Battery self-heating system and vehicle

Abstract

The present disclosure relates to a battery self-heating system and a vehicle, belonging to the technical field of electric vehicles. When one of the first battery pack and the second battery pack is in a discharging state, the other of the first battery pack and the second battery pack is in a charging state. In this way, the voltage fluctuations of the first battery pack and the second battery pack cancel each other out, resulting in a relatively small voltage fluctuation at the terminal of the power battery pack, thereby avoiding charging failure.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electric vehicles, and in particular, to a battery self-heating system and a vehicle. Background Art

[0002] In response to energy conservation and emission reduction, more and more electric vehicles have come into the public eye. When an electric vehicle is in a low-temperature environment, the low temperature reduces the activity of the positive and negative electrode materials of the battery and the electrolyte in the battery, and its charge and discharge performance will drop significantly. To ensure the power of the electric vehicle in a low-temperature environment, the battery of the electric vehicle can be heated to increase the temperature of the battery body to ensure the charge and discharge performance of the battery. In related technologies, the battery is heated by alternating charge and discharge between the battery pack and the energy storage element. However, in the current charge and discharge process, the terminal voltage of the battery pack fluctuates greatly. When the battery pack is connected to a charging pile for charging, this fluctuation may cause the charging to fail. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a battery self-heating system and a vehicle, aiming to solve the above technical problems.

[0004] To achieve the above purpose, on the one hand, the present disclosure provides a battery self-heating system applied to a vehicle. The system includes: a power battery pack, the power battery pack including a first battery group and a second battery group connected in series; a first self-heating module connected to the first battery group; a second self-heating module connected to the second battery group; and a controller connected to the first self-heating module and the second self-heating module. The controller controls the alternating charge and discharge between the first self-heating module and the first battery group, and the controller controls the alternating charge and discharge between the second self-heating module and the second battery group. When one of the first battery group and the second battery group is in a discharge state, the other of the first battery group and the second battery group is in a charging state.

[0005] Optionally, the battery self-heating system further includes: a controller, both the first multi-phase inverter bridge and the second multi-phase inverter bridge are connected to the controller; the controller is configured to, in a first preset state, control the lower arm of the first multi-phase inverter bridge to conduct, so as to control the first battery pack to discharge and charge the first multi-phase motor, and control the upper arm of the second multi-phase inverter bridge to conduct, so as to control the second capacitor to discharge and charge the second battery pack and the second multi-phase motor; the controller is further configured to, in a second preset state, control the upper arm of the first multi-phase inverter bridge to conduct, so as to control the first battery pack and the first multi-phase motor to discharge and charge the first capacitor, and control the lower arm of the second multi-phase inverter bridge to conduct, so as to control the second multi-phase motor to discharge and charge the second battery pack; the controller is further configured to, in a third preset state, control the upper arm of the first multi-phase inverter bridge to conduct, so as to control the first capacitor to discharge and charge the first multi-phase motor and the first battery pack, and control the lower arm of the second multi-phase inverter bridge to conduct, so as to control the second battery pack to discharge and charge the second multi-phase motor; the controller is further configured to, in a fourth preset state, control the lower arm of the first multi-phase inverter bridge to conduct, so as to control the first multi-phase motor to discharge and charge the first battery pack, and control the upper arm of the second multi-phase inverter bridge to conduct, so as to control the second battery pack and the second multi-phase motor to discharge and charge the second capacitor.

[0006] Optionally, the battery self-heating system further includes: a first switch, a second switch, and a third switch, wherein the first switch, the second switch, and the third switch are all two-position switches; the negative terminal of the first battery pack is connected to the stationary contact of the first switch, the first moving contact of the first switch is connected to the midpoint of the three-phase windings of the first multi-phase motor, and the second moving contact of the first switch is respectively connected to the positive terminal of the first capacitor, the positive terminal of the first multi-phase inverter bridge, the positive terminal of the second capacitor, and the positive terminal of the second multi-phase inverter bridge; the negative terminal of the first battery pack and the positive terminal of the second battery pack are both connected to the first moving contact of the second switch, the second moving contact of the second switch is respectively connected to the negative terminal of the second battery pack and the negative terminal of the second multi-phase inverter bridge, and the stationary contact of the second switch is respectively connected to the negative terminal of the first capacitor and the negative terminal of the first multi-phase inverter bridge; the first moving contact of the third switch is respectively connected to the second moving contact of the first switch and the midpoint of the first multi-phase motor, the second moving contact of the third switch is respectively connected to the negative terminal of the first battery pack and the positive terminal of the second battery pack, and the stationary contact of the third switch is connected to the midpoint of the three-phase windings of the second multi-phase motor. The first switch, the second switch, and the third switch are all connected to the controller.

[0007] Optionally, the controller is further configured to control the static contact of the first switch to connect to the second moving contact of the first switch, the static contact of the second switch to connect to the second moving contact of the second switch, and the third switch to disconnect, so as to control the first battery pack and the second battery pack to supply power to the first polyphase motor and the second polyphase motor to drive the vehicle.

[0008] Optionally, the battery self-heating system further includes: a fourth switch; one end of the fourth switch is respectively connected to the second moving contact of the first switch, the positive electrode of the second capacitor, and the positive electrode of the first polyphase inverter bridge, and the other end of the fourth switch is used to connect to the positive electrode of the DC charging pile. The controller is connected to the fourth switch, and the negative electrode of the DC charging pile is respectively connected to the negative electrode of the second capacitor and the negative electrode of the second polyphase inverter bridge; the controller is further configured to control the static contact of the first switch to connect to the first moving contact of the first switch, the static contact of the second switch to connect to the second moving contact of the second switch, the static contact of the third switch to connect to the first moving contact of the third switch, and the fourth switch to close, so as to control the DC charging pile to charge the first battery pack and the second battery pack through the first polyphase inverter bridge, the first polyphase motor, the second polyphase inverter bridge, and the second polyphase motor.

[0009] Optionally, the controller is further configured to, in a fifth preset state, control the upper bridge arm of the first polyphase inverter bridge and the upper bridge arm of the second polyphase inverter bridge to conduct, so as to control the current of the DC charging pile to charge the first battery pack and the second battery pack through the upper bridge arm of the first polyphase inverter bridge and the first polyphase motor, and to charge the first battery pack and the second battery pack through the upper bridge arm of the second polyphase inverter bridge and the second polyphase motor.

[0010] Optionally, the controller is further configured to, in a sixth preset state, control the lower bridge arm of the first polyphase inverter bridge and the lower bridge arm of the second polyphase inverter bridge to conduct, and charge the first battery pack and the second battery pack through the discharge of the first polyphase motor and the second polyphase motor.

[0011] Optionally, the duration of the fifth preset state is a first duration T1, the duration of the sixth preset state is a second duration T2, the discharge voltage of the DC charging pile is a first voltage U1, and the discharge voltage of the first polyphase motor and the second polyphase motor is a second voltage U2. Wherein, the following relationship exists among the first duration T1, the second duration T2, the first voltage U1, and the second voltage U2: U1*T1 = U2*(T1 + T2).

[0012] Optionally, the controller is further configured to control the static contact of the first switch to be connected to the second moving contact of the first switch, the static contact of the second switch to be connected to the second moving contact of the second switch, the third switch to be disconnected, and the fourth switch to be closed, so as to control the DC charging pile to charge the first battery pack and the second battery pack.

[0013] On the other hand, the present disclosure provides a vehicle including the above battery self-heating system.

[0014] For the battery self-heating system and the vehicle provided by the present disclosure, when one of the first battery pack and the second battery pack is in a discharging state, the other of the first battery pack and the second battery pack is in a charging state. In this way, the voltage fluctuations of the first battery pack and the second battery pack cancel each other out, resulting in a relatively small voltage fluctuation at the terminal of the power battery pack, thereby avoiding charging failure.

[0015] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0017] Figure 1 is a schematic diagram of a battery self-heating circuit in the prior art.

[0018] Figure 2 is a schematic diagram of another battery self-heating circuit in the prior art.

[0019] Figure 3 is a circuit diagram of a battery self-heating system provided by an embodiment of the present disclosure.

[0020] Figure 4 is a circuit diagram of a battery self-heating system provided by an embodiment of the present disclosure.

[0021] Figure 5 is a circuit diagram of another battery self-heating system provided by an embodiment of the present disclosure.

[0022] Figure 6 is a circuit diagram of another battery self-heating system provided by an embodiment of the present disclosure.

[0023] Figure 7 is a circuit diagram of another battery self-heating system provided by an embodiment of the present disclosure.

[0024] Figure 8 is a circuit diagram of another battery self-heating system provided by an embodiment of the present disclosure.

[0025] Figure 9 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0026] Figure 10 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0027] Figure 11 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0028] Figure 12 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0029] Figure 13 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0030] Figure 14 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0031] Figure 15 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0032] Figure 16 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0033] Description of reference numerals

[0034] E1 First battery pack, E2 Second battery pack

[0035] K1 First switch, K2 Second switch

[0036] K3 Third switch, K4 Fourth switch

[0037] C1 First capacitor, C2 Second capacitor

[0038] C3 Third capacitor, C4 Fourth capacitor

[0039] 1 First self - heating module, 2 Second self - heating module

[0040] 10 First multiphase inverter bridge, 20 Second multiphase inverter bridge

[0041] 30 First multiphase motor, 40 Second multiphase motor

[0042] 50 DC charging pile, 60 Third multiphase inverter bridge

[0043] 70 Third multiphase motor, 80 Fourth multiphase inverter bridge

[0044] 90 Fourth multiphase motor Detailed Embodiments

[0045] The following describes the detailed embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present disclosure, and are not used to limit the present disclosure.

[0046] It should be noted that all actions of obtaining signals, information, or data in the present disclosure are carried out on the premise of complying with the corresponding data protection regulations and policies of the country where the location is located, and with the authorization given by the owner of the corresponding device.

[0047] In response to energy conservation and emission reduction, more and more electric vehicles are chosen by more users. To improve the driving performance of electric vehicles, multi-motor electric vehicles, known for their strong power, have gradually come into the public eye. Strong power requires good charge and discharge performance of the battery. However, when an electric vehicle is in a low-temperature environment, especially below -10°C, the low temperature reduces the activity of the positive and negative electrode materials of the battery and the electrolyte in the battery, and its charge and discharge performance will drop significantly. To ensure the power of the electric vehicle in a low-temperature environment, the battery of the electric vehicle can be heated to increase the temperature of the battery body to ensure the charge and discharge performance of the battery.

[0048] Currently, there are two ways to heat the battery: external heating and internal heating. Among them, external heating heats the battery by adding additional heating equipment. This heating method increases the cost due to the additional heating equipment, and due to the relatively fast external heat dissipation and the certain distance between the external temperature and the internal battery, the heating efficiency is low. Another current heating method, the principle of internal heating mainly uses the battery to cycle charge and discharge, relying on the internal resistance of the battery to generate heat. For example, as Figure 1 shown in FIG. 2 of the self-heating system. In Figure 1 the self-heating system shown in FIG. 2, the battery pack alternates charge and discharge with the motor winding and capacitor. When the battery pack discharges to the motor winding and capacitor, the voltage of the battery pack drops. When the motor winding and capacitor charge the battery pack, the voltage of the battery pack rises. In the above voltage drop and boost methods, the battery voltage fluctuates greatly, and this fluctuation may damage the battery and reduce the service life of the battery. Moreover, the battery voltage fluctuation ∆U = I * Rcell. When the total internal resistance Rcell of the battery remains unchanged, the greater the battery current, the greater the voltage fluctuation of the battery. The large voltage fluctuation causes the charging pile to be unable to track the battery voltage in real time during direct connection charging, resulting in gun jumping or charging failure.

[0049] To solve the above problems, the present application provides a battery self-heating system applied to a vehicle. Please refer to Figure 3 , the battery self-heating system includes: a power battery pack, a first self-heating module 1, a second self-heating module 2, and a controller (not shown in the figure).

[0050] The power battery pack includes a first battery pack E1 and a second battery pack E2 connected in series.

[0051] The first self-heating module 1 is connected to the first battery pack E1.

[0052] The second self-heating module is connected to the second battery pack E2.

[0053] The controller is connected to the first self-heating module 1 and the second self-heating module 2. The controller controls the alternating charge and discharge between the first self-heating module 1 and the first battery pack E1, and the controller controls the alternating charge and discharge between the second self-heating module 2 and the second battery pack E2. And when one of the first battery pack E1 and the second battery pack E2 is in a discharge state, the other of the first battery pack E1 and the second battery pack E2 is in a charge state.

[0054] In the battery self-heating system provided in this embodiment, when one of the first battery pack and the second battery pack is in a discharge state, the other of the first battery pack and the second battery pack is in a charge state. In this way, the voltage fluctuations of the first battery pack and the second battery pack cancel each other out, so that the terminal voltage fluctuation of the power battery pack is small, thereby avoiding charging failure.

[0055] Optionally, please refer to Figure 4 , the first self-heating module 1 includes a first polyphase motor 30, a first capacitor C1 and the first polyphase inverter bridge 10. The second self-heating module 2 includes a second polyphase motor 40, a second capacitor C2 and a second polyphase inverter bridge 20.

[0056] The negative terminal of the first battery pack E1 is connected to the positive terminal of the second battery pack E2. The first capacitor C1 and the first polyphase inverter bridge 10 are connected in parallel. The second capacitor C2 and the second polyphase inverter bridge 20 are connected in parallel. The first polyphase inverter bridge 10 and the first polyphase motor 30 are connected in series and then connected in parallel with the first battery pack E1. The second polyphase inverter bridge 20 and the second polyphase motor 40 are connected in series and then connected in parallel with the second battery pack E2. Wherein, each phase of the motor windings of the first polyphase motor 30 is connected to each phase of the first polyphase inverter bridge 10 one by one, and each phase of the motor windings of the second polyphase motor 40 is connected to each phase of the second polyphase inverter bridge 20 one by one.

[0057] Among them, the first multi-phase inverter bridge and the first capacitor can be devices in the same multi-phase inverter, and the second multi-phase inverter bridge and the second capacitor can be devices in the same multi-phase inverter. Optionally, the first multi-phase inverter bridge 10 and the second multi-phase inverter bridge 20 can be three-phase inverter bridges, six-phase inverter bridges, etc. Correspondingly, the first multi-phase motor 30 and the second multi-phase motor 40 can be three-phase motors, six-phase motors, etc.

[0058] The first multi-phase inverter bridge 10 and the second multi-phase inverter 20 are used to control through on-off states that when the first battery pack E1 discharges to charge the first capacitor C1 or the first multi-phase motor 30, the second capacitor C2 or the second multi-phase motor 40 discharges to charge the second battery pack E2; when the first capacitor C1 or the first multi-phase motor 30 discharges to charge the first battery pack E1, the second battery pack E2 discharges to charge the second capacitor C2 or the second multi-phase motor 40, so that the first battery pack E1 and the second battery pack E2 are heated during the charging and discharging process to achieve multi-motor oscillation heating.

[0059] The on-off state refers to the closed or disconnected state of the upper bridge arm or lower bridge arm switch tube in the multi-phase inverter bridge. At most, only one of the upper bridge arm and the lower bridge arm of the same multi-phase inverter bridge is turned on. For example, if the switch tube of the upper bridge arm of the first multi-phase inverter bridge 10 is turned off, the switch tube of the lower bridge arm of the first multi-phase inverter bridge 10 is disconnected. The first battery group E1 and the second battery group E2 are alternately discharged through the on-off state of the first multi-phase inverter bridge 10, so that the total voltage fluctuation is small, reducing damage to the battery cells of the battery group.

[0060] The battery pack of the vehicle can be divided into a first battery pack E1 and a second battery pack E2, and the internal resistance Rcell of the battery pack is also divided into the internal resistance Rcell1 of the first battery pack E1 and the internal resistance Rcell2 of the second battery pack E2. In this embodiment, the second battery pack is charged and boosted and the first battery pack is discharged and reduced, or the first battery pack is discharged and boosted and the second battery pack is discharged and reduced, so that the total voltage fluctuation of the battery pack is small. Optionally, the discharge voltage of the first battery pack E1 drops ∆U1=I1*Rcell1, and the charging voltage of the second battery pack E2 increases ∆U2=I2*Rcell2, so that the total voltage fluctuation of the battery pack ∆U=∆U1+∆U2=0, where I1 is the current of the first battery pack and I2 is the current of the second battery pack. Or the charging voltage of the first battery pack E1 increases, and the discharge voltage of the second battery pack E2 decreases, so that the total voltage fluctuation of the battery pack is 0.

[0061] Optionally, when the battery cells of the battery pack are evenly divided, that is, when the two battery groups are evenly divided, that is, the internal resistance Rcell1 of the first battery group E1 is the same as the internal resistance Rcell2 of the second battery group E2, that is, Rcell1 = Rcell2, as long as I1 = I2 is ensured, the total voltage fluctuation of the battery pack can be made 0.

[0062] When the battery cells of the battery pack are not evenly divided, that is, the internal resistance Rcell1 of the first battery group E1 is not the same as the internal resistance Rcell2 of the second battery group E2, as long as the voltage drop of the first battery group is the same as the voltage rise of the second battery group, or the voltage rise of the first battery group is the same as the voltage drop of the second battery group, that is, I1 * Rcell1 = I2 * Rcell2.

[0063] That is, controlling the ratio of the self-heating currents of the first battery group E1 and the second battery group E2 to be I1 / I2 = Rcell2 / Rcell1 is sufficient. Assuming that the internal resistances of all battery cells are the same, then I1 / I2 = Rcell2 / Rcell1 = N2 / N1. Where N1 is the number of battery cells included in the first battery group E1, N2 is the number of battery cells included in the second battery group E2, Rcell1 is the total internal resistance of the first battery group E1, and Rcell2 is the total internal resistance of the second battery group E2.

[0064] Optionally, when the battery cells of the battery pack are divided into three groups, four groups or even more groups (n groups) in addition to being divided into the above two groups, correspondingly, there are n multi-phase motors and multi-phase inverter bridges matching each multi-phase motor, which are matched with n groups of battery packs. To ensure the stability of the total voltage of the battery pack, by controlling the actions of the bridge arms in the multi-phase inverter bridge, assuming that the number of battery cells included in the n groups of battery packs are N1, N2, N3... Nn respectively, the self-heating currents of the n groups of battery packs should satisfy the following relationship: I1 / I2 / I3 / ... / In = Nn / ... / N3 / N2 / N1.

[0065] Optionally, when there are m multi-phase motors and the multi-phase inverter bridges matching each of the m motors are connected in parallel to the same battery pack, control the sum of the currents flowing through each of the m multi-phase inverter bridges to be equal to the current of the battery pack, where the currents of each electronic control of the battery pack are not equal.

[0066] The battery self-heating system provided in this embodiment includes a first battery pack, a second battery pack, a first multiphase inverter bridge, a second multiphase inverter bridge, a first capacitor, a second capacitor, a first multiphase motor, and a second multiphase motor. By controlling the on-off states of the first multiphase inverter bridge and the second multiphase inverter bridge, when the first battery pack discharges to charge the first capacitor or the first multiphase motor, the second capacitor or the second multiphase motor discharges to charge the second battery pack, that is, the second battery pack is charged and boosted while the first battery pack is discharged and bucked. When the first capacitor or the first multiphase motor discharges to charge the first battery pack, the second battery pack discharges to charge the second capacitor or the second multiphase motor, that is, the first battery pack is discharged and boosted while the second battery pack is discharged and bucked. The final total voltage fluctuation is small when one battery pack is boosted and the other is bucked. During the charging and discharging process of the first battery pack and the second battery pack to increase the temperature, the smaller voltage fluctuation can reduce the damage to the battery pack.

[0067] Optionally, the battery self-heating system further includes: a controller (not shown in the figure), and both the first multiphase inverter bridge 10 and the second multiphase inverter bridge 20 are connected to the controller.

[0068] The controller is configured to, in a first preset state, control the lower arm of the first multiphase inverter bridge 10 to conduct, so as to control the first battery pack E1 to discharge to charge the first multiphase motor 30, and control the upper arm of the second multiphase inverter bridge 20 to conduct, so as to control the second capacitor C2 to discharge to charge the second battery pack E2 and the second multiphase motor 40.

[0069] Please refer to Figure 5 , in the first preset state, the controller controls the lower arm of the first multiphase inverter bridge 10 to conduct. The current flows out from the positive terminal of the first battery pack E1, and the current sequentially flows through the first multiphase motor 30 and the lower arm of the first multiphase inverter bridge 10 and returns to the negative terminal of the first battery pack E1, forming a discharge loop of the first battery pack E1. In this loop, the first battery pack E1 discharges to charge the multiphase windings of the first multiphase motor 30. At the same time, the controller controls the upper arm of the second multiphase inverter bridge 20 to conduct. The current flows out from the positive terminal of the second capacitor C2, sequentially flows through the upper arm of the second multiphase inverter bridge 20 and the second multiphase motor 40 and flows into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and then flows back to the negative terminal of the second capacitor C2 from the negative terminal of the second battery pack E2, forming a discharge loop of the second capacitor C2. In this loop, the second capacitor C2 discharges to charge the second battery pack E2 and the second multiphase motor 40.

[0070] The controller is further configured to, in a second preset state, control the upper bridge arm of the first multi-phase inverter bridge 10 to conduct, so as to control the first battery pack E1 and the first multi-phase motor 30 to discharge and charge the first capacitor C1, and control the lower bridge arm of the second multi-phase inverter bridge 20 to conduct, so as to control the second multi-phase motor 40 to discharge and charge the second battery pack E2.

[0071] Please refer to Figure 6 , in the second preset state, the controller controls the upper bridge arm of the first multi-phase inverter bridge 10 to conduct (the power switch device VT in the upper bridge arm can be closed, or the power switch device VT in the upper bridge arm can be disconnected, and the current flows through the diode VD), the current flows out from the positive terminal of the first battery pack E1, successively passes through the first multi-phase motor 30, the upper bridge arm of the first multi-phase inverter bridge 10 and the first capacitor C1, and then flows back to the negative terminal of the first battery pack E1 to form a loop. In the first preset state, the first multi-phase motor 30 stores electrical energy after charging. Therefore, in this loop, the first battery pack E1 and the first multi-phase motor 30 discharge to charge the first capacitor C1. At the same time, the controller controls the lower bridge arm of the second multi-phase inverter bridge to conduct. In the first preset state, the second multi-phase motor 40 stores electrical energy after charging. Due to the freewheeling characteristic of the second multi-phase motor 40, the second multi-phase motor 40 discharges, the current flows out from the midpoint n2 of the second multi-phase motor 40, flows into the positive terminal of the second battery pack E2 to charge the second battery pack E2, then flows out from the negative terminal of the second battery pack E2, flows into the lower bridge arm of the second multi-phase inverter bridge 20 and then returns to the second multi-phase motor 40. In this loop, the second multi-phase motor 40 discharges to charge the second battery pack E2.

[0072] The controller is further configured to, in a third preset state, control the upper bridge arm of the first multi-phase inverter bridge 10 to conduct, so as to control the first capacitor C1 to discharge and charge the first multi-phase motor 30 and the first battery pack E1, and control the lower bridge arm of the second multi-phase inverter bridge 20 to conduct, so as to control the second battery pack E2 to discharge and charge the second multi-phase motor 40.

[0073] Please refer to Figure 7, in the third preset state, the controller turns on the upper arm of the first three-phase inverter bridge 10. The current flows out from the positive terminal of the first capacitor C1, successively passes through the upper arm of the first three-phase inverter bridge 10 and the first three-phase motor 30, and then flows into the positive terminal of the first battery pack E1. After charging the first battery pack E1, the current flows out from the negative terminal of the first battery pack E1 and returns to the negative terminal of the first capacitor C1 to form a loop. Since the first capacitor C1 stores electrical energy during the second preset state, in this loop, the first capacitor C1 discharges to charge the first battery pack E1 and the first three-phase motor 30. At the same time, the controller turns on the lower arm of the second three-phase inverter bridge 20. The current flows out from the positive electrode of the second battery pack E2, successively passes through the second three-phase motor 40 and the lower arm of the second three-phase inverter bridge 20, and then flows back to the negative electrode of the second battery pack E2 to form a loop. In this loop, the second battery pack E2 discharges to charge the second three-phase motor 40.

[0074] The controller is further configured to, in the fourth preset state, turn on the lower arm of the first three-phase inverter bridge 10 to control the first three-phase motor 30 to discharge and charge the first battery pack E1, and turn on the upper arm of the second three-phase inverter bridge 20 to control the second battery pack E2 and the second three-phase motor 40 to discharge and charge the second capacitor.

[0075] Please refer to Figure 8 , in the fourth preset state, the controller turns on the lower arm of the first three-phase inverter bridge 10. In the third preset state, the first three-phase motor 30 stores electrical energy. Due to the freewheeling performance of the motor windings of the first three-phase motor 30, the current flows out from the first three-phase motor 30 and into the positive terminal of the first battery pack E1 to charge the first battery pack E1. Then, the current flows out from the negative terminal of the first battery pack E1, passes through the lower arm of the first three-phase inverter bridge 10 and returns to the first three-phase motor 30 to form a loop. In this loop, the first three-phase motor 30 discharges to charge the first battery pack E1. At the same time, the controller turns on the lower arm of the second three-phase inverter bridge 20. The current flows out through the second battery pack E2, successively passes through the second three-phase motor 40, the upper arm of the second three-phase inverter bridge 20 and the second capacitor C2, and then flows back to the negative terminal of the second battery pack E2. Since the second three-phase motor 40 has stored electrical energy in the third preset state, in this loop, the second battery pack E2 and the second three-phase motor 40 discharge to charge the second capacitor C2.

[0076] From Figures 5 - 8As can be seen from the self-heating process shown, in the first to fourth preset states, the charge and discharge states of the first battery E1 and the second battery E2 are always opposite. When the first battery E1 discharges, the second battery E2 charges; when the second battery E2 discharges, the first battery E1 charges. Therefore, in the self-heating system disclosed in this embodiment, the voltage changes of the first battery E1 and the second battery E2 always cancel each other out, thereby achieving the overall stability of the terminal voltage of the power battery pack.

[0077] Figures 5 - 8 It can be used for the self-heating of the battery before the vehicle starts. The battery pack after oscillating heating has good discharge performance, which is convenient for the vehicle to start. After the vehicle starts, the other electrical components in the vehicle can generate heat that can be used to heat the battery pack to ensure the performance of the battery pack during driving. Figures 5 - 8 It can also be used for heating before or during the charging of the vehicle. The battery pack after oscillating heating has good charging performance, which is convenient for charging the battery pack. During the charging process, the battery pack generates heat by itself to ensure the smooth progress of the charging process.

[0078] Optionally, taking the first multi-phase inverter bridge and the second multi-phase inverter bridge as three-phase inverter bridges, and the first multi-phase motor and the second multi-phase motor as three-phase motors as an example, please refer to Figure 9 , the battery self-heating system further includes a first switch K1, a second switch K2, and a third switch K3, wherein the first switch K1, the second switch K2, and the third switch K3 are all two-position switches.

[0079] The negative terminal of the first battery pack E1 is connected to the stationary contact a of the first switch K1. The first moving contact b of the first switch K1 is connected to the neutral point n1 of the three-phase windings of the first multi-phase motor 30. The second moving contact c of the first switch K1 is respectively connected to the positive terminal of the first capacitor C1, the positive terminal of the first multi-phase inverter bridge 10, the positive terminal of the second capacitor C2, and the positive terminal of the second multi-phase inverter bridge 20;

[0080] The negative terminal of the first battery pack E1 and the positive terminal of the second battery pack E2 are both connected to the first moving contact b of the second switch K2. The second moving contact c of the second switch K2 is respectively connected to the negative terminal of the second battery pack E1, the negative terminal of the second capacitor C2, and the negative terminal of the second multi-phase inverter bridge 20. The stationary contact a of the second switch K2 is respectively connected to the negative terminal of the first capacitor C1 and the negative terminal of the first multi-phase inverter bridge 10;

[0081] The first moving contact b of the third switch K3 is connected to the second moving contact b of the first switch K1 and the neutral point n1 of the first polyphase motor 30 respectively. The second moving contact c of the third switch K3 is connected to the negative terminal of the first battery pack E1 and the positive terminal of the second battery pack E2 respectively. The static contact a of the third switch K3 is connected to the neutral point n2 of the three-phase windings of the second polyphase motor.

[0082] Optionally, in this embodiment, the first switch K1, the second switch K2, and the third switch K3 are used to establish the connections between various components of the circuit. Therefore, the first switch K1, the second switch K2, and the third switch K3 are not limited to the above-mentioned double-position switches, and can also be single-position switches, three-position switches, etc., as long as the above connections can be established. For example, the first switch K1 may include two single-position switches, which are respectively used to establish the connection between the positive terminal of the first battery pack E1 and the positive terminal of the first capacitor C1, and the connection between the positive terminal of the first battery pack E1 and the first polyphase motor 30. Similarly, the second switch K2 may also include two single-position switches, which can respectively establish the connection between the negative terminal of the first battery pack E1 and the negative terminal of the first capacitor C1, and the connection between the negative terminal of the second battery pack E2 and the negative terminal of the first capacitor C1.

[0083] In the scenario of oscillating heating, such as Figure 9 As shown, the controller controls the static contact a and the first moving contact b of the first switch K1 to be connected to establish the connection between the first battery pack E1 and the neutral point n1 of the first polyphase motor 30, controls the static contact a and the first moving contact b of the second switch K2 to be connected, and establishes the connection between the first battery pack E1, the first capacitor C1, and the first polyphase inverter bridge 10, and controls the static contact a and the second moving contact c of the third switch K3 to be connected to establish the connection between the second battery pack E2, the first battery pack E1, and the second polyphase motor 40.

[0084] In the first preset state, the controller controls the lower arm of the first multi-phase inverter bridge 10 to conduct. The current flows out from the positive terminal of the first battery pack E1, passes through the ab contacts of the first switch K1, flows through the first multi-phase motor 30, the lower arm of the first multi-phase inverter bridge 10, and the ab contacts of the second switch K2 in sequence, and returns to the negative terminal of the first battery pack E1, forming a discharge loop of the first battery pack E1. In this loop, the first battery pack E1 discharges to charge the multi-phase windings of the first multi-phase motor 30. At the same time, the controller controls the upper arm of the second multi-phase inverter bridge 20 to conduct. The current flows out from the positive terminal of the second capacitor C2, passes through the upper arm of the second multi-phase inverter bridge 20, the second multi-phase motor 40, and the ac contacts of the third switch K3 in sequence, and flows into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and then flows back from the negative terminal of the second battery pack E2 to the negative terminal of the second capacitor C2, forming a discharge loop of the second capacitor C2. In this loop, the second capacitor C2 discharges to charge the second battery pack E2 and the second multi-phase motor 40.

[0085] The controller is further configured to, in the second preset state, control the upper arm of the first multi-phase inverter bridge 10 to conduct, so as to control the first battery pack E1 and the first multi-phase motor 30 to discharge to charge the first capacitor C1, and control the lower arm of the second multi-phase inverter bridge 20 to conduct, so as to control the second multi-phase motor 40 to discharge to charge the second battery pack E2.

[0086] In the second preset state, the controller controls the upper arm of the first multi-phase inverter bridge 10 to conduct (the power switch device VT in the upper arm can be closed, or the power switch device VT in the upper arm can be disconnected, and the current flows through the diode VD). The current flows out from the positive terminal of the first battery pack E1, passes through the ab contacts of the first switch K1, the first multi-phase motor 30, the upper arm of the first multi-phase inverter bridge 10, and the first capacitor C1 in sequence, and then flows back to the negative terminal of the first battery pack E1 through the ab contacts of the second switch K2, forming a loop. In the first preset state, after the first multi-phase motor 30 is charged, it stores electrical energy. Therefore, in this loop, the first battery pack E1 and the first multi-phase motor 30 discharge to charge the first capacitor C1. At the same time, the controller controls the lower arm of the second multi-phase inverter bridge to conduct. In the first preset state, the second multi-phase motor 40 stores electrical energy after being charged. Due to the freewheeling characteristic of the second multi-phase motor 40, the second multi-phase motor 40 discharges. The current flows out from the midpoint n2 of the second multi-phase motor 40, passes through the ac contacts of the third switch K3, and flows into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and then flows out from the negative terminal of the second battery pack E2, flows into the lower arm of the second multi-phase inverter bridge 20, and then returns to the second multi-phase motor 40. In this loop, the second multi-phase motor 40 discharges to charge the second battery pack E2.

[0087] The controller is further configured to, in a third preset state, control the upper bridge arm of the first multiphase inverter bridge 10 to conduct, so as to control the first capacitor C1 to discharge and charge the first multiphase motor 30 and the first battery pack E1, and control the lower bridge arm of the second multiphase inverter bridge 20 to conduct, so as to control the second battery pack E2 to discharge and charge the second multiphase motor 40.

[0088] In the third preset state, the controller controls the upper bridge arm of the first multiphase inverter bridge 10 to conduct. The current flows out from the positive terminal of the first capacitor C1, sequentially passes through the upper bridge arm of the first multiphase inverter bridge 10, the first multiphase motor 30, and the ab contact of the first switch K1, and then flows into the positive terminal of the first battery pack E1 to charge the first battery pack E1. After that, the current flows out from the negative terminal of the first battery pack E1, passes through the ab contact of the second switch K2, and then flows back to the negative terminal of the first capacitor C1 to form a loop. Since the first capacitor C1 stores electrical energy during the second preset state, in this loop, the first capacitor C1 discharges to charge the first battery pack E1 and the first multiphase motor 30. At the same time, the controller controls the lower bridge arm of the second multiphase inverter bridge 20 to conduct. The current flows out from the positive pole of the second battery pack E2, sequentially passes through the ac contact of the third switch K3, the second multiphase motor 40, and the lower bridge arm of the second multiphase inverter bridge 20, and then flows back to the negative pole of the second battery pack E2 to form a loop. In this loop, the second battery pack E2 discharges to charge the second multiphase motor 40.

[0089] The controller is further configured to, in a fourth preset state, control the lower bridge arm of the first multiphase inverter bridge 10 to conduct, so as to control the first multiphase motor 30 to discharge and charge the first battery pack E1, and control the upper bridge arm of the second multiphase inverter bridge 20 to conduct, so as to control the second battery pack E2 and the second multiphase motor 40 to discharge and charge the second capacitor.

[0090] In the fourth preset state, the controller controls the lower arm of the first multiphase inverter bridge 10 to conduct. In the third preset state, the first multiphase motor 30 stores electrical energy through charging. Due to the freewheeling performance of the motor windings of the first multiphase motor 30, the current flows out from the first multiphase motor 30, flows into the positive terminal of the first battery pack E1 through the ab contacts of the first switch K1, charges the first battery pack E1, then flows out from the negative terminal of the first battery pack E1, successively flows through the ab contacts of the second switch K2 and the lower arm of the first multiphase inverter bridge 10, and returns to the first multiphase motor 30 to form a loop. In this loop, the first multiphase motor 30 discharges to charge the first battery pack E1. At the same time, the controller controls the lower arm of the second multiphase inverter bridge 20 to conduct. The current flows out through the second battery pack E2, successively flows through the second multiphase motor 40, the upper arm of the second multiphase inverter bridge 20, and the second capacitor C2 through the ac contacts of the third switch K3, and then returns to the negative terminal of the second battery pack E2. Since the second multiphase motor 40 has stored electrical energy through charging in the third preset state, in this loop, the second battery pack E2 and the second multiphase motor 40 discharge to charge the second capacitor C2.

[0091] Please refer to Figure 10 , the controller is further configured to control the static contact a of the first switch K1 to be connected to the second moving contact c of the first switch K1, the static contact a of the second switch K2 to be connected to the second moving contact c of the second switch K2, and the third switch K3 to be disconnected, so as to control the first battery pack E1 and the second battery pack E2 to supply power to the first multiphase motor 30 and the second multiphase motor 40 to drive the vehicle.

[0092] Optionally, please refer to Figure 11 , the battery self - heating system further includes: a fourth switch K4.

[0093] One end of the fourth switch K4 is respectively connected to the second moving contact c of the first switch K1, the positive terminal of the second capacitor C2, the positive terminal of the second multiphase inverter bridge 20, the positive terminal of the first capacitor C1, and the positive terminal of the first multiphase inverter bridge 10. The other end of the fourth switch K4 is used to be connected to the positive terminal of the DC charging pile 50. The controller is connected to the fourth switch K4. The negative terminal of the DC charging pile 50 is respectively connected to the negative terminal of the second capacitor C2 and the negative terminal of the second multiphase inverter bridge 20.

[0094] The controller is further configured to control the static contact a of the first switch K1 to be connected to the first moving contact b of the first switch K1, the static contact a of the second switch K2 to be connected to the second moving contact c of the second switch K2, the static contact a of the third switch K3 to be connected to the first moving contact b of the third switch K3, and the fourth switch K4 to be closed, so as to control the DC charging pile 50 to charge the first battery pack E1 and the second battery pack E2 through the first multiphase inverter bridge 10, the first multiphase motor 30, the second multiphase inverter bridge 20, and the second multiphase motor 40.

[0095] Optionally, the controller is further configured to, in a fifth preset state, control the upper bridge arm of the first multiphase inverter bridge 10 and the upper bridge arm of the second multiphase inverter bridge 20 to be turned on, so as to control the current of the DC charging pile 50 to charge the first battery pack E1 and the second battery pack E2 through the upper bridge arm of the first multiphase inverter bridge 10 and the first multiphase motor 30, and to charge the first battery pack E1 and the second battery pack E2 through the upper bridge arm of the second multiphase inverter bridge 20 and the second multiphase motor 40.

[0096] Please refer to Figure 12 , in the fifth preset state, the controller controls the upper bridge arm of the first multiphase inverter bridge 10 and the upper bridge arm of the second multiphase inverter bridge 20 to be turned on. The current flows out from the positive terminal of the DC charging pile 50, passes through the fourth switch K4. One path of the current successively flows through the upper bridge arm of the first multiphase inverter bridge 10, the first multiphase motor 30, and the ab contact of the first switch K1 and flows into the positive terminal of the first battery pack E1 to charge the first battery pack E1, then flows from the negative terminal of the first battery pack E1 into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and the current flows back to the negative terminal of the DC charging pile 50 from the negative terminal of the second battery pack E2. The other path of the current passing through the fourth switch K4 from the positive terminal of the DC charging pile 50 successively flows through the upper bridge arm of the second multiphase inverter bridge 20, the second multiphase motor 40, the ab contact of the third switch K3, and the ab contact of the first switch K1, and then flows into the positive terminal of the first battery pack E1 to charge the first battery pack E1, then flows from the negative terminal of the first battery pack E1 into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and the current flows back to the negative terminal of the DC charging pile 50 from the negative terminal of the second battery pack E2. In this embodiment, the DC charging pile 50 directly charges the first battery pack E1 and the second battery pack E2.

[0097] Optionally, when the voltage of the DC charging pile 50 is higher than the voltage of the battery pack, when using the DC charging pile 50 to charge the vehicle, the on-off of the electrical components in the battery self-heating system can be controlled to control the step-down charging of the DC charging pile. On Figure 12 the basis of combining with Figure 13, after the fifth preset state, the controller is further configured to control the lower bridge arms of the first multi-phase inverter bridge 10 and the second multi-phase inverter bridge 20 to conduct in the sixth preset state, and charge the first battery pack E1 and the second battery pack E2 through the discharge of the first multi-phase motor 30 and the second multi-phase motor 40.

[0098] Please refer to Figure 13 , in the sixth preset state, the controller controls the lower bridge arms of the first multi-phase inverter bridge 10 and the second multi-phase inverter bridge 20 to conduct. In the fifth preset state, the first multi-phase motor 30 and the second multi-phase motor 40 store electrical energy during charging. Due to the freewheeling characteristics of the multi-phase motor windings in the multi-phase motor, the first multi-phase motor 30 discharges, and the current flows out from the midpoint of the first multi-phase motor 30, flows into the positive terminal of the first battery pack E1 through the ab contacts of the first switch K1, charges the first battery pack E1, then flows from the negative terminal of the first battery pack E1 into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and the current flows out from the negative terminal of the second battery pack E2, passes through the ac contacts of the second switch K2, and flows back to the first multi-phase motor 30 through the lower bridge arm of the first multi-phase inverter bridge 10. And the second multi-phase motor 40 discharges, and the current flows out from the midpoint of the second multi-phase motor 40, flows into the positive terminal of the first battery pack E1 through the ab contacts of the third switch K3 and the ab contacts of the first switch K1 to charge the first battery pack E1, then flows from the negative terminal of the first battery pack E1 into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and the current flows out from the negative terminal of the second battery pack E2 and flows back to the second multi-phase motor 40 through the lower bridge arm of the second multi-phase inverter bridge 20. The first multi-phase motor 30 and the second multi-phase motor 40 are discharged to charge the first battery pack E1 and the second battery pack E2. In this embodiment, the first battery pack E1 and the second battery pack E2 are alternately charged through the fifth preset state and the sixth preset state, realizing step-down charging of the DC charging pile.

[0099] Optionally, the duration of the fifth preset state is the first duration T1, the duration of the sixth preset state is the second duration T2, the discharge voltage of the DC charging pile is the first voltage U1, and the discharge voltage of the first multi-phase motor and the second multi-phase motor is the second voltage U2. Among them, due to the law of conservation of voltage, the following relationship exists among the first duration T1, the second duration T2, the first voltage U1, and the second voltage U2: U1*T1 = U2*(T1 + T2). That is, U2 = U1*T1 / (T1 + T2). The ratio of U1 to U2 can be adjusted by controlling the time ratio of T1 to T2, so as to control the charging voltage.

[0100] It should be noted that the conduction of the above-mentioned bridge arm can be the full conduction of all the bridge arms of the multi-phase inverter bridge, or the conduction of some of the bridge arms. For example, taking the multi-phase inverter bridge as a three-phase inverter bridge, the partial conduction can be the conduction of any one of the three bridge arms, or the conduction of any two of the three bridge arms.

[0101] Optionally, in addition to the above Figure 12 and Figure 13 shown charging methods, the first battery pack E1 and the second battery pack E2 can also be charged by the method shown in Figure 14 . Please refer to Figure 14 . The controller is further configured to control the static contact a of the first switch K1 to be connected to the second moving contact c of the first switch K1, the static contact a of the second switch K2 to be connected to the second moving contact c of the second switch K2, the third switch K3 to be disconnected, and the fourth switch K4 to be closed, so as to control the DC charging pile 50 to charge the first battery pack E1 and the second battery pack E2. Please refer to Figure 14 . The current flows out from the positive terminal of the DC charging pile 50, flows into the positive terminal of the first battery pack E1 through the ac contact of the first switch K1 to charge the first battery pack E1, then flows from the negative terminal of the first battery pack E1 into the positive terminal of the second battery pack E2 to charge the second battery pack E2, and the current flows back to the negative terminal of the DC charging pile 50 from the negative terminal of the second battery pack E2. It is realized that the current of the DC charging pile 50 directly charges the battery pack without passing through the capacitor, the multi-phase inverter bridge and the multi-phase motor. At the same time, multiple motors are used for self-heating, with a large heating current, improving the self-heating efficiency.

[0102] Optionally, during the battery self-heating process, in addition to the above Figures 4 - 9 wherein two motors participate in the oscillating heating, it can also be 3 motors, 4 motors or more motors. On the basis of Figure 4 , the battery self-heating system further includes a third self-heating module, and the third self-heating module is respectively connected to the second battery pack and the second self-heating module. The third self-heating module and the second self-heating module discharge or charge simultaneously. As shown in Figure 15 , the third self-heating module includes a third capacitor C3, a third multi-phase inverter bridge 60 and a third multi-phase motor 70. The third capacitor is connected in parallel with the third multi-phase inverter bridge, and the third multi-phase inverter bridge is connected in series with the third multi-phase motor and then connected in parallel with the second battery pack. On the basis of Figure 4 , in combination with the third capacitor C3, the third multi-phase inverter bridge 60 and the third multi-phase motor 70, they jointly participate in the charge and discharge temperature-rising process of the first battery pack E1 and the second battery pack E2.

[0103] In Figure 15Based on this, the battery self-heating system further includes a fourth self-heating module, and the fourth self-heating module is respectively connected to the first battery pack and the first self-heating module. The fourth self-heating module and the first self-heating module charge or discharge simultaneously. As Figure 16 shown, the fourth self-heating module includes a fourth capacitor (not shown in the figure), a fourth multiphase inverter bridge 80, and a fourth multiphase motor 90. The fourth capacitor is connected in parallel with the fourth multiphase inverter bridge, and after the fourth multiphase inverter bridge is connected in series with the fourth multiphase motor, it is connected in parallel with the first battery pack. In Figure 15 based on this, in combination with the fourth capacitor C4, the fourth multiphase inverter bridge 80, and the fourth multiphase motor 90, they jointly participate in the charge and discharge temperature-rising process of the first battery pack E1 and the second battery pack E2.

[0104] Optionally, Figure 5 the battery automatic heating system in can also heat and drive at the same time. For example, a loop is formed by the first multiphase inverter bridge 10, the first multiphase motor 30, the first battery pack E1, and the second battery pack E2, and another loop is formed by the second multiphase inverter bridge 20, the second multiphase motor 40, the first battery pack E1, and the second battery pack E2. In the two loops, one loop is used to drive the vehicle, and the other loop is used for oscillating heating to ensure the performance of the battery pack during the formation process.

[0105] Optionally, the present disclosure also provides a vehicle including the above battery self-heating system, and the battery in the vehicle is heated and raised in temperature through the battery self-heating system to ensure the performance of the battery in a low-temperature environment.

[0106] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0107] Furthermore, any combination can be made between various different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A battery self-heating system, characterized in that, Applied to a vehicle, the system includes: A power battery pack, which includes a first battery pack and a second battery pack connected in series; A first self-heating module, which is connected to the first battery pack; A second self-heating module, which is connected to the second battery pack; A controller, which is connected to the first self-heating module and the second self-heating module. The controller controls the alternate charge and discharge between the first self-heating module and the first battery pack, and controls the alternate charge and discharge between the second self-heating module and the second battery pack. When one of the first battery pack and the second battery pack is in a discharge state, the other of the first battery pack and the second battery pack is in a charge state; The first self-heating module includes a first multi-phase motor, a first capacitor, and a first multi-phase inverter bridge. Among them, the first capacitor and the first multi-phase inverter bridge are connected in parallel. The first multi-phase inverter bridge is connected in series with the first multi-phase motor and then connected in parallel with the first battery pack. Each phase of the motor winding of the first multi-phase motor is connected to each phase of the first multi-phase inverter bridge one by one; The second self-heating module includes a second multi-phase motor, a second capacitor, and a second multi-phase inverter bridge. Among them, the second capacitor and the second multi-phase inverter bridge are connected in parallel. The second multi-phase inverter bridge is connected in series with the second multi-phase motor and then connected in parallel with the second battery pack. Each phase of the motor winding of the second multi-phase motor is connected to each phase of the second multi-phase inverter bridge one by one; The controller is configured to, in a first preset state, control the lower bridge arm of the first multi-phase inverter bridge to conduct, so as to control the first battery pack to discharge and charge the first multi-phase motor, and control the upper bridge arm of the second multi-phase inverter bridge to conduct, so as to control the second capacitor to discharge and charge the second battery pack and the second multi-phase motor; The controller is further configured to, in a second preset state, control the upper bridge arm of the first multi-phase inverter bridge to conduct, so as to control the first battery pack and the first multi-phase motor to discharge and charge the first capacitor, and control the lower bridge arm of the second multi-phase inverter bridge to conduct, so as to control the second multi-phase motor to discharge and charge the second battery pack; The controller is further configured to, in a third preset state, control the upper bridge arm of the first multi-phase inverter bridge to conduct, so as to control the first capacitor to discharge and charge the first multi-phase motor and the first battery pack, and control the lower bridge arm of the second multi-phase inverter bridge to conduct, so as to control the second battery pack to discharge and charge the second multi-phase motor; The controller is further configured to, in a fourth preset state, control the lower bridge arm of the first multi-phase inverter bridge to conduct, so as to control the first multi-phase motor to discharge and charge the first battery pack, and control the upper bridge arm of the second multi-phase inverter bridge to conduct, so as to control the second battery pack and the second multi-phase motor to discharge and charge the second capacitor.

2. The system according to claim 1, characterized in that, It further includes: A first switch, a second switch, and a third switch. Among them, the first switch, the second switch, and the third switch are all two-position switches; The negative terminal of the first battery pack is connected to the static contact of the first switch. The first moving contact of the first switch is connected to the midpoint of the three-phase windings of the first polyphase motor. The second moving contact of the first switch is respectively connected to the positive terminal of the first capacitor, the positive terminal of the first polyphase inverter bridge, the positive terminal of the second capacitor, and the positive terminal of the second polyphase inverter bridge; The negative terminal of the first battery pack and the positive terminal of the second battery pack are both connected to the first moving contact of the second switch. The second moving contact of the second switch is respectively connected to the negative terminal of the second battery pack and the negative terminal of the second polyphase inverter bridge. The static contact of the second switch is respectively connected to the negative terminal of the first capacitor and the negative terminal of the first polyphase inverter bridge; The first moving contact of the third switch is respectively connected to the second moving contact of the first switch and the midpoint of the first polyphase motor. The second moving contact of the third switch is respectively connected to the negative terminal of the first battery pack and the positive terminal of the second battery pack. The static contact of the third switch is connected to the midpoint of the three-phase windings of the second polyphase motor; The first switch, the second switch, and the third switch are all connected to the controller. The controller is used to control the connection between the static contact and the first moving contact of the first switch to control the establishment of the connection between the first battery pack and the first polyphase motor, control the connection between the static contact and the first moving contact of the second switch, and establish the connection between the first battery pack and the first capacitor and the first polyphase inverter bridge, and control the connection between the static contact and the second moving contact of the third switch to establish the connection between the second battery pack, the first battery pack, and the second polyphase motor to achieve self-heating of the first battery pack and the second battery pack.

3. The system according to claim 2, wherein, The controller is further used to control the connection between the static contact and the second moving contact of the first switch, the connection between the static contact and the second moving contact of the second switch, and the disconnection of the third switch to control the first battery pack and the second battery pack to supply power to the first polyphase motor and the second polyphase motor to drive the vehicle.

4. The system according to claim 2, characterized in that It further includes: A fourth switch; One end of the fourth switch is respectively connected to the second moving contact of the first switch, the positive terminal of the second capacitor, and the positive terminal of the first polyphase inverter bridge. The other end of the fourth switch is used to be connected to the positive terminal of the DC charging port. The controller is connected to the fourth switch. The negative terminal of the DC charging port is respectively connected to the negative terminal of the second capacitor and the negative terminal of the second polyphase inverter bridge; The controller is further configured to control the static contact of the first switch to be connected to the first moving contact of the first switch, the static contact of the second switch to be connected to the second moving contact of the second switch, the static contact of the third switch to be connected to the first moving contact of the third switch, and the fourth switch to be closed, so as to charge the first battery pack and the second battery pack through the first polyphase inverter bridge, the first polyphase motor, the second polyphase inverter bridge, and the second polyphase motor.

5. The system according to claim 4, wherein the controller is further configured to, in a fifth preset state, control the upper bridge arms of the first polyphase inverter bridge and the second polyphase inverter bridge to be turned on, so as to control the current of the DC charging pile to charge the first battery pack and the second battery pack through the upper bridge arms of the first polyphase inverter bridge and the first polyphase motor, and charge the first battery pack and the second battery pack through the upper bridge arms of the second polyphase inverter bridge and the second polyphase motor.

6. The system according to claim 5, wherein the controller is further configured to, in a sixth preset state, control the lower bridge arms of the first polyphase inverter bridge and the second polyphase inverter bridge to be turned on, and charge the first battery pack and the second battery pack through the discharging of the first polyphase motor and the second polyphase motor.

7. The system according to claim 6, wherein The duration of the fifth preset state is a first duration T1, the duration of the sixth preset state is a second duration T2, the discharging voltage of the DC charging pile is a first voltage U1, and the discharging voltage of the first polyphase motor and the second polyphase motor is a second voltage U2. Wherein, the following relationship exists among the first duration T1, the second duration T2, the first voltage U1, and the second voltage U2: U1*T1 = U2*(T1 + T2).

8. The system according to claim 4, wherein the controller is further configured to control the static contact of the first switch to be connected to the second moving contact of the first switch, the static contact of the second switch to be connected to the second moving contact of the second switch, the third switch to be turned off, and the fourth switch to be closed, so as to control the DC charging pile to charge the first battery pack and the second battery pack.

9. The system according to claim 1, characterized in that, The system further includes: a third self-heating module, and the third self-heating module is respectively connected to the second battery pack and the second self-heating module.

10. The system according to claim 9, wherein The third self-heating module includes a third capacitor, a third polyphase inverter bridge, and a third polyphase motor; The third capacitor is connected in parallel with the third polyphase inverter bridge, and the third polyphase inverter bridge and the third polyphase motor are connected in series and then connected in parallel with the second battery pack.

11. The system according to claim 1, wherein The system further includes: a fourth self-heating module, and the fourth self-heating module is respectively connected to the first battery pack and the first self-heating module.

12. The system according to claim 11, wherein, The fourth self-heating module includes a fourth capacitor, a fourth polyphase inverter bridge, and a fourth polyphase motor; The fourth capacitor is connected in parallel with the fourth polyphase inverter bridge, and the fourth polyphase inverter bridge and the fourth polyphase motor are connected in series and then connected in parallel with the first battery pack.

13. A vehicle, characterized in that, Comprising the battery self-heating system according to any one of claims 1-12.

Images