Power battery heating loop and electric automobile

Abstract

The utility model relates to a power battery heating loop and an electric vehicle. The power battery heating loop comprises a relay set, a battery pack, a heating film, a discharging interface and a charging interface. One end of the main positive relay is connected with the positive electrode of the battery pack, the negative electrode of the battery pack is connected with one end of the discharging negative relay, the other end of the discharging negative relay is connected with the negative electrode of the discharging interface, and the positive electrode of the discharging interface is connected with the other end of the main positive relay, one end of the fast charging relay and one end of the heating relay. The other end of the fast charging relay is connected with the anode of the charging interface, the other end of the heating relay is connected with one end of the heating film, and the other end of the heating film is connected with the cathode of the charging interface. According to the invention, the loop between the battery pack and the heating film is disconnected under the low-temperature fast charging and heating working condition, and the loop between the battery pack and the discharging interface is disconnected under the low-temperature discharging and heating working condition, so that the problem of over-charging or over-discharging of the battery cell during low-temperature charging and discharging is solved.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and in particular to a power battery heating circuit and an electric vehicle. Background Technology

[0002] Low-temperature charging systems for power batteries in new energy vehicles are a key technology for new energy vehicles. Taking industrial forklifts as an example, their power battery technology is mostly lithium iron phosphate batteries, and the lithium battery thermal management (BMS) solutions mainly rely on heating film heating and natural cooling. Under the pure heating condition of low-temperature charging, the battery cells need to be heated to 0°C before charging the battery.

[0003] The battery management system (BMS) requests charging current based on the heating film's requirements. Since the requested current and voltage are fixed, but the heating film's resistance is variable and subject to some deviation, there's a possibility that some heating current needs to be output from the battery cell. For cells fed at low temperatures, this poses a risk of cell starvation. Alternatively, if the battery itself lacks charging capability at low temperatures, but the heating current flows back to the cell, it risks cell damage. Therefore, a battery heating circuit is urgently needed to prevent overcharging or over-discharging of the cells during low-temperature charging. Utility Model Content

[0004] Therefore, it is necessary to provide a power battery heating circuit and electric vehicle that can avoid overcharging or over-discharging of battery cells during low-temperature charging, in order to address the above-mentioned technical problems.

[0005] In the first aspect, this embodiment provides a power battery heating circuit, including: a relay group, a battery pack, a heating film, a discharge interface, and a charging interface; the relay group includes: a main positive relay, a fast charging relay, a discharge negative relay, and a heating relay;

[0006] One end of the main positive relay is connected to the positive terminal of the battery pack, the negative terminal of the battery pack is connected to one end of the discharge negative relay, the other end of the discharge negative relay is connected to the negative terminal of the discharge interface, the positive terminal of the discharge interface is connected to the other end of the main positive relay, one end of the fast charging relay, and one end of the heating relay, the other end of the fast charging relay is connected to the positive terminal of the charging interface, the other end of the heating relay is connected to one end of the heating film, and the other end of the heating film is connected to the negative terminal of the charging interface.

[0007] In some embodiments, a main fuse is also included, which is disposed between the battery pack and the main positive relay.

[0008] In some embodiments, a pre-charge circuit in parallel with the main positive relay is also included.

[0009] In some embodiments, the pre-charging circuit includes a pre-charging resistor and a pre-charging relay, with the two ends of the pre-charging resistor connected to one end of the pre-charging relay and one end of the main positive relay, respectively, and the other end of the pre-charging relay connected to the other end of the main positive relay.

[0010] In some embodiments, the device further includes a shunt, one end of which is connected to the negative terminal of the battery pack, and the other end of which is connected to the other end of the heating film.

[0011] In some embodiments, the battery pack also includes a temperature sensor disposed in the battery pack for collecting the temperature status of the battery pack.

[0012] In some embodiments, the battery pack also includes a voltage sensor disposed in the battery pack for acquiring the voltage of the battery pack.

[0013] In some embodiments, the system further includes a battery management system that is connected to the relay group, temperature sensor, voltage sensor, and shunt signal.

[0014] In some embodiments, the battery includes several battery packs, with one end of each battery pack connected to the main positive relay and the other end connected to the discharge negative relay.

[0015] Secondly, this embodiment provides an electric vehicle including the power battery heating circuit described in the first aspect.

[0016] Compared with related technologies, the power battery heating circuit and electric vehicle provided in this embodiment include: a relay group, a battery pack, a heating film, a discharge interface, and a charging interface; the relay group includes: a main positive relay, a fast charging relay, a discharge negative relay, and a heating relay;

[0017] One end of the main positive relay is connected to the positive terminal of the battery pack, and the negative terminal of the battery pack is connected to one end of the discharge negative relay. The other end of the discharge negative relay is connected to the negative terminal of the discharge interface. The positive terminal of the discharge interface is connected to the other end of the main positive relay, one end of the fast charging relay, and one end of the heating relay. The other end of the fast charging relay is connected to the positive terminal of the charging interface. The other end of the heating relay is connected to one end of the heating film, and the other end of the heating film is connected to the negative terminal of the charging interface. Through this embodiment, closing the fast charging relay and the heating relay under low-temperature fast charging and heating conditions can disconnect the circuit between the battery pack and the heating film, preventing over-discharge and over-charging of the battery pack cells. Similarly, closing the main positive relay and the heating relay under low-temperature discharge and heating conditions can disconnect the circuit between the battery pack and the discharge interface, preventing over-discharge of the battery pack cells. This solves the problem of overcharging or over-discharging of battery cells during low-temperature charging and discharging.

[0018] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 This is a circuit diagram of the power battery heating circuit in one embodiment;

[0021] Figure 2 This is a circuit diagram of the power battery heating circuit in another embodiment.

[0022] In the diagram: 1. Relay group; 11. Main positive relay; 12. Fast charging relay; 13. Discharge negative relay; 14. Heating relay; 2. Battery pack; 3. Heating film; 4. Discharge interface; 5. Charging interface; 6. Main fuse; 7. Pre-charge circuit; 71. Pre-charge resistor; 72. Pre-charge relay; 8. Shunt. Detailed Implementation

[0023] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.

[0025] Low-temperature charging systems for power batteries in new energy vehicles are a key technology for new energy vehicles. Taking industrial forklifts as an example, their power battery technology is mostly lithium iron phosphate batteries, and the lithium battery thermal management (BMS) solutions mainly rely on heating film heating and natural cooling. Under the pure heating condition of low-temperature charging, the battery cells need to be heated to 0°C before charging the battery.

[0026] In the existing technology, a branch line is split off after the main fuse, which is connected in sequence to the heating positive relay, the heating film, the heating negative relay and the main negative relay. In the pure charging heating state, the fast charging relay, the heating positive relay, the heating negative relay and the main negative relay are closed to heat the heating film. During heating, the four relays on the charging heating circuit need to be closed to heat the battery.

[0027] The BMS requests charging current based on the heating film's requirements. While the requested current and voltage are fixed, the resistance of the heating film is variable and subject to some deviation. If the heating film's resistance is too low, the actual current consumed by the heating film exceeds the requested current, and the remaining current must be supplied by the battery itself. In this case, some heating current may need to be output from the battery cell. In low-temperature environments, when the battery is in a discharged state, the battery cell voltage drops to an unsafe level before it has been heated to a rechargeable temperature, affecting cell lifespan. If the heating film's resistance is too high, the actual current consumed by the heating film is less than the requested current, and the remaining current flows to the battery. In low-temperature environments, the battery itself lacks charging capability, but the backflow of current into the cell can damage it. Therefore, the heating circuit in existing technology may experience overcharging or over-discharging of the battery cell during low-temperature charging.

[0028] This embodiment provides a power battery heating circuit. Figure 1 This is a circuit diagram of the power battery heating circuit in this embodiment, as shown below. Figure 1 As shown, the circuit includes:

[0029] The relay group 1 (not shown in the figure), battery pack 2, heating film 3, discharge interface 4, and charging interface 5; the relay group 1 includes: main positive relay 11, fast charging relay 12, discharge negative relay 13, and heating relay 14;

[0030] One end of the main positive relay 11 is connected to the positive terminal of the battery pack 2, the negative terminal of the battery pack 2 is connected to one end of the discharge negative relay 13, the other end of the discharge negative relay 13 is connected to the negative terminal of the discharge interface 4, the positive terminal of the discharge interface 4 is connected to the other end of the main positive relay 11, one end of the fast charging relay 12, and one end of the heating relay 14, the other end of the fast charging relay 12 is connected to the positive terminal of the charging interface 5, the other end of the heating relay 14 is connected to one end of the heating film 3, and the other end of the heating film 3 is connected to the negative terminal of the charging interface 5.

[0031] Among them, the positive terminal of the discharge interface 4 is connected to a main positive relay 11, and the negative terminal is connected to a discharge negative relay 13. The positive terminal of the charging interface 5 has a main positive relay 11 and a fast charging relay 12, and the negative terminal has no relay. One end of the heating relay 14 is connected between the fast charging relay 12 and the main positive relay 11, and the other end is connected to the front end of the discharge negative relay 13. There is no heating negative relay.

[0032] During low-temperature fast charging heating, the fast charging relay 12 and the heating relay 14 are closed first. At this time, since the main positive relay 11 is not closed, the circuit between the battery pack 2 and the heating film 3 is in an open state. The charging current of the heating film 3 is entirely provided by the charger (charging pile, charging equipment, etc.) through the charging interface 5. There is no situation where the battery pack 2 needs to provide current to the heating film 3, or where excess current from the heating film 3 flows to the battery pack 2. A fast charging circuit is formed between the positive terminal of the charging interface 5, the fast charging relay 12, the heating relay 14, the heating film 3, and the negative terminal of the charging interface 5. The heating relay 14 and the heating film 3 form a heating circuit. When the heating relay 14 is closed, the battery pack 2 is heated through the heating film 3. Once the battery cells of the battery pack 2 are heated to a rechargeable temperature, the main positive relay 11 is closed to connect the battery pack 2 to the fast charging circuit for charging. The heating film 3 can be made of a heating material, such as metal alloys (e.g., nickel-chromium alloys), carbon nanotubes, graphene, etc. When current passes through the heating material, the heating film 3 generates heat, which is then transferred to the battery pack 2 through thermal conduction. Specifically, it can be tightly attached to the surface of the battery cell in the battery pack 2. This tight attachment ensures that the heat generated by the heating film 3 can be efficiently transferred to the battery pack 2, quickly raising the temperature of the battery cell.

[0033] During low-temperature discharge heating, the main positive relay 11 and the heating relay 14 are closed first. At this time, since the discharge negative relay 13 is not closed, the circuit between the battery pack 2 and the discharge interface 4 is in an open state, and the battery pack 2 is heated through the heating film 3. A discharge heating circuit is formed between the positive terminal of the battery pack 2, the main positive relay 11, the heating relay 14, the heating film 3, and the negative terminal of the battery pack 2. When the heating relay 14 is closed, the battery pack 2 is heated through the heating film 3. After the battery cells of the battery pack 2 are heated to the discharge temperature, the discharge negative relay 13 is closed, and power is supplied to the external vehicle through the discharge interface 4.

[0034] Through the above steps, closing the fast charging relay 12 and the heating relay 14 under low-temperature fast charging heating conditions disconnects the circuit between the battery pack 2 and the heating film 3. The charging current for the heating film 3 is entirely provided by the charger (charging pile, charging equipment, etc.) through the charging interface 5. There is no need for the battery pack 2 to provide current to the heating film 3, nor is there any excess current from the heating film 3 flowing to the battery pack 2, thus preventing over-discharge and over-charging of the battery pack 2 cells. Under low-temperature discharge heating conditions, closing the main positive relay 11 and the heating relay 14 disconnects the circuit between the battery pack 2 and the discharge interface 4, preventing over-discharge of the battery pack 2 cells. Once the battery pack 2 cells are heated to a rechargeable or dischargeable temperature, the battery pack 2 is then charged or discharged. This not only solves the problem of overcharging or over-discharging cells during low-temperature charging but also prevents over-discharge during low-temperature discharge, better protecting the cells and extending battery life. Furthermore, this solution only requires one discharge negative relay, eliminating the need for a heating negative relay, further saving costs.

[0035] In some of these embodiments, such as Figure 1 As shown, the power battery heating circuit also includes:

[0036] The main fuse 6 is located between the battery pack 2 and the main positive relay 11.

[0037] The main fuse 6 is used for overload protection of the battery pack 2. When a fault or abnormality occurs in the circuit of the battery pack 2, the current continuously increases, which may damage some important components in the circuit, burn out the circuit, or even cause a fire. Therefore, by installing the main fuse 6 in the circuit between the battery pack 2 and the main positive relay 11, the main fuse 6 will melt and cut off the current when the current abnormally rises to a certain level and temperature, thereby protecting the safe operation of the circuit.

[0038] In some of these embodiments, such as Figure 1 As shown, the power battery heating circuit also includes a pre-charging circuit 7 connected in parallel with the main positive relay 11.

[0039] The pre-charging circuit 7 includes a pre-charging resistor 71 and a pre-charging relay 72. The two ends of the pre-charging resistor 71 are connected to one end of the pre-charging relay 72 and one end of the main positive relay 11, respectively. The other end of the pre-charging relay 72 is connected to the other end of the main positive relay 11.

[0040] When a vehicle or other equipment starts, directly closing the main positive relay can cause a massive inrush current due to the large capacitors at the load terminals, such as those in the motor controller. These capacitors are initially at zero voltage, effectively short-circuiting, leading to a very large instantaneous inrush current. The pre-charge circuit 7, connected in parallel with the main positive relay 11, is a crucial circuit for protecting circuit components and ensuring stable system operation. During pre-charging, the pre-charge relay 72 closes before the main positive relay 11, allowing current to slowly charge the capacitors at the load terminals through the pre-charge resistor 71. When the capacitor voltage rises to a certain level, approaching the power supply voltage, the pre-charge relay 72 opens, and then the main positive relay 11 closes. At this point, because the voltage difference between the capacitor and the power supply voltage is small, the inrush current generated at the moment of closure is greatly reduced. The main function of the pre-charge resistor 71 is to limit the current during pre-charging. When the circuit begins pre-charging, current flows through the pre-charge resistor 71 to the capacitors and other components at the load terminals. Due to the current-limiting effect of the resistor, the excessive current generated at the moment of power-on due to the capacitors effectively short-circuiting is avoided, thus protecting the main positive relay 11 and other circuit components from damage caused by large current surges.

[0041] In some of these embodiments, such as Figure 1 As shown, the power battery heating circuit also includes a shunt 8, one end of which is connected to the negative terminal of the battery pack 2, and the other end of which is connected to the other end of the heating film 3.

[0042] The shunt 8 is an instrument used to measure large currents. When a large current passes through the shunt 8, according to Ohm's law, a voltage drop proportional to the current magnitude is generated across the shunt 8. For example, for a shunt with a known resistance, the magnitude of the current can be calculated using Ohm's law by measuring the voltage drop across it. This voltage drop is typically in the millivolt (mV) range, facilitating subsequent measurement by other instruments. For instance, in this embodiment, a 500A (ampere) shunt can be used, indicating that this shunt is primarily used to measure currents up to 500A.

[0043] In some embodiments, the power battery heating circuit further includes: a voltage sensor disposed in the battery pack 2 for collecting the voltage of the battery pack 2; and a temperature sensor disposed in the battery pack 2 for collecting the temperature status of the battery pack 2.

[0044] During battery charging and discharging, temperature changes occur. Temperature sensors accurately measure the battery temperature in real time, ensuring it operates within a safe temperature range and preventing overheating or overcooling. This avoids performance degradation, shortened lifespan, and even safety hazards such as thermal runaway, fire, or explosion caused by abnormal temperatures. Real-time measurement of the battery pack or individual cell voltage provides insight into the battery's operating voltage state, helping to understand its charge / discharge status and remaining capacity. Various sensors are used to collect the voltage and temperature of the battery pack under the control of the Battery Thermal Management System (BMS). On one hand, the BMS can cool or heat the battery based on temperature and detect abnormal voltage fluctuations. On the other hand, the BMS can precisely control the charging and discharging process based on information from the voltage sensors, combined with parameters such as current and temperature, preventing overcharging and over-discharging, ensuring the battery operates within a safe voltage range, extending battery life, and improving battery efficiency and performance.

[0045] In some embodiments, the power battery heating circuit further includes a battery management system, which is signal-connected to the relay group 1, temperature sensor, voltage sensor, and shunt 8.

[0046] The BMS is connected to the relays, temperature sensors, voltage sensors, and shunt signals in relay group 1. The software algorithms in the BMS can analyze and process the collected voltage data, temperature status, current, etc., to achieve functions such as battery status estimation, fault diagnosis, and protection. For example, by real-time monitoring and analysis of voltage data, it can determine whether the battery is overcharged, over-discharged, or whether the voltage of individual cells is balanced.

[0047] When fast charging is started, if the BMS detects that the temperature of the battery pack 2 is lower than a certain threshold (e.g., 0°C), the battery pack 2 needs to be heated before charging. The BMS controls the fast charging relay 12 and the heating relay 14 to close, so that the circuit between the battery pack 2 and the heating film 3 is disconnected. After the BMS detects that the temperature of the battery pack 2 is higher than the certain threshold, it controls the main positive relay 11 to close, so that the battery pack 2 is connected to the fast charging circuit for charging.

[0048] When starting the discharge, if the BMS detects that the temperature of the battery pack 2 is lower than a certain threshold (e.g., 0°C), the battery pack 2 needs to be heated before discharging. The BMS controls the main positive relay 11 and the heating relay 14 to close, so that the circuit between the battery pack 2 and the discharge interface 4 is in the open state. After the BMS detects that the temperature of the battery pack 2 is higher than the certain threshold, it controls the discharge negative relay 13 to close, so that the battery pack 2 can supply power to the external vehicle through the discharge interface 4.

[0049] In some embodiments, the battery pack 2 includes several battery groups, one end of which is connected to the main positive relay 11 and the other end of which is connected to the discharge negative relay 13.

[0050] The battery pack can be a storage battery.

[0051] The present embodiment will now be described and illustrated through preferred embodiments.

[0052] Figure 2 This is a schematic diagram of the power battery heating circuit in this embodiment, as shown below. Figure 2 As shown, the power battery heating circuit includes: a main fuse, a battery pack, a heating film, a discharge interface, a charging interface, a BMS (Battery Thermal Management System) chip, a main positive relay, a fast charging relay, a discharge negative relay, a pre-charge relay, a pre-charge resistor, a shunt, and a heating relay.

[0053] One end of the main positive relay is connected to the positive terminal of the battery pack via the main fuse. The negative terminal of the battery pack is connected to one end of the discharge negative relay. The other end of the discharge negative relay is connected to the negative terminal of the discharge interface. The positive terminal of the discharge interface is connected to the other end of the main positive relay, one end of the fast charging relay, and one end of the heating relay. The other end of the fast charging relay is connected to the positive terminal of the charging interface. The other end of the heating relay is connected to one end of the heating film. The other end of the heating film is connected to the negative terminal of the charging interface.

[0054] The two ends of the pre-charge resistor are connected to one end of the pre-charge relay and one end of the main positive relay, respectively. The other end of the pre-charge relay is connected to the other end of the main positive relay. One end of the shunt is connected to the negative terminal of the battery pack, and the other end of the shunt is connected to the other end of the heating film. The battery pack also contains temperature and voltage sensors. The BMS is connected to each relay, temperature sensor, voltage sensor, and shunt via pins, and performs voltage and temperature sampling or relay opening and closing under the control of the BMS.

[0055] When fast charging is initiated, if the BMS detects that the temperature of battery pack 2 is below a specific threshold (e.g., 0°C), the battery pack needs to be heated before charging. The BMS controls the fast charging relay and heating relay to close, disconnecting the circuit between the battery pack and the heating film. The charging current for the heating film is entirely provided by the charger (charging pile, charging equipment, etc.) through the charging interface. There is no situation where the battery pack needs to provide current to the heating film, or where excess current from the heating film flows to the battery pack. A fast charging circuit is formed between the positive terminal of the charging interface, the fast charging relay, the heating relay, the heating film, and the negative terminal of the charging interface. The heating relay and the heating film form a heating circuit; when the heating relay is closed, the heating film heats the battery pack. Once the BMS detects that the battery pack temperature is above the specific threshold, it controls the main positive relay to close, connecting the battery pack to the fast charging circuit for charging.

[0056] During initial discharge, if the BMS detects that the battery pack temperature is below a specific threshold (e.g., 0°C), the battery pack needs to be heated before discharge. The BMS controls the main positive relay and the heating relay to close, disconnecting the circuit between the battery pack and the discharge interface. The battery pack is then heated via a heating film. A discharge heating circuit is formed between the positive terminal of the battery pack, the main positive relay, the heating relay, the heating film, and the negative terminal. When the heating relay is closed, the battery pack is heated via the heating film. Once the BMS detects that the battery pack temperature is above the specific threshold, it controls the negative discharge relay to close, allowing the battery pack to supply power to the vehicle through the discharge interface.

[0057] This embodiment disconnects the circuit between the battery pack and the heating film during low-temperature fast charging heating, preventing the battery pack from supplying current to the heating film or excess current from flowing into the battery pack. This avoids over-discharge and over-charge of the battery cells. Similarly, during low-temperature discharge heating, it disconnects the circuit between the battery pack and the discharge interface, preventing over-discharge of the battery cells. This solves the problem of overcharging or over-discharging cells during low-temperature charging and discharging, better protecting the cells and extending battery life. Furthermore, this solution requires only one discharge negative relay, eliminating the need for a heating negative relay, thus saving costs.

[0058] This embodiment also provides an electric vehicle, including any of the above-mentioned power battery heating circuits. When the electric vehicle is charged at low temperatures or the battery pack is discharged at low temperatures, the battery pack cells will not be overcharged or over-discharged, which can better protect the cells and extend the battery life.

[0059] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0060] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0061] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or alternative to other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0062] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A power battery heating circuit, characterized in that, include: The relay group (1), battery pack (2), heating film (3), discharge interface (4), and charging interface (5); the relay group (1) includes: main positive relay (11), fast charging relay (12), discharge negative relay (13), and heating relay (14); One end of the main positive relay (11) is connected to the positive terminal of the battery pack (2), the negative terminal of the battery pack (2) is connected to one end of the discharge negative relay (13), the other end of the discharge negative relay (13) is connected to the negative terminal of the discharge interface (4), the positive terminal of the discharge interface (4) is connected to the other end of the main positive relay (11), one end of the fast charging relay (12), and one end of the heating relay (14), the other end of the fast charging relay (12) is connected to the positive terminal of the charging interface (5), the other end of the heating relay (14) is connected to one end of the heating film (3), and the other end of the heating film (3) is connected to the negative terminal of the charging interface (5).

2. The power battery heating circuit according to claim 1, characterized in that, Also includes: The main fuse (6) is disposed between the battery pack (2) and the main positive relay (11).

3. The power battery heating circuit according to claim 1, characterized in that, Also includes: A pre-charging circuit (7) connected in parallel with the main positive relay (11).

4. The power battery heating circuit according to claim 3, characterized in that, The pre-charging circuit (7) includes a pre-charging resistor (71) and a pre-charging relay (72). The two ends of the pre-charging resistor (71) are respectively connected to one end of the pre-charging relay (72) and one end of the main positive relay (11). The other end of the pre-charging relay (72) is connected to the other end of the main positive relay (11).

5. The power battery heating circuit according to claim 1, characterized in that, Also includes: A shunt (8) is connected at one end to the negative terminal of the battery pack (2) and at the other end to the other end of the heating film (3).

6. The power battery heating circuit according to claim 1, characterized in that, Also includes: A temperature sensor is installed in the battery pack (2) to collect the temperature status of the battery pack (2).

7. The power battery heating circuit according to claim 1, characterized in that, Also includes: A voltage sensor is installed in the battery pack (2) to collect the voltage of the battery pack (2).

8. The power battery heating circuit according to claim 1, characterized in that, Also includes: The battery management system is connected to the relay group (1), temperature sensor, voltage sensor, and shunt (8) via signal connection.

9. The power battery heating circuit according to claim 1, characterized in that, The battery pack (2) includes several battery groups, one end of which is connected to the main positive relay (11), and the other end is connected to the discharge negative relay (13).

10. An electric vehicle, characterized in that, Includes the power battery heating circuit as described in any one of claims 1 to 9.

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