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, and includes a first battery pack, a second battery pack, a first multiphase inverter, a second multiphase inverter, a first capacitor, a second capacitor, a first multiphase motor and a second multiphase motor. By controlling the on-off state of the first multiphase inverter, the first battery pack is alternately charged and discharged between the first multiphase motor and the first capacitor, and by controlling the on-off state of the second multiphase inverter, the second battery pack is alternately charged and discharged between the second multiphase motor and the second capacitor. And when one of the first battery pack and the second battery pack discharges, the other of the first battery pack and the second battery pack charges, that is, one of the two battery packs of the battery self-heating system charges and the other discharges, so that the total voltage fluctuation of the battery self-heating system is small. During the self-heating process of charging and discharging of the first battery pack and the second battery pack, the small voltage fluctuation can reduce the damage to the battery pack.

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 be greatly reduced. 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. Currently, the battery is heated by charging and discharging the battery, but during the current charging and discharging process, the battery voltage fluctuates greatly, and this fluctuation may damage the battery cells. 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, in the first aspect of the present disclosure, a battery self-heating system is provided, which is applied to a vehicle. The system includes: a first battery pack, a second battery pack, a first multiphase inverter, a second multiphase inverter, a first multiphase motor, a second multiphase motor, a first capacitor, and a second capacitor; the first battery pack is connected in parallel with the first multiphase inverter, each phase of the first multiphase inverter is connected to each phase of the multiphase motor windings of the first multiphase motor one by one, one end of the first capacitor is connected to the neutral point of the first multiphase motor, and the other end is connected to the negative terminal of the first battery pack; the second battery pack is connected in parallel with the second multiphase inverter, each phase of the second multiphase inverter is connected to each phase of the multiphase motor windings of the second multiphase motor one by one, one end of the second capacitor is connected to the neutral point of the second multiphase motor, and the other end is connected to the negative terminal of the second battery pack; the negative terminal of the first battery pack is connected to the positive terminal of the second battery pack; the first multiphase inverter is used to control the alternating charge and discharge between the first battery pack, the first multiphase motor, and the first capacitor through the on-off state, and the second multiphase inverter is used to control the alternating charge and discharge between the second battery pack, the second multiphase motor, and the second capacitor through the on-off state.

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

[0006] Optionally, the magnitude of the current flowing through the first battery pack in the first preset state is the same as the magnitude of the current flowing through the second battery pack in the second preset state, and the magnitude of the current flowing through the second battery pack in the third preset state is the same as the magnitude of the current flowing through the first battery pack in the fourth preset state.

[0007] Optionally, the controller is further configured to control the first switch and the second switch to be disconnected, control the static contact of the third switch to be connected to the second moving contact of the third switch, and control the static contact of the fourth switch to be connected to the first moving contact of the fourth switch, so as to control the first battery pack and the second battery pack to supply power to the first three-phase motor and the second three-phase motor to drive the vehicle.

[0008] Optionally, the system further includes: a first switch, a second switch, a third switch, and a fourth switch, wherein both the third switch and the fourth switch are three-way changeover switches; the first switch is disposed on a connection line between the first polyphase motor and the first capacitor; the second switch is disposed on a connection line between the second polyphase motor and the second capacitor; a stationary contact of the third switch is connected to a connection end of the first capacitor and the first polyphase motor, a first moving contact of the third switch is respectively connected to a negative terminal of the first battery pack and a positive terminal of the second battery pack, and a second moving contact of the third switch is connected to a negative terminal of the second battery pack; a stationary contact of the fourth switch is connected to an upper bridge arm of the second polyphase inverter, a first moving contact of the fourth switch is connected to a positive terminal of the first battery pack, and a second moving contact of the fourth switch is respectively connected to a negative terminal of the first battery pack and a positive terminal of the second battery pack.

[0009] Optionally, the system further includes a controller; the controller is respectively connected to the first switch, the second switch, the third switch, the fourth switch, the first polyphase inverter, and the second polyphase inverter; the controller is further configured to control the first switch and the second switch to be closed, control a stationary contact of the third switch and a first moving contact of the third switch to be connected, and control a stationary contact of the fourth switch and a second moving contact of the fourth switch to be connected, so as to control self-heating of the first battery pack and the second battery pack.

[0010] Optionally, the system further includes: a fifth switch, a sixth switch, and a seventh switch; the fifth switch is disposed on a connection line between an upper bridge arm of the first polyphase inverter and a positive terminal of a DC charging pile; the sixth switch is disposed on a connection line between a lower bridge arm of the second polyphase inverter and a negative terminal of the DC charging pile; the seventh switch is disposed on a line between an end point of the second polyphase motor and the positive terminal of the DC charging pile.

[0011] Optionally, the fifth switch, the sixth switch, and the seventh switch are all connected to the controller; the controller is further configured to control the first switch, the second switch, the third switch, the fourth switch, and the seventh switch to be disconnected, and control the fifth switch and the sixth switch to be closed, so as to control the DC charging pile to charge the first battery pack and the second battery pack.

[0012] Optionally, the controller is further configured to control the first switch and the second switch to be closed, control a stationary contact of the third switch and a second moving contact of the third switch to be connected, and control the second switch, the fourth switch, the fifth switch, and the sixth switch to be disconnected, so as to control the DC charging pile to perform boost charging on the first battery pack and the second battery pack.

[0013] Optionally, the controller is further configured to control the lower arm of the first multiphase inverter to conduct in a fifth preset state, so as to control the DC charging pile to charge the first multiphase motor; the controller is further configured to control the upper arm of the first multiphase motor to conduct in a sixth preset state, so as to control the DC charging pile and the first multiphase motor to charge the first battery pack and the second battery pack.

[0014] Optionally, the fifth switch, the sixth switch, and the seventh switch are all connected to the controller; the controller is further configured to control the first switch, the second switch, the fifth switch, and the sixth switch to close, control the static contact of the third switch to be connected to the first moving contact of the third switch, control the static contact of the fourth switch to be connected to the second moving contact of the fourth switch, and control the seventh switch to open, so as to control the DC charging pile to charge the first battery pack and the second battery pack when the first battery pack and the second battery pack heat up during the charging and discharging process.

[0015] A second aspect of the present disclosure provides a vehicle including the above battery self-heating system.

[0016] A battery self-heating system and a vehicle provided by the present disclosure. The system includes a first battery pack, a second battery pack, a first multiphase inverter, a second multiphase inverter, a first capacitor, a second capacitor, a first multiphase motor, and a second multiphase motor. By controlling the on-off state of the first multiphase inverter, the first battery pack is alternately charged and discharged between the first multiphase motor and the first capacitor, and by controlling the on-off state of the second multiphase inverter, the second battery pack is alternately charged and discharged between the second multiphase motor and the second capacitor. It can be understood that when the first battery pack is charged, the second battery pack is discharged, and when the first battery pack is discharged, the second battery pack is charged, that is, one of the two battery packs in the battery self-heating system is charged and the other is discharged, so that the overall voltage fluctuation of the battery self-heating system is small. During the self-heating process of charging and discharging of the first battery pack and the second battery pack, the small voltage fluctuation can reduce the damage to the battery pack.

[0017] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. They are used together with the following specific implementation to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0019] Figure 1 is a schematic diagram of a battery self-heating circuit in the prior art.

[0020] Figure 2 It is a circuit diagram of a battery self - heating system provided by an embodiment of the present disclosure.

[0021] Figure 3 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0022] Figure 4 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0023] Figure 5 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0024] Figure 6 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0025] Figure 7 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0026] Figure 8 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0027] Figure 9 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0028] Figure 10 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0029] Figure 11 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0030] Figure  12 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0031] Figure 13 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0032] Figure 14 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0033] Figure 15 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0034] Figure 16 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0035] Figure 17 It is a circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0036] Figure 18 It is the circuit diagram of another battery self - heating system provided by an embodiment of the present disclosure.

[0037] Description of the reference numerals

[0038] E1 First battery pack; E2 Second battery pack;

[0039] 10 First multiphase inverter; 20 Second multiphase inverter;

[0040] 30 First multiphase motor; 40 Second multiphase motor;

[0041] C1 First capacitor; C2 Second capacitor;

[0042] K1 First switch; K2 Second switch;

[0043] K3 Third switch; K4 Fourth switch;

[0044] K5 Fifth switch; K6 Sixth switch;

[0045] K7 Seventh switch; 50 Third multiphase inverter;

[0046] 60 Third multiphase motor; C3 Third capacitor;

[0047] 70 Fourth multiphase inverter; 80 Fourth multiphase motor;

[0048] C4 Fourth capacitor. Detailed implementation manners

[0049] The following will describe in detail the specific implementation manners of the present disclosure with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only for explaining and interpreting the present disclosure, and are not used to limit the present disclosure.

[0050] 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, are gradually coming into the public eye. Strong power requires good charge - 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 - 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 raise the temperature of the battery body to ensure the charge - discharge performance of the battery.

[0051] At present, there are two ways to heat the battery: external heating and internal heating. Among them, external heating heats the battery by adding an additional heating device. This heating method increases the cost due to the additional heating device, and the heating efficiency is low because the external heat dissipation is fast and there is a certain distance between the external temperature and the internal battery. Currently, another heating method, the principle of internal heating mainly uses the battery's cyclic charge and discharge, relying on the internal resistance of the battery itself to generate heat. For example, as Figure 1 shown, the battery self-heating circuit includes battery 1, capacitor 2, capacitor 3, inverter 4, and motor 5. Among them, battery 1, capacitor 2, and inverter 4 are connected in parallel, and the discharge and charge of battery 1 are realized through capacitor 2, capacitor 3, inverter 4, and motor 5, so that battery 1 steps down and steps up, thereby realizing self-heating during the charge and discharge process.

[0052] In the above step-down and step-up 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.

[0053] To solve the above problems, the present application provides a battery self-heating system applied to a vehicle. Please refer to Figure 2 , the battery self-heating system includes: the first battery pack E1, the second battery pack E2, the first multiphase inverter 10, the second multiphase inverter 20, the first multiphase motor 30, the second multiphase motor 40, the first capacitor C1, and the second capacitor C2.

[0054] The first battery pack E1 is connected in parallel with the first multiphase inverter 10. Each phase of the first multiphase inverter 10 is connected to each phase of the multiphase motor windings of the first multiphase motor 30 one by one. One end of the first capacitor C1 is connected to the neutral point of the first multiphase motor 30, and the other end is connected to the negative extreme of the first battery pack E1;

[0055] The second battery pack E2 is connected in parallel with the second multiphase inverter 20. Each phase of the second multiphase inverter 20 is connected to each phase of the multiphase motor windings of the second multiphase motor 40 one by one. One end of the second capacitor C2 is connected to the neutral point of the second multiphase motor 40, and the other end is connected to the negative extreme of the second battery pack E2;

[0056] Optionally, the first polyphase inverter 10 and the second polyphase inverter 20 can be a three-phase inverter, a four-phase inverter, a five-phase inverter, a six-phase inverter, a twelve-phase inverter, etc. Correspondingly, the first polyphase motor 30 and the second polyphase motor 40 can be a three-phase motor, a four-phase motor, a five-phase motor, a six-phase motor, a twelve-phase motor, etc.

[0057] The negative terminal of the first battery pack E1 is connected to the positive terminal of the second battery pack E2.

[0058] Optionally, the first battery pack E1 and the second battery pack E2 can be located in the same battery pack on the vehicle. It can be understood that the battery pack on the vehicle is divided into the first battery pack E1 and the second battery pack E2.

[0059] The first polyphase inverter 10 is used to alternately charge and discharge between the first battery pack E1, the first polyphase motor 30, and the first capacitor C1 by controlling the on-off state. The second polyphase inverter 20 is used to alternately charge and discharge between the second battery pack E2, the second polyphase motor 40, and the second capacitor C2 by controlling the on-off state.

[0060] It can be understood that the charging and discharging process of the above two battery packs can be as follows: when the first battery pack E1 discharges to charge the first polyphase motor 30 and the first capacitor C1, the second capacitor C2 discharges to charge the second polyphase motor 40. When the first polyphase motor 30 discharges to charge the first capacitor C1, the second polyphase motor 40 and the second capacitor C2 discharge to charge the second battery pack E2, so that when the voltage change of the battery self-heating system is small (the small voltage change can be understood as the voltage change within a preset voltage range), the first battery pack E1 and the second battery pack E2 heat up during the charging and discharging process, realizing multi-motor oscillation heating.

[0061] The first polyphase inverter 10 and the second polyphase inverter 20 are also used to, when the first capacitor C1 discharges to charge the first polyphase motor 30 by controlling the on-off state, the second battery pack E2 discharges to charge the second polyphase motor 40 and the second capacitor C2. When the first polyphase motor 30 and the first capacitor C1 discharge to charge the first battery pack E1, the second polyphase motor 40 discharges to charge the second capacitor C2, so that when the voltage change of the battery self-heating system is within the preset range, the first battery pack E1 and the second battery pack E2 heat up during the charging and discharging process, realizing multi-motor oscillation heating.

[0062] Among them, the on-off state refers to the closed or open state of the switching tubes of the upper or lower bridge arms of the multi-phase inverter. At most one of the upper and lower bridge arms of the same multi-phase inverter is conducting. For example, if the switching tube of the upper bridge arm of the first multi-phase inverter 10 is closed, the switching tube of the lower bridge arm of the first multi-phase inverter 10 is open. By the on-off states of the first multi-phase inverter 10 and the second multi-phase inverter 20, the first battery pack E1 and the second battery pack E2 discharge alternately, so that the total voltage fluctuation is small, reducing the damage to the battery pack cells.

[0063] The voltage change within a preset range can be understood as the total voltage fluctuation of the battery self-heating system being small. Among them, the preset range can be a relatively small range, for example, it can be 0 to 0.5 V (voltage unit, volt).

[0064] The battery self-heating system provided in this embodiment includes a first battery pack, a second battery pack, a first multi-phase inverter, a second multi-phase inverter, a first capacitor, a second capacitor, a first multi-phase motor, and a second multi-phase motor. By controlling the on-off state of the first multi-phase inverter, the first battery pack is controlled to alternately charge and discharge with the first multi-phase motor and the first capacitor, and by controlling the on-off state of the second multi-phase inverter, the second battery pack is controlled to alternately charge and discharge with the second multi-phase motor and the second capacitor. It can be understood that when the first battery pack is charging, the second battery pack is discharging, and when the first battery pack is discharging, the second battery pack is charging, that is, the two battery packs of the battery self-heating system are one charging and one discharging, so that the overall voltage fluctuation of the battery self-heating system is small. During the self-heating process of charging and discharging of the first battery pack and the second battery pack, the small voltage fluctuation can reduce the damage to the battery pack.

[0065] Optionally, taking the first multi-phase inverter, the second multi-phase inverter, the first multi-phase motor, and the second multi-phase motor as three-phase as an example, this embodiment can control the on-off of the switch control circuit. Please refer to Figure 3 The battery self-heating system further includes: a first switch K1, a second switch K2, a third switch K3, and a fourth switch K4. Among them, the third switch K3 and the fourth switch K4 are both three-way changeover switches.

[0066] The first switch K1 is arranged on the connection line between the first multi-phase motor 30 and the first capacitor C1;

[0067] The second switch K2 is arranged on the connection line between the second multi-phase motor 40 and the second capacitor C2;

[0068] The static contact a of the third switch K3 is connected to the connection end of the first capacitor C1 and the first polyphase motor 30. The first moving contact b of the third switch K3 is respectively connected to the negative terminal of the first battery pack E1 and the positive terminal of the second battery pack E2. The second moving contact c of the third switch K3 is connected to the negative terminal of the second battery pack E2;

[0069] The static contact a of the fourth switch K4 is connected to the upper bridge arm of the second polyphase inverter 20. The first moving contact b of the fourth switch K4 is connected to the positive terminal of the first battery pack E1. The second moving contact c of the fourth switch K4 is respectively connected to the negative terminal of the first battery pack E1 and the positive terminal of the second battery pack E2.

[0070] Optionally, the battery self-heating system further includes a controller (not shown in the figure). The controller is respectively connected to the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the first polyphase inverter 10, and the second polyphase inverter 20.

[0071] On the basis of Figure 3 , please refer to Figure 4 . In the scenario of battery self-heating, the controller controls the first switch K1 and the second switch K2 to close. The connection between the first polyphase motor 30 and the first capacitor C1 is established through the first switch K1. The connection between the second polyphase motor 40 and the second capacitor C2 is established through the second switch K2. The controller controls the static contact a of the third switch K3 and the first moving contact b of the third switch K3 to be connected. The connection between the first battery pack E1 and the first capacitor C1 is established through the ab contact of the third switch K3. And the controller controls the static contact a of the fourth switch K4 and the second moving contact c of the fourth switch K4 to be connected. The connection between the second battery pack E2 and the second polyphase inverter 20 is established through the ac contact of the fourth switch K4. By controlling the on / off of the above switches, the self-heating of the first battery pack E1 and the second battery pack E2 is controlled.

[0072] Optionally, the controller is further configured to, in a first preset state, control the upper bridge arm of the first polyphase inverter 10 to conduct, so as to control the first battery pack E1 to discharge and charge the first polyphase motor 30 and the first capacitor C1, and control the lower bridge arm of the second polyphase inverter 20 to conduct, so as to control the second capacitor C2 to discharge and charge the second polyphase motor 40; in a second preset state, control the lower bridge arm of the first polyphase inverter 10 to conduct, so as to control the first polyphase motor 30 to discharge and charge the first capacitor C1, and control the upper bridge arm of the second polyphase inverter 20 to conduct, so as to control the second polyphase motor 40 and the second capacitor C2 to discharge and charge the second battery pack E2.

[0073] Please refer to Figure 5 In the first preset state, the controller controls the upper bridge arm of the first multi-phase inverter 10 to conduct, and the current flows out from the positive terminal of the first battery pack E1, and sequentially flows into the first multi-phase motor 30 and the first capacitor C1 through the upper bridge arm of the first multi-phase inverter 10 to charge the first multi-phase motor 30 and the first capacitor C1. Then the current flows out from the first capacitor C1, passes through the ab contacts of the third switch K3, and flows back to the negative terminal of the first battery pack E1 to form a loop. In this loop, the first battery pack E1 discharges to charge the first multi-phase motor 30 and the first capacitor C1. At the same time, the controller also controls the lower bridge arm of the second multi-phase inverter 20 to conduct. The second capacitor C2 stores electrical energy in advance. The current flows out from the second capacitor C2, flows into the second multi-phase motor 40, charges the second multi-phase motor 40 and then flows out, and then flows back to the second capacitor C2 through the lower bridge arm of the second multi-phase inverter 20 to form a loop. In this loop, the second capacitor C2 discharges to charge the second multi-phase motor 40.

[0074] Please refer to Figure 6 In the second preset state, the controller controls the lower bridge arm of the first multi-phase inverter 10 to conduct, and the current flows out from the midpoint of the first multi-phase motor 30, flows into the first capacitor C1 to charge the first capacitor C1, and then flows out from the first capacitor C1, passes through the lower bridge arm of the first multi-phase inverter 10 and flows back to the first multi-phase motor 30 to form a loop. In this loop, the first multi-phase motor 30 discharges to charge the first capacitor C1. At the same time, the controller controls the upper bridge arm of the second multi-phase inverter 20 to conduct. The second capacitor C2 and the second multi-phase motor 40 discharge together. The current flows from the second multi-phase motor 40 through the upper bridge arm of the second multi-phase inverter 20 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 and flows back to the second capacitor C2 to form a loop. In this loop, the second capacitor C2 and the second multi-phase motor 40 discharge together to charge the second battery pack E2.

[0075] In the cycle of the first preset state and the second preset state, the voltage of the first battery pack E1 continuously decreases due to discharge, and the voltage drop is ∆U1 = I1 * Rcell1, where I1 refers to the current flowing through the first battery pack E1 in the first preset state, and Rcell1 refers to the internal resistance of the first battery pack E1. The charging voltage of the second battery pack E2 continuously increases, and the voltage increase is ∆U2 = I2 * Rcell2, where I2 refers to the current flowing through the second battery pack E2 in the second preset state, and Rcell2 refers to the internal resistance of the second battery pack E2. If the voltage change |∆U1 - ∆U2| of the battery self-charging system is within the preset range, it is considered that the voltage in the system is stable. In the case of stable system voltage, the first battery pack and the second battery pack can reduce the loss of the battery pack cells during the charge and discharge heating process.

[0076] Optionally, when the vehicle battery pack is evenly divided into a first battery group and a second battery group, the internal resistances of the two battery packs are the same, that is, Rcell1 = Rcell2. If I1 = I2, the voltage change of the battery self-charging system is 0, and the voltage in the battery self-charging system is the most stable.

[0077] The controller is further configured to, in a third preset state, control the lower bridge arm of the first multi-phase inverter 10 to conduct, so as to control the first capacitor C1 to discharge to charge the first multi-phase motor 30, and control the upper bridge arm of the second multi-phase inverter 20 to conduct, so as to control the second battery group E2 to discharge to charge the second multi-phase motor 40 and the second capacitor C2; in a fourth preset state, control the upper bridge arm of the first multi-phase inverter 10 to conduct, so as to control the first multi-phase motor 30 and the first capacitor C1 to discharge to charge the first battery group E1, and control the lower bridge arm of the second multi-phase inverter 20 to conduct, so as to control the second multi-phase motor 40 to discharge to charge the second capacitor C2.

[0078] Please refer to Figure 7 , in the third preset state, the controller controls the lower bridge arm of the first multi-phase inverter 10 to conduct. The current flows out from the first capacitor C1, flows into the first multi-phase motor 30 to charge the first multi-phase motor 30, and then flows out from the first multi-phase motor 30, passes through the lower bridge arm of the first multi-phase inverter 10 and flows back to the first capacitor C1 to form a loop. In this loop, the first capacitor C1 discharges to charge the first multi-phase motor 30. At the same time, the controller controls the upper bridge arm of the second multi-phase inverter 20 to conduct. The current flows out from the positive terminal of the second battery group E2, passes through the upper bridge arm of the second multi-phase inverter 20 and flows into the second multi-phase motor 40 and the second capacitor C2 in sequence, charges the second multi-phase motor 40 and the second capacitor C2, and then flows back from the second capacitor C2 to the negative terminal of the second battery group E2 to form a loop. In this loop, the second battery group E2 discharges to charge the second multi-phase motor 40 and the second capacitor C2.

[0079] Please refer to Figure 8, in the fourth preset state, the controller controls the upper bridge arm of the first multiphase inverter 10 to conduct, and the first capacitor C1 and the first multiphase motor 30 discharge together. The current flows out from the first multiphase motor 30, flows into the positive terminal of the first battery pack E1 through the upper bridge arm of the first multiphase inverter 10 to charge the first battery pack E1. The current flows out from the negative terminal of the first battery pack E1 and flows back to the first capacitor C1 to form a loop. In this loop, the first capacitor C1 and the first multiphase motor 30 discharge together to charge the first battery pack E1. At the same time, the controller controls the lower bridge arm of the second multiphase inverter 20 to conduct. The current flows out from the midpoint of the second multiphase motor 40, flows into the second capacitor C2 to charge the second capacitor C2, and then flows out from the second capacitor C2, flows back to the second multiphase motor 40 through the lower bridge arm of the second multiphase inverter 20 to form a loop. In this loop, the second multiphase motor 40 discharges to charge the second capacitor C2.

[0080] Similarly, in the cycle of the third preset state and the fourth preset state, the charging voltage of the first battery pack E1 continuously rises, and the rising voltage is ∆U3 = I2 * Rcell1, where I2 refers to the current flowing through the first battery pack E1 in the fourth preset state. The discharging voltage of the second battery pack E2 continuously drops, and the dropping voltage is ∆U4 = I4 * Rcell2, where I4 refers to the current flowing through the second battery pack E2 in the third preset state. If the voltage change |∆U3 - ∆U4| of the battery self-charging system is within the preset range, it is considered that the voltage in the system is stable. In the case of stable system voltage, the first battery pack and the second battery pack can reduce the loss of the battery pack cells during the charge and discharge heating process.

[0081] Optionally, when the vehicle battery pack is evenly divided into the first battery pack and the second battery pack, the internal resistances of the two battery packs are the same, that is, Rcell1 = Rcell2. When I3 = I4, the voltage change of the battery self-charging system is 0, and the voltage in the battery self-charging system is the most stable.

[0082] Optionally, please refer to Figure 9 , the controller is further configured to control the first switch K1 and the second switch K2 to be disconnected, control the static contact a of the third switch K3 to be connected to the second moving contact c of the third switch K3, and control the static contact a of the fourth switch K4 to be connected to the first moving contact b of the fourth switch K4, 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.

[0083] It can be understood that the first battery pack E1, the second battery pack E2, the ac contact of the third switch K3, the first multiphase inverter 10, and the first multiphase motor 30 form a loop. The first battery pack E1 and the second battery pack E2 discharge together to supply power to the first multiphase motor 30. The first battery pack E1, the second battery pack E2, the ab contact of the fourth switch K4, the second multiphase inverter 20, and the second multiphase motor 40 form a loop. The first battery pack E1 and the second battery pack E2 discharge together to supply power to the second multiphase motor 40. The first multiphase motor 30 and the second multiphase motor 40 jointly drive the vehicle.

[0084] Optionally, please refer to Figure 10 , on the basis of Figure 3 , the battery self-heating system further includes a fifth switch K5, a sixth switch K6, and a seventh switch K7.

[0085] The fifth switch K5 is arranged on the connection line between the upper bridge arm of the first multiphase inverter 10 and the positive terminal of the DC charging pile 6; the sixth switch K6 is arranged on the connection line between the lower bridge arm of the second multiphase inverter 20 and the negative terminal of the DC charging pile 6; the seventh switch K7 is arranged on the line between the end point of the second multiphase motor 40 and the positive terminal of the DC charging pile 6.

[0086] Optionally, the controller controls Figure 10 the switches in the battery self-charging system in Figure 11 to enable the DC charging pile to charge the battery pack. In one implementation, the controller controls the switches to directly charge the battery pack with the DC charging pile. The fifth switch K5, the sixth switch K6, and the seventh switch K7 are all connected to the controller. Please refer to

[0087] It can be understood that in Figure 11 , the fifth switch K5 is closed to connect the DC charging pile 6 and the first battery pack E1, and the sixth switch K6 is closed to connect the DC charging pile 6 and the second battery pack E2. The current flows out from the positive terminal of the DC charging pile 6, passes through the fifth switch K5 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 then flows back from the negative terminal of the second battery pack E2 into the DC charging pile 6, realizing the charging of the first battery pack E1 and the second battery pack E2 by the DC charging pile 6.

[0088] In another embodiment, the controller controls the switch to boost the DC charging pile to charge the battery pack, thereby improving the charging efficiency. The controller is further configured to control the first switch K1 and the second switch K2 to close, control the static contact a of the third switch K3 to connect with the second moving contact c of the third switch K3, and control the second switch K2, the fourth switch K4, the fifth switch K5, and the sixth switch K6 to open, so as to control the DC charging pile 6 to boost-charge the first battery pack E1 and the second battery pack E2.

[0089] When the DC charging pile 6 performs boost charging, the DC charging pile 6 can first charge and store electrical energy in the inductive element or capacitive element in the battery self-heating system, and then the element that has stored electrical energy and the DC charging pile 6 jointly charge the battery pack to achieve boost charging. As a way, the controller is further configured to control the lower arm of the first multiphase inverter 10 to conduct in the fifth preset state, so as to control the DC charging pile 6 to charge the first multiphase motor 30.

[0090] Please refer to Figure 12 , the first switch K1 and the seventh switch K7 are closed to connect the DC charging pile 6 and the first multiphase motor 30. In the fifth preset state, the current flows out from the positive terminal of the DC charging pile 6, passes through the lower arm of the first multiphase motor 30 to charge the first multiphase motor 30, and then flows back to the negative terminal of the DC charging pile 6.

[0091] The controller is further configured to control the upper arm of the first multiphase motor 30 to conduct in the sixth preset state, so as to control the DC charging pile 6 and the first multiphase motor 30 to charge the first battery pack E1 and the second battery pack E2.

[0092] Please refer to Figure 13 , the first multiphase motor 30 stores electrical energy when charging in the fifth preset state. Through the series power supply of the first multiphase motor 30 and the DC charging pile 6, the current flows out from the upper arm of the first multiphase motor 30, 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 then flows back to the DC charging pile 6 from the negative terminal of the second battery pack E2 through the ac contact of the third switch K3. In the sixth preset state, the series voltage of the first multiphase motor 30 and the DC charging pile 6 increases, and they jointly charge the battery pack to improve the charging rate.

[0093] In a cold environment, the charging and discharging performance of the vehicle's battery pack will be affected. When charging the vehicle's battery pack, in order to ensure the charging performance of the battery pack, battery self-heating can be performed while charging to improve the charging efficiency. Optionally, the fifth switch K5, the sixth switch K6, and the seventh switch K7 are all connected to the controller.

[0094] Based on Figure 4 and combined with Figure 11 , please refer to Figure 14 , the controller is further configured to control the first switch K1, the second switch K2, the fifth switch K5, and the sixth switch K6 to be closed, control the stationary contact a of the third switch K3 to be connected to the first moving contact b of the third switch K3, control the stationary contact a of the fourth switch K4 to be connected to the second moving contact c of the fourth switch K4, and control the seventh switch K7 to be opened, so that when the first battery pack E1 and the second battery pack E2 are heated up during the charging and discharging process, the DC charging pile 6 charges the first battery pack E1 and the second battery pack E2.

[0095] As described in the above embodiment, the controller controls the first switch and the second switch to be closed, controls the stationary contact of the third switch to be connected to the first moving contact of the third switch, and controls the stationary contact of the fourth switch to be connected to the second moving contact of the fourth switch, and controls the conduction conditions of the first multiphase inverter and the second multiphase inverter to control the first battery pack E1 and the second battery pack E2 to oscillate and heat up during the charging and discharging process. At the same time, the fifth switch K5 is closed to connect the DC charging pile 6 and the first battery pack E1, and the sixth switch K6 is closed to connect the DC charging pile 6 and the second battery pack E2. The current flows out from the positive terminal of the DC charging pile 6, flows into the positive terminal of the first battery pack E1 through the fifth switch K5 to charge the first battery pack E1, then flows into the positive terminal of the second battery pack E2 from the negative terminal of the first battery pack E1 to charge the second battery pack E2, and then flows back into the DC charging pile 6 from the negative terminal of the second battery pack E2, realizing the charging of the first battery pack E1 and the second battery pack E2 by the DC charging pile 6.

[0096] Optionally, in addition to being evenly divided into the first battery pack E1 and the second battery pack E2, the vehicle's battery pack can also be unevenly divided. When the battery cells of the battery pack are uneven, that is, the internal resistance Rcell1 of the first battery pack E1 and the internal resistance Rcell2 of the second battery pack E2 are different, as long as the voltage drop of the first battery pack and the voltage rise of the second battery pack are the same, or the voltage rise of the first battery pack and the voltage drop of the second battery pack are the same, that is, I1*Rcell1 = I2*Rcell2.

[0097] That is, it is only necessary to control the ratio of the self-heating currents of the first battery pack E1 and the second battery pack E2 to be I1 / I2 = Rcell2 / Rcell1. Assuming that the internal resistances of all battery cells are the same, then I1 / I2 = Rcell2 / Rcell1 = N2 / N1. Wherein, N1 is the number of battery cells included in the first battery pack E1, N2 is the number of battery cells included in the second battery pack E2, Rcell1 is the total internal resistance of the first battery pack E1, and Rcell2 is the total internal resistance of the second battery pack E2.

[0098] 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 the above two groups, correspondingly, there are n multi-phase motors and multi-phase inverters matched with 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, assuming that the numbers 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.

[0099] Optionally, when there are m multi-phase motors and the multi-phase inverters matched with 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 inverters to be equal to the current of the battery pack, wherein the currents of each electronic control of the battery pack are not equal.

[0100] Optionally, during the self-heating process of the battery, in addition to the above Figures 2 - 14 two motors participating in the oscillating heating, it can also be 3 motors, 4 motors or more motors. For example, there can be 3 motors in the system. As Figure 15 shown, the battery self-heating system further includes a third multi-phase inverter and a third multi-phase motor. On the basis of Figure 2 , in combination with the third multi-phase inverter 50 and the third multi-phase motor 60, they jointly participate in the charging and discharging temperature-rising process of the first battery pack E1 and the second battery pack E2. On the basis of Figure 15 , as Figure 16 shown, the battery self-heating system further includes a third capacitor C3.

[0101] For another example, there can be 4 motors in the system. As Figure 17 shown, the battery self-heating system further includes a fourth multi-phase inverter 70 and a fourth multi-phase motor 80. It can also include a fourth capacitor C4 as Figure 18 shown.

[0102] Optionally, the present disclosure also provides a vehicle, which includes a battery self-heating system, and the battery is oscillatingly heated through the battery self-heating system.

[0103] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0104] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0105] Furthermore, any combination can be made among the 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 first battery pack, a second battery pack, a first multiphase inverter, a second multiphase inverter, a first multiphase motor, a second multiphase motor, a first capacitor, and a second capacitor; The first battery pack is connected in parallel with the first multiphase inverter. Each phase of the first multiphase inverter is connected to each phase of the multiphase motor windings of the first multiphase motor one by one. One end of the first capacitor is connected to the neutral point of the first multiphase motor, and the other end is connected to the negative terminal of the first battery pack; The second battery pack is connected in parallel with the second multiphase inverter. Each phase of the second multiphase inverter is connected to each phase of the multiphase motor windings of the second multiphase motor one by one. One end of the second capacitor is connected to the neutral point of the second multiphase motor, and the other end is connected to the negative terminal of the second battery pack; The negative terminal of the first battery pack is connected to the positive terminal of the second battery pack; The first multiphase inverter is used to control the alternating charge and discharge between the first battery pack, the first multiphase motor, and the first capacitor through the on-off state. The second multiphase inverter is used to control the alternating charge and discharge between the second battery pack, the second multiphase motor, and the second capacitor through the on-off state; When the first battery pack discharges to charge the first multiphase motor and the first capacitor, the second capacitor discharges to charge the second multiphase motor. When the first multiphase motor discharges to charge the first capacitor, the second multiphase motor and the second capacitor discharge to charge the second battery pack.

2. The system according to claim 1, wherein The system further includes a controller; The controller is configured to, in a first preset state, control the upper bridge arm of the first multiphase inverter to conduct, so as to control the first battery pack to discharge to charge the first multiphase motor and the first capacitor, and control the lower bridge arm of the second multiphase inverter to conduct, so as to control the second capacitor to discharge to charge the second multiphase motor; in a second preset state, control the lower bridge arm of the first multiphase inverter to conduct, so as to control the first multiphase motor to discharge to charge the first capacitor, and control the upper bridge arm of the second multiphase inverter to conduct, so as to control the second multiphase motor and the second capacitor to discharge to charge the second battery pack; The controller is further configured to, in a third preset state, control the lower bridge arm of the first multiphase inverter to conduct, so as to control the first capacitor to discharge to charge the first multiphase motor, and control the upper bridge arm of the second multiphase inverter to conduct, so as to control the second battery pack to discharge to charge the second multiphase motor and the second capacitor; in a fourth preset state, control the upper bridge arm of the first multiphase inverter to conduct, so as to control the first multiphase motor and the first capacitor to discharge to charge the first battery pack, and control the lower bridge arm of the second multiphase inverter to conduct, so as to control the second multiphase motor to discharge to charge the second capacitor.

3. The system according to claim 2, wherein The magnitude of the current flowing through the first battery pack in the first preset state is the same as the magnitude of the current flowing through the second battery pack in the second preset state, and the magnitude of the current flowing through the second battery pack in the third preset state is the same as the magnitude of the current flowing through the first battery pack in the fourth preset state.

4. The system according to claim 2, characterized in that, The system further includes: a first switch, a second switch, a third switch, and a fourth switch, wherein the third switch and the fourth switch are both three-way changeover switches; The first switch is arranged on the connection line between the first polyphase motor and the first capacitor; The second switch is arranged on the connection line between the second polyphase motor and the second capacitor; The stationary contact of the third switch is connected to the connection end of the first capacitor and the first polyphase motor. The first moving contact of the third switch is respectively connected to the negative electrode end of the first battery pack and the positive electrode end of the second battery pack, and the second moving contact of the third switch is connected to the negative electrode end of the second battery pack; The stationary contact of the fourth switch is connected to the upper bridge arm of the second polyphase inverter. The first moving contact of the fourth switch is connected to the positive electrode end of the first battery pack, and the second moving contact of the fourth switch is respectively connected to the negative electrode end of the first battery pack and the positive electrode end of the second battery pack.

5. The system according to claim 4, characterized in that, The system further includes a controller; The controller is respectively connected to the first switch, the second switch, the third switch, the fourth switch, the first polyphase inverter, and the second polyphase inverter; The controller is further configured to control the first switch and the second switch to be closed, control the stationary contact of the third switch to be connected to the first moving contact of the third switch, and control the stationary contact of the fourth switch to be connected to the second moving contact of the fourth switch, so as to control the self-heating of the first battery pack and the second battery pack.

6. The system according to claim 4, wherein The controller is further configured to control the first switch and the second switch to be disconnected, control the stationary contact of the third switch to be connected to the second moving contact of the third switch, and control the stationary contact of the fourth switch to be connected to the first moving contact of the fourth switch, 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.

7. The system according to claim 4, wherein The system further includes: a fifth switch, a sixth switch, and a seventh switch; The fifth switch is arranged on the connection line between the upper bridge arm of the first polyphase inverter and the positive electrode end of the DC charging pile; The sixth switch is arranged on the connection line between the lower bridge arm of the second polyphase inverter and the negative electrode end of the DC charging pile; The seventh switch is arranged on the line between the end point of the second polyphase motor and the positive electrode end of the DC charging pile.

8. The system according to claim 7, wherein The fifth switch, the sixth switch, and the seventh switch are all connected to the controller; The controller is further configured to control the first switch, the second switch, the third switch, the fourth switch, and the seventh switch to be turned off, and control the fifth switch and the sixth switch to be turned on, 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 7, wherein The controller is further configured to control the first switch and the second switch to be turned on, control the static contact of the third switch to be connected to the second moving contact of the third switch, and control the second switch, the fourth switch, the fifth switch, and the sixth switch to be turned off, so as to control the DC charging pile to charge the first battery pack and the second battery pack in a boost mode.

10. The system according to claim 9, wherein The controller is further configured to, in a fifth preset state, control the lower bridge arm of the first multiphase inverter to be turned on, so as to control the DC charging pile to charge the first multiphase motor; The controller is further configured to, in a sixth preset state, control the upper bridge arm of the first multiphase motor to be turned on, so as to control the DC charging pile and the first multiphase motor to charge the first battery pack and the second battery pack.

11. The system according to claim 9, wherein The fifth switch, the sixth switch, and the seventh switch are all connected to the controller; The controller is further configured to control the first switch, the second switch, the fifth switch, and the sixth switch to be turned on, control the static contact of the third switch to be connected to the first moving contact of the third switch, control the static contact of the fourth switch to be connected to the second moving contact of the fourth switch, and control the seventh switch to be turned off, so as to control the DC charging pile to charge the first battery pack and the second battery pack when the first battery pack and the second battery pack heat up during the charge and discharge process.

12. A vehicle, characterized in that, Comprising the battery self-heating system according to any one of the above claims 1-11.

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