Heating system for heating a power battery, and an electric vehicle

Abstract

A heating system for heating a power battery and an electric vehicle are provided. The power battery includes a first battery cell group (1) and a second battery cell group (2) connected in series. The heating system includes an inverter (3), an AC motor (4), a first controller (6), and a connection line (S1), in which the intermediate points of three bridge arms of the inverter (3) are connected to the tips of three-phase coils of the AC motor (4) in one-to-one correspondence, the first controller (6) is used to input a driving signal to the inverter (3), the first battery cell group (1), the second battery cell group (2), the inverter (3), the AC motor (4), and the connection line (S1) constitute an AC self-heating loop, and at least one heating device (7) is connected in series to the connection line (S1), and the heating device (7) is used to heat the first battery cell group and / or the second battery cell group.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure claims priority to and the benefit of Chinese Patent Application No. 202221000901.7, entitled "HEATING SYSTEM FOR HEATING POWER BATTERY, AND ELECTRIC VEHICLE," filed on April 28, 2022. The entire contents of the above-mentioned application are incorporated herein by reference.

[0002] The present disclosure relates to the field of vehicle technology, and more particularly to a heating system for heating a power battery, and an electric vehicle. [Background technology]

[0003] The characteristics of power batteries are greatly affected by the ambient temperature. Especially in low temperature environment, the energy and power characteristics of lithium-ion power batteries will be significantly attenuated. Therefore, the battery needs to be heated at low temperature. How to improve the heating performance of power batteries in electric vehicles becomes a major challenge. Summary of the Invention [Problem to be solved by the invention]

[0004] The aim of the present disclosure is to provide a new technical solution of a heating system for heating a power battery.

[0005] Another object of the present disclosure is to provide a new technical solution for an electric vehicle, which includes a power battery and a heating system for heating the power battery. [Means for solving the problem]

[0006] According to a first aspect of the present disclosure, a heating system for heating a power battery is provided. The power battery includes a first battery core group and a second battery core group connected in series. The heating system includes an inverter, an AC motor, a first controller, and one connection line. The inverter includes three bridge arms, and a positive electrode of the power battery is connected to an upper bridge arm of the inverter, and a negative electrode of the power battery is connected to a lower bridge arm of the inverter. The intermediate points of the three bridge arms of the inverter are respectively connected to the tip ends of the three-phase coils of the AC motor, and the end ends of the AC motor are connected together to form a neutral point. A first end of the connection line is connected to the neutral point of the AC motor, and a second end of the connection line is connected to a connection point between the first battery core group and the second battery core group. The first controller is configured to input a driving signal to the inverter. The first battery core group, the second battery core group, the inverter, the AC motor, and the connection line constitute an AC self-heating loop. At least one heating device is connected in series to the connection line, and the heating device is configured to heat the first battery core group and / or the second battery core group.

[0007] According to one embodiment of the present disclosure, a heating device is attached to a surface of the first battery core group and / or a surface of the second battery core group.

[0008] According to one embodiment of the present disclosure, the heating device is disposed on a first surface of the first battery core group and / or a first surface of the second battery core group, wherein the first surface of the first battery core group is a surface formed by stacking battery core units in the first battery core group, and the first surface of the second battery core group is a surface formed by stacking battery core units in the second battery core group.

[0009] According to one embodiment of the present disclosure, the heating device is disposed on a second surface of the first battery core group and / or a second surface of the second battery core group, wherein the second surface of the first battery core group is a surface of at least one battery core unit in the first battery core group, and the second surface of the second battery core group is a surface of at least one battery core unit in the second battery core group.

[0010] According to one embodiment of the present disclosure, the second surface is a surface facing an adjacent battery core unit.

[0011] According to one embodiment of the present disclosure, the deployment location of the heating device corresponds to the center of the battery core unit.

[0012] According to an embodiment of the present disclosure, the heating device corresponds to a low temperature area of ​​the first battery core group and / or a low temperature area of ​​the second battery core group, the low temperature area being an area where the temperature of the surface of the battery core group is below a first preset value.

[0013] According to one embodiment of the present disclosure, a switch is disposed in the connecting line. The heating system further includes a second controller configured to control the switch to turn on / off the connecting line.

[0014] According to one embodiment of the present disclosure, a protection circuit is disposed on the connection line.

[0015] According to a second aspect of the present disclosure, there is provided an electric vehicle comprising a power battery and a heating system according to any one of the first aspects.

[0016] Based on the heating system for heating the power battery and the electric vehicle of the present disclosure, one connection line is arranged from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group, and a heating device for heating the power battery is connected in series with the connection line. In addition, the heating system heats the power battery in two ways, namely, self-heating by excitation current and heating by external thermoelectric conversion, so that the heating effect of the power battery is more uniform.

[0017] Other features and advantages of the present disclosure will become apparent based on the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

[0018] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the present disclosure and, together with the description of the present disclosure, serve to explain the principles of the disclosure. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram of a heating system for heating a power battery according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a specific circuit diagram of a heating system for heating a power battery according to one embodiment of the present disclosure. [Diagram 3] FIG. 11 is a specific circuit diagram of a heating system for heating a power battery according to another embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic structural diagram of a battery core group according to an embodiment of the present disclosure. [Diagram 5] FIG. 13 is a schematic structural diagram of a battery core group according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0021] The following description of at least one example embodiment is merely exemplary in nature and is in no way intended to serve as a limitation on the present disclosure and its application or uses.

[0022] It should be noted that like numbers and letters refer to like items in the following attached drawings, and therefore, once an item is defined in a figure, no further discussion of the item in subsequent attached drawings is required.

[0023] In an electric vehicle, an inverter is connected between a power battery and an AC motor. One of the main functions of the inverter is to convert the DC output by the power battery into AC to drive and rotate the AC motor, thereby driving and rotating the wheel end. In the power battery heating solution in one embodiment of the present disclosure, a circuit topology between the power battery, the inverter, and the AC motor is used to heat the power battery for temperature increase.

[0024] In this embodiment of the present disclosure, the power battery includes a first battery core group and a second battery core group connected in series, and the heating system for heating the power battery includes an inverter, an AC motor, a first controller, and one connection line. The inverter includes three bridge arms, and the positive electrode of the power battery is connected to the upper bridge arm of the inverter, and the negative electrode of the power battery is connected to the lower bridge arm of the inverter. The intermediate points of the three bridge arms of the inverter are respectively connected to the tip ends of the three-phase coils of the AC motor, and the end ends of the AC motor are connected together to form a neutral point. The first end of the connection line is connected to the neutral point of the AC motor, and the second end of the connection line is connected to the connection point between the first battery core group and the second battery core group.

[0025] The first battery core group, the second battery core group, the inverter, the AC motor, and the connecting line constitute an AC self-heating loop. The first controller is configured to input a driving signal to the inverter, and under the action of the driving signal, the inverter alternately turns on the first battery core group and the AC motor, and the second battery core group and the AC motor, so that the first battery core group and the second battery core group alternately charge each other, thereby heating the first battery core group and the second battery core group. At least one heating device is connected in series to the connecting line, and the heating device is configured to heat the first battery core group and / or the second battery core group. The heating method by which the heating device heats the first battery core group and / or the second battery core group is thermoelectric conversion. Under the action of the current in the connecting line, the electric energy is converted into thermal energy, so that the temperature of the heating device increases. The heating device, as it increases in temperature, can transfer heat to the first battery core group and / or the second battery core group.

[0026] Based on the heating system for heating a power battery provided in this embodiment of the present disclosure, a connection line is added based on the original circuit topology of the electric vehicle. The connection line is from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group. The first battery core group and the second battery core group can alternately charge each other by using the connection circuit. That is, the battery cores of the power battery are self-heated by using the excitation current. In this case, the modification to the original circuit of the electric vehicle is small, and it is simple and easy to implement the solution.

[0027] That is, in this embodiment of the present disclosure, in addition to self-heating the battery core by using the excitation current, the heating device is further configured to perform thermoelectric conversion heating from outside the battery core to the battery core. The heating system heats the power battery in two ways, namely, self-heating by the excitation current and heating by external thermoelectric conversion, so that the heating effect of the power battery is more uniform. As shown in Figures 1 to 3, the following describes the heating system for heating the power battery provided in this embodiment of the present disclosure.

[0028] As shown in Figures 1 to 3, the power battery includes a first battery core group 1 and a second battery core group 2 connected in series, and the heating system includes an inverter 3, an AC motor 4, a first controller 6, and one connection line S1.

[0029] The AC motor 4 is star-connected, with the three ends of the three-phase coils (coil A, coil B, and coil C) connected together as a common end, which is the neutral point N of the AC motor 4.

[0030] The inverter 3 includes three bridge arms, and the positive electrode of the power battery is connected to the upper bridge arm of the inverter 3, and the negative electrode of the power battery is connected to the lower bridge arm of the inverter 3. The midpoints of the three bridge arms of the inverter 3 are respectively connected to the tips of the three-phase coils of the AC motor.

[0031] A first end of the connection line S1 is connected to the neutral point N of the AC motor, and a second end of the connection line S1 is connected to a connection point P between the first battery core group and the second battery core group.

[0032] In one example, the first battery core group 1 and the second battery core group 2 belong to the same battery pack, and the battery pack includes a common positive port, a common negative port, and a third port led out from the connection point P. The second end of the connection line S1 is connected to the connection point P between the first battery core group 1 and the second battery core group 2 via the third port. In another example, the first battery core group 1 and the second battery core group 2 belong to different battery packs.

[0033] In one example, the first battery core group 1 and the second battery core group 2 belong to the same battery pack, and the electromotive force of the first battery core group 1 is the same as the electromotive force of the second battery core group 2. That is, the second end of the connection line S1 is connected to an equipotential point of the battery pack. The equipotential point means that the absolute value of the voltage difference from that point to the total positive port of the battery pack is equal to the absolute value of the voltage difference from that point to the total negative port of the battery pack. In one example, the first battery core group 1 and the second battery core group 2 belong to the same battery pack, and the electromotive force of the first battery core group 1 is different from the electromotive force of the second battery core group 2. That is, the second end of the connection line S1 is connected to an unequal potential point of the battery pack. An inequipotential point means that the absolute value of the voltage difference from that point to the combined positive port of the battery pack is not equal to the absolute value of the voltage difference from that point to the combined negative port of the battery pack.

[0034] 2, the battery core units included in the first battery core group 1 and the battery core units included in the second battery core group 2 are of the same type but different in quantity, therefore, the electromotive force of the first battery core group 1 is different from that of the second battery core group 2, and the second end of the connection line S1 is connected to the unequal potential point of the battery pack.

[0035] The first controller 6 inputs a drive signal to the inverter 3 to control the inverter 3, thereby alternately turning on the first battery core group 1 and the AC motor 4 and the second battery core group 2 and the AC motor 4, so that the first battery core group 1 and the second battery core group 2 alternately charge each other, thereby self-heating the battery cores.

[0036] In one example, as shown in FIG. 1 and FIG. 2, the inverter 3 includes IGBT T1, IGBT T2, IGBT T3, IGBT T4, IGBT T5, and IGBT T6. The IGBTs T1 to T6 form three bridge arms. The IGBT (Insulated Gate Bipolar Transistor) is a composite voltage-driven power semiconductor device that includes a BJT (Bipolar Junction Transistor) and a MOS transistor (Meial-Oxide-Semiconductor), and has the advantages of the high input impedance of a MOSFET field effect transistor and the low turn-on voltage drop of a GTR (Giant Transistor). As shown in FIG. 2, in the inverter 3, each IGBT is further connected in parallel with a diode, which can play the role of circuit protection. In another embodiment, the IGBTs T1 to T6 may alternatively be replaced with MOS transistors, respectively. In another embodiment, IGBTs T1-T6 may alternatively each be replaced with a silicon carbide (SiC) power tube.

[0037] In this embodiment of the present disclosure, as shown in Figures 2 and 3, the first controller 6 outputs six drive signals Q1 to Q6. The drive signal Q1 is applied to the IGBT T1, the drive signal Q2 is applied to the IGBT T2, the drive signal Q3 is applied to the IGBT T3, the drive signal Q4 is applied to the IGBT T4, the drive signal Q5 is applied to the IGBT T5, and the drive signal Q6 is applied to the IGBT T6. By applying the drive signals Q1 to Q6 to the IGBTs T1 to T6, the first controller 6 alternately turns on the loop of the first battery core group 1 and the AC motor 4, and the loop of the second battery core group 2 and the AC motor 4, so that the first battery core group 1 and the second battery core group 2 alternately charge each other. In one example, the first battery core group 1 discharges, and the inverter 3 converts the direct current output by the first battery core group 1 into alternating current and inputs the alternating current to the AC motor 4, which stores electrical energy in a coil to charge the second battery core group 2. Then, the second battery core group 2 discharges, and the inverter 3 converts the direct current output by the second battery core group 2 into alternating current and inputs the alternating current to the AC motor 4, which stores electrical energy in a coil to charge the first battery core group 1. In a cyclical manner, the first battery core group 1 and the second battery core group 2 alternately charge each other by using the AC motor 4 to self-heat the battery cores.

[0038] As shown in FIG. 1 and FIG. 2, in this embodiment of the present disclosure, at least one heating device 7 is connected in series to the connection line S1, and the heating device 7 is configured to heat the first battery core group 1 and / or the second battery core group 2. The heating method by which the heating device 7 heats the first battery core group 1 and / or the second battery core group 2 is thermoelectric conversion. Under the action of the current of the connection line S1, the electric energy is converted into thermal energy, so that the temperature of the heating device 7 increases. The heating device 7 with the increasing temperature transfers heat to the first battery core group 1 and / or the second battery core group 2.

[0039] That is, in this embodiment of the present disclosure, in addition to self-heating the battery core by using the excitation current, the heating device 7 is further configured to perform thermoelectric conversion heating from outside the battery core to the battery core. The heating system heats the power battery in two ways, namely, self-heating by the excitation current and heating by external thermoelectric conversion, so that the heating effect of the power battery is more uniform.

[0040] In one example, the form, model, and heating efficiency of the heating device 7 connected in series to the connection line S1 may be flexibly designed based on actual requirements. The specific installation location of the heating device 7 may alternatively be flexibly designed based on the space environment and heating requirements. In one example, the device selection and layout may be performed for the heating device 7 based on the results of actual testing or simulation experiments.

[0041] In one example, multiple heating devices are connected in series to the connection line S1, and the forms, models, and heating efficiencies of the multiple heating devices may be the same or different. The specific quantity and distribution locations of the multiple heating devices may be flexibly designed based on the space environment and heating requirements. In one example, device selection and layout may be performed on the heating devices based on the results of actual tests or simulation experiments.

[0042] In this embodiment of the present disclosure, the heating device can be any one of a heating film, a heating plate, or a heating wire. The heating device can also be any one of a resistive heating film, a PTC (Positive Temperature Coefficient) heater, a vortex heater, a ceramic heater, or a silicone rubber heating plate, or can be another type of heating device. For example, the PTC heater and the resistive heating film are both connected in series to the connecting line S1.

[0043] In one example, in order to heat the first battery core group 1 and / or the second battery core group 2, a heating device is attached to a surface of the first battery core group 1 and / or a surface of the second battery core group 2.

[0044] In one example, as shown in Fig. 3, two heating devices are connected in series to the connection line S1. One heating device is attached to a surface of a first battery core group and configured to heat the first battery core group. The other heating device is attached to a surface of a second battery core group and configured to heat the second battery core group.

[0045] In one example, the heating device is disposed on a second surface of the first battery core group and / or a second surface of the second battery core group, the second surface of the first battery core group being a surface of at least one battery core unit in the first battery core group, and the second surface of the second battery core group being a surface of at least one battery core unit in the second battery core group. In one example, the second surface can be a surface of a battery core unit in the battery core group.

[0046] For example, if the battery core unit is blade-shaped, the heating device can be attached to the top or bottom surface of the battery core unit. For example, if the battery core unit is square-shaped, the heating device can be attached to any surface of the battery core unit. For example, if the battery core unit is cylindrical, the battery core unit has three surfaces including two circular end surfaces and one curved surface, and the heating device can be attached to the curved surface.

[0047] In another embodiment, the second surface may further refer to a surface facing an adjacent battery core unit.

[0048] In this embodiment of the present disclosure, the first battery core group and the second battery core group can be formed by stacking a plurality of battery core units, and the battery core unit can include cells or battery modules. The stacking can be set in the thickness direction of the battery core unit, or in the length or width direction of the battery core unit.

[0049] In one example, the heating device is disposed on a first surface of the first battery core group and / or a first surface of the second battery core group, the first surface of the first battery core group being a surface formed by stacking the battery core units in the first battery core group, and the first surface of the second battery core group being a surface formed by stacking the battery core units in the second battery core group. In this way, the heating device can approach multiple battery core units in the battery core group at the same time, so that the multiple battery core units in the first battery core group are heated at the same time, thereby achieving a more uniform heating effect. The surface formed by stacking may be in a left-right direction or a top-bottom direction.

[0050] For example, as shown in FIG. 4, the first battery core group is formed by stacking a plurality of blade-shaped battery core units, the battery core units are stacked to form a stacking surface 101 and a stacking surface 102, and the heating device is disposed on the stacking surface 101 or the stacking surface 102. For example, as shown in FIG. 5, the second battery core group is formed by stacking a plurality of cylindrical battery core units, the circular end surfaces at both ends of the plurality of battery core units respectively form a stacking surface, and the heating device is disposed on the stacking surface. Alternatively, the middle curved surfaces of the plurality of battery core units form a stacking surface, and the heating device is disposed on the stacking surface.

[0051] In one example, the battery core units are stacked in the same orientation to form a plurality of first surfaces, and the heating device is disposed on the first surface with a relatively large area, so that the heating device can be easily designed and laid out. For example, the heating device is disposed on the first surface with a relatively large area. For the same load power, a heating device in the form of a heating film may be selected. Since the heating film has a larger contact area, the battery core group is heated more uniformly.

[0052] In one example, the heating device is arranged to correspond to the center of the battery core unit. When the battery is heated by using an excitation current, the current density inside the battery core unit is distributed unevenly, and a relatively large temperature difference in the battery core unit is often formed, and the temperature at both ends of the battery core unit is relatively high and the temperature in the middle is relatively low. By arranging the heating device to correspond to the center of the battery core unit, the low temperature area of ​​the battery core unit can be selectively heated locally, thereby greatly reducing the temperature difference between different areas of the battery core unit and enhancing the uniformity of the overall temperature distribution.

[0053] In one example, the heating device corresponds to a low temperature area of ​​the first battery core group and / or a low temperature area of ​​the second battery core group. The low temperature area of ​​the battery core group is an area where the temperature of the surface of the battery core group is less than a first preset value. The first preset value is, for example, 10 degrees Celsius. The first preset value can correspond to an interval range, for example, 10-15 degrees Celsius, and the first preset value is set within the interval range based on the operating condition. In one example, the low temperature area of ​​the battery core group is a target area, and the temperature of the target area is lower than the first preset value and is at least a second preset value, for example, 5 degrees Celsius, lower than the temperature of the high temperature area of ​​the battery core group.

[0054] 4, a first battery core group is formed by stacking a plurality of blade-shaped battery core units, the battery core units are stacked to form a stacking surface 101 and a stacking surface 102, and a heating device is disposed on the stacking surface 101 or the stacking surface 102, where the heating device corresponds to the center of the battery core unit. In one example, the stacking surface 102 has a large area, and the heating device is disposed on the stacking surface 102, where the heating device corresponds to the center of the battery core unit.

[0055] As shown in FIG. 1-FIG. 3, the switch 5 is disposed on the connection line S1, and the heating system further includes a second controller 9. The second controller 9 is configured to control the on / off state of the switch 5 so that the connection line S1 is turned on when the power battery needs to be heated, and turned off when the power battery does not need to be heated, to ensure the safety of the vehicle and the power battery. For example, the second controller 9 controls the switch 5 to be turned off when the electric vehicle is in a running state, to ensure the safety of the vehicle. In one example, the first controller 6 and the second controller 9 may be integrated together.

[0056] As shown in FIGS. 1-3, a protection circuit 8, such as a fuse and a relay, is disposed in the connection line S1 to improve the safety of the battery heating process.

[0057] In one example, the material of the conductor used in the connection circuit S1 is a metal with good electrical conductivity, such as copper and aluminum, or may be a carbon-based material with good electrical conductivity.

[0058] 1 further illustrates a distribution box of the electric vehicle, which distributes power primarily based on the power load of the electric vehicle.

[0059] Based on the heating system for heating a power battery provided in this embodiment of the present disclosure, a connection line is added based on the original circuit topology of the electric vehicle. The connection line is from the neutral point of the AC motor to the connection point between the first battery core group and the second battery core group. The changes to the original circuit of the electric vehicle are small, and the solution is simple and easy to implement.

[0060] Based on the heating system for heating a power battery provided in this embodiment of the present disclosure, by using the upper bridge arm and the lower bridge arm of the inverter in a time-division manner, the three inductance coils of the motor can be used to a large extent to generate an AC pulse current, thereby quickly heating two groups of battery cores.

[0061] In this embodiment of the present disclosure, at least one heating device is connected in series to the connection line, and the heating device is configured to heat the first battery core group and / or the second battery core group. The heating method by which the heating device heats the first battery core group and / or the second battery core group is thermoelectric conversion. Under the action of the current in the connection line, the electrical energy is converted into thermal energy, so that the temperature of the heating device increases. The heating device with the increasing temperature can transfer heat to the first battery core group and / or the second battery core group.

[0062] That is, in this embodiment of the present disclosure, in addition to self-heating the battery core by using the excitation current, the heating device 7 is further configured to perform thermoelectric conversion heating from outside the battery core to the battery core. The heating system heats the power battery in two ways, namely, self-heating by the excitation current and heating by external thermoelectric conversion, so that the heating effect of the power battery is more uniform.

[0063] In the heating process of a power battery, the frequency and magnitude of the charge / discharge current, i.e., the excitation current, are limited by the associated components. The heating system provided in this embodiment of the present disclosure can reduce the degree of limitation of the excitation current, thereby enabling the battery to be heated with a relatively large excitation current. In the self-heating operating state of a conventional battery pack, the maximum current of the inverter is limited by the minimum current of the allowable current of IGBTs T1-T6. However, in this embodiment of the present disclosure, the maximum current of the inverter is limited by the sum of the allowable currents of IGBTs T1, T2, and T3 and the sum of the allowable currents of IGBTs T4, T5, and T6.

[0064] The first controller in this embodiment of the present disclosure may include a processor, a memory, and a program or instructions stored in the memory and executable by the processor, the program or instructions, when executed by the processor, implementing self-heating of the power battery.

[0065] An embodiment of the present disclosure provides an electric vehicle including a power battery and a heating system for heating the power battery as described in any one of the preceding embodiments.

[0066] All of the embodiments herein are described in order, and for the same or similar parts of the embodiments, reference is made to these embodiments, and the description of each embodiment focuses on the differences from other embodiments. In the electric vehicle embodiment, for relevant details, please refer to the description of some of the heating system embodiments.

[0067] The embodiments of the present disclosure have been described above, and the above description is illustrative, not exhaustive, and is not limited to the disclosed embodiments. Many changes and modifications will be apparent to those skilled in the art without departing from the scope of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to allow those skilled in the art to understand the embodiments disclosed herein. [Explanation of symbols]

[0068] 1 First Battery Core Group 2 Second Battery Core Group P Connection Point 3 Inverter 4 AC motor N neutral point 5. Switch 6 First Controller S1 Connection Line 7 Heating Device 8 Protection circuit 9 Second Controller

Claims

1. A heating system for heating a power battery, the power battery comprising a first battery core group (1) and a second battery core group (2) connected in series, the heating system comprising an inverter (3), an AC motor (4), a first controller (6), and a connection line (S1); The inverter (3) has three bridge arms, and the positive electrode of the power battery is connected to the upper bridge arm of the inverter (3) and the negative electrode of the power battery is connected to the lower bridge arm of the inverter (3); The intermediate points of the three bridge arms of the inverter (3) are respectively connected to the tip ends of the three-phase coils of the AC motor (4), and the end ends of the AC motor (4) are connected together to form a neutral point (N); a first end of the connection line (S1) is connected to the neutral point (N) of the AC motor (4), and a second end of the connection line (S1) is connected to a connection point (P) between the first battery core group (1) and the second battery core group (2); The first controller (6) is configured to input a drive signal to the inverter (3); the first battery core group (1), the second battery core group (2), the inverter (3), the AC motor (4), and the connection line (S1) form an AC self-heating loop; A heating system, wherein at least one heating device (7) is connected in series to the connection line (S1), and the heating device (7) is configured to heat the first battery core group (1) and / or the second battery core group (2).

2. The heating system according to claim 1 , wherein the heating device (7) is attached to a surface of the first battery core group (1) and / or a surface of the second battery core group (2).

3. 2. The heating system of claim 1, wherein the heating device (7) is arranged on a first surface of the first battery core group (1) and / or a first surface of the second battery core group (2), the first surface of the first battery core group (1) being a surface formed by stacking battery core units in the first battery core group (1), and the first surface of the second battery core group (2) being a surface formed by stacking battery core units in the second battery core group.

4. 2. The heating system of claim 1, wherein the heating device (7) is arranged on a second surface of the first battery core group (1) and / or a second surface of the second battery core group (2), the second surface of the first battery core group (1) being a surface of at least one battery core unit in the first battery core group (1), and the second surface of the second battery core group (2) being a surface of at least one battery core unit in the second battery core group (2).

5. The heating system of claim 4 , wherein the second surface is a surface facing an adjacent battery core unit.

6. The heating system according to claim 3 or 4, wherein the deployment location of the heating device (7) corresponds to the center of a battery core unit.

7. The heating system according to any one of claims 1 to 5, wherein the heating device (7) corresponds to a low temperature area of ​​the first battery core group (1) and / or a low temperature area of ​​the second battery core group (2), the low temperature area being an area where the temperature of the surface of the battery core group is below a first preset value.

8. 2. The heating system of claim 1, wherein a switch (5) is arranged in the connecting line (S1), and the heating system comprises a second controller (9), the second controller (9) configured to control the switch (5) to turn the connecting line on and off.

9. 2. The heating system according to claim 1, wherein a protection circuit (8) is arranged in the connection line (S1).

10. An electric vehicle comprising a power battery and the heating system according to any one of claims 1 to 9.

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