Battery self-heating system and vehicle

Abstract

The present disclosure relates to a battery self-heating system and a vehicle, so as to avoid vehicle charging failure during the battery self-heating process. The system includes: a power battery pack, a first heating module, a second heating module, and a controller. The power battery pack includes a first battery pack and a second battery pack connected in series; the first heating module includes a first heating sub-module and a second heating sub-module, the second heating module includes a third heating sub-module and a fourth heating sub-module, the controller is connected to the first heating module and the second heating module, and the controller is configured to: control the alternating charge and discharge between the first heating module and the first battery pack, control the alternating charge and discharge between the second heating module and the second battery pack, and 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.

Description

Technical Field

[0001] The present disclosure relates to electric vehicle technologies, 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 raise the temperature of the battery body to ensure the charge and discharge performance of the battery. In related technologies, battery heating is achieved through the alternating charge and discharge between the battery pack and the energy storage element, but in the current charge and discharge process, the terminal voltage of the battery pack fluctuates greatly. 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, a first aspect of the present disclosure provides a battery self-heating system applied to a vehicle, and the system includes:

[0005] A power battery pack, where the power battery pack includes a first battery group and a second battery group connected in series;

[0006] A first heating module, where the first heating module includes a first heating sub-module and a second heating sub-module. The first connection end and the second connection end of the first heating sub-module are respectively connected to the positive and negative electrodes of the first battery group, the first connection end and the second connection end of the second heating sub-module are respectively connected to the positive and negative electrodes of the first battery group, and the third connection end of the first heating sub-module is connected to the third connection end of the second heating sub-module;

[0007] A second heating module, where the second heating module includes a third heating sub-module and a fourth heating sub-module. The first connection end and the second connection end of the third heating sub-module are respectively connected to the positive and negative electrodes of the second battery group, the first connection end and the second connection end of the fourth heating sub-module are respectively connected to the positive and negative electrodes of the second battery group, and the third connection end of the third heating sub-module is connected to the third connection end of the fourth heating sub-module;

[0008] A controller, connected to the first heating module and the second heating module, and the controller is configured to: control the alternating charge and discharge between the first heating module and the first battery group, control the alternating charge and discharge between the second heating module and the second battery group, and 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.

[0009] Optionally, the first heating sub-module includes a first heating winding and a first switch, the second heating sub-module includes a second heating winding and a second switch, the first switch includes a first upper switch and a first lower switch connected in series, and the second switch includes a second upper switch and a second lower switch connected in series. Wherein, the first upper switch is connected to the positive electrode of the first battery pack, the first lower switch is connected to the negative electrode of the first battery pack, the first end of the first heating winding is connected to the connection point of the first upper switch and the first lower switch, the second end of the first heating winding is connected to the first end of the second heating winding, the second end of the second heating winding is connected to the connection point of the second upper switch and the second lower switch, the second upper switch is connected to the positive electrode of the first battery pack, and the second lower switch is connected to the negative electrode of the first battery pack;

[0010] The third heating sub-module includes a third heating winding and a third switch, the fourth heating sub-module includes a fourth heating winding and a fourth switch, the third switch includes a third upper switch and a third lower switch connected in series, and the fourth switch includes a fourth upper switch and a fourth lower switch connected in series. Wherein, the third upper switch is connected to the positive electrode of the second battery pack, the third lower switch is connected to the negative electrode of the second battery pack, the first end of the third heating winding is connected to the connection point of the third upper switch and the third lower switch, the second end of the third heating winding is connected to the first end of the fourth heating winding, the second end of the fourth heating winding is connected to the connection point of the fourth upper switch and the fourth lower switch, the fourth upper switch is connected to the positive electrode of the second battery pack, and the fourth lower switch is connected to the negative electrode of the second battery pack.

[0011] Optionally, the first heating winding is a multi-phase winding in the first drive motor of the vehicle, the first switch is a first multi-phase inverter in the first drive motor controller corresponding to the first drive motor, the first upper switch represents the upper bridge arm of the first multi-phase inverter, and the first lower switch represents the lower bridge arm of the first multi-phase inverter;

[0012] The second heating winding is a multi-phase winding in the second drive motor of the vehicle, the second switch is a second multi-phase inverter in the second drive motor controller corresponding to the second drive motor, the second upper switch represents the upper bridge arm of the second multi-phase inverter, and the second lower switch represents the lower bridge arm of the second multi-phase inverter;

[0013] The third heating winding is a polyphase winding in the third drive motor of the vehicle, the third switch is a third polyphase inverter in the third drive motor controller corresponding to the third drive motor, the third upper switch represents the upper arm of the third polyphase inverter, and the third lower switch represents the lower arm of the third polyphase inverter;

[0014] The fourth heating winding is a polyphase winding in the fourth drive motor of the vehicle, the fourth switch is a fourth polyphase inverter in the fourth drive motor controller corresponding to the fourth drive motor, the fourth upper switch represents the upper arm of the fourth polyphase inverter, and the fourth lower switch represents the lower arm of the fourth polyphase inverter.

[0015] Optionally, the controller is configured to: in a first preset state, control the upper arm of the first polyphase inverter to conduct, and control the lower arm of the second polyphase inverter to conduct, so as to control the first battery pack to discharge and charge the first heating winding and the second heating winding, and control the lower arm of the third polyphase inverter to conduct, and control the upper arm of the fourth polyphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the second battery pack;

[0016] The controller is configured to: in a second preset state, control the lower arm of the first polyphase inverter to conduct, and control the upper arm of the second polyphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the first battery pack, and control the upper arm of the third polyphase inverter to conduct, and control the lower arm of the fourth polyphase inverter to conduct, so as to control the second battery pack to discharge and charge the first heating winding and the second heating winding.

[0017] Optionally, the controller is further configured to: in the same preset state, control the ratio between the current value flowing through the first battery pack and the current value flowing through the second battery pack to be equal to the ratio between the resistance value of the second battery pack and the resistance value of the first battery pack.

[0018] Optionally, the system further includes: a first changeover switch, a second changeover switch, a third changeover switch, and a fourth changeover switch, wherein the third changeover switch and the fourth changeover switch are both two-position switches;

[0019] The first changeover switch is arranged on the connection line of the first heating winding and the second heating winding;

[0020] The second changeover switch is arranged on the connection line of the third heating winding and the fourth heating winding;

[0021] The static contact of the third switching switch is connected to the connection end of the lower arm of the first multiphase inverter and the lower arm of the second multiphase inverter. The first moving contact of the third switching switch is respectively connected to the negative electrode of the first battery pack and the positive electrode of the second battery pack, and the second moving contact of the third switching switch is connected to the negative electrode of the second battery pack;

[0022] The static contact of the fourth switching switch is connected to the connection end of the upper arm of the third multiphase inverter and the upper arm of the fourth multiphase inverter. The first moving contact of the fourth switching switch is connected to the positive electrode of the first battery pack, and the second moving contact of the fourth switching switch is respectively connected to the negative electrode of the first battery pack and the positive electrode of the second battery pack;

[0023] The first switching switch, the second switching switch, the third switching switch and the fourth switching switch are all connected to the controller, and the controller is configured to: control the first switching switch and the second switching switch to close, control the static contact of the third switching switch and the first moving contact of the third switching switch to be connected, and control the static contact of the fourth switching switch and the second moving contact of the fourth switching switch to be connected to realize self-heating of the first battery pack and the second battery pack.

[0024] Optionally, the controller is further configured to: control the first switching switch and the second switching switch to open, control the static contact of the third switching switch and the second moving contact of the third switching switch to be connected, and control the static contact of the fourth switching switch and the first moving contact of the fourth switching switch to be connected to control the first battery pack and the second battery pack to supply power to the first drive motor, the second drive motor, the third drive motor and the fourth drive motor to drive the vehicle.

[0025] Optionally, the system further includes a first charging switch and a second charging switch;

[0026] The first charging switch is arranged on the connection line between the charging port of the vehicle and the positive electrode of the first battery pack;

[0027] The second charging switch is arranged on the connection line between the charging port of the vehicle and the negative electrode of the second battery pack;

[0028] The controller is further configured to: when the vehicle is connected to a charging pile, control the first charging switch and the second charging switch to close to charge the power battery pack while realizing self-heating of the first battery pack and the second battery pack.

[0029] Optionally, the controller is further configured to: when the vehicle is connected to a charging pile, control the first charging switch and the second charging switch to close, and control the third switching switch and the fourth switching switch to open, so as to charge the power battery pack separately.

[0030] A second aspect of the present disclosure further provides a vehicle, including the battery self-heating system according to any one of the above first aspects.

[0031] The battery self-heating system provided by the present disclosure is applied to a vehicle. The system includes a power battery pack, a driving module, a first heating module, a second heating module, and a controller. The first heating module alternately charges and discharges with the first battery pack, and the second heating module alternately charges and discharges with the second battery pack. 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 during the self-heating process cancel each other out, so that the terminal voltage fluctuation of the power battery pack is small, thereby avoiding vehicle charging failure.

[0032] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Description of the Drawings

[0033] 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:

[0034] Figure 1 is a schematic diagram of a battery self-heating circuit in the related art;

[0035] Figure 2 is a schematic diagram of a battery self-heating system provided by an embodiment of the present disclosure;

[0036] Figure 3 is a schematic diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0037] Figure 4 is a schematic diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0038] Figure 5 is a circuit diagram of a battery self-heating system provided by an embodiment of the present disclosure;

[0039] Figure 6 is a schematic diagram of the current direction when a battery self-heating system provided by an embodiment of the present disclosure is working;

[0040] Figure 7It is a schematic diagram of the current direction when another battery self-heating system provided by an embodiment of the present disclosure operates;

[0041] Figure 8 It is a circuit diagram of another battery self-heating system provided by an embodiment of the present disclosure;

[0042] Figure 9 It is a schematic diagram of the current direction when another battery self-heating system provided by an embodiment of the present disclosure operates;

[0043] Figure 10 It is a schematic diagram of the current direction when another battery self-heating system provided by an embodiment of the present disclosure operates.

[0044] Description of reference numerals

[0045] 11 - Battery; 12 - Capacitor; 13 - Inverter; 14 - Motor winding; E1 - First battery pack; E2 - Second battery pack; K1 - First changeover switch; K2 - Second changeover switch; K3 - Third changeover switch; K4 - Fourth changeover switch; K5 - First charging switch; K6 - Second charging switch; 1 - First drive motor; 2 - First drive motor controller; 3 - Second drive motor; 4 - Second drive motor controller; 5 - Third drive motor; 6 - Third drive motor controller, 7 - Fourth drive motor; 8 - Fourth drive motor controller. Detailed implementation manners

[0046] The following will describe the detailed implementation manners of the present disclosure with reference to the accompanying drawings. It should be understood that the detailed implementation manners described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0047] It should be understood that the steps recorded in the method implementation manners of the present disclosure can be executed in different orders and / or executed in parallel. In addition, the method implementation manners may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this regard. The term "including" and its variants used herein are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0048] It should be noted that concepts such as "first" and "second" mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependent relationships. It should be noted that the modifications of "one" and "multiple" mentioned in this disclosure are illustrative rather than restrictive. Those skilled in the art should understand that unless clearly specified otherwise in the context, it should be understood as "one or more".

[0049] 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 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 raise the temperature of the battery body to ensure the charge and discharge performance of the battery.

[0050] Currently, 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 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. The principle of the other internal heating method 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, the battery self-heating circuit includes a battery 11, a capacitor 12, an inverter 13, and a motor winding 14. Among them, the battery 11, the capacitor 12, and the inverter 13 are connected in parallel, and the battery 11 is oscillated and heated through the inverter 13 and the motor winding 14. And during the oscillating heating process, the battery 11 is in an alternating charge and discharge state, so the battery voltage fluctuates greatly, and this fluctuation may damage the battery and reduce the service life of the battery.

[0051] In addition, if a charging pile is connected for DC charging during battery self-heating, limited by the heat generation principle of battery self-heating, that is, when a large current flows through the battery, the internal resistance of the battery generates heat, and then heats the battery. In other words, in order to generate more heat, with the internal resistance of the battery and the heating time unchanged, a larger self-heating current is required. And the battery voltage fluctuation ΔU = I * Rcell. When the total internal resistance Rcell of the battery remains unchanged, the larger the battery current I, the larger the battery voltage fluctuation ΔU. This fluctuation may cause 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. And due to the limitation of the topology itself, the current flowing through the motor winding must have an in and an out at the same time, that is, the heating current can only be the current limiting value of one-phase winding, resulting in limited heating power.

[0052] In view of this, the present disclosure provides a battery self-heating system and a vehicle to solve the above problems.

[0053] The following is a detailed description of the technical solutions of the present disclosure with examples.

[0054] An embodiment of the present disclosure provides a battery self-heating system applied to a vehicle. Referring to Figure 2 , the battery self-heating system includes: a power battery pack 21, a first heating module 22, a second heating module 23, and a controller 24.

[0055] Among them, the power battery pack 21 includes a first battery group E1 and a second battery group E2 connected in series. The first heating module 22 includes a first heating sub-module 221 and a second heating sub-module 222. The first connection end and the second connection end of the first heating sub-module 221 are respectively connected to the positive and negative electrodes of the first battery group E1. The first connection end and the second connection end of the second heating sub-module 222 are respectively connected to the positive and negative electrodes of the first battery group E1, and the third connection end of the first heating sub-module 221 is connected to the third connection end of the second heating sub-module 222. The second heating module 23 includes a third heating sub-module 231 and a fourth heating sub-module 232. The first connection end and the second connection end of the third heating sub-module 231 are respectively connected to the positive and negative electrodes of the second battery group E2. The first connection end and the second connection end of the fourth heating sub-module 232 are respectively connected to the positive and negative electrodes of the second battery group E2, and the third connection end of the third heating sub-module 231 is connected to the third connection end of the fourth heating sub-module 232. The controller 24 is connected to the first heating module 22 and the second heating module 23, and the controller 24 is configured to: control the first heating module 22 and the first battery group E1 to alternately charge and discharge, control the second heating module 23 and the second battery group E2 to alternately charge and discharge, and when one of the first battery group E1 and the second battery group E2 is in a discharging state, the other of the first battery group E1 and the second battery group E2 is in a charging state.

[0056] When the above battery self-heating system is used for battery self-heating, the voltage fluctuations of the first battery group and the second battery group cancel each other out, resulting in a small voltage fluctuation at the terminal of the power battery pack, thereby avoiding vehicle charging failure.

[0057] To enable those skilled in the art to better understand the battery self-heating system provided by the present disclosure, the above steps will be described in detail with examples below.

[0058] In a possible manner, referring to Figure 3, the first heating sub-module 221 includes a first heating winding 31 and a first switch 32, the second heating sub-module 222 includes a second heating winding 33 and a second switch 34, the first switch 32 includes a first upper switch 321 and a first lower switch 322 connected in series, the second switch 34 includes a second upper switch 341 and a second lower switch 342 connected in series, wherein, the first upper switch 321 is connected to the positive electrode of the first battery pack E1, the first lower switch 322 is connected to the negative electrode of the first battery pack E1, the first end of the first heating winding 31 is connected to the connection point of the first upper switch 321 and the first lower switch 322, the second end of the first heating winding 31 is connected to the first end of the second heating winding 33, the second end of the second heating winding 33 is connected to the connection point of the second upper switch 341 and the second lower switch 342, the second upper switch 341 is connected to the positive electrode of the first battery pack E1, and the second lower switch 342 is connected to the negative electrode of the first battery pack E1.

[0059] Also, the third heating sub-module 231 includes a third heating winding 35 and a third switch 36, the fourth heating sub-module 232 includes a fourth heating winding 37 and a fourth switch 38, the third switch 36 includes a third upper switch 361 and a third lower switch 362 connected in series, the fourth switch 38 includes a fourth upper switch 381 and a fourth lower switch 382 connected in series, wherein, the third upper switch 361 is connected to the positive electrode of the second battery pack E2, the third lower switch 362 is connected to the negative electrode of the second battery pack E2, the first end of the third heating winding 35 is connected to the connection point of the third upper switch 361 and the third lower switch 362, the second end of the third heating winding 35 is connected to the first end of the fourth heating winding 37, the second end of the fourth heating winding 37 is connected to the connection point of the fourth upper switch 381 and the fourth lower switch 382, the fourth upper switch 381 is connected to the positive electrode of the second battery pack E2, and the fourth lower switch 382 is connected to the negative electrode of the second battery pack E2.

[0060] In a possible way, for a vehicle with multiple motors, the power battery pack can be self-heated by using multiple drive motor controllers and multiple drive motors on the vehicle. Refer to Figure 4 , taking a vehicle with multiple three-phase motors as an example, the power battery pack is divided into two battery packs, and four groups of drive motor controllers and drive motors are selected. One group of drive motor controllers and drive motors are respectively used as the first switch and the first heating winding of the first heating sub-module, one group of drive motor controllers and drive motors are respectively used as the second switch and the second heating winding of the second heating sub-module, one group of drive motor controllers and drive motors are respectively used as the third switch and the third heating winding of the third heating sub-module, and one group of drive motor controllers and drive motors are respectively used as the fourth switch and the fourth heating winding of the fourth heating sub-module.

[0061] Among them, refer to Figure 5, the first heating winding is a polyphase winding in the first drive motor 1 of the vehicle, the first switch is the first polyphase inverter in the first drive motor controller 2 corresponding to the first drive motor 1, the first upper switch represents the upper arm of the first polyphase inverter, and the first lower switch represents the lower arm of the first polyphase inverter. The second heating winding is a polyphase winding in the second drive motor 3 of the vehicle, the second switch is the second polyphase inverter in the second drive motor controller 4 corresponding to the second drive motor 3, the second upper switch represents the upper arm of the second polyphase inverter, and the second lower switch represents the lower arm of the second polyphase inverter. The third heating winding is a polyphase winding in the third drive motor 5 of the vehicle, the third switch is the third polyphase inverter in the third drive motor controller 6 corresponding to the third drive motor 5, the third upper switch represents the upper arm of the third polyphase inverter, and the third lower switch represents the lower arm of the third polyphase inverter. The fourth heating winding is a polyphase winding in the fourth drive motor 7 of the vehicle, the fourth switch is the fourth polyphase inverter in the fourth drive motor controller 8 corresponding to the fourth drive motor 7, the fourth upper switch represents the upper arm of the fourth polyphase inverter, and the fourth lower switch represents the lower arm of the fourth polyphase inverter.

[0062] In a possible manner, the controller is configured to: in a first preset state, control the upper arm of the first polyphase inverter to conduct, and control the lower arm of the second polyphase inverter to conduct, so as to control the first battery pack to discharge and charge the first heating winding and the second heating winding, and control the lower arm of the third polyphase inverter to conduct, and control the upper arm of the fourth polyphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the second battery pack.

[0063] Further, the controller is configured to: in a second preset state, control the lower arm of the first polyphase inverter to conduct, and control the upper arm of the second polyphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the first battery pack, and control the upper arm of the third polyphase inverter to conduct, and control the lower arm of the fourth polyphase inverter to conduct, so as to control the second battery pack to discharge and charge the first heating winding and the second heating winding.

[0064] Exemplarily, in the first preset state, referring to Figure 6, the upper arm of the first drive motor controller 2 is turned on and the lower arm is turned off. The upper arm of the second drive motor controller 4 is turned off and the lower arm is turned on. The first battery pack E1 charges the polyphase windings in the first drive motor 1 through the upper arm of the first drive motor controller 2. The charging current flows through the second drive motor 3 and charges the polyphase windings in the second drive motor 3. Finally, the charging current returns to the first battery pack E1 through the lower arm of the second drive motor controller 4. At this time, the first battery pack E1 discharges and the voltage drops. The upper arm of the third drive motor controller 6 is turned off, and the lower arm is turned on or off (according to the one-way conduction characteristic of the diode, when it is turned off, the current passes through the parasitic diode of the lower arm, the same below). The upper arm of the fourth drive motor controller 8 is turned on or off, and the lower arm is turned off. The polyphase windings in the third drive motor 5 and the fourth drive motor 7 transfer the stored energy through the upper arm of the fourth drive motor controller 8 to charge the second battery pack E2. At this time, the second battery pack E2 is charged and the voltage rises.

[0065] Exemplarily, in the second preset state, referring to Figure 7 , the upper arm of the first drive motor controller 2 is turned off, and the lower arm is turned on or off. The upper arm of the second drive motor controller 4 is turned on or off, and the lower arm is turned off. The polyphase windings in the first drive motor 1 and the second drive motor 3 transfer the stored energy through the upper arm of the second drive motor controller 4 to charge the first battery pack E1. At this time, the first battery pack E1 is charged and the voltage rises. The upper arm of the third drive motor controller 6 is turned on, and the lower arm is turned off. The upper arm of the fourth drive motor controller 8 is turned off, and the lower arm is turned on. The second battery pack E2 charges the polyphase windings in the third drive motor 5 through the upper arm of the third drive motor controller 6. The charging current flows through the fourth drive motor 7 and charges the polyphase windings in the fourth drive motor 7. Finally, the charging current returns to the second battery pack E2 through the lower arm of the fourth drive motor controller 8. At this time, the second battery pack E2 discharges and the voltage drops.

[0066] It should be noted that in the first preset state, the voltage of the first battery pack E1 continuously decreases, and the decrease amplitude ΔU1 = I1 * Rcell1. The voltage of the second battery pack E2 continuously increases, and the increase amplitude ΔU2 = I2 * Rcell2. In the second preset state, the voltage of the first battery pack E1 continuously increases, and the increase amplitude ΔU1 = I1 * Rcell1. The voltage of the second battery pack E2 continuously decreases, and the decrease amplitude ΔU2 = I2 * Rcell2. Therefore, by controlling the current I1 and resistance Rcell1 of the first battery pack and the current I2 and resistance Rcell2 of the second battery pack, the total voltage fluctuation of the power battery pack can be within a preset voltage fluctuation range, such as -0.5V to 0.5V. The specific preset voltage fluctuation range can be determined according to requirements, and the present disclosure does not limit this. Of course, on the premise that Rcell1 = Rcell2, as long as I1 = I2 is ensured, the total voltage fluctuation of the power battery pack can be 0. Furthermore, through the cycle of the first preset state and the second preset state, the cycle of charge and discharge of energy between the power battery pack and the motor winding is completed, thereby realizing battery self-heating.

[0067] In a possible manner, the controller is further configured to: in the same preset state, control the ratio between the current value flowing through the first battery pack and the current value flowing through the second battery pack to be equal to the ratio between the resistance value of the second battery pack and the resistance value of the first battery pack.

[0068] Exemplarily, from the charge and discharge process between the first battery pack and the second battery pack during the above battery self-heating process, it can be seen that the voltage fluctuation is related to the current and resistance of the battery. Since the resistance value of the battery pack is determined when dividing the battery pack, therefore, the total voltage fluctuation of the power battery pack can be within the preset voltage fluctuation range by adjusting the current of the battery pack. For example, if the power battery pack is divided into two battery packs with equal numbers of battery cells, then Rcell1 = Rcell2. If it is necessary to control the total voltage fluctuation of the power battery pack to be 0, then I1 = I2 can be controlled. Another example is that if the power battery pack is divided into two battery packs with unequal numbers of battery cells, and if it is necessary to control the total voltage fluctuation of the power battery pack to be 0, then I1 / I2 = Rcell2 / Rcell1 can be controlled. That is to say, when the ratio between the current value flowing through the first battery pack and the current value flowing through the second battery pack is equal to the ratio between the resistance value of the second battery pack and the resistance value of the first battery pack, the total voltage fluctuation of the power battery pack is equal to 0. Correspondingly, if it is only necessary to control the total voltage fluctuation of the power battery pack within the preset voltage fluctuation range, the current of the battery packs divided from the power battery pack can be controlled according to the control relationship that the larger the resistance of the battery pack, the smaller the current. Specifically, it can be determined according to requirements and tests, and the present disclosure does not limit this.

[0069] In addition, the power battery pack can also be divided into three battery groups, four battery groups, etc., and a heating module is allocated to each battery group. The present disclosure does not limit the number of battery groups and the number of battery cells in each battery group, as long as the total voltage fluctuation of the power battery pack is within the preset voltage fluctuation range. For example, taking the resistance values of each battery cell in the power battery pack as equal, assuming the number of battery cells included in each battery group are N1, N2, N3…Nn respectively, then the self-heating current of each battery group should satisfy I1 / I2 / I3 / …… / I n = Nn / …… / N3 / N2 / N1. Of course, multiple heating modules can also be connected in parallel to each battery group, as long as the sum of the currents of each heating module is controlled to be equal to the current of the battery group. The currents of the heating modules connected in parallel to the same battery group can be equal or unequal, and the present disclosure does not limit this. Moreover, compared with the related art where the heating current can only be the current limiting value of one-phase winding, in the battery self-heating system provided by the embodiments of the present disclosure, due to the addition of the drive motor and the drive motor controller, the maximum heating current can be the current limiting value of the N-phase winding. For example Figure 5 in the three-phase drive motor in, the maximum heating current is the current limiting value of the three-phase winding, that is, three times that of the related art, thereby improving the efficiency of battery self-heating.

[0070] In a possible way, a switch can be added to the circuit to control the on / off of the circuit. Referring to Figure 5 , the system further includes: a first change-over switch K1, a second change-over switch K2, a third change-over switch K3, and a fourth change-over switch K4, wherein the third change-over switch K3 and the fourth change-over switch K4 are both two-position switches.

[0071] Among them, the first conversion switch K1 is arranged on the connection line of the first heating winding (the polyphase winding in the first drive motor 1) and the second heating winding (the polyphase winding in the second drive motor 3). The second conversion switch K2 is arranged on the connection line of the third heating winding (the polyphase winding in the third drive motor 5) and the fourth heating winding (the polyphase winding in the fourth drive motor 7). The static contact a of the third conversion switch K3 is connected to the connection end of the lower bridge arm of the first polyphase inverter (in the first drive motor controller 2) and the lower bridge arm of the second polyphase inverter (in the second drive motor controller 4). The first moving contact b of the third conversion 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 conversion switch K3 is connected to the negative terminal of the second battery pack E2. The static contact a of the fourth conversion switch K4 is connected to the connection end of the upper bridge arm of the third polyphase inverter (in the third drive motor controller 6) and the upper bridge arm of the fourth polyphase inverter (in the fourth drive motor controller 8). The first moving contact b of the fourth conversion switch K4 is connected to the positive terminal of the first battery pack E1. The second moving contact c of the fourth conversion 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.

[0072] Furthermore, the first conversion switch K1, the second conversion switch K2, the third conversion switch K3 and the fourth conversion switch K4 are all connected to the controller, and the controller is configured to: control the first conversion switch K1 and the second conversion switch K2 to be closed, control the static contact a of the third conversion switch K3 and the first moving contact b of the third conversion switch K3 to be connected, and control the static contact a of the fourth conversion switch K4 and the second moving contact c of the fourth conversion switch K4 to be connected, so as to realize the self-heating of the first battery pack E1 and the second battery pack E2. Specifically, reference can be made to Figure 6 and 7 .

[0073] In a possible manner, the controller is further configured to: control the first conversion switch K1 and the second conversion switch K2 to be disconnected, control the static contact a of the third conversion switch K3 and the second moving contact c of the third conversion switch K3 to be connected, and control the static contact a of the fourth conversion switch K4 and the first moving contact b of the fourth conversion switch K4 to be connected, so as to control the first battery pack E1 and the second battery pack E2 to supply power to the first drive motor, the second drive motor, the third drive motor and the fourth drive motor to drive the vehicle.

[0074] Exemplarily, control the first conversion switch K1 and the second conversion switch K2 to be disconnected, control the static contact a of the third conversion switch K3 to be connected to the second moving contact c of the third conversion switch K3, and control the static contact a of the fourth conversion switch K4 to be connected to the first moving contact b of the fourth conversion switch K4. At this time, the first driving motor and the first driving motor controller, the second driving motor and the second driving motor controller, the third driving motor and the third driving motor controller, and the fourth driving motor and the fourth driving motor controller all form driving modules and are respectively connected in parallel with the power battery pack. The working process of the driving motor and the driving motor controller in the driving mode can refer to the related art, and the present disclosure will not elaborate herein.

[0075] In a possible manner, the system further includes a first charging switch K5 and a second charging switch K6. The first charging switch K5 is disposed on the connection line between the charging port of the vehicle and the positive electrode of the first battery pack E1, and the second charging switch K6 is disposed on the connection line between the charging port of the vehicle and the negative electrode of the second battery pack E2. The controller is further configured to: when the vehicle is connected to the charging pile, control the first charging switch K5 and the second charging switch K6 to be closed to charge the power battery pack while realizing self-heating of the first battery pack E1 and the second battery pack E2.

[0076] Exemplarily, when the vehicle needs to be directly connected for charging and perform battery self-heating, control the first charging switch K5, the second charging switch K6, the first conversion switch K1 and the second conversion switch K2 to be closed, control the static contact a of the third conversion switch K3 to be connected to the first moving contact b of the third conversion switch K3, and control the static contact a of the fourth conversion switch K3 to be connected to the second moving contact c of the fourth conversion switch K3. Refer to Figure 9 , which shows the arm states and current directions of the first heating module and the second heating module in the first preset state, as well as the current direction of direct connection charging. The arm states and current directions of the first heating module and the second heating module in the second preset state can refer to Figure 7 , and the present disclosure will not elaborate herein. Thus, while realizing self-heating of the first battery pack E1 and the second battery pack E2, the power battery pack is charged. Since the voltage fluctuations of the first battery pack and the second battery pack cancel each other out, the terminal voltage fluctuation of the power battery pack is small, thereby avoiding vehicle charging failure.

[0077] In a possible manner, the controller is further configured to: when the vehicle is connected to the charging pile, control the first charging switch and the second charging switch to be closed, and control the third conversion switch and the fourth conversion switch to be disconnected to charge the power battery pack separately.

[0078] Exemplarily, refer to Figure 10, when the vehicle needs direct charging, control the first charging switch K5 and the second charging switch K6. The first transfer switch K1 and the second transfer switch K2 can be disconnected or closed. Control the static contact a of the third transfer switch K3 not to connect to both the first moving contact b and the second moving contact c of the third transfer switch K3, and control the first moving contact b and the second moving contact c of the static contact a of the fourth transfer switch K4 and the second moving contact c of the fourth transfer switch K4 not to connect.

[0079] It should be noted that by using some of the drive motor controllers and drive motors in the multi-motor vehicle as a heating module to self-heat the power battery pack, that is, the drive motor controllers and drive motors can be used to drive the vehicle and also to self-heat the power battery pack, without the need to additionally add other components or heating devices. While meeting the need to heat the power battery pack, the cost is saved. However, for other single-motor vehicles or dual-motor vehicles, the self-heating function of the power battery pack can be achieved by adding switches and windings as a heating module. Of course, for multi-motor vehicles, the self-heating function can also be achieved by adding switches and windings as a heating module, and the present disclosure does not limit this.

[0080] Exemplarily, the switch can be composed of one-phase bridge arms or multi-phase bridge arms, or can also be other switch elements with the functions of conducting and disconnecting circuits. The winding can be a single-phase winding or a multi-phase winding, or can also be the winding in a single-phase motor or a multi-phase motor. The present disclosure does not limit this. And for the same battery pack, multiple heating modules can be connected. In the same preset state of each heating module, the bridge arm state and the current direction are consistent. In addition, for the heating module that does not participate in driving the vehicle, a six-phase bridge arm and a six-phase motor can be used to replace the two three-phase bridge arms and two three-phase motors as shown in Figure 5 Figure.

[0081] It should be noted that the controller can be the control unit in the drive motor controller or can also be an electronic device installed in the vehicle. The present disclosure does not limit this. A temperature sensor can also be set near the power battery pack to transmit the collected battery temperature to the controller in real time. When the battery temperature is lower than the preset threshold, the controller automatically controls the power battery pack to self-heat. A heating button can also be set on the vehicle. For example, it is reminded on the in-vehicle display screen that the power battery pack is in a low-temperature state. The driver can send a signal to start self-heating to the controller through the heating button set on the in-vehicle display screen. After receiving this signal, the controller controls the power battery pack to self-heat, etc. The present disclosure does not limit this.

[0082] In addition, during the process of controlling the battery pack to alternately charge and discharge, one or more of multiple bridge arms or switches can be controlled to conduct, so as to control the number of windings participating in self-heating. For example Figure 6Among them, one of the three upper bridge arms of the first drive motor controller 2 can be selected to conduct, so that the first battery pack E1 discharges to one of the windings connected to the first drive motor 1. Generally speaking, the more windings participating in self-heating, the higher the self-heating efficiency. In other possible implementation manners, the number of windings participating in self-heating can be controlled according to the battery temperature. For example, the lower the battery temperature, the more windings, and so on. The present disclosure does not limit this.

[0083] Based on the same inventive concept, an embodiment of the present disclosure further provides a vehicle, including the above battery self-heating system, which realizes heating and temperature rise of the battery in the vehicle through the battery self-heating system to ensure the performance of the battery in a low-temperature environment. And when the vehicle is charged by direct current, the power battery pack can also be self-heated.

[0084] The preferred embodiments of the present disclosure have been described in detail above with reference to 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.

[0085] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0086] In addition, 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 heating module, which includes a first heating sub-module and a second heating sub-module. The first connection end and the second connection end of the first heating sub-module are respectively connected to the positive and negative electrodes of the first battery pack. The first connection end and the second connection end of the second heating sub-module are respectively connected to the positive and negative electrodes of the first battery pack, and the third connection end of the first heating sub-module is connected to the third connection end of the second heating sub-module; A second heating module, which includes a third heating sub-module and a fourth heating sub-module. The first connection end and the second connection end of the third heating sub-module are respectively connected to the positive and negative electrodes of the second battery pack. The first connection end and the second connection end of the fourth heating sub-module are respectively connected to the positive and negative electrodes of the second battery pack, and the third connection end of the third heating sub-module is connected to the third connection end of the fourth heating sub-module; A controller, connected to the first heating module and the second heating module. The controller is configured to: control the first heating module and the first battery pack to alternately charge and discharge, control the second heating module and the second battery pack to alternately charge and discharge, and when controlling one of the first battery pack and the second battery pack to be in a discharge state, while the other of the first battery pack and the second battery pack is in a charging state, control the ratio between the current value flowing through the first battery pack and the current value flowing through the second battery pack to be equal to the ratio between the resistance value of the second battery pack and the resistance value of the first battery pack; Wherein, the first heating sub-module includes a first heating winding and a first switch. The first heating winding is a multi-phase winding in the first drive motor of the vehicle, and the first switch is a first multi-phase inverter in the first drive motor controller corresponding to the first drive motor; The second heating sub-module includes a second heating winding and a second switch. The second heating winding is a multi-phase winding in the second drive motor of the vehicle, and the second switch is a second multi-phase inverter in the second drive motor controller corresponding to the second drive motor; The third heating sub-module includes a third heating winding and a third switch. The third heating winding is a multi-phase winding in the third drive motor of the vehicle, and the third switch is a third multi-phase inverter in the third drive motor controller corresponding to the third drive motor; The fourth heating sub-module includes a fourth heating winding and a fourth switch. The fourth heating winding is a multi-phase winding in the fourth drive motor of the vehicle, and the fourth switch is a fourth multi-phase inverter in the fourth drive motor controller corresponding to the fourth drive motor.

2. The system according to claim 1, characterized in that The first switch includes a first upper switch representing the upper arm of the first multiphase inverter and a first lower switch representing the lower arm of the first multiphase inverter connected in series. The second switch includes a second upper switch representing the upper arm of the second multiphase inverter and a second lower switch representing the lower arm of the second multiphase inverter connected in series. Wherein, the first upper switch is connected to the positive electrode of the first battery pack, the first lower switch is connected to the negative electrode of the first battery pack, the first end of the first heating winding is connected to the connection point of the first upper switch and the first lower switch, the second end of the first heating winding is connected to the first end of the second heating winding, the second end of the second heating winding is connected to the connection point of the second upper switch and the second lower switch, the second upper switch is connected to the positive electrode of the first battery pack, and the second lower switch is connected to the negative electrode of the first battery pack; The third switch includes a third upper switch representing the upper arm of the third multiphase inverter and a third lower switch representing the lower arm of the third multiphase inverter connected in series. The fourth switch includes a fourth upper switch representing the upper arm of the fourth multiphase inverter and a fourth lower switch representing the lower arm of the fourth multiphase inverter connected in series. Wherein, the third upper switch is connected to the positive electrode of the second battery pack, the third lower switch is connected to the negative electrode of the second battery pack, the first end of the third heating winding is connected to the connection point of the third upper switch and the third lower switch, the second end of the third heating winding is connected to the first end of the fourth heating winding, the second end of the fourth heating winding is connected to the connection point of the fourth upper switch and the fourth lower switch, the fourth upper switch is connected to the positive electrode of the second battery pack, and the fourth lower switch is connected to the negative electrode of the second battery pack.

3. The system according to claim 2, wherein The controller is configured to: in a first preset state, control the upper arm of the first multiphase inverter to conduct, and control the lower arm of the second multiphase inverter to conduct, so as to control the first battery pack to discharge and charge the first heating winding and the second heating winding, and control the lower arm of the third multiphase inverter to conduct, and control the upper arm of the fourth multiphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the second battery pack; The controller is configured to: in a second preset state, control the lower arm of the first multiphase inverter to conduct, and control the upper arm of the second multiphase inverter to conduct, so as to control the first heating winding and the second heating winding to charge the first battery pack, and control the upper arm of the third multiphase inverter to conduct, and control the lower arm of the fourth multiphase inverter to conduct, so as to control the second battery pack to discharge and charge the first heating winding and the second heating winding.

4. The system according to claim 2, wherein The system further includes: a first change-over switch, a second change-over switch, a third change-over switch and a fourth change-over switch, wherein both the third change-over switch and the fourth change-over switch are two-position switches; The first changeover switch is arranged on the connection line between the first heating winding and the second heating winding; The second changeover switch is arranged on the connection line between the third heating winding and the fourth heating winding; The static contact of the third changeover switch is connected to the connection end of the lower bridge arm of the first polyphase inverter and the lower bridge arm of the second polyphase inverter. The first moving contact of the third changeover switch is respectively connected to the negative electrode end of the first battery pack and the positive electrode end of the second battery pack. The second moving contact of the third changeover switch is connected to the negative electrode end of the second battery pack; The static contact of the fourth changeover switch is connected to the connection end of the upper bridge arm of the third polyphase inverter and the upper bridge arm of the fourth polyphase inverter. The first moving contact of the fourth changeover switch is connected to the positive electrode end of the first battery pack. The second moving contact of the fourth changeover switch is respectively connected to the negative electrode end of the first battery pack and the positive electrode end of the second battery pack; The first changeover switch, the second changeover switch, the third changeover switch and the fourth changeover switch are all connected to the controller, and the controller is configured to: control the first changeover switch and the second changeover switch to close, control the static contact and the first moving contact of the third changeover switch to be connected, and control the static contact and the second moving contact of the fourth changeover switch to be connected, so as to realize self-heating of the first battery pack and the second battery pack.

5. The system according to claim 4, wherein The controller is further configured to: control the first changeover switch and the second changeover switch to disconnect, control the static contact and the second moving contact of the third changeover switch to be connected, and control the static contact and the first moving contact of the fourth changeover switch to be connected, so as to control the first battery pack and the second battery pack to supply power to the first drive motor, the second drive motor, the third drive motor and the fourth drive motor to drive the vehicle.

6. The system according to claim 4, characterized in that, The system further includes a first charging switch and a second charging switch; The first charging switch is arranged on the connection line between the charging port of the vehicle and the positive electrode of the first battery pack; The second charging switch is arranged on the connection line between the charging port of the vehicle and the negative electrode of the second battery pack; The controller is further configured to: when the vehicle is connected to a charging pile, control the first charging switch and the second charging switch to close, so as to charge the power battery pack while realizing self-heating of the first battery pack and the second battery pack.

7. The system according to claim 6, wherein The controller is further configured to: when the vehicle is connected to a charging pile, control the first charging switch and the second charging switch to close, and control the third changeover switch and the fourth changeover switch to disconnect, so as to charge the power battery pack separately.

8. A vehicle, characterized in that, Comprising the battery self-heating system according to any one of claims 1-7 above.

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