voltage of the single battery detected by the secondary management system is transmitted to the main management system;

[0027] Step 36: The main management system determines whether the maximum value of the single battery voltage is greater than the set value V1; if the maximum value of the single battery voltage is greater than or equal to the set value V1, the main management system sends a request to pause charging to the external charging device, and sends a request to reduce the charging current after a delay of the set duration until the maximum value of the single battery voltage reaches the set value V2, and then ends the charging; if the maximum value of the single battery voltage is less than the set value V1, continue charging and return to Step 34;

[0028] The methods of waking up the management system in Step 1 include key wake-up and charging gun wake-up. Among them, key wake-up enters the driving state, and charging gun wake-up is in the charging state.

[0029] The beneficial effects of the present invention are:

[0030] By setting a battery pack with a heating plate, cooperating with the management system and the control circuit, controlling the start and stop of the heating plate, ensuring that the battery pack is at an appropriate temperature for charging, ensuring the charging battery capacity, and improving the service life of the battery pack;

[0031] By setting a pre-charge relay and a main positive relay, the battery is pre-charged and discharged first to detect the discharge capacity of the battery pack. After the pre-charge voltage of the battery reaches 90%, the main positive relay is closed to ensure that the battery pack can quickly enter the discharge state after being connected to the external electrical equipment through the main positive relay;

[0032] By setting a charging relay and a heating relay, cooperating with the heating plate, the battery can be switched among the pure heating mode, the charging-while-heating mode, and the pure charging mode, controlling the charging process of the battery pack, and achieving efficient charging in terms of time;

[0033] By setting a power supply relay, cooperating with the main positive relay, when the voltage of the battery pack is too low, the external and internal power supply circuits of the battery pack can be cut off to prevent over-discharge of the battery pack. Description of the Drawings

[0034] Figure 1 It is the overall external shape of a battery pack for Embodiment 1;

[0035] Figure 2 It is the exploded view of the battery pack for Embodiment 1;

[0036] Figure 3 It is another overall external shape of the battery pack for Embodiment 1;

[0037] Figure 4 It is the schematic connection diagram of the battery packs in the battery module for Embodiment 1;

[0038] Figure 5 Schematic diagram of the circuit in the battery pack of Embodiment 1;

[0039] Figure 6 Connection circuit diagram of the management system, battery pack and heating plate in the battery pack of Embodiment 1;

[0040] Figure 7 Schematic diagram of the circuit part for powering the management system in the control circuit of Embodiment 1;

[0041] Figure 8 Schematic diagram of the circuit of the battery module in Embodiment 1;

[0042] Figure 9 For Figure 8 Simplified schematic diagram of the circuit of the battery module;

[0043] Explanation of the drawing reference numerals: Base 1, box cover 2, partition 3, battery 4, armrest 5, management system 6, control circuit 7, positive output interface 8, negative output interface 9, charging interface 10, communication connection port 11. Specific embodiments

[0044] The following illustrates the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0045] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0046] Embodiment 1:

[0047] Such as Figures 1 to 9As shown in the figure, a battery pack for an electric vehicle includes a battery pack. The battery pack includes a number of batteries 4 connected in series; it also includes a box body, a management system 6, a control circuit 7, and a heating sheet. Among them, the battery pack, the management system 6, the control circuit 7, and the heating sheet are respectively arranged inside the box body. The box body is respectively provided with a positive output interface 8, a negative output interface 9, a charging interface 10, and a communication connection port 11. It should be noted that the management system 6 uses an existing BMS management system 6. The BMS management system 6 can detect the voltage and temperature of the battery 4 to prevent the battery 4 from being overcharged or over-discharged. The positive output interface 8 and the negative output interface 9 are respectively connected to the positive and negative electrodes of the battery pack, and are used to directly connect to external electrical equipment or to perform series and parallel connections with different battery packs. The charging interface 10 is also connected to the battery pack, and the charging interface 10 is also connected to the management system 6. On the one hand, the battery pack is charged by an external charging device through the charging interface 10, and on the other hand, the management system 6 is awakened by the external charging device through the charging interface 10. The communication interface is connected to the management system 6. In this example, an 18-23P interface is used. The communication interface is used to enable the management system 6 to transmit the information of the corresponding battery pack to the outside to realize information collection, and to enable the external signal to be transmitted to the management system 6 to control the charging and discharging strategy of the battery pack. The control circuit 7 is respectively connected to the battery pack, the management system 6, and the heating sheet. The control circuit 7 includes a heating relay. The switch part of the heating relay is connected in series with the heating sheet and is arranged between the positive and negative electrodes of the battery pack. The control part of the heating relay is connected to the management system 6, and the management system 6 controls the conduction and cut-off of the switch part of the heating relay.

[0048] The detection ports of the BMS management system 6 are respectively connected to the positive and negative electrodes of the battery pack for detecting the temperature and voltage of the battery 4 in the battery pack; the control circuit 7 further includes a pre-charge relay, a pre-charge resistor, a main positive relay, and a charging relay; wherein the switching part of the main positive relay is connected to the positive electrode of the battery pack, the control part of the main positive relay is connected to the BMS, and the BMS controls the conduction and cut-off of the main positive relay. One end of the main positive relay away from the battery pack is connected to the positive output interface 8 provided on the box body as the total positive of the battery 4; the switching part of the pre-charge relay and the pre-charge resistor are connected in series and then connected in parallel across both ends of the switching part of the main positive relay. The control part of the pre-charge relay is connected to the BMS management system, and the BMS controls the conduction and cut-off of the pre-charge relay; the switching part of the charging relay is connected to the positive electrode of the battery pack, the control part of the charging relay is connected to the BM management system S, and the BMS controls the conduction and cut-off of the charging relay; one end of the charging relay away from the battery pack is further connected to the charging interface 10 provided on the box body to enable an external charging device to charge the battery pack through the charging interface 10; one end of the switching part of the heating relay is connected to the charging interface 10, that is, the end of the switching part of the charging relay away from the battery pack. The other end of the switching part of the heating relay is connected in series with the heating element and then connected to the negative electrode of the battery pack, so that the heating plate connected in series with the heating relay can also work independently when the charging relay is off; the negative electrode of the battery pack is used as the total negative of the battery 4 and is connected to the negative output interface 9 provided on the box body.

[0049] The control circuit 7 further includes a main positive fuse, a charging fuse, a negative fuse, and a pre-charge fuse; wherein the main positive fuse is connected in series with the switching part of the main positive relay, and one end of the pre-charge relay is disposed between the main positive fuse and the main positive relay; the charging fuse is connected in series with the charging relay; the negative fuse is connected in series between the negative electrode of the battery pack and the negative output interface 9.

[0050] The BMS management system is also connected to the box body for detecting the grounding condition of the box body; the BMS management system is also connected to the total negative of the battery 4 for detecting the insulation condition of the negative electrode of the battery pack; the BMS is also connected to the end of the switching part of the main positive relay away from the battery pack for detecting the pre-charge voltage; the BMS is also connected to the positive electrode of the battery pack for detecting the insulation condition of the positive electrode of the battery pack.

[0051] The control circuit 7 further includes a DC-DC converter for internal power supply, an electric lock self-locking gear, an electric lock self-resetting gear, and a power supply relay; the electric lock self-locking gear and the electric lock self-resetting gear are switches provided in the electric lock; the electric lock self-resetting gear is connected in parallel with the switch part of the power supply relay and then connected in series with the electric lock self-locking gear; the control part of the power supply relay is connected to the BMS; the positive and negative poles of the input end of the DC-DC converter are respectively connected to the positive and negative poles of the battery pack; the electric lock self-locking gear and the electric lock self-resetting gear are arranged between the positive pole of the input end of the DC-DC converter and the positive pole of the battery pack, or between the negative pole of the input end of the DC-DC converter and the negative pole of the battery pack. In this example, the input voltage of the DC-DC converter is 36V - 72V; the output end of the DC-DC converter is connected to the power supply input port of the BMS, so that the BMS system can be started by the battery voltage converted by the DC-DC converter. In this example, the voltage output by the output end of the DC-DC converter is 12V. A DC-DC fuse is also connected in series between the positive pole of the battery pack and the positive pole of the DC-DC converter. The positive pole of the output end of the DC-DC converter is connected in series with an isolation diode and then connected to the power supply input port of the BMS. The anode of the isolation diode faces the DC-DC converter, and the cathode of the isolation diode faces the BMS. It should be noted that the electric lock used is an existing electric lock. After inserting the key, the electric lock can be rotated into the electric lock self-locking gear. After entering the electric lock self-locking gear, it can continue to be rotated into the electric lock self-resetting gear. And after releasing the key, the electric lock will return from the electric lock self-resetting gear to the electric lock self-locking gear. After the key is inserted into the electric lock and rotated into the electric lock self-locking gear, the electric lock self-locking gear is turned on. After the key is further rotated into the electric lock self-resetting gear, the electric lock self-resetting gear is turned on. At this time, the input side of the DC-DC converter forms a loop with the battery pack, and the circuit is turned on. Therefore, the output side of the DC-DC converter can output voltage to start the BMS. After the BMS is started, the control part of the power supply relay is first powered on, and then the switch part of the power supply relay is attracted and turned on. At this time, when the key is released, the electric lock rotates back from the electric lock self-resetting gear to the electric lock self-locking gear, causing the electric lock self-resetting gear to turn off, and it can also keep the loop formed between the input end of the DC-DC converter and the battery pack.

[0052] In this example, by setting the power supply relay and cooperating with the electric lock self-resetting gear, it is prevented that during driving, when the main positive relay is turned off by the management system 6 due to the voltage of a single battery 4 in the battery pack being too low, and the electric lock is not turned off, resulting in the BMS management system 6 and the DC-DC converter still consuming electric energy at this time, causing the battery 4 to be over-discharged and damaging the battery 4; therefore, when the voltage of a single battery 4 in the battery pack is too low, the BMS management system 6 will first control the main positive relay to turn off, cut off the power supply of the battery pack to external devices, and then control the power supply relay to turn off, cut off the power supply of the battery pack to internal components, and achieve cutting off all the power consumption circuits of the battery pack.

[0053] The power supply input port of the BMS is also connected to an external normal pressure input interface, serving as an external normal pressure start port; the power supply input port of the BMS is also connected to the charging interface 10, serving as an external charging start port. This means that the BMS system can also be started by the voltage input from the normal pressure input interface and the voltage input from the charging interface 10. In this example, isolation diodes are also provided between the power supply input port of the BMS and the charging interface 10, and between the power supply input port of the BMS and the external normal pressure input interface, ensuring the one-way conduction of current when the isolation diodes do not suffer from reverse breakdown.

[0054] The box body includes a base 1 and a box cover 2; the base 1 is integrally in the shape of a box with a hollow interior, one end of the base 1 is provided with an opening for placing components, and the side of the base 1 where the opening is provided is detachably connected to the box cover 2; a detachable heating plate is provided on the inner side wall of the base 1, and a heating sheet is provided between the heating plate and the inner wall of the base 1; the battery packs inside the base 1 are arranged in layers, a partition 3 is provided between the batteries 4 in different layers, and a fence surrounding one week is provided around the batteries 4 in the same layer; the batteries 4 in different layers are connected in series with each other. In this example, the number of batteries 4 in the lower layer is 8, the number of batteries 4 in the upper layer is 7, a total of 15 batteries 4, and the maximum charging voltage of a single battery 4 is 3.65V, and the maximum charging voltage of the battery pack formed by connecting 15 batteries 4 in series is 54.75V; during implementation, in order to protect the safety of the batteries 4 and prevent overcharging of the batteries 4, the single battery voltage for stopping charging is set to 3.63V, and the total voltage of the battery pack for stopping charging is 54.45V. A handrail 5 for convenient grasping is also provided on the box body, and the handrail 5 can be provided on the base 1 or the box cover 2.

[0055] A battery module for an electric vehicle includes a plurality of the above-mentioned battery packs and also includes communication lines; the battery packs are connected in series with each other through the positive output interface 8 and the negative output interface 9 provided on the box body; the charging interfaces 10 provided on the box bodies of the battery packs are also connected in series with each other, realizing the series connection of each battery pack during charging. After the current enters the battery module from the charging gun, it passes through each battery pack in turn to charge the battery module; the communication interfaces of each battery pack are respectively connected to the communication lines, and the interfaces of the communication lines are matched with the 18 - 23P interfaces; after the box bodies are connected in series with each other through the positive output interface 8 and the negative output interface 9, the different battery packs inside the battery pack are connected in series, and the different heating sheets are connected in series.

[0056] A battery control method for an electric vehicle, based on the above-mentioned battery module, the battery control method includes the following steps:

[0057] Step 1: Wake up the management systems 6 of each battery pack in the battery module, and according to the setting, designate one of the management systems 6 as the main management system, and the remaining management systems 6 as the secondary management systems. In this example, the management system 6 of the first battery pack located at the positive pole in the battery module is designated as the main management system, and the remaining management systems 6 as the secondary management systems; the main management system judges the state of the vehicle, including the charging state and the driving state; if in the charging state, go to Step 2; if in the driving state, go to Step 3;

[0058] Step 2: The main management system enters the driving working state;

[0059] Step 21: The main management system and the secondary management systems control the pre-charge relays of the corresponding battery packs to be switched on;

[0060] Step 22: After a set time interval, the main management system and the secondary management systems detect the pre-charge voltage of the battery pack and the voltage of Battery 4; in this example, it is 3S;

[0061] Step 23: The main management system and the secondary management systems judge whether the pre-charge voltage reaches the set ratio of the voltage of Battery 4. In this example, it is 90%; if the pre-charge voltage reaches the set ratio of the voltage of Battery 4, control the main positive relay of the corresponding battery pack to be switched on and send the main positive relay on information to the main management system; otherwise, return to Step 22;

[0062] Step 24: The main management system judges whether the main positive relays of all battery packs have been switched on; if all have been switched on, it means that the battery module has been started and the step ends; otherwise, return to Step 22;

[0063] Step 3: The main management system enters the charging working state;

[0064] Step 31: The main management system and the secondary management systems control the charging relays of each battery pack to be switched on;

[0065] Step 32: The main management system and the secondary management systems detect the temperature of each Battery 4 in each battery pack; if the lowest Battery 4 temperature t < the set temperature t1, all battery packs enter the low-temperature charging mode and go to Step 33; otherwise, charge normally and go to Step 34; in this example, the set temperature t1 is 0°C;

[0066] Step 33: The main management system and the secondary management system control the heating relays of all battery packs to be switched on and conduct, the heating elements work, and the charging relays are switched off to enter the pure heating mode; until the set temperature t2 ≤ the lowest battery 4 temperature t < the set temperature t3, then control the heating relays of all battery packs to be switched on and conduct, and control the charging relays to be switched on to exit the pure heating mode and enter the heating while charging mode; until the lowest battery 4 temperature ≥ the set temperature t3, then switch off the heating relays of all battery packs and keep the charging relays switched on to exit the heating while charging mode and enter the pure charging mode; in this example, the set temperature t2 is 1 °C and the set temperature t3 is 8 °C;

[0067] Step 34: The battery module enters the pure charging mode. The main management system and the secondary management system keep the charging relays of all battery packs switched on and detect the battery pack temperature in real time; if the lowest battery 4 temperature t < the set temperature t1, then return to Step 33; otherwise, enter Step 35;

[0068] Step 35: The main management system and the secondary management system detect the voltage of individual battery 4 in each battery pack, and the voltage of individual battery 4 detected by the secondary management system is transmitted to the main management system;

[0069] Step 36: The main management system determines whether the maximum value of the voltage of individual battery 4 is greater than the set value V1; if the maximum value of the voltage of individual battery 4 is greater than or equal to the set value V1, then the main management system sends a pause charging request to the external charging device and sends a down - current charging request after a set delay until the maximum value of the voltage of individual battery 4 reaches the set value V2 to end the charging; if the maximum value of the voltage of individual battery 4 is less than the set value V1, then continue charging and return to Step 34; in this example, the set value V1 is 3.6 V and the set value V2 is 3.63 V.

[0070] The methods of waking up the management system 6 in step 1 include key wake-up and charging gun wake-up. Among them, for key wake-up, it enters the driving state. After turning the electric door lock, the BMS and the battery module are connected through the DC-DC converter to achieve power supply wake-up. The key wake-up is obtained by the main management system detecting the state of the electric door lock. When the electric door lock is in the self-locking gear or the self-resetting gear, the electric door lock will send out an ON signal. For charging gun wake-up, it is in the charging state. After connecting an external charging gun, the low-voltage input interface of the charging gun supplies power to the BMS to achieve wake-up. The charging gun wake-up is obtained by detecting the connection state of the external charging gun. When the charging gun is connected to the charging interface 10 of the battery pack, the charging gun will send out a CC signal. It should be noted that the charging gun wake-up has a higher priority, that is, the management system 6 will first detect whether there is a charging gun handshake signal after waking up, and then detect the state of the electric door lock. In addition, in this example, during the charging process of the battery module, if the ON signal is detected, that is, the vehicle starts during charging, the main management system will not only control the charging of the battery pack, but also execute the processes of steps 21 to 24.

[0071] In step 24, after the battery module starts, it will continue to detect the state of the battery pack and the state of the electric door lock. When the ON signal of the electric door lock disappears, or the total voltage of the battery module is lower than the set value, or the voltage of a single battery pack is too low, or the temperature of any battery 4 in the battery pack is too high, the main positive relay of each battery pack will be controlled to disconnect by the main management system and the sub-management system. It should be noted that when the total voltage of the battery module is lower than the set value, or the voltage of a single battery pack is too low, or the temperature of any battery 4 in the battery pack is too high, a fault alarm will also be triggered.

[0072] In step 33, when the battery module enters the low-temperature charging mode, the main management system will request a 5A current from the external charging gun, and the requested voltage is 54.75V. Subsequently, the main management system and the sub-management system will detect the charging current passing through the charging relay of their battery packs. After the charging current is greater than 2A and the duration exceeds 2S, the heating relay corresponding to the battery pack will be energized and turned on, and after 1S, the charging relay will be disconnected to enter the pure heating mode. It should be noted that when the highest battery temperature in the battery pack is higher than 45°C, or the maximum battery temperature difference reaches 25°C, the heating relay corresponding to the battery pack will also be controlled to disconnect.

[0073] In step 34, after entering the spring charging mode, the charging current requested first will be a set value less than 20A and greater than 10A. In this example, the requested charging current is 18A.

[0074] During the implementation process, by setting up a battery pack with a heating plate, in cooperation with the management system 6 and the control circuit 7, the startup and shutdown of the heating plate are controlled to ensure that the battery pack is at an appropriate temperature for charging, guarantee the capacity of the charging battery 4, and extend the service life of the battery pack; by setting up a pre-charge relay and a main positive relay, the battery 4 is first pre-charged and discharged to detect the discharge capacity of the battery pack. After the pre-charge voltage of the battery 4 reaches 90%, the main positive relay is closed to ensure that the battery pack can quickly enter the discharge state after being connected to an external electrical device through the main positive relay; by setting up a charging relay and a heating relay, in cooperation with the heating sheet, the battery 4 can be switched among the pure heating mode, the charging-while-heating mode, and the pure charging mode to control the charging process of the battery pack for efficient charging in terms of time; by setting up a power supply relay, in cooperation with the main positive relay, when the voltage of the battery pack is too low, the external and internal power supply circuits of the battery pack can be cut off to prevent over-discharge of the battery pack.

[0075] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in the field, after understanding the content and principle of the present invention, various modifications and changes in form and details may be made without departing from the principle and structure of the present invention. However, these corrections and changes based on the idea of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A battery pack for an electric vehicle, comprising a battery pack, the battery pack including a plurality of batteries (4) connected in series; characterized in that, It also includes a box body, a management system (6), a control circuit (7), and a heating sheet; wherein the battery pack, the management system (6), the control circuit (7), and the heating sheet are respectively arranged inside the box body, and a positive output interface (8), a negative output interface (9), a charging interface (10), and a communication connection port (11) are respectively arranged on the box body; the positive output interface (8) and the negative output interface (9) are respectively connected to the positive and negative electrodes of the battery pack; the charging interface (10) is also connected to the battery pack, and the charging interface (10) is also connected to the management system (6); the communication interface is connected to the management system (6); the control circuit (7) is respectively connected to the battery pack, the management system (6), and the heating sheet; the control circuit (7) includes a heating relay, and the switch part of the heating relay is connected in series with the heating sheet and arranged between the positive and negative electrodes of the battery pack, and the control part of the heating relay is connected to the management system (6); The management system (6) is a BMS management system (6), and the detection ports of the BMS are respectively connected to the positive and negative electrodes of the battery pack to detect the battery (4) temperature and battery (4) voltage of the battery pack; the control circuit (7) also includes a pre-charge relay, a pre-charge resistor, a main positive relay, and a charging relay; wherein the switch part of the main positive relay is connected to the positive electrode of the battery pack, and the control part of the main positive relay is connected to the BMS; the switch part of the pre-charge relay and the pre-charge resistor are connected in series and then connected in parallel at both ends of the switch part of the main positive relay, and the control part of the pre-charge relay is connected to the BMS; the switch part of the charging relay is connected to the positive electrode of the battery pack, and the control part of the charging relay is connected to the BMS; the end of the charging relay far from the battery pack is also connected to the charging interface (10) arranged on the box body; one end of the switch part of the heating relay is connected to the end of the switch part of the charging relay far from the battery pack, and the other end of the switch part of the heating relay is connected in series with the heating sheet and then connected to the negative electrode of the battery pack; the output end of the main positive relay is used as the total positive of the battery (4) and is connected to the positive output interface (8) arranged on the box body, and the negative electrode of the battery pack is used as the total negative of the battery (4) and is connected to the negative output interface (9) arranged on the box body; The control circuit (7) also includes a main positive fuse, a charging fuse, a negative fuse, and a pre-charge fuse; wherein the main positive fuse is connected in series with the switch part of the main positive relay, and one end of the pre-charge relay is arranged between the main positive fuse and the main positive relay; the charging fuse is connected in series with the charging relay; the negative fuse is connected in series between the negative electrode of the battery pack and the negative output interface (9); The power supply input port of the BMS is also connected to an external normal pressure input interface as an external normal pressure start port; the power supply input port of the BMS is also connected to the charging interface (10) as an external charging start port; The control circuit (7) further includes a DC-DC converter for internal power supply, an electric lock self-locking gear, an electric lock self-resetting gear, and a power supply relay; the electric lock self-locking gear and the electric lock self-resetting gear are switches provided in the electric lock; the electric lock self-resetting gear is connected in parallel with the switch part of the power supply relay and then connected in series with the electric lock self-locking gear; the control part of the power supply relay is connected to the BMS; the positive and negative poles of the input end of the DC-DC converter are respectively connected to the positive and negative poles of the battery pack; the electric lock self-locking gear and the electric lock self-resetting gear are arranged between the positive pole of the input end of the DC-DC converter and the positive pole of the battery pack, or between the negative pole of the input end of the DC-DC converter and the negative pole of the battery pack; the output end of the DC-DC converter is connected to the power supply input port of the BMS.

2. The battery pack of an electric vehicle according to claim 1, characterized in that, The BMS is also connected to the box body for detecting the grounding condition of the box body; the BMS is also connected to the total negative of the battery (4) for detecting the negative pole insulation condition of the battery pack; the BMS is also connected to one end of the switch part of the main positive relay away from the battery pack for detecting the pre-charge voltage; the BMS is also connected to the positive pole of the battery pack for detecting the positive pole insulation condition of the battery pack.

3. The battery pack of an electric vehicle according to claim 1, characterized in that, A DC-DC fuse is also connected in series between the positive pole of the battery pack and the positive pole of the DC-DC converter.

4. The battery pack of an electric vehicle according to claim 1, wherein, The positive pole of the output end of the DC-DC converter is connected in series with an isolation diode and then connected to the power supply input port of the BMS.

5. A battery pack for an electric vehicle according to claim 1, characterized in that, The box body includes a base (1) and a box cover (2); wherein the base (1) is integrally in the shape of a box with a hollow interior, one end of the base (1) is provided with an opening for placing components, and the side of the base (1) provided with the opening is detachably connected to the box cover (2); a heating plate is detachably connected to the inner side wall of the base (1), and a heating sheet is arranged between the heating plate and the inner wall of the base (1); the battery packs inside the base (1) are arranged in layers, a partition (3) is arranged between different layers of batteries (4), and a fence surrounding one week is arranged around the batteries (4) of the same layer; different layers of batteries (4) are connected in series with each other.

6. A battery module for an electric vehicle, characterized in that, It includes a plurality of battery packs as shown in any one of claims 1 to 5, and also includes a communication line; the battery packs are connected in series with each other through a positive output interface (8) and a negative output interface (9) provided on the box body; the charging interfaces (10) provided on the box bodies of the battery packs are connected in series with each other; the communication interfaces of each battery pack are respectively connected to the communication line.

7. A battery control method for an electric vehicle, characterized in that, Based on the battery module according to claim 6, the battery control method includes the following steps: Step 1: Wake up the management systems of each battery pack in the battery module, and according to the setting, designate one of the management systems as the main management system and the remaining management systems as the secondary management systems; the main management system judges the state of the vehicle, including the charging state and the driving state; if it is in the charging state, then go to Step 2; If it is in the driving state, then go to Step 3; Step 2: The main management system enters the driving working state; Step 21: The main management system and the secondary management systems control the pre-charge relays of the corresponding battery packs to be switched on and conduct; Step 22: After a set time interval, the main management system and the secondary management systems detect the pre-charge voltage and the battery voltage of the battery packs corresponding to them; Step 23: The main management system and the secondary management system determine whether the pre-charge voltage reaches the set ratio of the battery voltage. If the pre-charge voltage reaches the set ratio of the battery voltage, control the main positive relay of the corresponding battery pack to be pulled in and conduct, and send the main positive relay conduction information to the main management system. Otherwise, return to Step 22. Step 24: The main management system determines whether the main positive relays of all battery packs have been conducted. If all have been conducted, it means the battery module has been started, and the steps are ended. Otherwise, return to Step 22. Step 3: The main management system enters the charging working state. Step 31: The main management system and the secondary management system control the charging relays of each battery pack to be pulled in and conduct. Step 32: The main management system and the secondary management system detect the temperature of each battery in each battery pack. If the lowest battery temperature t < the set temperature t1, all battery packs enter the low-temperature charging mode and enter Step 33. Otherwise, normal charging is performed and Step 34 is entered. Step 33: The main management system and the secondary management system control the heating relays of all battery packs to be pulled in and conduct, the heating elements work, and the charging relays are disconnected to enter the pure heating mode. Until the set temperature t2 ≤ the lowest battery temperature t < the set temperature t3 is satisfied, control the heating relays of all battery packs to remain pulled in and conduct, and control the charging relays to be pulled in and conduct to exit the pure heating mode and enter the charging while heating mode. Until the lowest battery temperature ≥ the set temperature t3 is satisfied, disconnect the heating relays of all battery packs and keep the charging relays pulled in and conduct to exit the charging while heating mode and enter the pure charging mode. Step 34: The battery module enters the pure charging mode. The main management system and the secondary management system keep the charging relays of all battery packs pulled in and conduct, and detect the battery pack temperature in real time. If the lowest battery temperature t < the set temperature t1, return to Step 33. Otherwise, Step 35 is entered. Step 35: The main management system and the secondary management system detect the voltage of each single battery in each battery pack, and the voltage of each single battery detected by the secondary management system is transmitted to the main management system. Step 36: The main management system determines whether the maximum value of the single battery voltage is greater than the set value V1. If the maximum value of the single battery voltage is greater than or equal to the set value V1, the main management system sends a pause charging request to the external charging device, and sends a current reduction charging request after a set delay until the maximum value of the single battery voltage reaches the set value V2, and the charging ends. If the maximum value of the single battery voltage is less than the set value V1, continue charging and return to Step 34. The methods of waking up the management system in Step 1 include key wake-up and charging gun wake-up. Among them, key wake-up enters the driving state, and charging gun wake-up is in the charging state.

Images